Agilent Technologies G3180B User guide

Agilent Technologies G3180B User guide
Agilent 7890A
Gas Chromatograph
Advanced User Guide
Agilent Technologies
Notices
© Agilent Technologies, Inc. 2009
No part of this manual may be reproduced
in any form or by any means (including
electronic storage and retrieval or translation into a foreign language) without prior
agreement and written consent from Agilent Technologies, Inc. as governed by
United States and international copyright
laws.
Manual Part Number
G3430-90015
Safety Notices
CAUTION
A CAUTION notice denotes a hazard. It
calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in damage to the product
or loss of important data. Do not
proceed beyond a CAUTION notice
until the indicated conditions are fully
understood and met.
Edition
Fifth edition, September 2009
Fourth edition, April 2009
Third edition, September 2008
Second edition, January 2008
First edition, April 2007
Printed in USA
Agilent Technologies, Inc.
2850 Centerville Road
Wilmington, DE 19808-1610 USA
安捷伦科技 (上海)有限公司
上海市浦东新区外高桥保税区
英伦路 412 号
联系电话:(800)820 3278
WA R N I N G
A WARNING notice denotes a hazard.
It calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in personal injury or
death. Do not proceed beyond a
WARNING notice until the indicated
conditions are fully understood and
met.
Firmware Version
This manual is written for 7890A GCs using
firmware version A.01.10.1.
Contents
1
Programming
Run Time Programming 14
Using run time events 14
Programming run time events
The run table 15
Adding events to the run table
Editing events in the run table
Deleting run time events 16
15
15
15
Clock Time Programming 17
Using clock time events 17
Programming clock time events
Adding events to the clock table
Editing clock time events 18
Deleting clock time events 18
17
17
User-Key Programming 19
To program a User Key 19
To play back (execute) the stored keystrokes
To erase the stored keystrokes 19
2
19
Configuration
About Configuration 23
Assigning GC resources to a device 23
Setting configuration properties 24
General Topics 25
Unlock the GC Configuration
Ignore Ready = 25
Information displays 25
Unconfigured: 26
25
Oven 27
To configure the oven 27
To configure the oven for cryogenic cooling
Front Inlet/Back Inlet 29
To configure the Gas type 29
To configure the PTV or COC coolant
To configure the MMI coolant 31
28
29
Column # 33
To configure a single column 33
To configure multiple columns 35
Advanced User Guide
3
Cryo Trap 40
Configure the cryo trap to the GC 40
Configure a heater to the cryo trap 40
Configure the coolant 40
Configure the user-configurable heater 41
Reboot the GC 41
Front Detector/Back Detector/Aux Detector/Aux Detector 2
To configure the makeup/reference gas 42
Lit offset 42
To configure the FPD heaters 42
Analog out 1/Analog out 2
Fast peaks
43
42
43
Valve Box 44
To assign a GC power source to a valve box heater
44
Thermal Aux 45
To assign a GC power source to an Aux thermal zone
To configure an MSD transfer line heater 45
To configure a nickel catalyst heater 46
To configure an AED transfer line heater 46
PCM A/PCM B/PCM C 47
To assign a GC communication source to a PCM
To configure a PCM 47
45
47
Pressure aux 1,2,3/Pressure aux 4,5,6/Pressure aux 7,8,9 49
To assign a GC communication source to an Aux EPC 49
To configure an auxiliary pressure channel 49
Status 50
The Ready/Not Ready status table 50
The setpoint status table 50
To configure the setpoint status table 50
Time 51
To set time and date 51
To use the stopwatch 51
Valve # 52
To configure a valve
52
Front injector/Back injector 53
Solvent Wash Mode (7683 ALS) 53
To configure an injector (7683 ALS) 54
Sample tray (7683 ALS)
Instrument
4
55
56
Advanced User Guide
3
Options
About Options
58
Calibration 59
Maintaining EPC calibration—inlets, detectors, PCM, and AUX
To zero all pressure sensors in all modules 61
Column calibration 61
Communication 65
Configuring the IP address for the GC
Keyboard and Display
4
65
66
Chromatographic Checkout
About Chromatographic Checkout
68
To Prepare for Chromatographic Checkout
To Check FID Performance
69
71
To Check TCD Performance
76
To Check NPD Performance
81
To Check uECD Performance
5
59
86
To Check FPD Performance (Sample 5188-5953)
91
To Verify FPD Performance (Sample 5188-5245)
98
Methods and Sequences
Creating Methods 106
To program a method 107
To program the ALS 107
To program the ALS sampler tray 107
To program the 7683B ALS bar code reader
To save a method 109
To load a stored method 109
Method mismatch 109
108
Creating Sequences 111
About the priority sequence 111
To program a sequence 111
To program a priority sequence 112
To program an ALS subsequence 113
To program a valve subsequence 113
To program post sequence events 113
To save a sequence 114
To load a stored sequence 114
To determine sequence status 114
Advanced User Guide
5
To start a sequence 114
To pause and resume a sequence
To stop a sequence 115
To abort a sequence 115
6
115
Checking for Leaks
Preparing the GC for Maintenance 118
Column and oven preparation 118
Inlet preparation 118
Detector preparation 118
Leak Check Tips
119
To Check for External Leaks
To Check for GC Leaks
120
121
Leaks in Capillary Column (Microfluidic) Fittings
122
To Perform a SS Inlet Pressure Decay Test
123
To Correct Leaks in the Split Splitless Inlet
127
To Perform a Multimode Inlet Pressure Decay Test
To Correct Leaks in the Multimode Inlet
132
To Perform a PP Inlet Pressure Decay Test
133
To Correct Leaks in the Packed Column Inlet
To Perform a COC Pressure Decay Test
137
138
To Correct Leaks in the Cool On-Column Inlet
To Perform a PTV Pressure Decay Test
To Correct Leaks in the PTV Inlet
141
142
146
To Perform a VI Pressure Decay Test
147
To Prepare the VI for a Closed System Leak Check
To Correct Leaks in the Volatiles Interface
7
150
151
Flow and Pressure Modules
About Flow and Pressure Control
Maximum operating pressure
PIDs 155
Inlet Modules
154
154
156
Detector Modules
157
Pressure Control Modules
158
Auxiliary Pressure Controllers
6
128
161
Advanced User Guide
Restrictors
162
Examples 163
1. Using an Aux epc channel to supply purge gas to a splitter
2. Using the PCM channels 163
8
163
Inlets
Using Hydrogen
Inlet Overview
167
168
Carrier Gas Flow Rates
169
About Gas Saver 170
To use gas saver 170
Pre Run and Prep Run 171
The [Prep Run] key 171
Auto Prep Run 172
About Heaters
173
About the Split/Splitless Inlet 175
Septum tightening (S/SL) 175
Standard and high-pressure versions of the S/SL inlet 175
Split/Splitless inlet split mode overview 176
Split/Splitless inlet splitless mode overview 177
The S/SL inlet pulsed split and splitless modes 178
Split/Splitless inlet split mode minimum operating pressures
Selecting the correct S/SL inlet liner 180
Vapor Volume Calculator 182
Setting parameters for the S/SL split mode 182
Selecting parameters for the S/SL splitless mode 183
Setting parameters for the S/SL splitless mode 184
Setting parameters for the S/SL pulsed modes 185
About the Multimode Inlet 186
Septum tightening (MMI) 186
Heating the MMI 187
Cooling the MMI 187
MMI split mode minimum operating pressures 188
Selecting the correct MMI liner 189
Vapor Volume Calculator 191
MMI split and pulsed split modes 191
MMI splitless and pulsed splitless modes 194
MMI solvent vent mode 201
MMI Direct Mode 209
To develop a MMI method that uses large volume injection
Advanced User Guide
179
210
7
Multiple injections with the MMI
About the Packed Column Inlet
Setting parameters 220
213
219
About the Cool On-Column Inlet 222
Setup modes of the COC inlet 223
Retention gaps 223
COC inlet temperature control 223
Setting COC inlet flows/pressures 224
Setting COC inlet parameters 225
About the PTV Inlet 226
PTV sampling heads 226
Heating the PTV inlet 227
Cooling the PTV inlet 228
PTV inlet split and pulsed split modes 228
PTV inlet splitless and pulsed splitless modes 232
PTV inlet solvent vent mode 239
To develop a PTV method that uses large volume injection
Multiple injections with the PTV inlet 250
247
About the Volatiles Interface 255
VI operating modes 256
About the VI split mode 257
About the VI splitless mode 261
About the VI direct mode 266
Preparing the Interface for Direct Sample Introduction
Disconnecting the split vent line 269
Configuring for direct mode 271
VI direct mode setpoint dependencies 271
VI direct mode initial values 271
Setting parameters for the VI direct mode 272
9
269
Columns and Oven
About the Oven
Oven safety
276
276
Configuring the Oven
277
Cryogenic Operation 278
Cryogenic setpoints 278
About Oven Temperature Programming
Programming setpoints 280
Post run 281
Oven ramp rates 281
8
280
Advanced User Guide
Setting the oven parameters for constant temperature 282
Setting the oven parameters for ramped temperature 282
About the Oven Insert
284
About Columns 285
Selecting the correct packed glass column type 285
About the column modes 285
Select a column mode 286
Setting the column parameters for constant flow or constant
pressure 287
Enter a flow or pressure program (optional) 287
Programming column pressure or flow 288
Backflushing a Column 289
Backflushing when connected to an MSD 289
Backflushing using a capillary flow technology device
Nickel Catalyst Tube 295
About the nickel catalyst tube 295
Nickel catalyst gas flows 295
Setting temperatures for the nickel catalyst tube
10
290
296
Detectors
About Makeup Gas
298
About the FID 299
How FID units are displayed in Agilent data systems and on the GC
To light the FID flame 300
To extinguish the FID flame 300
FID automatic reignition (Lit offset) 301
Recommended starting conditions for new FID methods 301
Setting parameters for FID 302
300
About the TCD 304
TCD pneumatics 306
TCD carrier, reference, and makeup gas 306
TCD gas pressures 307
Selecting reference and makeup flows for the TCD 308
Chemically active compounds reduce TCD filament life 308
Changing the TCD polarity during a run 309
Detecting hydrogen with the TCD using helium carrier gas 309
Setting parameters for the TCD 309
About the uECD 312
uECD safety and regulatory information 312
uECD warnings 313
Safety precautions when handling uECDs 315
Advanced User Guide
9
uECD gas flows 316
uECD linearity 316
uECD detector gas 316
uECD temperature 316
uECD analog output 317
Recommended starting conditions for new uECD methods
uECD makeup gas notes 317
uECD temperature programming 318
Setting parameters for the uECD 318
About the NPD 319
New NPD features and changes 319
NPD software requirements 319
NPD flows and general information 319
NPD flow, temperature, and bead recommendations
NPD required gas purity 322
Setting parameters for the NPD 323
Selecting an NPD bead type 324
Changing from a ceramic bead to a Blos bead 325
Selecting an NPD jet 325
To configure the NPD 326
Automatically adjusting NPD bead voltage 327
Setting NPD adjust offset on the clock table 328
Aborting NPD adjust offset 328
Extending the NPD bead life 328
Setting the initial bead voltage for new beads 329
Setting NPD bead voltage manually (optional) 329
About the FPD 331
FPD linearity 332
FPD Lit Offset 332
Starting Up and Shutting Down the FPD
FPD photomultiplier protection 332
FPD optical filters
332
Inlet liners for use with the FPD 333
FPD temperature considerations 333
FPD gas purity 333
FPD gas flows 333
Lighting the FPD flame 334
Setting parameters for the FPD 335
11
320
332
Valves
About Valves
The Valve Box
10
317
338
339
Advanced User Guide
Heating the valves 339
Valve temperature programming
Configuring an Aux thermal zone
Valve Control 341
The valve drivers 341
The internal valve drivers
The external valve drivers
Valve Types
339
340
341
342
343
Configuring a Valve
344
Controlling a Valve 345
From the keyboard 345
From the run or clock time tables 345
Simple valve: column selection 345
Gas sampling valve 346
Multiposition stream selection valve with sampling valve
12
347
7683B Sampler
About the 7683B Sampler
Hardware 350
Software 350
350
Setting Parameters for the ALS 351
Solvent Saver 352
Sample tray setpoints 353
Storing setpoints 353
13
Cables
About Cables and Back Panel Connectors
Back panel connectors 356
Sampler connectors 356
The AUX connector 356
Signal connectors 357
REMOTE connector 357
EVENT connector 357
BCD input connector 357
RS-232 connector 357
LAN connector 357
356
Using the Remote Start/Stop cable 358
Connecting Agilent products 358
Connecting non-Agilent products 358
Connecting Cables
Advanced User Guide
361
11
Cable Diagrams 363
Analog cable, general use 363
Remote start/stop cable 363
BCD cable 364
External event cable 365
14
GC Output Signals
About Signals
368
Signal Types 369
Value 369
Analog Signals 371
Analog zero 371
Analog range 371
Analog data rates 372
Selecting fast peaks (analog output)
373
Digital Signals 374
Digital zero 374
Baseline level shifts 374
Agilent data systems 375
Zero Init Data Files 377
Column Compensation 378
Creating a column compensation profile 379
Making a run using analog output column compensation
Making a run using digital output column compensation
Plotting a stored column compensation profile 380
Test Plot
15
379
379
381
Miscellaneous Topics
Auxiliary Devices 384
About Auxiliary Pressure Control 384
About Aux Thermal Zone Control 385
About Auxiliary Device Contacts 385
About the 24V Auxiliary Device Power Supply
About Auxiliary Columns 385
About Auxiliary Detectors 386
To Use the Stopwatch
385
387
Service Mode 388
Service Reminders 388
Other functions 389
12
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
1
Programming
Run Time Programming 14
Using run time events 14
Programming run time events 15
The run table 15
Adding events to the run table 15
Editing events in the run table 15
Deleting run time events 16
Clock Time Programming 17
Using clock time events 17
Programming clock time events 17
Adding events to the clock table 17
Editing clock time events 18
Deleting clock time events 18
User-Key Programming 19
To play back (execute) the stored keystrokes 19
To erase the stored keystrokes 19
To program a User Key 19
Agilent Technologies
13
Run Time Programming
Run time programming allows certain setpoints to change
automatically during a run as a function of the chromatographic
run time. Thus an event that is programmed to occur at
2 minutes will occur 2 minutes after every injection.
Its uses include:
• Controlling column switching or other valves
• Changing signal definition, zero, or range
• Controlling an auxiliary pressure channel
• Changing polarity of a thermal conductivity detector (TCD)
• Turning the hydrogen flow to a nitrogen- phosphorus
detector (NPD) on or off
• Pausing (freezing) and resuming a signal value
The changes are entered into a run table that specifies the
setpoint to be changed, the time for the change, and the new
value. At the end of the chromatographic run, most setpoints
changed by a run time table are returned to their original
values.
Valves can be run time programmed but are not restored to
their starting position at the end of the run. You must program
the reset operation in the run table if this action is desired. See
“From the run or clock time tables” on page 345.
Using run time events
The [Run Table] key is used to program timed events.
You can control the following events during a run.
• Valves (1- 8)
• Multiposition valve
• Signal type (see “Signal Types” on page 369)
• Analog signal zero and range
• Digital signal zero and baseline level shifts (see “Digital zero”
on page 374)
• Auxiliary pressures (1 through 9)
• TCD negative polarity (on/off)
• NPD H2 flow (on/off)
• Pausing (freezing) and resuming a signal value
14
Advanced User Guide
Programming run time events
1 Press [Run Table].
2
Press [Mode/Type] to see the available run time events.
3
Scroll to the event to be programmed. Press [Enter].
4
Enter values for the Time: and the other parameter. Press
[Enter] after each entry.
5
Press [Mode/Type] to add another event. Press [Status] to
terminate entries.
The run table
The programmed events are arranged in order of execution time
in the Run Table. This is a brief example:
RUN TABLE (1 of 3)
Time:
0.10
Valve #2
On
RUN TABLE (2 of 3)
Time:
3
Analog signal 2 range 2
RUN TABLE (3 of 3)
Time:
4.20
Valve #2
Off
Event 1 rotates a valve.
Event 2 adjusts the signal
range.
Event 3 resets Valve #2 to its
original position in preparation
for another run. Valves do not
reset automatically.
Adding events to the run table
1 To add new events to the run table, press [Mode/Type] while
on the Time: line of any entry.
2
Select the event type.
3
Set appropriate Time: and other parameters. Some require
numbers; others require [On/Yes] or [Off/No].
4
Repeat until all entries are added. Events are automatically
placed in order by execution time.
Editing events in the run table
1 Press [Run Table].
Advanced User Guide
2
Move the cursor to the event you want to change.
3
To edit the time for an event, move the cursor to the line
labeled Time:. Type the desired time and press [Enter].
4
To edit a setpoint value, scroll to the setpoint line. Press
[On/Yes] or [Off/No] or enter a numeric value for the
setpoint. Press [Enter].
15
Deleting run time events
1 Press [Run Table].
16
2
From within this table press [Delete] to delete events from
the run time table. You will be asked to confirm the deletion.
3
Press [On/Yes] to delete the current timed event; press
[Off/No] to cancel this operation.
4
To delete the entire table, press [Delete][Run Table].
Advanced User Guide
Clock Time Programming
Clock time programming allows certain setpoints to change
automatically at a specified time during a 24- hour day. Thus, an
event programmed to occur at 14:35 hours will occur at 2:35 in
the afternoon. A running analysis or sequence has precedence
over any clock table events occurring during this time. Such
events are not executed.
Possible clock time events include:
• Valve control
• Method and sequence loading
• Starting sequences
• Initiating blank and prep runs
• Column compensation changes
• Adjustments of the detector offset
Using clock time events
The Clock Table function allows you to program events to occur
during a day based on the 24- hour clock. Clock table events that
would occur during a run or sequence are ignored.
For example, the clock table could be used to make a blank run
before you even get to work in the morning.
Programming clock time events
1 Press [Clock Table].
2
Press [Mode/Type] to see the available clock time events.
3
Scroll to the parameter to be programmed.
4
Edit Time: and the setpoints for this event.
5
Press [Mode/Type] to add another event. Press [Status] to
terminate entries.
When the clock event is executed, a confirming message
appears.
Adding events to the clock table
1 Press [Clock Table].
Advanced User Guide
2
Press [Mode/Type]. When entries are added, they are
automatically ordered chronologically.
3
Select the event type.
4
Set appropriate parameters.
17
5
Repeat this process until all entries are added.
Editing clock time events
1 Press [Clock Table] to view all events programmed.
2
Scroll to the event you want to change.
3
To edit the time for an event, move the cursor to the line
labelled Time: and type the desired time.
4
To edit a setpoint value, scroll to the setpoint item. Press
[On/Yes] or [Off/No], or enter a numerical value for the
setpoint.
Deleting clock time events
1 Press [Clock Table].
2
Use [Delete] to remove events from the clock time table. You
will be asked to confirm the deletion.
3
Press [On/Yes] to delete the current timed event; press
[Off/No] to cancel this operation.
To delete the entire table, press [Delete][Clock Table].
18
Advanced User Guide
User-Key Programming
The two User Keys create macros (sets of frequently used
keystrokes) and assign them to single keys. A macro is executed
when the User Key is pressed.
The stored keystrokes may be any keys except [Start], [Prog],
[User Key 1], or [User Key 2].
This discussion assumes that you wish to program [User Key 1].
The process is the same for [User Key 2].
To program a User Key
1 Press [Prog]. Press [User Key 1].
2
Press up to 31 keys, then press [User Key 1]. The keystrokes
are stored.
To play back (execute) the stored keystrokes
Press [User Key 1].
To erase the stored keystrokes
Press [Prog][User Key 1][User Key 1]. This creates an “empty”
macro.
Advanced User Guide
19
20
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
2
Configuration
About Configuration 23
Assigning GC resources to a device 23
Setting configuration properties 24
General Topics 25
Unlock the GC Configuration 25
Ignore Ready = 25
Information displays 25
Unconfigured: 26
Oven 27
Front Inlet/Back Inlet 29
To configure the PTV or COC coolant 29
To configure the MMI coolant 31
Column # 33
To configure a single column 33
To configure multiple columns 35
Cryo Trap 40
Front Detector/Back Detector/Aux Detector/Aux Detector 2 42
Lit offset 42
To configure the FPD heaters 42
Analog out 1/Analog out 2 43
Fast peaks 43
Valve Box 44
Thermal Aux 45
To configure an MSD transfer line heater 45
To configure a nickel catalyst heater 46
To configure an AED transfer line heater 46
PCM A/PCM B/PCM C 47
Pressure aux 1,2,3/Pressure aux 4,5,6/Pressure aux 7,8,9 49
Status 50
The Ready/Not Ready status table 50
The setpoint status table 50
Agilent Technologies
21
2
Configuration
Time 51
Valve # 52
Front injector/Back injector 53
Sample tray (7683 ALS) 55
Instrument 56
22
Advanced User Guide
Configuration
2
About Configuration
Configuration is a two- part process for most GC accessory
devices that require power and/or communication resources
from the GC. In the first part of the configuration process, a
power and/or communication resource is assigned to the
device. The second part of the configuration process allows
setting of any configuration properties associated with the
device.
Assigning GC resources to a device
A hardware device requiring but not assigned GC resources is
given a mode of Unconfigured by the GC. Once you assign GC
resources to a device, the GC gives the device a mode of
Configured, allowing you to access other property settings (if
any) for the device.
To assign GC resources to a device with an Unconfigured mode:
1 Unlock the GC configuration. Press [Options], select Keyboard
& Display and press [Enter]. Scroll down to Hard Configuration
Lock and press [Off/No].
2
Press [Config] on the GC keypad and select a device from the
list, then press [Enter].
The [Config] key opens a menu similar to this:
Oven
Front inlet
Back Inlet
Column #
Front detector
Back detector
Aux detector
Aux detector 2
Analog out 1
Analog out 2
Valve Box
Thermal Aux 1
Thermal Aux 2
Thermal Aux 3
PCM A
PCM B
PCM C
Aux EPC 1,2,3
Aux EPC 4,5,6
Aux EPC 7,8,9
Advanced User Guide
23
2
Configuration
Status
Time
Valve #
2 Dimensional GC Valve
Front injector
Back injector
Sample tray
Instrument
In many cases you can move directly to the item of interest
by pressing [Config][device].
3
When the Configure Device Display opens, the cursor should
be on the Unconfigured field. Press [Mode/Type] and follow the
GC prompts to assign resources to the device.
4
After assigning resources, the GC prompts for you to power
cycle the GC. Turn the GC power switch off and then on.
When the GC starts, select the device just assigned the GC
resources for further configuration if needed. When accessed,
its mode should indicate Configured and the other configuration
properties are displayed.
Setting configuration properties
A device’s configuration properties are constant for an
instrument hardware setup unlike method settings which can
change from sample run to sample run. An example of a
configuration setting is the gas type flowing through a
pneumatic device or the operation temperate limit of a device.
To change the setting configuration properties for a Configured
device:
1 Press [Config] on the GC keypad and select a device from the
list, then press [Enter].
In many cases you can move directly to the item of interest
by pressing [Config][device].
2
24
Scroll to the device setting and change the property. This can
involve making a selection from a list using [Mode/Type],
using [On/Yes] or [Off/No], or entering a numeric value. Press
[Info] for help on changing numeric settings, or see the
section of this document describing the specific
configuration of the device.
Advanced User Guide
2
Configuration
General Topics
Unlock the GC Configuration
Accessory devices including inlets, detectors, pressure
controllers (AUX EPC and PCM), and temperature control loops
(Thermal AUX) have electrical connections to a power source
and/or the communication bus in the GC. These devices must be
assigned GC resources before they can be used. Before assigning
resources to a device, you must first unlock the GC
configuration. If you try to configure an Unconfigured device
without unlocking the GC configuration, the GC displays the
message CONFIGURATION IS LOCKED Go to Keyboard options to
unlock.
It is also necessary to unlock the GC configuration if you are
removing the GC resources from a Configured device. This action
returns the device state to Unconfigured.
To unlock the GC configuration, press [Options], select Keyboard
& Display and press [Enter]. Scroll down to Hard Configuration Lock
and press [Off/No].
The GC configuration remains unlocked until the GC is power
cycled off and on.
Ignore Ready =
The states of the various hardware elements are among the
factors that determine whether the GC is Ready for analysis.
Under some circumstances, you may not wish to have a specific
element readiness considered in the GC readiness
determination. This parameter lets you make that choice.
For example, suppose an inlet heater is defective but you don’t
plan to use that inlet today. By setting Ignore Ready = TRUE for
that inlet, you can use the rest of the GC. After the heater is
repaired, set Ignore Ready = FALSE or the run could start before
that inlet’s conditions are ready.
Information displays
Below are some examples of configuration displays:
[ EPC1 ] = (INLET) (SS) EPC #1 is used for an inlet of type
split/splitless. It is not available for other uses.
Advanced User Guide
25
2
Configuration
[ EPC3 ] = (DET-EPC) (FID)
to an FID.
EPC #3 is controlling detector gases
[ EPC6 ] = (AUX_EPC) (PCM) EPC #6 is controlling a
two- channel pressure control module.
FINLET (OK) 68 watts 21.7 This heater is connected to the front
inlet. Status = OK, meaning that it is ready for use. At the time
that the GC was turned on, the heater was drawing 68 watts and
the inlet temperature was 21.7 °C.
[ F-DET ] = (SIGNAL) (FID)
detector is type FID.
The signal board for the front
AUX 2 1 watts (No sensor) The AUX 2 heater is either not
installed or not OK.
Unconfigured:
Accessory devices requiring GC power or communication must
be assigned these GC resources before they can be used. To
make this hardware element usable, first “Unlock the GC
Configuration” on page 25 then go to the Unconfigured parameter
and press [Mode/Type] to install it. If the hardware element you
are configuring requires selection of additional parameters, the
GC asks for that selection. If no parameters are required, press
[Enter] at the GC prompt to install that element. You are
required to power the GC off and then power the GC on to
complete this configuration.
After restarting the GC, a message reminding you of this change
and its effect on the default method is displayed. If needed,
change your methods to accommodate the new hardware.
26
Advanced User Guide
2
Configuration
Oven
See “Unconfigured:” on page 26 and “Ignore Ready =” on
page 25.
Maximum temperature Sets an upper limit to the oven
temperature. Used to prevent accidental damage to columns.
The range is 70 to 450 °C.
Equilibration time The time after the oven approaches its
setpoint before the oven is declared Ready. The range is 0 to
999.99 minutes. Used to ensure that the oven contents have
stabilized before starting another run.
Cryo These setpoints control liquid carbon dioxide (CO2 or
liquid nitrogen (N2) cooling of the oven.
The cryogenic valve lets you operate the oven below ambient
temperature. Minimum attainable oven temperature depends on
the type of valve installed.
The GC senses the presence and type of cryogenic valve and
disallows setpoints if no valve is installed. When cryogenic
cooling is not needed or cryogenic coolant is not available, the
cryogenic operation should be turned off. If this is not done,
proper oven temperature control may not be possible,
particularly at temperatures near ambient.
External oven mode Isothermal internal oven and programmed
external oven used to calculate column flow.
Slow oven cool down mode On reduces the oven fan speed
during the cool down cycle.
To configure the oven
1 Press [Config][Oven].
Advanced User Guide
2
Scroll to Maximum temperature. Enter a value and press
[Enter].
3
Scroll to Equilibration time. Enter a value and press [Enter].
4
Scroll to Cryo. Press [On/Yes] or [Off/No]. If On, enter the
setpoints described in “To configure the oven for cryogenic
cooling” on page 28.
5
Scroll to External oven mode. Press [On/Yes] or [Off/No].
27
2
Configuration
6
Scroll to Slow oven cool down mode. Press [On/Yes] to run the
oven fan at reduced speed during cool down, or [Off/No] to
run it at normal speed.
To configure the oven for cryogenic cooling
All cryogenic setpoints are in the [Config][Oven] parameter list.
Cryo
[ON] enables cryogenic cooling, [OFF] disables it.
Quick cryo cool This feature is separate from Cryo. Quick cryo
cool makes the oven cool faster after a run than it would
without assistance. This feature is useful when maximum
sample throughput is necessary, however it does use more
coolant. Quick cryo cool turns off soon after the oven reaches its
setpoint and Cryo takes over, if needed.
Ambient temp The temperature in the laboratory. This setpoint
determines the temperature at which cryogenic cooling is
enabled:
• Ambient temp + 25°C, for regular cryo operation
• Ambient temp + 45°C, for Quick Cryo Cool.
Cryo timeout Cryo timeout occurs, and the oven shuts off, when
a run does not start within a specified time (10 to 120 minutes)
after the oven equilibrates. Turning cryo timeout off disables
this feature. We recommend that it be turned on because cryo
timeout conserves coolant at the end of a sequence or if
automation fails.
Cryo fault Shuts the oven down if it does not reach setpoint
temperature after 16 minutes of continuous cryo operation.
Note that this is the time to reach the setpoint, not the time to
stabilize and become ready at the setpoint. For example, with a
cool on- column inlet and cryo control in the oven track mode, it
may take the oven 20 to 30 minutes to achieve readiness.
If the temperature goes below the minimum allowed
temperature (–90°C for liquid nitrogen,–70°C for liquid CO2),
the oven will shut down.
The COC and PTV inlets must use the same cryo type as
configured for the oven.
28
Advanced User Guide
2
Configuration
Front Inlet/Back Inlet
See “Unconfigured:” on page 26 and “Ignore Ready =” on
page 25.
To configure the Gas type
The GC needs to know what carrier gas is being used.
1 Press [Config][Front Inlet] or [Config][Back Inlet].
2
Scroll to Gas type and press [Mode/Type].
3
Scroll to the gas you will use. Press [Enter].
This completes carrier gas configuration.
To configure the PTV or COC coolant
Press [Config][Front Inlet] or [Config][Back Inlet]. If the inlet has
not been configured previously, a list of available coolants is
displayed. Scroll to the desired coolant and press [Enter]. If oven
cooling is installed, your choices are restricted to the coolant
used by the oven or None.
Cryo type [Mode/Type] displays a list of available coolants.
Scroll to the desired coolant and press [Enter].
If the Cryo type selection is anything other than None, several
other parameters appear.
Cryo [On/Yes] enables cryogenic cooling of the inlet at the
specified Use cryo temperature setpoint, [Off/No] disables cooling.
Use cryo temperature This setpoint determines the temperature
at which cryogenic cooling is used continuously. The inlet uses
cryogen to achieve the initial setpoint. If the initial setpoint is
below the Use cryo temperature, cryogen is used continuously to
achieve and maintain the setpoint. Once the inlet temperature
program starts, the cryogen will be turned off when the inlet
exceeds the Use cryo temperature. If the initial setpoint is above
the Use cryo temperature, cryogen is used to cool the inlet until it
reaches the setpoint and then it is turned off. At the end of a
run, the inlet waits until the oven becomes ready before it uses
cryogen.
If the inlet is to be cooled during a run, cryogen will be used to
achieve the setpoint. This may have a negative impact on the
chromatographic performance of the oven and cause distorted
peaks.
Advanced User Guide
29
2
Configuration
Cryo timeout Use this setting to conserve cryogenic fluid. If
selected, the instrument shuts down the inlet and cryogenic
(subambient) cooling (if installed) when no run starts in the
number of minutes specified. The setpoint range is 2 to 120
minutes (default 30 minutes). Turning cryo timeout off disables
this feature. We recommend cryo timeout enabling to conserve
coolant at the end of a sequence or if automation fails. A Post
Sequence method could also be used.
Cryo fault Shuts down the inlet temperature if it does not reach
setpoint in 16 minutes of continuous cryo operation. Note that
this is the time to reach the setpoint, not the time to stabilize
and become ready at the setpoint.
Shutdown behavior
Both Cryo timeout and Cryo fault can cause cryo shutdown. If
this happens, the inlet heater is turned off and the cryo valve
closes. The GC beeps and displays a message.
The inlet heater is monitored to avoid overheating. If the heater
remains on at full power for more than 2 minutes, the heater is
shut down. The GC beeps and displays a message.
To recover from either condition, turn the GC off, then on, or
enter a new setpoint.
30
Advanced User Guide
Configuration
2
To configure the MMI coolant
Press [Config][Front Inlet] or [Config][Back Inlet]. If the inlet has
not been configured previously, a list of available coolants is
displayed. Scroll to the desired coolant and press [Enter].
Cryo type/Cooling type [Mode/Type] displays a list of available
coolants. Scroll to the desired coolant and press [Enter].
Normally, select the coolant type that matches the installed
hardware.
• N2 cryo Select if the N2 option is installed and you are using
LN2 or compressed air.
• CO2 cryo Select if the CO2 option is installed and you are
using LCO2 or compressed air.
• Compressed air Select if the N2 or CO2 option is installed and
you are only using compressed air. If Compressed air is
selected as the Cooling type, air coolant is used to cool the
inlet regardless of the Use cryo temperature setpoint during the
cooling cycle. If the inlet reaches setpoint, the air coolant is
turned off and stays off for the duration of the cooling cycle.
See Cooling the MMI for more information.
If the Cryo type selection is anything other than None, several
other parameters appear.
Cryo [On/Yes] enables cryogenic cooling of the inlet at the
specified Use cryo temperature setpoint, [Off/No] disables cooling.
Use cryo temperature If N2 cryo or CO2 cryo is selected as the
Cryo type, this setpoint determines the temperature below
which cryogenic cooling is used continuously to hold the inlet at
setpoint. Set the Use cryo temperature equal to or higher than the
inlet setpoint to cool the inlet and hold the setpoint until the
inlet temperature program exceeds the Use cryo temperature. If
the Use cryo temperature is less than the inlet setpoint, cryogen
will cool the inlet to the initial setpoint and turn off.
Cryo timeout This parameter is available with N2 cryo and CO2
cryo Cryo types. Use this setting to conserve cryogenic fluid. If
selected, the instrument shuts down the inlet and cryogenic
cooling when no run starts in the number of minutes specified.
The setpoint range is 2 to 120 minutes (default 30 minutes).
Turning cryo timeout off disables this feature. We recommend
cryo timeout enabling to conserve coolant at the end of a
sequence or if automation fails. A Post Sequence method could
also be used.
Advanced User Guide
31
2
Configuration
Cryo fault This parameter is available with N2 cryo and CO2 cryo
Cryo types. Shuts down the inlet temperature if it does not
reach setpoint in 16 minutes of continuous cryo operation. Note
that this is the time to reach the setpoint, not the time to
stabilize and become ready at the setpoint.
Shutdown behavior
Both Cryo timeout and Cryo fault can cause cryo shutdown. If
this happens, the inlet heater is turned off and the cryo valve
closes. The GC beeps and displays a message.
The inlet heater is monitored to avoid overheating. If the heater
remains on at full power for more than 2 minutes, the heater is
shut down. The GC beeps and displays a message.
To recover from either condition, turn the GC off, then on, or
enter a new setpoint.
32
Advanced User Guide
2
Configuration
Column #
Length The length, in meters, of a capillary column. Enter 0 for
a packed column or if the length is not known.
Diameter The inside diameter, in millimeters, of a capillary
column. Enter 0 for a packed column.
Film thickness The thickness, in millimeters, of the stationary
phase for capillary columns.
Inlet
Identifies the source of gas for the column.
Outlet Identifies the device into which the column effluent
flows.
Thermal zone Identifies the device that controls the
temperature of the column.
To configure a single column
You define a capillary column by entering its length, diameter,
and film thickness. You then enter the device controlling the
pressure at the Inlet (end of the column), the device controlling
the pressure at the column Outlet, and the Thermal zone that
controls its temperature.
With this information, the instrument can calculate the flow
through the column. This has great advantages when using
capillary columns because it becomes possible to:
• Enter split ratios directly and have the instrument calculate
and set the appropriate flow rates.
• Enter flow rate or head pressure or average linear velocity.
The instrument calculates the pressure needed to achieve the
flow rate or velocity, sets that, and reports all three values.
• Perform splitless injections with no need to measure gas
flows.
• Choose any column mode. If the column is not defined, your
choices are limited and vary depending on the inlet.
Advanced User Guide
33
2
Configuration
Except for the simplest configurations, such as a column
connected to a specific inlet and detector, we recommend that
you begin by making a sketch of how the column will be
connected.
1 Press [Config][Col 1] or [Config][Col 2], or press [Config][Aux
Col #] and enter the number of the column to be configured.
2
Scroll to the Length line, type the column length, in meters,
followed by [Enter].
3
Scroll to Diameter, type the column inside diameter in
microns, followed by [Enter].
4
Scroll to Film thickness, type the film thickness in microns,
followed by [Enter]. The column is now defined.
If you do not know the column dimensions—they are usually
supplied with the column—or if you do not wish to use the GC
calculating features, enter 0 for either Length or Diameter. The
column will be not defined.
5
Scroll to Inlet. Press [Mode/Type] to select a gas pressure
control device for this end of the column. Selections include
the installed GC inlets, and installed Aux and PCM channels.
Select the appropriate gas pressure control device and press
[Enter].
6
Scroll to Outlet. Press [Mode/Type] to select a gas pressure
control device for this end of the column. Selections include
the installed Aux and PCM channels, and detectors. When a
detector is selected, the outlet end of the column is
controlled at 0 psig for the FID, TCD, FPD, NPD, and uECD
or vacuum for the MSD.
Select the appropriate gas pressure control device and press
[Enter].
7
Scroll to Thermal zone. Press [Mode/Type] to see the available
choices. In most cases this will be GC oven, but you may have
an MSD transfer line heated by an auxiliary zone, valves in a
separately- heated valve box or other configurations.
Select the appropriate Thermal zone and press [Enter].
This completes configuration for a single capillary column.
Additional notes on column configuration
Packed columns should be configured as column not defined. To
do this, enter 0 for either column length or column diameter.
34
Advanced User Guide
2
Configuration
You should check configurations for all columns to verify that
they specify the correct pressure control device at each end. The
GC uses this information to determine the flow path of the
carrier gas. Only configure columns that are in current use in
your GC’s carrier gas flow path. Unused columns configured
with the same pressure control device as a column in the
current flow path cause incorrect flow results.
It is possible, and sometimes appropriate, to configure both
installed columns to the same inlet.
When splitters or unions exist in the carrier gas flow path,
without a GC’s pressure control device monitoring the common
junction point, the individual column flows cannot be
controlled directly by the GC. The GC can only control the inlet
pressure of the upstream column whose inlet end is attached to
a GC’s pressure control device. A column flow calculator
available from Agilent, and provided with Agilent capillary flow
devices, is used for determining pressures and flows at this type
of junction.
Some pneumatic setpoints change with oven temperature
because of changes in column resistance and in gas viscosity.
This may confuse users who observe pneumatics setpoints
changing when their oven temperature changes. However, the
flow condition in the column remains as specified by the
column mode (constant flow or pressure, ramped flow or
pressure) and the initial setpoint values.
To configure multiple columns
To configure multiple columns, repeat the procedure above for
each column.
These are the available choices for Inlet, Outlet, and Thermal zone.
Some will not appear on your GC if the specific hardware is not
installed.
Table 1
Advanced User Guide
Choices for column configuration
Inlet
Outlet
Thermal zone
Front inlet
Front detector
GC oven
Back inlet
Back detector
Auxiliary oven
Aux# 1 through 9
MSD
Aux thermal zone 1
PCM A, B, and C
Aux detector
Aux thermal zone 2
Aux PCM A, B, and C
Aux 1 through 9
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2
Configuration
Table 1
Choices for column configuration (continued)
Inlet
Outlet
Unspecified
PCM A, B, and C
Thermal zone
Aux PCM A, B, and C
Front inlet
Back inlet
Other
Inlets and outlets
The pressure control devices at the inlet and outlet ends of a
column, or series of columns in a flow path, control its gas flow.
The pressure control device is physically attached to the column
through a connection to a GC inlet, a valve, a splitter, a union, or
other device.
Table 2
Column inlet end
If the column gas flow source is:
Choose:
An inlet (SS, PP, COC, MMI, PTV, VI, or other) with electronic The inlet.
pressure control
A valve, such as gas sampling
The auxiliary (Aux PCM) or pneumatics (PCM) control
module channel that provides gas flow during the inject
cycle.
A splitter with an EPC makeup gas supply
The Aux PCM or EPC channel that provides the makeup gas
A device with a manual pressure controller
Unknown
Similar considerations apply for the column outlet end. When a
column exits to a splitter, select the GC’s pressure control
source attached to the same splitter.
Table 3
Column outlet end
If the column exhausts into
Choose:
A detector
The detector.
A splitter with a makeup gas supply
The Aux PCM or EPC channel that provides makeup gas
flow to the splitter.
A device with a manual pressure controller
Unknown
36
Advanced User Guide
2
Configuration
A simple example
An analytical column is attached at its inlet end to a
spit/splitless inlet located at the front of the GC and the column
outlet is attached to an FID located at the front detector
position.
Table 4
Column
Analytical column
Inlet
Analytical column Front split/splitless
Outlet
Thermal zone
Front FID
GC oven
Since only a single column is configured, the GC determines
that it controls the inlet pressure to the column by setting the
front inlet pressure and the outlet pressure is always
atmospheric. The GC can calculate a pressure for the front inlet
that can exactly overcome the resistance to flow presented by
this column at any point during a run.
Slightly more complex example
A precolumn is followed by a AUX 1 pressure controlled splitter
and two analytical columns. This requires three column
descriptions.
Table 5
Precolumn split to two analytical columns
Column
Inlet
Outlet
Thermal zone
1 - Precolumn
Front inlet
AUX 1
GC oven
2 - Analytical column AUX 1
Front detector
GC oven
3 - Analytical column AUX 1
Back detector
GC oven
The GC can calculate the flow through the precolumn using the
precolumns physical properties to calculate the column’s
resistance to flow, along with the front inlet pressure and the
AUX 1 pressure. Your analytical method can set this flow
directly for the precolumn.
For the flow in the two parallel analytical columns 1 and 2, the
GC can use the column’s physical properties to calculate the
split flow through each individual column, at a given AUX 1
pressure, with both columns exiting to atmospheric pressure.
Your analytical method can only set the flow for the lowest
numbered column in a split , analytical column 2. If you try to
set the flow for column #3, it will be ignored and the flow for
column #2 will be used.
Advanced User Guide
37
2
Configuration
If other columns are currently defined, they may not use AUX 1,
Front inlet, Front detector, or Back detector in their
configuration.
Complicated example
The inlet feeds the analytical column which ends at a three- way
splitter. The splitter has the column effluent and makeup gas
coming in, and transfer lines (non- coated columns) to three
different detectors. This is a case where a sketch is necessary.
Split/splitless inlet
Aux EPC
µECD
FPD
0.507 m x 0.10 mm x 0 µm
MSD
0.532 m x 0.18 mm x 0 µm
1.444 m x 0.18 mm x 0 µm
30 m x 0.25 mm x 0.25 µm HP-MS5
Table 6
Splitter with makeup and multiple detectors
Column
Inlet
Outlet
Thermal zone
1 - 30 m × 0.25 mm × 0.25 µm
Front inlet
Aux PCM 1
GC oven
2 - 1.444 m × 0.18 mm × 0 µm
Aux PCM 1
MSD
GC oven
3 - 0.507 m × 0.10 mm × 0 µm
Aux PCM 1
Front detector
GC oven
4 - 0.532 m × 0.18 mm × 0 µm
Aux PCM 1
Back detector
GC oven
The oven was chosen for the MSD line since most of it is in the
oven.
As in the previous examples, your analytical method can control
the flow of column # 1 which has a GC pressure controlled inlet
and outlet.
38
Advanced User Guide
Configuration
2
The flows to the three detectors are based on the pressure
drops through the capillaries and their resistance to flow. An
Agilent flow calculator provided with the capillary flow splitter
device is used to size the length and diameter of these capillary
sections to obtain the desired split ratios.
Your analytical method can set the flow or pressure for
column # 2, the lowest numbered column in the split. Use the
value obtained from the Agilent flow calculator for this setpoint
in your method.
Advanced User Guide
39
2
Configuration
Cryo Trap
This discussion assumes that the trap is mounted in position B,
that you use liquid nitrogen coolant and control the trap with
Thermal Aux 1.
Configuration is in several parts:
• Configure the trap to the GC
• Configure a heater to the cryo trap.
• Configure the coolant.
• Configure the user- configurable heater.
• Reboot the GC.
Configure the cryo trap to the GC
1 Press [Config], then [Aux Temp #] and select Thermal Aux 1.
Press [Enter].
2
Press [Mode/Type]. Scroll to Install BINLET with BV Cryo and
press [Enter].
3
Press [Options], select Communications, and press [Enter].
Select Reboot GC and press [On/Yes] twice.
This informs the GC that a cryo trap is installed at position B.
Configure a heater to the cryo trap
1 Press [Config], then [Aux Temp #], select Thermal Aux 1 and
press [Enter]. Select Auxiliary Type: Unknown and press
[Mode/Type]. Select User Configurable Heater and press [Enter].
2
Press [Options], select Communications, and press [Enter].
Select Reboot GC and press [On/Yes] twice.
This informs the GC that the heater parameters will be supplied
by the user.
Configure the coolant
The GC can handle only one type of coolant. If the coolant has
already been specified for some other device, then that same
coolant must be specified here.
1 Press [Config], then [Aux Temp #].
40
2
Select Thermal Aux 1 and press [Enter].
3
Scroll to Cryo Type (Valve BV).
Advanced User Guide
2
Configuration
If the value is not N2, press [Mode/Type], select N2 Cryo, press
[Enter] and then [Clear].
This tells the GC what coolant will be used.
Configure the user-configurable heater
Many of the following steps tell you to reboot the GC. Ignore
these requests by pressing [Clear]. Do not reboot until
specifically told to do so in these instructions.
1 Press [Config] and select Aux 1. Press [Enter].
2
Enter the following control values. Press [Enter], then [Clear]
after each one.
a Proportional Gain—5.30
b Integral Time—10
c Derivative Time—1.00
d Mass (Watt- sec/deg)—18
e Power (Watts)—To find the watts to set here, scroll to Back
Inlet Status (BINLET). Note the watts value and enter it for
this parameter.
f
Cryo Control Mode—Press [Mode/Type]. The first line
should already be PTV. Select Cryo Trap.
g Zone Control mode—Press [Mode/Type] and select PTV.
h Sensor—Press [Mode/Type] and select Thermocouple.
i
Maximum Setpoint—400
j
Maximum Programming Rate—720
Reboot the GC
Press [Options], select Communications, and press [Enter]. Select
Reboot GC and press [On/Yes] twice.
Advanced User Guide
41
2
Configuration
Front Detector/Back Detector/Aux Detector/Aux Detector 2
See Ignore Ready = and “Unconfigured:” on page 26.
To configure the makeup/reference gas
The makeup gas line of your detector parameter list changes
depending on your instrument configuration.
If you have an inlet with the column not defined, the makeup
flow is constant. If you are operating with column defined, you
have a choice of two makeup gas modes. See “About Makeup
Gas” on page 298 for details.
1 Press [Config][device], where [device] is one of the following:
• [Front Det]
• [Back Det]
• [Aux detector 1]
• [Aux detector 2]
2
Scroll to Makeup gas type (or Makeup/reference gas type) and
press [Mode/Type].
3
Scroll to the correct gas and press [Enter].
Lit offset
The GC monitors the difference between the detector output
with the flame lit and the output when the flame is not lit. If
this difference falls below the setpoint, the GC assumes that the
flame has gone out and tries to reignite it. See “FID automatic
reignition (Lit offset)” on page 301 for details.
To configure the FPD heaters
The flame photometric detector (FPD) uses two heaters, one in
the base and one near the combustion chamber. When
configuring the FPD heaters, select Install Detector 2 htr rather
than the default Install Detector (FPD).
