Chapter 1 TRACE GC Ultra Configuration

Chapter 1 TRACE GC Ultra Configuration
TRACE GC
Gas Chromatograph Setup
User’s Manual
Published by Technical Publications, Thermo Finnigan Italia S.p.A
Strada Rivoltana
20090 Rodano-Milan
Italy
Printing History: Revision E printed March 2003.
Xcalibur™ and TRACE ™ GC Ultra are trademarks and/or product names of Finnigan Corporation. Microsoft® is a registered trademark
of Microsoft Corporation.
Technical information contained in this publication is for reference purposes only and is subject to change without notice. Every effort
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will not be liable for any errors, omissions, damage, or loss that might result from any use of this manual or the information contained
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supersede all previous information and are subject to change without notice.
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Contents
Chapter 1
TRACE GC Ultra Configuration ...............................................................................................7
Introduction ...........................................................................................................................................8
To open this view: 8
General Page .......................................................................................................................................10
Inlets Page ...........................................................................................................................................11
Detectors and Data Page .....................................................................................................................13
Auxiliary Page ....................................................................................................................................15
Road Map Home Page Status Tabs .....................................................................................................18
Status Tabs ...........................................................................................................18
Status ....................................................................................................................18
Temperatures page ...............................................................................................19
Flows page ...........................................................................................................19
Pressure page .......................................................................................................19
Keypad .................................................................................................................19
Chapter 2
TRACE Menu .............................................................................................................................21
Menu Description ................................................................................................................................22
Using Flow Calculator ........................................................................................................................25
Column Flow Calculator Page .............................................................................25
Using slider bar and buttons ................................................................................26
Related Topics .....................................................................................................27
Using Vapor Calculator .......................................................................................................................31
Vapor Calculator Page .........................................................................................31
Related Topics .....................................................................................................33
Chapter 3
Instrument Setup ........................................................................................................................35
Edit TRACE GC Ultra Parameters ......................................................................................................36
Introduction ..........................................................................................................36
To open this view: ................................................................................................36
Using the TRACE Tabs .......................................................................................36
Related Topics .....................................................................................................37
Oven Page ...........................................................................................................................................38
Oven Page Parameters .........................................................................................38
Setting Up Oven Ramp Parameters .....................................................................40
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UFM Page .......................................................................................................................................... 42
UFM Page Parameters ......................................................................................... 42
Setting Up UFM Ramp Parameters .................................................................... 44
SSL Page ............................................................................................................................................ 45
SSL Page Parameters .......................................................................................... 45
Setting Up SSL Parameters ................................................................................. 47
OCI Page ............................................................................................................................................ 49
OCI Page Parameters .......................................................................................... 49
Setting Up Parameters for an OCI ...................................................................... 50
HOTOC Page ..................................................................................................................................... 51
Setting Up Parameters for an HOTOC ................................................................ 52
LVOCI Page 53
Setting Up Parameters for an LVOCI ................................................................. 54
Operating Precautions for the LVOCI ................................................................ 56
Tips for Performing Large Volume Injections .................................................... 56
PKD Page ........................................................................................................................................... 58
Setting Up Parameters for PKD .......................................................................... 59
PPKD Page ......................................................................................................................................... 60
Setting Up Parameters for PPKD ........................................................................ 62
PTV Page ............................................................................................................................................ 63
Setting Up Parameters for PTV ........................................................................... 67
Carrier Page ........................................................................................................................................ 68
Flow Mode list box ............................................................................................. 69
Setting Up Parameters for Constant Flow Mode ................................................ 73
Setting Up Parameters for Constant Pressure Mode ........................................... 74
Setting Up Parameters for Programmed Flow Mode .......................................... 74
Setting Up Parameters for Programmed Pressure Mode ..................................... 75
ECD Page .......................................................................................................................................... 77
ECD Parameters .................................................................................................. 77
Setting Up Parameters for ECD .......................................................................... 78
FID Page ............................................................................................................................................. 79
FID Parameters .................................................................................................... 79
Setting Up Parameters for FID ............................................................................ 81
NPD Page ........................................................................................................................................... 82
NPD Parameters .................................................................................................. 83
Setting Up Parameters for NPD .......................................................................... 84
TCD Page ........................................................................................................................................... 85
TCD Parameters .................................................................................................. 85
Setting Up Parameters for TCD .......................................................................... 87
FPD Page ............................................................................................................................................ 88
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FPD Parameters ...................................................................................................88
Setting Up Parameters for FPD ...........................................................................89
PID Page ..............................................................................................................................................90
PID Parameters ....................................................................................................90
Setting Up Parameters for PID ............................................................................91
Aux Zones Page ..................................................................................................................................92
Aux Zones Parameters .........................................................................................92
Setting Up Parameters for Aux Zones .................................................................93
Run Table Page ..................................................................................................................................94
Run Table Parameters ..........................................................................................94
Setting Up Parameters for Run Table ..................................................................95
Using the Add/Event Run-Time Event Dialog ....................................................96
Chapter 4
How To.... .....................................................................................................................................99
Installing the Desolvation Column and Connecting the Tee .............................................................100
Characterizing Columns ....................................................................................................................101
Post Column Splitting of the GCQ with the Flame Ionization Detector ...........................................102
Introduction: .......................................................................................................102
Installing the System to Meet Instrument Specifications: .................................102
Connecting a Post Column SGE Splitter: ..........................................................102
Calculating Transfer Line Dimensions for the Mass Spec and the GC Detector 103
Installing the Post Column Splitter: ...................................................................104
Setting up the Carrier Flow: ...............................................................................105
Leak Checking: ..................................................................................................105
Evaluating the DFPC Modules for the Detector and Carrier Gases: .................105
Operating an FID with Xcalibur Software ........................................................................................107
Introduction: .......................................................................................................107
Configuring Xcalibur and the TRACE GC Ultra: .............................................107
Connecting the Gases: .......................................................................................107
Installing the Test Column: ................................................................................108
Column Characterization: ..................................................................................108
Igniting the Flame: .............................................................................................108
Setting up the Method: .......................................................................................108
Setting up a Sequence in Xcalibur for Acquisition of the FID Only: ................109
Setting Up Qual Browser for the FID Analog Chromatogram: .........................111
Meeting FID Specifications: ..............................................................................112
Simultaneous Analysis on the Ion Trap and the FID 113
Configuration: ....................................................................................................113
Instrument Method Set Up: ................................................................................113
Opening a Data File in Qual Browser: ...............................................................114
Developing a Processing Method: .....................................................................117
Report Writing: ..................................................................................................120
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Chapter 5
Glossary .....................................................................................................................................121
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Chapter 1
TRACE GC Ultra Configuration
This chapter contains the instruction to configure your TRACE GC Ultra.
This chapter contains these topics:
Introduction
8
General Page
10
Inlets Page
11
Detectors and Data Page
13
Auxiliary Page
15
Road Map Home Page Status Tabs
18
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TRACE GC Ultra Configuration
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1.1 Introduction
This dialog box is available from the Instrument Configuration window.
Figure 1-1. TRACE GC Ultra Configuration Window
Select the TRACE GC Ultra and then select the configure button. The
following TRACE GC Ultra detector pages display:
GET
•
General Page
•
Inlets Page
•
Detectors and Data Page
•
Auxiliary Page
Use this button any time you want to automatically enter the configurations
already entered into your TRACE GC Ultra. This program automatically
enters the exact configuration parameters that were programmed into the
TRACE GC Ultra key panel (embedded system). However, you will still
have to enter the channel parameters located on the Detectors and Data page.
To open this view:
1. Choose Start | Programs | Xcalibur | Instrument Configuration
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2. Click the TRACE GC Ultra button located in the Available Devices
column.
3. Click Add, then Configure.
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TRACE GC Ultra Configuration
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1.2 General Page
Figure 1-2. General Page
Connection Group Box
Serial Port
Network Address
ADVANCED
Select the COM port in which your TRACE is connected. A COM port is a 9pin cable connection located on the back of your computer.
Enter the I.P. address to allow the LAN control of the GC through the
Thermo data systems.
Select this button to set the LAN communication port used by the TCP-IP
ptotocol and timeout.
Options Group Box
Pressure Units
1-10
Specify the pressure unit measurement to use in your work sessions. Pressure
measurement units to select include kPa, bar, and psi.
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1.3 Inlets Page
Use this page to select the inlets installed on the top of your TRACE GC
Ultra. The inlet you select determines which options are available on this
page and the instrument setup (method editor) pages.
Figure 1-3. Inlet Page.
Inlets Group Box
Choose the inlet installed on the left or right side of your TRACE GC Ultra.
Left Inlets
Right Inlets
Choose one: None, SSL, OCI, HOTOC, LVOCI, PKD, PPKD
Choose one: None, SSL, PTV, PKD, PPKD
Left and Right Valves Group Box
Select the following to further control your selected inlet.
SVE Valve
Check this box to display Sub Ambient controls in the selected inlet’s
instrument setup pages. This allows you to enter cryogenic programmable
entries below zero if you have installed cryogenic hardware (optional
purchase). Additionally, SVE Valve allows volatile vapor to bypass the
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TRACE GC Ultra Configuration
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analytical column. Typically used with a large volume injector. If you have
the cryogenic hardware installed be sure that configurations have been set
manually into the TRACE GC Ultra using the TRACE GC Ultra keypad.
Solvent Valve
Column Select Valve
Check this box to use a split valve that is attached to the GC top. This
selection prevents condensation from reaching the split valve in a large
volume injection when using a PTV.
Check this box when using a column select valve with a single DPFC and
two inlets. The carrier gas diverts to the selected inlet that you activate.
Active Inlet
When you select Column Select Valve, specify which inlet you want to
exclusively use. When you activate an exclusive side, the other inlet side
defaults to no settings. Carrier gas diverts to the specified inlet.
Link to large volume assistant program
Checking this box allows you to use the Run Large Volume Program found
on the autosampler menu. However, it does disable other functions found on
other method editor pages (see the note below). This box is available only
after selecting LVOCI left inlet. Check this box only if you plan to use a
LVCI to run the Large Volume Program.
Checking this box disables the initial oven temperature controls in instrument
stup. This is because Large Volume Assistant Program sets the temperature
automatically. If you want to activate the initial oven temperature control on
te Oven page located in instrument setup, then uncheck this box.
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1.4 Detectors and Data Page
Use this dialog tab to configure the detectors you will use with your TRACE
GC Ultra. If you disconnect your detector from your GC, remember to
reconfigure your TRACE here and from the TRACE GC Ultra front panel.
Detectors chosen here display instrument setup pages and list in the Detector
Events located in the Run Table page.
Figure 1-4. Detector and Data Page
Configuration changes are stored with a method's configuration file. A
method uses the stored configurations so that a change in configuration
results in making the method incompatible. You will not be able to load a
method if it was created with a different configuration. Remember that you
can upload a method from the GC to save with the new method.
Detectors group box
Right
Select the detector type (None, FID, ECD, NPD, TCD, FPD, PID) installed
on your GC’s right inlet connection. The right side is as you are facing the
front.
Left
Select the detector type (None, FID, ECD, NPD, TCD, FPD, PID) installed
on the GC's left inlet connection. The left side is as you are facing the front.
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Auxiliary
Select the detector type (None, FID, NPD, FPD) installed on the GC's AUX
position.
Option Group Boxes
Detector Gas Flow
Control
Line Frequency
Configuration option for the Detector method editors. The default for this
check box is checked (on), in which case you get the detector method editor
controls with Flow text-edit controls. If you unselect this checkbox, then all
detector gas flow text-edit boxes in the detector method editors are removed
then you may check (on) or uncheck (off) the gas flow check boxes. In other
words, if this configuration option is on then you can turn detector gases on
and off and specify their flow rates in the text boxes. If this option is off then
you can only turn the gas flows on & off.
Select the AC power frequency (50 Hz or 60 Hz) that your GC is plugged
into. The line frequency control indicates allowable scan rate values.
Data Channel Definition Group Boxes
Channel 1 -3
1-14
Channels 1 through 3 are the data source connected to your TRACE GC
Ultra. Select the detector card position located nearest to the front of the GC
as Det-A. The detector card just behind Det-A is Det-B, and the detector card
closest to the rear of the GC is Det-C. Other data source connections include
Oven Actual, Oven % Power, Oven Exhaust % Open, Chassis Temp, and
Line Voltage.
Channel Name
Type a name for the channel’s data source displaying the chromatogram
during runtime. For example if you have an FID installed on the right
position of your TRACE GC Ultra type Right FID.
Scan Rate (Hz)
elect the number of data points to take per second during the acquisition.
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1.5 Auxiliary Page
These controls allow you to configure and use an auxiliary interface. Your
selections on this page directly influence the controls you will use on the Aux
Zones page located in the Instrument Setup window.Whatever configurations
you manually enter into your TRACE GC Ultra must exactly match what
controls you enter into this Auxiliary configuration dialog.
Figure 1-5. Auxiliary Page.
Aux Temperature Zones Group Box
• Check the Aux 1 Present control if you have one of these devices
attached: Aux1, Valve Oven , or MS Transfer Line
• Check the Aux 2 Present if you have one of these devices attached:
Aux 2 , Jet Separator, and Open Split
Aux Pressure Zones Group Box
• Check Aux 1 –3 Present controls if you will use auxiliary pressure
zones during your data acquisition.
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Oven Option Group Box
Check the Ultra Fast Module Present box if the UltraFast Module (UFM)
device is installed inside the GC.
See also UltraFast Module
UltraFast Module
The UFM is a GC device allows the direct heating of the analytical capillary
column properly installed inside the GC oven. The UFM device integrates a
GC capillary column with the components for its temperature control.
Compared to conventional air circulating oven, this device features faster
temperature programming.
Auxiliary Interface
An optional piece of equipment that must be used as the interface between
the GC and MS if carrier gas flow rates in excess of 4 mL/min through the
GC column are required for the chromatographic separation. This is true
when GC columns with inner diameters of 0.53 mm or larger are used. There
are two Auxiliary Interfaces available for use with the TRACE GC Ultra; a
jet separator and an open split .
Valve Oven
This is an independent heat zone, other than the analytical oven, where
valves are kept at a temperature to prevent analyte from condensing inside
them. Valves are often used in GC analysis for introducing sample into the
analytical column (sampling valve) or for enhancing the analytes separation
from other compounds in the sample matrix (column switching valve). Some
gas analyses require the use of two or more columns. The first column would
be used to hold some compounds while allowing others to pass on to a
second column for back-flushing to vent or for subsequent analysis. Valves
are mainly used in gas samples analysis; although liquid pressurized gas
samples may be analyzed using a liquid sampling valve. It is critical for the
valve or valves to be heated and to be in a purged in a closed environment
such as an oven, which prevents atmospheric gases from leaking into them.
This would apply to the gas sample analysis for the components that are in
air, such as oxygen or nitrogen.
transfer line
A heated tube that the GC column effluent passes through to enter the ion
source of the MS detector.
jet separator
An optional Auxiliary Interface available for use with the GCQ data system.
The jet separator is sometimes referred to as a momentum separator or an
enrichment device. A jet separator is used to reduce the flow of the column
effluent eluting from the GC column to a lower one that is compatible with
the vacuum system of the GCQ and TRACE.
A jet separator consists of two quartz jets that are separated by a small gap,
which is held under vacuum. The first jet is connected to the end of the GC
column where it receives the GC column effluent as it elutes from the
column. The second jet is connected to a piece of tubing (1/16 inch i.d.,
glass-lined stainless steel or 0.53 mm i.d. deactivated fused silica) that is
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connected to or passes through the transfer line of the GCQ. As the column
effluent exits the first jet it must jump across the gap into the second jet to be
transferred to the MS. Because the carrier gas has a low molecular weight, it
tends to diffuse (and its stream spreads out in space) as it exits the first jet;
thus, only a small percentage of the carrier gas makes it into the second jet.
Analyte compounds are of higher molecular weight than the carrier gas, and
do not spread out as much in space as they cross the gap. Thus, a higher
percentage of the analytes (relative to carrier gas) are able to cross the gap
into the second jet and move into the MS. This acts as a discriminatory split,
such that the flow volume is reduced but the analyte concentration is
enriched in the exiting gas stream.
See also: open split.
open split
An optional Auxiliary Interface . An open split interface is used to reduce the
flow of the column effluent eluting from the GC column to a lower one that is
compatible with the vacuum system of the TRACE GC Ultra. An open split
interface typically consists of a column transfer line with a mass
spectrometer transfer line placed near, or inserted into, that column transfer
line. The system may also use an additional makeup or purge gas for finer
flow control. The column transfer line is typically of a wider bore than the
mass spectrometer transfer line and as such, only a specific percentage of the
column effluent enters the mass spectrometer. This split is nondiscriminatory, that is, an approximately equal percentage of both sample and
carrier gas is split away from the mass spectrometer.
See also:jet separator.
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1.6 Road Map Home Page Status Tabs
Status pages for your TRACE GC Ultra are located on your Xcalibur
Roadmap-Home page. Just highlight TRACE GC Ultra from the Roadmap
Status tab scroll list and see the following pages (status, temperatures, flows,
and pressures) display the current GC status.
Status Tabs
Figure 1-6. Status Tabs
• Status
• Temperatures
• Flows
• Pressures
Status
General Group Box
Status:
1-18
Indicates if instrument is communicating to Xcalibur.
