HP 6890 GC Operating Manual Vol. 2 Inlets (G1530

HP 6890 GC Operating Manual Vol. 2 Inlets (G1530
Operating Manual
Volume 2. Inlets
HP 6890 Series
Gas Chromatograph
.Hewlett-Packard
Company 1989—1996
All Rights Reserved.
Reproduction, adaptation,
or translation without
permission is prohibited,
except as allowed under
the copyright laws.
HP part number
G1530-90450
First Edition, Oct 1996
Replaces parts of
G153090310 Operating
Manual and parts of
G153090320 Maintenance
and Troubleshooting
Manual
Printed in USA
Warranty
The information contained
in this document is subject
to change without notice.
Hewlett-Packard makes no
warranty of any kind with
regard to this material,
including, but not limited
to, the implied warranties
of merchantability and
fitness for a particular
purpose. Hewlett-Packard
shall not be liable for errors
contained herein or for
incidental or consequential
damages in connection with
the furnishing,
performance, or use of this
material.
Safety Information
The HP 6890 Gas
Chromatograph meets the
following IEC
(International
Electrotechnical
Commission) classifications:
Safety Class 1, Transient
Overvoltage Category II,
and Pollution Degree 2.
This unit has been
designed and tested in
accordance with recognized
safety standards and
designed for use indoors. If
the instrument is used in a
manner not specified by the
manufacturer, the
protection provided by the
instrument may be
impaired. Whenever the
safety protection of the HP
6890 has been
compromised, disconnect
the unit from all power
sources and secure the unit
against unintended
operation.
Refer servicing to qualified
service personnel.
Substituting parts or
performing any
unauthorized modification
to the instrument may
result in a safety hazard.
Disconnect the AC power
cord before removing
covers. The customer
should not attempt to
replace the battery or fuses
in this instrument. The
battery contained in this
instrument is recyclable.
Safety Symbols
Warnings in the manual or
on the instrument must be
observed during all phases
of operation, service, and
repair of this instrument.
Failure to comply with
these precautions violates
safety standards of design
and the intended use of the
instrument.
Hewlett-Packard Company
assumes no liability for the
customer’s failure to
comply with these
requirements.
WARNING
A warning calls attention
to a condition or possible
situation that could cause
injury to the user.
CAUTION
A caution calls attention to
a condition or possible
situation that could
damage or destroy the
product or the user’s work.
Caution. Refer to
accompanying
documents.
Indicates a hot
surface.
Indicates hazardous
voltages.
Indicates earth
(ground) terminal.
Indicates radioactivity hazard.
Indicates explosion
hazard.
Little Falls Operation
Hewlett-Packard Company
2850 Centerville Road
Wilmington, DE 19808-1610
Important User
Information for In Vitro
Diagnostic Applications
This is a multipurpose
product that may be used
for qualitative or
quantitative analyses in
many applications. If used
in conjunction with proven
procedures (methodology)
by qualified operator, one
of these applications may
be In Vitro Diagnostic
Procedures.
Generalized instrument
performance characteristics
and instructions are
included in this manual.
Specific In Vitro Diagnostic
procedures and
methodology remain the
choice and the
responsibility of the user,
and are not included.
Sound Emission
Certification for Federal
Republic of Germany
Sound pressure Lp
< 65 dB(A)
During normal operation
At the operator position
According to ISO 7779
(Type Test)
When operating the HP
6890 with cryo valve
option, the sound pressure
74.6 dB(A) during cryo
valve operation for short
burst pulses.
Schallemission
Schalldruckpegel LP
< 65 dB(A)
Am Arbeitsplatz
Normaler Betrieb
Nach DIN 45635 T. 19
(Typprüfung)
Bei Betrieb des HP 6890
mit Cryo Ventil Option
treten beim Oeffnen des
Ventils impulsfoermig
Schalldrucke Lp bis ca.
74.6 dB(A) auf.
Contents
Chapter 1. Introduction to Inlets
Inlet types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Select pressure units—psi, bar, kPa . . . . . . . . . . . . . . . . . . . . . . . . . . .
The inlet and column control tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The column control tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The column control table—defined capillary columns . . . . . . . . . . . . . . . . . .
The column control table—packed or undefined capillary columns . . . . . .
What is gas saver? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using gas saver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pre Run and Prep Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The [Prep Run] key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Auto Prep Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Septum purge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2
5
6
7
7
9
11
12
13
13
14
15
Chapter 2. The Split/Splitless Inlet
Part 1. Using a Split/Splitless Inlet
Standard and high-pressure versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Septum tightening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Changing the liner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Split mode pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The control table—split operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using the split mode with the column defined . . . . . . . . . . . . . . . .
Procedure: Using the split mode with the column not defined . . . . . . . . . . . . .
Splitless mode pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The control table—splitless operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using splitless mode with the column defined . . . . . . . . . . . . . . . .
Procedure: Using splitless mode with the column not defined . . . . . . . . . . . . .
Pulsed split and splitless modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The control table—pulsed split mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using the pulsed split mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The control table—pulsed splitless operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using the pulsed splitless mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18
18
19
19
21
22
23
24
25
26
27
28
29
30
31
32
33
34
Part 2. Maintaining a Split/Splitless Inlet
Changing septa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Changing the septum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the O-ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Changing the O-ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing the inlet base seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Replacing the inlet base seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing the gas plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing an EPC split/splitless inlet . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing a nonEPC split/splitless inlet . . . . . . . . . . . . . . . . . . .
Procedure: Correcting leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Cleaning the inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
37
39
41
43
44
46
47
51
53
54
Chapter 3. The Purged Packed Inlet
Part 1. Using a Purged Packed Inlet
Liners and inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Installing liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Installing glass inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The control table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Packed columns or column not defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Defined capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using packed and undefined capillary columns . . . . . . . . . . . . . . .
Procedure: Using defined capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . .
59
61
63
65
65
65
66
66
Part 2. Maintaining a Purged Packed Inlet
Procedure: Changing septa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Changing the O-ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing the gas plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing an EPC purged packed inlet . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing a nonEPC purged packed inlet . . . . . . . . . . . . . . . . .
Procedure: Correcting leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Cleaning the inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
68
72
74
75
78
80
81
Chapter 4. The Cool On-Column Inlet
Part 1. Using a Cool On-Column Inlet
Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic or manual injection with septum nut . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual injection with a cooling tower and duckbill septum . . . . . . . . . . . . . . .
Procedure: Changing the septum nut or cooling tower and septum . . . . . . . . . . .
Procedure: Installing an insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Check the needle-to-column size . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Manual injection with septum nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Manual injection with cooling tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Retention gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inlet temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CryoBlast (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Track oven mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature programming mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cryogenic considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setpoint ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Programming the temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Operating the cool on-column inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
85
87
88
89
90
91
92
93
94
94
94
94
95
95
95
96
97
Part 2. Maintaining a Cool On-Column Inlet
Cool on-column inlet hardware problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The inlet cools very slowly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The inlet is unable to reach a temperature setpoint . . . . . . . . . . . . . . . . . . .
The syringe needle bends during injections . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Replacing the fused silica syringe needle . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Installing a fused silica needle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing septa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Changing septa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Cleaning the inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing the gas plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Leak testing a cool on-column inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Correcting leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
100
100
100
100
101
102
103
104
106
109
110
113
Chapter 5. The Programmable Temperature Vaporization Inlet
Part 1. Introducing the HP PTV
Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sampling heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Heating the inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Additional temperature ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling the inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuring the PTV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutdown behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
116
116
117
118
119
119
120
120
122
Part 2. Using the Split Modes
Flow pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cold split introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hot split introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control table parameters—split mode operation . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using split mode with the column defined . . . . . . . . . . . . . . . . . . .
Procedure: Using split mode with the column not defined . . . . . . . . . . . . . . . .
Pulsed modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control table parameters—pulsed split mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using pulsed split mode with the column defined . . . . . . . . . . . . .
Procedure: Using pulsed split mode with the column not defined . . . . . . . . . .
123
124
124
124
125
126
127
128
129
130
131
Part 3. Using the Splitless Modes
Flow patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cold splitless introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hot splitless introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control table parameters—splitless operation . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using splitless mode with the column defined . . . . . . . . . . . . . . . .
Procedure: Using splitless mode with the column not defined . . . . . . . . . . . . .
Pulsed splitless mode operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control table parameters—pulsed splitless operation . . . . . . . . . . . . . . . . . .
Procedure: Using pulsed splitless mode with the column defined . . . . . . . . . .
Procedure: Using pulsed splitless mode with the column not defined . . . . . .
132
135
135
135
136
137
138
139
140
140
141
142
Part 4. Using the Solvent Vent Mode
Flow patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature, pressure, and flow considerations . . . . . . . . . . . . . . . . . . . . . . . . . .
Sequence of operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When is Start Run? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control table parameters—solvent vent operation . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Using solvent vent mode with the column defined . . . . . . . . . . . .
Procedure: Using solvent vent mode with the column not defined . . . . . . . . .
Large volume injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas chromatograph requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Automatic sampler requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ChemStation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control parameters—Injector configuration subscreen . . . . . . . . . . . . . . . .
Control parameters—Injector screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calculated values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
143
145
146
147
148
149
151
152
153
153
153
154
154
155
155
Part 5. Maintaining a PTV
Inlet adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Replacing inlet adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Installing columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The septumless head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Removing the septumless head . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Cleaning the septumless head . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Replacing the Teflon ferrule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The septum head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Removing the septum head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Changing the septum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Glass inlet liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Replacing liners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Consumables and replaceable parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
161
161
162
164
164
165
167
168
169
170
171
172
174
Chapter 6. The Volatiles Interface
Part 1. Using a Volatiles Interface
Split mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Understanding the pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the control table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Operating in the split mode with the column defined . . . . . . . . . .
Procedure: Operating in the split mode with the column not defined . . . . . . .
Splitless mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Understanding the pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the control table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Operating in the splitless mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Direct mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Understanding the pneumatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing your interface for direct sample introduction . . . . . . . . . . . . . . .
Procedure: Disconnecting the split vent line . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Configuring for a direct injection . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the control table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Operating in direct mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
180
180
182
184
185
186
187
187
189
192
193
194
194
196
196
198
199
201
202
Part 2. Maintaining a Volatiles Interface
Procedure:
Procedure:
Procedure:
Procedure:
Procedure:
Procedure:
Installing columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing or cleaning the interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak testing the gas plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Leak testing the system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing the interface for a leak test . . . . . . . . . . . . . . . . . . . . . . . . . .
Correcting leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
204
208
211
212
215
216
Part 3. Connecting to an External Gas Sampler
Procedure: Connecting the HP 7694 headspace sampler . . . . . . . . . . . . . . . . . . . . 218
Procedure: Connecting the HP 7695 purge and trap concentrator . . . . . . . . . . . . 221
Chapter 7. NonEPC Inlets
Purged packed inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Split/splitless inlet—split mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Split/splitless inlet—splitless mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Configuring a nonEPC inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inlet control tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Column control tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Setting carrier flow for the purged packed inlet . . . . . . . . . . . . . . . . . . .
Procedure: Setting flows for the split mode inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Procedure: Setting flows for the splitless mode . . . . . . . . . . . . . . . . . . . . . . . . . . . .
226
226
226
227
227
228
229
230
231
233
Appendix A: Configuration Information
Preparing for analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
To configure the carrier gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
To select a column mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
To set the initial flow or pressure or average linear velocity . . . . . . . . . . . . . . .
To enter a pressure or flow program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
236
237
238
239
240
1
Inlet types, 2
Using hydrogen, 2
Procedure: Select pressure units—psi, bar, kPa, 5
The inlet and column control tables, 6
The column control tables, 7
Defined capillary columns, 7
Packed or undefined capillary columns, 9
What is gas saver?, 11
Procedure: Using gas saver, 12
Pre Run and Prep Run, 13
The [Prep Run] key, 13
Procedure: Auto Prep Run, 14
Septum purge, 15
Introduction
to Inlets
Chapter 1.
Introduction to Inlets
Inlet types
The HP 6890 GC has five types of inlets available. All are offered with
electronic pneumatics control (EPC) and two are offered without.
Table 1.
Inlet Types
Inlet Type
Gas Control
Split/splitless
EPC and nonEPC
Purged packed
EPC and nonEPC
Cool on-column
EPC only
Programmed temperature vaporization
EPC only
Volatiles interface
EPC only
Using hydrogen
WARNING
When using hydrogen (H2), as the carrier gas, be aware that hydrogen
(H2) gas can flow into the oven and create an explosion hazard.
Therefore, be sure that the supply is off until all connections are made,
and ensure that the inlet and detector column fittings are either
connected to a column or capped at all times when hydrogen (H2) gas is
supplied to the instrument.
Hydrogen (H2) is flammable. Leaks, when confined in an enclosed space,
may create a fire or explosion hazard. In any application using hydrogen
(H2), leak test all connections, lines, and valves before operating the
instrument. Always turn off the hydrogen (H2) supply at its source before
working on the instrument.
2
Inlets
Table 2.
An Overview of Inlets
Inlet Type
Split/splitless
Column
type
Mode
Sample type
Capillary
Split
High concentration
Pulsed split
High concentration
Splitless
Low concentration
Pulsed splitless
Low concentration Useful with large (>2 ³L)
injections
n/a
Low concentration Minimal sample discrimination
or thermally labile and decomposition
Cool
on-column
Capillary
Purged
packed
Packed;
1/8- and
1/4-in. metal, 1/8-in.
glass
n/a
Any
Large bore
capillary
n/a
Any
Capillary
Split
High concentration
Programmed
Temperature
vaporization
Volatiles interface
Pulsed split
Comments
New technique; may be useful
with large (>2 ³L) injections
Capillary
Low concentration
Pulsed splitless
Low concentration
Very little,
most is
vented
All
Satisfactory if resolution is not
an issue
Very little,
most is
vented
High concentration
Splitless
Sample
to Column
All
Solvent vent
Low concentration For large (>x ³L) injections;
multiple injections concentrate
analytes while venting solvent
Direct
Low concentration Lowest possible dead volume
All
Split
High concentration
Very little
Splitless
Low concentration
Max total flow = 100 mL/min
All
3
Inlets
Table 3.
Column Size and Carrier Gas Flow Rate
Column
Type
Column Size
Carrier Gas Flow Rate
Hydrogen
Packed
Capillary
Helium
1/8 in.
30
1/4 in.
60
50 ³ id
0.5
0.4
100 ³ id
1.0
0.8
200 ³ id
2.0
1.6
250 ³ id
2.5
2.0
320 ³ id
3.2
2.6
530 ³ id
5.3
4.2
These flow rates, in mL/min at normal temperature and pressure Û& and 1 atm) are recommended for all column temperatures.
For capillary columns, flow rates are proportional to column
diameter and are 20% lower for helium than for hydrogen.
4
Inlets
Procedure: Select pressure units—psi, bar, kPa
You can display pressure in psi, bar, or kPa. To check the units you are
using, pressing the [Info] key while the cursor is on the Pressure line of a
control table. To change the display units:
1. Press [Options].
2. Scroll to Keyboard & Display and press [Enter].
OPTIONS
Calibration
Communication
Keyboard & Display
Diagnostics
<
3. Scroll to Pressure units: and press [Mode/Type].
Keyboard lock
Off
Key click
On
Warning beep
On
Method mod beep
Off
KEYBOARD OPTIONS
Pressure units:psi
<
Radix type:
.
PRESSURE UNITS
*psi
bar
kPa
<
4. Choose a new pressure unit and press
[Enter].
Table 4.
Pressure Unit Conversions
To Convert
to
Multiply by
psi
bar
0.0689476
kPa
6.89476
psi
14.5038
kPa
100
psi
0.145038
bar
0.01
bar
kPa
5
Inlets
The inlet and column control tables
The tables for the inlet and column are interrelated. If you set a pressure
at the column control table, that same pressure setting is active on the
inlet control table, and vice versa. Although pneumatics can be
controlled from either the column or the inlet, the column should be
considered first.
COLUMN 1 (He)
Dim
30.0 m 320 u
Pressure
10.0
10.0
Flow
0.7
Velocity
19
Mode: Constant flow
FRONT INLET (S/SL)
Mode: Splitless
Temp
250
250 <
Pressure
10.0
10.0
Purge time
0.75
Purge flow
15
Total flow
??
Gas saver
Off
The pressure readings—both setpoint and actual—are identical on the
column and inlet control tables.
6
Inlets
The column control tables
The control tables change depending on your column configuration. The
next few pages describe the column control tables for the two types of
columns, capillary and packed.
The column control table—defined capillary columns
If your column is defined, your control table will be similar to Figure 1.
The title This heading identifies the column—Column 1 or Column 2—
and the type of carrier gas configured to the inlet (in parentheses).
Dim This line shows the column dimensions you have specified. Column
length is in meters (m) and column inside diameter is in microns (³).
Pressure, flow, and velocity are related. If the column is defined, enter
any one of them and the GC computes and displays the other two.
Pressure The setpoint appears at the far right. The number at the left
shows the actual pressure value. When you enter a pressure value, the
values for flow and average linear velocity are calculated and displayed.
Flow If you enter a flow (in mL/min) here, pressure and velocity are
calculated and adjusted.
Velocity If you enter average linear velocity (in cm/sec), pressure and
flow are calculated.
Mode: There are four column modes: constant flow, constant pressure,
ramped flow, and ramped pressure. To change the mode, scroll to Mode :
and press [Mode/Type].
The “Flow and Pressure Control” chapter of the General Information
volume explains how to set pressure and flow programs.
7
Inlets
Figure 1.