42
Advanced User Guide
Configuration
2
Analog out 1/Analog out 2
Fast peaks
The GC allows you to output analog data at two speeds. The
faster speed—to be used only with the FID, FPD, and
NPD—allows minimum peak widths of 0.004 minutes (8 Hz
bandwidth), while the standard speed—which can be used with
all detectors— allows minimum peak widths of 0.01 minutes (3.0
Hz bandwidth).
To use fast peaks:
1 Press [Config][Analog out 1] or [Config][Analog out 2].
2
Scroll to Fast peaks and press [On/Yes].
The fast peaks feature does not apply to digital output.
If you are using the fast peaks feature, your integrator must be fast
enough to process data coming from the GC. Integrator bandwidth
should be at least 15 Hz.
Advanced User Guide
43
2
Configuration
Valve Box
See “Unconfigured:” on page 26 and “Ignore Ready =” on
page 25.
The valve box mounts on top of the column oven. It may contain
up to four valves mounted on heated blocks. Each block can
accommodate two valves.
Valve positions on the blocks are numbered. We suggest that
valves be installed in the blocks in numeric order.
All heated valves in a valve box are controlled by the same
temperature setpoint.
To assign a GC power source to a valve box heater
1 Unlock the GC configuration, press the [Options] key, select
Keyboard & Display and press the [Enter] key. Scroll down to
Hard Configuration Lock and press the [off] button.
2
Press [Config], scroll to Valve Box and press [Enter].
3
With Unconfigured selected, press [Mode/type], select one of
the following and press [Enter].
• Install heater A1 - for a valve box containing a single heater
plugged into the connector labeled A1 on the valve box
bracket.
• Install Heater A2 - for a valve box containing a single heater
plugged into the connector labeled A2 on the valve box
bracket.
• Install 2 htr A1 & A2 - for a valve box containing two heaters
plugged into the connectors labeled AI and A2 on the
valve box bracket.
The valve box bracket is located inside the GC right side
electrical compartment in the upper right location.
4
When prompted by the GC, turn the power off then on again.
This completes the configuration of the valve box. To set the
valve box temperature for your method press the [valve #] key,
and scroll to Valve Box.
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Advanced User Guide
2
Configuration
Thermal Aux
See “Unconfigured:” on page 26 and “Ignore Ready =” on
page 25.
The auxiliary thermal controllers provide up to three channels
of temperature control. These controllers are labeled Thermal
Aux 1, Thermal Aux 2, and Thermal Aux 3.
To assign a GC power source to an Aux thermal zone
This procedure assigns a the heater power source from heater
plug A1 or A2 to Thermal Aux 1, Thermal Aux 2, or Thermal
Aux 3 temperature control zones.
1 Unlock the GC configuration, press [Options], select Keyboard
& Display and press [Enter]. Scroll down to Hard Configuration
Lock and press [Off/No].
2
Press [Config][Aux Temp #] and scroll to Thermal Aux 1, Thermal
Aux 2, or Thermal Aux 3 and press [Enter].
3
With Unconfigured selected, press [Mode/Type], and select:
• Install Heater A1 if the heated device is plugged into the
valve box bracket plug labeled A1.
• Install Heater A2 if the heated device is plugged into the
valve box bracket plug labeled A2.
4
Press [Enter] after making selection.
5
When prompted by the GC, turn the power off then on again.
To configure an MSD transfer line heater
1 Check that a power source for the MSD heater was assigned.
See “To assign a GC power source to an Aux thermal zone” on
page 45.
Advanced User Guide
2
Press [Config][Aux Temp #] and scroll to Thermal Aux 1, Thermal
Aux 2, or Thermal Aux 3 depending on where the MSD heater
was assigned, and press [Enter].
3
Scroll to Auxiliary type, press [Mode/Type], scroll to and select
the MSD transfer line, and press [Enter].
45
2
Configuration
To configure a nickel catalyst heater
1 Check that a power source for the Nickel Catalyst heater was
assigned. See “To assign a GC power source to an Aux
thermal zone” on page 45.
2
Press [Config][Aux Temp #] and scroll to Thermal Aux 1, Thermal
Aux 2, or Thermal Aux 3 depending on where the Nickel
Catalyst heater was assigned, and press [Enter].
3
Scroll to Auxiliary type, press [Mode/Type], scroll to and select
Nickel catalyst, and press [Enter].
To configure an AED transfer line heater
1 Check that a power source for the AED transfer line heater
was assigned. See “To assign a GC power source to an Aux
thermal zone” on page 45.
46
2
Press [Config][Aux Temp #] and scroll to Thermal Aux 1, Thermal
Aux 2, or Thermal Aux 3 depending on where the AED transfer
line heater was assigned, and press [Enter].
3
Scroll to Auxiliary type, press [Mode/Type], scroll to and select
the AED transfer line, and press [Enter].
Advanced User Guide
2
Configuration
PCM A/PCM B/PCM C
See “Unconfigured:” on page 26 and “Ignore Ready =” on
page 25.
A pressure control module (PCM) provides two channels of gas
control.
Channel 1 is a simple forward- pressure regulator that
maintains a constant pressure at its output. With a fixed
downstream restrictor, it provides constant flow.
Channel 2 is more versatile. With the normal flow direction (in
at the threaded connector, out via the coiled tubing), it is
similar to channel 1. However with the flow direction reversed
(some extra fittings will be needed), it becomes a back- pressure
regulator that maintains a constant pressure at its inlet.
Thus channel 2 (reversed) behaves as a controlled leak. If the
inlet pressure drops below setpoint, the regulator closes down.
If inlet pressure rises above setpoint, the regulator bleeds off
gas until the pressure returns to setpoint.
To assign a GC communication source to a PCM
1 Unlock the GC configuration, press [Options], select Keyboard
& Display and press [Enter]. Scroll down to Hard Configuration
Lock and press [Off/No].
2
Press [Config][Aux EPC #], scroll to a PCMx and press [Enter].
3
With Unconfigured selected, press [Mode/Type], select Install
EPCx and press [Enter].
4
When prompted by the GC, turn the power off then on again.
To configure the other parameters on this PCM, see To
configure a PCM.
To configure a PCM
1 Press [Config][Aux EPC #], scroll to the PCMx and press [Enter].
2
Scroll to Gas type, press [Mode/Type], make a selection and
press [Enter].
This completes configuration for Channel 1. The rest of the
entries refer to Channel 2.
3
Advanced User Guide
Scroll to Aux gas type, press [Mode/Type], make a selection
and press [Enter].
47
2
Configuration
4
Scroll to Aux Mode:, press [Mode/Type], select one of the
following and press [Enter]:
• Forward Pressure Control - Aux channel
• Back Pressure Control- Aux channel
For a definition of these terms see “Pressure Control
Modules” on page 158.
The pressure control mode for the main channel is set by
pressing [Aux EPC #]. Select Mode: , press [Mode/Type], select the
mode and press [Enter].
48
Advanced User Guide
2
Configuration
Pressure aux 1,2,3/Pressure aux 4,5,6/Pressure aux 7,8,9
See Ignore Ready = and “Unconfigured:” on page 26.
An auxiliary pressure controller provides three channels of
forward- pressure regulation. Three modules can be installed
for a total of nine channels.
The numbering of the channels depends on where the controller
is installed. See “Auxiliary Pressure Controllers” on page 161
for details. Within a single module, channels are numbered from
left to right (as seen from the back of the GC) and are labeled on
the AUX EPC module.
To assign a GC communication source to an Aux EPC
1 Unlock the GC configuration, press [Options], select Keyboard
& Display and press [Enter]. Scroll down to Hard Configuration
Lock and press [Off/No].
2
Press [Config][Aux EPC #], select Aux EPC 1,2,3 or Aux EPC 4,5,6 or
Aux EPC 7,8,9 and press [Enter].
3
With Unconfigured selected, press [Mode/Type], select Install
EPCx and press [Enter].
4
When prompted by the GC, turn the power off then on again.
To configure the other parameters on this EPC, see To configure
an auxiliary pressure channel.
To configure an auxiliary pressure channel
1 Press [Config][Aux EPC #], select Aux EPC 1,2,3 or Aux EPC 4,5,6 or
Aux EPC 7,8,9 and press [Enter].
Advanced User Guide
2
Select Chan x Gas type, press [Mode/Type], select the gas that is
plumbed to the channel and press [Enter].
3
If necessary, repeat the above step for the other two
channels on this EPC module.
49
2
Configuration
Status
The [Status] key has two tables associated with it. You switch
between them by pressing the key.
The Ready/Not Ready status table
This table lists parameters that are Not Ready or gives you a
Ready for Injection display. If there are any faults, warnings, or
method mismatches present, they are displayed here.
The setpoint status table
This table lists setpoints compiled from the active parameter
lists on the instrument. This is a quick way to view active
setpoints during a run without having to open multiple lists.
To configure the setpoint status table
You can change the order of the list. You might want the three
most important setpoints to appear in the window when you
open the table.
1 Press [Config][Status].
50
2
Scroll to the setpoint that should appear first and press
[Enter]. This setpoint will now appear at the top of the list.
3
Scroll to the setpoint that should appear second and press
[Enter]. This setpoint will now be the second item on the list.
4
And so on, until the list is in the order you wish.
Advanced User Guide
2
Configuration
Time
Press [Time] to open this function. The first line always displays
the current date and time, and the last line always displays a
stopwatch. The two middle lines vary:
Between runs
During a run
Show last and next (calculated) run times.
Show time elapsed and time remaining in the run.
During Post Run
time.
Show last run time and remaining Post Run
To set time and date
1 Press [Config][Time].
2
Select Time zone (hhmm) and enter the local time offset from
GMT using a 24 hour format.
3
Select Time (hhmm) and enter the local time.
4
Select Date (ddmmyy) and enter the date.
To use the stopwatch
1 Press [Time].
Advanced User Guide
2
Scroll to the time= line.
3
To begin the timed period press [Enter].
4
To stop the timed period press [Enter].
5
Press [Clear] to reset the stopwatch.
51
2
Configuration
Valve #
Up to 4 valves can be mounted in a temperature- controlled
valve box and are normally wired to the valve box bracket V1
through V4 plugs, located inside the electrical compartment.
Additional valves or other devices (4 through 8) can be wired
using the plug labeled EVENT on the back of the GC.
To configure a valve
1 Press [Config][Valve #] and enter the number (1 to 8) of the
valve you are configuring. The current valve type is
displayed.
2
To change the valve type, press [Mode/Type], select the new
valve type, and press [Enter].
Valve types
• Sampling Two- position (load and inject) valve. In load
position, an external sample stream flows through an
attached (gas sampling) or internal (liquid sampling) loop
and out to waste. In inject position, the filled sampling loop
is inserted into the carrier gas stream. When the valve
switches from Load to Inject, a run starts if one is not
already in progress. See the example in “Gas sampling valve”
on page 346.
• Switching Two- position valve with four, six, or more ports.
These are general- purpose valves used for such tasks as
column selection, column isolation, and many others. For an
example of valve control, see “Simple valve: column
selection” on page 345.
• Multiposition Also called a stream selection valve. It selects
one from a number of gas streams and feeds it to a sampling
valve. The actuator may be ratchet- (advances the valve one
position each time it is activated) or motor- driven. An
example that combines a stream selection valve with a gas
sampling valve is on page 347.
• Remote start Available selection when configuring valve #7
or #8 only. Use this selection when wires controlling an
external device are attached to an internal pair of contacts
controlled by the GC.
• Other Something else.
• Not installed Self- explanatory.
52
Advanced User Guide
2
Configuration
Front injector/Back injector
The GC supports two models of samplers.
For the 7693A samplers, the GC recognizes which injector is
plugged into which connector, INJ1 or INJ2. No configuration is
needed. To move an injector from one inlet to another requires
no settings: the GC detects the injector position.
To configure the 7693A sampler system, see the 7693A
Installation, Operation, and Maintenance manual.
For the 7683 series samplers, normally the front inlet’s injector
is plugged into the connection on the rear of the GC labeled
INJ1. The rear inlet’s injector is plugged into the connection on
the rear of the GC labeled INJ2.
When a GC shares a single 7683 injector between two inlets, the
injector is moved from one inlet to the other and the injector’s
plug- in on the rear of the GC is switched.
To move the 7683 injector from one inlet on the GC to another
without changing the injector’s plug- in, use the Front/Back tower
parameter.
Solvent Wash Mode (7683 ALS)
This section applies to the 7683 ALS system. To configure the
7693A sampler system, see the 7693A Installation, Operation,
and Maintenance manual.
Depending upon the installed injector and turret, these
parameters may be available to configure multiple solvent wash
bottles usage. If necessary, refer to your injector user
documentation for details.
A, B—Use solvent bottle A if injector uses solvent A washes and
solvent bottle B if injector uses solvent B washes.
A-A2, B-B2—Use solvent bottles A and A2 if injector uses solvent
A washes and solvent bottles B and B2 if injector uses solvent B
washes. The injector alternates between both bottles.
A-A3, B-B3—Use solvent bottles A, A2, and A3 if injector uses
solvent A washes and solvent bottles B, B2, and B3 if injector
uses solvent B washes. The injector alternates between all
bottles.
Advanced User Guide
53
2
Configuration
To configure an injector (7683 ALS)
This section applies to the 7683 ALS system. To configure the
7693A sampler system, see the 7693A Installation, Operation,
and Maintenance manual.
1 Press [Config][Front Injector] or [Config][Back Injector].
54
2
Scroll to Front/Back tower.
3
Press [Off/No] to change the present tower position from
INJ1 to INJ2 or from INJ2 to INJ1.
4
If the installed turret has locations for multiple solvent
bottles, scroll to Wash Mode, press [Mode/Type], and then
select 1, 2, or 3 bottles for each solvent and press [Enter].
5
Scroll to [Syringe size]. Enter the size of the syringe that is
installed and press [Enter].
Advanced User Guide
Configuration
2
Sample tray (7683 ALS)
This section applies to the 7683 ALS system. To configure the
7693A sampler system, see the 7693A Installation, Operation,
and Maintenance manual.
1 Press [Config][Sample Tray].
2
If the vial gripper is touching vials either too high or too low
for reliable pickup, scroll to Grip offset and press [Mode/Type]
to select:
• Up to increase the gripper arm pickup height
• Default
• Down to decrease the gripper arm pickup height
3
Scroll to Bar Code Reader.
4
Press [On/Yes] or [Off/No] to control the following bar code
setpoints:
• Enable 3 of 9—encodes both letters and numbers, plus a few
punctuation marks, and message length can be varied to
suit both the amount of data to be encoded and the space
available
• Enable 2 of 5—restricted to numbers but does allow variable
message length
• Enable UPC code—restricted to numbers- only with fixed
message length
• Enable checksum—verifies that the checksum in the
message matches the checksum calculated from the
message characters, but does not include the checksum
character in the returned message
5
Advanced User Guide
Enter 3 as the BCR Position when the reader is installed in the
front of the tray. Positions 1–19 are available.
55
2
Configuration
Instrument
1 Press [Config]. Scroll to Instrument and press [Enter].
2
Scroll to Serial #. Enter a serial number and press [Enter].
This function can only be done by Agilent service personnel.
3
Scroll to Auto prep run. Press [On/Yes] to enable Auto prep run,
[Off/No] to disable it. See “Pre Run and Prep Run” on
page 171 for details.
4
Scroll to Zero Init Data Files.
• Press [On/Yes] to enable it. When it is On, the GC
immediately begins to subtract the current detector
output from all future values. This applies only to digital
output, and is useful when a non- Agilent data system has
problems with baseline data that is non- zero.
• Press [Off/No] to disable it. This is appropriate for all
Agilent data systems.
56
5
Front inlet type: and Back inlet type: are both information
displays. The values are determined by the type of flow
modules installed.
6
The Oven line displays the GC power configuration.
7
Press [Clear] to return to the Config menu or any other
function to end.
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
3
Options
About Options 58
Calibration 59
Maintaining EPC calibration—inlets, detectors, PCM, and AUX 59
Auto zero septum purge 60
Auto flow zero 59
Zero conditions 60
Zero intervals 60
To zero a specific flow or pressure sensor 60
To zero all pressure sensors in all modules 61
Column calibration 61
Communication 65
Configuring the IP address for the GC 65
Keyboard and Display 66
Agilent Technologies
57
3
Options
About Options
The [Options] key is used for a group of functions that are
usually set on installation and seldom changed afterward. It
accesses this menu:
Calibration
Communication
Keyboard and Display
58
Advanced User Guide
Options
3
Calibration
Press [Calibration] to list the parameters that can be calibrated.
These include:
• Inlets
• Detectors
• ALS
• Columns
• Oven
• Atmospheric pressure
In general, you will only need to calibrate the EPC modules and
capillary columns. ALS, oven, and atmospheric pressure
calibration should only be performed be trained service
personnel.
The calibration displays are discussed in the Agilent 7890A
Service Manual.
Maintaining EPC calibration—inlets, detectors, PCM, and AUX
The EPC gas control modules contain flow and/or pressure
sensors that are calibrated at the factory. Sensitivity (slope of
the curve) is quite stable, but zero offset requires periodic
updating.
Flow sensors
The split/splitless and purged packed inlet modules use flow
sensors. If the Auto flow zero feature (see page 59) is on, they are
zeroed automatically after each run. This is the recommended
way. They can also be zeroed manually—see “To zero a specific
flow or pressure sensor.
Pressure sensors
All EPC control modules use pressure sensors. They can be
zeroed as a group or individually. There is no automatic zero for
pressure sensors.
Auto flow zero
A useful calibration option is Auto flow zero. When it is On, after
the end of a run the GC shuts down the flow of gases to an inlet,
waits for the flow to drop to zero, measures and stores the flow
Advanced User Guide
59
3
Options
sensor output, and turns the gas back on. This takes about two
seconds. The zero offset is used to correct future flow
measurements.
To activate this, select Calibration on the Options menu, then
choose either Front inlet or Back inlet, press [Enter], and turn Auto
flow zero on.
Auto zero septum purge
This is similar to Auto flow zero, but is for the septum purge flow.
Zero conditions
Flow sensors are zeroed with the carrier gas connected and
flowing.
Pressure sensors are zeroed with the supply gas line
disconnected from the gas control module.
Zero intervals
Table 7
Flow and Pressure Sensor Zero Intervals
Sensor type
Module type
Zero interval
Flow
All
Use Auto flow zero and/or
Auto zero septum purge
Pressure
Inlets
Packed columns
Every 12 months
Small capillary columns
(id 0.32 mm or less)
Every 12 months
Large capillary columns
(id > 0.32 mm)
At 3 months, at 6 months,
then every 12 months
Auxiliary channels
Every 12 months
Detector gases
Every 12 months
To zero a specific flow or pressure sensor
1 Press [Options], scroll to Calibration, and press [Enter].
2
Scroll to the module to be zeroed and press [Enter].
3
Scroll to a zero line and press [Info]. The GC will remind you
of the conditions necessary for zeroing that specific sensor.
Flow sensors. Verify that the gas is connected and flowing
(turned on).
60
Advanced User Guide
Options
3
Pressure sensors. Disconnect the gas supply line at the back
of the GC. Turning it off is not adequate; the valve may leak.
4
Press [On/Yes] to zero or [Clear] to cancel.
To zero all pressure sensors in all modules
1 Press [Service Mode], scroll to Diagnostics, and press [Enter].
2
Scroll to Electronics and press [Enter].
3
Scroll to Pneumatics and press [Enter].
4
Scroll to Zero all pressure sensors and press [Info]. The GC will
remind you that all gas supplies must be disconnected at the
back panel. Turning them off is not adequate; the valves may
leak.
5
Press [On/Yes] to zero or [Clear] to cancel.
Column calibration
As you use a capillary column, you may occasionally trim off
portions, changing the column length. If measuring the actual
length is impractical, and if you are using EPC with a defined
column, you can use an internal calibration routine to estimate
the actual column length. Similarly, if you do not know the
column internal diameter or believe it is inaccurate, you can
estimate the diameter from related measurements.
Before you can calibrate the column, make sure that:
• You are using a capillary column
• The column is defined
• There are no oven ramps
• The column gas source (usually the inlet) is On and non- zero
Also note that column calibration fails if the calculated column
length correction is > 5 m, or if the calculated diameter
correction is > 20 μm.
Calibration modes
There are three ways to calibrate the column length and/or
diameter:
• Calibrate using an actual measured column flow rate
• Calibrate using an unretained peak time (elution time)
• Calibrate both length and diameter using flow rate and
elution time
Advanced User Guide
61
3
Options
CAUTION
When you measure the column flow rate, be sure to convert the
measurement to normal temperature and pressure if your
measurement device does not report data at NTP. If you enter
uncorrected data, the calibration will be wrong.
To estimate the actual column length or diameter from an elution
time
1 Set oven ramp 1 to 0.00, then verify that the column is
defined.
2
Perform a run using an unretained compound and record
the elution time.
3
Press [Options], scroll to Calibration and press [Enter].
4
From the calibration list, select the column and press [Enter].
The GC displays the current calibration mode for the
column.
5
To recalibrate or to change calibration mode, press
[Mode/Type] to see the column calibration mode menu.
6
Scroll to Length or Diameter and press [Enter]. The following
choices appear:
• Mode
• Measured flow
• Unretained peak
• Calculated length or Calculated diameter
• Not calibrated
7
Scroll to Unretained peak and enter the actual elution time
from the run performed above.
8
When you press [Enter], the GC will estimate the column
length or diameter based on the elution time input and will
now use that data for all calculations.
To estimate the actual column length or diameter from the
measured flow rate
1 Set oven ramp 1 to 0.00, then verify that the column is
defined.
62
2
Set the oven, inlet, and detectors temperatures to 35 °C and
allow them to cool to room temperature.
3
Remove the column from the detector.
Advanced User Guide
3
Options
CAUTION
When you measure the column flow rate, be sure to convert the
measurement to normal temperature and pressure if your
measurement device does not report data at NTP. If you enter
uncorrected data, the calibration will be wrong.
4
Measure the actual flow rate through the column using a
bubble meter. Record the value. Reinstall the column.
5
Press [Options], scroll to Calibration and press [Enter].
6
From the calibration list, select the column and press [Enter].
The GC displays the current calibration mode for the
column.
7
To recalibrate or to change calibration mode, press
[Mode/Type] to see the column calibration mode menu.
8
Scroll to Length or Diameter and press [Enter]. The following
choices appear:
• Mode
• Measured flow
• Unretained peak
• Calculated length or Calculated diameter
• Not calibrated
9
Scroll to Measured flow and enter the corrected column flow
rate (in mL•min) from the run performed above.
10 When you press [Enter], the GC will estimate the column
length or diameter based on the elution time input and will
now use that data for all calculations.
To estimate the actual column length and diameter
1 Set oven ramp 1 to 0.00, then verify that the column is
defined.
Advanced User Guide
2
Perform a run using an unretained compound and record
the elution time.
3
Set the oven, inlet, and detectors temperatures to 35 °C and
allow them to cool to room temperature.
4
Remove the column from the detector.
63
3
Options
CAUTION
When you measure the column flow rate, be sure to convert the
measurement to normal temperature and pressure if your
measurement device does not report data at NTP. If you enter
uncorrected data, the calibration will be wrong.
5
Measure the actual flow rate through the column using a
bubble meter. Record the value. Reinstall the column.
6
Press [Options], scroll to Calibration and press [Enter].
7
From the calibration list, select the column and press [Enter].
The GC displays the current calibration mode for the
column.
8
To recalibrate or to change calibration mode, press
[Mode/Type] to see the column calibration mode menu.
9
Scroll to Length & diameter and press [Enter]. The following
choices appear:
• Mode
• Measured flow
• Unretained peak
• Calculated length
• Calculated diameter
• Not calibrated
10 Scroll to Measured flow and enter the corrected column flow
rate (in mL•min) from the run performed above.
11 Scroll to Unretained peak and enter the actual elution time
from the run performed above.
12 When you press [Enter], the GC will estimate the column
length or diameter based on the elution time input and will
now use that data for all calculations.
64
Advanced User Guide
3
Options
Communication
Configuring the IP address for the GC
For network (LAN) operation, the GC needs an IP address. It
can get this from a DHCP server, or it can be entered directly
from the keyboard. In either case, see your LAN administrator.
To use a DHCP server
1 Press [Options]. Scroll to Communications and press [Enter].
2
Scroll to Enable DHCP and press [On/Yes]. When prompted,
turn the GC off and then on again.
To set the LAN address at the keyboard
1 Press [Options]. Scroll to Communications and press [Enter].
Advanced User Guide
2
Scroll to Enable DHCP and, if necessary, press [Off/No]. Scroll
to Reboot GC. Press [On/Yes] and [On/Yes].
3
Press [Options]. Scroll to Communications and press [Enter].
4
Scroll to IP. Enter the numbers of the GC IP address,
separated by dots, and press [Enter]. A message tells you to
power cycle the instrument. Do not power cycle yet. Press
[Clear].
5
Scroll to GW. Enter the Gateway number and press [Enter]. A
message tells you to power cycle the instrument. Do not
power cycle yet. Press [Clear].
6
Scroll to SM and press [Mode/Type]. Scroll to the appropriate
subnet mask from the list given and press [Enter]. A message
tells you to power cycle the instrument. Do not power cycle
yet. Press [Clear].
7
Scroll to Reboot GC. Press [On/Yes] and [On/Yes] to power
cycle the instrument and apply the LAN setpoints.
65
3
Options
Keyboard and Display
Press [Options] and scroll to Keyboard and Display. Press
[Mode/Type].
The following parameters are turned on and off by pressing the
[On/Yes] or [Off/No] keys.
Keyboard lock These keys and functions are operational when
the keyboard lock is On:
[Start], [Stop], and [Prep Run]
[Load][Method] and [Load][Seq]
[Seq]—to edit existing sequences
[Seq Control]—to start or stop sequences.
Hard configuration lock On prevents keyboard configuration
changes; Off removes lock.
Key click
Click sound when keys are pressed.
Warning beep
Allows you to hear warning beeps.
Warning beep mode There are 9 different warning sounds that
may be selected. This allows you to give multiple GCs individual
“voices”. We suggest you experiment.
Method modified beep Turn on for high pitched beep when
method setpoint is modified.
Press [Mode/Type] to change the pressure units and radix type.
Pressure units
psi—pounds per square inch, lb/in2
bar—absolute cgs unit of pressure, dyne/cm2
kPa—mks unit of pressure, 103 N/m2
Language
Radix type
1,00
Select English or Chinese.
Determines the numeric separator type—1.00 or
Display saver If On, dims the display after a period of
inactivity. If Off, disabled.
66
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
4
Chromatographic Checkout
About Chromatographic Checkout 68
To Prepare for Chromatographic Checkout 69
To Check FID Performance 71
To Check TCD Performance 76
To Check NPD Performance 81
To Check uECD Performance 86
To Check FPD Performance (Sample 5188-5953) 91
To Verify FPD Performance (Sample 5188-5245) 98
Agilent Technologies
67
4
Chromatographic Checkout
About Chromatographic Checkout
The tests described in this section provide basic confirmation
that the GC and detector can perform comparably to factory
condition. However, as detectors and the other parts of the GC
age, detector performance can change. The results presented
here represent typical outputs for typical operating conditions
and are not specifications.
The tests assume the following:
• Use of an automatic liquid sampler. If not available, use a
suitable manual syringe instead of the syringe listed.
• Use of a 10- µL syringe in most cases. However, a 5- µL
syringe is an acceptable substitute for the 1- µL injections
described here.
• Use of the septa and other hardware (liners, jets, adapters,
and so forth) described. If you substitute other hardware,
performance can vary.
Selected tests described in this section can be run automatically
using the documentation and utility DVD provided with your
GC.
68
Advanced User Guide
Chromatographic Checkout
4
To Prepare for Chromatographic Checkout
Because of the differences in chromatographic performance
associated with different consumables, Agilent strongly
recommends using the parts listed here for all checkout tests.
Agilent also recommends installing new consumable parts
whenever the quality of the installed ones is not known. For
example, installing a new liner and septum ensures that they
will not contribute any contamination to the results.
1 Check the indicators/dates on any gas supply traps.
Replace/recondition expended traps.
2
Install new consumable parts for the inlet and prepare the
correct injector syringe (and needle, as needed).
Table 8
Recommended parts for checkout by inlet type
Recommended part for checkout
Part number
Split splitless inlet
Syringe, 10-µL
5181-1267
O-ring
5188-5365
Septum
5183-4757
Liner
5183-4711 (FID)
5062-3587 or 5181-3316
(TCD, uECD, FPD, NPD)
Multimode inlet
Syringe, 10-µL
5181-1267
O-ring
5188-6405
Septum
5183-4757
Liner
5188-6568
Packed column inlet
Syringe, 10-µL
5181-1267
O-ring
5080-8898
Septum
5183-4757
Cool on-column inlet
Advanced User Guide
Septum
5183-4758
Septum nut
19245-80521
Syringe, 5-µL on-column
5182-0836
69
4
Chromatographic Checkout
Table 8
Recommended parts for checkout by inlet type (continued)
Recommended part for checkout
Part number
0.32-mm needle for 5-µL syringe
5182-0831
7693A ALS: Needle support insert, COC
G4513-40529
7683B ALS: Needle support assembly for
0.25/0.32 mm injections
G2913-60977
Insert, fused silica, 0.32-mm id
19245-20525
PTV inlet
70
Syringe, 10-µL—for septum head
Syringe, 10-µL, 23/42/HP—for septumless head
5181-1267
5181-8809
Inlet adapter, Graphpak-2M
5182-9761
Silver seal for Graphpak-2M
5182-9763
Glass liner, multibaffle
5183-2037
Teflon ferrule (septumless head)
5182-9748
Microseal replacement (if installed)
5182-3444
Ferrule, Graphpak-3D
5182-9749
Advanced User Guide
4
Chromatographic Checkout
To Check FID Performance
1 Gather the following:
• Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm
(19091J- 413)
• FID performance evaluation (checkout) sample
(5188- 5372)
• Chromatographic- grade isooctane
• 4- mL solvent and waste bottles or equivalent for
autoinjector
• 2- mL sample vials or equivalent for sample
2
Verify the following:
• Capillary column jet installed. If not, select and install a
capillary column jet.
• Capillary column adapter installed (adaptable FID only).
If not, install it.
• Chromatographic- grade gases plumbed and configured:
helium as carrier gas, nitrogen, hydrogen, and air.
• Empty waste vials loaded in sample turret.
• 4- mL solvent vial with diffusion cap filled with isooctane
and inserted in Solvent A injector position.
3
Install the evaluation column. (See the procedure for the SS,
PP, COC, MMI, or PTV in the Maintenance manual.)
• Bake out the evaluation column for at least 30 min at
180 °C. (See the procedure for the SS, PP, COC, MMI, or
PTV in the Maintenance manual.)
• Be sure to configure the column.
4
Check the FID baseline output. The output should be
between 5 pA and 20 pA and relatively stable. (If using a gas
generator or ultra pure gas, the signal may stabilize below
5 pA.) If the output is outside this range or unstable, resolve
this problem before continuing.
5
If the output is too low:
• Check that the electrometer is on.
• Check that the flame is lit (“To light the FID flame” on
page 300).
6
Advanced User Guide
Create or load a method with the parameter values listed in
Table 9.
71
4
Chromatographic Checkout
Table 9
FID Checkout Conditions
Column and sample
Type
HP-5, 30 m × 0.32 mm × 0.25 µm
(19091J-413)
Sample
FID checkout 5188-5372
Column flow
6.5 mL/min
Column mode
Constant flow
Split/splitless inlet
Temperature
250 °C
Mode
Splitless
Purge flow
40 mL/min
Purge time
0.5 min
Septum purge
3 mL/min
Gas saver
Off
Multimode inlet
Mode
Splitless
Inlet temperature
75 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
250 °C
Final time 1
5.0 min
Purge time
1.0 min
Purge flow
40 mL/min
Septum purge
3 mL/min
Packed column inlet
Temperature
250 °C
Septum purge
3 mL/min
Cool on-column inlet
Temperature
Oven Track
Septum purge
15 mL/min
PTV inlet
Mode
72
Splitless
Advanced User Guide
Chromatographic Checkout
Table 9
4
FID Checkout Conditions (continued)
Inlet temperature
75 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Rate 2
100 °C/min
Final temp 2
250 °C
Final time 2
0 min
Purge time
0.5 min
Purge flow
40 mL/min
Septum purge
3 mL/min
Detector
Temperature
300 °C
H2 flow
30 mL/min
Air flow
400 mL/min
Makeup flow (N2)
25 mL/min
Lit offset
Typically 2 pA
Oven
Initial temp
75 °C
Initial time
0.5 min
Rate 1
20 °C/min
Final temp
190 °C
Final time
0 min
ALS settings (if installed)
Advanced User Guide
Sample washes
2
Sample pumps
6
Sample wash volume
8
Injection volume
1 µL
Syringe size
10 µL
Solvent A pre washes
2
Solvent A post washes
2
73
4
Chromatographic Checkout
Table 9
FID Checkout Conditions (continued)
Solvent A wash volume
8
Solvent B pre washes
0
Solvent B post washes
0
Solvent B wash volume
0
Injection mode (7693A)
Normal
Airgap Volume (7693A)
0.20
Viscosity delay
0
Inject Dispense Speed (7693A)
6000
Plunger speed (7683)
Fast, for all inlets except COC.
PreInjection dwell
0
PostInjection dwell
0
Manual injection
Injection volume
1 µL
Data system
Data rate
7
5 Hz
If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
If not using a data system, create a one sample sequence
using the GC keypad.
8
Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
9
74
The following chromatogram shows typical results for a new
detector with new consumable parts installed and nitrogen
makeup gas.
Advanced User Guide
Chromatographic Checkout
FID1 A, (C:\FID.D)
C15
pA
400
4
C16
350
300
250
200
150
100
C13
50
C14
0
0
1
Advanced User Guide
2
3
4
5
min
75
4
Chromatographic Checkout
To Check TCD Performance
1 Gather the following:
• Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm
(19091J- 413)
• FID/TCD performance evaluation (checkout) sample
(18710- 60170)
• 4- mL solvent and waste bottles or equivalent for
autoinjector
• Chromatographic- grade hexane
• 2- mL sample vials or equivalent for sample
• Chromatographic- grade helium as carrier, makeup, and
reference gas
2
Verify the following:
• Chromatographic- grade gases plumbed and configured:
helium as carrier gas and reference gas.
• Empty waste vials loaded in sample turret.
• 4- mL solvent vial with diffusion cap filled with hexane
and inserted in Solvent A injector position.
3
Install the evaluation column. (See the procedure for the SS,
PP, COC, MMI, or PTV in the Maintenance manual.)
• Bake out the evaluation column for at least 30 min at
180 °C. (See the procedure for the SS, PP, COC, MMI, or
PTV in the Maintenance manual.)
• Configure the column
4
Create or load a method with the parameter values listed in
Table 10.
Table 10
TCD Checkout Conditions
Column and sample
Type
HP-5, 30 m × 0.32 mm × 0.25 µm
(19091J-413)
Sample
FID/TCD checkout 18710-60170
Column flow
6.5 mL/min
Column mode
Constant flow
Split/splitless inlet
Temperature
76
250 °C
Advanced User Guide
Chromatographic Checkout
Table 10
4
TCD Checkout Conditions (continued)
Mode
Splitless
Purge flow
60 mL/min
Purge time
0.75 min
Septum purge
3 mL/min
Multimode inlet
Mode
Splitless
Inlet temperature
40 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Purge time
1.0 min
Purge flow
40 mL/min
Septum purge
3 mL/min
Packed column inlet
Temperature
250 °C
Septum purge
3 mL/min
Cool on-column inlet
Temperature
Oven track
Septum purge
15 mL/min
PTV inlet
Advanced User Guide
Mode
Splitless
Inlet temperature
40 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Rate 2
100 °C/min
Final temp 2
250 °C
Final time 2
0 min
Purge time
0.5 min
Purge flow
40 mL/min
77
4
Chromatographic Checkout
Table 10
TCD Checkout Conditions (continued)
Septum purge
3 mL/min
Detector
Temperature
300 °C
Reference flow (He)
20 mL/min
Makeup flow (He)
2 mL/min
Baseline output
< 30 display counts on Agilent
ChemStation (< 750 µV)
Oven
Initial temp
40 °C
Initial time
0 min
Rate 1
20 °C/min
Final temp
90 °C
Final time
0 min
Rate 2
15 °C/min
Final temp
170 °C
Final time
0 min
ALS settings (if installed)
78
Sample washes
2
Sample pumps
6
Sample wash volume
8
Injection volume
1 µL
Syringe size
10 µL
Solvent A pre washes
2
Solvent A post washes
2
Solvent A wash volume
8
Solvent B pre washes
0
Solvent B post washes
0
Solvent B wash volume
0
Injection mode (7693A)
Normal
Airgap Volume (7693A)
0.20
Viscosity delay
0
Inject Dispense Speed (7693A)
6000
Advanced User Guide
4
Chromatographic Checkout
Table 10
TCD Checkout Conditions (continued)
Plunger speed (7683)
Fast, for all inlets except COC.
PreInjection dwell
0
PostInjection dwell
0
Manual injection
Injection volume
1 µL
Data system
Data rate
5
5 Hz
Display the signal output. A stable output at any value
between 12.5 and 750 µV (inclusive) is acceptable.
• If the baseline output is < 0.5 display units (< 12.5 µV),
verify that the detector filament is on. If the offset is still
< 0.5 display units (< 12.5 µV), your detector requires
service.
• If baseline output is > 30 display units (> 750 µV), there
may be chemical contamination contributing to the signal.
Bakeout the TCD. If repeated cleanings do not give an
acceptable signal, check gas purity. Use higher purity
gases and/or install traps.
6
If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
7
Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
8
Advanced User Guide
The following chromatogram shows typical results for a new
detector with new consumable parts installed.
79
4
Chromatographic Checkout
25 uV
70
C14
C15
C16
60
50
40
30
20
2
4
6
8
Time (min.)
80
Advanced User Guide
Chromatographic Checkout
4
To Check NPD Performance
1 Gather the following:
• Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm
(19091J- 413)
• NPD performance evaluation (checkout) sample
(18789- 60060)
• 4- mL solvent and waste bottles or equivalent for
autoinjector.
• Chromatographic- grade isooctane
• 2- mL sample vials or equivalent for sample.
2
Verify the following:
• Capillary column jet installed. If not, select and install a
capillary column jet.
• Capillary column adapter installed. If not, install it.
• Chromatographic- grade gases plumbed and configured:
helium as carrier gas, nitrogen, hydrogen, and air.
• Empty waste vials loaded in sample turret.
• 4- mL vial with diffusion cap filled with isooctane and
inserted in Solvent A injector position.
3
If present, remove any protective caps from the inlet
manifold vents.
4
Install the evaluation column. (See the procedure for the SS,
PP, COC, MMI, or PTV in the Maintenance manual.)
• Bake out the evaluation column for at least 30 min at
180 °C. (See the procedure for the SS, PP, COC, MMI, or
PTV in the Maintenance manual.)
• Be sure to configure the column
5
Create or load a method with the parameter values listed in
Table 11.
Table 11
NPD Checkout Conditions
Column and sample
Advanced User Guide
Type
HP-5, 30 m × 0.32 mm × 0.25 µm
(19091J-413)
Sample
NPD checkout 18789-60060
Column mode
Constant flow
81
4
Chromatographic Checkout
Table 11
NPD Checkout Conditions (continued)
Column flow
6.5 mL/min (helium)
Split/splitless inlet
Temperature
200 °C
Mode
Splitless
Purge flow
60 mL/min
Purge time
0.75 min
Septum purge
3 mL/min
Multimode inlet
Mode
Splitless
Inlet temperature
60 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Purge time
1.0 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Packed column inlet
Temperature
200 °C
Septum purge
3 mL/min
Cool on-column inlet
Temperature
Oven track
Septum purge
15 mL/min
PTV inlet
82
Mode
Splitless
Inlet temperature
60 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Rate 2
100 °C/min
Final temp 2
250 °C
Advanced User Guide
Chromatographic Checkout
Table 11
4
NPD Checkout Conditions (continued)
Final time 2
0 min
Purge time
0.75 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Detector
Temperature
300 °C
H2 flow
3 mL/min
Air flow
60 mL/min
Makeup flow (N2)
Makeup + column = 10 mL/min
Output
30 display units (30 pA)
Oven
Initial temp
60 °C
Initial time
0 min
Rate 1
20 °C/min
Final temp
200 °C
Final time
3 min
ALS settings (if installed)
Advanced User Guide
Sample washes
2
Sample pumps
6
Sample wash volume
8
Injection volume
1 µL
Syringe size
10 µL
Solvent A pre washes
2
Solvent A post washes
2
Solvent A wash volume
8
Solvent B pre washes
0
Solvent B post washes
0
Solvent B wash volume
0
Injection mode (7693A)
Normal
Airgap Volume (7693A)
0.20
Viscosity delay
0
83
4
Chromatographic Checkout
Table 11
NPD Checkout Conditions (continued)
Inject Dispense Speed (7693A)
6000
Plunger speed (7683)
Fast, for all inlets except COC.
PreInjection dwell
0
PostInjection dwell
0
Manual injection
Injection volume
1 µL
Data system
Data rate
5 Hz
6
If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
7
Start the run.
If performing an injection using an autosampler, start the
run using the data system, or creating a one sample sequence
and pressing [Start] on the GC.
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
8
84
The following chromatogram shows typical results for a new
detector with new consumable parts installed.
Advanced User Guide
Chromatographic Checkout
NPD1 B, (C:\NPD.D)
4
Malathion
pA
70
60
Azobenzene
50
40
30
20
Octadecane
10
1
Advanced User Guide
2
3
4
5
6
7
8
9
m
85
4
Chromatographic Checkout
To Check uECD Performance
1 Gather the following:
• Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm
(19091J- 413)
• uECD performance evaluation (checkout) sample
(18713–60040, Japan: 5183- 0379)
• 4- mL solvent and waste bottles or equivalent for
autoinjector.
• Chromatographic- grade isooctane
• 2- mL sample vials or equivalent for sample.
2
Verify the following:
• Clean fused silica indented mixing liner installed. If not,
install it.
• Chromatographic- grade gases plumbed and configured:
helium for carrier gas, nitrogen for makeup.
• Empty waste vials loaded in sample turret.
• 4- mL vial with diffusion cap filled with hexane and
inserted in Solvent A injector position.
3
Install the evaluation column. (See the procedure for the SS,
PP, COC, MMI, or PTV in the Maintenance manual.)
• Bake out the evaluation column for at least 30 minutes at
180 °C. (See the procedure for the SS, PP, COC, MMI, or
PTV in the Maintenance manual.)
• Be sure to configure the column.
4
Display the signal output to determine baseline output. A
stable baseline output at any value between 0.5 and 1000 Hz
(ChemStation display units) (inclusive) is acceptable.
• If the baseline output is < 0.5 Hz, verify that the
electrometer is on. If the offset is still < 0.5 Hz, your
detector requires service.
• If the baseline output is > 1000 Hz, there may be chemical
contamination contributing to the signal. Bakeout the
uECD. If repeated cleanings do not give an acceptable
signal, check gas purity. Use higher purity gases and/or
install traps.
5
86
Create or load a method with the parameter values listed in
Table 12.
Advanced User Guide
Chromatographic Checkout
Table 12
4
uECD Checkout Conditions
Column and sample
Type
HP-5, 30 m × 0.32 mm × 0.25 µm
(19091J-413
Sample
µECD checkout (18713-60040 or Japan:
5183-0379)
Column mode
Constant flow
Column flow
6.5 mL/min (helium)
Split/splitless inlet
Temperature
200 °C
Mode
Splitless
Purge flow
60 mL/min
Purge time
0.75 min
Septum purge
3 mL/min
Multimode inlet
Mode
Splitless
Inlet temperature
80 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
250 °C
Final time 1
5 min
Purge time
1.0 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Packed column inlet
Temperature
200 °C
Septum purge
3 mL/min
Cool on-column inlet
Temperature
Oven track
Septum purge
15 mL/min
PTV inlet
Mode
Advanced User Guide
Splitless
87
4
Chromatographic Checkout
Table 12
uECD Checkout Conditions (continued)
Inlet temperature
80 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Rate 2
100 °C/min
Final temp 2
250 °C
Final time 2
0 min
Purge time
0.75 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Detector
Temperature
300 °C
Makeup flow (N2)
30 mL/min (constant + makeup)
Baseline output
Should be < 1000 display counts in
Agilent ChemStation (< 1000 Hz)
Oven
Initial temp
80 °C
Initial time
0 min
Rate 1
15 °C/min
Final temp
180 °C
Final time
10 min
ALS settings (if installed)
88
Sample washes
2
Sample pumps
6
Sample wash volume
8
Injection volume
1 µL
Syringe size
10 µL
Solvent A pre washes
2
Solvent A post washes
2
Solvent A wash volume
8
Solvent B pre washes
0
Advanced User Guide
Chromatographic Checkout
Table 12
4
uECD Checkout Conditions (continued)
Solvent B post washes
0
Solvent B wash volume
0
Injection mode (7693A)
Normal
Airgap Volume (7693A)
0.20
Viscosity delay
0
Inject Dispense Speed (7693A)
6000
Plunger speed (7683)
Fast, for all inlets except COC.
PreInjection dwell
0
PostInjection dwell
0
Manual injection
Injection volume
1 µL
Data system
Data rate
5 Hz
6
If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
7
Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
8
Advanced User Guide
The following chromatogram shows typical results for a new
detector with new consumable parts installed.
89
4
Chromatographic Checkout
ECD1 B, (C:\ECD.D)
Hz
Lindane
(18713-60040
5183-0379)
12000
10000
8000
Aldrin
(18713-60040)
6000
4000
2000
0
2
90
4
6
8
10
12 min
Advanced User Guide
Chromatographic Checkout
4
To Check FPD Performance (Sample 5188-5953)
To check FPD performance, first check the phosphorus
performance, then the sulfur performance.
Preparation
1 Gather the following:
• Evaluation column, HP- 5 30 m × 0.32 mm × 0.25 µm
(19091J- 413)
• FPD performance evaluation (checkout) sample
(5188- 5953)
• Phosphorus filter
• Sulfur filter and filter spacer
• 4- mL solvent and waste bottles or equivalent for
autoinjector.
• 2- mL sample vials or equivalent for sample.
• Chromatographic- grade isooctane for syringe wash
solvent.
2
Verify the following:
• Capillary column adapter installed. If not, install it.
• Chromatographic- grade gases plumbed and configured:
helium as carrier gas, nitrogen, hydrogen, and air.
• Empty waste vials loaded in sample turret.
• 4- mL vial with diffusion cap filled with isooctane and
inserted in Solvent A injector position.
3
Verify that the Lit Offset is set appropriately. Typically, it
should be about 2.0 pA for the checkout method.
4
Install the evaluation column. (See the procedure for the SS,
PP, COC, MMI, or PTV in the Maintenance manual.)
• Set the oven, inlet, and detector to 250 °C and bake out for
at least 15 minutes. (See the procedure for the SS, PP,
COC, MMI, or PTV in the Maintenance manual.)
• Be sure to configure the column.
Phosphorus performance
Advanced User Guide
5
If it is not already installed, install the phosphorus filter.
6
Create or load a method with the parameter values listed in
Table 13.