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Run Group Box
Elapsed time
Remaining time
The amount of time that has elapsed since the run started.
The amount of time that remains before the run finishes.
Emergency Conditions Group Box
Emergency shutdown
Your Xcalibur software automatically checks this box if an error condition
like a leaking hydrogen sensor or something is malfunctioning internally in
your TRACE GC Ultra. The software automatically shuts the TRACE GC
Ultra off. Check your TRACE GC Ultra Maintenance and Troubleshooting
Manual for possible solutions.
Over temperature
This box is checked only when Xcalibur software detects the temperature is
over the recommended level.
Shorted RTD
This detected problem requires certified technical support. Contact your local
TMQ Tech Support office for service.
Shorted oven RTD
This detected problem requires certified technical support. Contact your local
TMQ Tech Support office for service.
Temperatures page
These values show the actual and setpoint Temperature parameters for your
TRACE GC Ultra.
Flows page
These values show the actual and setpoint Flow parameters for your TRACE
GC Ultra.
Pressure page
These values show the actual and setpoint Pressure parameters for your
TRACE GC Ultra.
Keypad
Located in your Instrument Setup TRACE menu. Your Xcalibur virtual
TRACE GC Ultra Keypad operates just like if you were using it from the
TRACE GC Ultra front panel. The only difference is where you are pressing
the keys; from the instrument panel or your Xcalibur software. You might
find it helpful to learn the TRACE Keypad according to the following
groups:
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Action Keys:
Zone and Device
Information Keys:
Instrument Setup Keys:
Shortcut Keys:
Data Entry Keys:
Information Keys:
Method Storage and
Automation Keys:
Stop, Prep Run, and Start.
Oven, Left Inlet, Right Inlet, Left Detect, Right Detect, Aux, Left Carrier,
Right Carrier, Left Signal, Right Signal.
Leak Check, Column Eval, Config
Temp, Press, Flow, Time, Ramp #
On/Yes, No/Off, Mode/Type, ¥, Clear, Enter, st, 0-9
Status, Info/Diag, Run Log
Load, Store, Method, Seq, Edit/Active, Run Table, Clock Table, Auto
Sampler, Valves, Seq Control.
Look for specific instructions for operating each key in the TRACE GC Ultra
Operating Manual, Chapter 2.
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Chapter 2
TRACE Menu
This chapter describes the Instrument Setup menu.
This chapter contains these topics:
Menu Description
22
Using Flow Calculator
25
Using Vapor Calculator
31
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TRACE Menu
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2.1 Menu Description
The TRACE menu is located on the Instrument Setup-menu bar.
Figure 2-1. Menu
The pull-down mwnu contains the following options:
Send Method to GC command
Downloads the GC portion of the current method from the Instrument Setup
window to the gas chromatograph.
Get Method from GC command
Uploads the current method from the gas chromatograph to the Instrument
Setup Window.
Keypad
Located in your Instrument Setup TRACE menu. Your Xcalibur virtual
TRACE GC Ultra Keypad operates just like if you were using it from the
TRACE GC Ultra front panel. The only difference is where you are pressing
the keys; from the instrument panel or your Xcalibur software. You might
find it helpful to learn the TRACE Keypad according to the following
groups:
Action Keys
Zone and Device
Information Keys:
Instrument Setup Keys:
Shortcut Keys:
Data Entry Keys:
2-22
Stop, Prep Run, and Start.
Oven, Left Inlet, Right Inlet, Left Detect, Right Detect, Aux, Left Carrier,
Right Carrier, Left Signal, Right Signal.
Leak Check, Column Eval, Config
Temp, Press, Flow, Time, Ramp #
,
On/Yes, No/Off, Mode/Type, ∞ Clear, Enter, VW, 0-9
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Information Keys:
Method Storage and
Automation Keys:
Status, Info/Diag, Run Log
Load, Store, Method, Seq, Edit/Active, Run Table, Clock Table, Auto
Sampler, Valves, Seq Control.
Look for specific instructions for operating each key in the TRACE GC Ultra
Operating Manual, Chapter 2.
Flow Calculator
Column Flow Calculator allows you to make changes in non-DPFC
pneumatics, which affect carrier gas flow and velocity.
Additionally you may:
•
Change the column length, id (inner diameter), temperature, or inlet
pressure by moving any of the “Column Parameters slider bars will
change the calculated values for flow, velocity, and hold-up time.
(Changing outlet pressure or carrier gas type will also result in
recalculation of the carrier flow and velocity, but they are set on different
parts of the screen because they are less likely to be varied during
method development than the other column parameters.)
•
Change the “Carrier Gas Parameters slider bars for either flow or
linear velocity* will calculate the inlet pressure needed to give that flow
rate or velocity, keeping the other column parameters constant.
•
See the Flow, linear velocity, and hold-up time simultaneously when a
column parameter changes.
While all calculations are solved directly, calculating inlet pressure from
velocity (at greater than zero outlet pressure) is done using an approximation
technique.
For more information, refer to:
•
Using Flow Calculator
Vapor Calculator
Calculates the vapor volume for the PTV and SSL inlets from the injection
volume in proportion to the installed liner column. Assuming, if the vapor
behaves like an ideal gas and only solvent vapor needs to be considered for
dilute samples: vapor volume (V) for n solvent moles at temperature T and
pressure p is then approximated by the ideal gas law: V = nRT / p.
Absolute temperature and pressure are used for the calculations, and n is
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determined from the solvent volume, density, and molecular weight. Since 1
mole of an ideal gas occupies 22.4 liters at 0° C and 1 atmosphere pressure,
vapor volume in microliters can be calculated from the following equation:
V = [22.4 x ] [ r / MW] [(T + 273) / 273] [ patm / (pi + pa)] [Vinj]
where:
V = vapor volume, microliters, at inlet temperature and pressure
Vinj = solvent (liquid) volume, microliters injected
r= solvent (liquid) density, g/ml
MW= solvent molecular weight, g/mole
22.4= liters occupied by 1 mole of ideal gas at 0 °C and 1 atm pressure
T= inlet temperature, °C (absolute temperature = °K = °C + 273)
pi = inlet pressure, gauge (absolute pressure = pi + pa)
patm = 1 atm pressure (14.7 psi, 101 kPa, or 1.01 bar)
pa = ambient pressure, usually taken as patm for this approximation
Solvent boiling points, molecular weights, and densities can be found in
references such as the Handbook of Chemistry and Physics (CRC Press) and
the Merck Index (Merck & Co.).
For more information refer to:
2-24
•
Using Vapor Calculator
•
Comparing Vapor Volume to Liner Volume
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2.2 Using Flow Calculator
Use the Column Flow Calculator to determine column pressure settings and
flow rates through a capillary GC column when operating with manual
pneumatics. Column dimensions, temperature, inlet and outlet pressure, and
carrier gas type can be varied when calculating an outlet flow rate, average
linear velocity, and holdup time.
Column Flow Calculator Page
Figure 2-2. Column Flow Calculator Page
Column parameters group box
Each control listed in this box is affected by the choices made in the Carrier
Gas Parameters group box.
Length
Slide the slider bar to the desired column length in meters.
Inside diameter
Slide the bar to the columns inside diameter in millimeters.
Temperature
Slide the bar to the oven temperature you want to use (ºC).
Inlet pressure
Slide the bar to the pressure amount to supply to the column head (k).
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Column outlet pressure group box
1 Atm
Vacuum
Atmospheric pressure.
Select this if your TRACE is connected to a mass spectrometer.
Other
Select this if you want to adjust column outlet pressure above or below
atmospheric (0-43.5 psi)
Outlet Pressure
Slide the bar to the desired pressure amount the column flow will push
against at the column exit.
Carrier gas parameters group box
Gas type
Flow
Velocity
Holdup time
Select the type of gas you are using for column flow.
Actual flow calculated based on items listed in Column Parameter box.
This is the speed in which the flow travels to the column.
Time for non-retained peak to travel through the column. Hold-up time is
measured to determine the average linear velocity.
Using slider bar and buttons
Slider Bars
Click here to display the main topic for this procedure.
You might hear the slider bar referred to as a scroll bar. But whereas scroll
bars typically scroll vertically slider bar scroll horizontally. Use the slider bar
to adjust the displayed values.
Quick tips
• Grab (click and hold) the slider and drag it along the length of the
slider bar.
• Click on the arrow buttons on either end of the slider bars to increase
or decrease the associated value. The amount of increase or decrease
depends on the number of decimal places in the parameter, and will
vary for different slider bars.
• Click on the area between the slider and the arrow buttons to increase
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or decrease the slider bar’s associated value at 10 times the rate of
clicking on the arrows.
• Use your mouse or tab key to select a slider bar and then use the right
and left arrow keys located on your PC’s keyboard to adjust the values.
This method produces the same results as using the arrows.
Radio Button
Radio Butt
Use radio buttons to select one or several choices, however, only one radio
button from any group can be selected at the same time.
Reset Button
Click to reset all control parameters back to the factory settings. The only
parameters for which default values can be changed and saved are pressure
units (kPa, psi, or bar) and the controls listed in the Column Outlet Pressure
group box (1 atm, vacuum, other, and outlet pressure).
Done Button
Press Done to exit the screen. The pressure units and outlet pressure currently
selected save to disk and become the new defaults for the remaining work
session. Current pressure units (kPa, psi, or bar) and outlet pressure (1 atm,
vacuum, or outlet) settings save and load automatically when you open the
screen again. Values for all of the other parameters return to the factory
default settings.
Related Topics
For other details refer to
•
Pressure/Flow Calculations
•
Split Ratio Calculations
•
Average Linear Velocity
•
Vacuum Outlet Conditions
•
Other Pressures
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Pressure/Flow Calculations
The rate of carrier gas flow through an open tubular column can be calculated
using the well-understood relationships between pressure and flow in
capillary GC. These calculations are useful in your method development and
for you to determine the inlet pressure for a particular column and carrier
flow or the change in flow resulting from a temperature or pressure program.
The TRACE GC Ultra performs a column evaluation where the actual
column resistance is calculated. Thus, insuring and achieving accurate
column flows for a specific column length, i.d., and the wall coating.
Split Ratio Calculations
The split ratio for a capillary inlet is determined by the relationship between
the split vent flow and the column flow. Chromatographers calculate split
ratio in several ways and refer to this subject as: split flow/column flow,
column flow/split flow, or total flow/column flow. For these calculations,
split ratio is defined as
Split Ratio= SR1 = (split vent flow) / (column flow)
Split ratio is usually expressed as a ratio relative to one. For example, for a
split vent flow of 100 ml/min and a column flow of 2 ml/min,
SR1 = (split vent flow/column flow) : (column flow/column flow) = 50:1
On the pressure/flow calculator screen, the split ratio is always based on the
current value for column flow. Entering a value for either split vent flow or
split ratio and clicking on “Calc Flow/Ratio calculates the other.
Column Outlet Flow
The Poiseuille equation gives the gas flow carrier rate through an open
tubular GC column. For a given set of experimental conditions - column
length and id, carrier gas type, temperature, and outlet pressure - this
equation can be used to calculate the flow expected with a known inlet
pressure, or the pressure setting needed to give a desired flow rate.
F=outlet flow in ml/min, measured at Tref and pref(standard conditions)
= [ 60 p r / 16 h L ] [ (pi - po) / po] [ po / pref] [ Tref /T ](Eq. 1)
where:
r = column inner radius, cm
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L = column length, cm
pi = inlet pressure (absolute), dynes/cm
po = outlet pressure (absolute), dynes/cm
pref = reference pressure, typically 1 atm
T = column (oven) temperature, °K
Tref = reference temperature, typically 25 ° C (298 °K)
h= carrier gas viscosity at column temperature, poise
60 = conversion from seconds (cgs units) to minutes
Average Linear Velocity
The rate at which carrier gas moves through the GC column can also be
expressed in terms of its linear velocity. Because pressure on the carrier gas
changes at each point along the column, the gas will expand as it flows
through the column, and linear velocity will increase from the inlet to the
outlet. The retention time for a component reflects the average linear
velocity, which is measured by determining the elution time for an
unretained peak.
= average linear velocity at column temperature T, cm/sec=L / tM(Eq. 2)
where:
L= column length, cm
tM = hold-up time, elution time for an unretained component, sec
The average linear velocity is related to the outlet velocity by the
compression correction factor.
=uoxj
where:
j= compression correction factor (compressibility correction factor)
= 3 po (pi
- po ) / 2 (pi - po )
As with equation 1 for flow under a given set of experimental conditions, the
average linear velocity can be calculated from the column dimensions,
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viscosity, and pressure.
=[3r
/ 32 η L][ (pi
- po )
/( pi
- po )](Eq. 3)
Linear velocity is calculated here at oven temperature, to correspond with
retention time measurements. (Temperature does not appear explicitly in
equation 3, but the viscosity value is a function of temperature.)
Vacuum Outlet Conditions
With most GC detectors, pressure at the column outlet (po) is about 1 atm. In
GC/MS systems, however, the column outlet pressure is zero. This makes the
flow rate at outlet conditions very high, but column flow under reference
conditions can still be calculated from equation 1. (This corresponds to the
flow that would be measured with a flow meter connected to the discharge of
the vacuum pump, if such a measurement could be made). With po <<
pi , equation 1 becomes,
F = [ 60 π r / 16 η L] [pi
/ pref ] [ Tref /T](Eq. 4)
Other Pressures
There are some cases where the column outlet is neither at atmospheric
pressure nor under vacuum. One example is a column with a restrictor
installed at the end. This could be a length of narrow-bore tubing connected
to a mass spectrometer, as discussed in the topic Vacuum Outlet Conditions ,
or a splitter with connections to two different detectors.
Another example is in work with the atomic emission detector (AED), where
the cavity has a positive pressure of about 1.5 psig. When the total pressure
drop is low (that is., with short, wide-bore columns), this can cause a
significant difference between the calculated and actual flow values.
Selecting the “other setting for outlet pressure on the flow calculator allows
the appropriate value (14.7 + 1.5 = 16.2 psia) to be entered and used in the
calculations.
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2.3 Using Vapor Calculator
A liquid sample injected into a heated GC inlet rapidly vaporizes and
expands. Vapor Volume Calculator rapidly calculates the expansion volume
using several factors (solvent, injected liquid volume, temperature, and inlet
pressure). Included with this calculation is the resulting vapor expansion
volume relative to the inlet liner’s inner dimensions. Because, if the volume
of vapor is greater than that of the liner, the excess can expand into other
areas of the inlet and result in loss of sample or contamination of the gas
lines.
Vapor Calculator Page
Figure 2-3. Vapor Calculator Page
Inlet parameters group box
Injection volume
Temperature
Pressure gauge
Slide the bar to the volume amount to inject.
Slide the bar to the temperature your method calls for.
Slide the bar to the pressure amount your method calls for.
Vapor volume group box
Vapor Volume
An injected solvent’s calculated expansion volume. Compare this to a list of
the most frequently used liners and their available internal volume.
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If you are using an DPFC system, pressure programming can be used to help
control vapor volume. With the Pressure Pulse technique, pressure is briefly
increased at the time of injection, then returned to the setpoint best for
column flow rate during the rest of the run. Advantages for this technique
include:
Optimizing conditions for sample transfer to the column
•
•
•
Facilitating larger injection volumes
Reducing sensitive components residence time inside the inlet
Solvent parameters group box
Solvent parameters group box
Type
Select the solvent type you wish to use. Choosing a specific type
automatically sets preferred values in all the other fields. However, you still
may make adjustments. If any of your adjustments exceed the recommended
allowance for the liner, then Xcalibur displays an error message.
Values you see listed in Type are for the most common solvents that have
densities at 20° C. Select Other to calculate expansion volumes for other
solvents not listed here. Then you may enter the appropriate values for the
rest of the Solvent Parameters (boiling point, molecular weight, and density.)
Boiling Point
This is shown on the screen for reference, although it is not used in the
calculations. Because the approximation for vapor volume does not really
apply near the solvent boiling point, calculations are not done if the inlet
temperature is set within 20°C of this value. Instead, a message displays,
indicating that a higher temperature should be specified.
Density
For dense solvents with low molecular weights give the largest vapor volume
per microliter injected. The effects of inlet temperature and pressure on
vapor volume can also be seen from the equation - increasing temperature
increases volume, while increasing pressure decreases volume.
Mol. Weight
Molecular weight. The average mass of a molecule of a compound compared
to 1/12 the mass of carbon 12 and calculated as the atomic weights sum of the
constituent atoms. Or simply stated, the average mass of a molecule of a
compound expressed in atomic mass units (AMU).
Liner volume group box
Type
2-32
Select a liner type from the list box. Vapor Volume Calculator automatically
displays the Liner Volume
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Related Topics
•
Comparing Vapor Volume to Liner Volume
Comparing Vapor Volume to Liner Volume
Comparing vapor expansion volumes with liner volumes gives an estimate of
the sample volume that can be injected under different conditions. In
practice, mixing and diluting sample vapor with carrier gas during rapid
evaporation means that the actual volume occupied by vapor may be greater
than the calculated volume, and it depends on the liner design and how
rapidly carrier gas is moving through the inlet. A good starting point in
method development is to choose the liner, injection volume, temperature,
and pressure so that the vapor volume does not exceed the liner volume. (For
splitless injections, the liner volume should also be considered in choosing
the purge hold time, so that the inlet will be swept at least once by carrier gas
flowing onto the column.)