Column display — defined capillary columns
Press [Col 1] or [Col 2]
Carrier gas type
Column dimensions
Actual pressure
COLUMN 1 (He)
Dim
30.0 m 320 u
Pressure
10.0
10.0
Flow
0.8
Velocity
25
Mode: Constant flow
Pressure setpoint
Column flow (mL/min)
— actual and setpoint
Calculated average
linear velocity
(cm/sec)
— actual and setpoint
Press [Mode/Type]
COLUMN 1 MODE
Constant pressure
*Constant flow
<
Ramped pressure
Ramped flow
Mode: Your control table also has one of these,
depending on Mode:
Mode: Const flow
Mode:Ramped flow
Init flow
Init time
Rate 1
Final flow 1
Final time 1
Rate 2 (Off)
8
Mode: Const pressure
<
<
4.0
2.0
0.5
8.0
2.0
0.00
<
Mode:Ramped pressure<
Init pressure
10.0
Init time
1.0
Rate 1
1.0
Final pressure125.0
Final time 1
5.0
Rate 2 (Off)
0.00
Inlets
The column control table—packed or undefined capillary columns
If you have not defined your column or if your inlet selection is
Unspecified, your column control table will be similar to Figure 2.
The title This heading identifies the column—Column 1 or Column 2—
and the type of carrier gas configured to the inlet (in parentheses).
Dimensions unknown
column.
This line tells you that you have not defined your
Pressure The split/splitless inlet and the cool on-column inlet are
pressure controlled. Because the column is unknown, flow and average
linear velocity cannot be computed.
The purged packed inlet is flow controlled. The actual pressure is
displayed, but is not controllable by the user.
Mode: You have a choice of three modes if using a split/splitless or cool
on-column inlet—constant pressure, constant flow, and ramped flow. The
packed inlet gives you only the two flow modes—constant and ramped.
The “Flow and Pressure Control” chapter of the General Information
volume explains how to set pressure and flow programs.
9
Inlets
Figure 2.
Column Display — Packed or Undefined Capillary Columns
Split/splitless or cool on-column inlets
COLUMN 1 (He)
Dimensions unknown Pressure
10.0
10.0
Mode: Constant flow
Carrier gas type
Indicates that your column is not
defined
Pressure (in psi, bar, or kPa)
Press [Mode/Type]
COLUMN 1 MODE
Constant pressure
*Constant flow
Ramped pressure
<
Purged packed inlet
COLUMN 1 (He)
Dimensions unknown
Pressure
10.0
Flow
0.0
Off
Mode: Constant flow
Carrier gas type
Indicates that your column is not
defined
Pressure
Flow to inlet, setpoint and actual
Press [Mode/Type]
COLUMN 1 MODE
*Constant flow
<
Ramped flow
10
Inlets
What is gas saver?
Gas saver reduces carrier gas flow from the split vent after the sample is
on the column. Column head pressure and flow rate are maintained,
while purge and split vent flows decrease. Flows—except column
flow—remain at the reduced level until you press [Prep Run].
You can use gas saver in all modes of operation of the Split/Splitless and
PTV inlets and in the split and splitless modes of the Volatiles Interface.
Figure 3.
Gas Saver Operation
Split
mode 50
[Start]
[Prep run]
Gas saver time (3 min)
Regular flow
Run ends
40
Split vent 30
flow
(mL/min) 20
Gas saver
flow
Gas saver flow
10
5
6
7
Time (min)
[Start]
Gas saver time (5 min)
Purge time
[Prep run]
(2 min)
í
Splitless
mode
50
40
Split vent
flow
30
(mL/min)
20
í
0
1
2
3
4
8
Run ends
Purge flow
Gas saver
flow
Gas saver
flow
10
í
í
0
1
2
3
4
5
6
7
Time (min)
8
The pulsed modes of the split/splitless and PTV inlets are similar except
for the pressure pulse starting at [Prep Run] and ending at Pulse time.
The solvent vent mode of the PTV is more complex; see chapter 5 for
details.
11
Inlets
Procedure: Using gas saver
Press [Front Inlet] or [Back Inlet].
Mode:
Split
Temp
24
Off
Pressure
0.0
Off
Split ratio
10
Split flow
0.0
Tot flow
0.0
Off
FRONT INLET (S/SL)
Gas saver
On
Saver flow
20.0
Saver time
2.00
12
1. Turn on gas saver.
2. Set a flow. Must be at least 15 mL/min
greater than the column flow.
3. If in split mode, set after injection time.
In all other modes, set after purge time.
Inlets
Pre Run and Prep Run
With some inlets and operating modes, certain instrument setpoints are
different between runs than during an analysis. To restore the setpoints
for injection, you must place the GC into the Pre Run state.
You must use the Pre Run state when:
- Using gas saver with any inlet.
- Using splitless mode with any inlet.
- Using a pressure pulse mode with any inlet.
- Using the solvent vent mode of the PTV inlet.
- Using the direct or splitless mode of the Volatiles Interface.
There are two ways to begin Pre Run—manually push the [Prep Run]
key before each run or configure the GC to enter the Pre Run state
automatically. The two methods are discussed below and on the next
page.
During the Pre Run state:
- The Pre Run light blinks and Not Ready is on.
- Setpoints change to the correct values for injection.
- Inlet, detector, and oven equilibration times begin.
When all equilibration times expire, the Pre Run light is on steadily.
When all criteria for a run are met, the Not Ready light turns off. The
GC is now ready for sample injection.
The [Prep Run] key
Press the [Prep Run] key before you inject a sample manually. The GC
enters the Pre Run state. When the Pre Run light is steady and the Not
Ready light goes off, begin the analysis.
13
Inlets
Procedure: Auto Prep Run
With most automatic injection systems, you do not need to use the [Prep
Run] key. If your sampler or automation controller (for example, an
integrator or workstation) does not support the [Prep Run] function, you
must set the GC to Auto Prep Run. To do this:
1. Press the [Config] key to view a list of configurable parameters.
2. Scroll to the Instrument parameter and press [Enter].
3. Scroll to Auto prep run and press [On].
CONFIG INSTRUMENT
Serial#US00100001
Auto prep run
On <
F inlet type
None
B inlet type
PP
14
Inlets
Septum purge
The septum purge line is near the septum where the sample is injected.
A small amount of carrier gas exits through this line to sweep out any
bleed.
Each inlet has a different septum purge flow. The GC automatically sets
the purge flow for EPC inlets, but you can measure it from the septum
purge vent at the flow manifold if you like.
Table 5.
Septum Purge Flows
Inlet
Carrier
Septum Purge
Split/splitless, all
modes
He, N2, Ar/5%Me
3 mL/min
H2
6 mL/min
Purged packed
All
1 to 3 mL/min
Cool on-column
He, N2, Ar/5%Me
15 mL/min
H2
30 mL/min
He, N2, Ar/5% Me
3 mL/min
H2
6 mL/min
He, N2, Ar/5%Me
3 mL/min
H2
6 mL/min
PTV
Volatiles interface
Figure 4.
Septum Purge Vents
Split/splitless inlet
PTV inlet
Volatiles interface
Septum purge vent
Purged packed inlet
Cool on-column inlet
Septum purge vent
15
2
Part 1. Using a Split/Splitless Inlet
Standard and high-pressure versions, 18
Septum tightening, 18
Liners, 19
Split mode pneumatics, 21
The control table—split operation, 22
Procedure: Split mode, column defined, 23
Procedure: Split mode, column not defined, 24
Splitless mode pneumatics, 25
The control table—splitless operation, 26
Operating parameters, 27
Procedure: Splitless mode, column defined, 28
Procedure: Splitless mode, column not defined, 29
Pulsed split and splitless modes, 30
The control table—pulsed split mode, 31
Procedure: Pulsed split mode, 32
The control table—pulsed splitless operation, 33
Procedure: Pulsed splitless mode, 34
Part 2. Maintaining a Split/Splitless Inlet
Changing septa, 36
Changing the O-ring, 39
Replacing the inlet base seal, 43
Procedure: Leak checking the gas plumbing, 46
Procedure: Leak checking EPC split/splitless inlet, 47
Procedure: Leak checking nonEPC split/splitless inlet, 51
Procedure: Correcting leaks, 53
Procedure: Cleaning the inlet, 54
The Split/Splitless Inlet
Chapter 2.
The Split/Splitless Inlet
Part 1.
Using a Split/Splitless Inlet
This inlet is used for split, splitless, pulsed splitless, or pulsed split
analyses. You can choose the operating mode from the inlet control table.
The split mode is generally used for major component analyses, while the
splitless mode is used for trace analyses. The pulsed splitless and pulsed
split modes are used for the same type of analyses as split or splitless,
but allows you to inject larger samples.
Standard and high-pressure versions
The standard split/splitless inlet is rated to 120 psi pressure at the gas
supply fitting. It is appropriate for most columns. The high-pressure inlet
is rated to 170 psi pressure—it is useful with very small diameter
capillary columns that offer considerable resistance to gas flow.
To determine the version that you have, press [Front Inlet] or [Back
Inlet], scroll to the Pressure line, and press the [Info] key. The display
will show the pressure range for the inlet—either 1 to 100 psi (for the
standard version) or 1 to 150 psi (for the high-pressure version).
Septum tightening
The septum retainer has an internal spring that applies pressure to the
septum. For inlet pressures up to 100 psi, tighten the retainer until the
C-ring lifts about 1 mm above the top surface. This is adequate for most
situations.
about 1 mm
With higher inlet pressures, tighten the septum retainer until the C-ring
stops turning, indicating that the retainer is in firm contact with the
septum. Then tighten one additional full turn.
18
Split/splitless operation
Liners
Choose liners according to the type of injection you are doing—split or
splitless. Many liners are available and can be ordered from the
Hewlett-Packard Analytical Columns and Supplies Catalog.
Procedure: Changing the liner
Parts list:
-
Liner, HP part no. 19251-60540 (split) or 5062-3587 (splitless)
Tweezers
Septum wrench (HP part no. 19251-00100)
Viton O-ring (HP part no. 5180-4182)
1. Press [Oven] and set the oven to 35EC. When the temperature
reaches setpoint, turn the oven off. Press [Front Inlet] or [Back Inlet]
and turn off the inlet temperature and pressure.
WARNING
Be careful! The inlet fittings may be hot enough to cause burns.
2. Remove the insert retainer nut. Use a septum wrench, if needed.
3. If a liner is present, remove it with tweezers or a similar tool. Be
careful not to chip the liner.
4. Hold the new liner with tweezers, and inspect it. Make sure it is the
correct type for the injection mode you are using—split or splitless.
5. Place a Viton O-ring on the liner about 2 to 3 mm from its top end.
6. Press the liner straight down into the inlet.
Caution
Do not add an O-ring or other seal either at the bottom of the inlet or at
the bottom of the liner; this will damage the inlet and shatter the liner.
7. Replace the insert retainer nut, tightening it to firm finger tightness.
Do not overtighten.
19
Split/splitless operation
Figure 5.
Installing a liner
O-ring
í mm
from top)
Liner
Insert
retainer nut
20
Split/splitless operation
Split mode pneumatics
During a split injection, a liquid sample is introduced into a hot inlet
where it vaporizes rapidly. A small amount of the vapor enters the
column while the major portion exits from the split/purge vent. The ratio
of column flow to split flow is controlled by the user. Split injections are
primarily used for high concentration samples when you can afford to
lose most of the sample out the split/purge vent. It is also used for
samples that cannot be diluted.
Figure 6 shows the pneumatics for this inlet in split mode operation.
Figure 6.
Flow
limiting
frit
Split flow pneumatics
Total flow
control loop
Septum holder Pressure
sensor
FS
Proportional
valve 1
Septum purge
regulator (not
adjustable)
PS
Flow
sensor
Vent
SPR
Column head pressure control loop
Split vent flow
Trap
Purge
valve
open
Proportional
valve 2
To detector
Safety shutdown mode:
Proportional valve 1 closed
Proportional valve 2 open
Purge valve open
21
Split/splitless operation
The control table—split operation
Mode:
The current operating mode—split
Temp
Actual and setpoint inlet temperatures
Pressure
Actual and setpoint inlet pressure
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This line does not appear if
your column is not defined.
Split flow Flow, in mL/min, from the split/purge vent. This line does not
appear if your column is not defined.
Total flow This is the total flow into the inlet, which is the sum of the
split flow, column flow, and septum purge flow. When you change the
total flow, the split ratio and split flow change while the column flow and
pressure remain the same.
Press [Mode/Type]
FRONT INLET (S/SL)
Mode:
Split
Temp
250
250 <
Pressure
10.0
10.0
Split ratio
100
Split flow
76.6
Tot flow
80.3
80.3
Gas saver
On
Saver flow
20.0
Saver time
2.00
22
FRONT INLET MODE
*Split
<
Splitless
Pulsed splitless
If using gas saver, set time after
injection time.
Split/splitless operation
Procedure: Using the split mode with the column defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet]
a. Scroll to Mode: and press [Mode/Type]. Select Split.
b. Set the inlet temperature.
Split ratio =
Split flow
Column flow
c. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow will be calculated for you.
d. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio will be calculated for you.
e. If desired, turn on Gas saver. Set the Saver time after the
injection time. Use the [Prep Run] key (see page 13) before
manually injecting the sample.
Press [Mode/Type]
FRONT INLET (S/SL)
Mode:
Split
Temp
250
250 <
Pressure
10.0
10.0
Split ratio
100
Split flow
76.6
Tot flow
80.3
80.3
Gas saver
On
Saver flow
20.0
Saver time
2.00
FRONT INLET MODE
Split
<
*Splitless
Pulsed split
Pulsed splitless
If using gas saver,
set time after injection
time.
23
Split/splitless operation
Procedure: Using the split mode with the column not defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet]
FRONT INLET (S/SL)
Mode:
Split
Temp
250
250 <
Pressure
10.0
10.0
Tot flow
79.1
79.1
a. Set temperature.
b. Set total flow into the inlet. Measure flow out of the split vent
using a flow meter.
c. Subtract split vent flow and septum purge flow (see page 15 for
nominal septum purge flows by carrier gas type) from Total flow to
get column flow.
Split ratio =
Split flow
Column flow
d. Calculate the split ratio. Adjust as needed.
Septum purge
Split vent
Front of instrument
24
Split/splitless operation
Splitless mode pneumatics
In this mode, the purge valve is closed during the injection and remains
so while the sample is vaporized in the liner and transferred to the
column. At a specified time after injection, the purge valve opens to
sweep any vapors remaining in the liner out the split vent. This avoids
solvent tailing due to the large inlet volume and small column flow rate.
Specify the purge time and purge flow rate in the inlet control table.
If you are using gas saver, the gas saver time should be after the purge
time.
Figure 7.
Splitless Flow Diagram, Pre-Run to Purge Time
Inlet pressure
control loop
Flow
limiting
frit
Flow
sensor
FS
Septum holder
Pressure
sensor
Septum purge
regulator (not
adjustable)
PS
SPR
Vent
Proportional
valve 1
Trap
Purge
valve
closed
Proportional
valve 2
To detector
Safety shutdown mode:
Proportional valve 1 closed
Proportional valve 2 open
Purge valve open
25
Split/splitless operation
The control table—splitless operation
Mode:
The current operating mode—splitless
Temp
Actual and setpoint inlet temperatures
Pressure
Actual and setpoint inlet pressure in psi, bar, or kPa
Purge time The time, after the beginning of the run, when you want the
purge valve to open.
Purge flow The flow, in mL/min, from the purge vent, at Purge time.
You will not be able to specify this value if operating with your column
not defined.
Total flow The Total flow line displays the actual flow to the inlet
during a Pre-run (Pre-run light is on and not blinking) and during a run
before purge time. You cannot enter a setpoint at these times. At all
other times, Total flow will have both setpoint and actual values.
FRONT INLET (S/SL)
Mode:
Splitless
Temp
250
250 <
Pressure
10.0
10.0
Purge time
0.75
Purge flow
15.0
Total flow
77.6
Gas saver
On
Saver flow
20.0
Saver time
2.00
26
If using gas saver, set saver
time after purge flow time.
Split/splitless operation
Operating parameters
A successful splitless injection consists of these steps:
1. Vaporize the sample and solvent in a heated inlet.
2. Use a low flow and low oven temperature to create a
solvent-saturated zone at the head of the column.
3. Use this zone to trap and reconcentrate the sample at the head of the
column.
4. Wait until all, or at least most, of the sample has transferred to the
column. Then discard the remaining vapor in the inlet—which is
mostly solvent—by opening a purge valve. This eliminates the long
solvent tail that this vapor would otherwise cause.
5. Raise the oven temperature to release the solvent and then the
sample from the head of the column.
Some experimentation is needed to refine the operating conditions.
Table 5 provides starting values for the critical parameters.
Table 5.
Splitless Mode Inlet Parameters
Parameter
Allowed Setpoint Range
Suggested Starting
Value
Oven temperature
No cryo, 24EC to 450EC
CO2 cryo, íEC to 450EC
N2 cryo, íEC to 450EC
Oven initial time
0 to 999.9 minutes
Inlet purge time
0 to 999.9 minutes
Liner volume
x2
Column flow
Gas saver time
0 to 999.9 minutes
After purge time
Gas saver flow
15 to 1000 mL/min
15 mL/min greater
than maximum column flow
Û& below solvent
boiling point
| Inlet purge time
27
Split/splitless operation
Procedure: Using splitless mode with the column defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet]
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the inlet temperature.
c. Enter a purge time and a purge flow.
d. If desired, turn Gas saver on. Make certain the time is set after
the purge flow time.
FRONT INLET (S/SL)
Mode:
Splitless
Temp
250
250 <
Pressure
10.0
10.0
Purge time
0.75
Purge flow
15.0
Total flow
77.6
Gas saver
On
Saver flow
20.0
Saver time
2.00
Press [Mode/Type]
FRONT INLET MODE
Split
<
*Splitless
Pulsed split
Pulsed splitless
If using gas saver,
set time after purge flow
time.
3. Use the [Prep Run] key (see page 13)before manually injecting a
sample.