91
4
Chromatographic Checkout
Table 13
FPD Checkout Conditions (P)
Column and sample
Type
HP-5, 30 m × 0.32 mm × 0.25 µm
(19091J-413)
Sample
FPD checkout (5188-5953)
Column mode
Constant pressure
Column pressure
25 psi
Split/splitless inlet
Temperature
200 °C Split/splitless
Mode
Splitless
Purge flow
60 mL/min
Purge time
0.75 min
Septum purge
3 mL/min
Multimode inlet
Mode
Splitless
Inlet temperature
75 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
250 °C
Final time 1
5.0 min
Purge time
1.0 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Packed column inlet
Temperature
200 °C
Septum purge
3 mL/min
Cool on-column inlet
Temperature
Oven track
Septum purge
15 mL/min
PTV inlet
92
Mode
Splitless
Inlet temperature
75 °C
Advanced User Guide
Chromatographic Checkout
Table 13
4
FPD Checkout Conditions (continued)(P)
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Rate 2
100 °C/min
Final temp 2
250 °C
Final time 2
0 min
Purge time
0.75 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Detector
Temperature
200 °C (On)
Hydrogen flow
75 mL/min (On)
Air (Oxidizer) flow
100 mL/min (On)
Mode
Constant makeup flow OFF
Makeup flow
60 mL/min (On)
Makeup gas type
Nitrogen
Flame
On
Lit offset
Typically 2 pA
High voltage
On
Oven
Initial temp
70 °C
Initial time
0 min
Rate 1
25 °C/min
Final temp 1
150 °C
Final time 1
0 min
Rate 2
5 °C/min
Final temp 2
190 °C
Final time 2
4 min
ALS settings (if installed)
Sample washes
Advanced User Guide
2
93
4
Chromatographic Checkout
Table 13
FPD Checkout Conditions (continued)(P)
Sample pumps
6
Sample wash volume
8
Injection volume
1 µL
Syringe size
10 µL
Solvent A pre washes
2
Solvent A post washes
2
Solvent A wash volume
8
Solvent B pre washes
0
Solvent B post washes
0
Solvent B wash volume
0
Injection mode (7693A)
Normal
Airgap Volume (7693A)
0.20
Viscosity delay
0
Inject Dispense Speed (7693A)
6000
Plunger speed (7683)
Fast, for all inlets except COC.
PreInjection dwell
0
PostInjection dwell
0
Manual injection
Injection volume
1 µL
Data system
Data rate
5 Hz
7
Ignite the FPD flame, if not lit.
8
Display the signal output and monitor. This output typically
runs between 40 and 55 but can be as high as 70. Wait for the
output to level off. This takes approximately 1 hour.
If the baseline output is too high:
• Check column installation. If installed high, the stationery
phase burns out and increases measured output.
• Check for leaks.
• Bake out the detector and column at 250 °C.
• Wrong flows set for installed filter.
94
Advanced User Guide
Chromatographic Checkout
4
If the baseline output is zero, verify the electrometer is on
and the flame is lit.
9
If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
10 Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
11 The following chromatogram shows typical results for a new
detector with new consumable parts installed.
Methylparathion
Isooctane
Table 14
Advanced User Guide
Evaluating checkout runs
FPD P filter
Typical range after 24
hours
Limits at installation
MDL (pg/sec)
0.06 to 0.08
≤0.10
Peak area
19000 to 32000
≥19000
Signal height
5000 to 11000
—
95
4
Chromatographic Checkout
Table 14
Evaluating checkout runs
FPD P filter
Typical range after 24
hours
Limits at installation
Noise
1.6 to 3.0
≤4
Half-width (min)
0.05 to 0.07
—
Output
34 to 80
≤80
Sulfur performance
12 Install the sulfur filter and filter spacer.
13 Make the following method parameter changes.
Table 15
Sulfur method parameters (S)
Parameter
Value ( mL/min)
H2 flow
50
Air flow
60
14 Ignite the FPD flame if not lit.
15 Display the signal output and monitor. This output typically
runs between 50 and 60 but can be as high as 70. Wait for the
output to level off. This takes approximately 1 hour.
If the baseline output is too high:
• Check column installation. If installed high, the stationery
phase burns out and increases measured output.
• Check for leaks.
• Bake out the detector and column at 250 °C.
• Wrong flows set for installed filter.
If the baseline output is zero, verify the electrometer is on
and the flame is lit.
16 If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
17 Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
96
Advanced User Guide
Chromatographic Checkout
4
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
18 The following chromatogram shows typical results for a new
detector with new consumable parts installed.
Tributyl phosphate
Isooctane
Table 16
Advanced User Guide
Evaluating checkout runs
FPD S filter
Typical range after 24
hours
Limits at installation
MDL (pg/s)
3.8 to 5
≤6
Peak area
8000 to 19000
≥8000
Signal height
2500 to 6000
—
Noise
2 to 4
≤5
Half-width (min)
0.06 to 0.08
—
Output
34 to 65
≤70
97
4
Chromatographic Checkout
To Verify FPD Performance (Sample 5188-5245)
To verify FPD performance, first check the phosphorus
performance, then the sulfur performance.
Preparation
1 Gather the following:
• Evaluation column, DB5 15 m × 0.32 mm × 1.0 µm
(123- 5513)
• FPD performance evaluation (checkout) sample
(5188- 5245)
• Phosphorus filter
• Sulfur filter and filter spacer
• 4- mL solvent and waste bottles or equivalent for
autoinjector.
• 2- mL sample vials or equivalent for sample.
• Chromatographic- grade isooctane for syringe wash
solvent.
2
Verify the following:
• Capillary column adapter installed. If not, install it.
• Chromatographic- grade gases plumbed and configured:
helium as carrier gas, nitrogen, hydrogen, and air.
• Empty waste vials loaded in sample turret.
• 4- mL vial with diffusion cap filled with isooctane and
inserted in Solvent A injector position.
3
Verify the lit offset is set appropriately. Typically, it should
be about 2.0 pA for the checkout method.
4
Install the evaluation column. (See the procedure for the SS,
PP, COC, MMI, or PTV in the Maintenance manual.)
• Set the oven, inlet, and detector to 250 °C and bake out for
at least 15 minutes. (See the procedure for the SS, PP,
COC, MMI, or PTV in the Maintenance manual.)
• Configure the column.
Phosphorus performance
98
5
If it is not already installed, install the phosphorus filter.
6
Create or load a method with the parameter values listed in
Table 17.
Advanced User Guide
Chromatographic Checkout
Table 17
4
FPD Phosphorus Checkout Conditions
Column and sample
Type
DB-5MS, 15 m × 0.32 mm × 1.0 µm
(123-5513)
Sample
FPD checkout (5188-5245)
Column mode
Constant flow
Column flow
7.5 mL/min
Split/splitless inlet
Temperature
250 °C
Mode
Splitless
Total purge flow
69.5 mL/min
Purge flow
60 mL/min
Purge time
0.75 min
Septum purge
3 mL/min
Multimode inlet
Mode
Splitless
Inlet temperature
80 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
250 °C
Final time 1
5.0 min
Purge time
1.0 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Packed column inlet
Temperature
250 °C
Septum purge
3 mL/min
Cool on-column inlet
Temperature
Oven track
Septum purge
15 mL/min
PTV inlet
Mode
Advanced User Guide
Splitless
99
4
Chromatographic Checkout
Table 17
FPD Phosphorus Checkout Conditions (continued)
Inlet temperature
80 °C
Initial time
0.1 min
Rate 1
720 °C/min
Final temp 1
350 °C
Final time 1
2 min
Rate 2
100 °C/min
Final temp 2
250 °C
Final time 2
0 min
Purge time
0.75 min
Purge flow
60 mL/min
Septum purge
3 mL/min
Detector
Temperature
200 °C (On)
Hydrogen flow
75.0 mL/min (On)
Air (oxidizer) flow
100.0 mL/min (On)
Mode
Constant makeup flow Off
Makeup flow
60.0 mL/min (On)
Makeup gas type
Nitrogen
Flame
On
Lit offset
Typically 2 pA
High voltage
On
Oven
Initial temp
70 °C
Initial time
0 min
Rate 1
10 °C/min
Final temp
105 °C
Final time
0 min
Rate 2
20 °C/min
Final temp 2
190 °C
Final time 2
7.25 min for sulfur
12.25 min for phosphorus
ALS settings (if installed)
100
Advanced User Guide
Chromatographic Checkout
Table 17
4
FPD Phosphorus Checkout Conditions (continued)
Sample washes
2
Sample pumps
6
Sample wash volume
8
Injection volume
1 µL
Syringe size
10 µL
Solvent A pre washes
2
Solvent A post washes
2
Solvent A wash volume
8
Solvent B pre washes
0
Solvent B post washes
0
Solvent B wash volume
0
Injection mode (7693A)
Normal
Airgap Volume (7693A)
0.20
Viscosity delay
0
Inject Dispense Speed (7693A)
6000
Plunger speed (7683)
Fast, for all inlets except COC.
PreInjection dwell
0
PostInjection dwell
0
Manual injection
Injection volume
1 µL
Data System
Data rate
5 Hz
7
Ignite the FPD flame, if not lit.
8
Display the signal output and monitor. This output typically
runs between 40 and 55 but can be as high as 70. Wait for the
output to level off. This takes approximately 1 hour.
If the baseline output is too high:
• Check column installation. If installed high, the stationery
phase burns out and increases measured output.
• Check for leaks.
• Bake out the detector and column at 250 °C.
• Wrong flows set for installed filter
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101
4
Chromatographic Checkout
If the baseline output is zero, verify the electrometer is on
and the flame is lit.
9
If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure that
the data system will output a chromatogram.
10 Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
11 The following chromatogram shows typical results for a new
detector with new consumable parts installed.
Tributylphosphate
Isooctane
t-Butyldisulfide
Table 18
102
Evaluating checkout runs
FPD P filter
Typical range after 24
hours
Limits at installation
MDL (pg/sec)
0.06 to 0.08
≤0.10
Peak area
19000 to 32000
≥19000
Signal height
5000 to 11000
—
Advanced User Guide
4
Chromatographic Checkout
Table 18
Evaluating checkout runs
FPD P filter
Typical range after 24
hours
Limits at installation
Noise
1.6 to 3.0
≤4
Half-width (min)
0.05 to 0.07
—
Output
34 to 80
≤80
Sulfur performance
12 Install the sulfur filter.
13 Make the following method parameter changes.
Table 19
Sulfur method parameters
Parameter
Value ( mL/min)
H2 flow
50
Air flow
60
14 Ignite the FPD flame, if not lit.
15 Display the signal output and monitor. This output typically
runs between 50 and 60 but can be as high as 70. Wait for the
output to level off. This takes approximately 2 hours.
If the baseline output is too high:
• Check column installation. If installed high, the stationery
phase burns out and increases measured output.
• Check for leaks.
• Bake out the detector and column at 250 °C.
• Wrong flows set for installed filter
If the baseline output is zero, verify the electrometer is on
and the flame is lit.
16 If using a data system, prepare the data system to perform
one run using the loaded checkout method. Make sure the
data system will output a chromatogram.
17 Start the run.
If performing an injection using an autosampler, start the
run using the data system or press [Start] on the GC.
Advanced User Guide
103
4
Chromatographic Checkout
If performing a manual injection (with or without a data
system):
a Press [Prep Run] to prepare the inlet for splitless injection.
b When the GC becomes ready, inject 1 µL of the checkout
sample and press [Start] on the GC.
18 The following chromatogram shows typical results for a new
detector with new consumable parts installed.
t-Butyldisulfide
1-Dodecanethiol
Isooctane
Table 20
104
Evaluating checkout runs
FPD S filter
Typical range after 24
hours
Limits at installation
MDL (pg/s)
3.8 to 5
≤6
Peak area
8000 to 19000
≥8000
Signal height
2500 to 6000
—
Noise
2 to 4
≤5
Half-width (min)
0.06 to 0.08
—
Output
34 to 65
≤70
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
5
Methods and Sequences
Creating Methods 106
To program a method 107
To program the ALS 107
To program the ALS sampler tray 107
To program the 7683B ALS bar code reader 108
To save a method 109
To load a stored method 109
Method mismatch 109
Creating Sequences 111
About the priority sequence 111
To program a sequence 111
To program a priority sequence 112
To program an ALS subsequence 113
To program a valve subsequence 113
To program post sequence events 113
To save a sequence 114
To load a stored sequence 114
To determine sequence status 114
To start a sequence 114
To pause and resume a sequence 115
To stop a sequence 115
To abort a sequence 115
Agilent Technologies
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5
Methods and Sequences
Creating Methods
A method is the group of setpoints needed to run a single
sample on the GC, such as oven temperature programs,
pressure programs, inlet temperatures, sampler parameters,
etc. A method is created by saving a group of setpoints as a
numbered method using the [Store] key. At least 10 methods can
be stored.
Components for which setpoint parameters can be stored are
shown in Table 21.
Table 21
Setpoint parameter components
Component
Component
Oven
Aux temp
Valve 1–8
Aux EPC
Front and back inlet
Aux column
Columns 1 to 6
Aux detector 1 and 2
Front and back detector
Post run
Analog 1 and 2
Run table
Front and back injector (see Table 22)
Sample tray
Table 22 lists the setpoint parameters for the 7683B ALS.
Table 22
106
7683B ALS setpoint parameters
Parameter
Parameter
Injection volume
Sample Draw Speed
Viscosity delay
Sample Disp Speed
Inject Dispense Speed
Solvent Draw Speed
Sample pumps
Solvent Disp Speed
Sample washes
Slow plunger
Solvent A post washes
Pre dwell time
Solvent A pre washes
Post dwell time
Solvent B post washes
Sample offset
Solvent B pre washes
Injection Reps
Solvent B wash volume
Injection Delay
Advanced User Guide
5
Methods and Sequences
The GC also saves ALS setpoints. See the 7693A Installation,
Operation, and Maintenance manual for details on its setpoints.
Setpoint parameters are saved when the GC is turned off and
loaded when you turn the instrument back on. However, if the
hardware was changed while the instrument was turned off, it
may not be possible to restore all setpoints in the method.
To program a method
1 Individually select each component for which setpoint
parameters are appropriate for your method. (See Table 21.)
2
Examine the current setpoints and modify as desired.
Repeat for each component as appropriate.
3
Examine the current setpoints for the ALS, if appropriate,
and modify as desired. (See “To program the ALS” on
page 107.)
4
Save the setpoints as a stored method. (See “To save a
method” on page 109.)
To program the ALS
1 Press [Front Injector] or [Back Injector].
2
Scroll to the desired setpoint. (See Table 22.)
3
Enter a setpoint value.
4
Examine the current setpoints for the sampler tray, if
appropriate, and modify as desired. (See “To program the
ALS sampler tray” on page 107.)
5
Examine the current setpoints for the bar code reader, if
appropriate, and modify as desired. (See “To program the
7683B ALS bar code reader” on page 108.)
6
Save the setpoints as a stored method. (See “To save a
method” on page 109.)
To program the ALS sampler tray
For the 7693A sampler tray, see the 7693A Installation,
Operation, and Maintenance manual.
For the 7683B sampler tray:
1 Press [Sample tray].
2
Advanced User Guide
Press [On/Yes] to enable the barcode reader (if present) or
[Off/No] to disable it.
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5
Methods and Sequences
Configuration issues
1 To edit the sample tray configuration setpoints, press
[Config][Sample Tray].
Normally, no tray configuration is required. If using a
bar code reader and the tray gripper arm has difficulties
retrieving a vial from the bar code reader, adjust the gripper
offset (step 2). If the sample vial contacts the side of the
turret hole when the tray delivers or retrieves the sample
vial, then adjust the injector offset (step 3).
2
Scroll to Grip offset and press [Mode/Type]. Select from:
• Up to raise the gripper arm pickup height
• Default
• Down to lower the gripper arm pickup height
and press [Enter].
3
Scroll to Front Injector Offset or Back Injector Offset and press
[Mode/Type]. Select from:
• Clockwise to have the gripper arm meet the turret at a
further clockwise position (relative to turret rotation)
• Default
• CounterClockwise to have the gripper arm meet the turret
at a further counterclockwise position (relative to turret
rotation)
and press [Enter].
To program the 7683B ALS bar code reader
For the 7693A sampler bar code reader, see the 7693A
Installation, Operation, and Maintenance manual.
1 Press [Sample tray].
2
Scroll to Enable bar code reader and press [On/Yes] to enable or
[Off/No] to disable the bar code reader.
Configuration issues
1 To edit the bar code configuration setpoints, press
[Config][Sample Tray].
108
2
Select Bar Code Reader.
3
Press [On/Yes] or [Off/No] to control the following bar code
setpoints:
Advanced User Guide
5
Methods and Sequences
• Enable 3 of 9—encodes both letters and numbers, plus a few
punctuation marks, and message length can be varied to
suit both the amount of data to be encoded and the space
available
• Enable 2 of 5—restricted to numbers but does allow variable
message length
• Enable UPC code—restricted to numbers- only with fixed
message length
• Enable checksum—verifies that the checksum in the
message matches the checksum calculated from the
message characters, but does not include the checksum
character in the returned message
4
Enter 3 as the BCR Position when the reader is installed in the
front of the tray. Positions 1–19 are available.
To save a method
1 Press [Method] and scroll to the desired method number.
2
Press [Store] and [On/Yes] to store the new method using the
chosen number. Alternatively, press [Off/No] to return to the
stored methods list without saving the method.
A message is displayed if a method with the number you
selected already exists.
• Press [On/Yes] to replace the existing method or [Off/No]
to return to the stored methods list without saving the
method.
To load a stored method
Press [Load][Method]. Supply the method number and press
[Enter]. The specified method will replace the current active
method.
Method mismatch
This section applies only to a standalone (not connected to a
data system) GC. When a data system, such as a ChemStation or
EZChrom Elite, controls the GC, methods are stored in the data
system and can be edited there. See your data system
documentation for more information.
Advanced User Guide
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5
Methods and Sequences
Suppose your standalone GC is equipped with a single FID. You
have created and saved methods that use this detector. Now you
remove the FID and install a TCD in its place. When you try to
load one of your stored methods, you observe an error message
saying that the method and the hardware do not match.
The problem is that the actual hardware is no longer the same
as the hardware configuration saved in the method. The method
cannot run because it does not know how to operate the
recently- added TCD.
On inspecting the method, you find that the detector- related
parameters have all been reset to the default values.
Correcting a method mismatch on a standalone GC
This problem can be avoided if you follow this procedure for any
hardware change, even including the simple replacement of a
defective detector board.
1 Before changing any hardware, press [Config][hardware
module], where [hardware module] is the device you intend to
replace.
110
2
Press [Mode/Type]. Select Remove module and press [Enter].
The module is now Unconfigured.
3
Turn the GC off.
4
Make the hardware change that you intended (in this
example, remove the FID and its flow module and replace
them with the TCD and its module).
5
Turn the GC on. Press [Config][hardware module].
6
Press [Mode/Type]. Select Install module and press [Enter]. The
GC will install the new hardware module, which corrects the
active method (but not the stored one!).
7
Save the corrected method using the same number (which
overwrites the stored method) or a new number (which
saves both versions of the method).
Advanced User Guide
5
Methods and Sequences
Creating Sequences
A sequence specifies the samples to be run and the stored
method to be used for each. The sequence is divided into a
priority sequence (ALS only), subsequences (each of which uses
a single method), and post- sequence events
• Priority sequence—allows you to interrupt a running ALS or
valve sequence to analyze urgent samples. (See “About the
priority sequence” on page 111.)
• Subsequences—contain the stored method number and
information that defines a set of samples and calibrators to
be analyzed using a particular method. Sampler and/or valve
subsequences can be used in the same sequence.
• Post sequence—names a method to be loaded and run after
the last run in the last subsequence. Specifies whether the
sequence is to be repeated indefinitely or halted after the
last subsequence.
Samples in each subsequence are specified as either ALS tray
locations or sampling valve positions (gas or liquid sampling
valves, often with a stream selection valve).
Five sequences with up to five subsequences each can be stored.
About the priority sequence
The priority sequence consists of a single sampler or valve
subsequence and a special Use priority parameter, which can be
activated at any time, even when a sequence is running. This
feature allows you to interrupt a running sequence without
having to edit it.
If Use priority is On, then:
1 The GC and ALS complete the current run, then the sequence
pauses.
2
The GC runs the priority sequence.
3
The GC resets the Use priority parameter to Off.
4
The main sequence resumes where it paused.
To program a sequence
1 Press [Seq]. (Press again, if necessary, to display
subsequence information.)
2
Advanced User Guide
Create a priority sequence, if desired. (See “To program a
priority sequence” on page 112.) If you might want to use a
111
5
Methods and Sequences
priority sequence, you must program it now. (Once the
sequence starts, you cannot edit it without stopping it.)
3
Scroll to the Method # line of Subseq 1 and enter a method
number. Use 0 for the currently active method, 1 to 9 for the
stored methods, or [Off/No] to end the sequence.
4
Press [Mode/Type] to select a valve or injector type. (See “To
program a valve subsequence” on page 113 or “To program
an ALS subsequence” on page 113.)
5
Create the next subsequence or scroll to Post Sequence. (See
“To program post sequence events” on page 113.)
6
Save the completed sequence. (See “To save a sequence” on
page 114.)
To program a priority sequence
1 Press [Seq]. (Press again, if necessary, to display
subsequence information.)
2
Scroll to Priority Method # and enter a method number. Use 0
for the currently active method, 1 to 9 for the stored
methods, or [Off/No] to end the sequence. Press [Enter].
The active method, 0, will change during the sequence if the
subsequences use stored methods. Therefore, method 0
should be chosen for the priority sequence only if all
subsequences use method 0.
3
Press [Mode/Type] and select the injector type.
4
Program the ALS subsequence. (See “To program an ALS
subsequence” on page 113.)
5
Store the completed sequence. (See “To save a sequence” on
page 114.)
Once a priority subsequence exists in a sequence, you can
activate it when the urgent samples are ready to be processed
by:
1 Press [Seq]. (Press again, if necessary, to display
subsequence information.)
2
Scroll to Use Priority and press [On/Yes].
When the priority samples are completed, the normal sequence
resumes.
112
Advanced User Guide
5
Methods and Sequences
To program an ALS subsequence
1 See step 1 through step 3 of “To program a sequence” on
page 111.
2
Press [Mode/Type] and select the injector type.
3
Enter injector sequence parameters (if using both injectors,
there will be two sets of parameters):
• Number of Injections/vial—the number of repeat runs from
each vial. Enter 0 if no samples are to be injected.
• Samples—the range (first–last) of sample vials to be
analyzed.
4
Proceed with step 5 of “To program a sequence” on page 111.
To program a valve subsequence
1 See step 1 through step 3 of “To program a sequence” on
page 111.
2
Press [Mode/Type] and select Valve.
3
Enter the valve sequence parameters (the first three appear
only if a multiposition valve is configured):
• #inj/position—number of injections at each position (0–99)
• Position rng—first–last valve positions to sample (1–32)
• Times thru range—number of times to repeat the range
(1–99)
• # injections—number of injections for each sample
4
Proceed with step 5 of “To program a sequence” on page 111.
To program post sequence events
1 See step 1 through step 4 of “To program a sequence” on
page 111.
Advanced User Guide
2
Scroll to the Method # line of Post Sequence and enter a
method number. Use 1 to 9 for the stored methods, or 0 if
there is no method to be loaded.
3
Press [On/Yes] at Repeat sequence to keep repeating the sequence
(useful for valve sequences). Otherwise, press [Off/No] to halt the
sequence when all subsequences are finished.
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5
Methods and Sequences
To save a sequence
1 Press [Store][Seq].
2
Enter an identifying number for the sequence.
3
Press [On/Yes] to store the sequence. Alternatively, press
[Off/No] to cancel.
A message is displayed if a sequence with the number you
selected already exists.
• Press [On/Yes] to replace the existing sequence or [Off/No]
to cancel.
Sequences can also be stored from within the stored sequence
list ([Seq]) by scrolling to the appropriate sequence number and
pressing the [Store] key.
To load a stored sequence
Press [Load][Seq]. Supply the sequence number and press
[Enter]. The specified sequence will replace the current active
sequence.
To determine sequence status
Press [Seq Control] to display the current status of the active
sequence. There are six possible sequence status modes:
• Start/running
• Ready wait
• Paused/resume
• Stopped
• Aborted
• No sequence
To start a sequence
Press [Seq Control], scroll to Start sequence and press [Enter].
The sequence status will change to Running. The sequence
continues to run until all subsequences are executed, or until
one of the events described under “To abort a sequence” on
page 115 occurs.
114
Advanced User Guide
5
Methods and Sequences
Ready wait
If a sequence is started but the instrument is not ready (due to
oven temperature, equilibration times, etc.), the sequence will
not start until all instrument setpoints are ready
To pause and resume a sequence
Press [Seq Control], scroll to Pause sequence, and press [Enter].
The sequence status changes to paused, and you are given the
option to resume or stop the paused sequence.
The sequence halts when the current sample run is complete.
To continue the paused sequence, scroll to Resume sequence and
press [Enter]. When a sequence is resumed, it starts with the
next sample.
To stop a sequence
A sequence automatically stops at the end of the last active
subsequence unless Repeat sequence is On in the Post Sequence
events.
To stop a running sequence, scroll to Stop sequence and press
[Enter]. A stopped sequence can only be restarted from the
beginning.
To abort a sequence
When a sequence is aborted, it stops immediately without
waiting for the current run to finish. These actions will cause a
sequence to abort:
• A run is stopped by pressing [Stop].
• A sampler error occurs producing an error message.
• The GC detects a configuration mismatch during a method
load.
• A running sequence tries to load an empty method.
• The sampler is turned off. You can correct the problem and
then resume the sequence. The aborted sample run will be
repeated.
Advanced User Guide
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5
116
Methods and Sequences
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
6
Checking for Leaks
Preparing the GC for Maintenance 118
To Check for External Leaks 120
To Check for GC Leaks 121
Leaks in Capillary Column (Microfluidic) Fittings 122
To Perform a SS Inlet Pressure Decay Test 123
To Correct Leaks in the Split Splitless Inlet 127
To Perform a Multimode Inlet Pressure Decay Test 128
To Correct Leaks in the Multimode Inlet 132
To Perform a SS Inlet Pressure Decay Test 123
To Correct Leaks in the Packed Column Inlet 137
To Perform a COC Pressure Decay Test 138
To Correct Leaks in the Cool On-Column Inlet 141
To Perform a PTV Pressure Decay Test 142
To Correct Leaks in the PTV Inlet 146
To Perform a VI Pressure Decay Test 147
To Prepare the VI for a Closed System Leak Check 150
To Correct Leaks in the Volatiles Interface 151
Agilent Technologies
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6
Checking for Leaks
Preparing the GC for Maintenance
Before most maintenance procedures, the GC must be made
ready. The purpose of this preparation is to avoid damage to
both the instrument (electronics, columns, etc.) and the user
(shocks, burns).
Column and oven preparation
The main hazards here are temperature (burns) and column
exposure to air.
• Cool the oven by changing its setpoint to 35 °C. This allows
the oven fan to assist cooling.
• Leave the carrier gas flow On until the oven has cooled. This
protects the column from oxygen damage.
Inlet preparation
We are concerned with the possibility of burns and air intrusion
into the column.
• After the oven and columns have cooled, reduce all inlet
flows to 0.0 and turn the temperatures Off.
• For inlet- only maintenance, leave all detectors at their
normal setpoints except for the TCD filament, which should
be turned Off.
• If the column is to be removed, cap both ends to keep air out.
Detector preparation
This is another burn hazard area, plus the possibility of damage
to the very sensitive electronics.
Some detectors (uECD, FPD, NPD) require 12 hours or longer to
stabilize from the detector- off condition.
• To cool the detector, reduce the temperature setpoint to
35 °C.
• Some detectors (FID, NPD, FPD) use high voltages. The high
voltage supply is part of the electrometer. Turn it Off to
disable the high voltage.
• The filament in the TCD will be damaged if exposed to air
while hot. To protect the filament, turn it Off.
118
Advanced User Guide
6
Checking for Leaks
Leak Check Tips
When checking for leaks, consider the system in two parts:
external leak points and GC leak points.
• External leak points include the gas cylinder (or gas
purifier), regulator and its fittings, supply shutoff valves, and
connections to the GC supply fittings.
• GC leak points include inlets, detectors, column
connections, valve connections, and connections between
flow modules and inlets/detectors.
WA R N I N G
Hydrogen (H2) is flammable and is an explosion hazard when
mixed with air in an enclosed space (for example, a flow meter).
Purge flowmeters with inert gas as needed. Always measure
gases individually. Always turn off detectors to prevent
flame/bead autoignition.
WA R N I N G
Hazardous sample gases may be present.
1 Gather the following:
• Electronic leak detector capable of detecting the gas type
• 7/16, 9/16, and 1/4- inch wrenches for tightening
Swagelok and column fittings
2
Check any potential leak points associated with any
maintenance recently performed.
3
Check GC fittings and connections that undergo thermal
cycling, since thermal cycling tends to loosen some fitting
types. Use the electronic leak detector to determine if a
fitting is leaking.
• Start by checking any newly made connections.
• Remember to check connections in the gas supply lines
after changing traps or supply cylinders.
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To Check for External Leaks
Check for leaks at these connections:
• Gas supply bulkhead fittings
• Gas cylinder fitting
• Regulator fittings
• Traps
• Shut- off valves
• T- fittings
Perform a pressure drop test.
1 Turn off the GC.
120
2
Set the regulator pressure to 415 kPa (60 psi).
3
Fully turn the regulator knob counterclockwise to shut the
valve.
4
Wait 5 minutes. If there is a measurable drop in pressure,
there is a leak in the external connections. No drop in
pressure indicates that the external connections are not
leaking.
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Checking for Leaks
To Check for GC Leaks
Check for leaks at these connections:
• Inlet septum, septum head, liner, split vent trap, split vent
trap line, and purge vent fittings
• Column connections to inlets, detectors, valves, splitters, and
unions
• Fittings from the flow modules to the inlets, detectors, and
valves
• Column adapters
• Agilent capillary flow fittings
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6
Checking for Leaks
Leaks in Capillary Column (Microfluidic) Fittings
For capillary column fittings, a leak usually indicates that the
fitting has been overtightened. Unless the fitting is obviously
loose, do not tighten it further. Instead, remove the connection,
trim the column end, and install it again.
Also inspect the plate and connection for a broken column tip.
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Checking for Leaks
To Perform a SS Inlet Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the septum nut, column adapter, column
connection, and so forth.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
The test can find leaks at the:
The test cannot find leaks at the:
septum
column fitting
septum nut
gas supply bulkhead fittings to the
flow module
liner O-ring seal
tubing and connections in a transfer
line connected to the inlet
gold seal/washer and reducing nut
internal leaks in an EPC module
(septum purge valve)
inlet body
flow manifold split vent valve
flow manifold septum purge valve
split vent tubing and trap
septum purge tubing
seals within the tubing between the
inlet flow module and the inlet body
1 Gather the following (see Consumables and parts for the
split/splitless inlet):
• No- hole ferrule
• 1/4- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• Column nut
• New septum
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• O- ring
• ECD/TCD Detector plug (part no. 5060- 9055)
2
Load the inlet maintenance method and wait for the GC to
become ready.
3
Remove the column, if installed.
4
Plug the column fitting with a column nut and a no- hole
ferrule.
5
Remove the old septum and replace it with a new one. See To
change the septum on the split/splitless inlet.
6
Inspect the O- ring and replace it if it is hard and brittle or
cracked. See To change the liner and O- ring on the
split/splitless inlet.
7
Set the inlet to Split Mode.
8
Configure the column as Inlet: Unspecified.
9
Set the inlet temperature to 70 °C.
10 Set the Total flow to 60 mL/min.
11 Enter a pressure setpoint of 25 psi (172 kPa). Make sure that
the pressure supplied to the GC is at least 10 psi (70 kPa)
higher than the inlet pressure.
12 If pressure cannot be achieved, there is either a large leak or
the supply pressure is too low.
13 Set the Septum purge flow to 3.0 mL/min.
14 Cap the septum purge fitting with the ECD/TCD detector
plug.
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Checking for Leaks
Back inlet purge
vent
Back inlet split
vent
Front inlet split
vent
Front inlet
purge vent
Front purge vent shown plugged
15 From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
16 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
17 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
18 Quickly turn off the carrier gas supply at its source.
19 Monitor the pressure for 10 minutes. Use the timer by
pressing [Time] and [Enter].
A pressure drop of less than 0.5 psig (0.05 psi/min or less;
3.4 kPa or 0.34 kPa/min) is acceptable.
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6
Checking for Leaks
If the pressure drops much faster than the acceptable rate,
see “To Correct Leaks in the Split Splitless Inlet”. Retest.
Note that liner size impacts pressure drop. An inlet with a
smaller volume liner does not tolerate as large a leak rate as
an inlet with a larger volume liner.
20 After the inlet passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
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Checking for Leaks
To Correct Leaks in the Split Splitless Inlet
If the inlet fails a pressure decay test, check the following:
• Check the caps/plugs used in the test—make sure each is
correctly installed and tight.
• If you performed the leak test after performing maintenance,
check for proper installation of the part(s) handled during
the maintenance.
• Check the tightness of the septum nut. See To change the
septum on the split/Splitless inlet.
• Check the septum. Replace if old or damaged.
• Check the insert assembly installation.
• Check the liner and liner O- ring. See To change the liner and
O- ring on the split/splitless inlet.
• If you changed the gold seal, verify correct installation. See
To replace the gold seal on the split/splitless inlet.
If these items do not resolve the problem, contact Agilent for
service.
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6
Checking for Leaks
To Perform a Multimode Inlet Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the septum nut, column adapter, column
connection, and so forth.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
The test can find leaks at the:
The test cannot find leaks at the:
septum
column fitting
septum nut
gas supply bulkhead fittings to the
flow module
liner O-ring seal
tubing and connections in a transfer
line connected to the inlet
inlet body
flow manifold split vent valve
flow manifold septum purge valve
split vent tubing and trap
septum purge tubing
seals within the tubing between the
inlet flow module and the inlet body
1 Gather the following (see Consumables and parts for the
Multimode inlet):
• No- hole ferrule
• 1/4- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• Column nut
• New septum
• O- ring
• ECD/TCD Detector plug (part no. 5060- 9055)
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Checking for Leaks
2
Load the inlet maintenance method and wait for the GC to
become ready.
3
Remove the column, if installed.
4
Plug the column fitting with a column nut and a no- hole
ferrule.
5
Remove the old septum and replace it with a new one. See To
change the septum on the multimode inlet.
6
Inspect the O- ring and replace it if it is hard and brittle or
cracked. See To change the liner and O- ring on the
Multimode inlet.
7
Set the inlet to Split Mode.
8
Configure the column as Inlet: Unspecified.
9
Set the inlet temperature to 70 °C.
10 Set the Total flow to 60 mL/min.
11 Enter a pressure setpoint of 25 psi (172 kPa). Make sure that
the pressure supplied to the GC is at least 10 psi (70 kPa)
higher than the inlet pressure.
12 If pressure cannot be achieved, there is either a large leak or
the supply pressure is too low.
13 Set the Septum purge flow to 3.0 mL/min.
14 Cap the septum purge fitting with the ECD/TCD detector
plug.
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6
Checking for Leaks
Back inlet purge
vent
Back inlet split
vent
Front inlet split
vent
Front inlet
purge vent
Front purge vent shown plugged
15 From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
16 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
17 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
18 Quickly turn off the carrier gas supply at its source.
19 Monitor the pressure for 10 minutes. Use the timer by
pressing [Time] and [Enter].
A pressure drop of less than 0.5 psig (0.05 psi/min or less;
3.4 kPa or 0.34 kPa/min) is acceptable.
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Checking for Leaks
If the pressure drops much faster than the acceptable rate,
see “To Correct Leaks in the Multimode Inlet”. Retest.
Note that liner size impacts pressure drop. An inlet with a
smaller volume liner does not tolerate as large a leak rate as
an inlet with a larger volume liner.
20 After the inlet passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
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6
Checking for Leaks
To Correct Leaks in the Multimode Inlet
If the inlet fails a pressure decay test, check the following:
• Check the caps/plugs used in the test—make sure each is
correctly installed and tight.
• If you performed the leak test after performing maintenance,
check for proper installation of the part(s) handled during
the maintenance.
• Check the tightness of the septum nut. See To change the
septum on the Multimode inlet.
• Check the septum. Replace if old or damaged.
• Check the insert assembly installation.
• Check the liner and liner O- ring. See To change the liner and
O- ring on the Multimode inlet.
If these items do not resolve the problem, contact Agilent for
service.
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Checking for Leaks
To Perform a PP Inlet Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the septum nut, column adapter, column
connection, and so forth.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
The test can find leaks at the:
The test cannot find leaks at the:
septum
column fitting
septum nut
gas supply bulkhead fittings to the
flow module
glass insert O-ring seal
adapter and ferrule
inlet body
top insert weldment
seals within the tubing between the
inlet flow module and the inlet body
1 Gather the following (see Consumables and parts for the
purged packed inlet):
• No- hole ferrule
• 1/4- inch wrench
• 7/16- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• 9/16- inch wrench
• 1/8- and 1/4- inch Swagelok caps
• ECD/TCD Detector plug (part no. 5060- 9055)
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2
Load the inlet maintenance method and wait for the GC to
become ready.
3
Remove the column, if installed.
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Checking for Leaks
4
Plug the column fitting.
• If the capillary column adapter is installed, use a column
nut and a no- hole ferrule
• If a 1/8- inch packed column adapter is installed, use a
1/8- inch Swagelok cap (5180- 4121).
• If a 1/4- inch packed column adapter is installed, use a
1/4- inch Swagelok cap (5180- 4120)
5
Remove the old septum and replace it with a new one. See To
change the septum on the purged packed inlet.
6
Inspect the O- ring and replace it if it is hard and brittle or
cracked. See To change the O- ring on the purged packed
inlet.
7
If unsure of the quality of the adapter ferrule, replace it. See
To change the glass insert on a PP inlet.
8
Configure, but do not install, a capillary column to put the
inlet in pressure control mode.
9
Set the inlet temperature to 100 °C.
10 Enter a pressure setpoint of 25 psi (172 kPa). Make sure that
the pressure supplied to the GC is at least 10 psi (70 kPa)
higher than the inlet pressure.
11 If pressure cannot be achieved, there is either a large leak or
the supply pressure is too low.
12 Set the Septum purge flow to 3.0 mL/min.
13 Cap the septum purge fitting with the ECD/TCD detector
plug.
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Checking for Leaks
Back inlet purge
vent
Back inlet split
vent
Front inlet split
vent
Front inlet
purge vent
Front purge vent shown plugged
14 From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
15 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
16 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
17 Quickly turn off the carrier gas supply at its source.
18 Monitor the pressure for 10 minutes. Use the timer by
pressing [Time] and [Enter].
A pressure drop of less than 0.7 psig (0.07 psi/min or less;
4.8 kPa or 0.48 kPa/min) is acceptable.
If the pressure drops much faster than the acceptable rate,
see “To Correct Leaks in the Packed Column Inlet”. Retest.
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Checking for Leaks
19 After the inlet passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
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Checking for Leaks
To Correct Leaks in the Packed Column Inlet
If the inlet fails a pressure decay test, check the following:
• Check the caps/plugs used in the test—make sure each is
correctly installed and tight.
• If you performed the leak test after performing maintenance,
check for proper installation of the part(s) handled during
the maintenance.
• Check the tightness of the septum nut. See To change the
septum on the purged packed inlet.
• Check the septum. Replace if old or damaged.
• Check that the top insert weldment is installed tightly.
• Replace the O- ring. See To change the O- ring on the purged
packed inlet. Also check the glass insert. See To change the
glass insert on a PP inlet.
• Replace the ferrule seal on the adapter.
If these items do not resolve the problem, contact Agilent for
service.
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Checking for Leaks
To Perform a COC Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the septum nut, column adapter, column
connection, and so forth. See “To Check for External Leaks”.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
The test can find leaks at the:
The test cannot find leaks at the:
septum
column fitting
septum nut or cooling tower
gas supply bulkhead fittings to the
flow module
seals within the tubing between the
inlet flow module and the inlet body
inlet body
1 Gather the following (see Consumables and parts for the
COC inlet):
• No- hole ferrule
• 1/4- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• Column nut
• New septum
• ECD/TCD Detector plug (part no. 5060- 9055)
138
2
Load the inlet maintenance method and wait for the GC to
become ready.
3
Remove the column, if installed.
4
Plug the column fitting with a column nut and no- hole
ferrule.
5
Remove the old septum and replace it with a new one. See To
change a septum on the COC inlet.
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6
Checking for Leaks
Back inlet split
vent
6
Enter a pressure setpoint of 25 psi (172 kPa). Make sure that
the pressure supplied to the GC is at least 10 psi (70 kPa)
higher than the inlet pressure.
7
Wait 5 minutes for the pressure to equilibrate. If pressure
cannot be achieved, there is either a large leak or the supply
pressure is too low.
8
Set the Septum purge flow to 3.0 mL/min.
9
Cap the septum purge fitting with the ECD/TCD detector
plug.
Back inlet purge
vent
Front inlet split
vent
Front inlet
purge vent
Front purge vent shown plugged
10 From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
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Checking for Leaks
11 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
12 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
13 Quickly turn off the carrier gas supply at its source.
14 Monitor the pressure for 10 minutes. Use the timer by
pressing [Time] and [Enter].
A pressure drop of less than 1.0 psig (0.1 psi/min or less;
6.9 kPa or 0.69 kPa/min) is acceptable.
If the pressure drops much faster than the acceptable rate,
see “To Correct Leaks in the Cool On- Column Inlet”. Retest.
15 After the inlet passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
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Checking for Leaks
To Correct Leaks in the Cool On-Column Inlet
If the inlet fails a pressure decay test, check the following:
• Check the caps/plugs used in the test—make sure each is
correctly installed and tight.
• If you performed the leak test after performing maintenance,
check for proper installation of the part(s) handled during
the maintenance.
• Check the tightness of the septum nut or cooling tower
assembly. See To change a septum nut or cooling tower and
septum on a COC inlet.
• Check the septum. Replace if old or damaged.
If these items do not resolve the problem, contact Agilent for
service.
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Checking for Leaks
To Perform a PTV Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the septum nut, column adapter, column
connection, and so forth.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
The test can find leaks at the:
The test cannot find leaks at the:
septum
column fitting
septum nut
gas supply bulkhead fittings to the
flow module
liner O-ring seal
tubing and connections in a transfer
line connected to the inlet
gold seal/washer and reducing nut
inlet body
flow manifold split vent valve
flow manifold septum purge valve
split vent tubing and trap
septum purge tubing
seals within the tubing between the
inlet flow module and the inlet body
1 Gather the following (see Consumables and parts for the PTV
inlet):
• No- hole ferrule
• 1/4- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• Column nut
• New septum
• New Graphpak 3D ferrule and liner
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Checking for Leaks
• ECD/TCD Detector plug (part no. 5060- 9055)
2
Load the inlet maintenance method and wait for the GC to
become ready.
3
Remove the column, if installed.
4
Plug the column fitting with a column nut and a no- hole
ferrule.
5
If using the septum head, and the quality of the septum (or
Microseal) and GRAPHPACK- 3D ferrule on the glass liner
are unknown, replace them now. See To change the septum
on the PTV inlet and To change the liner on the PTV inlet.
6
Set the inlet to Split Mode.
7
Configure the column as 0 length.
8
Set the inlet temperature to 100 °C.
9
Set the Total flow to 60 mL/min.
10 Enter a pressure setpoint of 25 psi (172 kPa). Make sure that
the pressure supplied to the GC is at least 10 psi (70 kPa)
higher than the inlet pressure.
11 If pressure cannot be achieved, there is either a large leak or
the supply pressure is too low.
12 Set the Septum purge flow to 3.0 mL/min.
13 Cap the septum purge fitting with the ECD/TCD detector
plug.
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Checking for Leaks
Back inlet split
vent
Back inlet purge
vent
Front inlet split
vent
Front inlet
purge vent
Front purge vent shown plugged
14 From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
15 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
16 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
17 Quickly turn off the carrier gas supply at its source.
18 Monitor the pressure for 10 minutes. Use the timer by
pressing [Time] and [Enter].
A pressure drop of less than 0.5 psig (0.05 psi/min or less;
3.4 kPa or 0.34 kPa/min) is acceptable.
If the pressure drops much faster than the acceptable rate,
see “To Correct Leaks in the PTV Inlet”. Retest.
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Checking for Leaks
Note that liner size impacts pressure drop. An inlet with a
smaller volume liner does not tolerate as large a leak rate as
an inlet with a larger volume liner.
19 After the inlet passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
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Checking for Leaks
To Correct Leaks in the PTV Inlet
If the inlet fails a pressure decay test, check the following:
• Check the caps/plugs used in the test—make sure each is
correctly installed and tight.
• If you performed the leak test after performing maintenance,
check for proper installation of the part(s) handled during
the maintenance.
• If using a septum head, check the tightness of the septum
nut. See To change the septum on the PTV inlet.
• If using a septum head, check the septum. Replace if old or
damaged.
• Check that the septumless- or septum- head assembly is
installed tightly.
• Replace the liner and Graphpak 3D ferrule. See To change
the liner on the PTV inlet.
• Check the Graphpak adapter seal against the inlet body.
Replace the silver seal and reinstall the adapter if needed.
See To replace the inlet adapter for the PTV inlet.
• If using the septumless head, check for leaks around the
guide cap. Replace the Teflon ferrule in the guide cap. See To
replace the Teflon ferrule on a PTV inlet.
• Check for leaks at the split vent trap. Tighten as necessary.
Replace the split vent trap filter and O- rings. See To replace
the filter in the PTV inlet split vent line.
If these items not resolve the problem, contact Agilent for
service.
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Checking for Leaks
To Perform a VI Pressure Decay Test
The pressure decay test checks for leaks from the inlet flow
module up to the column fitting.
Initially test the VI with a sampling system installed. If the
system fails the leak test, then isolate the VI from the sampler as
described in “To Prepare the VI for a Closed System Leak
Check” on page 150.
After performing maintenance, first check for leaks in
externally accessible areas. See “To Check for External Leaks”.
If a leak is known to exist, check the externally accessible inlet
fittings first, especially any connection that has seen recent
maintenance, such as the column connection, split vent line,
and so forth.
The pressure decay leak test described below requires removing
the column and capping the inlet column fitting. This test
can/cannot find the following types of leaks:
The test can find leaks at the:
The test cannot find leaks at the:
sampler connection
column fitting
pressure sensing line connection to
the interface
gas supply bulkhead fittings to the
flow module
split vent line connection to the
interface
tubing and connections in a transfer
line connected to the inlet
the connected sampler’s entire sample
flow path
flow manifold split vent valve
flow manifold septum purge valve
split vent tubing and trap
1 Gather the following (see Consumables and parts for the VI):
• No- hole ferrule
• 1/4- inch wrench
• Heat- resistant gloves (if the inlet is hot)
• Long column nut
• ECD/TCD Detector plug (part no. 5060- 9055)
2
Advanced User Guide
Load the inlet maintenance method and wait for the GC to
become ready.
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Checking for Leaks
3
Remove the column, if installed.
4
Plug the column fitting with a column nut and a no- hole
ferrule.
5
Set the inlet to Split Mode.
6
Configure the column as 0 length.
7
Set the inlet temperature to 100 °C.
8
Set the Total flow to 60 mL/min.
9
Enter a pressure setpoint of 25 psi (172 kPa). Make sure that
the pressure supplied to the GC is at least 10 psi (70 kPa)
higher than the inlet pressure.
10 If pressure cannot be achieved, there is either a large leak or
the supply pressure is too low.
11 Set the Septum purge flow to 3.0 mL/min.
12 Cap the septum purge fitting with the ECD/TCD detector
plug.
Back inlet split
vent
Back inlet purge
vent
Front inlet split
vent
Front inlet
purge vent
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Checking for Leaks
Front purge vent shown plugged
13 From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
14 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
15 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
16 Quickly turn off the carrier gas supply at its source.
17 Monitor the pressure for 10–15 minutes. Use the timer by
pressing [Time] and [Enter].
The pressure should drop approximately 1 psi (6.9 kPa)
during the first 1 to 2 minutes. After an initial pressure drop
of about 1 psi, the pressure should not drop more than
0.03 psi/min (0.21 kPa/min).
If the pressure drop is 0.03 psi/min or less, you can consider
the interface- gas sampler system leak- free.