Typical volumes for capillary inlet liners have a range of 250 to 1000
microliters. Volume for an open liner can be calculated from the length and
inner diameter, but it may be reduced by internal constrictions or packing.
Rate of carrier gas flow at the column outlet, usually given as volumetric
flow in ml/minute. Because the volume for a given mass flow will depend on
temperature and pressure (pV=nRT), the conditions under which flow is
calculated or measured must be specified. See the section on “Column Outlet
Flow for details of the calculations.
Velocity, at which carrier gas moves through the column at temperature T, is
represented in cm/sec. Because pressure varies continuously along the
column (from pi to po), linear velocity also changes at each point between
inlet and outlet. The elution time for an unretained component provides a
measure of the average linear velocity. This is related to outlet velocity (and
flow) through the compression correction factor j.
See the topic on Average Linear Velocity for details of the calculations.
An unretained component's (at column temperature T) elution time is a
measure of time that sample components spend in the mobile phase. Hold-up
time is measured to determine the average linear velocity.
F = outlet flow in ml/min, measured at Tref and pref (standard conditions)
F = [ 60 p r / 16 h L ] [ (pi
- po ) / po] [ po / pref] [ Tref /T ](Eq. 1)
= average linear velocity at column temperature T, cm/sec
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=
L / tM
(Eq. 2)
Under a given set of experimental conditions, the average linear velocity can
be calculated from the column dimensions, viscosity, and pressure.
=[3r
/ 32 h L] [ (pi
- po )
/ ( pi
- po )](Eq. 3)
Flow can then be determined indirectly from the average linear velocity.
F
= [ 60 p r ] [Tref / T] [ 2( pi
- po ) / 3 pref (pi
- po )] (Eq. 4)
The equation used to calculate inlet pressure from velocity could be quite
slow under certain column conditions. At outlet pressures greater than
vacuum the equation cannot be solved directly. Instead, the equation is
solved by a successive approximation method. You can speed this process up
by using the flow slider bar to indirectly change the velocity value.
Electronic pressure control (EPC) provides an alternative to mechanical
pressure control for regulating the gas flow in your TRACE GC Ultra.
Additionally, EPC provides stability and precision in flow settings, which
makes it possible to use pressure/flow programming in GC methods and to
document pressures along with the other parameters.
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Chapter 3
Instrument Setup
This chapter contains the instructions to edit the TRACE GC Ultra
parameters according to the inlets and detector installed.
This chapter contains these topics:
Edit TRACE GC Ultra Parameters
36
Oven Page
38
UFM Page
42
SSL Page
45
OCI Page
49
HOTOC Page
51
LVOCI Page
53
PKD Page
58
PPKD Page
60
PTV Page
63
Carrier Page
68
ECD Page
77
FID Page
79
NPD Page
82
TCD Page
85
FPD Page
88
PID Page
90
Aux Zones Page
92
Run Table Page
94
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Instrument Setup
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3.1 Edit TRACE GC Ultra Parameters
Introduction
The parameters to set for the TRACE GC Ultra (oven, injectors and detector)
should be set according to your GC configuration.
All parameters can be sent to or loaded from the instrument connected by
using the functions available in TRACE Menu
To open this view:
1. Choose Instrument Setup from the Home Page window.
2. Click on the TRACE panel button located in the Instrument Setup
window.
Figure 3-1. Roadmap - Home Page
Using the TRACE Tabs
After you have configured the TRACE and options, you are ready to set the
controls to run your method.
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Related Topics
How To...:
•
Installing the Desolvation Column and Connecting the Tee
•
Characterizing Columns
•
Post Column Splitting of the GCQ with the Flame Ionization Detector
•
Operating an FID with Xcalibur Software
•
Simultaneous Analysis on the Ion Trap and the FID
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3.2 Oven Page
This page is the method editor for setting up parameters in the GC run.
To display this page: Click on the Oven page from the Instrument Setup view.
Figure 3-2. TRACE GC Ultra Oven Page View
Related topics:
•
Setting Up Oven Ramp Parameters
Oven Page Parameters
Oven Temperature Program graph
Graphical representations of the oven temperature program including any
post run events. The axes are temperature in degrees centigrade and time in
minutes. An isothermal run just gives a flat line
Oven Temperature Program Parameters
Ramps arrow buttons
3-38
Use the up-down control to add or subtract the number of ramps to use in the
oven temperature program. This is the rate in degrees Centigrade per minute
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the GC oven is ramped up or down from the initial temperature or the
previous level’s final ramp temperature. Clicking on the Down arrow
automatically adds a ramp level after the last one listed. Clicking on the Up
arrow deletes the highest level or the one being displayed on the bottom
Initial / Temp text box
The initial temperature the oven is set at the beginning of the temperature
program. For isothermal runs, this is the oven temperature for the entire run.
After Preready or Prep Run this is the temperature the oven will be at.
Checking the Link to Large Volume Assistant program located on the
Configuration»Inlet dialog disables this control. This is because you are able
to set these controls in the Large Volume Assistant program, which you will
find located in the autosampler menu. If you want to activate this control,
then uncheck the Link to Large Volume Assistant program located on the
Configuration»Inlet dialog box.
Initial / Hold Time text
box
The amount of time to maintain the initial temperature.
Ramp / Rate text boxes
The rate of change of the temperature when increasing the temperature from
one value to the next. Described in degrees Celsius per minute (°C/min). The
ramp begins at the previous step’s final temperature value and proceeds to the
current step’s final temperature at the specified rate.
Ramp / Temp text boxes
The temperature the oven is set at for the next ramp of the temperature
program. For isothermal runs, this is the oven temperature for the run. After
Preready or Prep Run this is the temperature the oven will be at.
Ramp / Hold Time text
boxes
The time to maintain the temperature specified in the Final Value control
box.
Oven Group Box
Oven Subambient
check box
This refers to an installed subambient (additional purchase), which allows
subambient oven cooling.
Max Temp text box
Specify the maximum temperature for this run. The GC has a maximum
temperature of 450°. The maximum allowable temperature for the column
being used in the method is automatically set.
PrepRun Timeout
Specify how long the GC should remain in the Ready to Inject mode before
returning to Stand By. If the GC Start button is not pressed within the prep
run timeout period, then the GC will return to Stand By mode. This feature is
a protective measure to keep the GC from being in the Ready to Inject mode
too long. For example, this will prevent accumulation of contaminants on the
analytical column when doing splitless injections.
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Equilibration Time (min)
text box
Specify how much time the GC should wait after the initial conditions are
met before going to standby.
Acquisition Time Group Box
Use Oven Run Time
radio button
Use Other Time button
and text box
Check this box for the Acquisition Time to be the same as the oven run time;
however this does not include the post-run time.
You can define the time for acquisition. Enter a value in the text box.
Post Run Conditions check box and group box
Use this option to specify post run conditions. When you select the Post Run
Conditions check box, the group box becomes active.
Temperature text box
The post-run temperature setpoint. Use as a bakeout to clean up the column
or use as a cool down phase after the run has finished.
Time text box
The amount of time the oven remains at the post-run temperature setpoint.
Pressure text box
The post-run pressure setpoint for the left and right EPC inlet. Setting Up
Oven Ramp Parameters
Setting Up Oven Ramp Parameters
Set oven ramp parameters
1. Open the Instrument Setup window.
2.
Display the Oven page by clicking on the TRACE panel button.
3. Type in the temperature (degrees Celsius) and time (in minutes) for the
initial oven parameters.
4. To add ramps to the oven temperature program, click on the down arrow
of the up-down control. If you add too many ramps, click on the up arrow
to delete them.
Set post run conditions
Select the Post Run Conditions check box and enter the time, temperature
and pressure parameters.
1. To keep the default analysis time, check the Total Run Time box. If you
want to set a different analysis time, leave the Total Run Time box
unchecked and enter a value for the analysis time.
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2. Select Oven Subambient (if your system has this option) for subambient
cooling.
3. Enter the Max Temp and Equilibration Time values.
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3.3 UFM Page
This page is the method editor for setting up parameters in the GC run.
To display this page: Click on the UFM page from the Instrument Setup
view.
Figure 3-3. UFM Page View
Related topics:
•
Setting Up UFM Ramp Parameters
UFM Page Parameters
UFM Temperature Program Graph
UFM Temperature
Program graph
Graphical representations of the column temperature program. The axes are
temperature in degrees Centigrade and time in minutes. An isothermal run
just gives a flat line.
Block Temperature Group Box
Temperature
3-42
Enter here the temperature of the auxiliary heating block.
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UFM Temperature Program Parameters
Ramps arrow buttons
Use the up-down control to add or subtract the number of ramps to use in the
column temperature program. This is the rate in degrees Centigrade per
minute (°C/min) the column is ramped up or down from the initial
temperature or the previous level’s final ramp temperature.
•
Clicking on the Down arrow automatically adds a ramp level after the
last one listed.
•
Clicking on the Up arrow deletes the highest level or the one being
displayed on the bottom.
Initial / Temp text box
The initial temperature the column is set at the beginning of the temperature
program.
Initial / Hold Time text
box
The amount of time to maintain the initial temperature.
Ramp / Rate text boxes
The rate of change of the temperature when increasing the temperature from
one value to the next. Described in degrees Centigrade per minute (°C/min).
The ramp begins at the previous step’s final temperature value and proceeds
to the current step’s final temperature at the specified rate.
Ramp / Temp text boxes
The temperature the column is set at for the next ramp of the temperature
program.
Ramp / Hold Time text
boxes
The time to maintain the temperature specified in the Final Value control
box.
Oven Group Box
Prep Run Timeout
Specify how long the GC should remain in the Ready to Inject mode before
returning to Stand By. If the GC Start button is not pressed within the prep
run timeout period, then the GC will return to Stand By mode. This feature is
a protective measure to keep the GC from being in the Ready to Inject mode
too long. For example, this will prevent accumulation of contaminants on the
analytical column when doing splitless injections.
Max Temp text box
Specify the maximum temperature for this run. The UFM has a maximum
temperature of 350 °C.
Equilibrium Time (min)
text box
Specify how much time the GC should wait after the initial conditions are
met before going to standby.
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Acquisition Time (min) Group Box
Use Oven Run Time
radio button
Use Other Time button
and text box
Check this box for the Acquisition Time to be the same as the UFM device.
You can define the time for acquisition. Enter a value in the text box.
Setting Up UFM Ramp Parameters
Set UFM ramp parameters
1. Open the Instrument Setup window
2. Display the UFM page by clicking on the TRACE panel button.
3. Type in the temperature (degrees Centigrade) and time (in minutes) for
the initial column parameters.
To add ramps to the column temperature program, click on the down
arrow of the up-down control. If you add too many ramps, click on the up
arrow to delete them.
Set block temperature parameter
1. Set the temperature of the column auxiliary heating
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3.4 SSL Page
This page is the method editor for the Split/Splitless inlet.
To display this page: Click on the SSL page from the Instrument Setup view.
Figure 3-4. S/SL Page View
Related topics:
•
Setting Up Parameters for Split Mode
•
Setting Up Parameters for Splitless Mode
•
Setting Up Parameters for Splitless with Surge Mode
SSL Page Parameters
SSL Modes list box
Use this spin box to select one of the following:
Split
The carrier flow is split in the injection port with the bulk going out the split
vent. Use this injection type when analyzing high concentration or neat
samples, or in instances where sensitivity is less important. The split vent
remains open all the time. This method yields the sharpest peaks, if the split
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gas is properly mixed. Additionally, this technique can improve peak shape
and resolution.
Splitless
Splitless w/surge
The split vent is closed during the injection to drive most of the sample into
the column. Solvent effect is required to refocus the analytes , especially
more volatile components. You can achieve solvent effect by keeping the
analytical column or guard column near the sample's solvent boiling point.
This technique also requires the spilt valve be opened after the injection to
prevent band broadening due to solvent flooding. Splitless times of ~ 1
minute are typical.
A surge is applied during the splitless time to reduce residence time of the
analytes in the inlet. This will reduce band broadening and may sharpen
peaks, especially for more volatile components, which are not improved by
cold trapping effects on the column. Usually this technique involves an oven
temperature ~ 50C° below BP of analyte.
Inlet Group Box
Temperature check box
and text box
The setpoint for the inlet's temperature. Depending on the mode of injection,
it should be set at a temperature appropriate to vaporize the sample and
solvent.
Split Flow check box
and text box
Specify the total split flow coming out of the inlet. This is the total flow out
of the inlet when the split valve is open.
Split Ratio text box
Splitless Time text box
The ratio of split vent flow to the column flow. Calculate the split ratio as
shown: Split Ratio = (column flow + split vent flow) / (column flow).
The amount of time after the injection at which the split vent opens.
Purge group box
This group controls the septum purge for the inlet. Septum purge is used to
sweep the bottom of the septum to reduce contamination from sample
analytes. This prevents carryover from run to run Septum purge also
prevents contamination of the inlet from septum bleed.
Constant Septum Purge
check box
The septum purge may be turned off during a splitless injection. Checking
this box will keep the septum purge valve open continuously. By leaving this
box unchecked, the analyst may close this valve during the injection splitless
time.
Stop Purge Time text
box
Enter the time (in minutes) for the septum purge valve to close after
beginning the injection. The Constant Septum Purge checkbox has to be
unchecked for this option to be used. This is usually set to the same time as
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the splitless time.
Surge Pressure
The pressure applied during the splitless time to produce a surge of flow in
the inlet to speed transfer of the sample. It may be used, depending upon the
analysis, to sharpen peaks closer to the solvent’s boiling point where cold
trapping is ineffective and solvent effect is the main refocusing mechanism.
Try adding 8 psi or 55.157 kPa to the inlet and observe early peaks after the
solvent to see if peak tailing is reduced.
Surge Duration
The amount of time a pressure surge is administered after the injection.
Typically, set to coincide with the splitless time.> GC Setup View - Split
Mode
Setting Up SSL Parameters
Setting Up Parameters for Split Mode
Use the following procedure to specify the carrier gas flow rate and pressure
for constant flow.
1. Open the Instrument Setup window.
2. Click on the TRACE GC Ultra panel button.
3. Select the SSL tab.
4. Choose Split from the Mode list box.
If you would like to set a temperature for the injector, click in the temperature
check box and enter a temperature value (in degrees Celsius) in the
Temperature text box.
Setting Up Parameters for Splitless Mode
Use the following procedure to specify parameters for a splitless GC run.
1. Open the Instrument Setup window.
2. Click on the TRACE GC Ultra panel button.
3. Select the SSL tab.
4. Choose Splitless from the Mode spin box.
If you would like to enter a temperature for the injector, click in the
temperature check box, then enter the desired temperature in the temperature
text box.
If you would like to enter a split flow, click in the Split Flow check box and
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enter a value (mL/min) in the Split Flow text box.
5. Enter a value in the Splitless time text box.
If you want to use constant septum purge, click in the Constant Septum Purge
check box. Otherwise, enter the time in minutes in the Stop Purge Time
textbox.
Setting Up Parameters for Splitless with Surge Mode
Use the following procedure to specify the carrier gas flow rate and pressure
for ramped pressure.
1. Open the Instrument Setup window.
2. Click on the TRACE GC Ultra panel button.
3. Select the SSL tab.
4. Choose Splitless w/ surge from the Mode list box.
If you would like to enter a temperature for the injector, click in the
temperature check box, and enter the desired temperature in the temperature
text box.
If you would like to enter a split flow, click in the Split Flow check box and
enter a value (mL/min) in the Split Flow text box.
5. Enter a value in the Splitless time text box.
If you want to use constant septum purge, click in the Constant Septum Purge
check box. Otherwise, enter the time in minutes in the Stop Purge Time text
box.
6. Enter values in the Surge Pressure and Surge Duration text boxes.:
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3.5 OCI Page
This is the method editor for the on-column inlet.
To display this page: Click on the OCI page from the Instrument Setup view.
Figure 3-5. On Column Page View
Related topics:
•
Setting Up Parameters for an OCI
OCI Page Parameters
Sec. Cooling Time text box
The amount of time the secondary cooling stays on after the start of injection.
This begins when the TRACE GC Ultra display-panel displays READY. The
value you enter in this text box is the time duration for secondary cooling,
after selecting Run Start. For example, if you enter a one in this text box, then
secondary cooling and the secondary valve turn on when the GC begins
READY mode and remains on for one minute after the GC run has started.
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Setting Up Parameters for an OCI
1. Open the Instrument Setup window.
2. Click on the TRACE GC Ultra panel button.
3. Select the OCI tab.
4. For secondary cooling enter a value equivalent to the sample injection
time.
5. If you have auxiliary purge controls available and the optional hardware
is installed, then select column purge to continuously purge the inlet
during injection.
6. If constant purge is not selected, then enter a Stop Purge Time value that
is greater than the sample injection time.
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3.6 HOTOC Page
This page is the method editor for the high oven cold on-column inlet.
To display this page: Click on the HOTOC page from the Instrument Setup
view.