28
Split/splitless operation
Procedure: Using splitless mode with the column not defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet]
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the inlet temperature.
c. Enter a purge time.
d. Set your total flow greater than the column flow plus the septum
purge flow—see page 15—to guarantee adequate column flow.
Press [Mode/Type]
FRONT INLET (S/SL)
Mode:
Splitless
Temp
250
250 <
Pressure
10.0
10.0
Purge time
0.75
Tot flow
77.6
77.6
FRONT INLET MODE
Split
<
*Splitless
Pulsed split
Pulsed splitless
3. Use the [Prep Run] key (see page 13) before manually injecting a
sample.
29
Split/splitless operation
Pulsed split and splitless modes
The pressure pulse modes increase inlet pressure just before the
beginning of a run and returns it to the normal value after a specified
amount of time. The pressure pulse sweeps the sample out of the inlet
and into the column faster, reducing the chance for sample
decomposition in the inlet. If your chromatography is degraded by the
pressure pulse, a retention gap may help restore peak shape.
You must press the [Prep Run] key before doing manual injections in the
pressure pulse mode. See page 13 for details.
You can do column pressure and flow programming when in the pressure
pulse mode. However, the pressure pulse will take precedence over the
column pressure or flow ramp.
Figure 8.
Pressure Pulse and Column Flow or Pressure
Actual
pressure
Pressure
pulse
Pressure (or flow) program
0
30
1
2
3
4
5
Time (min)
6
7
8
Split/splitless operation
The control table—pulsed split mode
Mode:
The current operating mode—pulsed split
Temp
Actual and setpoint inlet temperatures
Pressure Actual and setpoint inlet pressure at the beginning of a run,
ignoring the effect of a pressure pulse. It sets the starting point of a
pressure program or the fixed pressure if a program is not used.
Pulsed pres The inlet pressure you desire at the beginning of a run.
The pressure rises to this setpoint after [Prep Run] is pressed and
remains constant until Pulse time elapses, when it returns to Pressure.
Pulse time
Pressure returns to its normal setpoint at this time.
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This line does not appear if
your column is not defined.
Split flow Flow, in mL/min from the split/purge vent. This line does not
appear if your column is not defined.
Total flow The total flow into the inlet, a sum of the split flow, column
flow, and septum purge flow. If you change the total flow, the split ratio
and split flow change while the column flow and pressure remain the
same. When a pressure pulse is used, total flow increases to keep the
split ratio constant.
FRONT INLET (S/SL)
Mode: Pulsed split
Temp
250
250 <
Pressure
10.0
10.0
Pulsed pres
30.0
Pulse time
1.0
Split ratio
100
Split flow
67.0
Tot flow
70.9
Gas saver
On
Saver flow
20.0
Saver time
3.00
Pressure pulse
setpoints
31
Split/splitless operation
Procedure: Using the pulsed split mode
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet]
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Split.
b. Set the inlet temperature.
c. Enter values for Pulsed Pres and Pulse time.
Split ratio =
Split flow
Column flow
d. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow is calculated for you if the column is
defined.
e. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio is calculated for you if the column is
defined.
f.
Turn Gas saver on, if desired. Make certain the time is set after
Pulse time.
FRONT INLET (S/SL)
Mode: Pulsed split
Temp
250
250 <
Pressure
10.0
10.0
Pulsed pres
30.0
Pulse time
1.0
Split ratio
100
Split flow
67.0
Total flow
77.6
77.6
Gas saver
Off
Press [Mode/Type]
FRONT INLET MODE
Split
<
Splitless
*Pulsed split
Pulsed splitless
3. Press the [Prep Run] key (see page 13) before injecting a sample
manually.
32
Split/splitless operation
The control table—pulsed splitless operation
Mode:
The current operating mode—pulsed splitless
Temp
Actual and setpoint inlet temperatures
Pressure Actual and setpoint inlet pressure at the beginning of a run,
ignoring the effect of a pressure pulse. It sets the starting point of a
pressure program or the fixed pressure if a program is not used.
Pulsed pres The inlet pressure you desire at the beginning of a run.
The pressure rises to this setpoint after [Prep Run] is pressed and
remains constant until Pulse time elapses, when it returns to Pressure.
Pulse time
Pressure returns to its normal setpoint at this time.
Purge time The time, after the beginning of the run, that you wish the
purge valve to open. Set purge time 0.1 to 0.5 minutes before pulse time.
Purge flow The flow, in mL/min, from the purge vent, at Purge time.
The column must be defined.
Total flow This is the total flow into the inlet, representing a total of the
column flow and the septum purge flow.
FRONT INLET (S/SL)
Mode:Pulsed splitless
Temp
250
250 <
Pressure
10.0
10.0
Pulsed pres
30.0
Pulse time
1.6
Purge time
1.5
Purge flow
15.0
Total flow
77.6
Gas saver
On
Saver flow
0.0
Saver time
3.00
Pressure pulse
setpoints
Inlet purge setpoints
33
Split/splitless operation
Procedure: Using the pulsed splitless mode
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet]
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Splitless.
b. Set the inlet temperature.
c. Enter values for Pulsed pres and Pulse time.
d. Enter the Purge time when you wish the purge valve to open. Set
0.1 to 0.5 minutes before Pulse time.
e. If your column is defined, enter a Purge flow.
f.
f your column is defined, turn Gas saver on, if desired. Make
certain the time is set after the purge flow time.
Press [Mode/Type]
FRONT INLET (S/SL)
Mode:Pulsed Splitless
Temp
250
250 <
Pressure
10.0
10.0
Pulsed pres
30.0
Pulse time
1.0
Purge time
0.9
Purge flow
15.0
Total flow
77.6
Gas saver
On
Saver flow
0.0
Saver time
3.00
FRONT INLET MODE
Split
<
Splitless
Pulsed split
*Pulsed splitless
Set purge time 0.1 to 0.5
minutes
before pressure pulse time.
If using gas saver,
set time after purge flow
time.
3. Press the [Prep Run] key (see page 13) before injecting a sample
manually.
34
Split/splitless maintenance
Part 2.
Maintaining a Split/Splitless Inlet
Figure 9.
The Split/Splitless Capillary Inlet
Septum retainer nut
Septum
O-ring
Split vent line
Insert
assembly
Liner
Insulation
Split/splitless inlet body
Retaining nut
Inlet base seal
Washer
Reducing
nut
Insulation
Insulation cup
Ferrule
Column
nut
35
Split/splitless maintenance
Changing septa
If a septum leaks, you will see symptoms such as longer or shifting
retention times, loss of response, and/or loss of column head pressure.
Additionally, signal noise will increase.
The useful lifetime of septa depends upon injection frequency and needle
quality; burrs, sharp edges, rough surfaces, or a blunt end on the needle
decrease septum lifetime. When the instrument is in steady use, daily
septum replacement is recommended.
The type of septa you use will depend on your chromatography needs.
You can order septa directly from Hewlett-Packard; refer to the
Analytical Columns and Supplies Catalog for ordering information.
Table 6.
Recommended Septa for the Split/Splitless Inlet
Description
HP part number
11-mm septum, low-bleed red
5181-1263
11-mm septum with partial through-hole, low-bleed red 5181-3383
WARNING
36
11-mm septum, low-bleed gray
5080-8896
Merlin microseal septum (see page 170)
5181-8815
11-mm high-temperature silicon septum (350EC and
higher)
5182-0739
Be careful! The oven and/or inlet may be hot enough to cause burns.
Split/splitless maintenance
Procedure: Changing the septum
Materials needed:
-
Gloves (if inlet is hot)
New septum—refer to Table 6 on page 36 for part numbers
Septum nut wrench (HP part no. 19251-00100)
A nonmetallic (plastic or wood) tool with a sharp tip to remove
septum from inlet
0- or 00-grade steel wool (optional)
Forceps or tweezers
Compressed, filtered, dry air or nitrogen (optional)
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn the oven off.
- Turn off the detector.
- Cool the inlet to room temperature.
- Turn the inlet pressure off.
- If the inlet is hot, wear gloves to protect your hands from burns.
2. Remove the septum retainer nut, using the wrench if the nut is
hot or sticks. Remove the old septum.
Septum retainer nut
Septum
If the septum sticks, use
the sharp-tipped tool to
remove it. Take care not
to gouge the metal
around the septum, and
remove all pieces of the
old septum.
37
Split/splitless maintenance
3. If pieces of the septum are
sticking, grasp a small piece of
rolled-up 0- or 00-grade steel
wool with the forceps (or
tweezers) and scrub the residue
from the retainer nut and
septum holder. Use the
compressed air or nitrogen to
blow away the pieces of steel
wool and septum.
4. Use the forceps to insert a new
septum. Press it into the fitting
firmly.
Insert septum here
5. Replace the septum retainer nut, tightening it finger-tight until the
C-ring is approximately 1 mm above the nut. When the nut is replaced,
you can restore normal operating conditions.
C-ring
Septum
retainer
nut
38
1 mm
between nut
and C-ring
Do not overtighten the
nut! Over-tightening overcompresses the septum,
which causes premature
failure and pieces of
septum to fall in the inlet.
Split/splitless maintenance
Changing the O-ring
You will need to change the O-ring each time you change the liner, or if
it wears out and becomes a source of leaks in the inlet. To determine if
the O-ring leaks, run the leak test for the split/splitless inlet.
O-rings contain plasticizers that give them elasticity. The O-ring seals
the top of the inlet, the inlet base, and the liner. However, at high
temperatures the plasticizers bake out, and the O-rings become hard and
are no longer able to create a seal (this is referred to as “taking a set”).
Figure 10.
Cross Section of Inlet, Liner, and O-ring.
Liner
Liner
O-ring
O-ring
Inlet
base
Inlet
base
New O-ring
Worn
O-ring
39
Split/splitless maintenance
If you regularly operate the inlet at high temperatures, you may want to
use graphite O-rings. Although they have a longer life-time, they too will
eventually take a set. Refer to the table below to make sure you are
using the correct O-ring for your inlet.
Table 7.
WARNING
40
O-Rings for the Split/Splitless Inlet
Description
HP Part Number
Viton O-ring for temperatures up to 350EC
5181-4182
Graphite O-ring for split liner (temperatures above
350EC)
5180-4168
Graphite O-ring for splitless liner (temperatures above
350EC)
5180-4173
Be careful! The oven and/or inlet may be hot enough to cause burns. If
the inlet is hot, wear gloves to protect your hands.
Split/splitless maintenance
Procedure: Changing the O-ring
Materials needed:
-
Gloves (if inlet is hot)
A new O-ring—refer to Table 7 on page 40
Septum nut wrench (HP part no. 19251-00100)
Forceps or tweezers
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn the oven off.
- Turn off the detector.
- Cool the inlet to room temperature.
- Turn the inlet pressure off.
- Wear gloves if the inlet is hot to protect your hands from burns.
2. Locate the split/splitless insert
nut, and loosen it using the
wrench if necessary. Lift it
straight up to avoid chipping or
breaking the liner.
Split/splitless
insert nut
3. You should see the top of the liner
with the O-ring around it. Using
the forceps (or tweezers), grasp the
liner and pull it out.
Liner and
O-ring in inlet
41
Split/splitless maintenance
4. Replace the old O-ring with a
new one.
5. Using the forceps, return the liner
to the inlet, replace the insert
assembly nut, and use the wrench
to tighten the nut just to snugness.
Slide new O-ring onto the liner
6. Restore the GC to normal operating conditions.
42
Split/splitless maintenance
Replacing the inlet base seal
You must replace the inlet base seal whenever you loosen or remove the
reducing nut. In addition, chromatographic symptoms such as ghost
peaks indicate that the inlet base seal is dirty and should be replaced.
Two types of inlet base seals are available:
- Gold-plated seal, HP part number 18740-20885
- Stainless steel seal, HP part number 18740-20880
You change the inlet base seal from inside the oven, so you must remove
the column. If you are unfamiliar with column installation and removal,
see the “Columns and Traps” chapter in the General Information
volume.
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
43
Split/splitless maintenance
Procedure: Replacing the inlet base seal
Materials needed:
-
Clean, lint-free, non-nylon gloves (must wear when handling seal)
A new seal (see page 43 for part numbers)
A new washer (HP part no. 5061-5869)
1/4-in. wrench (for column)
1/2-in. wrench
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn the oven off.
- Turn off the detector.
- Cool the inlet to room temperature.
- Turn the inlet pressure off.
2. Remove the column from the inlet. Cap the open end of the column to
prevent contamination. If an insulation cup is installed around the base of
the inlet, remove it.
Reducing nut
44
Disconnected,
capped column
Split/splitless maintenance
3. Use the 1/2-in. wrench to loosen the reducing nut, and then remove it.
The washer and seal are inside the reducing nut. Remove them. You will
probably want to replace the washer when you replace the inlet seal.
Reducing nut
4. Put on the golves to protect the inlet base seal and washer from
contamination. Place the washer in the reducing nut. Place the new
inlet base seal on top of it.
Inlet base seal
Washer
Reducing nut
Side view of
inlet base seal:
Make sure
this raised
portion faces
down.
5. Replace the reducing nut. Use the 1/2-in. wrench to tighten the nut.
Replace the column and the insulation cup. If you are not sure how to do
so, see the General Information volume. After the column is installed,
you can restore normal operating conditions.
45
Split/splitless maintenance
Procedure: Leak testing the gas plumbing
Leaks in the gas plumbing can affect chromatographic results
dramatically. The following procedure checks the flow system up to but
not including the inlet flow manifold. If this portion of the system proves
to be leak-free, refer to the next procedure to check the inlet and inlet
manifold.
Liquid leak detectors are not recommended, especially in areas where
cleanliness is very important.
If you do use leak detection fluid, immediately rinse the fluid off to
remove the soapy film.
WARNING
To avoid a potential shock hazard when using liquid detection fluid, turn
the GC off and disconnect the main power cord. Be careful not to spill
leak solution on electrical leads, especially the detector heater leads.
Materials needed:
- Electronic leak detector capable of detecting your gas type or liquid
-
leak detection fluid. If you use leak detection fluid, remove excess
fluid when you have completed the test.
Two 7/16-in. wrenches
1. Using the leak detector, check
each connection you have made
for leaks.
46
2. Correct leaks by tightening the
connections. Retest the
connections; continue tightening
until all connections are
leak-free.
Split/splitless maintenance
Procedure: Leak testing an EPC split/splitless inlet
There are numerous places in the inlet that can leak. This procedure lets
you determine, in general, if there is an unacceptable leak in the inlet.
If the inlet is leaking, you should use an electronic leak detector to
pinpoint the component that is leaking.
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
Materials needed:
-
No-hole ferrule
7/16-in. wrench
Gloves (if the inlet is hot)
Septum nut wrench (HP part no. 19251-00100)
9/16-in. wrench
1/4-in. SWAGELOK cap
Bubble flow meter
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn it off.
- When the oven is cool, turn off the inlet pressure.
- Remove the column, if one is installed, and plug the column fitting
with the column nut and a no-hole ferrule.
- Remove the old septum and replace it with a new one. For instructions,
see “Changing Septa” on page 36.
- Inspect the O-ring and replace it if it is hard and brittle or cracked. See
page 40 for instructions.
47
Split/splitless maintenance
2. Cap the septum purge fitting with a 1/4-in. SWAGELOK cap.
Capped septum
purge fitting
3. Set the oven to its normal operating temperature. Set the inlet to its
normal operating temperature. Enter a pressure setpoint between 20 and
25 psi, or enter your normal operating pressure if it is greater. Make sure
that the pressure at the gas supply is at least 10 psi higher than the inlet
pressure.
Press [Front
Inlet] or [Back
Inlet]
48
FRONT INLET (S/SL)
Mode
Split
Temp
150 150
Pressure
0.0 24.0<
Split ratio
25.0
Split flow
0.0
Total flow
0.0 Off
Gas saver
Off
Split/splitless maintenance
4. Set the total flow to 60 ml/min. Wait a few moments for the pressure
and flow to equilibrate.
Press [Front
Inlet] or [Back
Inlet]
The GC may
exceed the
pressure setpoint
slightly while
equilibrating.
FRONT INLET (S/SL)
Mode
Split
Temp
150 150
Pressure
24.2 24.0<
Split ratio
25.0
Split flow
0.0
Total flow
60.0 60.0
Gas saver
Off
5. Verify that the flow is actually 60 ml/min by measuring the flow rate at
the split purge vent on the manifold. Use a bubble flow meter to
measure the flow.
Measure flow at this fitting
49
Split/splitless maintenance
6. Turn either the pressure or the flow off. Because the septum purge and
the column fittings are capped, gas should be trapped in the system and
the pressure should remain fairly constant.
Press [Front
Inlet] or [Back
Inlet]
FRONT INLET (S/SL)
Mode
Split
Temp
150 150
Pressure
24.0 Off <
Split ratio
6.8
Split flow
0.0
Total flow
0.0 Off
Gas saver
Off
Because the pneumatics have been turned off, the alarm does not sound
even though there is no flow through the column.
7. Continue to monitor pressure for 10 to 15 minutes. You can use the GC’s
Stopwatch function. A pressure drop of 0.03 psi/min or less is acceptable.
Press [Time]
9:56:08
12 Dec 94
Last runtime
Next runtime
t = 0:04.9
1/t = 12.24
0.00
999.99
If the pressure drop is 0.03 psi/min or less, you can consider the inlet
leak-free.
If the pressure drops faster than the acceptable rate, see “Correcting
Leaks” on page 53.
50
Split/splitless maintenance
Procedure: Leak testing a nonEPC split/splitless inlet
There are numerous places in the inlet that can leak. This procedure lets
you determine, in general, if there is an unacceptable leak in the inlet.
If the inlet is leaking, you should use an electronic leak detector to
pinpoint the component that is leaking.
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
Materials needed:
-
No-hole ferrule
7/16-in. wrench
Gloves (if the inlet is hot)
Septum nut wrench (HP part no. 19251-00100)
9/16-in. wrench
1/8-in. SWAGELOK cap
Bubble flow meter
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose,
store them as a method.