If the pressure drops faster than the acceptable rate, you
must check the interface and sampler systems separately to
determine the source of the leak. See “To Prepare the VI for a
Closed System Leak Check” to create a closed flow system,
then return to this section and complete steps 10 to 15.
If you find a leak in the interface, refer to “To Correct Leaks
in the Volatiles Interface”.
If the interface is leak- free, pressure check the sampling
device. See the operating manual for your sampler for
instructions.
18 After the VI passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• If needed, reconnect the sampling device.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
Advanced User Guide
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6
Checking for Leaks
To Prepare the VI for a Closed System Leak Check
To leak check the interface independently of the gas sampling
device, you must disconnect the sampler from the interface to
isolate the interface flow system from the sampler.
WA R N I N G
Be careful! The oven and/or inlet may be hot enough to cause
burns. If either is hot, wear heat-resistant gloves to protect your
hands.
1 Gather the following:
• 1/16- inch nut for transfer line
• Ferrule for transfer line
• Heat- resistant gloves (if the inlet is hot)
150
2
Disconnect the transfer line from the interface.
3
Disconnect the carrier line from the sampler.
4
Prepare the end of the carrier line using a 1/16- inch male
nut and ferrule.
5
Connect the carrier line to the interface where you removed
the transfer line and tighten the nut finger tight. Tighten an
additional 1/4 to 1/2 turn with the 1/4- inch wrench.
6
Return to “To Perform a VI Pressure Decay Test” and repeat
steps 9 to 15.
Advanced User Guide
Checking for Leaks
6
To Correct Leaks in the Volatiles Interface
If the inlet fails a pressure decay test, check the following:
• The caps and plugs used in the test—make sure each is
correctly installed and tight.
• If you performed the leak test after performing maintenance,
check for proper installation of the part(s) handled during
the maintenance.
• The split vent and pressure sensing connections at the
interface.
• The sampler connection to the interface.
• The sampler.
If these items do not resolve the problem, contact Agilent for
service.
Advanced User Guide
151
6
152
Checking for Leaks
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
7
Flow and Pressure Modules
About Flow and Pressure Control 154
Maximum operating pressure 154
PIDs 155
Inlet Modules 156
Detector Modules 157
Pressure Control Modules 158
Auxiliary Pressure Controllers 161
Restrictors 162
1. Using an Aux epc channel to supply purge gas to a splitter 163
2. Using the PCM channels 163
Agilent Technologies
153
7
Flow and Pressure Modules
About Flow and Pressure Control
The GC uses four types of electronic flow or pressure
controllers; inlet modules, detector modules, pressure control
modules (PCMs), and auxiliary pressure controllers (Aux
EPCs).
All of these modules mount in the slots at the top rear of the GC.
The slots are identified by numbers, as shown here.
Slot 5
Slot 6
Slot 3
Slot 1
Slot 4
Slot 2
Split vent traps
and valves
Back of GC
When a module is installed in a slot, it must be connected to the
communications buss that runs underneath it. Each branch of
the buss has an identifying label near the connector. The proper
branch must be connected to the module for the firmware to
recognize it.
Branch/slot assignments are:
EPC5
EPC3
EPC1
EPC6
EPC4
EPC2
Split vent traps
and valves
Back of GC
If a detector is mounted in the left side carrier (as seen from the
front side of the oven), it is controlled by EPC6. An extension
cable connects to EPC6, runs across the top of the oven just in
front of the top row of slots, and passes through an opening into
the detector carrier.
Maximum operating pressure
The pneumatics modules of the GC will stand over 250 psi
pressure, but may not function reliably. We recommend a
maximum continuous operating pressure of 170 psi to avoid
excessive wear and leaks.
154
Advanced User Guide
7
Flow and Pressure Modules
PIDs
The behavior of a pressure control module is governed by a set
of three constants, called P (proportional), I (integral), and D
(differential).
Certain gases or special applications (such as QuickSwap,
headspace vial pressurization, or splitter and backflush
applications) require different PIDs than those provided at the
factory.
If you need to update or change the pneumatic PID values for an
application, use the utility program on the documentation and
utility DVD provided with the GC.
The table summarizes custom PID values required for selected
applications. Note that if you are updating an AUX EPC module,
you will need to change the frit for the channel used.
Table 23
PIDs and frits
Application
Module
AUX frit
Select Available PID
Values
QuickSwap
AUX EPC
Brown, 1 ring
Quickswap
Purged splitter and Deans Switch
when using backflush
AUX EPC
No color or rings
Quickswap
Purged splitter and Deans Switch
AUX EPC
Brown, 1 ring
Standard
Headspace vial pressurization
AUX EPC
No color or rings
AUX_EPC_Headspace
Headspace sampling loop
PCM in backpressure
control
Advanced User Guide
PCM_Headspace
155
7
Flow and Pressure Modules
Inlet Modules
These modules are used with specific inlets. They provide a
controlled flow or pressure of carrier gas to the inlet and
control the septum flow rate.
Module locations depend on the type of module and the length
of the tubing connecting it to the inlet.
If you have a Front inlet, its flow module must go in Slot 1.
If you have a Back inlet, its flow module must go in Slot 2.
156
Advanced User Guide
7
Flow and Pressure Modules
Detector Modules
These are specific to the detector with which they are supplied,
and differ according to the needs of that detector. For example,
the FID module must supply controlled amounts of air,
hydrogen, and makeup gas. The TCD module supplies the
reference and makeup gases, but includes the reference
switching valve that is essential to detector operation.
Module locations depend on the type of module and the length
of the tubing connecting it to the detector.
If you have a Front detector, its flow module must go in Slot 3.
If you have a Back detector, its flow module must go in Slot 4.
If you have a TCD detector mounted on the left side of the GC,
its flow module mounts in a special bracket near the detector.
Advanced User Guide
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7
Flow and Pressure Modules
Pressure Control Modules
The PCM is a general purpose module with two independent
control channels, designated 1 and 2. The general name of a
PCM module is PCM #, where the # (actually, a letter) identifies
the PCM (there can be up to 3 installed).
The two channels are not identical. Channel 1 is a simple
forward- pressure regulated channel that maintains constant
flow through a fixed restrictor.
Channel 2 may be used either as a forward- pressure regulator
or as a back- pressure regulator, simply by reversing the input
and output connections. The back pressure mode can be very
useful with a gas sampling valve, where it ensures that the
sample pressure in the loop remains constant.
158
Advanced User Guide
7
Flow and Pressure Modules
For channel 1, gas input is via a threaded fitting. Gas output is
via a coil of metal tubing with a Swagelok fitting on the end.
For channel 2, the connections are the same as for channel 1 if
channel 2 is to be used as a forward- pressure regulator. They
are reversed—extra fittings/adapters will be needed—if it is to be
used as a back- pressure regulator.
PCMs can be installed in several locations:
• In slot 1. The name is PCM A.
• In slot 2. The name is PCM B.
• In slot 5. If there are no PCMs in slots 1 and 2, the name is
PCM A. If another PCM is installed in either slot 1 or 2, the
PCM in slot 5 takes the name that is not being used (A or B).
If PCMs are installed in both slots 1 and 2, the name is PCM C.
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7
Flow and Pressure Modules
• In slot 6. The name is always PCM C.
PCM A or B
PCM C
Slot 3
Slot 4
PCM A
PCM B
Split vent trap
and valve
Back of GC
Both channels of a PCM are controlled by the same parameter
list. The first two lines refer to channel 1, the remaining lines
refer to channel 2.
160
Advanced User Guide
7
Flow and Pressure Modules
Auxiliary Pressure Controllers
The Auxiliary Pressure Controller (Aux epc) is also a general
purpose device. It has three independent forward- pressure
regulated channels. Channels are designated by numbers 1
through 9 (there can be up to 3 Aux epcs), depending on where
the module is installed.
If an auxiliary channel is specified as the Inlet during column
configuration, that channel allows run time programming and
three- ramp flow or pressure programming.
Gas input is via threaded fittings. Gas output is via coils of
metal tubing with Swagelok fittings on the ends.
As you look at the module from the back of the GC, the channels
are numbered from left to right according to this scheme:
• In slot 6. The name is Aux epc #, where # is 1, 2, or 3 and
identifies the channel.
• In slot 5. The name is Aux epc #, where # is 4, 5, or 6 and
identifies the channel.
• In slot 4. The name is Aux epc #, where # is 7, 8, or 9 and
identifies the channel.
• In the third detector side of the GC. The name is Aux epc #,
where # is 7, 8, or 9 and identifies the channel.
Aux epc 4, 5, 6
Slot 3
Slot 1
Aux epc 1, 2, 3 Aux epc 7, 8, 9
Slot 2
Split vent trap
and valve
Back of GC
Advanced User Guide
161
7
Flow and Pressure Modules
Restrictors
Both PCMs and auxiliary channels are controlled by pressure
setpoints. To work properly, there must be adequate flow
resistance downstream of the pressure sensor. Each channel
provides a frit- type restrictor. Four frits are available.
Table 24
Auxiliary channel frits
Frit marking
Flow resistance
Flow characteristic
Often used with
Three blue rings
High
3.33 ± 0.3 SCCM @ 15 PSIG
FID Air, QuickSwap,
Splitter, Deans Switch
Two red rings
Medium
30 ± 1.5 SCCM H2 @ 15 PSIG
FID Hydrogen
One brown ring
Low
400 ± 30 SCCM AIR @ 40 PSIG
NPD Hydrogen
None (brass tube)
Zero
No restriction
Headspace vial
pressurization
The brown ring frit is in all channels in the AUX epc when the
instrument is shipped. No frit ships in the PCM Aux channel.
When installing or replacing a frit, always use a new O- ring
(5180- 4181, 12/pk).
Selecting a frit
The frits change the control range of the channels. The objective
is to find a frit that allows the required range of flows at
reasonable source pressures.
• For an auxiliary channel ordered as an option (part of the
GC order), use the frit supplied by the factory.
• For an auxiliary channel ordered as an accessory (separate
from the GC order), see the instruction information supplied
with the accessory.
• For a non- Agilent instrument, you must experiment to find
the appropriate frit.
When you change a frit, you change the physical characteristics
of the channel. It may be desirable (or necessary) to change the
PID constants for that channel. See “PIDs” on page 155.
162
Advanced User Guide
7
Flow and Pressure Modules
Examples
1. Using an Aux epc channel to supply purge gas to a splitter
An Aux epc channel operates only in the forward- pressure
mode; it provides a constant pressure at its outlet. It is used to
provide gas to some other device, such as a splitter with a
makeup gas input.
Aux EPC
Split/splitless inlet
µECD
0.507 m x 0.10 mm x 0 µm
FPD
MSD
0.532 m x 0.18 mm x 0 µm
1.444 m x 0.18 mm x 0 µm
30 m x 0.25 mm x 0.25 µm HP-MS5
In this configuration, the gas eluting from the column is divided
among three detectors. Because the resulting flows can be quite
small, makeup gas is added at the splitter. An Aux epc channel
provides it.
Assume that we are using channel Aux epc 1 as the makeup
source. The gas is plumbed to the leftmost (as seen from the
back of the GC) fitting on the proper module. The outlet tubing
for this channel goes to the splitter inside the oven—an
extension tube may be needed to reach this far.
The medium frit is probably appropriate for this application.
Rather than have the makeup gas flowing all the time, consider
turning it on and off with run time commands.
2. Using the PCM channels
The two channels in a PCM are different. Channel 1 is used to
supply a pressure. Channel 2 may be used in the same way, but
can also be used to maintain a pressure by reversing the input
and output connections.
Advanced User Guide
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7
Flow and Pressure Modules
Channel 1: Forward-pressure only
This is identical to the carrier gas channel for the packed
column inlet.
Channel 2: Two-way channel
If gas is supplied at the threaded connection and delivered by
the tubing, this operates the same as channel 1. But the
connections can be reversed—requiring some fittings—so that it
will maintain the gas supplied to it at a fixed pressure. In this
mode it behaves as a controlled leak.
This can be used to maintain the gas in a gas sampling valve at a
fixed pressure, even if the supply varies somewhat. The result is
improved reproducibility in sample amount.
The figure shows the connections with the valve in the Load
position.
To column
Carrier in
Back-pressure regulation
Valve
Sample in
Threaded
connection
Sample out
164
PS
Vent
connection
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
8
Inlets
Using Hydrogen 167
Inlet Overview 168
Carrier Gas Flow Rates 169
About Gas Saver 170
Pre Run and Prep Run 171
Auto Prep Run 172
About Heaters 173
About the Split/Splitless Inlet 175
Split/Splitless inlet split mode overview 176
Split/Splitless inlet splitless mode overview 177
The S/SL inlet pulsed split and splitless modes 178
Split/Splitless inlet split mode minimum operating pressures 179
Selecting the correct S/SL inlet liner 180
Vapor Volume Calculator 182
Selecting parameters for the S/SL splitless mode 183
About the Multimode Inlet 186
Septum tightening (MMI) 186
Heating the MMI 187
Cooling the MMI 187
MMI split mode minimum operating pressures 188
Selecting the correct MMI liner 189
Vapor Volume Calculator 191
MMI split and pulsed split modes 191
MMI splitless and pulsed splitless modes 194
MMI solvent vent mode 201
MMI Direct Mode 209
To develop a MMI method that uses large volume injection 210
Multiple injections with the MMI 213
About the Cool On-Column Inlet 222
Retention gaps 223
COC inlet temperature control 223
Setting COC inlet flows/pressures 224
About the PTV Inlet 226
PTV sampling heads 226
Heating the PTV inlet 227
Agilent Technologies
165
8
Inlets
Cooling the PTV inlet 228
PTV inlet split and pulsed split modes 228
PTV inlet splitless and pulsed splitless modes 232
PTV inlet solvent vent mode 239
To develop a PTV method that uses large volume injection 247
Multiple injections with the PTV inlet 250
About the Volatiles Interface 255
About the VI split mode 257
About the VI splitless mode 261
About the VI direct mode 266
Preparing the Interface for Direct Sample Introduction 269
Setting parameters for the VI direct mode 272
166
Advanced User Guide
Inlets
8
Using Hydrogen
WA R N I N G
When using hydrogen (H2), as the carrier gas, be aware that
hydrogen (H2) gas can flow into the oven and create an explosion
hazard. Therefore, be sure that the supply is off until all
connections are made, and ensure that the inlet and detector
column fittings are either connected to a column or capped at all
times when hydrogen (H2) gas is supplied to the instrument.
WA R N I N G
Hydrogen (H2) is flammable. Leaks, when confined in an enclosed
space, may create a fire or explosion hazard. In any application
using hydrogen (H2), leak test all connections, lines, and valves
before operating the instrument. Always turn off the hydrogen
(H2) supply at its source before working on the instrument.
Advanced User Guide
167
8
Inlets
Inlet Overview
Table 25
Comparing inlets
Inlet
Column
Mode
Sample
concentration
Split/splitless
Capillary
Split
Pulsed split
High
High
Splitless
Pulsed splitless
Low
Low
Split
Pulsed split
Splitless
Pulsed splitless
Solvent vent
High
High
Low
Low
Low
Multimode
Capillary
Comments
Useful with large
injections
Useful with large
injections
Sample
to column
Very little
Very little
All
All
Very little
Very little
All
All
Multiple injections Most
concentrate
analytes and
vent solvent
All
Direct
Capillary
n/a
Low or labile
Packed column
Packed
Large capillary
n/a
n/a
Any
Any
Programmed
temperature
vaporization
Capillary
Split
Pulsed split
Splitless
Pulsed splitless
Solvent vent
High
High
Low
Low
Low
Very little
Very little
All
All
Multiple injections Most
concentrate
analytes and
vent solvent
Volatiles interface
(for use with
external volatiles
sampler)
Capillary
Direct
Split
Splitless
Low
High
Low
Lowest dead
volume
Max flow = 100
mL/min
168
Minimal
discrimination
and
decomposition
All
Cool on-column
OK if resolution
not critical
All
All
All
Very little
All
Advanced User Guide
Inlets
8
Carrier Gas Flow Rates
The flow rates in Table 26 are recommended for all column
temperatures.
Table 26
Column type
Column size and carrier flow rate
Column size
Carrier flow rate, mL/min
Hydrogen
Packed
Capillary
Advanced User Guide
Helium
Nitrogen
1/8-inch
30
20
1/4-inch
60
40
0.05 mm id
0.5
0.4
n/a
0.10 mm id
1.0
0.8
n/a
0.20 mm id
2.0
1.6
0.25
0.25 mm id
2.5
2.0
0.5
0.32 mm id
3.2
2.6
0.75
0.53 mm id
5.3
4.2
1.5
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8
Inlets
About Gas Saver
Gas saver reduces carrier flow from the split vent after the
sample is on the column. It applies to the Split/Splitless and
PTV inlets (all modes) and to the split and splitless modes of the
Volatiles Interface. It is most useful in split applications.
Column head pressure and flow rate are maintained, while
purge and split vent flows decrease. Flows—except column
flow—remain at the reduced level until you press [Prep Run].
[Start]
Split mode
Regular flow
[Prep Run]
50
Gas saver time, 3 min
Run ends
40
Split vent flow
mL/min
30
Gas saver flow
20 Gas saver flow
10
-2
-1
0
1
2
3
4
5
6
7
8
Time, min
[Start]
50
Splitless mode
Gas saver time, 5 min
Purge time, 2 min
[Prep Run]
40
Split vent flow
mL/min
Run ends
Purge flow
30
Gas saver flow
20 Gas saver flow
10
-2
-1
0
1
2
3
4
5
6
7
8
Time, min
The pulsed modes of the split/splitless and PTV inlets are
similar except for the pressure pulse starting at [Prep Run] and
ending at Pulse time. The solvent vent mode of the PTV is more
complex; see “PTV inlet solvent vent mode” on page 239.
To use gas saver
1 Press [Front Inlet] or [Back Inlet].
170
2
Turn gas saver On.
3
Set Gas saver flow. It must be at least 15 mL/min greater than
the column flow.
4
If in split mode, set Saver time after injection time. In all
other modes, set after Purge time.
Advanced User Guide
8
Inlets
Pre Run and Prep Run
With some inlets and operating modes, certain instrument
setpoints are different between runs than during an analysis. To
restore the setpoints for injection, you must place the GC into
the Pre Run state.
You must use the Pre Run state when:
• Using gas saver with any inlet.
• Using splitless mode with any inlet.
• Using a pressure pulse mode with any inlet.
• Using the solvent vent mode of the PTV inlet.
• Using the direct or splitless mode of the Volatiles Interface.
There are three ways to begin Pre Run—manually (press [Prep
Run] before each run), automatically (for Agilent samplers), or
using Auto Prep Run (for non- Agilent samplers). The three
methods are discussed below.
During the Pre Run state:
• The Pre Run light blinks and Not Ready is on.
• Setpoints change to the correct values for injection.
• Inlet, detector, and oven equilibration times begin.
When all equilibration times expire, the Pre Run light is on
steadily. When all criteria for a run are met, the Not Ready light
turns off. The GC is now ready for sample injection.
The [Prep Run] key
Press [Prep Run] before you inject a sample manually. The GC
enters the Pre Run state. When the Pre Run light is steady and
the Not Ready light goes off, begin the analysis.
Agilent samplers
If you are using an Agilent automatic sampling system, the
[Prep Run] function is automatic.
Start the sampler. It generates the [Prep Run] function, When all
the setpoints are reached and the GC becomes Ready, sample
injection begins.
Advanced User Guide
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8
Inlets
Non-Agilent samplers
With most automatic injection systems, you do not need to use
the [Prep Run] key. If your sampler or automation controller (for
example, an integrator or workstation) does not support the
[Prep Run] function, you must set the GC to Auto Prep Run.
Auto Prep Run
To set this parameter, usually for a non- Agilent integrator,
workstation, or other controlling device:
1 Press [Config] to view a list of configurable parameters.
172
2
Scroll to Instrument and press [Enter].
3
Scroll to Auto prep run and press [On/Yes].
Advanced User Guide
8
Inlets
About Heaters
Inlets (and detectors, valve boxes, etc.) are heated. There are six
heater connectors on the GC mainframe, located as shown here:
Front of GC
Near top right corner
of front detector board
3
Near top right corner
of back detector board
4
Left end of valve bracket
5
Right end of valve bracket
6
1
2
Near front inlet
Near back inlet
All heater connectors are square, 4- conductor receptacles
mounted on brackets.
The next table describes the heaters that are available for each
module.
Table 27
Advanced User Guide
Heater connectors by module
Module
Available heater connectors
Front inlet
1 or None
Back inlet
2 or None
Front detector
3 or 5
Back detector
4 or 6
Aux detector 1
5 or 6 or 2
Aux detector 2
None
PCM A
5 or 6 or 1 or 2
PCM B
5 or 6 or 1 or 2
PCM C
5 or 6 or 1 or 2
AUX 1,2,3
None
AUX 4,5,6
None
AUX 7,8,9
None
Valve box
5 or 6 or Both
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8
Inlets
Table 27
Heater connectors by module (continued)
Module
Available heater connectors
Aux heater 1
5
Aux heater 2
6
Front FPD uses heater connectors 3 and 5.
Back FPD uses heater connectors 4 and 6.
FPDs can be configured for one or two heater versions.
174
Advanced User Guide
8
Inlets
About the Split/Splitless Inlet
This inlet is used for split, splitless, pulsed splitless, or pulsed
split analyses. You can choose the operating mode from the inlet
parameter list. The split mode is generally used for major
component analyses, while the splitless mode is used for trace
analyses. The pulsed splitless and pulsed split modes are used
for the same type of analyses as split or splitless, but allow you
to inject larger samples.
Septum tightening (S/SL)
Septum retainer nuts must be tightened enough to obtain a good
gas seal, but not so much as to compress the septum and make it
difficult to push a syringe needle through it.
For the standard septum retainer nut, an internal spring in the
septum retainer applies pressure to the septum. For inlet
pressures up to 100 psi, tighten the retainer until the C- ring
lifts about 1 mm above the top surface. This is adequate for
most situations.
1 mm
With higher inlet pressures, tighten the septum retainer until
the C- ring stops turning, indicating that the retainer is in firm
contact with the septum.
If using a Merlin Microseal™ septum, finger tighten the septum
nut, until snug (not loose). The pressure capacity depends on
the duckbill seal used.
Standard and high-pressure versions of the S/SL inlet
The standard split/splitless inlet is rated to 100 psi pressure at
the inlet. It is appropriate for most columns. The high- pressure
inlet is rated to 150 psi pressure—it is useful with very small
diameter capillary columns that offer considerable resistance to
gas flow.
Recommended source pressures are 120 psi and 170 psi
respectively.
Advanced User Guide
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8
Inlets
To determine the version that you have, press [Front Inlet] or
[Back Inlet], scroll to the Pressure line, and press the [Info] key.
The display will show the pressure range for the inlet—either 1 to
100 psi (for the standard version) or 1 to 150 psi (for the
high- pressure version).
Split/Splitless inlet split mode overview
During a split injection, a liquid sample is introduced into a hot
inlet where it vaporizes rapidly. A small amount of the vapor
enters the column while the major portion exits from the
split/purge vent. The ratio of column flow to split vent flow is
controlled by the user. Split injections are primarily used for
high concentration samples when you can afford to lose most of
the sample out the split/purge vent. It is also used for samples
that cannot be diluted.
The split ratio is equal to the split vent flow divided by the
column flow. If the column has been configured, the desired
split ratio can be entered directly.
The pneumatics for this inlet in split mode operation are shown
in the figure below.
176
Advanced User Guide
Inlets
Carrier Supply
80 PSI
Split
8
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Split/Splitless inlet splitless mode overview
In this mode, the split vent valve is closed during the injection
and remains so while the sample is vaporized in the liner and
transferred to the column. At a specified time after injection,
the valve opens to sweep any vapors remaining in the liner out
the split vent. This avoids solvent tailing due to the large inlet
volume and small column flow rate. Specify the purge time and
purge flow rate in the inlet parameter list.
The septum purge flow may be either on at all times (Standard
mode) or on only between the purge time and the end of the run
(Switched mode).
If you are using gas saver, the gas saver time should be after the
purge time.
Advanced User Guide
177
8
Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
The S/SL inlet pulsed split and splitless modes
The pressure pulse modes increase inlet pressure just before the
beginning of a run and return it to the normal value after a
specified amount of time. The pressure pulse:
• reduces the solvent vapor volume
• reduces the risk of inlet overload
• tightens the sample band
• may allow use of a 2 mm liner, reducing the active glass area
If your chromatography is degraded by the pressure pulse, a
retention gap may help restore peak shape.
You must press [Prep Run] before doing manual injections in the
pressure pulse modes. See “Pre Run and Prep Run” on page 171
for details.
178
Advanced User Guide
Inlets
8
You can do column pressure and flow programming when in the
pressure pulse mode. However, the pressure pulse will take
precedence over the column pressure or flow ramp.
Pressure pulse
Pressure
or
Flow
Pressure or flow program
0
1
2
3
4
5
6
7
8
Split/Splitless inlet split mode minimum operating pressures
The minimum recommended inlet total flow is 20 mL/minute.
When the split/splitless inlet is operated in Split mode, there
will be a minimum pressure at which the inlet can operate.
Typically, low inlet pressures may be required for shorter, wide
bore columns. The minimum pressure is a function of carrier
gas type, total inlet flow, liner design, and possible
contamination of the split vent tube or trap.
A wide bore column requires a much lower inlet pressure than a
typical capillary column to maintain a given flow. Setting the
split ratio (total flow) too high when using a wide bore column
can create an unstable control relationship between the
pressure and flow control loops.
Advanced User Guide
179
8
Inlets
Table 28
Approximate minimum viable inlet pressures for split/splitless inlet in split mode, in psi (kPa)
Split vent flow (mL/min)
50–100
100–200
200–400
400–600
Split liners - 5183-4647, 19251-60540
2.5 (17.2)
3.5 (24.1
4.5 (31)
6.0 (41.4)
Splitless liners - 5062-3587, 5181-8818
4.0 (27.6)
5.5 (37.9)
8.0 (55.2)
11.0 (75.4)
Split liners - 19251-60540, 5183-4647
3.0 (20.7)
4.0(27.6)
—
—
Splitless liners - 5062-3587, 5181-8818
4.0 (27.6)
6.0 (41.4)
—
—
Helium and hydrogen carrier gases
Nitrogen carrier gas
These numbers are based on the resistance to flow of new, clean
inlet systems. Sample condensation in the split vent tube or a
dirty filter can make these values non- attainable.
Selecting the correct S/SL inlet liner
Split liner
A good liner for split mode operation will offer very little
restriction to the split flow path between the bottom of the liner
and the inlet gold seal and between the outside of the liner and
the inside of the injection port body. The preferred Agilent split
liner, part number 5183- 4647, incorporates a glass positioning
bead on the bottom to facilitate this. It will also incorporate
glass wool or some other source of surface area inside the liner
that provides for complete sample vaporization across the
boiling point range of the sample. Select an appropriate liner
from Table 29.
Table 29
Liner
180
Split mode liners
Description
Volume
Mode
Deactivated
Part Number
Low Pressure Drop
– Positioning Bead
870 µL
Split – Fast
Injection
Yes
5183-4647
4mm ID, Glass Wool 990 µL
Split – Fast
Injection
No
19251-60540
Empty Pin & Cup
800 µL
Split – Manual
Only
No
18740-80190
Packed Pin & Cup
800 µL
Split – Manual
Only
No
18740-60840
Advanced User Guide
8
Inlets
Splitless liner
The liner volume must contain the solvent vapor. The liner
should be deactivated to minimize sample breakdown during
the purge delay. Solvent vapor volume can be reduced by using
Pulsed Splitless mode. Use the “Vapor Volume Calculator“ to
determine vapor volume requirements.
Vapor volume < 300 µL Use 2 mm liner (250 µL volume),
5181- 8818 or similar.
Vapor volume 225 – 300 µL
reduce vapor volume.
Vapor volume > 300 µL
Consider pulsed splitless mode to
Use 4 mm liner, 5062- 3587 or similar.
Vapor volume > 800 µL Consider pulsed splitless mode to
reduce vapor volume.
For thermally labile or reactive samples, use G1544- 80700
(open top) or G1544- 80730 (top taper) liners.
Table 30
Splitless mode liners
Liner
Advanced User Guide
Description
Volume
Mode
Deactivated Part Number
Single Taper Glass
Wool
900 uL
Splitless
Yes
5062-3587
Single Taper
900 uL
Splitless
Yes
5181-3316
Dual Taper
800 uL
Splitless
Yes
5181-3315
2 mm Quartz
250 uL
Splitless
No
18740-80220
2 mm Quartz
250 uL
Splitless
Yes
5181-8818
1.5 mm
140 uL
No
Direct
Inject, Purge
and Trap,
Headspace
18740-80200
Single Taper Glass
Wool
900 uL
Splitless
Yes
5062-3587
Single Taper
900 uL
Splitless
Yes
5181-3316
4 mm Single Taper
Direct column connect
Yes
G1544-80730
4 mm Dual Taper
Direct column connect
Yes
G1544-80700
181
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Inlets
Vapor Volume Calculator
Agilent provides a Vapor Volume Calculator to help you
determine if a liner is suitable for a method. To use the
calculator install the Agilent Instrument utility provided with
the GC. The calculator is also provided with the Agilent
G4600AA Lab Advisor software.
Setting parameters for the S/SL split mode
Mode
The current operating mode—split
Temperature
Pressure
Actual and setpoint inlet temperatures
Actual and setpoint inlet pressure
Split ratio The ratio of split vent flow to column flow. Column
flow is set at the Column parameter list. This line appears only
if your columns in the flow path are defined.
Split flow Flow, in mL/min, from the split vent. This line
appears only if your columns in the flow path are defined.
Total flow This is the total flow into the inlet, which is the sum
of the split vent flow, column flow, and septum purge flow. When you
change the total flow, the split ratio and split vent flow change while
the column flow and pressure remain the same.
Septum Purge Flow, in mL/min, through the septum purge line.
Recommended range is 1 to 5 mL/min.
If all columns in the flow path are defined
1 Press [Front Inlet] or [Back Inlet].
182
2
Scroll to Mode: and press [Mode/Type]. Select Split.
3
Set the inlet temperature.
4
If you want a specific split ratio, scroll to Split ratio and enter
that number. Split flow will be calculated for you.
5
If you want a specific split flow, scroll to Split flow and enter
that number. Split ratio will be calculated for you.
6
If desired, turn on Gas saver. Set Saver time after the injection
time. Press [Prep Run] (see “Pre Run and Prep Run” on
page 171) before manually injecting the sample.
Advanced User Guide
8
Inlets
If a column in the flow path is not defined
1 Press [Front Inlet] or [Back Inlet].
2
Set the inlet temperature.
3
Set Total flow into the inlet. It must exceed your intended
Septum Purge flow. Measure the split vent flow using a flow
meter.
4
Subtract split vent flow and septum purge flow (see “Pre
Run and Prep Run” on page 171) from Total flow to get
column flow.
5
Calculate the split ratio (split vent flow/column flow). Adjust
as needed.
Selecting parameters for the S/SL splitless mode
A successful splitless injection consists of these steps:
1 Vaporize the sample and solvent in a heated inlet.
2
Use a low flow and low oven temperature to create a
solvent- saturated zone at the head of the column.
3
Use this zone to trap and reconcentrate the sample at the
head of the column.
4
Wait until all, or at least most, of the sample has transferred
to the column. Then discard the remaining vapor in the
inlet—which is mostly solvent—by opening a purge valve. This
eliminates the long solvent tail that this vapor would
otherwise cause.
5
Raise the oven temperature to release the solvent and then
the sample from the head of the column.
Some experimentation is needed to refine the operating
conditions. Table 31 provides starting values for the critical
parameters.
Table 31
Advanced User Guide
Splitless mode inlet parameters
Parameter
Allowed setpoint range
Suggested starting
value
Oven temperature
No cryo, 24 °C to 450 °C
10 °C below solvent
CO2 cryo, –60 °C to 450 °C boiling point
N2 cryo, –80 °C to 450 °C
Oven initial time
0 to 999.9 minutes
≥ Inlet purge time
Inlet purge time
0 to 999.9 minutes
2 x Liner volume
Column flow
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Inlets
Table 31
Splitless mode inlet parameters
Parameter
Allowed setpoint range
Suggested starting
value
Gas saver time
0 to 999.9 minutes
After purge time
Gas saver flow
15 to 1000 mL/min
15 mL/min greater than
maximum column flow
Setting parameters for the S/SL splitless mode
Mode
The current operating mode—splitless
Oven temperature
Temperature
Pressure
Below solvent boiling point
Actual and setpoint inlet temperatures
Actual and setpoint inlet pressure in psi, bar, or kPa
Purge time The time, after the beginning of the run, when you
want the purge valve to open. This is the time in which the
vaporized sample transfers from the liner to the column.
Purge flow The flow, in mL/min, from the purge vent, at Purge
time. You will not be able to specify this value if any column in
the flow path is not defined.
Total flow
The actual flow to the inlet during a Pre- run
(Pre- run light is on and not blinking) and during a run before
purge time. You cannot enter a setpoint at these times. At all
other times, Total flow will have both setpoint and actual values.
Septum Purge
Flow, in mL/min, through the septum purge line.
Septum Purge Flow Mode Standard (septum purge flow is On at
all times) or Switched (septum purge flow is Off during
injection, turns On at Purge time).
If all columns in the flow path are defined
1 Press [Front Inlet] or [Back Inlet].
184
2
Scroll to Mode: and press [Mode/Type]. Select Splitless.
3
Set the inlet temperature.
4
Enter a Purge time and a Purge flow.
5
If desired, turn on Gas saver. Make certain the time is set
after the Purge time.
Advanced User Guide
8
Inlets
6
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample (this is automatic for
Agilent ALS).
If a column in the flow path is not defined
1 Press [Front Inlet] or [Back Inlet].
2
Scroll to Mode: and press [Mode/Type]. Select Splitless.
3
Set the inlet temperature.
4
Enter a Purge time.
5
Set your Total flow greater than the sum of column flow plus
the septum purge flow—see “Pre Run and Prep Run” on
page 171—to guarantee adequate column flow.
6
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample.
Setting parameters for the S/SL pulsed modes
The pulsed mode parameters are the same as the non- pulsed
parameters, but with two additional values.
Pulsed pressure The inlet pressure you want at the start of the
run. The pressure rises to this value when [Prep Run] is pressed
and remains constant until Pulse time elapses, when it returns to
Pressure.
Pulse time This is the time after the start of the run when the
inlet pressure returns to Pressure.
Advanced User Guide
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Inlets
About the Multimode Inlet
The Agilent Multimode (MMI) Inlet System has five operating
modes:
• The split mode is generally used for major component
analyses.
• The pulsed split mode is like the split mode, but with a
pressure pulse applied to the inlet during sample
introduction to speed the transfer of material to the column.
• The splitless mode is used for trace analyses.
• The pulsed splitless mode allows for a pressure pulse during
sample introduction.
• The solvent vent mode is used for large volume injection.
Either single or multiple injections can be made for each run.
• The direct mode allows for a direct forward pressure of
carrier gas through the column. Both the split vent valve and
the septum purge valve are closed.
The MMI can be used with both manual and automatic injection.
Automatic multiple injections (large volume injections) is not
available under GC control alone. See “MMI solvent vent mode”
on page 201.
Septum tightening (MMI)
Septum retainer nuts must be tightened enough to obtain a good
gas seal, but not so much as to compress the septum and make it
difficult to push a syringe needle through it.
For the standard septum retainer nut, an internal spring in the
septum retainer applies pressure to the septum. For inlet
pressures up to 100 psi, tighten the retainer until the C- ring
lifts about 1 mm above the top surface. This is adequate for
most situations.
1 mm
With higher inlet pressures, tighten the septum retainer until
the C- ring stops turning, indicating that the retainer is in firm
contact with the septum.
186
Advanced User Guide
8
Inlets
If using a Merlin Microseal™ septum, finger tighten the septum
nut, until snug (not loose). The pressure capacity depends on
the duckbill seal used.
Heating the MMI
Programming the MMI temperature is similar to programming
the column oven. Access the inlet parameters by pressing [Front
Inlet] or [Back Inlet]. Temperature can be programmed with an
initial temperature and up to 10 ramps (rates and plateaus). See
“MMI split and pulsed split modes” on page 191 for details.
At the end of the run and during post- run, the MMI is held at its
final temperature. This permits backflushing without
contaminating the inlet.
Additional temperature ramps
For most purposes, the MMI is designed to hold the sample in
the inlet liner until the entire sample—there could be several
injections—has been injected. Then the MMI is heated rapidly to
transfer the sample to the column. This can be accomplished
with an initial hold, a single ramp, and a hold at the end to
complete sample transfer.
Additional ramps are available and have several possible uses:
• The inlet can be heated to a high temperature to thermally
clean the liner for the next run.
• The inlet can be programmed downward—just set the Final
temp below the previous temperature—to reduce thermal
stress on the inlet.
• Downward programming can be used to prepare the inlet for
the next run. This can reduce cycle time for greater sample
throughput.
Cooling the MMI
If using cryogen to cool the MMI inlet, both liquid carbon
dioxide (LCO2) and liquid nitrogen (LN2) are supported. In
addition to the cryogenic coolants, the MMI supports
compressed air cooling on both the LCO2 and LN2 cooling
options for legacy applications.
If using cryo as the coolant when configuring the initial inlet
setpoint, set the Use cryo temperature equal to or higher than the
inlet setpoint to cool the inlet and hold the setpoint until the
Advanced User Guide
187
8
Inlets
inlet temperature program exceeds the Use cryo temperature. If
the Use cryo temperature is less than the inlet setpoint, cryogen
will cool the inlet to the initial setpoint and turn off.
If using compressed air as the coolant when configuring the
initial inlet setpoint, Use cryo temperature behaves differently
when in Compressed air mode than it does when in N2 cryo or CO2
cryo mode. In Compressed air mode, the air coolant is used to cool
the inlet regardless of the Use cryo temperature setpoint during
the cooling cycle. If the inlet reaches setpoint, the air coolant is
turned off and stays off. If the oven temperature is high enough
or the inlet was very hot previously, it is possible that the inlet
temperature will rise and the GC will go not ready. For this
reason, it is better to set the instrument cooling configuration
as N2 cryo or CO2 cryo when using compressed air as the coolant.
When using compressed air, the LN2 hardware cools the inlet
faster than the LCO2 hardware. Never use LCO2 or LN2 when
the instrument is configured in Compressed air mode.
If cryo is turned on, and if the inlet is cooled during a run,
cryogen is used to achieve the setpoint. This may have a
negative impact on the chromatographic performance of the
oven and cause distorted peaks.
When a method ends, the cooling setpoint returns to the initial
state of the method, unless you load another method. To
conserve coolant when the GC is idle, load a method that does
not use a cooling configuration.
See “To configure the MMI coolant” on page 31.
MMI split mode minimum operating pressures
The minimum recommended inlet total flow is 20 mL/minute.
When the inlet is operated in a Split mode, there will be a
minimum pressure at which the inlet can operate. Typically, low
inlet pressures may be required for shorter, wide bore columns.
The minimum pressure is a function of carrier gas type, total
inlet flow, liner design, and possible contamination of the split
vent tube or trap.
A wide bore column requires a much lower inlet pressure than a
typical capillary column to maintain a given flow. Setting the
split ratio (total flow) too high when using a wide bore column
can create an unstable control relationship between the
pressure and flow control loops.
188
Advanced User Guide
8
Inlets
Table 32
Approximate minimum viable inlet pressures for MMI in split mode, in psi (kPa)
Split vent flow (mL/min)
50–100
100–200
200–400
400–600
Split liners - 5183-4647, 19251-60540
2.5 (17.2)
3.5 (24.1
4.5 (31)
6.0 (41.4)
Splitless liners - 5062-3587, 5181-8818
4.0 (27.6)
5.5 (37.9)
8.0 (55.2)
11.0 (75.4)
Split liners - 19251-60540, 5183-4647
3.0 (20.7)
4.0(27.6)
—
—
Splitless liners - 5062-3587, 5181-8818
4.0 (27.6)
6.0 (41.4)
—
—
Helium and hydrogen carrier gases
Nitrogen carrier gas
These numbers are based on the resistance to flow of new, clean
inlet systems. Sample condensation in the split vent tube or a
dirty filter can make these values non- attainable.
Selecting the correct MMI liner
Split liner
A good liner for split mode operation will offer very little
restriction to the split flow path between the bottom of the liner
and the inlet body and between the outside of the liner and the
inside of the inlet body. The preferred Agilent split liner, part
number 5183- 4647, incorporates a glass positioning bead on the
bottom to facilitate this. It will also incorporate glass wool or
some other source of surface area inside the liner that provides
for complete sample vaporization across the boiling point range
of the sample. Select an appropriate liner from Table 33.
Table 33
Split mode liners
Liner
Advanced User Guide
Description
Volume
Mode
Deactivated
Part Number
Low Pressure Drop
– Positioning Bead
870 µL
Split – Fast
Injection
Yes
5183-4647
4mm ID, Glass Wool 990 µL
Split – Fast
Injection
No
19251-60540
Empty Pin & Cup
800 µL
Split – Manual
Only
No
18740-80190
Packed Pin & Cup
800 µL
Split – Manual
Only
No
18740-60840
189
8
Inlets
Splitless liner
The liner volume must contain the solvent vapor. The liner
should be deactivated to minimize sample breakdown during
the purge delay. Solvent vapor volume can be reduced by using
Pulsed Splitless mode. Use the “Vapor Volume Calculator“ to
determine vapor volume requirements.
Vapor volume < 300 µL Use 2 mm liner (250 µL volume),
5181- 8818 or similar.
Vapor volume 225 – 300 µL
reduce vapor volume.
Vapor volume > 300 µL
Consider pulsed splitless mode to
Use 4 mm liner, 5062- 3587 or similar.
Vapor volume > 800 µL Consider pulsed splitless mode to
reduce vapor volume.
For thermally labile or reactive samples, use G1544- 80700
(open top) or G1544- 80730 (top taper) liners.
Table 34
Liner
190
Splitless mode liners
Description
Volume
Mode
Deactivated Part Number
Single Taper Glass
Wool
900 uL
Splitless
Yes
5062-3587
Single Taper
900 uL
Splitless
Yes
5181-3316
Dual Taper
800 uL
Splitless
Yes
5181-3315
2 mm Quartz
250 uL
Splitless
No
18740-80220
2 mm Quartz
250 uL
Splitless
Yes
5181-8818
1.5 mm
140 uL
No
Direct
Inject, Purge
and Trap,
Headspace
18740-80200
Single Taper Glass
Wool
900 uL
Splitless
Yes
5062-3587
Single Taper
900 uL
Splitless
Yes
5181-3316
4 mm Single Taper
Direct column connect
Yes
G1544-80730
4 mm Dual Taper
Direct column connect
Yes
G1544-80700
Advanced User Guide
8
Inlets
Vapor Volume Calculator
Agilent provides a Vapor Volume Calculator to help you
determine if a liner is suitable for a method. To use the
calculator install the Agilent Instrument utility provided with
the GC. The calculator is also provided with the Agilent
G4600AA Lab Advisor software.
MMI split and pulsed split modes
The two split modes—with or without a pressure pulse—divide
the gas stream entering the inlet between the column flow and
the split vent flow through the solenoid valve. The ratio of the
split vent flow to the column flow is called the split ratio.
The next figure shows the flows with split and pulsed split
modes.
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
MMI Weldment
FS = Flow Sensor
Advanced User Guide
C
191
8
Inlets
Cold split introduction
For cold split sample introduction, use an initial inlet
temperature below the normal boiling point of the solvent. If the
liner volume is enough to hold all the vaporized solvent, start
the first inlet temperature ramp at 0.1 minutes with a high
heating rate (500 °C/min or higher). The final temperature
should be high enough to volatilize the heaviest analytes from
the liner and should be held for at least 5 minutes. A final
temperature of 350 °C for 5 minutes has proven sufficient to
quantitatively transfer C44.
For larger injection volumes or to eliminate the solvent, hold the
initial temperature long enough to vent the solvent through the
split vent and then begin the first ramp. Use a fast rate for
thermally stable analytes. Slower rates may help minimize
thermal degradation in the inlet.
A single temperature ramp is enough for the injection process.
The remaining ramps may be used to clean the liner or to
reduce the inlet temperature in preparation for the next
injection.
Hot split introduction
For hot split introduction, set an initial temperature high
enough to volatilize the analytes. No additional thermal
parameters are required as the inlet will maintain the setpoint
throughout the run.
Setting parameters for split mode operation
Mode:
The current operating mode—split or pulsed split
Temperature
Actual and setpoint inlet temperatures.
Initial temperature
Initial time
Rate #
Starting temperature for the inlet.
Hold time at the inlet initial temperature.
Temperature program rates for inlet thermal ramps.
Final temp #
Final inlet temperature for ramp 1- 10.
Final time #
Hold time at Final temp 1- 10.
Pressure Actual and setpoint inlet pressure. Controls capillary
column flow and linear velocity.
192
Advanced User Guide
8
Inlets
Split ratio The ratio of split flow to column flow. Column flow
is set in the column parameter list. This line does not appear if a
column in the flow path is not defined.
Split flow Flow, in mL/min, from the split/purge vent. This line
does not appear if a column in the flow path is not defined.
Total flow These are the actual and setpoint values of the total
flow into the inlet, which is the sum of the split flow, column flow,
and septum purge flow. When you change the total flow, the split ratio
and split flow change while the column flow and pressure remain the
same.
Septum Purge
Gas saver
Flow through the septum purge vent.
On to reduce split vent flow at Saver time.
Saver flow
Reduced split vent flow, at least 15 mL/min.
Saver time
Time when flow is reduced to save gas.
If all columns in the flow path are defined
1 Press [Front Inlet].
Advanced User Guide
2
Scroll to Mode: and press [Mode/Type]. Select Split or Pulsed
split.
3
Set the inlet temperature (Initial temperature) and any desired
ramps.
4
If you want a specific split ratio, scroll to Split ratio and enter
that number. The split flow will be calculated and set for you.
5
If you want a specific split flow, scroll to Split flow and enter
that number. The split ratio will be calculated and displayed
for you.
6
If you selected Pulsed split, enter values for Pulsed pressure
(pressure at injection) and Pulse time (minutes after injection
to return to normal pressure).
7
If desired, turn on Gas saver. Set the Saver time after the
injection time.
8
Press [Prep Run] before manually injecting the sample if the
Gas Saver is on (see “Pre Run and Prep Run” on page 171 for
details.).
193
8
Inlets
If a column in the flow path is not defined
1 Press [Front Inlet].
2
Set the inlet temperature (Initial temperature) and any desired
ramps.
3
Set other parameters as described for a defined column.
4
Set Total flow into the inlet. Measure flows out of the split
vent and septum purge vent using a flow meter.
5
Subtract the septum purge flow and split vent flow from Total
flow to get column flow.
6
Calculate the split ratio (split vent flow/column flow). Adjust
as needed
MMI splitless and pulsed splitless modes
In these modes—with or without a pressure pulse—the split vent
valve is closed during injection and vaporization of the sample
and stays so while the sample transfers to the column.
At a specified time after injection, the valve opens to sweep
vapors left in the liner out the split vent. This avoids solvent
tailing due to the large inlet volume and small column flow rate.
Stage 1. Sample injection
With the split vent valve closed, the sample and solvent transfer
to the column.
194
Advanced User Guide
Inlets
Carrier Supply
80 PSI
8
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
MMI Weldment
FS = Flow Sensor
PS = Pressure Sensor
Advanced User Guide
Column
195
8
Inlets
Stage 2. Solvent purging
After the sample has transferred to the column, the split vent
valve opens to purge remaining solvent vapor from the inlet.
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
MMI Weldment
FS = Flow Sensor
PS = Pressure Sensor
196
Column
Advanced User Guide
Inlets
8
Timelines
This figure summarizes the flow, pressure, and temperature
changes during a splitless mode analysis.