Figure 3-6. HOTOC Page View
Related topics:
•
Setting Up Parameters for an HOTOC
HOTOC Page Parameters
Inlet Group Box
This group box is intentionally left blank for future developments.
HOTOC Group Box
HOTOC Temperature
check box and text box
Activates the secondary cooling valve and prevents the GC from going into
READY mode until the entered temperature value you enter in this box is
achieved.
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Duration text box
Enter the amount of time the secondary cooling remains on once the GC
advances to READY.
SVE Valve Group Box
These controls display ONLY if you selected SVE Valve during Inlet
configuration.
SVE Temperature check
box and text box
The solvent vapor exit valve is normally heated to a temperature above the
boiling point of the solvent being injected, in order to prevent solvent
condensation in the valve, which may cause a flow change during injection.
Allowable values are 0-200 ºC or On/Off.
SVE Duration text box
This is the time that the SVE valve is open after injection to vent most of the
solvent’s large volume. The LVI program usually calculates this parameter
since the exact time to cut off is critical for the LVI injection to properly
operate. This time determines the volume of residual solvent that is allowed
to enter the analytical column.
Setting Up Parameters for an HOTOC
Click here to display the main topic for this procedure
1. Cool the area around the column where sample is introduced, since the
GC column oven generally heats to a temperature higher than the
injected solvent’ boiling point. Generally this temperature is set to a
value below a solvents boiling point.
2. Set the HOTOC Time Duration to the same amount of time as it takes for
a sample injection.
3. If the SVE Valve is installed, heat it to approximately 150 ºC. Turn on the
SVE Valve for the necessary time needed to vent the solvent. Solvent
vent valve turns on when GC READY begins. After RUN START the
SVE duration time turns off. However, this duration time stays on until
the required amount of solvent is vented. It is necessary that the GC run
be started at the beginning of sample injection.
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3.7 LVOCI Page
This is the method editor for the large volume on-column inlet.
To display this page: Click on the LVOCI page from the Instrument Setup
view.
Figure 3-7. LVOCI Page View
Related topics:
•
Setting Up Parameters for an LVOCI
•
Operating Precautions for the LVOCI
•
Tips for Performing Large Volume Injections
LVOCI Page Parameters
Inlet Group Box
Sec. Cooling Time text
box
This is the time after injection that the secondary cooling air (or other cooling
fluid, for example N2 or CO2 s on. Allow the cooling to be on long enough to
allow the liquid injection to move away from the syringe needle tip before
the syringe is withdrawn. After the syringe is withdrawn, this cooling is no
longer necessary.
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LVI Evaporation Group Box
Pressure text box
This is the inlet pressure used during the evaporation stage of the large
volume injection. This parameter is usually generated by the LVI software
program, and not entered by the user. This can be the same as inlet pressure,
if a single pressure program is being used, and this entry will be grayed out.
Allowable values are 0-250 or 0-700 kPa, depending on the carrier flow
module.
Duration text box
Enter a duration time for the injection’s LVI evaporation stage. This
parameter is usually calculated by the LVI software and transferred into this
page.
SVE Valve Group Box
Temperature check box
and text box
The solvent vapor exit valve is normally heated to a temperature above the
boiling point of the solvent being injected, in order to prevent solvent
condensation in the valve, which may cause a flow change during injection.
Allowable values are 0-200 ºC or On/Off.
SVE Duration text box
This is the time that the SVE valve is open after injection to vent most of the
solvent’s large volume. The LVI program usually calculates this
parametersince the exact time to cut off is critical for the LVI injection to
properly operate. This time determines the volume of residual solvent that is
allowedto enter the analytical column.
Setting Up Parameters for an LVOCI
Setting up parameters for an LVOCI method is a three-step process:
configuring instruments for LVI, calculating optimum parameters and then
downloading parameters to the autosampler and GC. Mass spectrometer
parameters download with the GC.
Configuring for LVI
1. Configure the autosampler, TRACE or TOP GC, and MS for LVOCI.
2. Open the autosampler method editor and create a new method for the
LVI method.
3. Configure your autosampler to use the Large Volume Program. Select
Left for the Autosampler Placement and Large Volume and enter the
maximum volume for the syringe that is installed. Select OK. The system
configures for EPC gas control for the left LVI injector.
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Calculating Optimum Parameters
When using the TRACE GC Ultra:
1. Select the left carrier and set the flow mode to constant flow or
programmed pressure with vacuum compensation.
2. Next, select LVOCI and select Temperature On. Enter 200°C for the SVE
valve temperature to prevent residue accumulating from the solvent
during desolvation.
3. Enter the required ramped pressure setting for downloading the two
pressures that the LVI software calculates for the two step process of
desolvation and then analyte analysis. The first pressure is high for
solvent evaporation andthe second pressure setting is lower for analytes
enhanced resolution throughthe capillary column.
Note: Do not enter the oven ramps for the analysis at this time; they are entered
after loading the parameters for the LVI. You may also setup parameters for isobaric
operations.
When using the GCQ Plus Mass spectrometer:
1. Press the mass spectrometer icon button. Select the first line for the first
segment and double click the left mouse button. The dialog box for the
MS opens. Enter the appropriate values and set the start time to 5.0
minutes or longer. You will have a residual amount of solvent going
through the detector and want to delay the filament ignition until after
this solvent has passed through. Select a time that provides detection of
the first analyte but not the solvent
2. ook at the fore-pressure (located on the homepage Status page) during
the first run to verify the time for the solvent to pass out of the mass
spectrometer. The fore pressure may be monitored during filament delay.
3. Save the method.
4. Set the mass spectrometer to a high-pressure operation mode by selecting
the CI mode from the GCQ Plus front panel.
Downloading LVI Parameters into the GC Method
1. From Instrument Setup, click on the autosampler icon. The autosampler
menu displays on the menu bar, which contains two selections necessary
to run a large volume injection select Run Large Volume Program and
the Load Large Volume File.
2. Select Run Large Volume Program to begin creating a LVI method
file. For step-by-step instructions on how to create LVI method files, just
click the Help button listed in the LVI dialog box. Be sure to save the file
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with a specific name and close the LV program.
Run Large Volume
Program
Launches the large volume program to automatically make a Large Volume
File which calculates the appropriate oven temperature, injection speed and
pressure setting required for desolvation and analysis.
3. Select Load Large Volume File to see a list of available methods. Select
the appropriate method. The instrument parameters for the large volume
injection insert into the GC and autosampler methods accordingly.
Load Large Volume File
Actually downloads the file made during the Run Large Volume Program.
4. Enter the desired oven program, analytical column flow required, other
autosampler and mass spectrometer parameters.
5. Enter a long filament delay for the first injection for 5-8 minutes. The
actual fore pressure to the mass spectrometer may be monitored during
the filament delay. Just look at the GCQ Plus Status page located on the
home page for desolvation step optimization and filament delay time.
Operating Precautions for the LVOCI
To conserve air consumption, install a step-down single stage regulator to use
secondary coolant set at 10 psi or 70 kPa. Stop all sequence runs not using
secondary coolant and do not have a vial located in the tray. This is because
the GC begins using initial conditions when not using secondary coolant
andwill stop the run when it does not detect a vial in the autosampler tray.
Set the GCQ Plus to the CI mode (press the GCQ Plus EI/CI button
locatedon the GCQ front panel) to operate in high pressure mode.
Tips for Performing Large Volume Injections
Read the LVI Manual.
• Select the smallest retained volume when optimizing your large
volume injection method. You can choose larger retained volumes if
the smallest amount is not adequate.
• During the filament delay process, the GCQ extends the filament delay
until adequate vacuum has been detected (the blue blinking light on the
front panel of the GCQ-MS will turn off and the green light will be
on). This is completely normal. You can increase your filament delay
time in the MS method to match the actual time it takes for the vacuum
system to recover from the large volume injection.
• Get the best pressure value results by using the LVI Assistant program
to select the Injected Volume option. Then use the LVI calculated
pressure values to download to the instruments.
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• Before loading an LVI method from the AS method editor, make sure
the GC is configured for pressure program mode. This will download
the pressure values from the LVI optimization program and ensure that
the correct times and flows are present to evaporate the solvent from
the pre-column. Using the constant-flow or constant-pressure modes
results in too much flow into the mass spectrometer during the run
analysis. Using programmed flow will cause too little flow to be
present during the desolvation period, overloading the vacuum system
of the mass spectrometer.
• Some parameters will be grayed out in the GC and autosampler
method parameter after downloading the LVI method. These values
are calculated and automatically set by the LVI software.
• If you are using a TRACE GC Ultra, check to see that the initial
pressure time is equal to the inject time plus the SVE delay time. You
may need to change this manually.
• If you are using a CE 8000 Top, and you note residual solvent in the
background spectrum throughout the run, shorten the fused silica line
on the SVE valve. For injection of 100 uL of Hexane, remove 15 cm.
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3.8 PKD Page
This page is the method editor for the packed column inlet.
To display this page: Click on the PKD page from the Instrument Setup view.
Figure 3-8. PKD Page View
Related topics:
•
Setting Up Parameters for PKD
PKD Page Parameters
Inlet Group Box
Temperature check box
and text box
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This is the temperature setting for the packed column (PKD) inlet. The
allowable entry range is 30-400 ºC. This temperature is usually selected to be
20º above the evaporation temperature for all components of interest in the
analysis sample. Optimum temperature for an analytical method varies with
he method and sample requirements. The entry also has a check box for on/
off values, so that the temperature setting may be turned off without
affectingthe setpoint (usually used for troubleshooting purposes.)
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Setting Up Parameters for PKD
1. Set up parameters for the temperature.
Typically, you set the inlet temperature to approximately 20 ºC above the
temperature necessary to volatilize a sample’s components of interest.
ThePKD operates in a closed loop flow control manner. This means that the
carrier-gas-flow-module measures the flow of gas to the inlet for direct
flowcontrol. Typical gas flow rates for 1/8 PKDs are 15-30 cc/min.
Note: Operating this inlet with micro packed or wide-bore capillary columns make
it necessary to optimize the carrier gas flow to match the installed column.
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3.9 PPKD Page
This is method editor for the purge packed column inlet.
To display this page: Click on the PPKD page from the Instrument Setup
view.
Figure 3-9. PPKD Page View
Related topics:
•
Setting Up Parameters for PPKD
PPKD Page Parameters
Inlet Group Box
Temperature check box
and text box
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This is the temperature setting for the purged-packed column (PPKD) inlet.
The allowable entry range is 30-400 ºC. This temperature is usually selected
to be 20º above the evaporation temperature for all components of interest in
the analysis sample. Optimum temperature for an analytical method varies
with the method and sample requirements. The entry also has a check box for
on/off values, so that the temperature setting may be turned off without
affecting the setpoint (usually used for troubleshooting purposes.)
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Purge Group Box
Constant Septum Purge
check box
This entry allows the septum purge flow to be turned off for a specified
amount of time after injection. Allowable entries is On or Off. If you select
On using a needle to penetrate to a normal injection depth then you will see
little sample loss.
Stop Purge Time text
box
If the constant septum purge box is unchecked, specify the time after
injection that the septum purge flow is turned off. Keep the flow off for the
minimum time amounts so those septum bleed products are not transferred
onto the analytical column. Typical entries are 0.2-1.0 minutes, with
allowable entries from 0-99.99 minutes.
Surge Group Box
Surge Pressure text box
This control is enabled when you select wide bore/w surge or packed/w surge
as the injection mode. This injection mode allows a higher inlet pressure to
be applied during injection. This serves to reduce the volume of the vapor
cloud created when injected sample is vaporized, and may improve separated
analytes resolution. Allowable entries are 0-250 or 0-700 kPa, depending on
the carrier-flow-module you have installed.
Surge Duration text box
Enter a time-duration for the inlet pressure to be set at the surge pressure
setting. This entry should be only the time necessary to ensure the injected
sample transfers to the analytical column; so that the column flow is slightly
affected.
Mode
Wide Bore mode
The PPKD inlet operates in both packed mode and wide bore (capillary)
column mode. If you select wide bore, the carrier flow module operates like
conventional capillary modes, and uses the column evaluation K-factor to
calculate flow from pressure applied to the inlet. This mode is appropriate for
capillary column’s length equal or greater than 30 m and operating at column
flow rates less than 5 mL/min. When a column’s length is less than 30 m, the
flow resistance is so small that the packed mode, with its closed loop flow
control is more accurate.
Packed mode
If packed mode is selected for the PPKD inlet to operate in then the column
flow control is in a closed loop. This means that the carrier module is directly
measuring the column flow. This mode is useful for a short (< 30m) wide
bore capillary column (0.53 mm or >) as well as packed columns. These
column usually operate at flow rates > 5 cc/min, so that direct column
measurement is feasible. Column evaluation is not performed for this mode.
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Wide Bore w/Surge
mode
This selection allows you to program a higher inlet pressure during the
sample injection. This reduces the vaporized sample volume and enhances
the injection vapor cloud transfer onto the column in a narrow time window.
Thus, yielding a better component resolution by the column.
Packed w/Surge mode
This selection allows you to program a higher inlet pressure during the
sample injection. This reduces the vaporized sample volume and enhances
the injection vapor cloud transfer onto the column in a narrow time window.
Thus, yielding a better component resolution by the column. Setting Up
Parameters for PPKD mode
Setting Up Parameters for PPKD
1. Select the desired operation mode: Wide Bore Packed mode , Wide Bore
w/Surge , or Packed w/Surge mode .
2. Go to the Inlet group box and select Temperature.
3. Go to the Purge group box and select Constant Septum Purge or Stop
Purge Time .
If you selected any mode w/surge then go to the Surge group box. Enter the
desired parameters into the Surge Pressure control and the Surge Duration
control.
The PPKD inlet may be operated in two primary modes: wide bore or
packed. In wide-bore mode, the inlet operates like a direct capillary inlet.
Column flow is not measured directly, but is calculated from inlet pressure,
oven temperature, and a measured k-factor. The k-factor is automatically
measured by the TRACE GC Ultra in the column evaluation process and
represents a summation of selected factors (such as the carrier gas type,
outlet pressure, column resistance versus pressure, and others).
In packed mode, the carrier flow module measures the column flow. This
mode is appropriate for packed column and short wide bore (< 30 m and >
.53 mm i.d.) columns. These short columns do not provide enough resistance
to flow to allow measurement of k-factors for typical capillary column
control.
As a general rule, the inlet must provide column carrier gas flow control,
andvaporize the injected samples for transfer to the analytical column.
Because the proper temperatures and flow are sample and method dependent,
noguidelines are available.
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3.10 PTV Page
This is the method editor for the programmable temperature vaporizing
inlet.This is a right inlet only. Several controls require purchasing additional
TRACE GC Ultra options.
To display this page: Click on the PTV page from the Instrument Setup view.
Figure 3-10. PTV Page View
Related topics:
•
Setting Up Parameters for PTV
PTV Page Parameters
Mode list box
Select a PTV mode from the Mode list box .
PTV Modes
All PTV injection modes are programmable ramped temperatures you
operate at varying temperatures with specified times and temperature
increments. Selecting PTV modes activates various controls listed the
Injections Phases group box.
PTV Split
The carrier flow is split in the injection port with the bulk going out the split
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vent. Use this injection mode when analyzing high concentration or neat
samples, or in instances where sensitivity is less important. The split vent
remains open all the time. This method yields the sharpest peaks if the split
gas is properly mixed.
PTV Splitless
The split vent is closed during the injection to drive most of the sample into
the column. The solvent effect is required to refocus the analytes, especially
more volatile compounds. You can achieve the solvent effect by keeping the
analytical column or guard column slightly below the solvent's boiling point.
Splitless times of ~ 1 minute are typical. Activates controls listed in the Purge
group box.
PTV Solvent Split
Injection technique used when it is necessary to eliminate the solvent before
the sample enters the column. This is mainly for large volume injections
when components have a lower volatility than the solvent. This item does not
list if the Solvent Valve control was selected in for PTV in the Inlet
Configuration dialog.
PTV Large Volume
Displays when the Solvent Valve control is selected or the PTV in the Inlet
Configuration dialog. Activates Purge controls.
CT Modes
All CT injection modes are constant temperature (isothermal) modes you
operate at set temperatures and time increments. Selecting CT modes
disables all controls in the Injections Phases group box.
CT Split
Constant temperature (isothermal) split valve. Isothermal temperatures
operate at a single temperature during the entire analysis.
CT Splitless
Constant temperature (isothermal) splitless valve. The split vent is closed
during the injection to drive most of the sample into the column. The solvent
effect is required to refocus the analytes, especially more volatile
compounds. You can achieve the solvent effect by keeping the analytical
column or guard column slightly below the solvent's boiling point. Splitless
times of ~ 1 minute are typical. Activates controls listed in the Purge group
box.
CT Splitless w/Surge
Constant temperature (isothermal) activates controls listed in the Surge group
box. Same as CT Splitless but can also program a surge during an injection.
Surge starts at Prep Run and continues until the surge duration time is
finished. Surge is further defined in the Surge Group Box.
Inlet Group Box
Temperature checkbox
and text box
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Allowable entry ranges are 30-400 ºC. However, if you selected the SVE
Valve in the Inlet Configuration dialog then you can enter cryogenic
temperature values (below 0 ºC) in the range –50º to 400º.