- Cool the oven to room temperature and then turn it off.
- When the oven is cool, turn off the inlet pressure.
- Remove the column, if one is installed, and plug the column
fitting with the column nut and a no-hole ferrule.
- Remove the old septum and replace it with a new one. For
instructions on changing septa, see page 36.
- Inspect the O-ring and replace it if it is hard and brittle or
cracked. See page 40 for instructions.
2. Cap the purge vent with a 1/8-in. SWAGELOK cap.
3. Set the oven to its normal operating temperature.
4. Set the inlet to its normal operating temperature. Make sure that the
pressure at the initial gas supply is at least 35 psi.
51
Split/splitless maintenance
5. Set the inlet pressure between 20 and 25 psi, or to your normal
operating pressure, if it is higher. Set the split flow to 60 ml/min.
Wait a few moments for the pressure and flow to equilibrate.
6. Verify that the septum purge is off by using a bubble flow meter.
7. Turn off flow to the inlet by turning off the carrier gas at the flow
controller. Then, adjust the back pressure regulator clockwise and additional 1/4 turn.
Observe the column pressure for approximately 15 minutes. If the
pressure remains between 19 and 20 psi, or if the pressure drop is
0.03 psi/min or less, you can consider the inlet leak-free.
If the pressure drops faster than the acceptable rate, go to the next
section, “Correcting Leaks.”
52
Split/splitless maintenance
Procedure: Correcting leaks
Materials needed:
- Electronic leak detector
- Tools to tighten connections
1. Use the electronic leak detector to check all areas of the inlet that are
potential sources of a leak. Potential leak areas are:
-
The
The
The
The
The
The
The
capped purge vent
plugged column connection
septum and/or septum nut
area where the gas lines are plumbed to the inlet
O-ring
O-ring nut
inlet base seal
2. Correct leaks using the correct size wrench to tighten connections.
You may need to repeat the leak test again to check for leaks.
If the pressure drop is now 0.03 psi/min or less, you can consider the
inlet system leak-free.
If the pressure drops faster than this, continue to search for leaks
and repeat the pressure test. If all fittings appear to be leak free, but
the inlet system is still losing too much pressure, you may need to
replace the inlet manifold. Contact your Hewlett-Packard service
representative.
53
Split/splitless maintenance
Procedure: Cleaning the inlet
It is unlikely that the inlet will frequently require the thorough cleaning
that this procedure presents; however, deposits from injected samples
occasionally build up inside the split/splitless inlet. Before cleaning the
inlet, replace dirty column liners and inserts with clean ones. If changing
them does not correct the problems, then clean the inlet.
Materials needed:
- Cleaning brushes—The FID cleaning kit contains appropriate
-
brushes
(HP part no. 9301-0985)
Solvent that will clean the type of deposits in your inlet
Compressed, filtered, dry air or nitrogen
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the heated zones to room temperature. Turn them off when they
cool.
- Turn off all flows to the inlet at the initial gas supply.
- Turn off the GC and unplug it.
- Remove the liner.
- Remove the column and the column liner. See the “Columns and
Traps” chapter in the General Information volume.
- Remove the inlet base seal. See page 43 for instructions.
2. Using a suitable light source, illuminate the inside of the inlet from
inside the oven and look for signs of contamination or deposits. Insert
the brush into the inlet. Scrub the interior walls of the inlet vigorously
to remove all deposits.
54
Split/splitless maintenance
4. Dry thoroughly with the compressed air or nitrogen before reassembling.
You can also use compressed air to blow out any loose particles.
Caution
To avoid eye injury, wear eye protection when
using compressed gas.
5. Reassemble the inlet. You must replace the inlet base seal at this time.
You should replace the septum with a new one. Plug in the GC’s power
cord, turn it on, and restore it to normal operating conditions.
55
3
Part 1. Using a Purged Packed Inlet
Liners and inserts, 59
Procedure: Installing liners, 61
Procedure: Installing glass inserts, 63
The control table, 65
Packed columns or column not defined, 65
Defined capillary columns, 65
Procedure: Using packed and undefined capillary columns, 66
Procedure: Using defined capillary columns, 66
Part 2. Maintaining a Purged Packed Inlet
Procedure: Changing septa, 68
Procedure: Changing the O-ring, 72
Procedure: Leak checking the gas plumbing, 74
Procedure: Leak checking an EPC purged packed inlet, 75
Procedure: Leak checking a nonEPC purged packed inlet, 78
Procedure: Correcting leaks, 80
Procedure: Cleaning the inlet, 81
The Purged Packed Inlet
Chapter 3.
The Purged Packed Inlet
Part 1.
Using a Purged Packed Inlet
This inlet is used with packed columns when high-efficiency separations
are not required. It can also be used with wide-bore capillary columns,
provided that flows greater than 10 mL/min are acceptable.
If a capillary column is used and the column is defined, the inlet is
pressure-controlled. If the column is not defined (packed columns and
undefined capillary columns), the inlet is flow-controlled.
Figure 11.
Packed Column Inlet with Electronic Pneumatics Control
Flow-controlled mode (recommended for
packed columns)
Flow
limiting
frit
Proportional Flow
valve
sensor
FS
Pressure
sensor
Septum purge
Septum holder regulator
(not adjustable)
PS
SPR
Purge Vent
Flow
Total flow
control loop
To column
and detector
Pressure-controlled mode (recommended for capillary columns)
Flow
limiting
frit
Proportional Flow
valve
sensor
FS
Pressure
sensor
Septum holder
PS
SPR
Inlet pressure
control loop
To column
and detector
58
Septum purge
regulator (not
adjustable)
Purge Vent
Flow
Purged packed operation
Liners and inserts
Liners. Your choice of liner depends on the type of column you are using.
Liners are available for use with wide-bore capillary, 1/4-in. packed, or
1/8-in. packed columns. The liner functions as an adapter so that
columns can be connected to the inlet. Installation instructions are on
page 61.
Inserts. Glass inserts are often used with metal liners to reduce
reactivity and trap nonvolatile residues. They are always used with
capillary columns. Inserts are installed from the top of the inlet and
should be installed before the column. Installation instructions are on
page 63.
The purged packed inlet is shipped with a liner and insert for use with
capillary columns (see Table 8.) If you are using packed columns, consult
Table 9.
Table 8. Liner and Insert for Wide-Bore Capillary Columns
(Narrow-bore capillary columns are not recommended for use with this inlet.)
Column type
Liner
Insert
530 mm or
320 mm
19244-80540
5080-8732 or
5181-3382*
1/4-in
Vespel ferrule
1/4-in nut
Capillary
C
ill
liner
*Deactivated
59
Purged packed operation
Table 9.
Liner and Insert for Packed Columns
Column Type
Liner
Insert
1/8-in. metal
1/8-in. stainless steel
19243-80510
None
19243-80530
1/4-in. metal
1/4-in. glass
1/4-in. stainless steel
19243-80520
5080-8732 or
5181-3382*
none
19243-80540
5080-8732 or
5181-3382*
No liner required.
Column end
functions as liner.
Can also use 1/4-in.
metal liner.
Not applicable
*Deactivated
1/4- or 1/8-inch liner
(stainless steel)
Insert
1/4-in. Vespel
ferrule
1/4-in.
nut
1/8-in. or 1/4-in.
stainless steel
liner
60
Purged packed operation
Procedure: Installing liners
Use these instructions for installing all liner types. Graphitized Vespel
ferrules are recommended because metal ferrules tend to lock
permanently onto the liner. If a leak develops when using metal ferrules,
you must replace the entire liner.
Materials needed:
-
Liner, brass nut, and ferrule (see Table 8 or Table 9)
Lint-free cloth
Methanol
9/16-in. wrench
1. Press [Oven] and set the oven to 35EC. When the temperature
reaches setpoint, turn the oven off. Press [Front Inlet] or [Back Inlet]
and turn off the inlet temperature and pressure or flow.
WARNING
Be careful. The oven and inlet fittings may be hot enough to cause
burns.
2. Clean the end of the liner with a lint-free cloth to remove
contamination such as fingerprints. Use methanol as a solvent.
3. Place a brass nut and graphitized Vespel ferrule on the liner.
4. Open the oven door and locate the inlet base. Insert the liner straight
into the inlet base as far as possible.
5. Hold the liner in this position and tighten the nut finger tight.
6. Use a wrench to tighten the nut an additional 1/4 turn.
7. Install the column.
8. Establish a flow of carrier gas through the inlet, and heat the oven
and inlet to operating temperatures. Allow these to cool, and then
retighten the fittings.
61
Purged packed operation
Figure 12.
Installing a Liner
Inlet
fitting
Graphitized
Vespel
ferrule
Brass
nut
Liner
62
Purged packed operation
Procedure: Installing glass inserts
Materials needed:
- Insert (see Table 8 or Table 9)
- Tweezers or hemostats
- Wire
1. Press [Oven] and set the oven to 35EC. When the temperature
reaches setpoint, turn the oven off. Press [Front Inlet] or [Back Inlet]
and turn off the inlet temperature and pressure or flow.
WARNING
Be careful. The inlet fittings may be hot enough to cause burns.
2. Remove the knurled nut at the top of the inlet.
3. Carefully remove the old insert. A thin wire (such as a paper clip)
may be helpful when lifting the insert from the inlet.
4. Using tweezers or similar tool, grasp the top of the insert and install
in the inlet with the flared end up.
5. If a capillary column is installed and the insert does not seat
properly, you must remove the capillary column, install the insert,
and replace the column.
6. Reinstall the knurled nut and tighten finger tight.
63
Purged packed operation
Figure 13.
Installing a Glass Insert in a Purged Packed Inlet
Knurled nut
Insert
64
Purged packed operation
The control table
Packed columns or column not defined
(The inlet)
FRONT INLET (PP)
Temp
24
Off
Pressure
0.0
Tot flow
0.0
Off
Temp
(The column)
COLUMN 1 (He)
Dimensions unknown
Pressure
0.0
Flow
0.0
Off
Mode: Constant flow
The setpoint and actual temperature values.
Pressure The actual pressure (in psi, bar, or kPa) supplied to the inlet.
You cannot enter a setpoint here.
Tot flow Enter your setpoint here, actual value is displayed. Inlet is
mass flow controlled.
Defined capillary columns
(column defined)
FRONT INLET (PP)
Temp
24
Off
Pressure
0.0
Off
Tot flow
0.0
Temp
The setpoint and actual temperature values
Pressure Inlet is pressure controlled. Enter your setpoint here (in psi,
bar, or kPa) and actual value is displayed.
Tot flow The actual total flow to the inlet. This is a reported value, not
a setpoint.
65
Purged packed operation
Procedure: Using packed and undefined capillary columns
If the column is not defined, only the flow-controlled modes are available.
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet] and enter a temperature. (The flow
was set at the column in step 4.)
FRONT INLET (PP)
Temp
24
Off
Pressure
0.0
Tot flow
0.0
Off
3. Inject a sample.
Set column flow from the Column table, as described in Appendix A.
Total flow in the inlet table is the sum of column flow and septum purge
flow.
Procedure: Using defined capillary columns
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet] and enter a temperature.
FRONT INLET (PP)
Temp
24
Off
Pressure
0.0
Off
Tot flow
Off
3. Inject the sample.
66
Purged packed maintenance
Part 2.
Maintaining a Purged Packed Inlet
Figure 14.
The Purged Packed Inlet
Insullation
Septum nut
Septum
Knurled nut
O-ring
Heater/sensor
assembly
Purged packed
inlet body
Insullation
Insullation
Insullation
cup
Ferrule
Column
nut
67
Purged packed maintenance
Procedure: Changing septa
If the septum leaks, you will see symptoms such as longer or shifting
retention times, loss of response, and/or loss of column head pressure.
Additionally, the detector signal will become increasingly noisy.
The useful lifetime of septa is determined by injection frequency and
needle quality; burrs, sharp edges, rough surfaces, or a blunt end on the
needle decrease septum lifetime. When the instrument is used regularly,
daily septum replacement is recommended.
The type of septa you use will depend on your chromatography needs.
You can order septa directly from Hewlett-Packard; see the Analytical
Columns and Supplies Catalog for ordering information.
Table 10.
Recommended Septa for the Purged Packed Inlet
Description
HP Part Number
11-mm septum, low-bleed red
5181-1263
11-mm septum with partial through-hole, low-bleed red 5181-3383
11-mm septum, low-bleed gray
5080-8896
Merlin microseal septum
5181-8815
11-mm high-temperature silicon septum (350EC and
higher)
5182-0739
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
Caution
Column flow is interrupted while changing septa; since columns may be
damaged at elevated temperatures without carrier flow, cool the oven to
room temperature before proceeding.
68
Purged packed maintenance
Materials needed:
-
Gloves (if the inlet is hot)
New septum—see Table 10 on page 68 for part numbers
Septum nut wrench (HP part no. 19251-00100)
A nonmetallic (plastic or wood) tool with a sharp tip to remove
septum from inlet
0- or 00-grade steel wool (optional)
Forceps or tweezers
Compressed, filtered, dry air or nitrogen (optional)
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn the oven off.
- Turn off the detector.
- Cool the inlet to room temperature.
- Turn the inlet pressure off.
Caution
If you are using packed columns, decrease head pressure
to prevent a sudden release of inlet pressure from blowing
the packing out of the column.
69
Purged packed maintenance
2. If the inlet is hot, wear the gloves to protect your hands from burns.
Remove the septum retainer nut, using the wrench to loosen or remove
the nut if it is hot or sticks. Remove the old septum.
Septum retainer nut
Septum
If the septum sticks, use the
sharp-tipped tool to remove it.
Take care not to gouge the
metal around the septum and
to remove all pieces of the old
septum.
3. If pieces of the septum are
sticking, grasp a small piece of
rolled-up 0- or 00-grade steel wool
with the forceps (or tweezers), and
scrub the residue from the
retainer nut and septum holder.
Use the compressed air or
nitrogen to blow away the pieces
of steel wool and septum.
70
4. Use the forceps to insert a new
septum. Press it into the
fitting firmly.
Insert new
septum
here
Purged packed maintenance
5. Replace the septum retainer nut, tightening it finger-tight until the
C-ring is approximately 1 mm above the nut. When the nut is tightened,
you can restore normal operating conditions.
C-ring
Septum
retainer nut
1 mm between
nut and C-ring
Do not overtighten the nut!
Over-tightening overcompresses the septum,
which could cause
premature failure and
pieces of septum to
contaminate the inlet.
71
Purged packed maintenance
Procedure: Changing the O-ring
You will need to change the O-ring periodically because it wears out and
becomes a source of leaks in the inlet. To determine if the O-ring leaks,
perform the leak test presented later in this chapter.
O-rings contain plasticizers that give them elasticity. The O-ring seals
the top of the inlet and the inlet base. However, at high temperatures
the plasticizers bake out, and the O-rings become hard and are unable to
create a seal (this is referred to as “taking a set”). If you operate the inlet
at high temperatures, you will probably need to replace the O-ring
frequently.
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
If the inlet is hot, be sure to wear gloves to protect your hands.
Materials needed:
-
Gloves (if the inlet is hot)
A new Viton O-ring (HP part no. 5080-8898)
Septum nut wrench (HP part no. 19251-00100)
Forceps or tweezers (optional)
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn the oven off.
- Turn off the detector.
- Cool the inlet to room temperature.
- Turn the inlet pressure off.
Caution
If you are using packed columns, decrease head
pressure to prevent a sudden release of inlet pressure
from blowing the packing out of the column.
72
Purged packed maintenance
2. If the inlet is hot, use the septum
nut wrench. Loosen the knurled
nut completely. Pull up on the
nut to remove the top portion of
the inlet.
3. The O-ring will be visible.
Remove the old O-ring. You may
need to use forceps to grab it.
Using the tweezers, insert the
new O-ring.
Pulling up on the
knurled nut
removes entire top
of inlet.
Knurled nut
O-ring
4. Replace the top portion of the inlet and tighten the knurled nut until you
cannot tighten it further. Restore the GC to normal operating conditions.
73
Purged packed maintenance
Procedure: Leak testing the gas plumbing
Leaks in the gas plumbing system can affect chromatographic results
dramatically. The following procedure checks the flow system up to but
not including the inlet flow manifold. If this portion of the system proves
to be leak-free, refer to the next procedure to check the inlet and inlet
manifold.
Liquid leak detectors are not recommended, especially in areas where
cleanliness is very important.
If you do use leak detection fluid, immediately rinse the fluid off to
remove the soapy film.
WARNING
To avoid a potential shock hazard when using liquid detection fluid, turn
the GC off and disconnect the main power cord. Be careful not to spill
leak solution on electrical leads, especially the detector heater leads.
Materials needed:
- Electronic leak detector or liquid leak detection fluid. If you use leak
-
detection fluid, wipe off excess fluid when you have completed the
test.
Two 7/16-in. wrenches
1. Using the leak detector, check
each connection you have made
for leaks.
74
2. Correct leaks by tightening the
connections. Retest the
connections; continue tightening
until all connections are
leak-free.
Purged packed maintenance
Procedure: Leak testing an EPC purged packed inlet
This procedure allows you to determine if the inlet is leaking. It is
recommended that you leak test the inlet at your normal operating
temperature since the O-ring may leak if it is cooled to ambient.
Materials needed:
- Gloves (if the inlet is hot)
- Septum nut wrench (HP part no. 19251-00100)
If you are using capillary columns:
- No-hole ferrule
- 7/16-in. wrench
If you are using packed columns:
- Solid Vespel plug
- 9/16-in. wrench
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn it off.
- When the oven is cool, turn off the inlet pressure.
- Remove the column, if one is installed, and cap the column fitting.
If you are using capillary columns, insert a no-hole ferrule in the
column nut to create a plug.
If you are using packed columns, use the Vespel plug.
- Remove the old septum and replace it with a new one. For instructions
on changing septa, see “Changing Septa” on page 68.