Split vent flow
Purge flow
Saver flow
Inlet is
pressure
controlled
Inlet pressure
Prep
Run
Start
Run
Purge
Time
Saver
Time
Stop
Run
Post
Time
Post pressure
Column mode = Constant flow
Inlet pressure
Inlet
temperature
Prep
Run
Start
Run
Purge
Time
Stop
Run
Post
Time
Final temp 1
Initial
temperature
Prep
Run
Advanced User Guide
Start
Run
Purge
Time
197
8
Inlets
Cold splitless introduction
For cold splitless introduction, use an initial inlet temperature
below the normal boiling point of the solvent. For most solvents,
starting the first inlet temperature ramp at 0.1 minutes
provides good transfer and reproducibility. A program rate of
500 °C/min or higher is appropriate for thermally stable
analytes. A final temperature of 350 °C, held for 5 minutes, has
quantitatively transferred up to C44 alkane.
A main advantage of temperature programmability is that the
inlet can be heated gently to transfer delicate analytes. If the
oven temperature is initially low enough to refocus the analytes
on the column, the inlet heating rate can be made slower (e.g.,
120 °C/min). This reduces thermal degradation from the inlet
and can improve peak shape and quantitation.
For most applications of cold splitless, a single temperature
ramp is enough. The remaining ramps can be used to clean the
liner or to decrease the inlet temperature to prepare for the
next injection.
Hot splitless introduction
For hot splitless introduction, select an initial temperature high
enough to volatilize the analytes. No additional temperature
parameters are required as the inlet will maintain the setpoint
throughout the run.
Starting values
A successful splitless injection consists of these steps:
1 Inject the sample and temperature program the inlet to
vaporize it.
2
Use a low column flow and low oven temperature to create a
solvent- saturated zone at the head of the column.
3
Use this zone to trap and reconcentrate the sample at the
head of the column.
4
Wait until all, or at least most, of the sample has transferred
to the column. Then discard the remaining vapor in the
inlet—which is mostly solvent—by opening a purge valve. This
eliminates the long solvent tail that this vapor would
otherwise cause.
5
Raise the oven temperature to analyze the sample.
Some experimentation is needed to refine the operating
conditions. Table 35 provides starting values for the critical
parameters.
198
Advanced User Guide
8
Inlets
Table 35
Splitless mode inlet parameters
Parameter
Allowed setpoint range
Suggested starting
value
Oven temperature
No cryo, ambient+4 °C to 450 °C
CO2 cryo, –40 °C to 450 °C
N2 cryo, –80 °C to 450 °C
10 °C below solvent
boiling point
Oven initial time
0 to 999.9 minutes
≥ Inlet purge time
Inlet purge time
0 to 200.0 minutes
2 x Liner volume
Column flow
Gas saver time
0 to 999.9 minutes
After purge time
Gas saver flow
15 to 200 mL/min
15 mL/min greater
than maximum column
flow
Inlet temperature
No cryo, oven temp + 10 °C
CO2 cryo, –70 °C to 450 °C
N2 cryo, –160 °C to 450 °C
10 °C below solvent
boiling point for 0.1min,
then ramp up
Setting parameters for the splitless modes
Mode: The current operating mode—Splitless or Pulsed
splitless.
Temperature
Initial time
Rate #
Actual and setpoint inlet temperatures.
Hold time at the initial inlet temperature.
Temperature program rates for inlet thermal ramps.
Final temp #
Final inlet temperature for ramp 1- 10.
Final time #
Hold time at Final temp 1- 10.
Pressure
Actual and setpoint inlet pressure in psi, bar, or kPa
Pulsed pres The inlet pressure you desire at the beginning of a
run. The pressure rises to this setpoint after [Prep Run] is
pressed and remains constant until Pulse time elapses, when it
returns to Pressure.
Pulse time
Pressure returns to its normal setpoint at this time.
Purge time The time, after the beginning of the run, when you
want the split vent valve to open.
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Inlets
Purge flow The flow, in mL/min, from the split vent, at Purge
time. You will not be able to specify this value if operating with
your column not defined.
Total flow The Total flow line displays the actual flow to the
inlet during a Pre- run (Pre- run light is on and not blinking) and
during a run before purge time. You cannot enter a setpoint at these
times. At all other times, Total flow will have both setpoint and
actual values.
Septum purge
Gas saver
Flow through the septum purge vent
On to reduce split vent flow at Saver time
Server flow
Reduced split vent flow, at least 15 mL/min
Server time
Time when flow is reduced to save gas
If the column is defined
1 Press [Front Inlet].
2
Scroll to Mode: and press [Mode/Type]. Select Splitless or
Pulsed splitless.
3
Set the inlet temperature and any desired ramps.
4
Enter a Purge time and a Purge flow.
5
If desired, turn Gas saver on. Make certain the time is set
after the Purge time.
6
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample. This is automatic if an
Agilent sampler is used.
If the column is not defined
1 Press [Front Inlet].
200
2
Scroll to Mode: and press [Mode/Type]. Select Splitless or
Pulsed splitless.
3
Set the inlet temperature and any desired ramps.
4
Enter a Purge flow.
5
Enter the Purge time when you wish the split valve to open.
6
Set Total flow greater than the column flow plus the septum
purge flow to guarantee adequate column flow.
7
Turn Gas saver on, if desired. Set the time after Purge time.
Advanced User Guide
8
Inlets
8
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample. This is automatic if an
Agilent sampler is used.
MMI solvent vent mode
This mode is typically used for large volume injections. For
single injection use a 50 to 500 µL syringe and the ALS variable
plunger speed to slowly inject the sample.
The sample is injected into a cold inlet. If conditions are
properly chosen and the sample is suitable, analytes deposit in
the inlet liner while the solvent evaporates and is swept out.
Large or multiple injections can be used to concentrate sample
in the inlet before transferring to the column for analysis.
Stage 1. Sample and vent
During sampling and venting, the split valve is open. The inlet is
at Initial temperature, which is at or below the solvent boiling
point.
Solvent vapors are swept out the vent, while sample deposits on
the liner walls or packing.
Advanced User Guide
201
8
Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
MMI Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Stage 2.
Sample transfer
When solvent venting ends, the split valve vent closes and the
inlet heats to Final temperature 1. The sample transfers to the
capillary column during Purge time. (Purge flow to split vent in a
data system).
202
Advanced User Guide
Inlets
Carrier Supply
80 PSI
8
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
MMI Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Stage 3. Purge and cleanup
The split valve opens again and the system returns to the Stage
1 configuration but with different setpoints. The MMI is flushed.
Additional ramp rates are available to thermally clean the inlet
or to reduce inlet temperature after sample transfer. This can
extend the life of the liner.
Temperature, pressure, and flow considerations
The solvent vent mode goes through three distinct pneumatic
states; venting, sample transfer, and purging. The vent portion
allows the inlet pressure and the vent flow to be adjusted to
optimize solvent elimination. The transfer state mimics
traditional splitless operation and transports the analytes from
the liner to the column. The purging mode allows the user to
prepare the inlet for the next run.
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Inlets
A fundamental difficulty with solvent vent mode is the potential
loss of volatile analytes with the solvent. Several solutions are
possible for this situation:
• The inlet liner can be packed with a more retentive material,
such as Tenax. This greatly improves volatile analyte
recovery but may impact recovery of higher boiling materials.
• Some of the solvent can be left in the liner when sample
transfer begins. The residual solvent acts like a stationary
phase and retains volatile material, but at the expense of a
larger solvent peak.
• The inlet temperature can be reduced. This reduces the
vapor pressure of the volatile analytes and permits higher
recoveries.
Solvent removal can be speeded up by:
• Reducing pressure in the inlet during sample
introduction—the Vent pressure parameter
• Increasing flow through the inlet—the Vent flow parameter
While all these possibilities do complicate use of the PTV, they
provide increased flexibility and new potential to solve difficult
problems.
Sequence of operations
These are the steps in a typical analysis using the solvent vent
mode:
Table 36
The solvent vent process
Step
1
Before injection
Parameter
Value
Flow at split vent
Either Purge flow or Saver flow
Inlet pressure
Derived from column setpoint
The system is resting, with Purge flow (or Saver flow, if on) through the inlet.
2
Prep Run begins
Flow at split vent
Vent flow setpoint
Inlet pressure
Vent pressure setpoint
Setpoints change to prepare for injection. When GC is ready, the sample is injected. Inlet and oven
temperature program Init times begin. Solvent venting and analyte trapping begin.
3
At Vent end time
Flow at split vent
None, split valve closed
Inlet pressure
Column pressure setpoint
Solvent venting ends, analyte transfer begins as inlet heats up.
4
204
At Purge time
Flow at split vent
Purge flow setpoint
Advanced User Guide
8
Inlets
Table 36
The solvent vent process (continued)
Step
Parameter
Value
Inlet pressure
Column pressure setpoint
Analyte transfer ends, inlet is purged of residual vapor. Analysis begins.
5
At Saver time
Flow at split vent
Saver flow setpoint
Inlet pressure
Column pressure setpoint
Analysis ends, carrier flow reduced to save gas (if Saver is on).
Some important points
• The flow through the column is governed by the pressure in
the inlet. This is controlled, during the analysis part of the
process, by the flow or pressure setpoint or program entered
for the column.
• The controlling times must be in the order shown; Vent end
time before Purge time, and Purge time before Saver time.
• Vent end time must occur before the inlet starts to heat and
release analytes.
• Purge time must occur before the oven begins to heat and
move sample through the column.
Timelines
Time increases downward; all other quantities increase to the
right.
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Inlets
Time
Oven temperature
Inlet temperature
Inlet pressure
Split vent flow
Controlled by column
flow or pressure setpoint
or program
Between runs
Prep Run
Start Run
Vent pressure
Saver or
Purge flow
Vent flow
Initial time
Vent end time
Rate 1
Inlet is
pressure
controlled
Initial time
Final temperature 1
Final time 1
Purge time
Rate 1
Other rates,
temperatures,
and times, if
desired
Controlled by
column flow or
pressure setpoint
or program
Purge flow
Final temperature 1
Final time 1
Saver time
Other rates,
temperatures,
and times, if
desired
Saver flow,
if on
When is Start Run?
Both the inlet and oven temperature programs begin at Start
Run. All times—such as Purge time—are measured from Start
Run. When does Start Run occur?
• If the sample is injected manually, Start Run occurs when the
user presses the [Start] key.
• If a single injection per run is made using an autosampler,
Start Run occurs when the syringe carrier moves down to
make the injection.
• If multiple injections per run are made using an autosampler,
Start Run occurs when the syringe carrier moves down to
make the first injection of the set. There are no Start Run
signals for the rest of the injections in the set.
These additional injections take time. The inlet and oven
temperature programs, mainly the Initial time values, must be
adjusted to allow for this. So must the various time values that
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8
Inlets
control the inlet operation. This is discussed in more detail
under “To develop a MMI method that uses large volume
injection” on page 210.
Setting parameters for solvent vent operation
Mode:
The current operating mode—solvent vent.
Temperature
Actual and setpoint initial inlet temperatures.
Initial time The time, measured from Start Run, when the
initial inlet temperature hold ends. Must be greater than Vent
end time.
Rate #
Temperature program rate for inlet thermal ramps.
Final temperature #
Final inlet temperature for ramp 1- 10.
Final time # Hold time at Final temp #. This time is a duration; it
is not measured from Start Run.
Pressure Actual and setpoint inlet pressure before and after
the vent period. It sets the starting point of column head
pressure.
Vent pressure The inlet pressure during the vent period. By
decreasing the inlet pressure while venting, solvent elimination
proceeds faster. Also, the pressure reduction decreases the
amount of carrier gas—and solvent vapor—that enters the
column during this time.
Users select from 0 to 100 psig. If 0 is chosen, the inlet uses the
lowest pressure possible at the given vent flow. Table 37 shows
approximate values for this minimum at various vent flows of
helium. Pressures less than those in the table are not possible
unless the flow is reduced.
Table 37
Advanced User Guide
Minimum attainable pressures
Vent flow (mL/min)
Actual vent pressure at
“0“ psig setpoint
Actual vent pressure at
“0” kPa setpoint
50
0.7
5
100
1.3
10
200
2.6
18
500
6.4
44
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Inlets
Table 37
Minimum attainable pressures
Vent flow (mL/min)
Actual vent pressure at
“0“ psig setpoint
Actual vent pressure at
“0” kPa setpoint
1000
12.7
88
Vent flow The flow of carrier gas out the split vent during the
vent period. Higher flows sweep the liner more quickly and
reduce the time for solvent elimination. For most columns,
100 mL/min vent flow eliminates solvent at an acceptable rate
but puts minimal material on the column.
Vent end time The time, measured from Start Run, when
solvent venting ends. For large volume injections, this time is
normally greater than the time for the injection to complete.
Purge time The time, measured from Start Run, when sample
transfer ends. It began at Vent end time.
Purge flow The flow of carrier gas to the inlet beginning at
Purge time.
Total flow
The actual flow into the inlet.
Septum Purge
Gas saver
Flow through the septum purge vent
On to reduce split vent flow at Saver time
Saver flow
Reduced split vent flow, at least 15 mL/min
Saver time
Time when flow is reduced to save gas
If the column is defined
1 Press [Front Inlet].
208
2
Scroll to Mode: and press [Mode/Type]. Select Solvent vent.
3
Enter a Vent pressure, a Vent flow, and a Vent end time.
4
Set the inlet temperature and ramps, as desired.
5
Enter a Purge time and a Purge flow.
6
If desired, turn Gas saver on. Make certain the time is set
after the Purge time.
7
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample.
Advanced User Guide
8
Inlets
If the column is not defined
1 Set up the parameters as described for the defined column
case.
2
Set Total flow greater than the column flow plus the septum
purge flow to guarantee adequate column flow.
MMI Direct Mode
MMI Direct Mode is a pneumatic configuration that allows
on- column like behavior. In this mode, you still use a liner to
trap involatile material but the sample can only enter the
column.
Direct mode works best with direct connect liners. These liners
form a seal with the column so that the sample cannot leak out
of the liner. The inlet is held at a temperature below the solvent
boiling point, just as in cool on- column (COC) during the
injection. Pneumatically, the inlet is in forward pressure
regulation, similar to the splitless portion of splitless mode. The
inlet is then temperature programmed to transfer any
remaining volatile material to the column.
The only control parameter for Direct Mode is inlet pressure.
You can run the column in any of its normal control modes
(constant pressure, constant flow, ramped pressure, ramped
flow). Gas saver does not work in this mode as there is no purge
state.
The next figure shows the flows with direct mode.
Advanced User Guide
209
8
Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
MMI Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
To develop a MMI method that uses large volume injection
This topic provides a recommended way to change from a
splitless injection using a split/splitless inlet to a solvent vent
mode injection using a Multimode inlet (MMI). It applies mainly
to large volume injections (LVI) using a Multimode inlet, but the
concepts can apply to general MMI use. This topic does not
consider all items that can impact an analysis, for example the
liner, solvent, analyte boiling points, or polarity. This topic also
assumes knowledge of your data system—when to save a
method, how to start a run, how to set up a single run, etc.
The main advantage of the MMI's solvent vent mode is that you
can inject slowly into the inlet, allowing large amounts of
solvent to evaporate in the liner (not in the split vent line),
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Advanced User Guide
8
Inlets
concentrating the analytes prior to injection. This requires an
injector with variable speed injections, a "large" syringe, and
knowledge of the sample and the solvent. When developing a
solvent vent method, the goal for the injection is to determine
the injection rates and temperatures needed to evaporate the
solvent at the rate it enters the inlet. The development
technique is to gradually scale up to an injection amount that
produces a useful response. The most significant parameters
are:
Inlet temperature. Hold the inlet temperature at or slightly
below the solvent boiling point until after all the sample has
been injected. This is important so that you do not boil away
more volatile analytes, or boil away the solvent in the needle
and trap your analytes there. An additional point to consider is
that the boiling point of the earliest eluting analyte should be
100 °C > the boiling point of the solvent.
Injection speed. Estimate the evaporation rate of solvent
exiting the needle based on solvent type, inlet temperature, vent
flow, and pressure. Start with about half that number. Note that
you have to make sure that you configure the syringe properly.
If not, you will over- or under- load the inlet.
Vent time. Make sure the vent time setpoint is greater than the
time the needle spends in the inlet. If the vent time is too short,
you will overload and contaminate the column and inlet.
Change the vent time as you upscale the method.
If using a MMI with an MSD, another tip for method
development is to scan for solvent ions. Detecting the solvent
ions can be useful in troubleshooting residual solvent bleed onto
the column.
To develop a MMI method for large volume injection, try the
following:
1 Determine a small injection volume that works on a
split/splitless inlet in splitless mode. Choose a volume that
does not currently overload the inlet.
Advanced User Guide
2
Start with a 5–10 uL syringe and make sure the syringe is
properly configured in the instrument and data system.
3
Make sure the column is configured.
4
Set up the inlet to perform a 1 uL injection. Use the
split/splitless inlet method conditions, except:
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8
Inlets
• Start with the inlet temperature cold, near but slightly
below the solvent boiling point. For example, if using
methylene chloride (boiling point 39 °C), start with a
temperature of 30–39 °C.
• Use Splitless mode.
• Ramp to the normal split/splitless inlet temperature
5
Note the response achieved.
6
Next, change the inlet mode to Solvent Vent.
7
Check the injector timings.
a Install an empty sample vial in the injector turret or tray.
b Input the injection rate (Draw, Dispense, and Inject rates)
for the injector and increase the injection volume to 5 uL.
c Enter draft Solvent Vent parameters:
• Set a Vent Flow of 100 mL/min as a starting point.
• Keep the inlet isothermal for now
• Enter a Vent Pressure of 0 psi (0 kPa) until 0.1 min.
• Make an injection using the empty vial. Use a
stopwatch or your GC's timer feature to time how long
the needle is in the inlet.
8
Enter revised Solvent Vent mode parameters.
• Set the method's Vent Time to be about 0.05 min longer
than the time the needle spends in the inlet.
• Set the inlet temperature initial Hold Time to be about
0.05 min longer than the vent pressure until time.
• Program the inlet to ramp quickly to the injection
temperature. Make sure the ramp starts after the vent
pressure until time.
• Set the Purge Flow to Split Vent to 30 mL/min. Set the
purge time to be the vent pressure until time + 1 minute.
9
Make a 5 uL injection of your standard. You should see 5
times the response.
If the response of all analytes is too low:
• The dispense speed is too fast. Liquid was injected into
the inlet and pushed out the vent.
• The vent time is too long. The inlet started to heat
while the vent was open.
If the response of early eluters is too low:
• The inlet temperature is too high.
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8
Inlets
• The Vent Flow is too high.
If the response of late eluters is too low:
• The purge time is too short.
• The final inlet temperature is too low.
10 If you need more injection volume and the 5 uL worked to
give 5X response, change the syringe to a larger one, for
example 50 uL.
11 Set up the data system to perform a 25 uL injection.
12 Configure the syringe. Make sure the plunger speeds on the
injector are still set properly.
13 Recheck the injector timings. See step 12.
14 Set a new vent time and initial inlet temperature time based
on the new time the needle spends in the syringe.
15 Make a 25 uL injection of your standard. Again, you should
see 5 times the response. If not, see step 13.
16 If you need more response, repeat steps 10 – 15 to increase
to larger volume. Also try performing 5 x 5 uL injections,
then 5 x 50 uL injections.
Multiple injections with the MMI
The preferred technique for concentrating analytes in the inlet
liner is to use a single, large volume injection. Using a high
capacity syringe and one septum puncture reduces the
possibility of contamination and generally improves results
when compared against a multiple septum puncture technique.
However, if needed, you can perform multiple septum punctures
during the vent time. This technique requires an Agilent data
system and automatic liquid sampler.
Data system requirements
An Agilent data system is necessary for multiple injection
because the needed parameters are not available through the
GC keyboard.
GC ChemStation
MSD ChemStation
EZChrom
Advanced User Guide
Software revision B.04.01 SP1 or later.
Software revision E.02.00 SP2 or later
Software revision 3.3.2 or later
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8
Inlets
Setting parameters for the inlet in solvent vent mode
Set or configure the following parameters in the data system's
7890A GC method editor.
Syringe size — Verify the syringe size is configured correctly.
The configured syringe size changes the available choices for
injection volume.
Injection volume — Select the injection volume, then enter a
number of injections. The total injection volume will be
displayed.
Multiple Injection Delay — A pause time, in seconds, between
injections. This is added to the minimum hardware cycle time.
Preinjection washes and pumps are performed only before the
first injection of a multiple injection set.
Postinjection washes are performed only after the last injection
in a multiple injection set.
An example
These values were used for a sample with a broad range of
boiling points.
Table 38
Name
Value
Sample
C10 to C44 hydrocarbons in hexane
Mode
Solvent vent
MMI liner
Glass wool packed
Injection volume
One 10.0 μL injection (25 μL syringe)
Injection speed
Fast
Column
30 m x 320 μm x 0.25 μm -5, part
number 19091J-413
Column flow
4 mL/min constant flow
Table 39
214
General parameters
Inlet parameters
Name
Value
Name
Value
Initial temp
40 °C
Rate 2 (off)
Initial time
0.3 min
Pressure
15.6 psig
Rate 1
720 °C/min
Vent pressure
0.0 psig
Advanced User Guide
Inlets
Table 39
Inlet parameters
Name
Value
Name
Value
Final temp 1
450 °C
Vent flow
100 mL/min
Final time 1
5 min
Vent end time
0.2 min
Rate 2
100 °C/min
Purge time
2.0 min
Final temp 2
250 °C
Purge flow
50 mL/min
Final time 2
0 min
Table 40
8
Oven parameters
Name
Value
Initial temp
40 °C
Initial time
2.5 min
Rate 1
25 °C/min
Final temp 1
320 °C
Final time 1
10.0 min
Rate 2 (off)
Table 41
Advanced User Guide
Detector parameters
Name
Value
Detector
FID
Detector temp
400 °C
Hydrogen flow
40 mL/min
Air flow
450 mL/min
Makeup (N2)
45 mL/min
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Inlets
C20
These results were compared with a splitless analysis of the
same sample, which should produce 100% recovery of all
analytes. The data showed that, under these conditions,
compounds above C20 were completely recovered and that the
recovery was independent of injection size. Compounds lower than
C20 were partially vented with the solvent.
Possible adjustments
Depending on what you are trying to accomplish, you have a
number of possible adjustments available.
To eliminate more solvent
• Increase the vent end time, inlet initial time, and purge time.
This will not affect analytes that are quantitatively trapped
but will eliminate more of the solvent peak.
• Increase the vent flow to sweep the liner more rapidly with
the same inlet timing. Increasing vent flow raises vent
pressure if it is set to 0. This puts more solvent onto the
column.
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Inlets
8
• Raise the inlet initial temperature to vaporize more solvent
and allow more to be eliminated. This also increases the loss
of volatile analytes since their vapor pressures also increase.
To improve recovery of low boiling analytes
• Reduce inlet temperature to lower the vapor pressure of the
analytes and trap them more effectively. This also reduces
solvent vapor pressure and more time will be needed to
eliminate it.
• Use a retentive packing in the liner. Materials such as Tenax
permit higher recovery of volatile analytes but may not
release higher boiling compounds. This must be considered if
quantitation on these high boiling peaks is desired.
• Leave more solvent in the liner. The solvent acts as a pseudo
stationary phase and helps retain volatile analytes. This
must be balanced against the detector’s tolerance for solvent.
An example—continued
The single injection example shown on the last few pages makes
it clear that a 10 μL injection does not overload the glass wool
packed liner. This means that multiple 10 μL injections are
possible.
It was decided to make 10 injections per run, each of 10 μL size.
This would increase analytical sensitivity substantially. No
adjustments were made to improve recovery of the low boilers
since the purpose of this analysis was to detect and measure the
high boiling components.
After timing a trial set of 10 injections, the total time for the
multiple injection set was measured to be approximately
1.3 minutes. The following timing changes were made:
Table 42
Modifications
Parameter
Increased from
To
Inlet Init time
0.3 minutes
1.6 minutes
Vent end time
0.2 minutes
1.5 minutes
Purge time
2.0 minutes
3.0 minutes
Oven Init time
2.5 minutes
3.0 minutes
The result is shown in the next figure. Note the difference in the
vertical scale (5000 versus 500).
Advanced User Guide
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Inlets
C20
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8
Inlets
About the Packed Column Inlet
This inlet is also known as the purged packed inlet (PP). It is
used with packed columns when high- efficiency separations
are not required. It can also be used with wide- bore capillary
columns, if flows greater than 10 mL/min are acceptable.
If the columns are not defined (packed columns and undefined
capillary columns), the inlet is usually flow- controlled. If
capillary columns are used and the columns in the flow path are
defined, the inlet is normally pressure- controlled but can be
put into the flow control mode.
The figure shows the inlet in the capillary column mode, with
the column defined and the flow controlled by pressure.
Carrier Supply
80 PSI
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
FS
PS
PS
Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Advanced User Guide
Column
219
8
Inlets
The next figure shows the flow diagram for the packed column
mode, with the column not defined the control is based on total
carrier gas flow.
Carrier Supply
80 PSI
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
PS
FS
PS
Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Packed Column
Setting parameters
The inlet can operate in flow or pressure control mode. Flow is
recommended for packed columns. Pressure is recommended
for capillary columns.
Inlet in flow control mode
While in flow control mode, you cannot enter pressures here.
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8
Inlets
Mode Press [Mode/Type] to see the choices. You may select an
inlet mode of either Pressure control or Flow control. When the
Inlet control mode is Pressure control, the column control mode
can be set to Constant pressure, Ramped pressure, Constant flow, or
Ramped flow. The column control mode is set from the Column
parameters display. When the Inlet control mode is Flow
control, only column flow can be set on the Column parameters
display.
Temperature
The setpoint and actual temperature values.
Pressure The actual pressure (in psi, bar, or kPa) supplied to
the inlet. You cannot enter a setpoint here.
Total flow Enter your setpoint here, actual value is displayed.
Inlet is mass flow controlled.
Septum purge The setpoint and actual flow, in mL/min,
through the septum purge line, typically 1 to 5 mL/min
Inlet in pressure control mode
While in pressure control mode, you cannot enter flows here.
Mode Press [Mode/Type] to see the choices. You may select an
inlet mode of either Pressure control or Flow control. When the
Inlet control mode is Pressure control, the column control mode
can be set to Constant pressure, Ramped pressure, Constant flow, or
Ramped flow. The column control mode is set from the Column
parameters display. When the Inlet control mode is Flow
control, only column flow can be set on the Column parameters
display.
Temperature
inlet.
The setpoint and actual temperature values of the
Pressure Enter your setpoint here (in psi, bar, or kPa). The
actual value is displayed.
Total flow The actual total flow to the inlet. This is a reported
value, not a setpoint.
Septum purge The setpoint and actual flow, in mL/min,
through the septum purge line, typically 1 to 5 mL/min
Advanced User Guide
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Inlets
About the Cool On-Column Inlet
This inlet introduces liquid sample directly onto a capillary
column. To do this, both the inlet and the oven must be cool at
injection, either at or below the boiling point of the solvent.
Because the sample does not vaporize immediately in the inlet,
problems with sample discrimination and sample alteration are
minimized. If done properly, cool- on column injection also
provides accurate and precise results.
You can operate the inlet in track oven mode, where the inlet
temperature follows the column oven, or you can program up to
three temperature ramps. A cryogenic cooling option that uses
liquid CO2 or N2 from the oven cryogenic system can reach
sub- ambient temperatures.
Carrier Supply
80 PSI
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
PS
PS
Septum
Cool on Column
Inlet Weldment
Column Adapter
Ferrule
Column Nut
Column
PS = Pressure Sensor
222
Column
Advanced User Guide
8
Inlets
Setup modes of the COC inlet
The COC inlet hardware must be set up for one of three usages,
depending on the type of injection and column size.
• 0.25 mm or 0.32 mm automated on- column. Use predrilled
septa.
• 0.53 mm automatic on- column or retention gap
• 0.2 mm manual
To select the correct hardware for a column and injection type,
refer to Maintaining Your GC.
Retention gaps
Because the sample is injected directly onto the column, it is
strongly suggested that a retention gap—or guard column—be
used to protect your column. A retention gap is a deactivated
column that is connected between the inlet and the analytical
column. If you choose to use one, it is suggested that at least 1 m
of retention gap be installed per 1 μL of sample injected.
Information on ordering retention gaps can be found in the
Agilent catalog for consumables and supplies.
If you are using a retention gap and are operating with the
column defined, the length of the retention gap could affect the
calculations for flow and velocity through your column. If your
retention gap is the same inside diameter as your column, it is a good
idea to add the retention gap and column length before entering the
number on the Configure Column parameter list. If the retention gap
inside diameter is larger than your column, this step may not be
necessary.
COC inlet temperature control
CryoBlast (optional)
CryoBlast shortens the cycle time between runs. If you have a
CO2 or N2 cryogenic valve and the CryoBlast feature, you can cool the
inlet to –37 °C in either the track oven or temperature program
modes.
The CryoBlast accessory uses coolant from the oven cryogenic
system.
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Inlets
Track oven mode
In the Track oven mode, the inlet temperature stays 3 °C higher
than the oven temperature throughout the oven program. You
cannot enter a temperature setpoint—it is set automatically. If
you have CryoBlast, the inlet will track oven temperatures to
–40°C; without CryoBlast, the lower limit is set by room
temperature.
Temperature programming mode
In this mode, you can enter up to three temperature ramps in
the inlet parameter list so that the inlet and the oven operate
independently. This is the recommended mode if operating
below –20 °C.
At these very low oven temperatures, the inlet temperature
should be at least 20 °C higher than the oven temperature. This
will be more than adequate for solvent focusing.
At temperatures greater than ambient, the inlet should always
be at least 3 °C warmer than the oven for proper control of the
inlet temperature.
The oven temperature program controls the run. If it is longer
than the inlet temperature program, the inlet will remain at its
final temperature until the oven program (and the run) ends.
Cryogenic considerations
When using track oven mode with a cryogenic oven, all other
inlets must be off or in track oven mode.
If cryo is turned on, and if the inlet is cooled during a run,
cryogen is used to achieve the setpoint. This may have a
negative impact on the chromatographic performance of the
oven and cause distorted peaks.
The inlet uses the same cryo coolant as configured for the oven.
Setting COC inlet flows/pressures
1 Configure capillary column to inlet—select constant flow or
pressure.
224
2
Set column flow, linear velocity, or inlet pressure.
3
Set Septum Purge, typically 3 to 10 mL/min.
Advanced User Guide
8
Inlets
Setting COC inlet parameters
Track oven mode
1 Press [Front Inlet] or [Back Inlet].
2
Press [Mode/Type] and select Track oven.
There is no setpoint for Track oven mode.
Ramped temperature mode
1 Press [Front Inlet] or [Back Inlet].
Advanced User Guide
2
Press [Mode/Type] and select Ramped temp.
3
Enter a value for Temp. This is the starting temperature.
4
Enter an Init time. This is the length of time the inlet will stay
at the starting temperature after a run has begun.
5
Enter Rate 1. This is the rate at which the inlet will be heated
or cooled. A Rate of 0 halts further programming.
6
Enter Final temp 1. This is the inlet temperature at the end of
the first ramp.
7
Enter Final time 1. This is the number of minutes the inlet
holds Final temp 1.
8
To enter a second (or third) ramp, scroll to the appropriate
Rate line and repeat steps 5 through 7.
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Inlets
About the PTV Inlet
The Agilent Programmed Temperature Vaporization (PTV) Inlet
System has five operating modes:
• The split mode is generally used for major component
analyses.
• The pulsed split mode is like the split mode, but with a
pressure pulse applied to the inlet during sample
introduction to speed the transfer of material to the column.
• The splitless mode is used for trace analyses.
• The pulsed splitless mode allows for a pressure pulse during
sample introduction.
• The solvent vent mode is used for large volume injection.
Either single or multiple injections can be made for each run.
The PTV inlet can be used with both manual and automatic
injection.
For automatic multiple injections (large volume injections), an
Agilent GC or MSD ChemStation is required. This function is
not available under GC control alone. See “PTV inlet solvent
vent mode” on page 239.
PTV sampling heads
Two heads are available for the PTV inlet.
The septum head uses either a regular septum or a Merlin
Microseal™ to seal the syringe passage. A stream of gas sweeps
the inner side of the septum and exits through the septum purge
vent on the pneumatics module. It may be used with either
automatic or manual injection.
The septum head uses either standard 11 mm septa or (with a
different cap) a Merlin Microseal.
The septumless head uses a check valve instead of a septum to
seal the syringe entrance passage. It may be used with either
automatic or manual injection. This head is recommended for
subambient inlet operation.
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Inlets
Septum head
Septumless head
The flow diagrams in the rest of this document show the septum
head in place with a separate drawing for the septumless head.
Heating the PTV inlet
The control parameters for PTV temperature programming are
the same as for the column oven, but are reached by pressing
[Front Inlet]. Temperature can be programmed with an initial
temperature and up to 3 rates and plateaus. Rates between 0.1
and 720 °C/min can be selected. See “Setting COC inlet
parameters” on page 225 for details.
At the end of the run and during post- run, the PTV is held at its
final temperature. This permits backflushing without
contaminating the inlet.
CAUTION
If the initial inlet temperature and the oven initial temperature are
too close, the inlet may be unable to maintain its setpoint. We
recommend a difference of at least 6 °C, either higher or lower.
Additional temperature ramps
For most purposes, the PTV is designed to hold the sample in
the inlet liner until the entire sample—there could be several
injections—has been injected. Then the PTV is heated rapidly to
transfer the sample to the column. This can be accomplished
with an initial hold, a single ramp, and a hold at the end to
complete sample transfer.
Two additional ramps are available and have several possible
uses:
• The inlet can be heated to a high temperature to thermally
clean the liner for the next run.
• The inlet can be programmed downward—just set the Final
temp below the previous temperature—to reduce thermal
stress on the inlet.
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Inlets
• Downward programming can be used to prepare the inlet for
the next run. This can reduce cycle time for greater sample
throughput.
Cooling the PTV inlet
If cryo is turned on, and if the inlet is cooled during a run,
cryogen is used to achieve the setpoint. This may have a
negative impact on the chromatographic performance of the
oven and cause distorted peaks.
The sample may be injected into either a cooled or heated inlet.
The initial inlet temperature can be reduced to –60 °C (with
CO2 cooling) or to –160 °C (with liquid N2 cooling).
The inlet uses the same coolant as configured for the oven.
PTV inlet split and pulsed split modes
The two split modes—with or without a pressure pulse—divide
the gas stream entering the inlet between the column flow, the
split vent flow through the solenoid valve, and the septum purge
flow. The ratio of the split vent flow to the column flow is called
the split ratio.
The next figure shows the flows with the septum head. Flows
with the septumless head are the same except that the septum
purge flow bypasses the head.
228
Advanced User Guide
Inlets
Carrier Supply
80 PSI
Split
8
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
PTV Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Cold split introduction
For cold split sample introduction, use an initial inlet
temperature below the normal boiling point of the solvent. If the
liner volume is enough to hold all the vaporized solvent, start
the first inlet temperature ramp at 0.1 minutes with a high
heating rate (500 °C/min or higher). The final temperature
should be high enough to volatilize the heaviest analytes from
the liner and should be held for at least 5 minutes. A final
temperature of 350 °C for 5 minutes has proven sufficient to
quantitatively transfer C44.
For larger injection volumes or to eliminate the solvent, hold the
initial temperature long enough to vent the solvent through the
split vent and then begin the first ramp. Use a fast rate for
thermally stable analytes. Slower rates may help minimize
thermal degradation in the inlet.
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Inlets
A single temperature ramp is enough for the injection process.
The remaining ramps may be used to clean the liner or to
reduce the inlet temperature in preparation for the next
injection.
Hot split introduction
For hot split introduction, set an initial temperature high
enough to volatilize the analytes. No additional thermal
parameters are required as the inlet will maintain the setpoint
throughout the run.
Because of the small liner volume (about 120 microliters), the
PTV has a limited injection capacity with hot split introduction.
Injection volumes exceeding 1 μL in the hot split mode may
overflow the inlet causing analytical problems. Cold split
introduction avoids this potential problem.
Setting parameters for split mode operation
Mode:
The current operating mode—split or pulsed split
Temperature
Actual and setpoint inlet temperatures.
Initial temperature
Initial time
Rate #
Starting temperature for the inlet.
Hold time at the inlet initial temperature.
Temperature program rates for inlet thermal ramps.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time #
Hold time at Final temp 1, 2, and 3.
Pressure Actual and setpoint inlet pressure. Controls capillary
column flow and linear velocity.
Split ratio The ratio of split flow to column flow. Column flow
is set in the column parameter list. This line does not appear if a
column in the flow path is not defined.
Split flow Flow, in mL/min, from the split/purge vent. This line
does not appear if a column in the flow path is not defined.
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Inlets
Total flow These are the actual and setpoint values of the total
flow into the inlet, which is the sum of the split flow, column flow,
and septum purge flow. When you change the total flow, the split ratio
and split flow change while the column flow and pressure remain the
same.
Septum Purge
Gas saver
Flow through the septum purge vent.
On to reduce split vent flow at Saver time.
Saver flow
Reduced split vent flow, at least 15 mL/min.
Saver time
Time when flow is reduced to save gas.
If all columns in the flow path are defined
1 Press [Front Inlet].
2
Scroll to Mode: and press [Mode/Type]. Select Split or Pulsed
split.
3
Set the inlet temperature (Initial temperature) and any desired
ramps.
4
If you want a specific split ratio, scroll to Split ratio and enter
that number. The split flow will be calculated and set for you.
5
If you want a specific split flow, scroll to Split flow and enter
that number. The split ratio will be calculated and displayed
for you.
6
If you selected Pulsed split, enter values for Pulsed pressure
(pressure at injection) and Pulse time (minutes after injection
to return to normal pressure).
7
If desired, turn on Gas saver. Set the Saver time after the
injection time.
8
Press [Prep Run] before manually injecting the sample if the
Gas Saver is on (see “Pre Run and Prep Run” on page 171).
If a column in the flow path is not defined
1 Press [Front Inlet].
Advanced User Guide
2
Set the inlet temperature (Initial temperature) and any desired
ramps.
3
Set other parameters as described for a defined column.
4
Set Total flow into the inlet. Measure flows out of the split
vent and septum purge vent using a flow meter.
5
Subtract the septum purge flow and split vent flow from Total
flow to get column flow.
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8
Inlets
6
Calculate the split ratio (split vent flow/column flow). Adjust
as needed
PTV inlet splitless and pulsed splitless modes
In these modes—with or without a pressure pulse—the split vent
valve is closed during injection and vaporization of the sample
and stays so while the sample transfers to the column.
At a specified time after injection, the valve opens to sweep
vapors left in the liner out the split vent. This avoids solvent
tailing due to the large inlet volume and small column flow rate.
The figures show the flows with the septum head. Flows with
the septumless head are the same except that the septum purge
flow bypasses the head.
Stage 1. Sample injection
With the split vent valve closed, the sample and solvent transfer
to the column.
232
Advanced User Guide
8
Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
PTV Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Stage 2. Solvent purging
After the sample has transferred to the column, the split vent
valve opens to purge remaining solvent vapor from the inlet.
Advanced User Guide
233
8
Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
PTV Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Timelines
This figure summarizes the flow, pressure, and temperature
changes during a splitless mode analysis.
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Advanced User Guide
Inlets
Split vent flow
Purge flow
Saver flow
Inlet is
pressure
controlled
Inlet pressure
8
Prep
Run
Start
Run
Purge
Time
Saver
Time
Stop
Run
Post
Time
Post pressure
Column mode = Constant flow
Inlet pressure
Inlet
temperature
Prep
Run
Start
Run
Purge
Time
Stop
Run
Post
Time
Final temp 1
Initial temperature
Prep
Run
Start
Run
Purge
Time
Cold splitless introduction
For cold splitless introduction, use an initial inlet temperature
below the normal boiling point of the solvent. For most solvents,
starting the first inlet temperature ramp at 0.1 minutes
provides good transfer and reproducibility. A program rate of
500 °C/min or higher is appropriate for thermally stable
analytes. A final temperature of 350 °C, held for 5 minutes, has
quantitatively transferred up to C44 alkane.
A main advantage of temperature programmability is that the
inlet can be heated gently to transfer delicate analytes. If the
oven temperature is initially low enough to refocus the analytes
on the column, the inlet heating rate can be made slower (e.g.,
120 °C/min). This reduces thermal degradation from the inlet
and can improve peak shape and quantitation.
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Inlets
For most applications of cold splitless, a single temperature
ramp is enough. The remaining ramps can be used to clean the
liner or to decrease the inlet temperature to prepare for the
next injection.
Hot splitless introduction
For hot splitless introduction, select an initial temperature high
enough to volatilize the analytes. No additional temperature
parameters are required as the inlet will maintain the setpoint
throughout the run.
Because of the small liner volume (about 120 μL), the PTV
cannot contain vapor resulting from large liquid injection
volumes. Injection volumes greater than 1 μL may overflow
vapor from the inlet, causing analysis variations. Cold splitless
introduction avoids this problem.
Starting values
A successful splitless injection consists of these steps:
1 Inject the sample and temperature program the inlet to
vaporize it.
2
Use a low column flow and low oven temperature to create a
solvent- saturated zone at the head of the column.
3
Use this zone to trap and reconcentrate the sample at the
head of the column.
4
Wait until all, or at least most, of the sample has transferred
to the column. Then discard the remaining vapor in the
inlet—which is mostly solvent—by opening a purge valve. This
eliminates the long solvent tail that this vapor would
otherwise cause.
5
Raise the oven temperature to analyze the sample.
Some experimentation is needed to refine the operating
conditions. Table 43 provides starting values for the critical
parameters.
Table 43
236
Splitless mode inlet parameters
Parameter
Allowed setpoint range
Suggested starting
value
Oven temperature
No cryo, ambient+10 °C to 450 °C 10 °C below solvent
CO2 cryo, –60 °C to 450 °C
boiling point
N2 cryo, –80 °C to 450 °C
Oven initial time
0 to 999.9 minutes
≥ Inlet purge time
Advanced User Guide
8
Inlets
Table 43
Splitless mode inlet parameters (continued)
Parameter
Allowed setpoint range
Suggested starting
value
Inlet purge time
0 to 999.9 minutes
2 x Liner volume
Column flow
Gas saver time
0 to 999.9 minutes
After purge time
Gas saver flow
15 to 1000 mL/min
15 mL/min greater
than maximum column
flow
Inlet temperature
No cryo, oven temp + 10 °C
CO2 cryo, –50 °C to 450 °C
N2 cryo, –60 °C to 450 °C
10 °C below solvent
boiling point for 0.1min,
then ramp up
Setting parameters for the splitless modes
Mode: The current operating mode—Splitless or Pulsed
splitless.
Temperature
Initial time
Rate #
Actual and setpoint inlet temperatures.
Hold time at the initial inlet temperature.
Temperature program rates for inlet thermal ramps.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time #
Hold time at Final temp 1, 2, and 3.
Pressure
Actual and setpoint inlet pressure in psi, bar, or kPa
Pulsed pres The inlet pressure you desire at the beginning of a
run. The pressure rises to this setpoint after [Prep Run] is
pressed and remains constant until Pulse time elapses, when it
returns to Pressure.
Pulse time
Pressure returns to its normal setpoint at this time.
Purge time The time, after the beginning of the run, when you
want the split vent valve to open.
Purge flow The flow, in mL/min, from the split vent, at Purge
time. You will not be able to specify this value if operating with
your column not defined.
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237
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Inlets
Total flow The Total flow line displays the actual flow to the
inlet during a Pre- run (Pre- run light is on and not blinking) and
during a run before purge time. You cannot enter a setpoint at these
times. At all other times, Total flow will have both setpoint and
actual values.
Septum purge
Gas saver
Flow through the septum purge vent
On to reduce split vent flow at Saver time
Server flow
Reduced split vent flow, at least 15 mL/min
Server time
Time when flow is reduced to save gas
If the column is defined
1 Press [Front Inlet].
2
Scroll to Mode: and press [Mode/Type]. Select Splitless or
Pulsed splitless.
3
Set the inlet temperature and any desired ramps.
4
Enter a Purge time and a Purge flow.
5
If desired, turn Gas saver on. Make certain the time is set
after the Purge time.
6
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample. This is automatic if an
Agilent sampler is used.
If the column is not defined
1 Press [Front Inlet].
238
2
Scroll to Mode: and press [Mode/Type]. Select Splitless or
Pulsed splitless.
3
Set the inlet temperature and any desired ramps.
4
Enter a Purge flow.
5
Enter the Purge time when you wish the split valve to open.
6
Set Total flow greater than the column flow plus the septum
purge flow to guarantee adequate column flow.
7
Turn Gas saver on, if desired. Set the time after Purge time.
8
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample. This is automatic if an
Agilent sampler is used.
Advanced User Guide
8
Inlets
PTV inlet solvent vent mode
This mode is typically used for large volume injections. For
single injection use a 50 or 100 µL syringe with variable plunger
speed—slowly, 5 to 30 seconds.
The sample is injected into a cold inlet. If conditions are
properly chosen and the sample is suitable, analytes deposit in
the inlet liner while the solvent evaporates and is swept out.
Large or multiple injections can be used to concentrate sample
in the inlet before transferring to the column for analysis.
The figure shows the flows with the septum head. Flows with
the septumless head are the same except that the septum purge
flow bypasses the head.
Stage 1. Sample and vent
During sampling and venting, the split valve is open. The inlet is
at Initial temperature, which is at or below the solvent boiling
point.
Solvent vapors are swept out the vent, while sample deposits on
the liner walls or packing.
Advanced User Guide
239
8
Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
PTV Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Stage 2.
Sample transfer
When solvent venting ends, the split valve vent closes and the
inlet heats to Final temperature 1. The sample transfers to the
capillary column during Purge delay time.
240
Advanced User Guide
Inlets
Carrier Supply
80 PSI
Split
8
Septum Purge
EPC Module
Frit
Valve
Frit
Valve
Valve
PS
FS
PS
Split Vent Trap
PTV Inlet Weldment
FS = Flow Sensor
PS = Pressure Sensor
Column
Stage 3. Purge and cleanup
The split valve opens again and the system returns to the Stage
1 configuration but with different setpoints. The PTV inlet is
flushed. Additional ramp rates are available to thermally clean
the inlet or to reduce inlet temperature after sample transfer.
This can extend the life of the liner.
Temperature, pressure, and flow considerations
The solvent vent mode goes through three distinct pneumatic
states; venting, sample transfer, and purging. The vent portion
allows the inlet pressure and the vent flow to be adjusted to
optimize solvent elimination. The transfer state mimics
traditional splitless operation and transports the analytes from
the liner to the column. The purging mode allows the user to
prepare the inlet for the next run.
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Inlets
A fundamental difficulty with solvent vent mode is the potential
loss of volatile analytes with the solvent. Several solutions are
possible for this situation:
• The inlet liner can be packed with a more retentive material,
such as Tenax. This greatly improves volatile analyte
recovery but may impact recovery of higher boiling materials.
• Some of the solvent can be left in the liner when sample
transfer begins. The residual solvent acts like a stationary
phase and retains volatile material, but at the expense of a
larger solvent peak.
• The inlet temperature can be reduced. This reduces the
vapor pressure of the volatile analytes and permits higher
recoveries.
Solvent removal can be speeded up by:
• Reducing pressure in the inlet during sample
introduction—the Vent pressure parameter
• Increasing flow through the inlet—the Vent flow parameter
While all these possibilities do complicate use of the PTV, they
provide increased flexibility and new potential to solve difficult
problems.
Sequence of operations
These are the steps in a typical analysis using the solvent vent
mode:
Table 44
The solvent vent process
Step
1
Before injection
Parameter
Value
Flow at split vent
Either Purge flow or Saver flow
Inlet pressure
Derived from column setpoint
The system is resting, with Purge flow (or Saver flow, if on) through the inlet.