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For non-cryogenic use, this temperature is usually set for 20º above the
evaporation temperature for the sample’s components of interest. Optimum
temperature for an analytical method varies with the method and sample
requirements. The entry also has a check box for on/off values, so that the
temperature setting may be turned off without affecting the setpoint (usually
used for troubleshooting purposes.)
Split Flow checkbox
and text box
Split Ratio
Splitless Time text box
Solv. Valve Temp
Specify the total split flow coming out of the inlet. This is the total flow out
of the inlet when the split valve is open.
The ratio of split vent flow to the column flow. Calculate the split ratio as
shown: Split Ratio = (column flow + split vent flow) / (column flow). You
must select the PTV Split or CT Split mode to use the Split Ratio control.
Then select the Carrier page and select Constant or Programmable Pressure
mode to activate the Split Ratio control.
The amount of time after the injection at which the split vent opens.
This control activates only after selecting SVE Valve from the Inlet
Configuration dialog (see Inlets Page). Check this box to enter a
temperature value for a PTV large volume injection instead of the PTV
solvent. With this control you can regulate the temperature for the PTV largevolume heating valve.
Purge Group Box
Constant Septum Purge
checkbox
This entry allows the septum purge flow to be turned off for a specified
amount of time after injection. Allowable entries is On or Off. If you select
On using a needle to penetrate to a normal injection depth then you will see
little sample loss.
Stop Purge Time text
box
If the constant septum purge box is unchecked, specify the time after
injection that the septum purge flow is turned off. Keep the flow off for the
minimum time amounts so those septum bleed products are not transferred
onto the analytical column. Typical entries are 0.2-1.0 minutes, with
allowable entries from 0-99.99 minutes.
Surge Group Box
Surge Pressure text box
This control is enabled when you select wide bore/w surge or packed/w surge
as the injection mode. This injection mode allows a higher inlet pressure to
be applied during injection. This serves to reduce the volume of the vapor
cloud created when injected sample is vaporized, and may improve separated
analytes resolution. Allowable entries are 0-250 or 0-700 kPa, depending on
the carrier-flow-module you have installed.
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Surge Duration text box
Enter a time-duration for the inlet pressure to be set at the surge pressure
setting. This entry should be only the time necessary to ensure the injected
sample transfers to the analytical column; so that the column flow is slightly
affected.
Injection Phase group box
Injection
Use this control for the injection’s ramped pressure. Available only with PTV
Splitless or PTV Large Volume mode. The injector temperature is
automatically set to be lower than the solvent’s boiling point all you have to
do is specify the time the injector temperature must be maintained.
Evaporation
This group of controls allows you to specify solvent evaporation controls:
pressure (PTV Splitless and PTV Large Volume only), rate, temperature, and
time in minutes. Set the solvent evaporation temperature, set the rate to reach
the solvent evaporation temperature.
Transfer
This group of controls allows you to specify controls for the sample transfer
into the column: Pressure (PTV Splitless and PTV Large Volume only), rate,
temperature, and time in minutes. Specify the pressure if available. Set the
rate in ºC/s to reach the sample transfer temperature. Set the temperature for
sample transfer into the column. Set the time in minutes for the transfer
temperature to be maintained.
Cleaning
Set the rate necessary to reach the cleaning temperature. Set the injector
cleaning temperature. Set the time in minutes the cleaning temperature must
be maintained.
Options Group Box
Start here. Selections made in this group box determine which controls to
activate in other group boxes.
Sub-ambient
Evaporation Phase
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Select this option to enter sub-ambient temperatures (–50 ºC to 400 ºC) in the
Temperature text box.
Check this box to activate the Evap controls listed in the Injection Phases
group box.
Ramped Pressure
If you selected the PTV Splitless or PTV Large Volume mode then this
control is available for you to activate pressure controls for solvent injection,
evaporation, and transfer.
Cleaning Phase
Check this box to activate the Cleaning controls listed in the Injection Phases
group box.
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Setting Up Parameters for PTV
1. In the Options group box, select an injection mode and then check or
uncheck the available controls listed in this group box.
2. Set the available controls listed in the Injection Phases group box.
3. Set the available controls listed in the Inlet group box.
4. Set the available controls listed in the Purge group box.
5. Set the available controls listed in the Surge group box.
6. For PTV mode or SSL inlets and all isothermal modes select Vapor
Calculator from the TRACE menu bar to automatically calculate the
expansion volumes.
7. Select Keypad from the TRACE menu bar for quick access to your
TRACE GC Ultra keypad functions.
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3.11 Carrier Page
This page is the method editor for setting the carrier gas for the TRACE GC
Ultra inlet. Carrier is gas used as the mobile phase in gas chromatography.
The carrier gas carries the analyte mixture through the GC column, where it
is separated into its individual components. The carrier gas flows through the
GC column at a specific rate, measured either as a linear velocity (cm/sec) or
as a flow rate (mL/min). Common carrier gases are helium, hydrogen, and
nitrogen. Hydrogen offers the best chromatographic properties (optimum
resolution at the highest flow rates). However, because hydrogen is
flammable, helium is often used as an alternative for a carrier gas.
To display this page: Click on the Carrier page from the Instrument Setup
view.
Figure 3-11. Carrier Page View
Related topics:
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•
Setting Up Parameters for Constant Flow Mode
•
Setting Up Parameters for Constant Pressure Mode
•
Setting Up Parameters for Programmed Flow Mode
•
Setting Up Parameters for Programmed Pressure Mode
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Flow Mode list box
The controls you see on this page are dependent on the Flow Mode selection.
Please select one of the following modes and jump to that topic for detailed
information.
•
Constant Flow Mode
•
Constant Pressure Mode
•
Programmed Flow Mode
•
Programmed Pressure Mode
Four flow modes are available and affect the controls listed in the Ramps
group box:
Constant Flow — controls in the Ramp group box display Flow (cc/min).
Enter a column flow for the analytical column. When using an oven
temperature program, run the GC to automatically increase the pressure
constant flow on the column. This compensates a gas's increased viscosity
due to an increase in temperature. In this mode, the inlet pressure is varied
during an analytical run as needed to maintain the column flow at a specified
setpoint. This means that when a column is heated and its restriction to flow
increases the inlet pressure is increased.
Constant Pressure — controls in the Ramp group box display Pressure.
Enter inlet pressure for the analytical run. In this mode, a specified pressure
is applied to the column and remains unchanged throughout the analysis.
Programmed Flow — controls in the left group box display Ramps, Rate,
Flow, and Hold Time. Enter program to control column flow for analytical
run.
Programmed Pressure — controls in the left group box display Ramps,
Rate, Pressure, and Hold Time. Enter inlet pressure program for analytical
run.
In both the programmed flow and programmed pressure modes, the flow or
pressure changes according to a timetable similar to temperature
programming. The analyst may specify an initial pressure, initial time up to
three program ramps with rates, targets, and hold times for each needed
ramp. The programmed modes are typically used to shorten analysis times by
increasing column flow to drive higher boiling components off the column
faser at the end of analysis.
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Constant Flow Mode
Click on the Carrier tab of the GC Setup view, and then click on Constant
Flow in the Flow Mode list box
Use the Carrier page, constant flow option to select a constant flow without
ramping.
The parameter available are:
Flow Program graph
A graphical representation of a flow program for the carrier gas. It is a flat
line if a constant flow program is selected. The axes represent time for the xaxis and flow in mL/min for the y-axis.
Flow text box
A flow for the analytical column. For an oven temperature programmed run
the GC automatically increases pressure to keep a constant flow on the
column compensating for increased viscosity of gas due to increase in
temperature.
Vacuum Compensation check box
Check this box to compensate for a vacuum at the end of the analytical
column. This is usually the case where the detector is a mass spectrometer.
When the box is not checked calculations are made for a normal GC detector,
which is usually at atmospheric or slightly higher pressure.
Gas Saver check box and group box
This group box contains gas saver controls, which reduce carrier gas
consumption, especially when a large split flow is used. The gas saver
options are set to come on at some point well after the injection to conserve
gas. Checking the box will activate the other two features of gas saver.
Gas Saver Flow text box
The desired flow after the injection or in standby. Gas saver flow displays the
carrier gas in milliseconds and minutes until the end of the run.
Gas Saver Time text box
The time after the injection when gas saver flow will be activated.
Constant Pressure Mode
Click on the Carrier tab of the GC Setup view, and then click on Constant
Pressure in the Flow Mode list box.
Use the Carrier page with constant pressure option to select a constant
pressure for the analysis. The parameters are:
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Pressure Program
graph
The graph represents a pressure program for the carrier gas. It is a flat line if
a constant pressure program is selected. The axes represent time for the xaxis and either flow in mls/min or pressure in kPa for the y-axis.
Pressure text box
Enter the inlet pressure for the analytical run in this text box.
Vacuum Compensation check box
Check this box to compensate for a vacuum at the end of the analytical
column. This is usually the case where the detector is a mass spectrometer.
When the box is not checked calculations are made for a normal GC detector,
which is usually at atmospheric or slightly higher pressure.
Gas Saver check box and group box
This group box contains gas saver controls, which reduce carrier gas
consumption, especially when a large split flow is used. The gas saver
options are set to come on at some point well after the injection to conserve
gas. Checking the box will activate the other two features of gas saver.
Gas Saver Flow text box
The desired flow after the injection or in standby. Gas saver flow displays the
carrier gas in milliseconds and minutes until the end of the run.
Gas Saver Time text box
The time after the injection when gas saver flow will be activated.
Programmed Flow Mode
Use the Carrier page, programmed flow option to set up a programmed flow
for the GC. The available parameters are:
Use the Carrier page, programmed flow option to set up a programmed flow
for the GC. The available parameters are:
Ramps arrow buttons
The controls in the Ramps group box depend on the Flow Mode you choose.
Use the up-down control to add or subtract the number of ramps to use in the
pressure or flow program. This is the rate of change in mL/min that the
column flow is increased or decreased. Click the down arrow to add another
ramp level. Click the up arrow to delete the last ramp displayed.
Initial / Flow text box
The initial flow for the inlet and column at the start of the analytical run.
Initial / Hold Time text
box
The amount of time the flow is held at the beginning of the run before the
first ramp.
Ramp / Rate text boxes
The rate of change in mL/minute that the columns flow is increased or
decreased.
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Ramp / Flow text boxes
Ramp / Hold Time text
boxes
The amount of flow to be used for each ramp.
The amount of time the flow is held at the end of the ramp. Setting Up
Parameters for Programmed Flow Mode
Vacuum Compensation check box
Check this box to compensate for a vacuum at the end of the analytical
column. This is usually the case where the detector is a mass spectrometer.
When the box is not checked calculations are made for a normal GC detector,
which is usually at atmospheric or slightly higher pressure.
Gas Saver check box and group box
This group box contains gas saver controls, which reduce carrier gas
consumption, especially when a large split flow is used. The gas saver
options are set to come on at some point well after the injection to conserve
gas. Checking the box will activate the other two features of gas saver.
Gas Saver Flow text box
The desired flow after the injection or in standby. Gas saver flow displays the
carrier gas in milliseconds and minutes until the end of the run.
Gas Saver Time text box
The time after the injection when gas saver flow will be activated.
Programmed Pressure Mode
Click on the Carrier tab of the GC Setup view, and then click on
Programmed Pressure in the Flow Mode list box
Use the Carrier page, programmed pressure option to program the pressures
to the carrier. The parameters are:
Ramps arrow buttons
The controls in the Ramps group box depend on the Flow Mode you choose.
Use the up-down control to add or subtract the number of ramps to use in the
pressure or flow program. For pressure programs, this is the rate of change in
kPa per minute that the inlet pressure increased or decreased. Click the down
arrow to add another ramp level. Click the up arrow to delete the last ramp
displayed.
Initial / Pressure text
box
The initial pressure for the inlet and column at the start of the analytical run.
Initial / Hold Time text
box
The amount of time the pressure is held at the beginning of the run before the
first ramp.
Ramp / Rate text boxes
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The rate of change in pressure that the ramp is intended to reach.
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Ramp / Pressure text
boxes
Ramp / Hold Time text
boxes
The pressure to be applied during injection and at the beginning of the ramp.
The time to maintain the value in the ramp/pressure field.
Vacuum Compensation check box
Check this box to compensate for a vacuum at the end of the analytical
column. This is usually the case where the detector is a mass spectrometer.
When the box is not checked calculations are made for a normal GC detector,
which is usually at atmospheric or slightly higher pressure.
Gas Saver check box and group box
This group box contains gas saver controls, which reduce carrier gas
consumption, especially when a large split flow is used. The gas saver
options are set to come on at some point well after the injection to conserve
gas. Checking the box will activate the other two features of gas saver.
Gas Saver Flow text box
The desired flow after the injection or in standby. Gas saver flow displays the
carrier gas in milliseconds and minutes until the end of the run.
Gas Saver Time text box
The time after the injection when gas saver flow will be activated.
Setting Up Parameters for Constant Flow Mode
Use the following procedure to set up parameters for the constant flow
option.
1. Open the Instrument Setup window.
2. Select the Carrier tab.
3. Check the On box in the Flow group box to turn on the flow.
4. Type in a value for the flow for the analytical column.
5. Check the Vacuum Compensation box to compensate for a vacuum at the
end of the analytical column.
When the box is not checked calculations are made for a normal GC
detector, which is usually at atmospheric or slightly higher pressure.
6. Check the Gas Saver box to activate gas saver controls. Checking the box
will activate the other two features of gas saver:
Gas Saver Flow (mL/min): The desired flow after the injection or in
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standby. Gas saver flow displays the carrier gas in milliseconds and
minutes until the end of the run.
Gas Saver Time (minutes): The time after the injection when gas saver
flow will be activated.
Setting Up Parameters for Constant Pressure Mode
Use the following procedure to set up parameters for constant pressure.
1. Open the Instrument Setup window:
2. Select the Carrier tab.
3. Check the pressure box to enable flow to the inlet. When this box is not
checked gas flow goes to the inlet and through any installed column. If
the oven is taken to a high temperature, the column may be damaged as
well as any detectors or components attached to it.
4. Enter a value for the pressure for the analytical column.
5. Check the Vacuum Compensation box to compensate for a vacuum at the
end of the analytical column.
6. When the box is not checked calculations are made for a normal GC
detector, which is usually at atmospheric or slightly higher pressure.
7. Check the Gas Saver box to activate gas saver controls. Checking the box
will activate the other two features of gas saver:
Gas Saver Flow (mL/min): The desired flow after the injection or in
standby. Gas saver flow displays the carrier gas in milliseconds and
minutes until the end of the run.
Gas Saver Time (minutes): The time after the injection when gas saver
flow will be activated in the Instrument Setup window.
Setting Up Parameters for Programmed Flow Mode
Use the following procedure to set up parameters for the Programmed Flow
option.
1. Open the Instrument Setup window.
2. Select the Carrier tab.
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3. Select Programmed Flow from the Flow Mode spin box.
4. Check the Flow box to enable flow to the inlet.
When this box is not checked gas flow goes to the inlet and through any
installed column. If the oven is taken to a high temperature, the column
may be damaged as well as any detectors or components attached to it.
5. Type in values for the initial flow and hold time for the analytical
column.
6. Use the Ramp control to add extra ramps to the program.
7. Enter rate, flow, and hold time values for each additional ramp in the
program.
8. Check the Vacuum Compensation box to compensate for a vacuum at the
end of the analytical column.
When the box is not checked calculations are made for a normal GC
detector, which is usually at atmospheric or slightly higher pressure.
9. Check the Gas Saver box to activate gas saver controls. Checking the box
will activate the other two features of gas saver:
Gas Saver Flow (mL/min): The desired flow after the injection or in
standby. Gas saver flow displays the carrier gas in milliseconds and
minutes until the end of the run.
Gas Saver Time (minutes): The time after the injection when gas saver
flow will be activated.Related topics:
Setting Up Parameters for Programmed Pressure
Mode
Use the following procedure to set up parameters for the Programmed
Pressure option.
1. Open the Instrument Setup window.
2. Select the Carrier tab.
3. Select Programmed Pressure from the Flow Mode spin box.
4. Check the Pressure box to enable flow to the inlet.
When this box is not checked gas flow goes to the inlet and through any
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installed column. If the oven is taken to a high temperature, the column
may be damaged as well as any detectors or components attached to it.
5. Type in values for the initial pressure and hold time for the analytical
column.
6. Use the Ramp control to add extra ramps to the program.
7. Enter rate, pressure, and hold time values for each additional ramp in the
program.
8. Check the Vacuum Compensation box to compensate for a vacuum at the
end of the analytical column.
When the box is not checked calculations are made for a normal GC
detector, which is usually at atmospheric or slightly higher pressure.
9. Check the Gas Saver box to activate gas saver controls. Checking the box
will activate the other two features of gas saver:
Gas Saver Flow (mL/minute): The desired flow after the injection or in
standby. Gas saver flow displays the carrier gas in milliseconds and
minutes until the end of the run.
Gas Saver Time (minutes): The time after the injection when gas saver
flow will be activated.
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3.12 ECD Page
This page is the method editor for the electron capture detector.
To display this page: Click on the ECD page from the Instrument Setup view.
Figure 3-12. ECD Page View
Related topics:
•
Setting Up Parameters for ECD
ECD Parameters
Detector group box
Base Temperature
This is the ECD detectors base body temperature in degrees Celsius (300º to
350 ºC).