- Inspect the O-ring and replace it if it is hard and brittle or cracked. See
page 72 for instructions on changing the O-ring.
- Make sure that the pressure at the initial gas source is at least 35 psi.
75
Purged packed maintenance
2. Set the inlet to its normal operating temperature.
Press [Front
Inlet] or [Back
Inlet]
FRONT INLET (pp)
Temp
150 150 <
Pressure
0.0 Off
Total flow
0.0
3. Set the inlet pressure between 20 and 25 psi.
Press [Front
Inlet] or [Back
Inlet]
FRONT INLET (pp)
Temp
24 Off
Pressure
0.0 24.0<
Total flow
0.0
4. Wait a few minutes for the pressure to equilibrate.
Press [Front
Inlet] or [Back
Inlet]
The GC may
exceed the
pressure setpoint
slightly while
equilibrating.
76
FRONT INLET (pp)
Temp
24 Off
Pressure
24.2 24.0<
Total flow
0
Purged packed maintenance
6. Turn the pressure off. Because the column is capped, the pressure
should remain fairly constant.
Press [Front
Inlet] or [Back
Inlet]
FRONT INLET (pp)
Temp
24 Off
Pressure
24.0 Off<
Total flow
0.0
Because the pneumatics have been turned off, the alarm does not sound
even though there is no flow through the column.
7. Continue to monitor pressure for 10 to 15 minutes. You can use the GC’s
Stopwatch function. A pressure drop of 0.03 psi/min or less is acceptable.
Press [Time]
9:56:08
12 Dec 94
Last runtime
Next runtime
t = 0:04.9
1/t = 12.24
0.00
999.99
If the pressure drop is 0.03 psi/min or less, you can consider the inlet
system leak-free.
If the pressure drops faster, go to “Correcting Leaks” on page 80.
77
Purged packed maintenance
Procedure: Leak testing a nonEPC purged packed inlet
This procedure allows you to determine if the inlet leaks. It is
recommended that you leak test the inlet at your normal operating
temperature since the O-ring is likely to leak if it is cooled to ambient.
Materials needed:
- Gloves (if the inlet is hot)
- Septum nut wrench (HP part no. 19251-00100)
- 1/8 in. SWAGELOK cap (HP part no. 5180-4120)
If you are using capillary columns:
- No-hole ferrule
- 7/16-in. wrench
If you are using packed columns:
- Solid Vespel plug
- 9/16-in. wrench
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose,
store them as a method.
- Cool the oven to room temperature and then turn it off.
- When the oven is cool, turn off the inlet pressure.
- Remove the column, if one is installed, and cap the column fitting.
-
78
If you are using capillary columns, insert a no-hole ferrule in
the column nut and then attach the nut to the fitting.
If you are using packed columns, attach the Vespel plug to the
fitting.
Remove the old septum and replace it with a new one. For
instructions on changing septa, see “Changing Septa” on page 68.
Inspect the O-ring, and replace it if it is hard and brittle or
cracked. See page 72 for instructions on changing the O-ring.
Purged packed maintenance
2. Set the inlet to its normal operating temperatures.
3. Cap the septum purge vent with a 1/8-in. SWAGELOK cap.
4. Turn on the gas to the inlet at its source and adjust the supply
pressure to 50 psi. Completely open the mass flow controller by
turning the knob counterclockwise as far as it can go. Wait 2 minutes
to insure equilibrium.
5. Turn off the gas to the inlet at its source. Monitor the pressure for 10
to 15 minutes. You can use the GC’s Stopwatch function. A pressure
drop of 0.03/min psi or less is acceptable.
If the pressure drop is 0.03 psi/min or less, you can consider the inlet
leak-free.
If the pressure drops faster than this, go to “Correcting Leaks” on
page 80.
79
Purged packed maintenance
Procedure: Correcting leaks
Materials needed:
- Electronic leak detector suitable for the gas type
- Tools to tighten parts of the inlet that leak (if leaks are detected)
1. Use the leak detector to check all areas of the inlet that are potential
sources of a leak. Potential leak areas are:
- The septum and/or septum nut
- The 1/4-in. ferrule (if a liner is being used)
- The O-ring
- The capped purge vent
- The plugged column connection
- The knurled nut
- The area where the gas line is plumbed to the inlet
If no liner is used, then column must be plugged with 1/4-in.
cap or equivalent
SWAGELOK
2. Correct leaks using a wrench to tighten loose connections, if
necessary. You may need to repeat the leak test.
If the pressure drop is now 0.03 psi/min. or less, you can consider the
inlet leak-free.
If the pressure drops faster than the acceptable rate, continue to
search for leaks and repeat the pressure test. If all fittings appear to
be leak free, but the inlet is still losing too much pressure, you may
need to replace the inlet manifold. Contact your Hewlett-Packard
service representative.
80
Purged packed maintenance
Procedure: Cleaning the inlet
It is unlikely that the inlet will frequently require cleaning as thoroughly
as this procedure presents; however, deposits from injected samples
occasionally build up inside the purged packed inlet. Before cleaning the
inlet, replace dirty column liners and inserts with clean ones. See the
Inlets volume for instructions. If changing them does not correct the
problems, then clean the inlet.
Materials needed:
- Cleaning brushes—The FID cleaning kit contains appropriate
-
brushes
(HP part no. 9301-0985)
Solvent that will clean the type of deposits in your inlet
Compressed, filtered, dry air or nitrogen
1. Complete the following
preliminary steps:
- If you have entered
parameters that you do not
want to lose, store them as a
method.
- Allow the heated zones to cool.
- Turn off all flows to the inlet at
the initial gas supply.
- Turn off the GC and unplug it.
- If the septum is worn out or
dirty, replace it. See page 68
for instructions.
- Remove the column and the
column liner and insert. See
the “Columns and Traps”
chapter in the General
Information volume.
2. Loosen the knurled nut and
then pull it upward. The O-ring
will be visible. Replace it if it is
hard and brittle or cracked. See
page 72 for the procedure.
Pulling up on the
knurled nut
removes entire top
of inlet.
O-ring
81
Purged packed maintenance
3. Using a suitable light source, illuminate the inside of the inlet from
inside the oven while looking through the inlet from the top. If
deposits are present, they should be visible.
4. Insert the brush into the inlet. Scrub the interior walls of the inlet
vigorously to remove all deposits. You may need to wet the brush with
solvent. Use a burst of the compressed air or nitrogen to dry the inlet
and remove loose contaminants.
WARNING
To avoid eye injury, wear eye
protection when using compressed gas.
5. Replace the top of the inlet and tighten the knurled nut. Replace the
column (the procedure is in the General Information volume).
6. Plug in the GC’s power cord, turn it on, and restore it to normal
operating conditions.
82
4
Part 1. Using a Cool On-Column Inlet
Hardware, 85
Automatic or manual injection with septum nut, 87
Manual injection with cooling tower duckbill septum, 88
Procedure: Changing septum nut or cooling tower and septum, 89
Procedure: Installing an insert, 90
Procedure: Check needle-to-column size, 91
Procedure: Manual injection with septum nut, 92
Procedure: Manual injection with cooling tower, 93
Retention gaps, 94
Inlet temperature, 94
CryoBlast (optional), 94
Track oven mode, 94
Temperature programming mode, 95
Cryogenic considerations, 95
Setpoint ranges, 95
Procedure: Programming temperature, 96
Procedure: Operating the cool on-column inlet, 97
Part 2. Maintaining a Cool On-Column Inlet
Cool on-column inlet hardware problems, 100
Procedure: Replacing the fused silica syringe needle, 101
Procedure: Installing a fused silica needle, 102
Changing septa, 103
Procedure: Cleaning the inlet, 106
Procedure: Leak checking the gas plumbing, 109
Procedure: Leak checking a cool on-column inlet, 110
Procedure: Correcting leaks, 113
The Cool On-Column Inlet
Chapter 4.
The Cool On-Column Inlet
Part 1.
Using a Cool On-Column Inlet
This inlet introduces liquid sample directly onto a capillary column. To
do this, both the inlet and the oven must be cool at injection, at or below
the boiling point of the solvent. Because the sample does not vaporize
immediately in the inlet, problems with sample discrimination and
sample alteration are minimized. If done properly, cool-on column
injection also provides accurate and precise results.
You can operate the inlet in track oven mode, where the inlet
temperature follows the column oven, or you can program up to three
temperature ramps. There is also a cryogenic cooling option that uses
liquid CO2 or N2 to reach subambient temperatures.
This inlet is only available with electronic pneumatics control. Figure 15
shows the inlet pneumatics.
Figure 15.
Flow
limiting
frit
Cool On-Column Capillary Inlet with EPC
Proportional
valve
Pressure
sensor
PS
Inlet pressure
control loop
84
Septum holder
Septum purge
regulator (not
adjustable)
SPR
Purge vent
To detector
Cool on-column operation
Hardware
Because you are injecting sample directly into the column, most of the
hardware required is determined by your column inside diameter.
Injection technique, manual or automatic, must also be considered.
Table 11 is a checklist for choosing hardware and shows where to find
instructions for installing the hardware and injecting the sample.
Table 11.
Hardware and Procedures Checklist
Automatic Injection
Manual Injection
with Septum Nut
Manual Injection with
Cooling Tower
See Table 12 for part
numbers
See Table 12 for part
numbers
See Table 13 for part
numbers
P Septum nut
P Septum nut
P Cooling tower
P Insert
P Solid septum
P Duckbill septum
P Stainless steel needle
P Insert
P Insert
P Stainless steel needle
P Fused silica needle
(columns 200 m)
Hardware
|
or
P Stainless steel needle
(columns 250 m)
|
Where to find instructions
P Installing an Insert,
P Installing an Insert,
P Installing an Insert,
P Changing the septum
P Changing the septum
P Changing the septum
page 90
nut or cooling tower
assembly, page 89
page 90
nut or cooling tower
assembly, page 89
P Checking the needle-to- P Manual Injection techcolumn size, page 91
P Automatic Sampler
Operating Manual, HP
part no. G1513-90100
nique with septum nut
and stainless steel
needle, page 92
page 90
nut or cooling tower
assembly, page 89
P Manual injection
technique with cooling
tower, page 93 and
Replacing the fused
silica syringe needle,
page 101
85
Cool on-column operation
Figure 16.
Hardware for the Cool On-Column Inlet
2
1
3. Septum
3
4
5. Duckbill septum
6. Spring
7. Insert
Septum nut and septum, manual or automatic injection
1. Septum nut (HP part no. 19245-80521) for use with 250-m and 320-m
columns.
See Sampler manual for needle support assembly requirements.
2. Septum nut (HP part no. 19245-20670) for use with 530-m columns
3. Septum
Cooling tower and duckbill septum, manual injection
4. Cooling tower assembly (HP part no. 19320-80625)
5. Duckbill septum (HP part no. 19245-40050) for use with columns 200 m and
larger
For all applications:
6. Spring. Keeps insert in position.
7.
Insert. Guides the needle smoothly into the column. Choose based on
column and needle.
86
Cool on-column operation
Automatic or manual injection with septum nut
Choose a needle, septum nut, and insert based on your column inside
diameter. Use Table 12 to select hardware for your injection. See
Table 13 if you are doing manual injections with a duckbill septum.
Table 12.
Needle
Automatic or Manual Injection with a Stainless Steel
Column Type
and Inside Diameter
Fused silica:
530 m id
320 m id
Needle
HP part no.:*
Septum nut
HP part no.:
Insert
HP part no.:
5182-0832**
19245-20670
19245-20580
5182-0831
19245-80521
19245-20525
(five rings)
250 m id
5182-0833
19245-80521
19245-20515
(six rings)
200 m id
Aluminum-clad,
530 m id
Use cooling tower and duckbill septum
5182-0832
19245-20670
19245-20780
(four rings)
Glass capillary
320 m id
250 m id
*
**
5182-0831
5182-0833
19245-20670
19245-20550
(three rings)
Order removable needle syringe, HP part no. 5181-0836. If doing a manual injection, you must
also order a plunger button, HP part no. 5181-8866.
Many other needles can be used to inject onto a 530-m column. Consult the Hewlett-Packard Anal
í\WLFDO Columns and Supplies catalog for details.
87
Cool on-column operation
Manual injection with a cooling tower and duckbill
septum
If you are doing this type of manual injection, use either fused silica or
metal removable stainless steel needles. Use Table 13 to choose the
correct insert and syringe.
Table 13.
Septum
Manual Injection Hardware—Cooling Tower & Duckbill
Column Type and Inside Diameter
Insert (HP part no.)
Fused silica
530 m
19245-20580
(no rings)
320 m
19245-20525
(five rings)
250 m
19245-20515
(six rings)
200 m (fused silica needle only)
19245-20510
(one ring)
Aluminum-clad, 530 m
19245-20780
(four rings)
Glass capillary
19245-20550
(three rings)
Syringe and needle
Fused silica needle syringe (HP part no. 9301-0658)
Replacement needles (HP part no. 19091-63000)
or
Metal removable needle syringe (HP part no. 9301-0562)
Replacement needles (HP part no. 9301-0561)
88
Cool on-column operation
Procedure: Changing the septum nut or cooling tower and
septum
If you need to change the insert, refer also to the next section, “Installing
the Insert.”
1. Press [Oven] and set the oven to 35EC. When the temperature
reaches setpoint, turn the oven off. Press [Front Inlet] or [Back Inlet]
and turn off the inlet temperature and pressure.
WARNING
Be careful! The inlet fittings may be hot enough to cause burns.
2. Locate the septum nut or cooling tower assembly at the top of the
inlet and remove (see Figure 16). If you are using a cooling tower,
grasp the three rings and unscrew. If you are using a septum nut,
grasp the knurling and unscrew.
There should be a small spring at the inlet base. If the spring is stuck
to the septum nut, place it back in the inlet base.
3. If you are using a septum nut, remove the old septum with tweezers,
hemostat, or septum remover. Use tweezers to install a new septum.
Push the septum into the septum nut until properly seated.
If you are using a cooling tower assembly, locate the duckbill septum
and install in the inlet base so that the duckbill is inserted inside the
coil spring.
4. Install the septum nut or cooling tower assembly and tighten firmly.
5. Before making an injection, check the alignment of the entire
assembly.
89
Cool on-column operation
Procedure: Installing an insert
1. Choose an insert. See Table 12 or Table 13 for instructions on
choosing an insert.
2. Press [Oven] and set the oven to 35EC. When the temperature
reaches setpoint, turn the oven off. Press [Front Inlet] or [Back Inlet]
and turn off the inlet temperature and pressure.
3. Remove the column, column nut, and ferrule.
4. Locate the septum nut or cooling tower assembly at the top of the
inlet and remove it.
If the septum remains in the septum nut, do not remove it unless you
want to change it. If necessary, replace the existing septum or
duckbill with a new one. See the Maintenance part of this chapter for
detailed instructions. Set the inlet septum nut or cooling tower
assembly aside.
5. Remove the spring from the inlet with an extraction wire, and set it
aside. Be careful not to lose or damage it because you will use the
spring to keep the new insert in position.
6. Remove the existing insert from the inlet by gently pushing it out
from below with a wire or piece of column. Store the insert for
possible later use.
7. Drop the new insert straight into the inlet from the top.
8. Replace the spring on top of the insert.
9. Reinstall the septum nut or duckbill septum and cooling tower
assembly and tighten finger tight.
10. Reinstall the column, nut, and ferrule.
90
Cool on-column operation
Procedure: Check the needle-to-column size
Caution
This applies to 250 ³ and 320 ³ columns only.
After selecting an insert and before installing a column, you need to
check the needle-to-column size to make certain your needle fits in the
column. You could bend the needle if you try to inject it into a smaller
column. Use the insert that is the same size as your syringe needle to
verify that the column you plan to use is the correct size.
1. Identify the correct insert.
2. Insert the column into one end of the insert as shown below.
Syringe
Insert
Column
3. Insert the syringe needle through the other end of the insert and into
the column. If the needle cannot pass easily into the column, reverse
the insert to try the needle and column in the other end.
If the needle still cannot pass into the column, you may have a column
with an incorrect id. Check the column to make sure it is labeled
correctly, and try a new column.
91
Cool on-column operation
Procedure: Manual injection with septum nut
Before making your injection, make sure the correct septum nut and
septum are installed.
1. Immerse the syringe needle in sample; pump the syringe plunger to
expel air from the barrel and needle.
2. Draw the sample into the syringe.
3. Remove the needle from the sample and draw about 1 ³L of air into
the syringe.
4. Wipe the needle dry if it is wet.
5. Guide the needle straight into the septum nut, pierce the septum,
and insert the needle fully into the inlet until it bottoms.
6. Start the run, depress the syringe plunger as quickly as possible, and
withdraw the needle from the inlet.
These steps should be done smoothly, with minimal delay.
92
Cool on-column operation
Procedure: Manual injection with cooling tower
When injecting with fused silica or metal removable stainless steel
needles, be sure the cooling tower assembly and duckbill are installed on
the inlet. Initial pressure must be set at less than 30 psi. Higher
pressures will make needle insertion difficult.
1. Immerse the syringe needle in the sample and pump the syringe
plunger to expel air from the barrel and needle.
2. Draw the sample into the syringe. Allow enough time for fluids to
pass through the small bore of the needle.
3. Remove the needle from the sample and draw about 1 ³l of air into
the syringe. Wipe the needle with a tissue wetted with solvent.
4. Press down the top of the cooling tower with a pencil to open the
duckbill.
WARNING
The cooling tower may be hot!
5. Hold down the cooling tower and guide the needle until it is fully
inserted in the inlet. You may observe a drop in the pressure reading
on the control table.
If the needle does not go in all the way, try rotating the syringe and
slightly releasing pressure on the cooling tower.
If you still cannot get the needle in, the duckbill opening may be
stuck. Try removing the duckbill, opening it manually, and
reinstalling it.
6. Once the needle has entered the column, release the cooling tower
and continue to insert the needle. Allow 1 to 2 seconds for back
pressure on the duckbill to seal it around the inserted needle.