2
Prep Run begins
Flow at split vent
Vent flow setpoint
Inlet pressure
Vent pressure setpoint
Setpoints change to prepare for injection. When GC is ready, the sample is injected. Inlet and oven
temperature program Init times begin. Solvent venting and analyte trapping begin.
3
At Vent end time
Flow at split vent
None, split valve closed
Inlet pressure
Column pressure setpoint
Solvent venting ends, analyte transfer begins as inlet heats up.
4
242
At Purge time
Flow at split vent
Purge flow setpoint
Advanced User Guide
8
Inlets
Table 44
The solvent vent process (continued)
Step
Parameter
Value
Inlet pressure
Column pressure setpoint
Analyte transfer ends, inlet is purged of residual vapor. Analysis begins.
5
At Saver time
Flow at split vent
Saver flow setpoint
Inlet pressure
Column pressure setpoint
Analysis ends, carrier flow reduced to save gas (if Saver is on).
Some important points
• The flow through the column is governed by the pressure in
the inlet. This is controlled, during the analysis part of the
process, by the flow or pressure setpoint or program entered
for the column.
• The controlling times must be in the order shown; Vent end
time before Purge time and PTV temperature Initial time before
Saver time.
• Vent end time must occur before the inlet starts to heat and
release analytes.
• Purge time must occur before the oven begins to heat and
move sample through the column.
Timelines
Time increases downward; all other quantities increase to the
right.
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Inlets
Time
Oven temperature
Inlet temperature
Inlet pressure
Split vent flow
Controlled by column
flow or pressure setpoint
or program
Between runs
Prep Run
Start Run
Vent pressure
Saver or
Purge flow
Vent flow
Initial time
Vent end time
Rate 1
Inlet is
pressure
controlled
Initial time
Final temperature 1
Final time 1
Purge time
Rate 1
Other rates,
temperatures,
and times, if
desired
Controlled by
column flow or
pressure setpoint
or program
Purge flow
Final temperature 1
Final time 1
Saver time
Other rates,
temperatures,
and times, if
desired
Saver flow,
if on
When is Start Run?
Both the inlet and oven temperature programs begin at Start
Run. All times—such as Purge time—are measured from Start
Run. When does Start Run occur?
• If the sample is injected manually, Start Run occurs when the
user presses the [Start] key.
• If a single injection per run is made using an autosampler,
Start Run occurs when the syringe carrier moves down to
make the injection.
• If multiple injections per run are made using an autosampler,
Start Run occurs when the syringe carrier moves down to
make the first injection of the set. There are no Start Run
signals for the rest of the injections in the set.
These additional injections take time. The inlet and oven
temperature programs, mainly the Initial time values, must be
adjusted to allow for this. So must the various time values that
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Advanced User Guide
8
Inlets
control the inlet operation. This is discussed in more detail
under “To develop a PTV method that uses large volume
injection” on page 247.
Setting parameters for solvent vent operation
Mode:
The current operating mode—solvent vent.
Temperature
Actual and setpoint initial inlet temperatures.
Initial time The time, measured from Start Run, when the
initial inlet temperature hold ends. Must be greater than Vent
end time.
Rate #
Temperature program rate for inlet thermal ramps.
Final temperature #
3.
Final inlet temperature for ramps 1, 2, and
Final time # Hold time at Final temp #. This time is a duration; it
is not measured from Start Run.
Pressure Actual and setpoint inlet pressure before and after
the vent period. It sets the starting point of column head
pressure.
Vent pressure The inlet pressure during the vent period. By
decreasing the inlet pressure while venting, solvent elimination
proceeds faster. Also, the pressure reduction decreases the
amount of carrier gas—and solvent vapor—that enters the
column during this time.
Users select from 0 to 100 psig. If 0 is chosen, the inlet uses the
lowest pressure possible at the given vent flow. Table 45 shows
approximate values for this minimum at various vent flows of
helium. Pressures less than those in the table are not possible
unless the flow is reduced.
Table 45
Advanced User Guide
Minimum attainable pressures
Vent flow (mL/min)
Actual vent pressure at
“0“ psig setpoint
Actual vent pressure at
“0” kPa setpoint
50
0.7
5
100
1.3
10
200
2.6
18
500
6.4
44
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Table 45
Minimum attainable pressures
Vent flow (mL/min)
Actual vent pressure at
“0“ psig setpoint
Actual vent pressure at
“0” kPa setpoint
1000
12.7
88
Vent flow The flow of carrier gas out the split vent during the
vent period. Higher flows sweep the liner more quickly and
reduce the time for solvent elimination. For most columns,
100 mL/min vent flow eliminates solvent at an acceptable rate
but puts minimal material on the column.
Vent end time The time, measured from Start Run, when
solvent venting ends. For large volume injections, this time is
normally greater than the time for the injection to complete.
Purge time The time, measured from Start Run, when sample
transfer ends. It began at Vent end time.
Purge flow The flow of carrier gas to the inlet beginning at
Purge time.
Total flow
The actual flow into the inlet.
Septum Purge
Gas saver
Flow through the septum purge vent
On to reduce split vent flow at Saver time
Saver flow
Reduced split vent flow, at least 15 mL/min
Saver time
Time when flow is reduced to save gas
If the column is defined
1 Press [Front Inlet].
246
2
Scroll to Mode: and press [Mode/Type]. Select Solvent vent.
3
Enter a Vent pressure, a Vent flow, and a Vent end time.
4
Set the inlet temperature and ramps, as desired.
5
Enter a Purge time and a Purge flow.
6
If desired, turn Gas saver on. Make certain the time is set
after the Purge time.
7
Press [Prep Run] (see “Pre Run and Prep Run” on page 171)
before manually injecting a sample.
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If the column is not defined
1 Set up the parameters as described for the defined column
case.
2
Set Total flow greater than the column flow plus the septum
purge flow to guarantee adequate column flow.
To develop a PTV method that uses large volume injection
This topic provides a recommended way to change from a
splitless injection using a split/splitless inlet to a solvent vent
mode injection using a programmable temperature vaporization
inlet (PTV). It applies mainly to large volume injections (LVI)
using a PTV, but the concepts can apply to general PTV use. This
topic does not consider all items that can impact an analysis, for
example the liner, solvent, analyte boiling points, or polarity.
This topic also assumes knowledge of your data system—when
to save a method, how to start a run, how to set up a single run,
etc.
The main advantage of the PTV inlet's solvent vent mode is that
you can inject slowly into the inlet, allowing large amounts of
solvent to evaporate in the liner (not in the split vent line). This
concentrates the analytes prior to injection. It requires an
injector with variable speed injections, a “large” syringe, and
knowledge of the sample and the solvent.
When developing a solvent vent method, the goal is to determine
the injection rates and temperatures needed to evaporate the
solvent at the rate it enters the inlet. The development
technique is to gradually scale up to an injection amount that
produces a useful response. The most significant parameters
are:
Temperature Hold the inlet temperature at or slightly below the
solvent boiling point until after all the sample has been injected.
This is important so that you do not boil away more volatile
analytes, or boil away the solvent in the needle and trap your
analytes there. An additional point to consider is that the
boiling point of the earliest eluting analyte should be 100 °C less
than the boiling point of the solvent.
Injection speed Estimate the evaporation rate of solvent exiting
the needle based on solvent type, inlet temperature, vent flow,
and pressure. Start with about half that number. Note that you
have to make sure that you configure the syringe properly. If
not, you will over- or under- load the inlet.
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Vent end time The vent end time setpoint must be greater than
the time the needle spends in the inlet. If the vent time is too
short, you will overload and contaminate the column and inlet.
Adjust the vent time as you scale up the method.
If using a PTV with an MSD, another tip for method
development is to scan for solvent ions. Detecting the solvent
ions can be useful in troubleshooting residual solvent bleed onto
the column.
To develop a PTV method for large volume injection, try the
following:
1 Determine a small injection volume that works on a
split/splitless inlet in splitless mode or the PTV in splitless
mode. Choose a volume that does not currently overload the
inlet.
2
Start with a 5–10 uL syringe and make sure the syringe is
properly configured in the instrument and data system.
3
Make sure the column is configured.
4
Set up the inlet to perform a 1 uL injection.
Use the splitless method conditions, except:
• Start with the inlet temperature cold, near but slightly
below the solvent boiling point. For example, if using
methylene chloride (boiling point 39 °C), start with a
temperature of 30–39 °C.
• Use Splitless mode.
• Ramp to the normal splitless inlet temperature.
5
Note the response achieved.
6
Next, change the inlet mode to Solvent vent.
7
Check the injector timings.
a Install an empty sample vial in the injector turret or tray.
b Input the injection rate (Sample Draw Speed, Sample Disp
Speed, and Inject Dispense Speed rates) for the injector and
increase the injection volume to 5 uL.
c Enter draft Solvent vent parameters:
• Set a Vent flow of 100 mL/min as a starting point.
• Keep the inlet isothermal for now.
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• Enter a Vent pressure of 0 psi (0 kPa) and Vent end time of
0.1 minutes.
d Make an injection using the empty vial. Use a stopwatch
or your GC's timer feature to time how long the needle is
in the inlet.
8
Enter revised Solvent vent mode parameters.
• Set the method's Vent end time to be about 0.05 min longer
than the time the needle spends in the inlet.
• Set the inlet temperature Initial time to be about 0.05 min
longer than the Vent pressure time.
• Program the inlet to ramp quickly to the injection
temperature. Make sure the ramp starts after the Vent end
time.
• Set the Purge Flow to 30 mL/min. Set the purge time to be
the vent pressure Vent end time + 1 minute.
9
Make a 5 uL injection of your standard. You should see 5
times the response.
If the response of all analytes is too low:
• The dispense speed is too fast. Liquid was injected into
the inlet and pushed out the vent.
• The vent time is too long. The inlet started to heat while
the vent was open.
If the response of early eluters is too low:
• The inlet temperature is too high.
• The Vent flow is too high.
If the response of late eluters is too low:
• The purge time is too short.
• The final inlet temperature is too low.
10 If you need more injection volume and the 5 uL worked to
give 5 times the response, change the syringe to a larger one,
for example, 50 uL.
11 Set up the data system to perform a 25 uL injection.
12 Configure the syringe. Make sure the plunger speeds on the
injector are still set properly.
13 Recheck the injector timings. See the step above.
14 Set a new vent time and initial inlet temperature time based
on the new time the needle spends in the syringe.
15 Make a 25 uL injection of your standard. Again, you should
see 5 times the response. If not, see step 13.
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16 If you need more response, repeat steps 10 through 15 to
increase to larger volume. See the next section. Try
performing 5 x 5 uL injections, then 5 x 50 uL injections.
Multiple injections with the PTV inlet
The preferred technique for concentrating analytes in the inlet
liner is to use a single, large volume injection. Using a high
capacity syringe and one septum puncture reduces the
possibility of contamination and generally improves results
when compared against a multiple septum puncture technique.
However, if needed, you can perform multiple septum punctures
during the vent time. This technique requires an Agilent data
system and automatic liquid sampler.
Data system requirements
An Agilent data system is necessary for multiple injection
because the needed parameters are not available through the
GC keyboard.
GC ChemStation
MSD ChemStation
EZChrom
Software revision B.04.01 SP1 or later.
Software revision E.02.00 SP2 or later
Software revision 3.3.2 or later
Setting parameters for the inlet in solvent vent mode
Set or configure the following parameters in the data system's
7890A GC method editor.
Syringe size — Verify the syringe size is configured correctly.
The configured syringe size changes the available choices for
injection volume.
Injection volume — Select the injection volume, then enter a
number of injections. The total injection volume will be
displayed.
Multiple Injection Delay — A pause time, in seconds, between
injections. This is added to the minimum hardware cycle time.
Preinjection washes and pumps are performed only before the
first injection of a multiple injection set.
Postinjection washes are performed only after the last injection
in a multiple injection set.
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8
An example
These values were used for a sample with a broad range of
boiling points.
Table 46
Name
Value
Sample
C10 to C44 hydrocarbons in hexane
Mode
Solvent vent
MMI liner
Glass wool packed
Injection volume
One 10.0 μL injection (25 μL syringe)
Injection speed
Fast
Column
30 m x 320 μm x 0.25 μm -5, part
number 19091J-413
Column flow
4 mL/min constant flow
Table 47
Inlet parameters
Name
Value
Name
Initial temp
40 °C
Rate 2 (off)
Initial time
0.3 min
Pressure
15.6 psig
Rate 1
720 °C/min
Vent pressure
0.0 psig
Final temp 1
450 °C
Vent flow
100 mL/min
Final time 1
5 min
Vent end time
0.2 min
Rate 2
100 °C/min
Purge time
2.0 min
Final temp 2
250 °C
Purge flow
50 mL/min
Final time 2
0 min
Table 48
Advanced User Guide
General parameters
Value
Oven parameters
Name
Value
Initial temp
40 °C
Initial time
2.5 min
Rate 1
25 °C/min
Final temp 1
320 °C
Final time 1
10.0 min
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Table 48
Oven parameters
Name
Value
Rate 2 (off)
Table 49
Detector parameters
Name
Value
Detector
FID
Detector temp
400 °C
Hydrogen flow
40 mL/min
Air flow
450 mL/min
Makeup (N2)
45 mL/min
C20
These results were compared with a splitless analysis of the
same sample, which should produce 100% recovery of all
analytes. The data showed that, under these conditions,
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compounds above C20 were completely recovered and that the
recovery was independent of injection size. Compounds lower than
C20 were partially vented with the solvent.
Possible adjustments
Depending on what you are trying to accomplish, you have a
number of possible adjustments available.
To eliminate more solvent
• Increase the vent end time, inlet initial time, and purge time.
This will not affect analytes that are quantitatively trapped
but will eliminate more of the solvent peak.
• Increase the vent flow to sweep the liner more rapidly with
the same inlet timing. Increasing vent flow raises vent
pressure if it is set to 0. This puts more solvent onto the
column.
• Raise the inlet initial temperature to vaporize more solvent
and allow more to be eliminated. This also increases the loss
of volatile analytes since their vapor pressures also increase.
To improve recovery of low boiling analytes
• Reduce inlet temperature to lower the vapor pressure of the
analytes and trap them more effectively. This also reduces
solvent vapor pressure and more time will be needed to
eliminate it.
• Use a retentive packing in the liner. Materials such as Tenax
permit higher recovery of volatile analytes but may not
release higher boiling compounds. This must be considered if
quantitation on these high boiling peaks is desired.
• Leave more solvent in the liner. The solvent acts as a pseudo
stationary phase and helps retain volatile analytes. This
must be balanced against the detector’s tolerance for solvent.
An example—continued
The single injection example shown on the last few pages makes
it clear that a 10 μL injection does not overload the glass wool
packed liner. This means that multiple 10 μL injections are
possible.
It was decided to make 10 injections per run, each of 10 μL size.
This would increase analytical sensitivity substantially. No
adjustments were made to improve recovery of the low boilers
since the purpose of this analysis was to detect and measure the
high boiling components.
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After timing a trial set of 10 injections, the total time for the
multiple injection set was measured to be approximately
1.3 minutes. The following timing changes were made:
Table 50
Modifications
Parameter
Increased from
To
Inlet Init time
0.3 minutes
1.6 minutes
Vent end time
0.2 minutes
1.5 minutes
Purge time
2.0 minutes
3.0 minutes
Oven Init time
2.5 minutes
3.0 minutes
The result is shown in the next figure. Note the difference in the
vertical scale (5000 versus 500).
C20
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About the Volatiles Interface
The volatiles interface provides a simple, reliable way to
introduce a gas sample into your GC from an external device
such as a headspace, purge and trap, or air toxic sampler.
Manual syringe injections cannot be made with this interface.
The interface has a small volume and is highly inert, ensuring
high sensitivity and resolution for applications requiring trace
level detection.
The figure shows the pneumatics in the split mode.
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
Valve
PS
FS
PS
Frit
Gas Sampling Valve
Headspace
Purge and Trap
Split Vent Trap
FS = Flow Sensor
PS = Pressure Sensor
Column
Total flow to the interface is measured by a flow sensor and is
divided into two streams. One stream connects to the septum
purge regulator; the other connects to a frit block. At the frit
block, the flow is further divided. The first stream goes to the
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gas- phase sampler and from there is introduced into the
interface. The second stream, called the pressure sensing line,
passes through the frit block and is measured by a pressure
sensor. This stream also provides a trickle flow to the interface.
VI operating modes
There are three modes of operation—split, splitless, and direct.
The pneumatics differ for each operating mode and are
discussed in detail in the rest of this document.
Table 51 summarize some issues to consider when choosing an
operating mode. Specifications for the interface are also listed.
Table 51
Overview of the volatiles interface
Mode
Sample
concentration
Sample to
column
Split
High
Very little, most is
vented
Splitless
Low
All
Can switch to split
mode electronically.
Direct
Low
All
Must physically
disconnect split vent,
plug the interface, and
reconfigure the GC.
Maximizes sample
recovery and eliminates
possibility of
contamination to
pneumatic system.
Table 52
Specifications of the volatiles interface
Specification
Comments
Value/Comment
Deactivated flow path
256
Volume
32 µL
Internal dimensions
2 mm by 10 mm
Maximum flow to interface
100 mL/min
Split range
Depends on column flow
Typically no split to 100:1
Temperature range
10 °C above ambient (with oven at
ambient) to 400 °C
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Table 52
8
Specifications of the volatiles interface (continued)
Specification
Value/Comment
Recommended temperature:
≥ transfer line temperature of the
external sampling device
About the VI split mode
When you introduce a sample in the split mode, a small amount
of the sample enters the column while the major portion exits
from the split vent. The ratio of split flow to column flow is
controlled by the user. The split mode is primarily used for high
concentration samples when you can afford to lose most of the
sample out the split vent and for samples that cannot be diluted.
Split ratio
Because of the interface’s small internal volume, the maximum
total flow to the interface is 100 mL/min. This maximum flow
puts some restriction on the split ratio you can set.
Table 53
Maximum split ratios
Column diameter
(mm)
Column flow
(mL/min)
Maximum split
ratio
Total flow
(mL/min)
0.20
1
100:1
100
0.53
5
20:1
100
Split mode pneumatics
During Pre Run, during sampling, and after sampling, total flow
to the interface is measured by a flow sensor and controlled by
a proportional valve. Flow at the head of the column is
back- pressure regulated. Pressure is sensed upstream from the
proportional valve.
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Inlets
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
Valve
PS
FS
PS
Frit
Gas Sampling Valve
Headspace
Purge and Trap
Split Vent Trap
FS = Flow Sensor
PS = Pressure Sensor
Column
Setpoint dependencies
Some setpoints are interdependent. If you change one setpoint,
other setpoints may change to compensate. With a defined
capillary column, setting column flow or linear velocity will set
the inlet pressure.
Table 54
Setpoint dependencies
When you change
Pressure
258
These setpoints change
Column defined
Column not defined
Column flow*
Split flow
Total flow
No changes
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Table 54
Setpoint dependencies (continued)
When you change
These setpoints change
Column defined
Column not defined
Column flow*
Pressure
Split flow
Total flow
not available
Split flow
Split ratio
Total flow
not available
Split ratio
Split flow
Total flow
not available
Total flow
Split flow
Split ratio
No changes
* This setpoint appears in [Col 1] or [Col 2].
Initial values
Use the information in Table 55 to help you set up the operating
conditions for your interface.
Table 55
Suggested starting values
Parameter
Allowed setpoint range
Suggested starting
value
Oven initial time
0 to 999.9 minutes
After sample on column
Interface temperature
Ambient + 10 °C to 400 °C ≥ Transfer line
temperature
Gas saver time
0 to 999.9 minutes
After sample on column
Gas saver flow
15 to 100 mL/min
15 mL/min greater than
maximum column flow
Setting parameters for the split mode
Mode:
The current operating mode—split
Temperature
Actual and setpoint interface temperatures
Pressure Actual and setpoint interface pressure. Controls
capillary column flow.
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Split ratio The ratio of split flow to column flow. Column flow
is set using [Col 1] or [Col 2]. This parameter is not available if
your column is not defined.
Split flow Flow, in mL/min, from the split vent. This parameter
is not available if your column is not defined.
Total flow
actual
The total flow into the interface, both setpoint and
Septum Purge
Gas saver
Flow through the septum purge vent
On to reduce split vent flow at Saver time
Saver flow
Reduced split vent flow, at least 15 mL/min.
Saver time
Time when flow is reduced to save gas
If the column is defined
1 Press [Front Inlet] or [Back Inlet].
2
Scroll to Mode: and press [Mode/Type]. Select Split.
3
Set the interface temperature.
4
If you want a specific split ratio, scroll to Split ratio and enter
that number. The split flow will be calculated and set for you.
5
If you want a specific split flow, scroll to Split flow and enter
that number. The split ratio will be calculated and set for
you.
6
If desired, turn Gas saver on. Set Saver time after the sample
has been introduced.
7
If Gas saver is on, be certain Auto prep run is On (see “Pre Run
and Prep Run” on page 171) or press [Prep Run] before
introducing the sample.
If the column is not defined
1 Press [Front Inlet] or [Back Inlet].
260
2
Scroll to Mode: and press [Mode/Type]. Select Split.
3
Set the interface temperature.
4
Set Total flow into the interface. Measure flow out of the split
vent using a flow meter.
5
Subtract the split vent flow from Total flow. Subtract the
septum purge flow from the result to get column flow.
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Inlets
6
Calculate the split ratio (split vent flow/column flow). Adjust
as needed.
7
If desired, turn Gas saver on. Set Saver time after the sample
has been introduced.
8
If Gas saver is on, be certain Auto prep run is On (see “Pre Run
and Prep Run” on page 171) or press [Prep Run] before
introducing the sample.
About the VI splitless mode
This mode is used to concentrate sample at the head of the GC
column during desorb. Purge timing delay must take into
consideration the volume of the loop or trap in the external
sampler plus the transfer line versus desorb/total flow rate.
Cryo focussing is required for very volatile samples in splitless
mode.
When you introduce a sample, the split valve remains closed
while the sample enters the interface and is transferred to the
column. At a specified time after the sample is introduced, the
split valve opens.
Splitless mode pneumatics
Before Pre Run When the GC is preparing for sample
introduction, total flow to the interface is measured by a flow
sensor and controlled by a proportional valve. Column flow is
controlled via back- pressure regulation. The split valve is open.
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Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
Valve
PS
FS
PS
Frit
Gas Sampling Valve
Headspace
Purge and Trap
Split Vent Trap
FS = Flow Sensor
PS = Pressure Sensor
Column
During sampling Pressure upsets caused by switching valves
and trap restrictions in the external sampling device can cause
fluctuations in column flow rates. To compensate for this, the
interface is flow controlled during sampling time. The sampling
flow rate is calculated from the pressure setpoint that is active
when sample introduction begins. This flow control starts when
the GC goes into the Pre Run state (when your system is
automated and the Pre Run light is on or during manual
operation when you press [Prep Run]) and ends after the
interface’s Sampling end setpoint expires.
Sampling end is required for purge and trap or thermal
desorption systems and should be set ≥ the sampler desorb
time.
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8
During this user- specified sampling period, the solenoid valve
is closed. Flow to the interface is measured by a flow sensor and
controlled by a proportional valve.
Carrier Supply
80 PSI
Split
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
Valve
PS
FS
PS
Frit
Gas Sampling Valve
Headspace
Purge and Trap
Split Vent Trap
FS = Flow Sensor
PS = Pressure Sensor
Column
After sampling end The solenoid valve opens. The system
returns to the Before Prep Run state. Flow to the interface is
again measured by a flow sensor and controlled by a
proportional valve while column flow is controlled via
back- pressure regulation. The purge flow is controlled by the
user. If desired, gas saver can be turned on at the end of the run.
Setpoint dependencies
Some setpoints in the flow system are interdependent. If you
change one setpoint, other setpoints may change to compensate.
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Inlets
Table 56
Setpoint dependencies
When you change
These setpoints change
Column defined
Purging
Column not defined
You can change the
Pressure and Total flow
setpoints; other
setpoints are not
affected.
Purge flow
Total flow**
Pressure
Total flow**
Column flow*
Column flow*
Pressure
Total flow**
Before and after sampling, not purging
Pressure
Column flow*
Total flow**
Column flow*
Pressure
Total flow**
You can change the
Pressure setpoint; other
setpoints are not
affected.
During sampling:
You cannot change pressure and flow setpoints during sampling time.
* This setpoint appears in the column parameters.
**This value is actual only.
Initial values
The table shows recommended starting values for selected
parameters.
Table 57
264
Suggested starting values
Parameter
Allowed setpoint range
Suggested starting
value
Oven initial time
0 to 999.9 minutes
≥ Interface purge time
Interface temperature
Ambient + 10 °C to 400 °C ≥ Transfer line
temperature
Interface sampling end
0 to 999.9 minutes
0.2 minutes longer than
introduction time
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Table 57
Suggested starting values (continued)
Parameter
Allowed setpoint range
Suggested starting
value
Interface purge time
0 to 999.9 minutes
Gas saver time
0 to 999.9 minutes
Must be after purge time
Gas saver flow
15 to 100 mL/min
15 mL/min greater than
maximum column flow
Setting parameters for the VI splitless mode
Mode:
The current operating mode—splitless
Temperature Actual and setpoint interface temperatures.
Column temperature must be low enough to cold trap the
volatile sample. Cryo focussing is recommended.
Sampling end The sample introduction interval, in minutes.
The flow rate is calculated from the pressure setpoint that is
active at the start of sample introduction.
Set the sampling end setpoint 0.2 minutes longer than the time
the sampler needs to introduce the sample. For example, the
7694 headspace sampler has an Inject time parameter which
controls how long the valve remains in the inject position. If
Inject time is 1 minute, the sampling end setpoint should be set
to 1.2 minutes. If you’re using an 7695 Purge and Trap
Concentrator, set Sampling end 0.2 minutes longer than the
Desorb time parameter.
If your column is defined and you specify a flow or pressure
program for your column, the ramp does not begin until after
the sampling end setpoint expires.
Pressure
kPa.
Actual and setpoint interface pressure in psi, bar, or
Purge time The time, after the beginning of the run, when
purging resumes. Purge time must be greater than Sampl’g end.
Purge flow The flow, in mL/min, from the split vent at Purge
time. You will not be able to access or specify this value if your
column is not defined.
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Total flow When your column is defined, Total flow displays the
actual flow to the interface. You cannot enter a setpoint. If your
column is not defined, Total flow will have both setpoint and
actual values during purge time. All other times, the actual flow
to the interface is displayed.
Septum Purge
mL/min.
Gas saver
Saver flow
Flow through the septum purge vent, at least 15
On to reduce split vent flow at Saver time.
Flow through the split vent after Saver time.
These instructions apply to both column defined and not defined.
1 Press [Front Inlet] or [Back Inlet].
2
Scroll to Mode: and press [Mode/Type]. Select Splitless.
3
Set the interface temperature and a sampling end time.
4
If your column is defined, enter a Purge time and Purge flow.
Turn Gas saver on if desired. Set the Gas saver time after the
purge time and enter a Gas saver flow.
5
If your column is not defined, enter a Purge time (Purge flow is
not available). Set Total flow greater than column flow plus
septum purge flow to guarantee adequate column flow.
6
Make certain Auto Prep Run is On (see “Pre Run and Prep Run”
on page 171) or press [Prep Run] before introducing a sample.
About the VI direct mode
Direct sample introduction permits a quantitative transfer of
analyte without risking contamination to the pneumatic system.
It provides the sensitivity required for air toxic analyses. The
interface’s minimal dead volume also eliminates the potential
interaction of solutes with poorly swept, active surfaces.
To operate in the direct mode, you must physically disconnect
the split vent and reconfigure the GC.
Before Pre Run
The interface is forward pressure controlled; pressure is sensed
downstream from the flow proportional valve.
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Carrier Supply
80 PSI
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
PS
FS
PS
Frit
Gas Sampling Valve
Headspace
Purge and Trap
FS = Flow Sensor
PS = Pressure Sensor
Column
During sampling
Pressure upsets caused by switching valves in the external
sampler can cause fluctuations in column flow rates. To
compensate for this, the interface is flow controlled during
sampling time. The sampling flow rate is calculated from the
pressure setpoint that is active when sample introduction
begins. This flow control starts when the GC goes into the Pre
Run state (when your system is automated and the Pre Run
light is on or during manual operation when you press [Prep
Run]) and ends after the interface’s Sampling end setpoint
expires.
Flow to the interface is measured by a flow sensor and
controlled by a proportional valve.
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Inlets
Carrier Supply
80 PSI
Septum Purge
EPC Module
Frit
Frit
Valve
Valve
PS
FS
PS
Frit
Gas Sampling Valve
Headspace
Purge and Trap
Column
FS = Flow Sensor
PS = Pressure Sensor
After sampling end
The interface is forward pressure controlled; pressure is sensed
downstream from the proportional valve. The system returns to
the idle state.
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Preparing the Interface for Direct Sample Introduction
Before you can operate your interface in direct mode, you must:
• Disconnect the split vent line
• Configure the GC for a direct injection
Disconnecting the split vent line
WA R N I N G
Be careful! The interface may be hot enough to cause burns.
1 Press [Front Inlet] or [Back Inlet]. Turn off the interface
temperature and pressure and allow the interface to cool.
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2
If desired, remove the transfer line by loosening the hex nut
with a wrench.
3
Remove the clamping plate from the interface by loosening
the captive screw with a screwdriver. Put the plate in a safe
place.
4
Carefully lift the interface out of the heater block.
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Inlets
5
Loosen the hex nut connecting the split vent line to the
interface until you can remove the line. Put the line aside.
You do not need to plug it.
6
Install a blanking nut into the split line port and
finger- tighten the nut. Tighten the nut an additional
1/4- turn using two wrenches in opposition.
7
Place the interface in the heater block. Replace the clamping
plate you removed earlier and tighten the screw until snug.
Do not overtighten. If you removed the transfer line, replace
it.
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8
Restore the GC to normal operating conditions. Perform a
leak test on the interface fittings.
Configuring for direct mode
The GC cannot sense the presence of the split vent. When you
disconnect or reconnect the vent, you must configure the GC so
that the pneumatics work properly.
1 Press [Config][Back Inlet] or [Config][Front Inlet].
2
Scroll to Mode and press [Mode/Type].
3
Select Split vent removed. Press [Enter].
4
Press [Back Inlet] or [Front Inlet]. If the inlet is correctly
configured, you will see the Direct injection display.
VI direct mode setpoint dependencies
Some setpoints in the flow system are interdependent. If you
change one setpoint, other setpoints may change to compensate.
Table 58
Setpoint changes
When you change
These setpoints change
Column defined
Before and after
sampling
Column not defined
The Column flow*
setpoint is not available.
Pressure
Column flow*
Total flow**
Column flow*
Pressure
Total flow**
During sampling
You cannot change pressure and flow setpoints
during sampling time.
You can change the
pressure setpoint; other
setpoints are not
affected.
* This setpoint appears in the column parameters
.**This value is actual only
VI direct mode initial values
Use the information in Table 59 to help you set up the operating
conditions for your interface.
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Table 59
Suggested starting values
Parameter
Allowed setpoint range
Suggested starting
value
Oven initial time
0 to 999.9 minutes
≥ interface sampling end
Interface temperature
Ambient + 10 °C to
400 °C
≥ transfer line
temperature
Interface sampling end
0 to 999.9 minutes
0.2 minutes longer than
actual sampling time
Setting parameters for the VI direct mode
Temperature
Actual and setpoint interface temperatures
Sampling end The sample introduction interval, in minutes.
The flow rate is calculated from the pressure setpoint that is
active at the start of sample introduction.
Set Sampling end 0.2 minutes longer than the time the sampler
needs to introduce the sample. For example, the 7694
headspace sampler has an Inject time parameter which controls
how long the valve remains in the inject position. If Inject time is
1 minute, Sampling end should be set to 1.2 minutes. If you’re
using a 7695 Purge and Trap Concentrator, set Sampling end
0.2 minutes longer than the Desorb time parameter.
If your column is defined and you specify a flow or pressure
program for your column, the ramp does not begin until after
Sampling end expires.
Pressure Actual and setpoint interface pressure before a run
and after sampling time.
Total flow The actual flow to the interface. This is a reported
value, not a setpoint.
Septum Purge
30 mL/min.
Flow through the septum purge vent, range 0 to
These instructions apply to both column defined and column
not defined.
1 Press [Front Inlet] or [Back Inlet].
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2
Confirm that your GC is configured for direct injection.
3
Set the interface temperature.
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Inlets
Advanced User Guide
4
Set Sampling end at 0.2 minutes longer than the sample
introduction time.
5
Make certain Auto Prep Run is On (see “Pre Run and Prep
Run” on page 171) or press [Prep Run] before introducing a
sample.
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Agilent 7890A Gas Chromatograph
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About the Oven 276
Oven safety 276
Configuring the Oven 277
Cryogenic Operation 278
Cryogenic setpoints 278
About Oven Temperature Programming 280
Programming setpoints 280
Oven ramp rates 281
Setting the oven parameters for constant temperature 282
Setting the oven parameters for ramped temperature 282
About the Oven Insert 284
Selecting the correct packed glass column type 285
About the column modes 285
Select a column mode 286
Setting the column parameters for constant flow or constant
pressure 287
Enter a flow or pressure program (optional) 287
Programming column pressure or flow 288
About Columns 285
Backflushing a Column 289
Backflushing when connected to an MSD 289
Nickel Catalyst Tube 295
About the nickel catalyst tube 295
Nickel catalyst gas flows 295
Setting temperatures for the nickel catalyst tube 296
Agilent Technologies
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About the Oven
Table 60
Oven capabilities
Capability
Range
Temperature range
–80 °C (liquid N2) or –40 °C (CO2) to
the configured limit
Maximum temperature
450 °C
Temperature programming
Up to six ramps
Maximum run time
999.99 minutes
Temperature ramp rates
0 to 120 °C/min, depending on
instrument configuration
Oven safety
For safety, opening the oven door turns off power to the oven
heater, fan, and cryogenic valve (if installed) but maintains the
setpoints in memory.
Closing the oven door returns the oven to normal operation.
If the oven cannot attain or maintain an entered setpoint
temperature during normal above- ambient operation, a
problem is assumed and the oven is switched off.
Possible problems include:
• The oven vent flaps not working
• The oven fan, heater, or temperature sensor not working
properly
• An electronic problem
When a shutdown occurs, the Off line in the oven parameter list
blinks and the oven remains off until switched on again by
pressing [Oven][On] or by editing the Temperature setpoint.
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Configuring the Oven
Oven configuration sets maximum temperature, equilibration
time the cool down mode, and the cryogenic setpoints, if cryo is
installed.
Maximum temperature Maximum allowable oven temperature
setpoint. Some accessories, such as the valve box, valves and
columns have specific temperature limits. When configuring
Maximum temperature, these limits should be considered so that
the accessories are not damaged. Oven setpoints are verified as
they are entered; a message is displayed when an entered
setpoint is inconsistent with a previously defined maximum.
Equilibration time The time required for the oven temperature
to equilibrate after temperature is modified. Equilibration time
begins when the actual oven temperature comes within 1 °C of
the oven temperature setting. The Equilibration time setpoint can
be 0 to 999.99 minutes.
Cryo
See “Cryogenic Operation.
External oven mode
Press the GC [Info] key for details.
Slow oven cool down mode During the oven cooling period, the
fan can operate at full speed or at a reduced speed. This
parameter makes the choice.
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Cryogenic Operation
The cryogenic valve lets you operate the oven below ambient
temperature. Minimum attainable oven temperature depends on
the type of valve installed.
The GC senses the presence and type of cryogenic valve and
disallows setpoints if no valve is installed. When cryogenic
cooling is not needed or cryogenic coolant is not available, the
cryogenic operation should be turned off. If this is not done,
proper oven temperature control may not be possible,
particularly at temperatures near ambient.
Cryogenic setpoints
Equilibration time
Cryo
Set from 0 to 999.999 minutes.
[ON] enables cryogenic cooling, [OFF] disables it.
Quick cryo cool This is separate from Cryo. Quick cryo cool cools
the oven faster after a run than it would without assistance.
This is useful when maximum sample throughput is necessary,
however it does use more coolant. Quick cryo cool turns off soon
after the oven reaches its setpoint and Cryo takes over, if needed.
Ambient temp The temperature in the laboratory. This setpoint
determines the temperature at which cryogenic cooling is
enabled.
• Ambient temp + 25 °C, for regular cryo operation
• Ambient temp + 45 °C, for Quick Cryo Cool.
Cryo timeout Cryo timeout occurs, and the oven shuts off, when
a run does not start within a specified time (10 to 120 minutes)
after the oven equilibrates. Turning cryo timeout Off disables
this feature. We recommend that it be turned On because cryo
timeout conserves coolant at the end of a sequence or if
automation fails.
Cryo fault Shuts the oven down if it does not reach setpoint
temperature after 16 minutes of continuous cryo operation.
Note that this is the time to reach the setpoint, not the time to
stabilize and become ready at the setpoint. For example, with a
cool on- column inlet and cryo control in the track oven mode, it
may take the oven 20 to 30 minutes to achieve readiness.
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If the temperature goes below the minimum allowed
temperature (–90 °C for liquid nitrogen,–70 °C for liquid CO2),
the oven will shut down.
External oven mode Isothermal internal mode and programmed
external oven used to calculate column flow.
Slow oven cool down mode
during cool down.
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On to run oven fan at slow speed
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About Oven Temperature Programming
You can program the oven temperature from an initial
temperature to a final temperature using up to 20 ramps during
a run.
A single ramp temperature program raises the initial oven
temperature to a specified final temperature at a specified rate
and holds at the final temperature for a specified period of time.
Final temperature 1
Final time 1
Rate 1
Rate 2 = 0
Initial time 1
Initial temperature
The multiple- ramp temperature program is similar. You can
program the oven from an initial temperature to a final
temperature, but with various rates, times, and temperatures in
between. Multiple ramps can also be programmed for
temperature decreases as well as increases.
Final temperature 2
Final time 2
Rate 2
Final temperature 1
Initial temperature
Final time 1
Rate 3 = 0
Rate 1
Initial time 1
Programming setpoints
Temperature Starting temperature of a temperature
programmed run. When the program begins, this value is copied
into a temporary setpoint called Init temp. At the end of the run,
Temperature is reset to the value in Init temp and the oven returns
to its starting temperature.
Initial time Time in minutes that the oven will stay at the
starting temperature after a programmed run has begun.
Rate The rate in °C/min at which the oven will be heated or
cooled.
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Final temperature Temperature of the oven at the end of a
heating or cooling rate.
Final time Time in minutes that the oven will be held at the
final temperature of a temperature- programmed rate.
Total length of a run is determined by its oven temperature
program. The maximum allowable time for a run is
999.99 minutes. If the program is still running at that time, the
run terminates.
Post run
This function can be used with both isothermal and
programmed methods. Post run is a period that begins at the
end of the normal run. The parameters are:
• Time—How long is the post run period?
• Temperature—What is the oven temperature during the post
run period?
• Column pressures—What are the pressures at the column ends?
Post run may be used to clean out a column in preparation for
the next run, backflush a column to eliminate high- boilers, and
other functions.
When the Post run Time elapses, the GC returns to the initial
state defined in the current method. If it uses cryogenic cooling
and you do not start another run quickly, you could waste
considerable coolant while waiting for the next run. A solution
is to use a sequence that loads a less wasteful method.
Oven ramp rates
To use the fast oven ramp rates (a 240 V power option is
required), your electric service must be able to supply ≥ 200 V at
≥ 15 Amp.
The highest rate that you can achieve depends on many factors,
including the room temperature, temperatures of the inlets and
detectors, the amount of material inside the oven (columns,
valves, etc.), and whether or not this is the first run of the day.
The optional oven insert for fast chromatography (see “About
the Oven Insert” on page 284), increases oven ramp rates for the
back column. Table 61 lists typical oven ramp rates.
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Table 61
Oven ramp rates
100/120 V oven
ramp rate (°C/minute)
200/220/230/240 V oven
ramp rate (°C/minute)
Temperature
range (°C)
Without
insert
With optional Without
insert
insert
With optional
insert
50 to 70
75
120
120
120
70 to 115
45
95
95
120
115 to 175
40
65
65
110
175 to 300
30
45
45
80
300 to 450
20
35
35
65
Setting the oven parameters for constant temperature
An isothermal run is one in which the oven is maintained at a
constant temperature. For an isothermal run, set Rate 1 to zero.
1 Press [Oven] to open the oven parameter list.
2
Enter the oven temperature for the isothermal run.
3
Enter the number of minutes (Initial time) that you want the
oven to stay at this temperature. This time is the duration of
the run.
4
If Rate 1 is not already 0, enter zero for an isothermal run.
Setting the oven parameters for ramped temperature
Single ramp
1 Press [Oven] to open the oven parameter list.
282
2
Enter a starting temperature (Temperature).
3
Enter the time (Initial time) that you want the oven to stay at
Temperature.
4
Enter the rate (Rate 1) at which the oven temperature is to
change.
5
Enter the final temperature (Final temperature 1).
6
Enter the time (Final time 1) the oven is to hold Final
temperature 1.
7
To end the oven ramp program after Ramp 1, set Rate 2 to
zero.
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Multiple ramps
In a multiple- ramp program, Final time for one ramp is also Initial
time for the next ramp. Thus, there is only one Initial time.
1 Set up the first oven ramp as described in “Single ramp”.
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2
Enter the rate (Rate 2) at which you want the oven
temperature to increase for the second oven ramp.
3
Enter the final temperature (Final temperature 2).
4
Enter the number of minutes (Final time 2) that you want the
oven to hold the final temperature.
5
To end the temperature program after the second ramp, set
Rate 3 to zero.
6
To add additional oven ramps, repeat the steps described.
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About the Oven Insert
The Oven Insert for Fast Chromatography reduces the oven
volume so that the column and sample heat more quickly,
yielding faster separation and faster chromatography.
Furthermore, the smaller volume oven cools faster than a
full- sized oven, reducing the overall analytical cycle time.
Carrying strap
WARNING!
Metal parts may be
hot enough to burn.
The oven insert is used with any inlet, column, and detector
mounted in the back position. It is not compatible with any
accessory which obstructs access to the front of the oven or
which requires the use of either the front inlet or the front part
of the oven.
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About Columns
In all GCs, a sample—which is a mixture of several
components—is vaporized in an inlet, separated in a column,
and examined in a detector.
The column separates components in time because:
• When a vaporized component is presented with a gas phase
and a coating phase, it divides between the two phases
according to its relative attraction to the two phases.
• The “attraction” can be solubility, volatility, polarity, specific
chemical interaction, or any other property that differs from
one component to another.
• If one phase is stationary (the coating) and the other is
moving (the carrier gas), the component will travel at a speed
less than that of the moving phase. How much less depends
on the strength of the attraction.
• If different components have different “attractions”, they will
separate in time.
Selecting the correct packed glass column type
This topic is covered in the Maintenance manual. See To attach
a packed column to the purged packed inlet for details.
About the column modes
The flow modes available are determined by the GC inlet’s
control mode. When the inlet’s control mode is set to Pressure
control, all of the flow modes and pressure modes below are
available for the column. When the inlets control mode is set to
Flow control, the column’s mode is not selectable. For an inlet’s
mode of Flow control, only column flow can be entered.
The flow modes
Flow rates are corrected to NTP (normal temperature and
pressure, 25 °C and 1 atmosphere.
• Constant flow—Maintains a constant mass flow rate of
carrier gas in the column throughout the run. If the column
resistance changes due to a temperature program, the
column head pressure is adjusted to keep the flow rate
constant. This can shorten runs significantly.
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• Ramped flow—Increases the mass flow rate in the column
during the run according to a program you enter. A column
flow profile can have up to three ramps, each consisting of a
programmed increase followed by a hold period.
The pressure modes
The pressure modes are not available if the column is not
defined or the inlet’s mode is set to Flow control.
Pressures are gauge pressures—the difference between the
absolute pressure and the local atmospheric pressure. Because
most detectors present little resistance to the column flow, the
gauge pressure at the column head is usually the same as the
pressure difference between column inlet and exit. The mass
selective detector and the atomic emission detector are the
exceptions.
• Constant pressure—Maintains a constant gauge pressure at
the head of the column throughout the run. If the column
resistance and gas density changes during a run, the gauge
pressure does not change but the mass flow rate does.
• Ramped pressure—Increases the column head gauge
pressure during the run according to a program you enter. A
column pressure profile can have up to three ramps, each
consisting of a programmed increase followed by a hold
period.
Select a column mode
The column’s mode parameter is not available if the inlet’s
mode parameter is set to Flow control.
When a splitter controlled by a PCM or AUX pressure is used to
divide flow between multiple columns, only the mode setting of
the lowest column number configured determines the mode
used. All other column mode settings exiting the splitter are
ignored by the GC.
1 Press [Col 1] or [Col 2], or press [Aux col #] and enter the
column number.
2
Scroll to the Mode line.
3
Press [Mode/Type] to see the column mode list.
4
Scroll to the column mode you want. Press [Enter].
This completes column mode selection. Next you must specify
the inlet conditions either during the entire run (if you selected
either of the constant modes) or at the beginning of the run (if
you selected either of the ramped modes).
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Setting the column parameters for constant flow or constant pressure
If the column is defined, you can enter any one of these
quantities—the GC will calculate and display the other two.
For example, you may have selected Constant pressure as the
column mode. You decide to specify, as a starting condition, the
column flow. The GC will compute the pressure necessary to
achieve this flow (as well as the average linear velocity) and
hold this pressure constant during the run.
If you select Constant flow as the mode and specify column flow
as the initial condition, the GC will still calculate the pressure
necessary to achieve this flow, but it will adjust the pressure as
necessary to maintain constant flow.
If the column is not defined, you can enter only pressure.
Constant flow can still be specified, but the GC cannot know
what the flow is.
1 Press [Col 1] or [Col 2], or press [Aux col #] and enter the
column number.
2
Scroll to the Pressure or Flow or Velocity line.
3
Type the desired initial value, followed by [Enter]. The GC
will compute and display the other two values. Adjust them,
if you choose to, by repeating steps 2 and 3 but note that
changing any one changes all three.
This completes setting the initial carrier gas condition.
Enter a flow or pressure program (optional)
If you selected either the ramped pressure or ramped flow
column mode, the column parameter list contains entries for
setting up a ramp program.
You begin with an initial value, either Initial Pressure or Initial
Flow, and an Initial time. At the end of that time, Rate 1 begins and
runs until it reaches Final pressure (or Final flow). It remains at
that value for Final time 1. You can then add a second and third
ramp, each consisting of a Rate, a Final value (pressure or flow),
and a Final time.
The program ends when it reaches a Rate that is set to 0 (Off).
When a flow or pressure program is running, the Pressure, Flow,
and Velocity lines that you used to set constant conditions show
the progress of the program.
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The oven program determines the length of the run. If a flow or
pressure program ends before the analytical run does, the flow
(or pressure) remains at the last final value.
Programming column pressure or flow
1 Press [Col 1] or [Col 2], or press [Aux col #] and enter the
column number.
288
2
Scroll to Initial pressure (or Initial flow). Type the desired value
and press [Enter].
3
Similarly, enter a value for Initial time. This completes the
initial part of the program.
4
To begin a ramp, enter a positive value for Rate 1. It does not
matter whether you are programming up or down—the rate
is always positive.
5
If Rate 1 is zero, the program ends here. If you enter any
other value, the Final value lines for the first ramp appear
and the cursor moves to the line.
6
Enter values for Final pressure 1 (or Final flow 1) and Final
time 1. This completes the first ramp.
7
To enter a second ramp, scroll to the appropriate Rate line
and repeat steps 5 and 6. A maximum of 20 ramps can be
entered.