ECD Temperature
The temperature of the Electron Capture Detector in degrees Celsius. Select
a temperature above the final oven temperature and high enough to prevent
sample condensation inside the detector. The ECD temperature heats
separately from the base temperature. Typical operating temperatures for the
ECD are 300º to 350 ºC.
Reference Current
The amount of current in nano Amps applied as reference current to the
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detector. Sometimes referred to as standing current. The value entered here is
the current for the detector to maintain at a constant level. The settings for
this current depends on the type of detector used with the ECD. Values from
0-3 nano Amps may be entered. Changes in this value may effect linearity.
See the TRACE GC Ultra Operators Manual for more detailed information.
Pulse Amplitude
Pulse Width
The voltage applied to the detector. Consult your ECD Detector manual for
more detailed information. Values from 5 V to 50 V may be entered.
Typically the pulse amplitude is set to 50 V. However, very clean systems
may operate equally as well at 25 V or 15 V. This voltage is used to aid in
achieving the selected reference current or standing current. Detectors
exhibiting line out frequencies below 1-2 kHz should be operated at 25 V or
15 V.
Select from 0.1, 0.5, or 1 microseconds to control the pulse going to the
detector. The use of Nitrogen as make-up requires 1 ms pulse. Use of Argon/
Methane requires a 0.1 ms pulse to produce the highest linear range. The
value selected depends on the type of detector gas being used with the ECD.
Nitrogen requires a pulse width value of 0.5 or 1.0. Usually 1.0 is the desired
value.
Flow (mL/min) Group Box
Makeup
Specify how much make-up gas (0-90 cc/min) to activate. Nitrogen or
Argon/Methane is suggested as the make-up gas to the ECD detector.
Checking this box enables the use of make-up gas into the detector. To
reduce line out time, use higher flow rates around 60 mL/min when the
detector is first turned on. Reduce the makeup to 30 mL/min for
optimumresults.
Setting Up Parameters for ECD
1. .Set the detector base temperature to 250 ºC
2. Set the ECD temperature to 300 ºC.
3. Set the Reference Current to 1 nA
4. Set the Pulse Width to 1 µ sec.
5. Set nitrogen makeup gas at 30-40 mL min.
Allow several hours for the system to line out. The detector frequency should
stabilize below 5 kHz.
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3.13 FID Page
Note: For auxiliary, right, and left usage only.
This page is the method editor for the flame ionization detector.
If you are using a stacked detector and using an ECD, then the makeup gas is usually
plumbed separately for the ECD, and is specified as the Electron Capture medium.
This page is the method editor for the electron capture detector.
To display this page: Click on the FID page from the Instrument Setup view.
Figure 3-13. FID Page View
Related topics:
•
Setting Up Parameters for FID
FID Parameters
Detector Group Box
Flame On
Checking this box turns on the detector gases if not previously on, and turns
on the ignition coil to light the flame. Unchecking this box shuts off the
detector gases, extinguishing the flame.
Performs several functions: turns on detector gases, increases hydrogen flow
above the setpoint to 40 mL/min, decreases air below the setpoint to
approximately 200 mL/min, turns the makeup gas off, supplies current to the
ignition coil.
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Base Temperature
Flameout Retry
Ignition Threshold
This is the temperature in degrees Celsius of the detector base body. Enter
values 250º to 350º. To prevent stationary phase condensation on the
analytical column, operate the detector at a higher temperature than the oven
program. Pay special attention to the analytical column’s upper limit.
Use this to monitor the signal. If the signal should drop below the Ignition
Threshold , it will turn on the ignition coil and attempt to light the FID.
Flameout Retry repeats up to three times. Flameout Retry compares the
ignition threshold value to the signal pA.
The point at which the FID attempts to re-ignite. The signal in picoamps for
the GC to use to compare the current signal to determine if the FID flame is
still lit. If the signal pA is lower than the threshold the FID flame function
indicates igniting When the flame ignites the signal pA increases above the
ignition threshold and the ignition process stops. If the signal pA does not
increase above the ignition threshold value, the flame function attempt to
ignites the FID three times and then stops. The flame function indicates out.
Flow (mL/min) Group Box
Checking any of the following controls enables gas flow from the DGFC to
the detector. Checking any of these boxes and downloading the method will
turn on the particular gas even if the Flame On box is not checked.
Air
Specify how much airflow (0-600 cc/min) to activate. Acceptable values are
On/Off. When the air is turned on, enter the value of the air supplied to the
detector to optimize the flame. Typical flow is 350 mL/min.
H2
Specify how much Hydrogen flow (0-200 cc/min) to activate. Acceptable
values are On/Off. When the Hz is turned on, enter the value of Hydrogen to
supply to the detector to optimize the flame. Typical flow is 25 mL/min.
Makeup
Specify how much makeup gas (0-90 cc/minute) to activate. Nitrogen is
recommended as the makeup gas to the FID detector. Acceptable values are
On/Off. Makeup gas enhances FID sensitivity. Typical flow is 30 mL/min.
Signal Group Box
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Range (nA)
The range for the detector signal to be acquired. Selections are 1, 10, 100,
100 however, the lowest setting, 0, gives the most sensitivity. A higher range
may be needed for high concentration samples. Range represents the amount
of current required in nano amps from the detector to offer a full-scale output
at the selected range.
Analog Filter
Electronic filtering used to reduce baseline noise. Acceptable values are On/
Off. The analog filter applies a time constant to the analog output reducing
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the response times to high frequency baseline noise thus filtering the analog
output.
Setting Up Parameters for FID
1. Check the FID base temperature check box.
2. Check the base temperature box and set the temperature to 250 ºC.
3. Turn on the detector gas settings to: H2 = 30 mL/min, Air=350 mL/min,
Makup=30 mL/min.
4. Turn the flame on.
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3.14 NPD Page
Note: Use in Auxiliary, right, and left detector positions.
This page is the method editor for the nitrogen phosphorus detector.
To display this page: Click on the NPD page from the Instrument Setup view.
Figure 3-14. NPD Page View
Related topics:
•
Setting Up Parameters for NPD
The Nitrogen-Phosphorus detector detects Nitrogen and or Phosphorus
containing organic compounds.
The NPD source is a ceramic bead impregnated with alkali metal. The
source is mounted just above the jet with air, makeup and a dilute
concentration of hydrogen combined with the column effluent. The source is
heated to high temperature producing plasma around the bead, which
decomposes the sample. Interaction with the thermionic source is thought to
produce the ions attracted and detected by the collector. A low hydrogen
flow (< 4mls/min) is used which will not sustain a flame. An NPD (Nitrogen/
Phosphorus Detector), is an alkali-sensitized thermionic detector used for the
specific detection of phosphorus and organic nitrogen. The NPD is very
sensitive and is instrumental in pesticide and herbicide residue analysis in
various EPA methods. This detector is also useful for the clinical analysis of
caffeine, nicotine, and other nitrogen-containing drugs.
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NPD Parameters
Detector Group Box
Source Current
Specify the current amperes necessary to generate a background current.
Base Temperature
This is the temperature in degrees Celsius of the detector's base body.
Maximum range is 450 ºC. Typically detectors that use the detector base
temperature as the sole source of heat are set to 300 ºC. Of course the
detector base temperature should always be at least 10 ºC higher than the
maximum column oven operating temperature. Detectors that have a
secondary heat source require a base temperature of typically 250 ºC.
Polarization Voltage (v)
Select a polarization voltage (1.0-9.9) to apply to the collector. Polarizing
voltage is a DC voltage that is superimposed on to the NP source assembly.
Adjust the polarizing voltage from 1.0 to 9.9 in .1 V increments.
Flow (mL/min) Group Box
Checking any of these boxes activates the gas flow from the DGFC module
to the detector and downloads the method to turn on the particular gas.
Air
NPD H2
H2 Delay
Makeup
Specify how much airflow (60-100 µL/min) to activate. When the air is
turned on, enter the value of the air supplied to the detector to optimize the
flame. Typical flow is 70 mL/min.
Specify how much hydrogen air flow (2-4 cc/min) to activate. Acceptable
values are On/Off. When the H2 is turned on, enter the hydrogen range (0-10
mL/min) to supply to the detector, which optimizes the flame. Typical flow is
3 mL/min.
Specify how many minutes to delay the H2 flow within the detector.
Specify how much makeup gas (10-30 µL/min) to activate. Nitrogen is
recommended as the makeup gas to the NPD detector. Makeup gas has less
thermal capacity and tends to cool the plasma and bead less. Makeup gas
serves to sweep the column effluent into the detector energy field on plasma.
Makeup should be nitrogen since Helium tends to cool the source. Typical
makeup flow is 15 mL/min.
Signal Group Box
Range (nA)
The range for the detector signal to be acquired. Selections are 1, 10, 100,
100 however, the lowest setting, 0, gives the most sensitivity. A higher range
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may be needed for high concentration samples. Range represents the amount
of current required in nano amps from the detector to offer a full-scale output
at the selected range.
Analog Filter
Check this box to enable electronic filtering, which reduces the response to
high frequency baseline noise and signal.
Setting Up Parameters for NPD
1. In the Detector group box, set the Source Current to 2.720 or as required
to generate a background current. Set the Base Temperature to 300 ºC.
Set the Polarization Voltage to 3.5.
2. In the Flow group box, set the Air to 7.0. Set the H2 to 3.0. Set the H2
delay to how many minutes you want to wait before starting the
hydrogen flow. Set the Makeup gas to 15.
3. In the Signal group box, set the Range to the desired sensitivity. Check
the Analog Filter box if you want to reduce the response to high
frequency noise and signal.
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3.15 TCD Page
This page is the method editor for the thermal conductivity detector.
To display this page: Click on the TCD page from the Instrument Setup view.
Figure 3-15. TCD Page View
Related topics:
•
Setting Up Parameters for TCD
TCD Parameters
Detector Group Box
Block Temperature
Sets the TCD cell temperature. Enter an integer between 30 and 450 ºC.
Typical temperature is 200 ºC depending on the application you are using. A
general rule to apply is to set the temperature to a higher value than the
maximum temperature reached by the GC column oven during the analysis.
See Recommended Filament Temperature and Voltages .
Transfer Temp.
Enter an integer between 20 and 400 ºC. This temperature heats the transfer
line between the GC oven and the TCD cell. We recommend setting a value
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higher than or equal to the set oven temperature.
Filament Power
Check this box to turn on power to the TCD filaments.
Constant Filament
Temperature
Check this box to activate the Filament Temperature control only and
disables Filament Voltage and Fil. Max Temperature controls. This operating
mode keeps a constant filament temperature based on the relationship
between the block temperature and the filament temperature and carrier gas.
When using low thermal conductivity gases the filament temperature is high
for low voltage supply. See Recommended Filament Temperature and
Voltages .
Filament Temperature
Enter an integer between 50 and 450. Adjust in 10 º increments. Filament
temperatures should be kept at least 20 ºC higher than the block temperature .
The greater the difference the better the sensitivity. However, the useable
difference between the block temperature and the filament temperature
depends on the carrier gas you are using. See the TRACE GC Ultra
Operators Manual for suggested carrier gas values and the TCD.
See also TCD Recommended Filament Temperature and Voltages
Filament Voltage
Enter an integer between 5 and 15 in 1 V increments. Filament voltages are
closely related to filament temperature values. Typical values are 5 to 7 V.
See TCD Recommended Filament Temperature and Voltages
TCD Recommended Filament Temperature and Voltages
Table 3-1.
Detector Temperature 100 ºC
Table 3-2.
Voltage (v)
5
6
7
8
315
355
9
10
395
435
Table 3-3.
Filament Temperature
235
275
The detector’s block temperature and filament temperatures, voltages, and
carrier gas influence the analysis sensitivity and filament’s average life-time.
Fil. Max. Temperature
Limits the filament temperature when the detector operates in the constant
voltage mode. Enter an integer between 50 to 450 ºC. See Recommended
Filament Temperature and Voltages.
Flow (mL/min) Group Box
Makeup
3-86
Makeup indicates the make-up gas flow rate. Enter an integer between 0 and
100. If the value is less than or equal to 10 mL/min, the filament power is
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disabled.
Reference
Set the appropriate reference gas flow. Enter an integer from 1 to 100. If the
value is less than or equal to 10 mL/min, the filament power is disabled.
Reference gas is used in addition to the sample’s carrier gas to measure the
gas conductivity when sample moves across both filaments. Reference gas
must be same type of carrier gas and use the same flow rate.
Signal Group Box
Gain
Negative Polarity
Set the gain to x1 or x10. When a x10 gain is selected the GCs sensitivity
increases the detector output signal and electrical and mechanical noise
amplification.
Select this control to reverse the polarity output signal as a TC carrier gas
function versus the sample and the analytical column (channel right or hannel
left) used.
Setting Up Parameters for TCD
These steps are typical parameters for analyzing samples using Helium as a
carrier gas.
1. In the Detector group box, select Block Temperature and enter 150.
Select Transfer Temp and enter 150. Check the Constant Filament
Temperature box to turn the filament power on. Enter 250 in the Filament
Temperature text box.
2. In the Flow group box select Makeup if you are using makeup gas. Select
Reference if you need to set a reference gas flow.
3. In the Signal group box, set the Gain ifyou need amplified sensitivity.
Select Negative Polarity to reverse the TC gaspolarity.
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3.16 FPD Page
Auxiliary usage only.
This page is the method editor for the flame photometric detector.
To display this page: Click on the FPD page from the Instrument Setup view.
Figure 3-16. FPD Page View
Related topics:
•
Setting Up Parameters for FPD
FPD Parameters
Detector Group Box
Flame On
Base Temperature
FPD Temperature
PMT Voltage
3-88
Select this control to turn the detector ignition and detector gases on.
Select to set the detector base body temperature. For an FPD set at 250 ºC.
Sets the detector cell temperature. A typical operating temperature is 180 ºC.
Sets the value for the dynode voltage to apply to the photo-multiplier table.
Values are high and low. Low set the voltage to –800 V and high sets the
voltage to –900 V.
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Flow (mL/min) Group Box
Air
Adjusts the air supply to the detector. Typical values are 200 mL/min.
H2
Adjusts the hydrogen gas supply to the detector. Typical value is 150 mL/
min.
Makeup
Adjusts the makeup gas to the detector. Preferred gas type is Nitrogen and a
typical setting is 30 mL/min.
Signal Group Box
Range
Analog Filter
Changes the electrometer gain. Valid selections are 1, 10, and 100. With 1
yielding the most sensitivity.
Electronic filtering used to reduce baseline noise. Acceptable values are On/
Off. The analog filter applies a time constant to the analog output reducing
the response times to high frequency baseline noise thus filtering the analog
output.
Setting Up Parameters for FPD
1. In the Detector group box, set the Base Temperature to 250 ºC. Set the
FPD Temperature to 180 ºC. Set the PMT Voltage to low. Optional:
Flame On.
2. In the Flow group box, set the Air to 200 ºC. Set the H2 to 150 ºC. Set the
Makeup gas to 30 ºC.
3. Optional: In the Signal group box, set the Range and Analog Filter.
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3.17 PID Page
This page is the method editor for the photoionization detector.
To display this page: Click on the PID page from the Instrument Setup view.
Figure 3-17. PID Page View
Related topics:
•
Setting Up Parameters for PID
PID Parameters
Detector Group Box
Lamp On
Base Temperature
Lamp Current
3-90
Turns the UV lamp power on, which strikes the lamp and thus creates a lamp
current.
Turns the detector base body temperature on.
Selects the PID lamp current. Valid selections are low and high. The higher
the lamp current the more intense the transmitted lamp transmission, which
enhances sensitivity, but reduces lamp life.
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Flow (mL/min) Group Box
Makeup
Sheath Gas
Turns on the makeup gas. Typical value is 15 mL/min.
Flows around the outside of the cell to reduce temperature. Typical flow
value is 30 mL/min.
Signal Group Box
Range
Analog Filter
Changes the electrometer gain. Valid selections are 1, 10, 100, 1000. With
one yielding the most sensitivity.
Electronic filtering used to reduce baseline noise. Select On or Off. The
analog filter applies a time constant to the analog output reducing the
response times to high frequency baseline noise thus filtering the analog
output.
Setting Up Parameters for PID
1. In the Detector group box, set the Base Temperature to 180 ºC. Set the
Lamp Current to low. Optional selections: Lamp On.
2. In the Flow group box, set the Makeup gas to 15-20 mL/min. Set the
Sheath Gas to 20-30 mL/min.
3. In the Signal group box, set the Range to X1. Optional selections:
Analog Filter.
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3.18 Aux Zones Page
Ths page is the method editor for the setting auxiliary connections.
All selections on this page must exactly match the settings you have
manually entered into your TRACE GC Ultra and the TRACE GC Ultra
detector configuration window. See Detectors and Data Page.
To display this page: Click on the Aux Zones page from the Instrument Setup
view.
Figure 3-18. Aux Zones Page View
Related topics:
•
Setting Up Parameters for Aux Zones
Aux Zones Parameters
Aux Pressure Zones Group Box
When you check one of these boxes (Aux 1 or Aux 2) you let the GC know
you have an auxiliary heater.