7. Start the GC, depress the syringe plunger as quickly as possible, and
withdraw the needle from the inlet.
93
Cool on-column operation
Retention gaps
Because the sample is injected directly onto the column, it is strongly
suggested that a retention gap—or guard column—be used to protect
your column. A retention gap is a deactivated column that is connected
between the inlet and the analytical column. If you choose to use one, it
is suggested that at least 1 m of retention gap be installed per 1 mL of
sample injected. Information on ordering retention gaps can be found in
the Hewlett-Packard Analytical Columns and Supplies Catalog.
If you are using a retention gap and are operating with column defined,
the length of the retention gap could affect the calculations for flow and
velocity through your column. If your retention gap is the same inside
diameter as your column, it is a good idea to add the retention gap and
column length before entering the number on the Configure Column
control table. If the retention gap inside diameter is larger than your
column, this step may not be necessary.
Inlet temperature
CryoBlast (optional)
CryoBlast shortens the cycle time between runs. If you have a CO2 or N2
cryogenic valve and the cryoblast feature, you can cool the inlet to 37EC
in either the track oven or temperature program modes.
Track oven mode
In the Track oven mode, the inlet temperature stays 3EC higher than the
oven temperature throughout the oven program. You cannot enter a
temperature setpoint—it is set automatically. If you have CryoBlast, the
inlet will track oven temperatures to 40EC; without CryoBlast, the
lower limit is set by room temperature.
94
Cool on-column operation
Temperature programming mode
In this mode, you can enter up to three temperature ramps in the inlet
control table so that the inlet and the oven operate independently. This
is the recommended mode if operating below 20C.
At these very low oven temperatures, the inlet temperature should be at
least 20C higher than the oven temperature. This will be more than
adequate for solvent focusing.
At temperatures greater than ambient, the inlet should always be at
least 3C warmer than the oven for proper control of the inlet
temperature.
The oven temperature program controls the run. If it is longer than the
inlet temperature program, the inlet will remain at its final temperature
until the oven program (and the run) ends.
Cryogenic considerations
When using track oven mode with a cryogenic oven, all other inlets must
be off or in track oven mode.
Setpoint ranges
The table below lists setpoint ranges for the inlet parameters.
Temperature
Allowed setpoint range
Track oven
3EC higher than the oven temperature to a
maximum of 450EC. If you have cryoblast, the
inlet can maintain temperatures down to
íEC, although allowable oven setpoints are
60EC for CO2 and íEC for N2
Ramped temp without cryoblast
24EC to 450EC
Ramped temp with cryoblast
40EC to 450EC
95
Cool on-column operation
Procedure: Programming the temperature
1. Press [Front Inlet] or [Back Inlet].
2. Press [Mode/Type] and select Ramped temp.
Ramped temp mode
Press [Mode/Type]
FRONT INLET (COC)
Mode:
Ramped temp <
Temp
100
100
Init time
1.00
Rate 1
4.00
Final temp 1
200
Final time 1
35.00
Rate 2 (off)
0.00
Pressure
10.0
10.0
FRONT INLET MODE
Track oven
*Ramped temp
<
3. Enter a Temperature. This is the starting temperature.
4. Enter an Init time. This is the length of time the inlet will stay at the
starting temperature after a run has begun.
5. Enter a Rate. This is the rate at which the inlet will be heated or
cooled. A Rate of 0 halts further programming.
6. Enter the Final temp. This is the inlet temperature at the end of the
first ramp.
7. Enter the Final time. This is the number of minutes the inlet holds
the Final temp.
8. To enter a second (or third) ramp, scroll to the appropriate Rate line
and repeat steps 5 through 7.
96
Cool on-column operation
Procedure: Operating the cool on-column inlet
Verify that a column and suitable insert and septum nut or cooling tower
are installed. Make certain you are using a needle that will fit the
column.
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
Pressure can be set from either the column or inlet table. In constant
or ramped flow mode, the pressure will be determined from the flow
requirements. It is best to set flow only.
Track oven mode
FRONT INLET (COC)
Mode:
Track oven
Temp
24
Off
Pressure
10.0
10.0
Ramped temp mode
FRONT INLET (COC)
Mode:
Ramped temp
Temp
100
100
Init time
1.00
Rate 1
4.00
Final temp 1
200
Final time 1
35.00
Rate 2 (off)
0.00
Pressure
10.0
10.0
2. Press [Front Inlet] or [Back Inlet]
a. Choose a temperature mode: Track oven or Ramped temp.
b. For Ramped temp mode, enter your temperature ramps (page
96). There is no setpoint for Track oven mode.
3. Inject a sample.
97
Cool on-column maintenance
Part 2.
Maintaining a Cool On-Column Inlet
Maintaining the cool on-column inlet includes changing septa, cleaning
inlet components, and checking and correcting leaks in the system.
The cool on-column inlet’s hardware will vary depending on whether you
will be making manual or automated injections, the type of needle you
use, and the size of column you use.
Figure 17.
Systems
The Cool On-Column Inlet for Automatic Injection
Septum nut
(250- and 320-m columns)
Septum
Septum nut
(530-m columns)
Septum
Spring
Insert (varies according
to column used)
98
Cool on-column maintenance
Figure 18.
The Cool On-Column Inlet for Manual Injection Systems
Cooling tower assembly
HP part no.
19320-80625
Duckbill septum
HP part no. 19245-40050
Spring
Insert (varies according
to column used)
99
Cool on-column maintenance
Cool on-column inlet hardware problems
The inlet cools very slowly
- The inlet fan is not running or is blowing away from the inlet. Check
the fan to make sure it is operating. If it is not, contact your
Hewlett-Packard service representative.
The inlet is unable to reach a temperature setpoint
- Check the temperature equilibration time. If the equilibration time is
too short, the inlet may oscillate. Increase the equilibration time.
- Check that the cryogenic cooling is turned off. If you do not turn off
cryogenic cooling when it is not in use, both the inlet and the oven
may be unable to reach a temperature setpoint, particularly
temperatures near room temperature. If you turn the cryogenic
cooling off and the inlet still fails to reach the setpoint temperature,
contact your Hewlett-Packard service representative.
The syringe needle bends during injections
- The needle may have been defective before the injection was made.
Check each syringe before injection to make sure the needle is
straight.
- Check that the needle support assembly is installed correctly
- Check that the correct insert is installed and that it is installed
correctly
- Check the alignment of the inlet septum and the septum nut.
- The inlet septum hole may have closed. Replace the septum.
If you are using the GC Automatic Liquid Sampler (GC ALS):
See the GC ALS manual for additional information.
- The sampler vials may be over-crimped.
- Check the needle guide for signs of wear or damage. Replace the
needle guide if necessary.
- Check the alignment of the inlet and the automatic sampler.
100
Cool on-column maintenance
Procedure: Replacing the fused silica syringe needle
1. Hold the syringe vertically and insert the fused silica needle so it is
visible inside the syringe barrel. If the fused silica needle cannot be
inserted into the syringe barrel, the Teflon ferrule (HP part no.
0100-1389) may be blocked. You may need to replace the ferrule.
Push the plunger down until it bottoms. The needle will now be flush
with the end of the plunger.
2. When the needle is inserted, tighten the retaining nut to firm finger
tightness. Pull the needle gently to be sure the Teflon ferrule has
formed a tight seal with the needle. Tighten the retaining nut
further, if necessary.
3. Loosen the retaining nut just enough so the needle is again free.
Depress the syringe plunger slowly until it pushes the needle to the
end of the barrel, then tighten the retaining nut to firm finger
tightness.
4. Use a solvent to rinse the syringe and check for leaks or blocks.
5. Leaks (inability to eliminate air bubbles) may be fixed by further
tightening the retaining nut. Blocks (or serious leaks) require
repeating this procedure.
The Teflon ferrule may lose its seal in time. If so, first retighten the
retaining nut and, if the seal still leaks, install a new Teflon ferrule and
needle.
When not in use, loosen the retaining nut to avoid premature leaks.
101
Cool on-column maintenance
Procedure: Installing a fused silica needle
Fused silica
needle
Ferrule
sleeve
Teflon
ferrule
If you are cutting replacement needles directly from fused silica column
material:
1. Column material for making needles must have an outside diameter
smaller than both the inside diameter of the on-column inlet (0.23
mm) and the inside diameter of the installed column.
2. Column material must be washed free of active stationary phase.
3. Score the column material about 1/4 inch from its end. Break off the
end and discard. Then measure, score, and break off a 115 + 5 mm
length to use as the syringe needle.
102
Cool on-column maintenance
Changing septa
If the septum leaks, you will see symptoms such as longer or shifting
retention times, loss of response, and/or loss of column head pressure.
Additionally, the detector signal will become increasingly noisy.
The useful lifetime of septa is determined by injection frequency and
needle quality; burrs, sharp edges, rough surfaces, or a blunt end on the
needle decrease septum lifetime. When the instrument is used regularly,
daily septum replacement is recommended.
The type of septa you use will depend on your chromatography needs.
You can order septa directly from Hewlett-Packard; see the Analytical
Columns and Supplies Catalog for ordering information.
Caution
The procedure for changing septa differs depending on whether you cool
on-column inlet has a cooling tower assembly or a septum nut. Make
sure to follow the correct procedure for your inlet!
Table 14.
Recommended Septa for the Cool On-Column Inlet
Description
HP Part Number
Solid septum for manual and automatic
injection
5181-1261
Duckbill septum for manual injection only
(must use cooling tower with the duckbill)
19245-40050
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
Caution
Column flow is interrupted while changing septa; since columns may be
damaged at elevated temperatures without carrier flow, cool the oven to
room temperature before proceeding.
103
Cool on-column maintenance
Procedure: Changing septa
Materials needed:
- New septum—see Table 14 on page 103 for part numbers
- Forceps (or tweezers)
- A thin wire (0.2-in. diameter) for removing septum from inlet
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Cool the oven to room temperature and then turn the oven off.
- Cool the inlet to room temperature and then turn the inlet off.
Depending on your analysis and injection technique, the inlet will have
one of the following septum nuts or a cooling tower assembly.
Septum nut for injections onto
250- and 320-m columns
Septum nut for injections
onto 530-m columns
Cooling tower assembly
(for manual injections
only)
104
Cool on-column maintenance
2. If you have a cooling tower assembly installed:
Remove the assembly by grasping it and turning counterclockwise. The
duckbill septum is underneath the cooling tower inside the spring. The
spring and septum may pop out of the inlet when you remove the cooling
tower. Be careful not to lose them. If they do not pop out, use a thin wire
to remove them from the inlet.
Cooling tower assembly
Spring
Duckbill
septum
Insert the duckbill septum into the spring and place them in the inlet.
Reattach the cooling tower assembly. Tighten it finger-tight.
2. If you have a septum nut installed:
Remove the septum nut by grasping the knurling and turning counterclockwise. The septum is probably attached to the septum nut. The
spring may also pop out when you remove the septum nut. Be careful
not to lose it. If the septum is not attached, you may need to use
tweezers to grasp and remove it.
Septum nut
(250- and 320-m
columns)
Septum
Septum nut
(530-m columns)
Septum
Spring
Spring
Make sure the spring is in the inlet. Use the tweezers to place a new
septum on the bottom of the septum nut, and then reattach the septum nut
to the inlet. Tighten the nut firmly.
3. Restore normal GC operating conditions.
105
Cool on-column maintenance
Procedure: Cleaning the inlet
Most laboratories have airborne lint and dust that accumulate on the
cooling tower or septum nut and can enter the inlet or column on the
syringe needle. Particulate matter in the inlet interferes with easy
passage of the syringe needle. If dirt enters the column, it can alter the
chromatography.
You can clean the needle guides, springs and inserts according to the
following procedure.
WARNING
Be careful! The oven and/or inlet may be hot enough to cause burns.
Materials needed:
- 9/16-in. wrench
- Narrow wire (0.02-in. diameter) or piece of capillary column (250-³
-
106
diameter) for removing spring and insert
Small ultrasonic cleaning bath with aqueous detergent
Distilled water
Methanol
Compressed, filtered, dry air or nitrogen
Cool on-column maintenance
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Allow the oven and inlet to cool.
- Turn off all flows to the inlet at the initial gas supply.
- Turn off the GC and unplug it.
- Remove the column. See the “Columns and Traps” chapter in the
General Information volume.
2. If you have a cooling tower assembly installed:
Remove the assembly by grasping it and turning counterclockwise.
The septum is underneath the cooling tower inside the spring. The
spring and septum may pop out of the inlet when you remove the
cooling tower. Be careful not to lose them. If they do not pop out, use
a thin wire to remove them from the inlet.
Cooling tower assembly
Spring
Duckbill
septum
2. If you have a septum nut installed:
Remove the septum nut by grasping the knurling and turning
counterclockwise. The septum is probably attached to the septum nut. The
spring may also pop out when you remove the septum nut. Be careful
not to lose it.
Septum nut
(250- and 320-m
columns)
Septum
Septum nut
(530-m
columns)
Septum
Spring
Spring
107
Cool on-column maintenance
3. Insert the narrow wire (or a piece of capillary column) into the inlet
through the oven, and push the insert and spring (if they did not
come out previously) out through the top of the inlet.
Spring
Insert (varies
according to column
use)
Insert wire into inlet from oven
4. Cleaning procedure:
a. Fill the ultrasonic cleaning bath with aqueous detergent, and place
the spring and the insert into it. Sonicate for one minute.
b. Drain the aqueous detergent, and fill the bath with distilled water.
Sonicate for one minute.
c. Remove the parts from the bath, and rinse them thoroughly with
water and methanol.
d. Dry the parts with a burst of compressed air or nitrogen.
5. Reinstall the insert. If you are using a septum nut, insert the spring
and insert, with the spring on top.
6. Attach a new septum to the bottom of the septum nut. If you are using
the cooling tower assembly, insert a new duckbill septum into the
spring, and place them in the inlet.
7. Attach the septum nut or the cooling tower and tighten finger-tight.
Reinstall the column, and then restore normal operation conditions.
108
Cool on-column maintenance
Procedure: Leak testing the gas plumbing
Leaks in the gas plumbing system can affect chromatographic results
dramatically. The following procedure checks the flow system up to but
not including the inlet flow manifold. If this portion of the system proves
to be leak-free, refer to the next procedure to leak-check the inlet and
inlet manifold.
Liquid leak detectors are not recommended, especially in areas where
cleanliness is very important.
If you do use leak detection fluid, immediately rinse the fluid off to
remove the soapy film.
WARNING
To avoid a potential shock hazard when using liquid detection fluid, turn
the GC off and disconnect the main power cord. Be careful not to spill
leak solution on electrical leads, especially the detector heater leads.
Materials needed:
- Electronic leak detector capable of detecting your gas type or liquid
-
leak detection fluid. If you use leak detection fluid, remove excess
fluid when you have completed the test.
Two 7/16-in. wrenches
1. Using the leak detector, check each connection you have made for leaks.
2. Correct leaks by tightening the connections. Retest the connections;
continue tightening until all connections are leak-free.
109
Cool on-column maintenance
Procedure: Leak testing a cool on-column inlet
There are numerous places in the inlet that can leak. This procedure lets
you determine, in general, if there is an unacceptable leak in the inlet.
If the inlet is leaking, you should use an electronic leak detector to
pinpoint the component that is leaking.
Materials needed:
- No-hole ferrule
- 1/4-in. wrench
- Gloves (if the inlet is hot)
1. Complete the following preliminary steps:
- If you have entered parameters that you do not want to lose, store
them as a method.
- Allow the oven to cool to room temperature and then turn it off.
- When the oven is cool, turn off the inlet pressure.
- Remove the column, if one is installed, and plug the column fitting
with the column nut with a no-hole ferrule installed.
- Remove the old septum and replace it with a new one. For instructions,
see page 104.
2. Set the oven temperature to its normal operating temperature.
Press
[Oven]
OVEN
Temp
Init time
Rate 1 (off)
110
250
250 <
0.00
0.00
Cool on-column maintenance
3. Set inlet to normal operating temperature. Enter a pressure between 20
and 25 psi, or enter your normal operating pressure, if it is higher. Make
sure that the pressure at the initial gas supply is at least 10 psi higher
than the inlet pressure.
Press [Front Inlet] or
[Back Inlet]
FRONT INLET (coc)
Mode:
Track oven
Temp
150 150 <
Pressure
24.0 24.0
Total flow
0.0
OR
FRONT INLET (coc)
Mode:
Ramped temp
Temp
150 150 <
Init time
0.00
Rate 1 (Off)
0.00
Pressure
24.0 On
4. Wait a few minutes for the GC to equilibrate after the system has
reached the pressure. (The rest of the examples of the Front Inlet control
table will show the table that appears if the inlet is in track mode.)
Press [Front Inlet]
or [Back Inlet]
The GC may exceed
the pressure setpoint
slightly while
equilibrating.
FRONT INLET (coc)
Mode:
Track oven
Temp
150 150
Pressure
24.2 24.0<
111
Cool on-column maintenance
5. Turn the pressure off. Because the column is capped, the pressure
should remain fairly constant.
Press [Front
Inlet] or [Back
Inlet]
FRONT INLET (coc)
Mode:
Track oven
Temp
150 150
Pressure
24.2 Off<
Because the pneumatics have been turned off, the alarm does not sound
even though there is no flow through the column.
6. Continue to monitor pressure for 10 to 15 minutes. You can use the GC’s
Stopwatch function. A pressure drop of 0.03 psi/min or less is acceptable.
Press [Time]
9:56:08
12 Dec 94
Last runtime
Next runtime
t = 0:04.9
1/t = 12.24
0.00
999.99
If the pressure drop is 0.03 psi/min or less, you can consider the inlet
system leak-free.
If the pressure drops faster than the acceptable rate, go to the next section,
“Correcting Leaks.”