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Backflushing a Column
Backflush is a means of discarding high- boilers from a column
after the peaks of interest have eluted. It saves analysis time
and has these additional benefits:
• Longer column life
• less high temperature exposure
• removal of high- boilers
• protection from air and water at high temperatures
• Less chemical background
• ghost peaks
• “wrap- around” of late eluters from previous runs
• stationary phase decomposition peaks
• Less contamination of the mass selective detector (MSD)
source, if using MSD
• longer time between source cleanings
• higher stability of calibrations
You will need to experimentally determine the correct
flow/pressure settings and the backflush time appropriate for
your analysis. Determine the correct values by testing the
backflush method, then running a blank to check for residual
late eluters.
CAUTION
Only backflush an inlet that has a split vent line with a chemical trap,
such as the split/splitless, PTV, and VI. Attempts to backflush using
other inlet types will most likely damage the pneumatics flow
modules.
Refer to the Agilent web site at http://www.agilent.com/chem
for example backflush applications, especially if using an MSD.
Backflushing when connected to an MSD
If using an MSD with the GC, backflushing becomes more
complex. Set up backflush as a post run event by using the
Backflush Wizard present in the MSD Productivity
ChemStation.
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Backflushing using a capillary flow technology device
Because the following capillary flow technology (CFT) devices
connect to a controlled carrier gas supply, they can be used to
backflush a column:
• G2855B Capillary Flow Technology Deans Switching System
• G3180B Capillary Flow Technology Two- Way Splitter (with
makeup gas)
• G3183B Capillary Flow Technology Three- Way Splitter
• G3185B QuickSwap Accessory
A conceptual diagram for a simple setup is shown in the figure.
Split Vent
Trap
Auxiliary
EPC/PCM
Detector
CFT Device
Inlet
Column
After the last analyte of interest elutes, you can program a
decrease in inlet column flow with an increase in the
pressure/flow from the Aux EPC or PCM connected to the CFT
device, thereby reversing column flow and forcing the
remaining analytes off the column and out of the inlet split vent.
You can do this using a post run program or as a ramped
pressure or flow program.
To set up a post run backflush
A main advantage of the post- run backflush method is that the
GC turns off detection during this time. If using an MSD, this
helps prevent damage to the detector and is the recommended
backflush method.
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If using an Agilent data system, a Backflush Wizard provides a
straightforward interface for making these settings.
1 Verify that all columns are properly configured.
2
Since the backflush will run as a post- run program, set the
method so that the oven program ends after the last peak of
interest returns to baseline, or after reaching the last
temperature of interest.
3
Press [Post Run] and enter the backflush duration as the Time.
• The oven temperature and column pressure/flow
setpoints for installed columns appear.
• Whether you can enter a pressure or flow for a column
depends on its mode (pressure or flow).
4
Enter the oven temperature for the backflush.
5
Enter the backflush flow(s) or pressure(s).
If in flow mode:
• Enter a negative flow for the column connected between
the inlet and the CFT device. The GC will automatically
establish the corresponding pressures needed in the inlet
and the CFT device.
• Increase the flow rates in the column(s) connected
between the CFT device and the detector(s).
If in pressure mode:
• Set the pressure of the column connected between the
inlet and the CFT device to 0.000. This turns off flow from
the inlet.
• Increase the pressure of the primary column connected
between the CFT device and the detector(s). This creates
the backward flow through the column and increases the
flow through any connected detectors.
When developing the backflush portion of your method,
consider the following:
• Ensure that the split vent flow setpoint is at least 25 mL/min
and at least 50% more than the column backflush flow rate.
• If using gas saver, ensure that the gas saver flow setpoint is at
least 25 mL/min and at least 50% more than the column
backflush flow rate.
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To backflush using a ramped pressure program
In this case, the backflush occurs as part of the run, so the
detectors continue to collect data. During the backflush, you
may wish to turn off data collection in the data system.
CAUTION
To avoid damage to an MSD, Agilent strongly recommends setting
up backflush as a post run event, not as part of a ramped column
program. If you still choose to backflush as part of a run, be very
careful that the flow into the MSD does not exceed the limits of the
vacuum pump.
1 Verify that all columns are properly configured.
2 Enter all method parameters for the analysis: sampler
parameters, inlet parameters, oven temperature profile,
detector flows and temperatures, and so forth.
3 Program the oven for the backflush.
• Include any temperature profile needed for backflush.
• Set the total run time to include sufficient time for
backflush.
4
Program the pressure ramp for the column installed between
the inlet and the CFT device. After the last analyte elutes or
after reaching the last temperature of interest, program a
fast ramp (for example, 30 psi/min) with a final pressure of
0.
5
Program the pressure ramp for the primary column installed
between the CFT device and the detector. The pressure
should increase slightly during the backflush duration so
that the flow into the detectors remains relatively stable.
If you turned off data acquisition in a data system during
backflush, remember to turn it on again at the end of the run.
To backflush using a ramped flow program
In this case, the backflush occurs as part of the run, so the
detectors continue to collect data. During the backflush, you
may wish to turn off data collection in the data system.
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CAUTION
To avoid damage to an MSD, Agilent strongly recommends setting
up backflush as a post run event, not as part of a ramped column
program. If you still choose to backflush as part of a run, be very
careful that the flow into the MSD does not exceed the limits of the
vacuum pump.
1 Verify that all columns are properly configured.
2 Enter all method parameters for the analysis: sampler
parameters, inlet parameters, oven temperature profile,
detector flows and temperatures, and so forth.
3 Program the oven for the backflush.
• Include any temperature profile needed for backflush.
• Set the total run time to include sufficient time for
backflush.
4
Program the flow ramp for the column installed between the
inlet and the CFT device. After the last analyte elutes or
after reaching the last temperature of interest, program a
fast ramp with a final flow that is negative.
5
Program the flow ramp for the primary column installed
between the CFT device and the detector. Typically hold at
the method’s final value for the backflush duration.
If you turned off data acquisition in a data system during
backflush, remember to turn it on again at the end of the run.
Backflushing using a switching valve
Backflushing is done using a column switching valve controlled
by the Run Table. See “Run Time Programming” on page 14.
The valve is plumbed as follows:
• Position 1 Carrier gas flows through the column to the
detector. This is the normal flow path.
• Position 2 Carrier gas flows through the column toward the
inlet, removing components on the column through the inlet
vent line.
The Run Table contains commands to perform these actions:
• After the last peak of interest appears, switch the valve to
Position 2. Higher boiling peaks are discarded through the
inlet vent.
• At the same time, turn data acquisition off.
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9
Columns and Oven
• At the end of the backflush period (determined
experimentally), switch the valve to Position 1 and turn data
acquisition on. The system is now ready for the next run.
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Columns and Oven
9
Nickel Catalyst Tube
About the nickel catalyst tube
The Nickel Catalyst Tube accessory, G2747A, is used for trace
analysis of CO and CO2 with a flame ionization detector. The gas
sample is separated on the column and passed over a heated
catalyst in the presence of hydrogen, which converts the CO and
CO2 peaks to CH4.
Sample
Carrier gas
Hydrogen
Column
Gas sample valve
Air
Nickel catalyst
FID
Nickel catalyst gas flows
For a standard FID installation:
Table 62
Advanced User Guide
Gas flows for a standard FID
Gas
Flow rate, mL/min
Carrier (helium)
30
FID hydrogen
30 (see Caution)
FID air
400
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9
Columns and Oven
Table 63
CAUTION
Gas flows for a TCD/FID series installation
Gas
Flow rate, mL/min
Carrier (helium)
30
TCD switching flow
25
FID hydrogen
45 (see Caution)
FID air
500
Hydrogen flow is pressure-controlled, where an FID provides a
known resistance. The nickel catalyst tube increases flow
resistance, so that the calibration is no longer valid. You must
measure hydrogen flow with a bubble or similar meter.
The nickel catalyst can be damaged by exposure to air.
Setting temperatures for the nickel catalyst tube
The nickel catalyst tube is usually mounted in the back inlet
position and controlled by the back inlet temperature setpoint.
For most analyses, set these temperatures:
• Nickel catalyst tube—375 °C
• FID—400 °C
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Detectors
About Makeup Gas 298
About the FID 299
About the TCD 304
About the uECD 312
About the NPD 319
About the FPD 331
Agilent Technologies
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About Makeup Gas
Most detectors use a makeup gas to increase the flow rate
through the detector body. This sweeps peaks out of the
detector quickly, avoiding mixing of components and loss of
resolution. This is particularly important with capillary
columns because the column flow rates are so small.
The makeup gas line of your detector parameter list changes
depending on your instrument configuration.
If you have an inlet with the column not defined, the makeup
flow is constant. If you are operating with column defined, you
have a choice of two makeup gas modes.
Constant makeup This mode provides a constant flow of
makeup gas to the detector.
Column + makeup = constant This mode provides a variable
flow of makeup gas to the detector. As column flow increases or
decreases, the makeup flow changes to provide a constant
combined flow to the detector. If you choose this option, enter a
value under Combined flow. The Combined flow line always
displays the same value, while the Makeup line changes as the
actual makeup flow changes.
To change the makeup gas flow mode
1 Press [Front Det] or [Back Det].
298
2
Scroll to Mode. Press [Mode/Type].
3
Scroll to the correct mode and press [Enter].
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Detectors
About the FID
The FID passes sample and carrier gas from the column through
a hydrogen- air flame. The hydrogen- air flame alone creates few
ions, but burning an organic compound increases the number of
ions produced. A polarizing voltage attracts these ions to a
collector located near the flame. The current produced is
proportional to the amount of sample being burned. This
current is sensed by an electrometer, converted to digital form,
and sent to an output device.
The FID uses three supply gases (hydrogen, makeup gas, and
air) and two supply lines. Air flows through one supply line,
while hydrogen mixed with the makeup gas flows through the
other. All three supply gases use:
• A filter frit to protect the flow path and limit the flow rate
• A proportional valve to control the pressure
• A pressure sensor and restrictor to control the valve
The hydrogen and makeup mix outside the flow module and
enter the detector at the base of the jet. Air enters above the jet.
H2
Makeup
Air
EPC Module
Frit
Frit
Frit
Valve
Valve
Valve
Vent
PS
PS
Restrictor
PS = Pressure Sensor
Advanced User Guide
PS
Restrictor
Restrictor
Column
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Table 64
Properties of the FID
Property
Value/Comment
Dynamic range
1 x 107
Sensitivity
10 to 100 picograms of an organic compound
dependent on the molecular structure.
Selectivity
Responds to all organic compounds (C-H bonds)
except those which do not burn or ionize in the
hydrogen-air flame. There is little or no response for
H2O, CO2, CO, N2, O2 CS2 or inert gases.
Formaldehyde and heavily halogenated compounds
give minimal response.
How FID units are displayed in Agilent data systems and on the GC
The GC displays the FID signal in picoamperes (pA). The
following table lists how different data systems convert the
display units to reporting units.
Table 65
Unit conversions
Data system
Height units
LSV (height units)
Area units
Noise (ASTM)*
Agilent data system
1 pA
1.3 x10-4 pA
1 pA-sec
0.038 pA
SIGRange† 0
1 x 10-4 pA
1.3 x 10-4 pA
1 x 10-4 pA
0.038 pA
SIGRange 5
3.2 x 10-3 pA
4.2 x 10-3 pA
3.2 x 10-3 pA
0.038 pA
Analog 1V‡
1.25 x 10-4 pA
device dependent
1.25 x 10-4 pA
0.038 pA
* Noise is recommended maximum when determining MDL.
† SIGRange used with 3393 and 3396 integrators.
‡ Analog 1V is an approximate value.
To light the FID flame
Press [Front Det] or [Back Det], scroll to Flame, then press
[On/Yes].
To extinguish the FID flame
Press [Front Det] or [Back Det], scroll to Flame, then press
[Off/No].
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Detectors
FID automatic reignition (Lit offset)
Lit offset is the expected minimum difference between the FID
output with the flame lit and the output with the flame off. The
GC checks this value during runs and when loading a method.
During a run, if the output falls below the Lit offset value, the FID
will attempt to reignite three times. If after the third attempt
the output does not increase by at least this value, the detector
shuts down all functions except temperature and makeup gas
flow.
When loading a method that includes a Flame On setting, the GC
performs a similar check. If the detector output is less than the
Lit offset, it will attempt reignition after reaching method
setpoints.
The default setting for Lit offset is 2.0 picoamps. This is a good
working value for all but very clean gases and systems. You may
want to lower this setpoint if the detector attempts to reignite
when the flame is still on, thus producing a shutdown.
To change Lit offset:
1 Press [Config][Front Det] or [Config][Back Det].
2
Scroll to Lit offset.
3
Enter the new value and press [Enter].
Recommended starting conditions for new FID methods
See Table 66 for guidelines and rules to select initial detector
settings for new methods.
Table 66
Recommended starting conditions
Combustible gas mix
Make sure that the final hydrogen-to-air ratio is between 8% and 12%
Detector temperature
Set to 20 °C above the highest oven temperature, depending on the column type.
A temperature of 300 °C provides a good starting point and easier ignition, and
minimizes water condensation.
The GC will not attempt to ignite the flame at a temperature <150 °C.
Carrier gas flow (hydrogen, helium,
nitrogen)
Packed columns
Suggest 10 to 60 mL/min
Capillary columns
Suggest 1 to 5 mL/min
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Table 66
Recommended starting conditions (continued)
Detector gases
Flow range mL/min
Suggested flow mL/min
Column plus capillary makeup
10 to 60
30
Hydrogen
24 to 60
30
Air
200 to 600
400
Column plus capillary makeup
10 to 60
30
Hydrogen
24 to 60
30*
Air
200 to 600
400
10 to 60
30
Standard installation
With Nickel Catalyst Accessory:
Standard installation
With Nickel Catalyst Accessory:
TCD to FID series installation
Column plus capillary makeup
TCD switching flow
25
Hydrogen
24 to 60
45*
Air
200 to 600
450
* Detector hydrogen is pressure controlled, where the detector provides a known resistance. If using a nickel catalyst tube, the resistance
changes, and the flow rates displayed by the GC will not be accurate. Measure the actual hydrogen flow using a flow meter at the detector
vent, with all other flows turned off.
Use nitrogen makeup gas (instead of helium) for greater
sensitivity.
Setting parameters for FID
WA R N I N G
Verify that a column is installed or the FID column fitting is
plugged before turning on the air or hydrogen. An explosion may
occur if air and hydrogen are allowed to leak into the oven.
To set the FID parameters:
1 Verify:
• Makeup gas is configured
• Installed jet type is correct for column type
2
302
Press [Front Det] or [Back Det].
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Detectors
10
3
Set the detector temperature. The temperature must be
greater than 150 °C for the flame to light.
4
Set the hydrogen flow rate, if desired, and press [Off/No].
5
Change the air flow rate, if desired, and press [Off/No].
6
If using a packed column, set the FID makeup gas to 0.0/Off.
7
If using a defined capillary column, set the makeup gas flow
or combined column plus makeup gas flow.
8
Scroll to Flame and press [On/Yes]. This turns on the air and
hydrogen and initiates the ignition sequence. The signal
typically increases to 5 to 20 pA after ignition.
Verify that the flame is lit by holding a cold, shiny surface,
such as a mirror or chrome- plated wrench, over the collector
exit. Steady condensation indicates that the flame is lit.
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About the TCD
The TCD compares the thermal conductivities of two gas
flows—pure carrier gas (the reference gas) and carrier gas plus
sample components (the column effluent).
This detector contains a filament that is heated electrically so
that it is hotter than the detector body. The filament
temperature is held constant while alternate streams of
reference gas and column effluent pass over it. When a sample
component appears in the effluent, the power required to keep
the filament temperature constant changes. The two gas
streams are switched over the filament five times per second
(hence the ticking sound) and the power differences are
measured and recorded.
When helium (or hydrogen) is used as carrier gas, the sample
causes the thermal conductivity to fall. If nitrogen is used, the
thermal conductivity usually goes up because most things are
more conductive than nitrogen.
Because the TCD does not destroy the sample during the
detection process, this detector can be connected in series to a
flame ionization detector or other detector.
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Column effluent
is forced away from
the filament. TCD
measures reference gas.
Advanced User Guide
10
Column effluent
is forced toward
the filament. TCD
measures peaks
(if present).
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TCD pneumatics
This is the pneumatics design of the TCD.
Makeup
Reference Gas
Vent
Valve
Frit
EPC Module
PS
Frit
Restrictor
Reference
switching valve
Valve
PS
Restrictor
Column
PS = Pressure Sensor
TCD carrier, reference, and makeup gas
Reference and makeup gas must be the same as the carrier gas,
and the gas type must be specified in both the inlet and detector
parameter lists.
When using packed columns, we recommend a small makeup
gas flow (2 to 3 mL/min) to get the best peak shapes.
Use the next figure to select a value for reference gas flow for
either capillary or packed columns. Any ratio within ±0.25 of
that in the figure is suitable.
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10
4.0
3.0
Ratio of reference flow to
column + makeup flow
2.0
1.0
0
10
20
30
40
50
60
Column + makeup flow, mL/min
TCD gas pressures
Choose a flow, find a pressure, set source pressure 10 psi
(70 kPa) higher.
4
Hydrogen
Helium
3
Reference gas flow, mL/min
Nitrogen
2
1
Pressure (psig)
(kPa)
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10
69
20
138
30
207
40
276
50
345
60
414
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20
16
Hydrogen
12
Makeup gas flow, mL/min
Helium
8
Nitrogen
4
Pressure (psig)
(kPa)
10
69
20
138
30
207
40
276
50
345
60
414
Selecting reference and makeup flows for the TCD
Table 67
Recommended flow rates and temperatures
Gas type
Flow range
Carrier gas
(hydrogen, helium, nitrogen)
Packed, 10 to 60 mL/min
Capillary, 1 to 5 mL/min
Reference
(same gas type as carrier)
15 to 60 mL/min
See the figures to select a value.
Capillary makeup
(same gas type as carrier)
5 to 15 mL/min—capillary columns
2 to 3 mL/min—packed columns
Detector temperature
<150 °C, cannot turn on filament
Detector temperature should be 30 °C to 50 °C greater than highest oven ramp
temperature.
Sample components with higher thermal conductivities than the
carrier gas produce negative peaks. For example, helium or
hydrogen form a negative peak with nitrogen or argon- methane
as the carrier gas.
Chemically active compounds reduce TCD filament life
The tungsten- rhenium TCD filament has been chemically
passivated to protect against oxygen damage. However,
chemically active compounds such as acids and halogenated
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Detectors
compounds may attack the filament. The immediate symptom is
a permanent change in detector sensitivity due to a change in
filament resistance.
If possible, such compounds should be avoided. If this is not
possible, the filament may have to be replaced frequently.
Changing the TCD polarity during a run
Negative polarity On inverts the peak so the integrator or
ChemStation can measure it. Negative polarity can be a run table
entry; see “Run Time Programming” on page 14.
Detecting hydrogen with the TCD using helium carrier gas
Hydrogen is the only element with thermal conductivity greater
than helium, and mixtures of small amounts of hydrogen (<20%)
in helium at moderate temperatures exhibit thermal
conductivities less than either component alone. If you are
analyzing for hydrogen with helium carrier gas, a hydrogen peak
may appear as positive, negative, or as a split peak.
There are two solutions to this problem:
• Use nitrogen or argon- methane as carrier gas. This
eliminates problems inherent with using helium as carrier,
but causes reduced sensitivity to components other than
hydrogen.
• Operate the detector at higher temperatures—from 200 °C to
300 °C.
You can find the correct detector operating temperature by
analyzing a known range of hydrogen concentrations, increasing
the operating temperature until the hydrogen peak exhibits
normal shape and is always in the same direction (negative
relative to normal response to air or propane) regardless of
concentration. This temperature also ensures high sensitivity
and linear dynamic range.
Because hydrogen peaks are negative, you must turn negative
polarity on at appropriate times so the peak appears positive.
Setting parameters for the TCD
1 Press [Front Det] or [Back Det].
2
Advanced User Guide
Set the detector temperature. Do not set higher than the
maximum temperature allowed for the column because part of
the column passes through the heated block and into the cell.
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10 Detectors
3
Verify that makeup gas type is the same as that plumbed to
your instrument (next to Makeup line in the parameter list).
Change the gas type, if necessary.
4
Set the reference gas flow rate.
5
If you are using packed columns, turn off the makeup gas (or
proceed to step 6 and enter 2 to 3 mL/min, see “TCD carrier,
reference, and makeup gas” on page 306) and proceed to
step 7
6
If you are using capillary columns:, choose a flow mode and set
the makeup gas flow or combined flow.
7
Turn on the filament. Allow about 30 minutes for thermal
stabilization. A longer period may be needed for the highest
sensitivity.
8
If necessary, turn Negative polarity [On/Yes] to invert
negative- going peaks. When a sample contains components
giving both positive- and negative- going peaks, Negative
polarity can be switched on and off during a run as a
timetable event.
Example: Packed mode (packed and large capillary columns)
Column flow is 15 to 60 mL/min. Set the reference flow to 1.5
times the sum of column flow + makeup flow.
Makeup gas is recommended with all capillary columns. It
allows the column to be inserted all the way into the detector
and withdrawn 1 mm. If makeup is not used, the column must
be no more than 3 mm above the ferrule. Minimum makeup flow
is 1 mL/min.
1/8-inch stainless steel column If column flow is 30 mL/min,
set the reference flow to 30 × 1.5 = 45 mL/min. Total detector
flow is 30 + 45 = 75 mL/min.
10 m × 0.53 mm column If column flow is 15 mL/min and
makeup flow = 2 mL/min, set the reference flow to 1.5 × (15 + 2)
= 25.5 mL/min. Total detector flow is 17 + 25.5 = 42.5 mL/min.
Example: Capillary mode (small capillary columns)
If combined column plus makeup flow is between 5 and
10 mL/min, set the reference flow at 3× the combined flow. For
a combined flow between 10 and 15 mL/min, use a multiplier of
2. This will bring the TCD within 25% of the maximum response.
For further optimization, adjust the reference flow.
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10
2 m × 0.2 mm capillary column If column flow is 0.75 mL/min,
the makeup must be at least 4.25 mL/min. Set it = 5. Reference
flow will then be 3 × 5.75 = 17.25 mL/min. Total detector flow =
5.75 + 17.25 = 22.5 mL/min.
25 m × 0.32 mm capillary column If column flow = 10 mL/min,
set makeup low to minimize sample dilution. Set it = 2 mL/min.
Reference flow will then be 12 × 2 = 24 mL/min. Total detector
flow = 12 + 24 = 36 mL/min.
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About the uECD
The micro- cell detector (uECD) contains a cell plated with 63Ni,
a radioactive isotope. The 63Ni releases β particles that collide
with carrier gas molecules to produce low- energy
electrons—each β particle produces approximately 100
electrons. The free electrons produce a small current—called the
reference or standing current—that is collected and measured
in a pulsed circuit.
When a sample component molecule comes into contact with
the free electrons, the electrons may be captured by the sample
molecules to create negatively charged ions. The voltage across
the cell electrodes is pulsed to collect the remaining free
electrons while the heavier ions are relatively unaffected and
swept out the vent with the carrier gas flow.
Cell current is measured and compared to a reference current.
The pulse rate is adjusted to maintain a constant cell current.
The more uncaptured electrons, the lower the pulse frequency
required to match the reference current. When a component
that captures electrons passes through the cell, the pulse rate
rises. This pulse rate is converted to a voltage and recorded.
uECD safety and regulatory information
The 63Ni isotope
The radioactive isotope used in the cell is 63Ni. It is plated onto
the inner surface of the cell body and is solid at temperatures
used in chromatography. Some other properties are listed
below.
Table 68
312
Properties of 63Ni
Property
Value
Half–life:
101.1 years
Emission:
65.87 keV max., beta radiation
Melting point:
1453 °C
Dimensions of the active part of the
uECD:
Inside diameter: 6 mm
Height: 4.2 mm
Total activity (uECD cell):
555 MBq (15 millicuries) maximum
Advanced User Guide
Detectors
10
ECD licenses
Customers in the United states can purchase a uECD under
either a General License or a Specific License. Customers
outside the United States should contact their local Agilent
sales office for information.
Specific License Specific License uECDs require you to obtain
a Materials License from the Nuclear Regulatory Commission
(NRC) or the local state agency, permitting you to possess the
amount and kind of radioisotope used in the detector. You can
typically ship, sell, or transfer the ECD to other Specific
Licensees. If the license permits, you may also open the uECD
for cleaning.
General License General License uECDs do not require a
Materials License. You become a General Licensee automatically
when you purchase a uECD directly from Agilent Technologies.
Some states may require that you register the uECD with a state
agency.
Certain restrictions apply to General Licenses:
1 Owners may not open the uECD cell.
2
Owners shall not modify the cell in any manner.
3
Owners shall not use any solvent, including water, to
internally clean the cell.
4
Owners shall not interfere with or attempt to defeat the
overheat circuitry that may be supplied with the uECD.
5
Owners shall not transfer the uECD to another person or
another location except as described in the applicable
Regulations.
6
Owners must perform a radioactive leak test at least every
6 months.
7
Owners must maintain records as required by your local
Agency (the NRC or, in certain states, a state agency).
8
Owners must notify the Agency in case of incidents or
failures that might lead to a hazardous condition.
Additional information is available in the publication
“Information for General Licensees,” part no. 5961- 5664.
uECD warnings
Although beta particles at this energy level have little
penetrating power —the surface layer of the skin or a few sheets
of paper will stop most of them—they may be hazardous if the
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10 Detectors
isotope is ingested or inhaled. For this reason the cell must be
handled with care: Radioactive leak tests must be performed at
the required intervals, the inlet and outlet fittings must be
capped when the detector is not in use, corrosive chemicals
must not be introduced into the detector, and the effluent from
the detector must be vented outside the laboratory
environment.
WA R N I N G
WA R N I N G
Materials that may react with the 63Ni source, either to form
volatile products or to cause physical degradation of the plated
film, must be avoided. These materials include oxidizing
compounds, acids, wet halogens, wet nitric acid, ammonium
hydroxide, hydrogen sulfide, PCBs, and carbon monoxide. This list
is not exhaustive but indicates the kinds of compounds that may
cause damage to 63Ni detectors.
In the extremely unlikely event that both the oven and the detector
heated zone should go into thermal runaway (maximum,
uncontrolled heating in excess of 400 °C) at the same time, and
that the detector remains exposed to this condition for more than
12 hours, take the following steps:
• After turning off the main power and allowing the
instrument to cool, cap the detector inlet and exhaust vent
openings. Wear disposable plastic gloves and observe normal
laboratory safety precautions.
• Return the cell for exchange, following directions included
with the License Verification Form (part no. 19233- 90750).
• Include a letter stating the condition of abuse.
It is unlikely, even in this very unusual situation, that
radioactive material will escape the cell. However, permanent
damage to the 63Ni plating within the cell is possible, and
therefore, the cell must be returned for exchange.
WA R N I N G
314
Do not use solvents to clean the uECD.
Advanced User Guide
Detectors
WA R N I N G
10
You may not open the uECD cell unless authorized to do so by your
local nuclear regulatory agency. Do not disturb the four
socket-head bolts. These hold the cell halves together. Removing
or disturbing them is a violation of the terms of the General
License and could create a safety hazard.
Safety precautions when handling uECDs
• Never eat, drink, or smoke when handling uECDs.
• Always wear safety glasses when working with or near open
uECDs.
• Wear protective clothing such as laboratory jackets, safety
glasses, and gloves, and follow good laboratory practices.
Wash hands thoroughly with a mild non- abrasive cleaner
after handling uECDs.
• Cap the inlet and outlet fittings when the uECD is not in use.
• Connect the uECD exhaust vent to a fume hood or vent it to
the outside. See the latest revision of title 10, Code of Federal
Regulations, part 20, (including appendix B) or the
applicable State regulation. For other countries, consult with
the appropriate agency for equivalent requirements.
Agilent Technologies recommends a vent line inside diameter
of 6 mm (1/4 inch) or greater. With a line of this diameter,
the length is not critical.
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10 Detectors
uECD gas flows
Anode purge and makeup gas
Restrictor
Frit
Vent
PS
63Ni
Valve
Restrictor
Capillary adapter
EPC Module
PS = Pressure Sensor
Column
uECD linearity
The uECD response factor versus concentration curve is linear
for four orders of magnitude or more (linear dynamic range =
104 or higher) for a broad range of compounds. You should still
run a calibration curve on your samples to find the limits of the
linear range for your materials.
uECD detector gas
The uECD operates with either nitrogen or argon/methane as
the makeup and anode gas. Purity is critical; gases must exceed
99.9995% purity.
Because of the high detector sensitivity, carrier and makeup gas
must be dry and oxygen- free. Moisture, chemical, and oxygen
traps in good condition should be installed in carrier and
makeup gas supply lines. Do not use plastic (including Teflon)
tubing, plastic- bodied traps, or O- ring seals.
uECD temperature
To prevent peak tailing and to keep the cell clean, the detector
temperature should be set higher than the highest oven
temperature used—the setpoint should be based on the elution
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10
temperature of the last compound. If you operate at excessively
high temperatures, your results will not necessarily improve
and you may increase sample and column decomposition.
uECD analog output
If you intend to use the analog output from the uECD, you must
set the output Range to 10.
1 Press [Analog Out 1] or [Analog Out 2].
2 Scroll to Range.
3 Type 10 and press [Enter].
Recommended starting conditions for new uECD methods
Use the following information when selecting temperatures and
flows. Maximum source pressure must not exceed 100 psi. Use
the maximum source pressure to achieve maximum makeup
flow rate.
Table 69
Starting values
Gas
Carrier gas
Packed columns
(nitrogen or argon-methane)
Capillary columns
(hydrogen, nitrogen, or
argon-methane)
Capillary makeup
(nitrogen or argon-methane)
Recommended flow range
30 to 60 mL/min
0.1 to 20 mL/min,
depending on diameter
10 to 150 mL/min
(30 to 60 mL/min typical)
Temperature
250 °C to 400 °C
Detector temperature is typically set 25 °C greater than the highest oven ramp
temperature.
uECD makeup gas notes
If the carrier gas type is different from the makeup gas type, the
makeup gas flow rate must be at least three times the carrier
gas flow rate.
uECD sensitivity can be increased by reducing the makeup gas
flow rate.
uECD chromatographic speed (for fast peaks) can be increased
by increasing the makeup gas flow rate.
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uECD temperature programming
The uECD is flow sensitive. If you are using temperature
programming, in which the column flow resistance changes
with temperature, set up the instrument as follows:
• Set the carrier gas in the Constant flow mode. Set detector
makeup gas to Constant makeup.
• If you choose to work in the constant pressure mode, the
makeup gas should be set in the Column +makeup=constant
mode.
Setting parameters for the uECD
Verify that your detector gases are connected, a column is
properly installed, and the system is free of leaks. Set the oven
temperature and the inlet temperature and flow. Make sure your
carrier gas type is the same as that plumbed to your GC.
1 Press [Front Det] or [Back Det].
2
Set the detector temperature. To keep the uECD cell clean,
this temperature must be higher than the oven temperature.
3
Verify that the makeup gas type is the same as that plumbed
to your instrument. The gas type is in parentheses next to
the Makeup line on the parameter list. Change the gas type, if
necessary.
4
Enter a value for the makeup gas flow.
• If you are using packed columns, turn off the makeup gas.
• If your capillary column is defined, choose a flow mode and
set the makeup or combined gas flow.
• If your capillary column is not defined, only constant
makeup flow is available. Enter a makeup gas flow.
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About the NPD
New NPD features and changes
The NPD firmware in this GC (A.01.08 or higher) is
considerably different from that in earlier versions and from the
6890 firmware. Major changes are:
• Equilibration time parameter has been removed.
• Adjust Offset feature has been changed.
• Auto Adjust on/off has been added.
• Dry Mode has been added.
• Blos/ceramic bead selector has been added.
We strongly recommend that you allow the firmware to perform
Auto Adjust and set the Bead Voltage.
NPD software requirements
This discussion assumes that the following firmware/software
is installed:
Table 70
Software requirements
Product
Software/firmware revision
7890A GC
A.01.08 or higher
Agilent GC ChemStation
B.04.01 or higher
Agilent MSD ChemStation
G1701EA or higher
Agilent EZ Chrom Elite
3.3.2 or higher
Software/firmware with numbers less than shown in the table
can cause reduced bead lifetime. See the Agilent web site
(www.agilent.com) for firmware and software updates.
NPD flows and general information
The NPD passes sample and carrier through a hydrogen/air plasma.
A heated ceramic or glass source, called the bead, is just above the jet.
The low hydrogen/air ratio cannot sustain a flame, minimizing
hydrocarbon ionization, while the alkali ions on the bead surface
facilitate ionization of nitrogen- or phosphorus- organic compounds.
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The output current is proportional to the number of ions collected. It
is sensed by an electrometer, converted to digital form, and sent to an
output device.
H2
Makeup
Frit
Frit
Valve
Valve
Air
EPC Module
Frit
Valve
Vent
PS
PS
Restrictor
Electrically
heated bead
Restrictor
PS
Restrictor
PS = Pressure Sensor
Column
NPD flow, temperature, and bead recommendations
Table 71
General operating values
Gas or Setting
Recommendation
Carrier gas (helium, hydrogen, nitrogen) Capillary, choose optimum flow
based on column dimensions.
Detector gases
320
Hydrogen
Ceramic bead
2 to 5 mL/min
Blos bead
1 to 3 mL/min
Air
Ceramic bead
60 mL/min
Blos bead
120 mL/min
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Table 71
General operating values (continued)
Gas or Setting
Capillary makeup (helium, nitrogen)
Recommendation
Ceramic bead
Nitrogen: 5 to 10 mL/min
Helium: less than 5 mL/min
Blos bead
1 to 20 mL/min
Temperature
Default is 250 °C; operating range is 150 °C to 400 °C.
• <150 °C, the Adjust offset process will not start.
• 325 to 335 °C is recommended.
• Detector temperature should be greater than the highest oven temperature.
With higher detector temperatures, less bead heating voltage is required.
Adjust offset
Default is 30 pA, suggested operating range is 20 to 40 pA, and allowable range
is 0 to 99.9 pA.
• ≥50 pA increases sensitivity but reduces bead life.
• Lower settings reduce sensitivity and increase bead life, but settings too low
will result in solvent quenching.
• The time required for Adjust offset depends on the bead type and condition.
Bead voltage
Ceramic bead. Range is 0 to 4.095 V.
Blos bead. Range is 0.5 to 1.1 V.
• Use Auto Adjust On, Dry Bead, and let the GC set the Bead Voltage for you.
Source gas pressures
Choose a flow, find a pressure, and set source pressure 10 psi
(70 kPa) higher.
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150
Air
100
Flow, mL/min
Helium
50
Nitrogen
Pressure (psig)
(kPa)
5
10
69
20
138
30
207
40
276
50
345
60
414
70
483
4
Hydrogen
3
Flow, mL/min
2
1
Pressure (psig)
(kPa)
4
28
8
55
12
83
16
110
20
138
Temperature programming
The NPD is flow sensitive. If you are using temperature
programming, in which the column flow resistance changes
with temperature, set up the instrument as follows:
• Set the carrier gas in the Constant flow mode. Set detector
makeup gas to Constant makeup.
• If you choose to work in the constant pressure mode, the
makeup gas should be set in the Column +makeup=constant
mode.
NPD required gas purity
Because of its high sensitivity, the NPD requires very pure (at
least 99.9995%) gases. We strongly recommend that moisture
and organics traps be used on the carrier gas and all detector
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gases, including the detector hydrogen, air, and makeup gases.
Do not use plastic (including Teflon) tubing, plastic- bodied
traps, or O- ring seals.
Setting parameters for the NPD
Before operating the NPD, make sure that detector gases are
connected, a column is installed, and the system is free of leaks.
Set the oven temperature, inlet temperature, and column flow.
WA R N I N G
Make sure that a column is installed or the NPD column fitting is
plugged before turning on the air or hydrogen. An explosion may
occur if air and hydrogen are allowed to leak into the oven.
1 Select the bead (white ceramic, black ceramic, Blos).
2
Select the jet.
3
Install bead and jet as required. (See the Maintenance
Manual for details.)
4
Press [Config][Front Det] or [Config][Back Det].
5
If you are using makeup gas, verify that the configured
makeup gas type is the same as that plumbed to your
instrument. Change the gas type, if necessary. Nitrogen is
recommended.
6
If the displayed Bead Type is incorrect, set the Bead Type
using the [Mode/Type] key.
7
Set Auto Adjust (On recommended).
8
Set Dry Bead (On recommended).
9
Press [Front Det] or [Back Det].
10 Set the detector temperature. The recommended range is
325 to 335 °C.
11 Enter a hydrogen flow (3.0 mL/min is recommended). Turn
the flow On.
12 Enter an air flow (60 is recommended for ceramic beads, 120
for Blos beads). Turn the flow On.
a If you are using packed columns, turn off makeup gas and
proceed to step 13.
b If your capillary column is defined, choose a flow mode
and set the makeup gas flow. For a column in the constant
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flow mode, choose Constant makeup. For a column in the
constant pressure mode, choose Column +makeup=constant.
c If your column is not defined, enter a makeup gas flow.
Only constant flow is available.
13 Monitor the offset adjustment process.
a If Auto Adjust is On, the adjust offset process starts
automatically when the detector reaches setpoint. If Auto
Adjust is Off, the Bead Voltage will gradually go to the last
setpoint after the bead reaches setpoint temperature and
the Dry Bead time has elapsed.
b If you need to set a new target offset, enter an Adjust offset
value. Adjust offset starts when the detector reaches
setpoint.
c If Auto Adjust is Off, you can manually start the Adjust
offset process by scrolling to Adjust offset, then pressing
[On/Yes].
d If your standard operating procedures require that you set
the bead voltage directly, see “Setting NPD bead voltage
manually (optional)” on page 329.
Selecting an NPD bead type
Three beads are available:
Table 72
NPD beads
Bead type
Part number
Advantages
Disadvantages
White ceramic
G1534-60570
Standard
Phosphorus tails
Black ceramic
5183-2007
Durable, no
phosphorus
tailing
Lower nitrogen
sensitivity,
about 40%
Blos bead
G3434-60806
Moisture
resistant, long life
Ceramic beads
324
Blos bead
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Changing from a ceramic bead to a Blos bead
CAUTION
The Blos bead is more delicate than the ceramic beads, and may be
distorted during shipping. Before installing a Blos bead, verify that it
is centered and adjust it if necessary.
When you turn the NPD off, the GC remembers the bead voltage
used and applies that voltage when the detector is turned back
on. If you have changed from a ceramic bead to a Blos bead, this
voltage will be too high and may damage the new bead.
To avoid this, reduce the voltage to the ceramic bead to 0.5 V
before turning the detector off. When it restarts, the lower
voltage will be applied.
Selecting an NPD jet
Open the oven door and locate the column connection fitting at
the base of the detector. It will look like either a capillary
optimized fitting or an adaptable fitting.
Adaptable fitting
Capillary optimized fitting
Detector fitting
Adapter
• If you have an application that tends to clog the jet, select a
jet with a wider tip id.
• When using packed columns in high column- bleed
applications, the jet tends to clog with silicon dioxide.
For capillary optimized fittings, select one of the following from
Table 73.
Table 73
Jets for capillary optimized fittings
Figure 3 ID
Jet type
Part number
Jet tip id
Length
1
Capillary with extended jet
(recommended)
G1534-80580
0.29 mm (0.011 inch)
51.5 mm
2
Capillary
G1531-80560
0.29 mm (0.011 inch)
43 mm
3
High-temperature
G1531-80620
0.47 mm (0.018 inch)
43 mm
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51.5 mm
1
43 mm
2
43 mm
1
3
Figure 1
2
3
Capillary optimized NPD jets
For the adjustable NPD, select one of the following from
Table 74.
Table 74
Jets for adaptable fittings
Figure 4 ID
Jet type
Part number
Jet tip id
Length
1
Capillary with extended jet
(recommended)
G1534-80590
0.29 mm (0.11 inch)
70.5 mm
2
Capillary
19244-80560
0.29 mm (0.011 inch)
61.5 mm
3
Capillary, high-temperature
19244-80620
0.47 mm (0.018 inch)
61.5 mm
4
Packed
18710-20119
0.46 mm (0.018 inch)
63.6 mm
70.5 mm
1
61.5 mm
2
61.5 mm
3
1
63.6 mm
2
3
4
4
Figure 2
Adaptable NPD jets
To configure the NPD
In addition to the Ignore Ready and Makeup gas type, the NPD
requires the following configuration settings. Scroll to each and
enable/disable using [On/Yes] or [Off/No].
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Auto Adjust Bead Recommended On. When On, the automatic
adjust offset process starts when the bead reaches the
temperature setpoint after having been turned off or cooled
below 150 °C. Auto adjust starts after Dry Bead hold time, if
enabled. Auto Adjust Bead uses the adjust offset feature to
protect the bead—especially new beads—by making sure that the
desired offset is obtained with the lowest possible bead voltage.
When Off, the bead voltage will rise as soon as the Dry Bead
time elapses, or as soon as the temperature setpoint is reached
if Dry Bead is off.
Dry Bead Recommended On. When On, the bead temperature
holds at 150 °C for 5 minutes before continuing to the setpoint.
This allows any condensation to evaporate and be swept out of
the detector.
Blos Bead If using a Blos bead, set to On. For ceramic beads, set
to Off. The Blos Bead On setting restricts the allowable bead
voltage to the range appropriate for this bead.
Maximum Bead Voltage Display only. Shows the current
maximum bead voltage for the configured bead type (4.095 V for
ceramic beads, 1.1 V for the Blos bead).
Automatically adjusting NPD bead voltage
Agilent recommends using the Adjust offset feature to
automatically determine the lowest bead voltage needed to give
the desired response.
When the detector is turned on, the temperature rises at a
controlled rate.
• If Dry Bead is On, temperature holds at 150 °C for 5 minutes to
drive off moisture, then continues to the setpoint.
• If Dry Bead is Off, the temperature rises directly to the
setpoint.
When the temperature reaches the setpoint, the Bead Voltage
gradually rises until it produces the desired output.
Adjust offset
When you enter a value here, or press [On/Yes] to use the stored
value, detector gas flows turn on, the bead heats, and the bead
voltage adjusts until Output is stable and equal to the entered
value. There are five stages of Adjust offset.
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Detector off When the detector is off, Adjust offset and Bead
voltage are Off and initial Output is displayed.
Detector on—detector temperature less than 150 °C. When you
enter an Adjust offset value or press [On], detector gases turn on
and the display blinks the Temp not ready message.
Detector on—waiting for oven and/or detector to reach temperature
setpoint and equilibrium. If the oven or detector is not at
setpoint, the display continues to blink the Temp not ready
message.
Detector on—Dry Bead On If Dry Bead is On, the temperature rise
holds at 150 °C for 5 minutes to remove moisture, then
continues to the setpoint.
Detector on—during adjust offset. When the detector and oven
temperatures reach setpoint and equilibrate, the Adjust offset
process begins. The bead voltage is slowly increased until the
output is close to the Adjust offset value. The display blinks
Detector Slewing.
Detector on and ready. When the Adjust offset value is reached,
the Adjust offset line reads Done and displays the offset target
setpoint. Your detector is on and ready. The display shows the
actual Bead voltage.
Setting NPD adjust offset on the clock table
You can use the Clock table feature to begin Adjust offset at a
specified time.
Aborting NPD adjust offset
Press [Delete] with the cursor on the Adjust offset line. This
cancels the adjustment without turning off the detector gases
and bead voltage.
Extending the NPD bead life
These actions, together with the automated heatup and adjust
procedures, can extend ceramic bead life considerably.
• Use the lowest practical Adjust offset value. This will result in
a lower Bead Voltage during operation.
• Run clean samples.
• Turn the bead off when not in use.
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• Keep the detector temperature high (320 to 335 °C).
• Turn the hydrogen flow off during solvent peaks and
between runs.
Turning hydrogen off during a solvent peak
When using the NPD, the baseline shifts after a solvent peak and
can take some time to stabilize, especially with chlorinated
solvents. To minimize this effect, turn off the hydrogen flow
during the solvent peak and turn it back on after the solvent
elutes. With this technique, the baseline recovers to its original
value in less than 30 seconds. This also extends the life of the
bead. The hydrogen can be turned on and off automatically as
part of a Run Table. See “Run Time Programming” on page 14.
Turning hydrogen off between runs
To extend bead life, turn off the hydrogen flow between runs.
Leave all other flows and the detector temperature on. Turn on
the hydrogen flow for the next run; the bead will ignite almost
immediately. The process can be automated with Run Table
entries.
Turning off the detector
CAUTION
If you turn Adjust offset [Off] at any time, the bead voltage,
hydrogen, and air flows all turn off.
Setting the initial bead voltage for new beads
Before you turn on the bead for the first time, manually set its
voltage to a safe value so that the new bead is not destroyed.
1 Make sure Adjust Offset is turned Off.
2
After the temperature stabilizes at setpoint, set the initial
Bead Voltage, depending on bead type:
• Blos bead: 0.0 V to 0.5 V
• Ceramic bead (white or black): 0.0 V to 2.0 V
Setting NPD bead voltage manually (optional)
Bead voltage shows the voltage used to heat the bead. It can be a
value derived from the Adjust offset value, or can be entered as a
setpoint. Entering a setpoint causes the voltage to change at
13 mV/second until it reaches the setpoint provided that
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• the detector is at the temperature setpoint
• temperature is at least 150 °C
• gas flows are on
• Dry Bead time, if On, has elapsed
Bead voltage is also useful for small adjustments between runs. If
you observe a baseline drift, you can enter a small, one- time
change to compensate for the drift.
If you are not using the recommended Adjust offset process,
note that large voltage jumps reduce bead life. Use increments
no greater than 0.05 V, spaced 10 seconds apart, until you reach
the desired offset.
New beads
After a new bead reaches the initial voltage, begin to increase
the voltage value in 0.05 V increments until the bead ignites.
Wait about 10 seconds between each voltage adjustment.
Monitor the detector output. When the bead ignites, the output
will rise suddenly, then decrease towards a more stable value. It
is best to allow the NPD to remain in this state without further
adjustment for about 24 hours. Then you may adjust the bead
voltage in small increments (0.05 to 0.1 V) until reaching the
desired offset. With a clean environment, clean gas supplies,
and low bleed column, a typical offset may decrease 6- 12 pA
during a 24 hour period.
Typical voltages for new ceramic beads range from 2.5 to
3.7 volts. Higher values reduce bead life.
Typical voltages for new Blos beads range from 0.5 to 1.0 V.
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About the FPD
The sample burns in a hydrogen- rich flame, where some species
are reduced and excited. The gas flow moves the excited species
to a cooler emission zone above the flame where they decay and
emit light. A narrow bandpass filter selects light unique to one
species, while a shield prevents intense carbon emission from
reaching the photomultiplier tube (PMT).
The light strikes a photosensitive surface in the PMT where a
light photon knocks loose an electron. The electron is amplified
inside the PMT for an overall gain of up to a million.
H2
Makeup
Frit
Frit
Valve
Valve
Air
EPC Module
Frit
Vent
Valve
Emission Zone
PS
PS
PS
Restrictor
Wavelength filter
Window
Restrictor
PS = Pressure Sensor
Restrictor
Column
The current from the PMT is amplified and digitized by the FPD
electronics board. The signal is available either as a digital
signal on the communications output or as a voltage signal on
the analog output.
The FPD should not be stored at temperatures above 50 °C,
based on the original manufacturer’s specifications for the PMT.
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FPD linearity
Several mechanisms produce sulfur emission. The excited
species is diatomic, so that emission intensity is approximately
proportional to the square of the sulfur atom concentration.
The excited species in the phosphorus mode is monatomic,
leading to a linear relationship between emission intensity and
atom concentration.
FPD Lit Offset
The default Lit Offset is 2.0 pA.