Set a temperature from 0-450. If any of these pressure channels (Aux 1-3) are
connected to your TRACE GC Ultra, then check the box and enter a value
from 0-700 kPa.
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Setting Up Parameters for Aux Zones
1. Make sure that auxiliary configurations are selected in the TRACE GC
Ultra Configuration program.
2. Check either Aux 1 or Aux 2 in the Aux Temperature Zones box and then
enter a temperature value of 0-450.
3. Check if any of these pressure channels are present (Aux 1, Aux 2, or
Aux 3) controls located in the Aux PressureZones box and then enter a
temperature value of 0-700kPa.
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3.19 Run Table Page
This page is the method editor to program events to happen before or during
a run. For example, a valve could open two minutes into a run. Listed in the
run table page are settings entered prior to the run in the Run Time Event
dialog. Time, item, and settings display in this run table. Controls listed in
the Initial Values group box are for switching external devices On/Off.
To display this page: Click on the Run Table page from the Instrument Setup
view.
Figure 3-19. Run Table Page View
Related topics:
•
Setting Up Parameters for Run Table
•
Using the Add/Event Run-Time Event Dialog
Run Table Parameters
Time, Item, and Settings
3-94
Time
Displays which Event Time (Prep run or Run Time) was selected in the Run
Time Event dialog.
Item
Displays which event (Detector, Valve, or External) was configured in the
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Run Time Event dialog.
Setting
Displays the Detector Events settings or On/Off states for Valve and External
Events.
Click
to view the Add/Event Run-Time Event dialog box. Run items
you select from this dialog are added to the time, item, and setting table.
Click
table.
to edit a selected run item listed in the Time, Item, and Setting
Select an item listed in the time, item, and setting table. Click
remove the selected run item from the run table.
to
Initial Values Group Box
External Event
Located on the back of your TRACE GC Ultra is a port with eight contacts
that switches external devices On/Off. During a specific run times you can
use these controls to set the status of these external switches prior to the run.
Factory defaults for the beginning of each run is off (not checked).
Setting Up Parameters for Run Table
1. Select a control from the Event Time Group Box. When do you want to
start the run at Prep Run or at Run Time?
2. Select a Detector Event, Valve Event, or External Event.
3. Select the controls available under the evnt type you selected
4. Click Ok.
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Using the Add/Event Run-Time Event Dialog
If you selected Add or Edit from the Run Table Page this dialog box displays.
Figure 3-20. Add/Run-Time Event Page View
Event Time group box
Select one of the following two options
Prep Run
This option makes the selected (Detector, Valve, or External) happen before
the run begins.
Run Time
This option makes the selected (Detector, Valve, or External) happen at the
time specified during the run.
Detector Event Group Box
Click the detector event button to activate a selected detector group of events:
Detector
3-96
Only the detectors you have selected from your TRACE GC Ultra Instrument
Configuration program display in the Instrument Setup window. Select the
one you wish to add a run time event for during this run. Each detector has
some programmable events, and the ones you have available depend on your
detector selection.
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Autozero
Range
Gain
Select this option to cause the detector offset to automatically adjust and
force the output signal to zero (1000 signal counts).
Select this option to change the electrometer sensitivity for ionization
detectors. This function is useful for known sample matrices, which exhibit
wide and varying analyte concentrations.
Select this option to change the TCD detector sensitivity. This is useful for
known sample matrices, which exhibit wide and varying analyte
concentrations.
Neg. Polarity
Select this option to invert the TCD detector response. This is useful for
quantifying a negative going peak such as Hydrogen when a carrier such as
Helium is used as carrier and reference gas.
Source current
Select this option to allow for source current changes for the NPD detector
during runtime.
Lamp
PID specific. Turns the UV lamp power on, which strikes the lamp and thus
creates a lamp current. This event is useful to enable the PID lamp only
during specific analysis times, such as after solvent elution.
Lamp current
PID specific. Selects the PID lamp current. Valid selections are low and high.
The higher the lamp current the more intense the transmitted lamp
transmission, which enhances sensitivity, but reduces lamp life.
Valve Event Group Box
If you have either a valve oven or sample valves then click the valve event
button to activate valve events:
Valve number-
Select from 1 to 8 for each external event to turn on from the Run Table page.
If you use all 8 then none are available for other events.
Valve type-
Select one: Switching, sampling, or Multiposition. Switching is On or Off.
Sampling is a valve used to inject a sample volume into the carrier stream.
Multiposition allows you to use 1 to however many positions your valve has.
Setting
Select Load or Inject for the sample valve settings. Whichever valve type you
select determines the available setting selections in this box.
External Event Group Box
External events are external valves, switches, and options.Click the external
event button to activate external events:
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External number
Setting
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Select which of the eight (8) external events you wish to program. There are
8 available open collector outputs on the GC rear panel, which can be
configured to switch external valves, switches, and other options.
Select On or Off to set the external event at the specified programmed run
time.
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Chapter 4
How To....
This Chapter contains these topics:
Installing the Desolvation Column and Connecting the Tee
100
Characterizing Columns
101
Post Column Splitting of the GCQ with the Flame Ionization Detector
102
Operating an FID with Xcalibur Software
107
Simultaneous Analysis on the Ion Trap and the FID
113
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4.1 Installing the Desolvation Column and Connecting
the Tee
1. Turn the carrier gas off at the keypad on the GC. Open the butterfly valve
to the OC injector, and manually insert an extra 250 uL into the inlet. The
syringe needle will extend into the GC oven. Install the desolvation
column by sliding it over the needle, using the needle as a guide. Tighten
the male nut with the tapered end of the ferrule pointing up while
pressing the column upward as far as it will go. Tighten the nut with a
wrench ¼ turn beyond finger-tight. Be sure to install the uncoated or
front end of the column into the injector.
2. Use the GCQ software to open a new method in the method editor and
save it to a new name. This is your LVI method. Press the GC icon and
then select Inlet and change the inlet selection to left. Save the method
and then send it to the GC. This will switch the DFPC or carrier gas
control to divert the carrier gas from the right inlet to the left. Turn the
carrier gas on at the keypad on the GC.
3. Place the effluent end of the desolvation column into a vial of solvent
and note bubbles indicating flow.
4. Position the end of the desolvation column with a ferrule and nut loosely
into the tee. If the tee has not been installed, remove it from the bag and
insert it into the solvent vent valve bulkhead from inside of the oven with
a ferrule and 1/16 nut. Slide the analytical column into the tee and inside
the desolvation column with the ferrule and nut in place. The analytical
column should protrude through the desolvation column about 4 cm.
Tighten the fittings ¼ turn beyond finger tight. Note flow through the end
of the analytical column by placing the end in a vial of solvent.
5. Install the column into the mass spectrometer as described in the GCQ
Plus Hardware Manual. If the analytical column was previously installed
in the right inlet, simply move it to the tee. You do not have to shut down
the mass spec, since the restriction of the narrow bore capillary will
prevent venting the detector to atmosphere.
6. Proceed to Characterizing Columns.
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4.2 Characterizing Columns
Columns must be characterized after they are installed in order to deliver the
correct flow rate set in the GC Method Editor. The procedure is performed at
the keyboard of the GC. A constant for the algorithm for regulation of
column flow is determined. This constant, K, is the restriction of the column.
Column characterization may be invoked at the keyboard of the GC. Press
the column characterization button. The display will show the electronic gas
control change the pressure and record the actual flow rate for each setting.
These values will be inserted into a formula to calculate the K value or
restriction of the column.
To test the column for leaks, raise the oven 50°C higher than the temperature
that the column characterization was performed and press the LEAK
CHECK button on the GC.
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4.3 Post Column Splitting of the GCQ with the Flame
Ionization Detector
Introduction:
Through Xcalibur a simultaneous analysis may be made on a GC detector
and the Mass Spec from of a single injection. A post column or effluent
splitter may be installed to “split the analytical column flow between the
Mass Spec and the Flame Ionization Detector (FID). An SGE outlet splitter
union with fused silica transfer lines, at a combined i.d. of 70-80% if the i.d.
of the analytical column, is used to make the split. The kit includes a single
hole ferrule for the analytical column side of the union and a two hole ferrule
for the split side for attachment of the two transfer lines to the Mass Spec and
the GC detector. The actual split is initially calculated to balance the flows
between the two outlets, with one operating under vacuum (Mass Spec) and
the GC Detector, at atmospheric pressure. The response may be enhanced
on the Mass Spec by shortening the transfer line, diverting more of the split
to it than the GC detector. Since the sample is being split between two
outputs, the injection volume must be doubled.
Installing the System to Meet Instrument
Specifications:
The GCQ should be installed to manufacturing specs with the standard test
column connected to the splitless injector and the Mass Spec. After specs
have been met, the Mass Spec is shut down and the splitter installed. Two
microliters of the 3 component GCQ test mix is injected at a concentration of
1 ng/uL in hexane. The response, retention time, and peak shapes are
checked. The retention times on the Mass Spec and the FID should be within
0.02 minutes of each other and the peaks should not show any significant
tailing. The response for the ion trap will be quite a bit higher than on the
Flame Ionization Detector (FID).
Connecting a Post Column SGE Splitter:
Using an SGE Capillary Outlet Splitter, two pieces of 0.1 mm i.d. fused silica
transfer line were cut: 60 cm in length for the Mass Spec and 20 cm in length
for the FID. Connect the analytical column to the inlet side of the splitter
union and connect the transfer lines to the outlet side with a SGE two hole
ferrule. Connect the outlet end of the transfer line to the FID with the
standard detector nut and the CE Instruments graphite ferrule Part #
29013489.
Materials Required:
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•
SGE phone # (800) 945-6154
•
SGE Outlet Splitter # 123630
•
Fused Silica 0.1mm x 10 meter # 062469
•
Two hole ferrules 0.3mm i.d. #072660
•
Single hole ferrule 0.4 mm i.d # 072663
Calculating Transfer Line Dimensions for the Mass
Spec and the GC Detector:
The flow calculator in Xcalibur was used to determine the length and i.d. of
the transfer lines for the split. The flow calculator is accessed by selecting the
TRACE GC Ultra icon button under the Instrument Setup. Press the word
Trace, and Flow Calculator will be listed in the menu. After selecting the
Flow Calculator, a dialog box will be displayed. Select helium for the carrier
gas type. First determine the pressure above atmospheric pressure (14.69
psi) required providing a flow rate of 1.5 ml/min, using the dimensions of the
test column at 50°C. The outlet is set to 1 Atm and the inside diameter to
0.25 mm with the length at 30 meters. The inlet pressure slide bar is
increased to achieve a flow rate of 1.5 ml/min. This value is 16.37 psi or
about 2-3 psi above atmospheric pressure.
Now you can determine the length of the transfer line for the FID. Set the
column outlet for the splitter to 1 Atm and the inlet pressure to 3 psi. The
oven temperature remains at 50°C. The i.d. was set to 0.1 mm. Reduce the
splitter length to a value such that a flow rate of ½ of 1.5 ml/min is shown or
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0.747 ml/min. The length should be 0.2 meters or 20 cm. The dimensions
for the FID splitter transfer line are 0.1 mm x 20 cm. Now calculate the
length for the transfer line to the Mass Spec.
Leaving the oven temperature at 50°C and the i.d. at 0.1 mm set the outlet of
the splitter to vacuum. With 3 psi at the inlet, increase the length until a flow
of 0.8 ml/min is shown. The dimensions for the Mass Spec splitter transfer
line should be 0.1 mm x 0.6 meters (60cm). At these conditions the flow
should be split evenly between the Mass Spec and the FID.
Installing the Post Column Splitter:
Insert the effluent end of the analytical column into the union with a ferrule
and insert the two transfer line sections into the other end of the union with
the two-hole ferrule. Note that there is flow of carrier out each transfer line
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section by placing them in a vial of solvent. A steady stream of bubbles will
be seen. The FID transfer line will be inserted into the FID beyond the jet
and then pulled back 2-3 mm below the jet to prevent burning the end of the
fused silica in the hydrogen flame, which would result in loss of response.
The loss would be severe; only a small peak for the solvent would be
observed. The make up flow for the FID is set to 30 ml/min of nitrogen or
helium, with the air at 350 ml/min and hydrogen to 30 ml/min. The detector
temperature is set to 250°C. The transfer line to the Mass Spec is inserted
2mm beyond the vespel tip of the heated transfer line into the trap. The Mass
Spec will indicate a vacuum of 20 mTorr at the lower flow rate of 0.8 ml/min.
Setting up the Carrier Flow:
The carrier gas flow exiting the analytical column was set to 1.5 ml/min
helium in the constant flow mode. The flow may be entered at the keypad on
the GC during set up and then in Xcalibur in the method under Instrument
Setup. With the restrictor attached to the Mass Spec, the carrier gas control is
set to vacuum compensation “off.
Leak Checking:
It is critical to tighten the splitter union so that no leaks are observed by
checking with a gas leak detector. It is not recommended to use any soap
leak test solutions like SNOOP on any fittings on the GCQ. Also check the
bulkhead fittings on the back of the GC for leaks.
Evaluating the DFPC Modules for the Detector and
Carrier Gases:
The DPFC module for the carrier gas should give a K value of about 1.879
with the outlet splitter installed to the FID and the Mass Spec when the
standard test column is installed ( Rtx 5 0.25 mm x 30 meter, 0.25 micron
film). Close the split and septum purge vent valves on the keypad of the GC
and test by pressing the column evaluation button and selecting the right
inlet. If the value is lower, then you have a leak. If the value is higher like 14
or 22, you have a defective DPFC module.
The FID has a gas flow test for validation of the gas module calibration. The
FID module is a type AC. This module provides control for the hydrogen, air
and make up flows. A special adapter is enclosed to attach to the top of the
FID for measuring the flows for this test. Turn the heater off to the FID and
allow it to cool. Remove the chimney to the detector and install the adapter.
Using an electronic flow meter verify the following flows:
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Test
Hydrogen
Air
Make up
Low Flow Test
20 +/- 2
60 +/-6
10 +/-1.5
High Flow Test
100 +/-5
300 +/-15
50 +/-3
If the flows are not within the specifications, order a new module.
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4.4 Operating an FID with Xcalibur Software
Introduction:
Xcalibur software allows the user to acquire from the Mass Spec and the
Flame Ionization Detector (FID) simultaneously or independently.
Configuring Xcalibur and the TRACE GC Ultra:
First configure Xcalibur for all hardware that is installed on the TRACE GC
Ultra. In order to acquire from the FID, a Channel will have to be selected
for acquisition of the analog signal in the TRACE GC Ultra Configuration
under the Detectors and Data Tab.
Verify that the FID is configured on the keypad of the TRACE GC Ultra.
Unplug the Handshake (HS) cable from the back of the TRACE GC Ultra
that connects to the Mass Spec. Review the menu for the Right Detector and
be sure that the gases are all configured correctly. Standing in front of the
GC, the right detector position is on your right side.
Connecting the Gases:
Connect hydrogen, air, and a make up of helium or nitrogen to the bulkhead
fittings on the back of the GC. Set the pressure on the regulators at each tank
to about 50 psi. The DPFC must be checked by placing a plug in the column
end of the detector and installing the brass flow adapter for measuring flows
on the detector base of the FID. You must remove the outside chimney to the
detector first by unscrewing the thumbscrew and lifting the entire detector
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body off. Verify the following flows and tolerances:
• H2
20 ml/min +/-2
60 ml/min +/- 5
• Air
60 ml/min +/-6
300 +/-15
• Makeup
10 +/-1.5
50 +/-3
If the flows do not match the tolerances, then change the DPFC module.
Remove the flow adapter and reinstall the detector body.
Installing the Test Column:
The test column is installed into the split/splitless injector. The column is
inserted beyond the FID jet and then pulled back 2-3 mm. This prevents
burning the end of the column in the flame. If the column is burned at the tip,
the response will be low and only a small peak for the solvent will be seen.
Column Characterization:
Once the column has been connected, set the base temperature to 250°C and
perform the column characterization. The Right carrier is set to constant
pressure at 30 kpa with vacuum compensation off. Check to see that the
split/splitless septum purge and split vents are off, by pressing VALVE on the
keypad and ENTER. Next perform the column characterization. A “K value
of 0.148 is typical for the Rtx 5 0.32mm x 7 meter, 0.25 micron film GC test
column.
Igniting the Flame:
Once the column has been characterized, the detector gases may be turned on
at the key pad of the GC and the flame ignited. Press ON at the first display
for the Right Detector. The flame will ignite and the signal value displayed
will go up. You will hear a soft pop. A shiny wrench may be held next to
one of the exhaust holes at the top of the detector body and a condensation of
water will be seen from the flame.
Setting up the Method:
In Xcalibur, under Instrument Setup, enter the values shown below for the
method:
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The Mass Spec will not be run, but you should set the temperatures to
appropriate values for the ion source and the transfer line. Also put in a 5
minute filament delay, as a precautionary measure.
The oven program is set to 50°C, 1.0 min; 20°C/min; 200°C, 1.0 min. The
split/splitless injector is set with a split flow of 60 ml/min in the splitless
mode with a 1 minute inject time at 230°C.
Setting up a Sequence in Xcalibur for Acquisition of
the FID Only:
Write a sequence for injection of the test mix. When activating the sequence
to run open the dialog box, “Change Instruments. Remove the Mass Spec
from the list by a right mouse click on the word YES by Mass Spec. Press
OK.