112
Cool on-column maintenance
Procedure: Correcting leaks
Materials needed:
- Electronic leak detector
- 1/4-in. wrench
1. Use the electronic leak detector to check all areas of the inlet that are
potential sources of a leak. Potential leak areas are:
- The plugged column connection
- The septum nut, if present
- The cooling tower assembly, if present
2. Correct leaks, using the wrench if necessary, to tighten connections. You
may need to repeat the leak test again to check for leaks.
If the pressure drop is now 0.03 psi/min or less, you can consider the inlet
system leak-free.
If the pressure drops faster than the acceptable rate, continue to search for
leaks and repeat the pressure test. If all fittings appear to be leak free, but
the inlet system is still losing too much pressure, you may need to replace
the inlet manifold. Contact your Hewlett-Packard service representative.
113
5
Part 1. Introducing the HP PTV
Operating modes and system requirements, 116
System components, 117
Heating and cooling the inlet, 119
Part 2. Using the Split Modes
Procedure:
Procedure:
Procedure:
Procedure:
Split mode, column defined, 126
Split mode, column not defined, 127
Pulsed split mode, column defined, 130
Pulsed split mode, column not defined, 131
Part 3. Using the Splitless Modes
Procedure:
Procedure:
Procedure:
Procedure:
Splitless mode, column defined, 138
Splitless mode, column not defined, 139
Pulsed splitless mode, column defined, 141
Pulsed splitless mode, column not defined, 142
Part 4. Using the Solvent Vent Mode
Sequence of operations and timelines, 146
When is Start Run?, 148
Procedure: Solvent vent mode, column defined, 151
Procedure: Solvent vent mode, column not defined, 152
Large volume injection, 153
Part 5. Maintaining a PTV
Inlet adapters, 161
Procedure: Installing columns, 162
The septumless head, 164
The septum head, 168
Glass inlet liners, 171
The Programmable Temperature Vaporization Inlet
Chapter 5.
The Programmable Temperature
Vaporization Inlet
Part 1.
Introducing the HP PTV
Operating modes
The Hewlett-Packard Programmed Temperature Vaporization (PTV)
Inlet System has five operating modes:
- The split mode is generally used for major component analyses.
- The pulsed split mode is like the split mode, but with a pressure
pulse applied to the inlet during sample introduction to speed the
transfer of material to the column.
- The splitless mode is used for trace analyses.
- The pulsed splitless mode allows for a pressure pulse during sample
introduction.
- The solvent vent mode is used for large volume injection. Either
single or multiple injections can be made for each run.
System requirements
The PTV inlet can be used with both manual and automatic injection.
If an HP automatic sampler is used, it must be a model G1513A
autosampler (firmware G1513A.09.14 or later) with a G1512A controller
(firmware G1512A.01.08 or later)
For automatic multiple injections (large volume injections), an HP GC or
MSD ChemStation is required. This function is not available under HP
6890 control alone. See part 4 of this chapter.
116
PTV introduction
System components
1. The pneumatics module, located at the top rear of the GC.
2. The inlet body, always mounted in the front inlet position.
3. The trap, which is in the split line and placed to the left of the
pneumatics carrier at the top rear of the chromatograph.
4. The coolant control valve. For liquid nitrogen, this valve is on the left
outside wall of the oven. For liquid carbon dioxide, it is in the
pneumatics carrier. These valves are not interchangeable—if you
change coolants, you must also change all of the coolant plumbing
including the valve and inlet jacket.
5. The thermocouple conversion board. It converts thermocouple
readings from the inlet for use by the GC and is near the trap.
Figure 19.
PTV system components
Split
vent
Septum purge vent
PV2
SPR
Sol
PS
Trap
Carrier
supply
PV
SPR
tor
Sol
PS
FS
CCV
valve
PV1
FS
Pneumatics module
Proportional valve
Septum purge regulaSolenoid valve
Pressure sensor
Flow sensor
Cryogenic coolant
CCV
Inlet
Coolant
supply
Alternate purge flow paths
With septum head
With septumless
head
117
PTV introduction
Sampling heads
Two heads are available for the PTV inlet.
- The septum head uses either a regular septum or a Merlin
microseal to seal the syringe passage. A stream of gas sweeps the
inner side of the septum and exits through the septum purge vent on
the pneumatics module. It may be used with either automatic or
manual injection.
Caution
At inlet temperatures below 40C, the Merlin microseal may not seal
effectively—use a regular septum instead.
- The septumless head uses a check valve instead of a septum to seal
the syringe entrance passage. It may be used with either automatic
or manual injection.
Figure 20.
Sampling heads
Septum head
Septumless head
Carrier gas and septum
purge
lines to pneumatics module
Note:
Two gas lines (carrier
supply and septum
purge), meeting at the
pneumatics module.
Uses either standard 11
mm septa or (with a different cap) a Merlin microseal.
Carrier gas line
Note:
One gas line (carrier
supply).
No septum, so no septum purge line. Septum
purge stream exits
through bypass line.
The flow diagrams in the rest of this book show the septum head in place
with a separate drawing for the septumless head plumbing.
118
PTV introduction
Heating the inlet
The control parameters for PTV temperature programming are the same
as for the column oven, but are reached by pressing [Front Inlet].
Temperature can be programmed with an initial temperature and up to
3 rates and plateaus. Rates between 0.1 and 720C/min can be selected.
See chapter 4 of the General Information volume for details.
Caution
If the initial inlet temperature and the oven initial temperature are too
close, the inlet may be unable to maintain its setpoint. We recommend a
difference of at least 6C, either higher or lower.
Additional temperature ramps
For most purposes, the PTV is designed to hold the sample in the inlet
liner until the entire sample—there could be several injections—has
been injected. Then the PTV is heated rapidly to transfer the sample to
the column. This can be accomplished with an initial hold, a single ramp,
and a hold at the end to complete sample transfer.
Two additional ramps are available and have several possible uses:
- The inlet can be heated to a high temperature to thermally clean the
liner for the next run.
- The inlet can be programmed downward—just set the Final temp
below the previous temperature—to reduce thermal stress on the
inlet.
- Downward programming can be used to prepare the inlet for the next
run. This can reduce cycle time for greater sample throughput.
119
PTV introduction
Cooling the inlet
The sample may be injected into either a cooled or heated chamber. The
initial chamber temperature can be reduced to 60C (with CO2 cooling)
or to 160C (with liquid N2 cooling).
Caution
If the initial inlet temperature and the oven initial temperature are too
close, the inlet may be unable to maintain its setpoint. We recommend a
difference of at least 6C, either higher or lower.
The HP 6890 GC supports only one type of coolant at a time.
Once a coolant is selected for any cryogenic device, that same
coolant must be used for all such devices, including the column
oven.
Since the GC can sense which coolant is used by the oven, if
oven cooling is installed that coolant becomes the one that
must be used by all other cooling devices.
Configuring the PTV
To configure the PTV, press [Config] [Front Inlet]. If the inlet has not
been configured previously, this screen is displayed.
1. Press [Config][Front Inlet]
CONFIG FRONT INLET
Gas type
He
Cryo type
None <
2. Scroll to coolant type
3. Press [Mode/Type]
INLET CRYO TYPE
*None
N2 cryo
CO2 cryo
<
4. Scroll to coolant used, press [Enter]
If oven cooling is installed, your choices are restricted to the coolant used
by the oven or None. If oven cooling is not installed, you must specify the
coolant using the procedure in the figure.
120
PTV introduction
If the Cryo type selection is anything other than None, several other
parameters appear.
CONFIG FRONT INLET
Gas type
He
Cryo type
N2
Cryo
Off
Use cryo temp
25
Cryo timeout
30
Cryo fault
On
Cryo [ON] enables cryogenic cooling of the inlet as soon as the column
oven reaches its initial temperature. [OFF] disables cooling.
Use cryo temp If Cryo is ON, this is the upper limit of temperatures at
which cryo cooling is used to hold the inlet at its setpoint. If the setpoint
is higher than this limit, cryogenic cooling is used to bring the inlet down
to its setpoint but is not used to hold it at the setpoint.
Cryo timeout Cryo timeout occurs, and the inlet temperature shuts
down, when a run does not start within a specified time (range 5 to 120
minutes, default 30 minutes) after the oven equilibrates. Turning cryo
timeout off disables this feature. We recommend that it be turned on
because cryo timeout conserves coolant at the end of a sequence or if
automation fails. A Post Sequence method could also be used.
Cryo fault Shuts down the inlet temperature if it does not reach setpoint
in 16 minutes of continuous cryo operation. Note that this is the time to
reach the setpoint, not the time to stabilize and become ready at the
setpoint.
121
PTV introduction
Shutdown behavior
Both Cryo timeout and Cryo fault can cause cryo shutdown. If this
happens, the inlet heater is turned off and the cryo valve closes. The GC
beeps and displays this message:
SHUTDOWN (#18):
Front inlet cryo
shutdown
The inlet heater is monitored to avoid overheating. If the heater remains
on at full power for more than 2 minutes, the heater is shut down. The
GC beeps and displays this message:
SHUTDOWN (#22):
Front inlet heating
too slowly;
temperature shut off
To recover from either condition, turn the GC off, then on, or enter a new
setpoint.
122
PTV split mode operation
Part 2.
Using the Split Modes
Flow pattern
The two split modes—with or without a pressure pulse—divide the gas
stream entering the inlet between the column flow, the split vent flow
through the solenoid valve, and the septum purge flow. The ratio of the
split vent flow to the column flow is called the split ratio.
The main figure shows the flows with the septum head. Flows with the
septumless head are the same except that the septum purge flow
bypasses the head (lower left).
Flow
limiting
frit
Total flow
control loop
Pressure
sensor
Septum purge
regulator
PS
SPR
Septum
head
Column head pressure control loop
FS
Proportional
valve 1
Flow
sensor
Septum
purge
vent
Split
vent
Trap
Solenoid
valve
open
Proportional
valve 2
Glass liner
Flows with septumless
head
PS
To detector
FS
Septumless
head
123
PTV split mode operation
Temperature considerations
Cold split introduction
For cold split sample introduction, use an initial inlet temperature below
the normal boiling point of the solvent. If the liner volume is enough to
hold all the vaporized solvent, start the first inlet temperature ramp at
0.1 minutes with a high heating rate (500C/min or higher). The final
temperature should be high enough to volatilize the heaviest analytes
from the liner and should be held for at least 5 minutes. A final
temperature of 350C for 5 minutes has proven sufficient to
quantitatively transfer C44.
For larger injection volumes or to eliminate the solvent, hold the initial
temperature long enough to vent the solvent through the Split vent and
then begin the first ramp. Use a fast rate for thermally stable analytes.
Slower rates may help minimize thermal degradation in the inlet.
A single temperature ramp is enough for the injection process. The
remaining ramps may be used to clean the liner or to reduce the inlet
temperature in preparation for the next injection.
Hot split introduction
For hot split introduction, set an initial temperature high enough to
volatilize the analytes. No additional thermal parameters are required
as the inlet will maintain the setpoint throughout the run.
Because of the small liner volume (about 120 microliters), the PTV has a
limited injection capacity with hot split introduction. Injection volumes
exceeding 1 ³L in the hot split mode may overflow the inlet causing
analytical problems. Cold split introduction avoids this potential
problem.
124
PTV split mode operation
Control table parameters—split mode operation
Mode:
The current operating mode—split
Temp
Actual and setpoint inlet initial temperatures.
Hold time at the inlet initial temperature.
Init time
Rate #
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final time #
Pressure
Final inlet temperature for ramps 1, 2, and 3.
Hold time at Final temp 1, 2, and 3.
Actual and setpoint inlet pressure
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This line does not appear if
your column is not defined.
Split flow Flow, in mL/min, from the split/purge vent. This line does not
appear if your column is not defined.
Total flow These are the actual and setpoint values of the total flow into
the inlet, which is the sum of the split flow, column flow, and septum
purge flow. When you change the total flow, the split ratio and split flow
change while the column flow and pressure remain the same.
125
PTV split mode operation
Procedure: Using split mode with the column defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet]
a. Scroll to Mode: and press [Mode/Type]. Select Split.
b. Set the inlet temperature and any desired ramps.
Split ratio =
Split flow
Column flow
c. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow will be calculated and set for you.
d. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio will be calculated and displayed for you.
e. If desired, turn on Gas saver. Set the Saver time after the
injection time.
Press [Mode/Type]
FRONT INLET (HP PTV)
Mode:
Split
Temp
40
40 <
Init time
0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Split ratio
50.0
Split flow
100.0
Tot flow
104
104
Gas saver
On
Saver flow
20.0
Saver time
5.00
FRONT INLET MODE
Solvent vent
*Split
<
Splitless
Pulsed split
Pulsed splitless
Only one rate is
necessary for this
example.
Additional rates are at
the user’s discretion.
If using gas saver,
set time after injection
time.
3. Press [Prep Run] before manually injecting the sample if the Gas
Saver is on (see page 13).
126
PTV split mode operation
Procedure: Using split mode with the column not defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Set temperature.
b. Set total flow into the inlet. Measure flows out of the split vent
and septum purge vent using a flow meter.
c. Subtract the septum purge flow from Total flow to get split flow.
d. Calculate the split ratio. Adjust as needed.
Press [Mode/Type]
FRONT INLET (HP PTV)
Mode:
Split
Temp
40
40 <
Init time
0.10
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
10.0
10.0
Tot flow
80.3
80.3
FRONT INLET MODE
Solvent vent
*Split
<
Splitless
Pulsed split
Pulsed splitless
Only one rate is
necessary for this
example.
Additional rates are at
the user’s discretion.
Septum purge
Split vent
Front of instrument
127
PTV split mode operation
Pulsed modes
The pressure pulse modes (split and splitless) increase inlet pressure just
before the beginning of a run and return it to the normal value after a
specified amount of time. The pressure pulse sweeps the sample out of
the inlet and into the column faster, reducing the chance for sample
decomposition in the inlet. If your chromatography is degraded by the
pressure pulse, a retention gap may help restore peak shape.
You must press the [Prep Run] key before doing manual injections in the
pressure pulse mode.
You can do column pressure and flow programming when in the pressure
pulse mode. However, the pressure pulse will take precedence over the
column pressure or flow ramp.
Figure 21.
Pressure Pulse and Column Flow or Pressure
Pressure pulse
Actual
pressure
Pressure (or flow) program
0
128
1
2
3
4
5
Time (min)
6
7
8
PTV split mode operation
Control table parameters—pulsed split mode
Mode:
The current operating mode—pulsed split
Temp
Actual and setpoint inlet temperatures
Init time
Rate #
Hold time at the initial inlet temperature.
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final time #
Final inlet temperature for ramps 1, 2, and 3.
Hold time at Final temp 1, 2, and 3.
Pressure Actual and setpoint inlet pressure before and after the
pressure pulse. This is the starting point of a pressure program or the
fixed pressure if a program is not used.
Pulsed pres The inlet pressure you desire at the beginning of a run.
The pressure rises to this setpoint after [Prep Run] is pressed and
remains constant until Pulse time elapses, when it returns to Pressure.
Pulse time Inlet pressure returns to its normal setpoint at this time
after Start Run.
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This line does not appear if
your column is not defined.
Split flow Flow, in mL/min from the split/purge vent. This line does not
appear if your column is not defined.
Total flow The total flow into the inlet, the sum of the split flow, column
flow, and septum purge flow. When you change total flow, the split ratio
and split flow change while column flow and pressure remain the same.
When a pressure pulse is used, total flow increases to keep the split ratio
constant.
129
PTV split mode operation
Procedure: Using pulsed split mode with the column defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Split.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed Pres and Pulse time.
Split ratio =
Split flow
Column flow
d. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow is calculated and set for you.
e. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio is calculated and displayed for you.
f.
Turn Gas saver on, if desired. Set the time greater than Pulse
time.
FRONT INLET (HP PTV)
Mode: Pulsed split
Temp
40
40 <
Init time
0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Pulsed pres
30.0
Pulse time
1.0
Split ratio
50.0
Split flow
100.0
Tot flow
104
104
Gas saver
On
Saver flow
20.0
Saver time
5.00
Press [Mode/Type]
FRONT INLET MODE
Solvent vent
Split
Splitless
*Pulsed split
<
Pulsed splitless
3. Press [Prep Run] (see page 13) before injecting a sample manually.
130
PTV split mode operation
Procedure: Using pulsed split mode with the column not
defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Split.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed Pres and Pulse time.
d. Set total flow into the inlet. Measure flows out of the split vent
and septum purge vent using a flow meter.
e. Subtract the septum purge flow from Total flow.
f.
Calculate the split ratio. Adjust as needed.
FRONT INLET (HP PTV)
Mode: Pulsed split
Temp
40
40 <
Init time
0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Pulsed pres
30.0
Pulse time
1.0
Tot flow
104
104
Press [Mode/Type]
FRONT INLET MODE
Solvent vent
Split
Splitless
*Pulsed split
<
Pulsed splitless
131
PTV splitless mode operation
Part 3.
Using the Splitless Modes
Flow patterns
In these modes—with or without a pressure pulse—the solenoid valve is closed
during injection and vaporization of the sample and stays so while the sample
transfers to the column. At a specified time after injection, the valve opens to
sweep vapors left in the liner out the split vent. This avoids solvent tailing due
to the large inlet volume and small column flow rate.
The main figure shows the flows with the septum head. Flows with the
septumless head are the same except that the septum purge flow bypasses the
head (lower left).
Figure 22.
Stage 1. Sample injection
Septum purge
regulator
Column head pressure control loop
Flow
limiting
frit
Septum
head
FS
Proportional
valve 1
Flow
sensor
FS
132
SPR
Pressure
sensor
PS
Septumless
head
Septum
purge
vent
Split
vent
Trap
With the solenoid valve
closed, the sample and solvent transfer to the column.
Flows with septumless
head
PS
Solenoid
valve
closed
Proportional
valve 2
Glass liner
To detector
PTV splitless mode operation
Figure 23.