Starting Up and Shutting Down the FPD
The FPD creates a great deal of water vapor when the flame is
on. This could condense in the vent tube on top of the detector
and drop onto the flame, possibly extinguishing it. To avoid this,
turn the heaters on, wait 20 minutes for the vent to heat up, and
then ignite the flame. Water vapor will now make it over the top
of the vent tube before condensing.
For similar reasons, extinguish the flame before turning the
heaters off.
FPD photomultiplier protection
The PMT is extremely sensitive to light. Always turn the PMT
voltage off (which turns off the high voltage to the PMT) before
removing the PMT housing or opening the emissions chamber.
Failing to do this can destroy the PMT.
Even with the PMT voltage off, protect the PMT from room light.
Cap the housing when removed, place it end down to exclude
light, reduce room light level before exposing the PMT, and so
on. A brief exposure (always with the PMT voltage turned off)
will not damage it but prolonged exposure will cause a gradual
loss of sensitivity.
FPD optical filters
The filters are marked on the edge with the transmission
wavelength. Each filter has a small arrow on its side which must
point toward the PMT when installed.
The sulfur filter is silvery on both sides and transmits at
393 nanometers.
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The phosphorus filter is yellow/green and transmits at
525 nanometers.
Inlet liners for use with the FPD
Compounds containing sulfur may adsorb on an inlet liner and
degrade the GC’s performance. Use deactivated, clean liners or
a cool on- column inlet, which injects directly onto the column.
For best results with splitless injection, use liner 5181- 3316.
FPD temperature considerations
The minimum detector temperature to prevent water
condensation is 120 °C. We recommend a temperature that is
25 °C higher than the highest column temperature, but no
higher than 250 °C.
FPD gas purity
High- purity gases have a lower sulfur content. Standard purity
gases have a higher sulfur content which impairs sulfur
detection in the compound being studied. Instrument or
Chromatographic grades work well.
Agilent recommends using helium carrier, nitrogen makeup gas,
and air with 99.9995% purity or better. Use carbon, oxygen, and
moisture traps. Select traps to remove sulfur compounds from
detector air and nitrogen gases. A helium getter is also
recommended.
FPD gas flows
Table 75 gives the flows for the maximum sensitivity FPD flame,
which is hydrogen- rich and oxygen- poor.
Table 75
Recommended flows
Sulfur mode flows,
mL/min
Phosphorus mode
flows, mL/min
Carrier (hydrogen, helium, nitrogen, argon)
Packed columns
10 to 60
10 to 60
Capillary columns
1 to 5
1 to 5
50
75
Detector gases
Hydrogen
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Table 75
Recommended flows (continued)
Sulfur mode flows,
mL/min
Phosphorus mode
flows, mL/min
Air
60
100
Carrier + makeup
60
60
Helium, either as carrier or makeup gas, may cool the detector
gases below the ignition temperature. We recommend using
nitrogen rather than helium.
Lighting the FPD flame
Before trying to light the flame, have the detector at operating
temperature. Removing the condensate tubing may help, but be
sure to replace it before making runs.
It is difficult to light the flame with the flows shown in Table 75,
particularly in the sulfur mode. If the flame will not light with
the sulfur mode flows shown, change to the phosphorus mode
flows. After ignition, gradually reduce the flows to the sulfur
values. Some experimentation will be needed.
When either of the flame ignition methods in this section is
used, the FPD automatically performs this sequence:
1 Turns all detector gases—air, hydrogen, makeup—off. Carrier
remains on.
2
Sets air flow to 200 mL/min.
3
Turns the glow plug ignitor on.
4
Ramps the hydrogen flow from 10 to 70 mL/min.
5
Resets the air flow to the air flow setpoint.
6
Resets the hydrogen flow to the hydrogen flow setpoint.
7
Turns the makeup gas on.
8
Compares the signal change with the Lit offset value. If the
change is greater than Lit offset, declares the flame on (lit). If
it is less, declares the flame off (not lit).
For this process to work, there must be enough air pressure to
the pneumatics module to provide 200 mL/min flow. We
recommend a supply pressure of 90 psi.
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Manual ignition
1 Press [Front Det] or [Back Det].
2
Scroll to Flame. Press [On/Yes]. The flame ignition sequence
begins.
Automatic ignition
If the FPD output with the flame on falls below the flame- off
output plus the Lit offset value, this is interpreted as a flame- out
condition. The FPD runs the flame ignition sequence to relight
the flame. If this fails, it runs the sequence again. If the second
attempt also fails, the detector shuts down all functions except
temperature and makeup gas flow.
Setting parameters for the FPD
WA R N I N G
Verify that a column is installed or the FPD fitting is plugged
before turning on the air or hydrogen. An explosion may occur if
air and hydrogen are allowed to leak into the oven.
1 Press [Front det] or [Back det].
2
Set the detector temperature. It must be greater than 120 °C
for the flame to light.
3
Change the hydrogen flow rate, if desired. Press [Off/No].
4
Change the air flow rate, if desired. Press [Off/No].
5
If you are using packed columns, turn off the makeup gas
and proceed to step 7.
6
If you are using capillary columns:
a Verify that makeup gas type is the same as that plumbed
to your instrument (next to Makeup in the parameter list).
Change the gas type, if necessary.
b If your capillary column is defined, choose a flow mode
and set the makeup gas flow or combined flow.
c If your capillary column is not defined, enter a makeup
gas flow. Only constant flow is available.
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Scroll to Flame and press [On/Yes]. This turns on the air and
hydrogen and initiates the ignition sequence.
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10 Detectors
On ignition, the signal increases. Typical levels are 4 to 40 pA
in sulfur mode, 10 to 70 pA in phosphorus mode. Verify that
the flame is lit by holding a cold, shiny surface, such as a
mirror or chrome- plated wrench, over the vent exit. Steady
condensation indicates that the flame is lit.
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Valves
About Valves 338
The Valve Box 339
Heating the valves 339
Valve temperature programming 339
Configuring an Aux thermal zone 340
Valve Control 341
The valve drivers 341
The internal valve drivers 341
The external valve drivers 342
Valve Types 343
Configuring a Valve 344
Controlling a Valve 345
From the keyboard 345
From the run or clock time tables 345
Simple valve: column selection 345
Gas sampling valve 346
Multiposition stream selection valve with sampling valve 347
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About Valves
Valves may be used to alter the usual inlet/column/detector
flow path in the GC. Sampling valves can replace the inlet,
switching valves can select columns, multiposition valves, used
in conjunction with sampling valves, can perform the same
functions for sample streams that an ALS performs for liquid
samples.
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The Valve Box
The GC holds up to four valves in a heated valve box on top of
the oven.
The valve box is the preferred location for valves because it is a
stable temperature zone, isolated from the column oven.
Back of chromatograph
Valve heater
blocks
Valve box,
cover removed
Figure 3
Diagram of valve locations on GC
Valves may also be mounted inside the column oven.
Heating the valves
The valve box contains two heated blocks, each with two valve
mounting locations (shaded in Figure 3).a The middle hole on
each block is used to pass tubing into the column oven.
If two valves are used, mount them on the same block. This
allows them to be heated using only one control channel (Aux
Temp 1 or Aux Temp 2, depending on how the heaters are wired).
With more than two valves, both channels must be used for
heating the two blocks. Set them at the same temperature.
Valve temperature programming
Most valve applications are isothermal; however, you can define
three temperature ramps if desired. Press [Aux Temp #], then [1]
or [2]. Program this ramp the same as an oven ramp. Refer to
“Setting the oven parameters for ramped temperature” on
page 282 for more information.
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Configuring an Aux thermal zone
To configure a thermal Aux zone (1 or 2), press [Config][Aux Temp
#], then [1] or [2]. Press [Mode/Type], then select the type of
device to be controlled. Press [Enter].
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Valve Control
Valves can be controlled manually from the keyboard or as part
of a clock or run time program. Note that only sampling valves
automatically reset at the end of a run. Other valve types remain
at the new position until activated again. For other valve types,
you must include any desired resets in the program.
The valve drivers
A valve driver is the software and circuitry in the GC that
controls a valve or related function. There are eight drivers
known as Valve 1 through Valve 8.
Table 76
Valve drivers
Valve number
Type
Volts
Power or current
Use
1, 2, 3, and 4
Current source
24 VDC
13 watts
Pneumatic valve
control
5 and 6
Current source
24 VDC
100 mA
Relays and low-power
devices
7 and 8
Contact closure
48 VDC or 48 VAC
RMS
Control an external
current source
The internal valve drivers
Valve drivers 1 through 4 are usually used to control
pneumatically operated valves mounted in the valve box. The
wiring for these appears at a set of connectors inside the right
cover of the GC.
Pneumatically driven valves are controlled by solenoids
mounted near the connectors that control the flow of air to the
valve actuators.
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Keyboard
Connector V1
or
Connector V2
Run table
Internal valve drivers
(1 through 4)
Connector V3
or
Connector V4
Clock table
There is no direct relationship between the location of a valve in
the valve box and the driver that controls it. This depends on
how the solenoids are wired and the actuators are plumbed.
Manual valves must be switch by hand, and are heated or
unheated.
The external valve drivers
Valve drivers 5 and 6 control a current that may be used to drive
a relay or other low- power device. Valve drivers 7 and 8 switch
a current from an external source. Electrical details are in
Table 76 on page 341.
These drivers, particularly Valve 7 and 8, may be used to control
a motor driven multiposition valve for stream selection.
All four of these drivers appear on the External Event
connector on the back of the GC.
Keyboard
Valve 5 (pin 1) and
ground (pin 3 or 4)
or
Run table
342
External valve drivers
(5 through 8)
Valve 6 (pin 2) and
ground (pin 3 or 4)
or
Valve 7 (pin 5
and pin 6)
Clock table
Valve 8 (pin 7
and pin 8)
Advanced User Guide
Valves
11
Valve Types
There possible valve types are:
Sampling A two- position (load and inject) valve. In load
position, an external sample stream flows through an attached
(gas sampling) or internal (liquid sampling) loop and out to
waste. In inject position, the filled sampling loop is inserted into
the carrier gas stream. When the valve switches from Load to
Inject, it starts a run if one is not already in progress. See the
example on page 346.
Switching A two- position valve with four, six, or more ports.
These are general- purpose valves used for such tasks as column
selection, column isolation, and many others. For an example of
valve control, see page 347.
Multiposition Also called a stream selection valve. It is usually
used to select one from a number of gas streams and feed it to a
sampling valve for analysis. It has a special actuator that
advances the valve one position each time it is activated, or it
may be motor driven. An example that combines a stream
selection valve with a gas sampling valve is on page 347.
Other
Could be anything.
Not installed
Advanced User Guide
Self- explanatory.
343
11 Valves
Configuring a Valve
1 Press [Config]. Scroll to Valve #.
344
2
Enter the valve number and press [Enter]. The current valve
type is displayed.
3
To change the valve type, press [Mode/Type], select the new
valve type, and press [Enter].
Advanced User Guide
11
Valves
Controlling a Valve
From the keyboard
Valves (except multiposition valves) have two positions
controlled by the [On] and [Off] keys. The keyboard commands
for two- position valves are:
[Valve #] <scroll to the valve> [On]
Rotates valve to one stop
and
[Valve #] <scroll to the valve> [Off]
stop
Rotates valve to the other
From the run or clock time tables
The Valve On and Valve Off commands can be run time or clock
time programmed. See “Run Time Programming” on page 14
and “Clock Time Programming” on page 17.
If a valve is rotated by a run time program, it is not
automatically returned to its initial position at the end of the
run. You must program this reset operation yourself.
Simple valve: column selection
This is the plumbing for a single valve, configured as a switching
valve, that selects one of two columns for analysis. It has no
configuration parameters.
Front column
From inlet or
sampling valve
To detector
ON
OFF
Back column
The column is selected by pressing:
[Valve #] <scroll to valve #> [On] (for the front column) or [Off]
(for the back column).
Advanced User Guide
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11 Valves
Use a run table entry to ensure that the valve is in the Off state
between runs.
Gas sampling valve
If a valve is configured as a gas sampling valve, it starts a run
automatically when it is switched to the Inject position. This
can be done with a keyboard command or by a subsequence or
clock table entry. You may have two gas sampling valves
installed.
To column
Carrier in
LOAD position
INJECT position
Loop
Sample in
Sample out
Load position The loop is flushed with a stream of the sample
gas. The column is flushed with carrier gas.
Inject position The filled loop is inserted into the carrier gas
stream. The sample is flushed onto the column. The run starts
automatically.
Carrier gas may be provided by an (optional) auxiliary gas
channel. To do this, configure the column and specify an Aux #
channel as the inlet. The channel then becomes programmable
with four operating modes.
Sampling valves have two positions:
Load position The loop (external for gas sampling, internal for
liquid sampling) is flushed with a stream of the sample. The
column is flushed with carrier gas.
Inject position The filled loop is inserted into the carrier gas
stream. The sample is flushed onto the column. The run starts
automatically.
The sampling valve control parameters are:
346
Advanced User Guide
Valves
11
Load time Time in minutes that the valve remains in the Load
position before becoming ready.
Inject time Time in minutes that the valve remains in the Inject
position before returning to the Load position.
The sampling valve cycle is:
1 The sampling valve rotates to the Load position. Load time
begins. Valve is not ready.
2
Load time ends. The valve becomes ready.
3
If everything else is ready, the GC becomes ready. If anything
is not ready:
• If you are using Clock Table or sequence control, the GC
waits until everything is ready, then executes the valve
inject command.
• If you are not using Clock Table or sequence control, the
valve injection can be made at any time from the
keyboard.
4
The sampling valve rotates (keyboard command or sequence
control) to the Inject position. Inject time begins. The run
begins.
5
Inject time ends. Return to step 1.
Multiposition stream selection valve with sampling valve
Several manufacturers provide multiposition stream selection
valves that can be driven by valve drivers 1 through 4. Only one
multiposition valve can be configured.
If a valve is configured as a multiposition valve and has a BCD
position output connected to the GC, the valve position can be
selected directly.
Advanced User Guide
347
11 Valves
Sampling valve
Multiposition stream
selection valve
Sample streams in
Selected stream out
If the GC has one valve configured as a multiposition valve and
another configured as a gas or liquid sampling valve, it assumes
that they are to be used in series. This “double configuration”
can be used to replace an automatic liquid sampler and sample
tray in an analytical sequence. The multiposition valve becomes
the sample tray; the sampling valve becomes the injector.
Two configuration parameters provide mechanical and
electrical compatibility with most multiposition valve actuators.
Switching time In seconds, is a delay between successive
actuator movements. It allows time for the actuator mechanism
to prepare for the next movement.
Invert BCD Complements the BCD input; 1’s become 0’s and 0’s
become 1’s. This accommodates coding convention differences
among manufacturers.
348
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Agilent 7890A Gas Chromatograph
Advanced User Guide
12
7683B Sampler
About the 7683B Sampler 350
Setting Parameters for the ALS 351
Solvent Saver 352
Sample tray setpoints 353
Storing setpoints 353
Agilent Technologies
349
12 7683B Sampler
About the 7683B Sampler
The 7683B Automatic Liquid Sampler (ALS) is controlled by a
sequence that specifies what samples are to be analyzed, where
the sample vials are located in the sampler tray (if used), what
methods are to be used for each sample, and possibly what to do
after the last sample to clean out the column. See “Creating
Sequences” on page 111 for more information on sequences.
Hardware
Consult the 7683B for all mechanical details, such as
installing/removing the tray, injectors, bar code reader,
syringes, and so on. Follow the instructions for the 6890N GC.
Software
The new 7890A parameters are described in this chapter.
Follow these instructions for all non- mechanical operations.
350
Advanced User Guide
7683B Sampler
12
Setting Parameters for the ALS
Pressing either of the injector keys allows you to edit injector
control setpoints, such as injection volumes, sample and solvent
washes, etc.
To edit the injector setpoints:
1 Press [Front Injector] or [Back Injector].
2
Scroll to the desired setpoint.
3
Enter a setpoint value, or turn the setpoint On or Off.
4
Press [Mode/Type] to make selections for syringe size and
syringe plunger speed.
Injection volume Sample volume to be injected. Press
[Mode/Type] to select. The available volumes depend on the
syringe size configured.
• The selections represent 2%, 10%, 20%, 30%, 40%, and 50% of
syringe size.
• Turn the injection volume Off to disable the injector.
Viscosity delay (0-7 seconds) How long the plunger pauses at
the top of the pump and injection strokes. For viscous samples,
the pause allows the sample to flow into the vacuum created in
the syringe.
Inject Dispense Speed The speed of the syringe plunger during
injection. Enables you to reduce the average speed of the
plunger. Press [Mode/Type] to see the choices. The plunger speed
during the pump and waste dispensing does not change.
Sample pumps (0-15) How many times the syringe plunger is
moved up and down with the needle in the sample to expel air
bubbles and improve reproducibility.
Sample washes (0-15) How many times the syringe is rinsed
with sample before the injection. The wash volume is set by the
Solvent Saver setting.
Solvent A post washes (0-15) How many times the syringe is
washed with solvent A after injection.
Solvent A pre washes (0-15) How many times the syringe is
washed with solvent A before the sample washes.
Advanced User Guide
351
12 7683B Sampler
Solvent B post washes (0-15) How many times the syringe is
washed with solvent B after any solvent A washes.
Solvent B pre washes (0-15) How many times the syringe is
washed with solvent B after any solvent A prewashes and before
the sample washes.
Solvent B wash volume The percent of the syringe volume to be
used for solvent B washes.
Sample Draw Speed Speed of the syringe plunger when
drawing in sample.
Sample Disp Speed Speed of the syringe plunger when
dispensing sample.
Solvent Draw Speed Speed of the syringe plunger when
drawing in solvent.
Solvent Disp Speed Speed of the syringe plunger when
dispensing solvent.
Pre dwell time (0-1) How long, in minutes, the needle remains
in the inlet before the injection.
Post dwell time (0-1) How long, in minutes, the needle remains
in the inlet after injection.
Sample offset (-2 to 30, Off) Sets variable sampling depth.
Injection Reps (1-99) How many times the injection and
analysis should be repeated from each vial.
Injection Delay Time between multiple injections. Availability
depends on the inlet type.
Solvent Saver
If you enter a non- zero value for any of the solvent or sample
washes, the GC will ask for the wash volume. The default is 80%
of the syringe volume. Press [Mode/Type] to see the other
choices. This function allows you to conserve solvent during the
washes.
352
Advanced User Guide
12
7683B Sampler
Sample tray setpoints
The sample tray delivers sample vials to the front and rear
injectors according to the defined sequence parameters. There
is a separate set of sequence parameters for each injector. The
sample tray delivers vials to the front injector before the rear
injector. Stored sequences and bar code configurations can be
used to tell the sample tray where to deliver and retrieve sample
vials.
Enable bar code
Turns the bar code reader on or off.
1 Press [Sample tray] to access the sample tray and bar code
reader setpoints.
2
Press [On] or [Off] to enable or disable the tray.
3
Press [On] or [Off] to enable or disable the bar code reader.
Storing setpoints
After setting up injector setpoints, sample tray setpoints and
bar code reader configurations, store them as part of a method
by following the procedures in To store a method from the
keypad. This method becomes a part of the sequence used to
run the samples.
Advanced User Guide
353
12 7683B Sampler
354
Advanced User Guide
Agilent 7890A Gas Chromatograph
Advanced User Guide
13
Cables
About Cables and Back Panel Connectors 356
Back panel connectors 356
Sampler connectors 356
The AUX connector 356
Signal connectors 357
REMOTE connector 357
EVENT connector 357
BCD input connector 357
RS-232 connector 357
LAN connector 357
Using the Remote Start/Stop cable 358
Cable Diagrams 363
Analog cable, general use 363
Remote start/stop cable 363
BCD cable 364
External event cable 365
Agilent Technologies
355
13 Cables
About Cables and Back Panel Connectors
Some parts of an analysis system are connected to the GC by
cables. These cables and the back panel connectors to which
they connect are described in this section.
Back panel connectors
These are the connectors on the back panel of the GC:
SIG 1
SIG 2
SAMPLER 1
SAMPLER 2
TRAY
REMOTE
AUX
EVENT
BCD
LAN
RS-232
Sampler connectors
If using an ALS, connect to the GC using the following
connectors:
SAMPLER 1 An injector, usually the front injector. (For 7693A,
the configuration does not matter. For a the 7683, typically
configured as INJ1.)
SAMPLER 2 A second injector, usually the back injector. (For
7693A, the configuration does not matter. For a the 7683,
typically configured as INJ2.)
TRAY
The sample tray and (optional) barcode reader.
The AUX connector
This connector is reserved for future development.
356
Advanced User Guide
Cables
13
Signal connectors
SIG1 and SIG2 are for the two analog output signals.
REMOTE connector
Provides a port to remotely start and stop other instruments. A
maximum of 10 instruments can be synchronized using this
connector. See “Using the Remote Start/Stop cable” on page 358
for more detail.
EVENT connector
This connector provides two passive contact closures and two
24- volt outputs for controlling external devices. The outputs are
controlled by valve drivers 5 through 8.
BCD input connector
This connector provides two control relays and a BCD input for
a stream selection valve.
CAUTION
This connector is similar to the EVENT connector. Plugging a
non BCD cable into the BCD connector can damage the GC.
RS-232 connector
This connector is reserved for future development.
LAN connector
Standard Local Area Network connector, for communication
with data systems and other devices.
Advanced User Guide
357
13 Cables
Using the Remote Start/Stop cable
Remote start/stop is used to synchronize two or more
instruments. For example, you might connect an integrator and
the GC so that the [Start]/[Stop] buttons on either instrument
control both of them. You can synchronize a maximum of ten
instruments using Remote cables.
Connecting Agilent products
If connecting two Agilent products with Remote cables, the
sending and receiving circuits will be compatible—just plug in
both ends of the cable.
Connecting non-Agilent products
If connecting to a non- Agilent product, the following
paragraphs contain information you will need to ensure
compatibility.
APG Remote signal electrical specifications
The APG signals are a modified open collector type. The signal
levels are generally TTL levels (low voltage is logic zero, high
voltage is logic one) but the open circuit voltage will be between
2.5 and 3.7 Volts. The typical voltage is 3 Volts. A voltage over
2.2 volts will be interpreted as a high logic state while a voltage
below 0.4 volts will be interpreted as a low logic state. These
levels provide some margin over the specifications of the
devices used.
The pull- up resistance, connected to the open- circuit voltage, is
in the range of about 1K ohms to 1.5K ohms. For a logic- low
state, for a single device on the bus, the minimum current you
must be able to sink is 3.3 milliamps. Since devices are
connected in parallel, when you have multiple devices this
minimum current must be multiplied by the number of devices
attached on the bus. The maximum voltage for a low- input
state = 0.4V.
The bus is passively pulled high. Leakage current out of a port
must be less than 0.2 milliamps to keep the voltage from being
pulled lower than 2.2 volts. Higher leakage current may cause
the state to be interpreted as a low.
Over- voltage protection - APG Remote connections are clamped
by a zener diode to 5.6 Volts. Exceeding this voltage will damage
the circuit (main board).
358
Advanced User Guide
Cables
13
APG Remote - Suggested drive circuits
A signal on the APG bus may be driven by another APG device
or by one of the following circuits:
• A relay, with one side connected to ground, when closed will
set a logic- low state.
• An NPN transistor, with the emitter connected to ground and
the collector connected to the signal line will set a logic- low
state if proper base current is supplied.
• An open- collector logic gate will perform this same function.
• A low- side drive IC will also work, but Darlington- type
drivers should be avoided as they will not meet the low- side
voltage requirement of less than 0.4V
APG Remote connector
Pin
1
5
6
9
Function
Logic
1
Digital ground
2
Prepare
LOW true
3
Start
LOW true (input)
4
Start relay
5
Start relay
6
not used
7
Ready
HIGH true (output)
8
Stop
LOW true
9
not used
APG Remote signal descriptions
Prepare (Low True) Request to prepare for analysis. Receiver is
any module performing pre- analysis activities. For example,
shorting pin 2 to ground will put the GC into Prep Run state. This
is useful for Splitless Mode to prepare the inlet for injection or
when using the Gas Saver. This function is not needed by Agilent
autosampler systems.
Ready (High True) If The Ready Line is high (> 2.2 VDC) then
the system is ready for next analysis. Receiver is any sequence
controller.
Advanced User Guide
359
13 Cables
Start (Low True) Request to start run/timetable. Receiver is
any module performing runtime- controlled activities. The 7890
GC requires a pulse duration of at least 500 micro- seconds to
sense a start from an external device.
Start Relay (Contact Closure) A 120 millisecond contact closure
– used as an isolated output to start another device that is not
compatible or connected with APG Remote pin 3.
Stop (Low True) Request to reach system ready state as soon as
possible (for example, stop run, abort or finish, and stop
injection). Receiver is any module performing
runtime- controlled activities. Normally this line is not
connected, if the GC oven program is used to control the
method Stop time.
Prepare
System Ready
Waiting for Ready
Postrun
Runtime elapsed/Start
Run
Injection/Start
Injection cycle started
Start Requested
System Ready
Not Ready during Prep
Request for Prepare
System Ready
Waiting for Ready
APG Remote timing diagram
H
L
Start
H
L
Stop
H
L
H
Ready
360
H
H
L
Advanced User Guide
Cables
13
Connecting Cables
Connect a GC to an Agilent data system computer using LAN
communications using a LAN cable. See Figure 4 below.
LAN hub/switch
Crossover LAN cable 5183-4648
LAN cable
8121-0940
GC
LAN cable
8121-0940
Computer
Computer
GC
Figure 4 Connecting the GC and computer with a hub/switch (shown at left) or a crossover cable (shown at
right).
Table 77
Typical IP addresses for an isolated LAN
GC
Computer
IP address
10.1.1.101
10.1.1.100
Subnet mask
255.255.255.0
255.255.255.0
A single communications LAN cable is supplied with the GC.
The hub and other cables must be ordered separately, if needed.
See Table 77 and Table 78 for cabling requirements for other
configurations.
Table 78
Advanced User Guide
Cabling requirements
7890A GC connected to:
Required Cable(s)
Part number
7693A Automatic Liquid
Sampler
Injector cable or tray
cable
G4514-60610
7683 Automatic Liquid
Sampler
Injector cable is integral
Tray cable
G1289B/G1290B
Headspace Sampler
Remote, 9-pin
male/6-pin connector
G1530-60930
7695 Purge and Trap
Sampler
Remote, 25-pin
male/9-pin male
G1500-60820
G2614-60610
361
13 Cables
Table 78
Table 79
Cabling requirements (continued)
7890A GC connected to:
Required Cable(s)
Part number
CTC automatic sampler
Remote,
3395B/3396C Integrator
Remote, 9 pin/15 pin
Analog, 2 m, 6 pin
03396-61010
G1530-60570
Non-Agilent
Integrator
General purpose analog
signal cable
2 m, 6 pin
G1530-60560
Mass Selective Detector
Remote, 2-m, 9-pin
male/9-pin male
G1530-60930
Non-Agilent
data system
General use remote,
9-pin male/spade lugs
(various lengths)
35900-60670 (2 m),
35900-60920 (5 m),
35900-60930 (0.5 m)
Non-Agilent
instrument, unspecified
External event, 8
pin/spade lugs
G1530-60590
Stream selection valves
Gas sampling valves
See documentation
accompanying the valve
LAN
Cable, networking CAT 5, 8121-0940
25 feet
Cable, LAN, crossover
5183-4648
Cabling for other instruments in a 7890A system
Instrument 1
Instrument 2
Type of cable
Part no.
Modem
PC
Modem, 9-pin
female/9-pin male, or
Modem, 9-pin
female/25-pin male
G1530-61120,
or
24540-80012
Mass Selective Detector
Purge & Trap or
Headspace sampler
Splitter ("Y") cable for
remote, 1 male and 2
female connectors
G1530-61200
Splitter ("H") cable for
35900-60800
APG remote, 2 male and 2
female connectors
362
Advanced User Guide
Cables
13
Cable Diagrams
Analog cable, general use
Connector 1
Connector 2
The pin assignments for the general use analog out cable are
listed in Table 80.
Table 80
Analog cable, general use, output connections
Connector 1
Connector 2, wire color
Signal
1
Brown or violet
Not used
2
White
0 to 1 V, 0 to 10 V (–)
3
Red
Not used
4
Black
1 V (+)
6
Blue
10 V (+)
Shell
Orange
Ground
Remote start/stop cable
Connector 1
Connector 2
The pin assignments for the remote start/stop cable are listed in
Table 81.
Advanced User Guide
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13 Cables
Table 81
Remote start/stop cable connections
Connector 1, 9-pin male
Connector 2, wire color
Signal
1
Black
Digital ground
2
White
Prepare (low tone)
3
Red
Start (low tone)
4
Green
Start relay (closed during
start)
5
Brown
Start relay (closed during
start)
6
Blue
Open circuit
7
Orange
Ready (high true input)
8
Yellow
Stop (low tone)
9
Violet
Open circuit
BCD cable
The BCD connector has eight passive inputs that sense total
binary- coded decimal levels. The pin assignments for this
connector are listed in Table 82.
Table 82
364
BCD input connections
Pin
Function
Maximum rating
1
Relay
48 V AC/DC, 250 mA
2
Relay
48 V AC/DC, 250 mA
3
LS digit 0
4
LS digit 1
5
LS digit 2
6
LS digit 3
7
MS digit 0
8
Ground
Shield
Chassis ground
Advanced User Guide
Cables
13
External event cable
6
3
7
4
1
8
5
2
Connector 1
Connector 2
Two passive relay contact closures and two 24- volt control
outputs are provided. Devices connected to the passive contact
closures must be connected to their own power sources.
The pin assignments for this cable are listed in Table 83.
Table 83
External events cable
Connector 1 pin
Signal name
Maximum rating
Connector 2, wire
color
Controlled by valve #
1
24 V output 1
75 mA
Yellow
5
2
24 V output 1
75 mA
Black
6
3
Ground
Red
4
Ground
White
24 volts output
Relay contact closures (normally open)
5
Closure 1
6
Closure 1
7
Closure 2
8
Closure 2
Advanced User Guide
48 V AC/DC, 250 mA
48 V AC/DC, 250 mA
Orange
7
Green
7
Brown or violet
8
Blue
8
365
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366
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Agilent 7890A Gas Chromatograph
Advanced User Guide
14
GC Output Signals
About Signals 368
Signal Types 369
Value 369
Analog Signals 371
Analog zero 371
Analog range 371
Analog data rates 372
Selecting fast peaks (analog output) 373
Digital Signals 374
Digital zero 374
Baseline level shifts 374
Agilent data systems 375
Column Compensation 378
Creating a column compensation profile 379
Making a run using analog output column compensation 379
Plotting a stored column compensation profile 380
Test Plot 381
Agilent Technologies
367
14 GC Output Signals
About Signals
Signal is the GC output to a data handling device, analog or
digital. It can be a detector output or the output from flow,
temperature, or pressure sensors. Two signal output channels
are provided.
Signal output can be either analog or digital, depending on your
data handling device. Analog output is available at either of two
speeds, suitable to peaks with minimum widths of
0.004 minutes (fast data rate) or 0.01 minutes (normal rate).
Analog output ranges are 0 to 1 V, 0 to 10 V, and 0 to 1 mV.
Digital output rates are set by your Agilent data system, such as
ChemStation or EZChrom.
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GC Output Signals
14
Signal Types
When assigning detector signals, use the [Mode/Type] key and
choose from the Signal Type parameter list, or press a key or
combination of keys.
[Front], [Back], [–], and [Column Comp] will work, alone or in
combination. For example, press [Back] for back detector or
[Back][–][Front] for back detector minus front detector. The
menu choices for signal subtraction (Front - Back and Back Front) only appear if the front and back detectors are of the
same type.
The nondetector signals are test plot, thermal, pneumatic, and
diagnostic. Access them by pressing [Mode/Type]. Diagnostic
signals are for use by your service representative and are not
described in detail here.
Signal type can be programmed as a run time event.
Value
Value on the signal parameter list is the same as Output on the
detector parameter list if your signal type is Front or Back. If you
are subtracting one signal from another (as in Front – Back), the
signal Value will be the difference. You cannot enter a setpoint
for Value.
A conversion factor may be involved when interpreting
Value—for example, one FID unit is one picoamp; one uECD unit
is 1 Hz. The units for detector and other signals are listed below.
Table 84
Signal type
Signal conversions
1 display unit is equivalent to:
Detector:
FID, NPD
1.0 pA (1.0 × 10-12 A)
FPD
150 pA (150 ×10-12 A)
TCD
25 mV (2.5 × 10-5 V)
µECD
1 Hz
Analog input board (use to connect the 15 µV
GC to non-Agilent detector)
Nondetector:
Thermal
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1 °C
369
14 GC Output Signals
Table 84
370
Signal conversions (continued)
Signal type
1 display unit is equivalent to:
Pneumatic:
Flow
Pressure
Diagnostic
1 mL/min
1 pressure unit (psi, bar, or kPa)
Mixed, some unscaled
Advanced User Guide
14
GC Output Signals
Analog Signals
If you use an analog recorder, you may need to adjust the signal
to make it more usable. Zero and Range in the Signal parameter
list do this.
Analog zero
Zero Subtracts value entered from baseline. Press [On/Yes] to
set to current Value or [Off/No] to cancel.
This is used to correct baseline elevation or offsets. A common
application is to correct a baseline shift that occurs as the result
of a valve operation. After zeroing, the analog output signal is
equal to the Value line of the parameter list minus the Zero
setpoint.
Zero can be programmed as a run time event. For details, see
“Run Time Programming” on page 14.
1 Verify that the detector is on and in a ready state.
2
Press [Analog Out 1] or [Analog Out 2].
3
Scroll to Zero.
4
Press [On/Yes] to set Zero at the current signal value,
or
Enter a number between - 500000 and +500000. A value
smaller than the current Zero shifts baseline up.
Analog range
Range Scales data coming from the detector
Range is also referred to as gain, scaling, or sizing. It sizes the
data coming from the detector to the analog signal circuits to
avoid overloading the circuits (clamping). Range scales all
analog signals.
If a chromatogram looks like A or B in the next figure, the data
needs to be scaled (as in C) so that all peaks are visible on the
paper.
Valid setpoints are from 0 to 13 and represent 20 (=1) to 213
(=8192). Changing a setpoint by 1 changes the height of the
chromatogram by a factor of 2. The following chromatograms
illustrate this. Use the smallest possible value to minimize
integration error.
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14 GC Output Signals
A: Range = 0
B: Range = 3
C: Range = 1
There are limits to usable range settings for some detectors. The
table lists the valid range setpoints by detector.
Table 85
Range limits
Detector
Usable range settings (2x)
FID
0 to 13
NPD
0 to 13
FPD
0 to 13
TCD
0 to 6
υECD
0 to 6
Analog input
0 to 7
Range may be run time programmed. See “Run Time
Programming” on page 14 for details.
Analog data rates
Your integrator or recorder must be fast enough to process data
coming from the GC. If it cannot keep up with the GC, the data
may be damaged. This usually shows up as broadened peaks
and loss of resolution.
Speed is measured in terms of bandwidth. Your recorder or
integrator should have a bandwidth twice that of the signal you
are measuring.
The GC allows you to operate at two speeds. The faster speed
allows minimum peak widths of 0.004 minutes (8 Hz
bandwidth), while the standard speed allows minimum peak
widths of 0.01 minutes (1.6 Hz bandwidth).
If you use the fast peaks feature, your integrator should operate
at around 15 Hz.
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Selecting fast peaks (analog output)
1 Press [Config][Analog 1] or [Config][Analog 2].
2
Scroll to Fast peaks and press [On].
Agilent does not recommend using Fast peaks with a thermal
conductivity detector. Since the gas streams switch at 5 Hz, the
gain in peak width is offset by increased noise.
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14 GC Output Signals
Digital Signals
The GC outputs digital signals only to an Agilent data system.
The following discussions describe features that impact the data
sent to data systems, not the analog data available to
integrators.
Digital zero
Digital signal outputs respond to the Zero command by
subtracting the signal level at the time of the command from all
future values.
Baseline level shifts
Some run time operations, such as changing signal assignment
or switching a valve, can produce large changes in the signal
baseline position. This can complicate signal processing by
external devices. The GC provides two run table commands to
minimize such problems with digital output—see “Run Time
Programming” on page 14.
Store signal value
the command.
Saves the value of the signal at the time of
Signal zero – value Creates a new zero by subtracting the
stored value from the current value of the signal and applies
this zero to all future values.
When these commands surround a baseline- shifting command,
the effect is to bring the new baseline to the previous level, as
shown in the next figure.
The Store signal value event must occur before the event that
shifts the baseline, and the Signal zero – value event must occur
after the baseline has stabilized at the shifted level.
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No correction
Baseline level change
Baseline shifting event occurs
3. Sig zero - val event occurs
Run time correction
2. Baseline shifting event occurs
1. Store signal value event occurs
Agilent data systems
The GC can process data at various data rates, each
corresponding to a minimum peak width. The table shows the
effect of data rate selection.
Table 86
Advanced User Guide
EZChrom Elite/ChemStation data processing
Data rate, Hz
Minimum peak
width, minutes
Relative
noise
Detector
Column type
500
0.0001
5
FID
Narrow-bore,
0.05 mm
200
0.001
3.1
FID
Narrow-bore,
0.05 mm
100
0.002
2.2
FID/FPD/NPD
only
Capillary
50
0.004
1.6
20
0.01
1
10
0.02
0.7
5
0.04
0.5
2
0.1
0.3
to
All types
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14 GC Output Signals
Table 86
EZChrom Elite/ChemStation data processing (continued)
Data rate, Hz
Minimum peak
width, minutes
Relative
noise
1
0.2
0.22
0.5
0.4
0.16
0.2
1.0
0.10
0.1
2.0
0.07
Detector
Column type
Slow packed
You cannot change the data rate during a run.
You will see higher relative noise at the faster sampling rates.
Doubling the data rate can double peak height while the relative
noise increases by 40%. Although noise increases, the
signal- to- noise ratio is better at the faster rates.
This benefit only occurs if the original rate was too low, leading
to peak broadening and reduced resolution. We suggest that
rates be chosen so that the product of data rate and peak width
in seconds is about 10 to 20.
The figure shows the relationship between relative noise and
data rates. Noise decreases as the data rate decreases until you
get to data rates of around 5 Hz. As the sampling rate slows,
other factors such as thermal noise increase noise levels.
Relative noise level
Excess noise (due to flow,
oven temperature, detector
block temperatures, etc.)
Faster data rates
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Slower data rates
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GC Output Signals
14
Zero Init Data Files
This feature applies to digital output only, and is mainly
intended for non- Agilent data systems. It may help systems that
have trouble with non- zero baseline output.
When you turn it On, the GC immediately begins to subtract the
current detector output value(s) from any future values. For
example, if you turn it on when the output is 20 pA, the GC
subtracts 20 pA from the digital output until you turn Zero Init
Data Files Off.
You will not see any change in the GC display, but you will see
the change in the online plot available in the data system.
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14 GC Output Signals
Column Compensation
In temperature programmed analysis, bleed from the column
increases as the oven temperature rises. This causes a rising
baseline which makes peak detection and integration more
difficult. Column compensation corrects for this baseline rise.
A column compensation run is made with no sample injected.
The GC collects an array of data points from all 4 detectors,
whether installed, off, or working. If a detector is not installed
or is turned off, that part of the array is filled with zeros.
One array (Column compensation 1) can be created for analog
signals. Two independent arrays (Column compensation 1 and
2) can be created for digital signals.
Each array defines a set of curves, one for each detector, that
can be subtracted from the real run to produce a flat baseline.
The next figure illustrates the concept.
Chromatogram with
rising baseline
Blank column
compensation
profile
Chromatogram with
column compensation
All conditions must be identical in the column compensation
run and the real run. The same detector and column must be
used, operating under the same temperature and gas flow
conditions.
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Creating a column compensation profile
1 Set up the instrument for a run.
2
Make a blank run to verify that the baseline is clean. This is
particularly important for new conditions or if the GC has
been idle for several hours.
3
Press [Column Comp].
4
Select Col comp 1 or Col comp 2 (these are the two arrays).
5
Select Start compensation run and press [Enter].
6
If the run is successful, the first line of the parameter list
will say Data ok, and a time and date will appear at the
bottom.
Making a run using analog output column compensation
1 Set the chromatographic conditions. They must be identical
to those in the stored column compensation run except that
Final time in the last ramp of the oven program can be longer
or shorter.
2
Press [Analog Out 1] or [Analog Out 2].
3
Scroll to Type and press [Mode/Type].
4
The choices for an analog signal are:
Front detector
Back detector
Front - column comp 1
Front column compensation 1
Back column compensation 1
Aux 1 column compensation 1
Aux 2 column compensation 1
Test plot
5
Choose an option from the list.
6
Enter setpoints for Zero and Range, if applicable.
7
Start your run.
Making a run using digital output column compensation
1 Set each detector output separately.
2
Press [Config][Detector name]. Scroll to Signal and press
[Mode/Type]. Select from:
No Column Compensation
Detector - ColComp 1
Detector - ColComp 2
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14 GC Output Signals
This changes the digital output. You cannot get both
compensated and uncompensated digital data from the same
detector at the same time. However, it does not affect the analog
output.
Plotting a stored column compensation profile
1 Press [Analog Out 1] or [Analog Out 2].
380
2
Scroll to Type: and press [Mode/Type].
3
Select the profile to be plotted.
4
Press [Start].
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GC Output Signals
14
Test Plot
Test plot is an internally generated “chromatogram” that can be
assigned to a signal output channel. It consists of three
baseline- resolved, repeating peaks. The area of the largest is
approximately 1 Volt- sec, the middle one is 0.1 times the
largest, and the smallest is 0.01 times the largest.
Test plot can be used to verify the operation of external data
processing devices without having to perform repeated
chromatographic runs. It may also be used as a stable signal to
compare the results from different data processing devices.
To use the Test Plot:
1 Press [Analog Out 1] or [Analog Out 2].
2
Scroll to Type: and press [Mode/Type].
3
Choose Test Plot.
4
Press [Start]. The plot will repeat until you press [Stop].
Test Plot is the default choice for the analog outputs.
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Agilent 7890A Gas Chromatograph
Advanced User Guide
15
Miscellaneous Topics
Auxiliary Devices 384
About Auxiliary Pressure Control 384
About Aux Thermal Zone Control 385
About Auxiliary Device Contacts 385
About the 24V Auxiliary Device Power Supply 385
About Auxiliary Columns 385
About Auxiliary Detectors 386
To Use the Stopwatch 387
Service Mode 388
Service Reminders 388
Agilent Technologies
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15 Miscellaneous Topics
Auxiliary Devices
About Auxiliary Pressure Control
Pressure units
There are two common ways of expressing gas pressures:
psia
Absolute pressure, measured relative to vacuum.
psig Gauge pressure, measured relative to atmospheric
pressure. This name is used because most pressure gauges have
one side of the sensing element exposed to the atmosphere.
The two measurements are related by:
psia = psig + atmospheric pressure
Two-channel pressure control module (PCM)
The PCM has two different channels. Channel 1 may be either
flow or pressure controlled and may be flow/pressure
programmed. It is essentially identical to the packed column
inlet flow module (see “About the Multimode Inlet” on
page 186).
Channel 2 is pressure only, but may be used in either a forwardor back- pressure mode by changing connections.
Both channels are controlled by the same parameter list. The
first two lines are for channel 1; the remaining lines are for
channel 2.
The forward- pressure mode requires the user to supply a
downstream flow resistance, possibly a frit.
The back- pressure mode is most useful with gas sampling
valves. By connecting the sample exit line from the valve to the
vent fitting of the PCM, pressure in the sample loop can be
controlled.
Three-channel auxiliary pressure controller (Aux PCM)
All channels are 3- ramp programmable. Up to three modules
may be installed, for a total of 9 pressure- regulated channels.
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Miscellaneous Topics
Setting parameters for auxiliary pressure control
1 Press [Aux EPC #] and scroll to the channel you wish to
control. Press [Enter].
2
Scroll to Initial pressure. Enter a value and press [Enter].
3
If desired, enter a pressure program using the time and rate
functions.
4
Press [On/Yes] to apply Initial pressure and start the program.
About Aux Thermal Zone Control
There can be up to 3 aux thermal controlled zones.
These zones are 3- ramp programmable.
Run time events may be used to schedule specific temperatures
during the run.
Setting parameters for the aux thermal zone control
1 Press [Aux Temp #] and scroll to the zone you wish to control.
Press [Enter].
2
Scroll to Temperature. Enter a value and press [Enter].
3
Scroll to Initial time. Enter a value and press [Enter].
4
Scroll to Rate 1. Enter 0 to end the program here or a positive
value to create a temperature program.
About Auxiliary Device Contacts
These contacts are controlled by the external valve drivers. See
“The external valve drivers” on page 342.
About the 24V Auxiliary Device Power Supply
This is controlled by the external valve drivers. See “The
external valve drivers” on page 342.
About Auxiliary Columns
Defines up to 6 columns (includes Col 1 and Col 2).
1 Press [Config][Aux Col #] and enter a column number. Press
[Enter].
2
Advanced User Guide
Define/configure the column. See “Column #” on page 33 for
details.
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15 Miscellaneous Topics
About Auxiliary Detectors
The GC supports up to two auxiliary detectors in addition to the
Front and Back detectors that mount on the top of the oven.
Aux Det # 1 This can only be a TCD, and mounts in a carrier
on the left side of the oven together with its flow module.
Aux Det # 2 This can only be an analog input board (AIB). It is
used to receive and process data from a non- Agilent detector or
other source.
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To Use the Stopwatch
In the stopwatch mode, both the time (to 0.1 second) and
reciprocal time (to 0.01 min- 1) are displayed. The stopwatch is
useful when measuring flows with a bubble flowmeter.
1 Press [Time] and scroll to the time = line.
2
Press [Enter] to start the stopwatch.
3
Press [Enter] again to stop.
4
Press [Clear] to set to zero.
You can access other functions while the stopwatch is running.
Press [Time] again to view the stopwatch display.
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15 Miscellaneous Topics
Service Mode
The [Service Mode] key presents the Service Reminders and other
functions.
Service Reminders
Internal counters
This is a set of 12 counters that monitor the use of various items
on the GC, such as syringes, septa, and columns. These counters
only count runs and their definitions are fixed. You can set
limits for each item; when a limit is reached, the Service Due light
on the status board comes on. Examine the limits to identify the
item that has reached its limit.
You may enter a limit for each item, reset a count to 0 by
pressing [Off/No], or disable a counter by entering a limit of 0.
Advanced counters
The GC provides storage for 64 advanced counters. They each
have two thresholds, and the actions based on these counters
can be: do nothing, turn on the Service Due light, or light the
Service Due light and go Not ready.
Advanced counters are not accessible through the GC keyboard,
except for the Disable Advanced Counters function of the Service
Reminders. If they are not disabled, they continue to count, and
continue to act on the set thresholds. This could cause the GC to
become Not ready.
Since the advanced counters cannot be reset or manipulated
without the Agilent G4600AA Lab Advisor software. Disable
Advanced Counters is provided so that they can be turned off from
the GC keyboard by someone who does not wish to use them,
the Lab Advisor software, or an Agilent data system. These
users should disable the advanced counters from the keypad to
avoid possible problems.
Counters can be individually enabled (count or don’t count),
individually reset (start over), and individually set as counting
elapsed seconds or runs. They can be assigned arbitrary
“meanings”, allowing you to set up counters for equipment of
your choice.
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15
Each counter has an ID that can be associated with a concept,
such as front inlet gold seal, and can count the number of
elapsed runs or seconds since the last reset, from which one can
infer the gold- seal’s in- service time or count.
A ChemStation can enable or disable individual counters in
association with a method, so that only the counters for things
used by the method advance.
Other functions
These are for use by trained Agilent personnel. They are
described in the Service Manual.
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Advanced User Guide
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