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Now you are set up to run only the FID.
The real time plot will appear on the home page for the FID
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S
e
Setting Up Qual Browser for the FID Analog
Chromatogram:
Open the file. If this were a dual Mass Spec and FID run, you would have to
select Channel 1 and set the Detector type to analog.
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Meeting FID Specifications:
One uL of the test solution is injected at 20 ug/ml in hexane of C12H26,
C14H30, and C16H34. A real time plot will be visible under the home page
without the Mass Spec TIC. A representative chromatogram is shown below
in Qual Browser.
1 uL of the FID test solution is injected in the split/splitless inlet with an
injection time of 1.0 minute. The FID gas flows were set to: hydrogen at 30
ml/min, air at 350 ml/min, and makeup at 30 ml/min nitrogen. The FID
detector base temperature was set to 250°C and the inlet to 230°C. The range
was put on 1. The spec calls for area counts
> 3,500,000 for each
component. The ratio of C12H16/C16H34 must be 1.0 +/- 0.1. If the
column was installed correctly and the injection time is set to 1.0 minute or
less, a sharp front and back for the solvent peak should be seen. The peak
shapes should be symmetrical.
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4.5 Simultaneous Analysis on the Ion Trap and the FID
Configuration:
Close Xcalibur and open the Configuration icon. Select the TRACE GC
Ultra and then configure. The configuration may be uploaded directly from
the GC or entered. Go to the Detector and Data Tab and select Channel 1 for
the Right FID with a scan rate of 10 Hz. Select Done and close
Configuration. Open Xcalibur and proceed to Instrument Set up. By
specifying a Channel for the detector, you invoke acquisition in every run.
When you select “NONE for the Detector channel, no acquisition of a GC
detector will occur. Press OK to save the changes. Then open Xcalibur.
Instrument Method Set Up:
Go to Instrument Set Up from the Home Page and select new method. Enter
the FID parameters listed below:
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By entering a temperature for the FID, the detector will be turned on during
acquisition and appear as an analog plot in real time at the bottom of the page
with the real time spectrum at the top and TIC in the center.
Opening a Data File in Qual Browser:
To open a data file in Qual Browser, select the file. The TIC will appear.
Press the right mouse button and select ranges.
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A dialog box will appear, select another TIC and then change the detector
from Mass Spec to Analog.
Channel 1 will appear as selected type of file. Press OK.
The TIC and FID chromatogram will be displayed. Press the integration
button on the tool bar and integrate the peaks in the TIC and FID
chromatogram. Also set the display labels to area. Press the right mouse
button with the mouse over the chromatogram for the FID and select Peak
Detection settings to allow integration of the peaks. The default integration
is set for 10% of the highest peak. With a FID the solvent is the highest peak,
so the Peak Identification has to be set to 0.1%
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The spectrum may be viewed as usual by adding another cell and setting it to
view spectrum. Then select a peak in the TIC and view the spectrum.
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Developing a Processing Method:
Separate processing methods are created for the Mass Spec and the
GCdetector. The following order must be followed to open a GC
detectorchromatogram:
1. Open Processing Set Up and select new method file. Under Options
verify that the chromatography is by GC.
2. Set the Detector Type to Analog.
3. Open a raw data file and enter a name for the first analyte.
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Press OK. Be sure that the Detector Type is still Analog. The FID
chromatogram will appear.
4. Zoom in on the analyte peaks by pinning the cell with the
chromatogramand dragging the mouse across the area to be enlarged.
5. Enter the retention time for the first analyte and press OK. The peak of
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interest will be integrated. Continue building your method as instructed
in the on line Help.
6. Select the remaining analytes by retention time and press OK with their
appropriate name.
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Report Writing:
After establishing a report template in Merlin, the raw data files may be
reprocessed in a batch and reports printed out. A calibration curve may be
viewed in Quan Browser.
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Chapter 5
Glossary
analyte
carrier gas
Any chemical component to be analyzed. Internal standards, external
standards, target components, quality control samples, knowns, and
unknowns can all be considered analytes
The mobile phase in gas chromatography. The carrier gas carries the
analyte mixture through the GC column, where it is separated into its
individual components. The carrier gas flows through the GC column at a
specific rate, measured either as a linear velocity (cm/sec) or as a flow
rate (mL/min). Common carrier gases are helium, hydrogen, and nitrogen.
Hydrogen offers the best chromatographic properties (optimum resolution
at the highest flow rates). However, because hydrogen is flammable,
helium is often used as a safer alternative for a carrier gas.
See also: chromatography, constant flow, linear velocity, flow rate, and
resolution
chromatography
A process in which a chemical mixture carried by mobile phase (gas or
liquid) is separated into its individual components as a result of
differential distribution of the analytes as they flow around or over a
stationary phase (liquid or solid).
See also: liquid chromatography and gas chromatography.
column flow
The flow of mobile phase of carrier gas through the chromatographic
column. Column flow is usually reported as a linear velocity (cm/sec) or
as a flow rate (mL/min).
See also: linear velocity and flow rate.
constant flow
The type of flow control available on gas chromatographs to regulate the
flow of carrier gas through the GC column.
Flow rates are specified in units of mL/min.
In the Constant Flow mode, the flow rate of the carrier gas is maintained
at a designated setting for the duration of the GC run. The head pressure
of the carrier gas in the injector is electronically adjusted during the oven
temperature program to compensate for changes in the gas viscosity and
thereby maintain the desired flow rate.
data system
The computer hardware and software used to control the instrument and
to record, analyze, and interpret the data collected by the instrument.
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electronic pressure
control
A system on the Finnigan GC, CE 8000 TOP GC, and the HP 5890 that
controls the head pressure on a GC column at the injector. The pressure can
be maintained or modulated during an analysis to affect the separation
efficiency and speed of an analysis
final value
For the first step, this box sets the initial temperature for the program. For all
other steps, this final value is the value the ramp is intended to reach.
Temperatures can range from -80°C to the maximum oven temperature
value.
flow rate
The rate of flow of the carrier gas through the GC column. The unit of
measurement for flow rate is mL/min. Gas chromatography is defined by the
separation of analytes by partitioning between a mobile phase (the carrier
gas) and a stationary phase. This mobile phase flow rate must be regulated to
provide reproducible results.
See also: flow control
flow control
Method for controlling the flow of carrier gas through the GC column.
Several methods are available depending on the type of GC
gas chromatograph
An instrument that separates a sample mixture into its chemical components
by gas chromatography.A GC typically consists of an inlet for introduction
of the sample, a column for separation of the analytes , and a detection
system. The characteristic retention time of each component of the mixture
determines when each component enters the detector. On the GCQ, the GC
can be operated from the either the data system or the GC front panel. A
serial I/O connection (COM1 port) between the GC and the data system
allows the GC parameters to be set up and controlled directly by the data
system through the Analysis window and the Instrument Setup window.
gas chromatography
One of the most common instrumental analysis techniques in use. When
properly used, it provides both qualitative (what is it?) and quantitative (how
much?) information about individual components in a sample.
Gas chromatography involves separating the different components in a
sample mixture from each other.
The separation is produced by injecting the sample into a carrier gas stream
(usually through an injector) that passes through a GC column that is packed
with a solid packing or coated with a liquid stationary phase. The GC column
is housed within a temperature-programmable oven.
Varying the oven temperature during a GC run affects the resolution of
components as well as their retention time. Under reproducible temperature
and carrier gas flow conditions, the retention time of a component is
descriptive of it. The components in a mixture can then be identified by
comparing their retention times with those of known standard components.
With a mass spectrometric detector, the mass spectra of the components are
also descriptive of the components, offering another method of identification.
In gas chromatography, the components are primarily separated by
differences in volatility and structure. Some components and samples are not
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suitable for gas chromatographic analysis due to their physical and chemical
properties.
GC/MS
head pressure
Analysizing organic compounds by gas chromatography with a mass
spectometer. The mass spectrometer detects analyte concentration found and
the analytes identity by comparing the analytes to a library of known spectra.
The pressure of carrier gas in the injector of the GC. The head pressure
creates a specific flow of the carrier gas through the GC column.
See also: flow rate , and linear velocity.
hold time
The time in minutes to maintain the temperature specified in the Final Value
control box. Referred to as Holdup time in the Flow Calculator . This refers
to an unretained component’s (at column termperature T) elution time. This
is a measure of time that the sample components spend in the mobile phase.
Hold up time is measured to determie the average linear velocity.
initial
This is the initial temperature of the GC during injection and at the beginning
of the run.
injection mode
injector
Type of injection used to introduce a sample mixture onto the GC column.
Types of injection modes include Split , Splitless, Large Volume Injection,
and on-column injection
The inlet system for a gas chromatograph. The injector is a gas-tight
connection at the entrance of the GC column that delivers carrier gas to the
column and provides a path for introduction of the sample into the GC.
See also: Large Volume Injection, on column injector, split/splitless injector,
and temperature programmable injector.
ion polarity
The charge on an ion (positive or negative).
ion source
The part of a mass spectrometer where ions are formed (molecular ions and
fragment ions, or in an MS/MS experiment, precursor ions).
Large Volume Injection
Injection mode possible using a Finnigan TPI and the CE On-Column
Injector (OCI). In this mode, up to 500 microliters of sample can be injected
into the GC. With the Finnigan TPI, during the injection, the temperature of
the injector is held slightly above the boiling point of the solvent, but below
the boiling points of the analytes, with the split vent open. After most of the
solvent evaporates, the split vent is closed, and the temperature of the injector
is ramped quickly to a high enough temperature to cause the analytes to
vaporize and be swept onto the analytical column. LVI is accomplished with
the CE On-Column Injector by incorporation of a desolvation pre-column
connected through a tee union to the analytical column and the solvent vent
valve. During the injection, the oven temperature is held below the boiling
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point of the solvent during desolvation while the vent valve is open. A high
carrier gas flow rate sweeps the more volatile solvent out the vent valve
while the analytes remain coated on the pre-column. The vent valve is then
closed and the oven temperature programmed up to vaporize the analytes for
transfer into the analytical column.
See also: injection mode, temperature programmable injector and on column
injector.
linear velocity
The rate of movement of the carrier gas through the GC column measured in
cm/sec.
See also: flow rate and flow control.
liquid chromatography
A form of elution chromatography in which a sample partitions between a
stationary phase of large surface area and a liquid mobile phase that
percolates over the stationary phase. As components elute from the
chromatographic column they flow into a detector and generate a signal. The
characteristic time each component elutes from the liquid chromatograph and
enters the detector is called the component’s retention time
negative ion
An atom, radical, molecule, or molecular moiety that has gained one or more
electrons, acquiring an electrically negative charge. The charge state
becomes -1, -2, -3, etc., depending upon the number or electrons acquired.
See also: positive ion and ion polarity.
on-column injection
Sample injection directly inside the capillary column rather than in a liner
located in a flash vaporization off column mode.
See also: negative ion and ion polarity.
on column injector
The On-Column Injector (OCI) allows to inject a sample directly into a 0.25
or 0.32 mm capillary column or 0.53 mm wide-bore column. Primary and
secondary cooling system keep the injection block at ambient temperature
and the injection zone cool to prevent sample vaporizazion and ensure
complete sample transfer from the syringe to the column.
A special versions of this injector allows:
•
to introduce large volumes of liquid sample (LVOCI).
•
to operate at high oven temperature by using an option HOT device
(HOTOC).
See also: Large Volume Injection.
positive ion
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An atom, radical, molecule, or molecular moiety that has lost one or more
electrons or has been protonated, thus acquiring a positive charge. The
charge state becomes +1, +2, +3, etc., depending upon the number of
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electrons lost or protons gained.
See also: negative ion and ion polarity.
pressure program
Type of flow control used to regulate the flow of carrier gas through the GC
column. head pressureat the injector is specified in units of psi, and the
ramps are in units of psi/min. This produces a certain flow rate of the carrier
gas through the GC column. The head pressure is controlled by an EPC . The
pressure is programmed as a method development or optimization tool.
purge vent
On a Split/Splitless (SSL) Injector, the septum purge gas flows out this vent
into the atmosphere. The purge vent may have a purge valve on it, which
allows the purge flow to be regulated.
ramp
Use the ramps to increase the oven temperature at a specific rate in
°C/minutes to a final value in °C. Using multiple ramps allows for finer
control of the component separation. A graph is generated during GC
temperature method development to display the temperature versus time plot
that is being created or edited.
rate
This is the rate of change of the temperature when increasing the temperature
from one value to the next. This rate is described in degrees Celsius per
minute (°C/min). The ramp begins at the previous step’s final temperature
value and proceeds to the current step’s final temperature at the specified
rate.
resolution
A measure of the ability of a chromatographic column to separate
components during a chromatographic experiment. Chromatographic
resolution between two adjacent peaks is defined as the distance between the
centers of the peaks divided by their average peak width (measured at 10% of
the peak height). A resolution of 1.00 indicates baseline separation.
retention time
The total time that a component is in the chromatographic column. This is
measured from the time of injection until elution. If the maximum signal
from an analyte is detected 5 minutes and 14 seconds after injection, then
the analyte has a retention time (on the column) of 5:14
secondary cooling
Cools the On-Column Injector and the first few centimeters of the GC
column. This is an external gas supply (typically bottled air or CO2) that is
supplied to the secondary cololing valve located on the rear of the GC. Use
this option to cool the column head and the first few centimeters of column
where sample is introduced. Flow rate is depencdant upon the pressure
supplied from the gas source. Secondary cooloing gas consumption is usually
very large so you should minimze the time between the GC Ready mode and
Run Start mode.
split injection
One type of injection mode available on a split/splitless injector. As the
injection is made (and at all times during the GC run), the split vent is opened
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to allow a specific portion of the sample to be swept into the atmosphere (that
is, split away), while the rest of the sample is swept onto the GC column.
Only a certain percentage of the sample makes it onto the GC column
depending on the ratio of the split flow to the column flow (the split ratio).
Split injection is used for the analysis of high concentration samples that
would overload the GC column if all of the sample were placed onto the
column. Some types of samples can not be diluted with a solvent because of
the presence of volatile analytes that would co-elute with most commonly
used solvents, making split injection necessary.
splitless injection
One type of injection mode available on a Split/Splitless (SSL) Injector. In
this mode, the split vent is closed during the injection, and a large amount of
sample is transferred to the GC column from the injection port. This type of
injection is used for trace residue analysis.
See also: split/splitless injector and split vent.
split/splitless injector
A type of injector available on a gas chromatograph. This is the standard
injector offered on the GCQ. The SSL Injector is made up of a septum nut, a
septum, a liner, a metal body, an influent line for the carrier gas, a septum
purge vent, and a split vent that allows a portion of the carrier gas to be
vented into the atmosphere.
See also: split vent, purge vent, carrier gas, flow rate, split injection , and
splitless injection.
split vent
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The exit port of the Split/Splitless (SSL) Injector. The split vent is opened
and closed by the split valve and/or split solenoid. When the split vent is
open, a portion of the carrier gas and sample mixture (if present) is allowed
to pass through the split vent into the atmosphere.
subambient
temperature
Below room temperature or ambient temperature. The oven of the gas gas
chromatograph, Ttemperature programmable injector , and on column
injector can be cooled to subambient temperatures if the appropriate valving
and coolant supply is configured accordingly.
surge pressure
An option available on the with the split/splitless injector. If the Use Surge
Pressure check box is selected in the GC Instrument Setup window Pressure
tab, you can enter the pressure to surge to (in psi), the time (minutes into the
GC run) for the surge to come on and the time for the surge to go off.
During the GC run, the head pressure will be set to the value specified in the
Pressure box and the On Time, and it will hold at that pressure until the Off
Time. The selected head pressure will override the EPC value(s) while it is
on. surge pressure is often coordinated to be on during the injection of a
sample into the injection port. By surging the pressure during the injection,
then the sample is pushed more quickly onto the GC column in a tighter
band. This helps improve loading of the components. The surge pressure it
also useful with analytes that are thermally degradable and tend to break
down when exposed to the high temperatures of the injector. Using surge
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pressure helps to sweep the sample out of the injection port and onto the GC
column quickly.
See also: electronic pressure control.
temperature program
A temperature program where the oven temperature is changed at a specified
rate.
temperature
programmable injector
The TPI is an injector available as an option for the Finnigan GC. This
injector provides the capability for temperature programming of the injector.
The injector is a universal injector for capillary gas chromatography. The
injector may be operated in the cool on-column mode, large volume mode,
isothermal split or splitless mode, or temperature programmed mode.
See also: on-column injection, Large Volume Injection, split injection, and
splitless injection.
total time
This is the GC run time. It is calculated by summing the ramp times and hold
times in the temperature program. The total elapsed time for a run cannot
exceed 650 minutes. At 650 minutes the run terminates and the oven
temperature returns to the initial oven temperature. In an isothermal
operation (no ramp steps, or RATE=0), the instrument internally sets the run
time to a maximum of 650 minutes.
UltraFast Module
The Ultra Fast Module (UFM) is a GC device allows the direct heating of the
analytical capillary column properly installed inside the GC oven. The UFM
device integrates a GC capillary column with the components for its
temperature control.Compared to conventional air circulating oven, this
device features faster temperature programming.
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