Flow
limiting
frit
Stage 2. Purging
Total flow
control loop
Pressure
sensor
Septum purge
regulator
PS
SPR
Septum
head
Column head pressure control loop
FS
Proportional
valve 1
Flow
sensor
After the sample has
transferred to the column,
the solenoid valve opens to
purge remaining solvent
vapor from the system.
Flows with septumless
head
FS
PS
Septum
purge
vent
Split
vent
Trap
Solenoid
valve
open
Proportional
valve 2
Glass liner
To detector
Septumless
head
133
PTV splitless mode operation
Figure 24.
Flows, pressures, and temperatures
SPLITLESS OPERATION
Split vent flow
Purge
flow
Saver
flow
Inlet pressure
Inlet is
pressure
controlled
Prep Start
Run Run
Purge
Time
Saver
Time
Stop
Run
Post
Time
Stop
Run
Post
Time
Post
Pres
Column flow program
Inlet
Pres
Prep Start
Run Run
Purge
Time
Prep Start
Run Run
Purge
Time
Inlet
temperature
Final
temp 1
Init
temp
134
PTV splitless mode operation
Temperature considerations
Cold splitless introduction
For cold splitless introduction, use an initial inlet temperature below the
normal boiling point of the solvent. For most solvents, starting the first
inlet temperature ramp at 0.1 minutes provides good transfer and
reproducibility. A program rate of 500C/min or higher is appropriate for
thermally stable analytes. A final temperature of 350C, held for 5
minutes, has quantitatively transferred up to C44 alkane.
A main advantage of temperature programmability is that the inlet can
be heated gently to transfer delicate analytes. If the oven temperature is
initially low enough to refocus the analytes on the column, the inlet
heating rate can be made slower (eg, 120C/min). This reduces thermal
degradation from the inlet and can improve peak shape and
quantitation.
For most applications of cold splitless, a single temperature ramp is
enough. The remaining ramps can be used to clean the liner or to
decrease the inlet temperature to prepare for the next injection.
Hot splitless introduction
For hot splitless introduction, select an initial temperature high enough
to volatilize the analytes. No additional temperature parameters are
required as the inlet will maintain the setpoint throughout the run.
Because of the small liner volume (about 120 ³L), the PTV cannot
contain vapor resulting from large liquid injection volumes. Injection
volumes greater than 1 ³L may overflow vapor from the inlet, causing
analysis variations. Cold splitless introduction avoids this problem.
135
PTV splitless mode operation
Control table parameters—splitless operation
Mode:
The current operating mode—splitless
Temp
Actual and setpoint inlet temperatures
Hold time at the initial inlet temperature.
Init time
Rate #
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final time #
Pressure
Final inlet temperature for ramps 1, 2, and 3.
Hold time at Final temp 1, 2, and 3.
Actual and setpoint inlet pressure in psi, bar, or kPa
Purge time The time, after the beginning of the run, when you want the
purge valve to open.
Purge flow The flow, in mL/min, from the purge vent, at Purge time.
You will not be able to specify this value if operating with your column
not defined.
Total flow The Total flow line displays the actual flow to the inlet
during a Pre-run (Pre-run light is on and not blinking) and during a run
before purge time. You cannot enter a setpoint at these times. At all
other times, Total flow will have both setpoint and actual values.
136
PTV splitless mode operation
Starting values
A successful splitless injection consists of these steps:
1. Inject the sample and temperature program the inlet to vaporize it.
2. Use a low column flow and low oven temperature to create a
solvent-saturated zone at the head of the column.
3. Use this zone to trap and reconcentrate the sample at the head of the
column.
4. Wait until all, or at least most, of the sample has transferred to the
column. Then discard the remaining vapor in the inlet—which is
mostly solvent—by opening a purge valve. This eliminates the long
solvent tail that this vapor would otherwise cause.
5. Raise the oven temperature to analyze the sample.
Some experimentation is needed to refine the operating conditions.
Table 16 provides starting values for the critical parameters.
Table 16.
Splitless Mode Inlet Parameters
Parameter
Allowed Setpoint Range
Suggested Starting
Value
Oven temperature
No cryo, ambient+10EC to
450EC
CO2 cryo, íEC to 450EC
N2 cryo, íEC to 450EC
Oven initial time
0 to 999.9 minutes
Inlet purge time
0 to 999.9 minutes
Liner volume*
x5
Column flow
Gas saver time
0 to 999.9 minutes
After purge time
Gas saver flow
15 to 1000 mL/min
15 mL/min greater
than maximum column flow
Inlet temperature
No cryo, oven temp + Û&
CO2 cryo, íÛ& to Û&
N2 cryo, íÛ& to Û&
Û& below solvent
boiling point for 0.1
min,
then ramp up
Û& below solvent
boiling point
| Inlet purge time
* Liner volume is about 120 ³L
137
PTV splitless mode operation
Procedure: Using splitless mode with the column defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter a purge time and a purge flow.
d. If desired, turn Gas saver on. Make certain the time is set after
the purge flow time.
FRONT INLET (HP PTV)
Mode:
Splitless
Temp
40
40 <
Init time
0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Purge time
2.0
Purge flow
50.0
Total flow
24.1
Gas saver
On
Saver flow
20.0
Saver time
5.00
Press [Mode/Type]
FRONT INLET MODE
Solvent vent
Split
*Splitless
<
Pulsed split
Pulsed splitless
If using gas saver,
set time after purge flow
time.
3. Press [Prep Run] (see page 13) before manually injecting a sample.
138
PTV splitless mode operation
Procedure: Using splitless mode with the column not defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter a purge time.
d. Set your total flow greater than the column flow plus the septum
purge flow (about 3 to 6 mL/min) to guarantee adequate column
flow.
FRONT INLET (HP PTV)
Mode:
Splitless
Temp
40
40 <
Init time
.0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Purge time
2.0
Tot flow
50.0
50.0
Press [Mode/Type]
FRONT INLET MODE
Solvent vent
Split
*Splitless
<
Pulsed split
Pulsed splitless
3. Press [Prep Run] (see page 13) before manually injecting a sample.
139
PTV splitless mode operation
Pulsed splitless mode operation
See page 128 for a discussion of the pulsed pressure modes.
Control table parameters—pulsed splitless operation
Mode:
The current operating mode—pulsed splitless
Temp
Actual and setpoint inlet temperatures
Init time
Rate #
Hold time at the initial inlet temperature.
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final time #
Final inlet temperature for ramps 1, 2, and 3.
Hold time at Final temp 1, 2, and 3.
Pressure Actual and setpoint inlet pressure before and after the
pressure pulse. It sets the starting point of a pressure program or the
fixed pressure if a program is not used.
Pulsed pres The inlet pressure you desire at the beginning of a run.
The pressure rises to this setpoint after [Prep Run] is pressed and
remains constant until Pulse time elapses, when it returns to Pressure.
Pulse time
Pressure returns to its normal setpoint at this time.
Purge time The time, after the beginning of the run, that you wish the
purge valve to open. Set purge time 0.1 to 0.5 minutes before pulse time.
Purge flow The flow, in mL/min, from the purge vent, at Purge time.
The column must be defined.
Total flow This is the total flow into the inlet, representing a total of the
column flow and the septum purge flow.
140
PTV splitless mode operation
Procedure: Using pulsed splitless mode with the column
defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed pres and Pulse time.
d. Enter the Purge time when you wish the purge valve to open.
e. Enter a Purge flow.
f.
Turn Gas saver on, if desired. Set the time after the purge flow
time.
Press [Mode/Type]
FRONT INLET (HP PTV)
Mode: Pulse spltless
Temp
40
40 <
Init time
0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Pulsed pres
30.0
Pulse time
1.0
Purge time
0.9
Purge flow
50.0
Tot flow
104
104
Gas saver
On
Saver flow
20.0
Saver time
5.00
FRONT INLET MODE
Solvent vent
Split
Splitless
Pulsed split
*Pulsed splitless
<
Set purge time 0.1 to 0.5
minutes
before pressure pulse time.
If using gas saver,
set time after purge flow
time.
3. Press [Prep Run] (see page 13) before manually injecting a sample.
141
PTV splitless mode operation
Procedure: Using pulsed splitless mode with the column not
defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Pulsed Splitless.
b. Set the inlet temperature and any desired ramps.
c. Enter values for Pulsed Pres and Pulse time.
d. Enter the Purge time when you wish the purge valve to open.
e. Enter a Purge flow.
Press [Mode/Type]
FRONT INLET (HP PTV)
Mode: Pulse spltless
Temp
40
40 <
Init time
0.1
Rate 1
600
Final temp 1
350
Final time 1
5.00
Rate 2 (off)
Pressure
9.1
9.1
Pulsed pres
30.0
Pulse time
1.0
Purge time
0.9
Tot flow
104
104
FRONT INLET MODE
Solvent vent
Split
Splitless
Pulsed split
*Pulsed splitless
<
Set purge time 0.1 to 0.5
minutes
before pressure pulse time.
3. Press [Prep Run] (see page 13) before manually injecting a sample.
142
PTV solvent vent mode operation
Part 4.
Using the Solvent Vent Mode
Flow patterns
The sample is injected into a cold inlet. If conditions are properly chosen
and the sample is suitable, analytes deposit in the inlet liner while the
solvent evaporates and is swept out. Large or multiple injections can be
used to concentrate sample in the inlet before transferring to the column
for analysis.
The main figure shows the flows with the septum head. Flows with the
septumless head are the same except that the septum purge flow
bypasses the head (lower left).
Figure 25.
Flow
limiting
frit
Stage 1. Sample and vent
Pressure
sensor
Total flow
control loop
Septum purge
regulator
Septum
purge
PS
SPR
vent
Column head pressure control loop
Septum
head
FS
Proportional
valve 1
Flow
sensor
During sampling and
venting, solenoid valve is
open. Inlet is at Init temp, at
or below solvent boiling
point. Solvent vapors are
swept out the vent, while
sample deposits on the liner
walls or packing.
Flows with septumless
head
FS
Split
vent
Trap
PS
Solenoid
valve
open
Proportional
valve 2
Glass liner
To detector
Septumless
head
143
PTV solvent vent mode operation
Stage 2.
Sample transfer
Septum purge
regulator
Column head pressure control
loop
Flow
limiting
frit
Septum
head
FS
Proportional
valve 1
Flow
sensor
PS
Septum
purge
vent
Pressure
sensor
Split
vent
Solenoid
valve
closed
Flows with septumless
head
Stage 3.
SPR
Trap
When solvent venting ends,
solenoid valve closes and inlet heats to Final temp 1.
The sample transfers to the
capillary column.
FS
PS
Proportional
valve 2
Glass liner
To detector
Septumless
head
Purge and cleanup
The solenoid valve opens again and the system returns to the Stage 1
configuration but with different setpoints. The PTV inlet is flushed.
Additional ramp rates are available to thermally clean the inlet or to
reduce inlet temperature after sample transfer. This can extend the life
of the liner.
144
PTV solvent vent mode operation
Temperature, pressure, and flow considerations
The solvent vent mode goes through three distinct pneumatic states;
venting, sample transfer, and purging. The vent portion allows the inlet
pressure and the vent flow to to be adjusted to optimize solvent
elimination. The transfer state mimics traditional splitless operation and
transports the analytes from the liner to the column. The purging mode
allows the user to prepare the inlet for the next run.
A fundamental difficulty with solvent vent mode is the potential loss of
volatile analytes with the solvent. Several solutions are possible for this
situation:
- The inlet liner can be packed with a more retentive material, such as
Tenax. This greatly improves volatile analyte recovery but may
impact recovery of higher boiling materials.
- Some of the solvent can be left in the liner when sample transfer
begins. The residual solvent acts like a stationary phase and retains
volatile material, but at the expense of a larger solvent peak.
- The inlet temperature can be reduced. This reduces the vapor
pressure of the volatile analytes and permits higher recoveries.
Solvent removal can be speeded up by:
- Reducing pressure in the inlet during sample introduction—the Vent
pressure parameter
- Increasing flow through the inlet—the Vent flow parameter
While all these possibilities do complicate use of the PTV, they provide
increased flexibility and new potential to solve difficult problems.
145
PTV solvent vent mode operation
Sequence of operations
These are the steps in a typical analysis using the solvent vent mode.
Step
Parameter
1.
Before injection
2.
Prep Run begins
3.
At Vent end time
4.
At Purge time
5.
At Saver time
Value
Flow at split vent — Either Purge flow or Saver flow
Inlet pressure
— Derived from column setpoint
The system is resting, with Purge flow (or Saver flow, if on) through the inlet.
Flow at split vent — Vent flow setpoint
Inlet pressure
— Vent pressure setpoint
Setpoints change to prepare for injection. When GC is ready, the sample is
injected. Inlet and oven temperature program Init times begin. Solvent venting
and analyte trapping begin.
Flow at split vent — None, solenoid valve closed
Inlet pressure
— Column pressure setpoint
Solvent venting ends, analyte transfer begins as inlet heats up.
Flow at split vent — Purge flow setpoint
Inlet pressure
— Column pressure setpoint
Analyte transfer ends, inlet is purged of residual vapor. Analysis begins.
Flow at split vent — Saver flow setpoint
Inlet pressure
— Column pressure setpoint
Analysis ends, gas flow reduced to save gas (if Saver is on).
Some important points
- The flow through the column is governed by the pressure in the inlet.
This is controlled, during the analysis part of the process, by the flow
or pressure setpoint or program entered for the column.
- The controlling times must be in the order shown; Vent end time
before Purge time before Saver time.
- Vent end time must occur before the inlet starts to heat and release
analytes.
- Purge time must occur before the oven begins to heat and move
sample through the column.
146
PTV solvent vent mode operation
Timelines
Time increases downward; all other quantities increase to the right.
Figure 26.
Time Relationships
Time
Oven temp
Inlet temp
Between runs
Prep Run
Start Run
Init time
Inlet pressure
(Controlled by
column flow or
pressure setpoint or program)
Vent
pressure
Split vent flow
Saver or
Purge
flow
Vent flow
Vent end time
Init time
Rate 1
(Inlet is
pressure
controlled)
Final temp 1
Final time 1
Purge time
Rate 1
Final temp 1
Final time 1
Saver time
Other
rates,
temps, and
times, if
desired.
Other
rates,
temps, and
times, if
desired.
Purge
flow
(Controlled by
column flow or
pressure setpoint or program)
Saver
flow
(if on)
147
PTV solvent vent mode operation
When is Start Run?
Both the inlet and oven temperature programs begin at Start Run. All
times—such as Purge time—are measured from Start Run. When does
Start Run occur?
- If the sample is injected manually, Start Run occurs when the user
presses the Start Run key.
- If a single injection per run is made using an autosampler, Start Run
occurs when the syringe carrier moves down to make the injection.
- If multiple injections per run are made using an autosampler, Start
Run occurs when the syringe carrier moves down to make the first
injection of the set. There are no Start Run signals for the rest of the
injections in the set.
These additional injections take time. The inlet and oven
temperature programs, mainly the Init time values, must be adjusted
to allow for this. So must the various time values that control the
inlet operation. This is discussed in more detail under Large Volume
injections, later in this chapter.
148
PTV solvent vent mode operation
Control table parameters—solvent vent operation
Mode:
The current operating mode—solvent vent
Temp
Actual and setpoint initial inlet temperatures
Init time The time, measured from Start Run, when the initial inlet
temperature hold ends. Usually greater than Vent end time.
Rate #
Temperature program rate for inlet thermal ramps 1, 2, and 3.
Final temp #
Final inlet temperature for ramps 1, 2, and 3.
Final time # Hold time at Final temp 1, 2, and 3. This time is a
duration; it is not measured from Start Run.
Pressure Actual and setpoint inlet pressure before and after the vent
period. It sets the starting point of column head pressure.
Vent pressure The inlet pressure during the vent period. By decreasing
the inlet pressure while venting, solvent elimination proceeds faster.
Also, the pressure reduction decreases the amount of carrier gas—and
solvent vapor—that enters the column during this time.
Users select from 0 to 100 psig. If 0 is chosen, the inlet uses the lowest
pressure possible at the given vent flow. Table 17 shows approximate
values for this minimum at various vent flows of helium. Pressures less
than those in the table are not possible unless the flow is reduced.
Table 17.
Minimum attainable pressures
Vent flow
(mL/min)
Actual vent pressure at “0“ psig
setpoint
Actual vent pressure at “0” kPa
setpoint
50
0.7
5
100
1.3
10
200
2.6
18
500
6.4
44
1000
12.7
88
149
PTV solvent vent mode operation
Vent flow The flow of carrier gas out the split vent during the vent
period. Higher flows sweep the liner more quickly and reduce the time
for solvent elimination. For most columns, 100 mL/min vent flow
eliminates solvent at an acceptable rate but puts minimal material on
the column.
Vent end time The time, measured from Start Run, when solvent
venting ends. For large volume injections, this time is normally greater
than the time for the injection to complete.
Purge time The time, measured from Start Run, when sample transfer
ends. It began at Vent end time.
Purge flow
Total flow
150
The flow of carrier gas to the inlet beginning at Purge time.
The Total flow displays the actual flow to the inlet.
PTV solvent vent mode operation
Procedure: Using solvent vent mode with the column defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Solvent vent.
b. Enter a vent pressure, a vent flow, and a vent end time.
c. Set the inlet temperature and ramps, as desired.
d. Enter a purge time and a purge flow.
e. If desired, turn Gas saver on. Make certain the time is set after
the purge time.
FRONT INLET (HP PTV)
Mode: Solvent vent
Temp
50
50 <
Init time
0.50
Rate 1
600
Final temp 1
400
Final time 1
5.00
Rate 2 (off)
Pressure
10.0
10.0
Vent pressure
5.0
Vent flow
100
Vent end time
0.40
Purge time
1.50
Purge flow
50
Total flow
24.3
Gas saver
On
Saver flow
20.0
Saver time
2.00
Press [Mode/Type]
FRONT INLET MODE
*Solvent vent
<
Split
Splitless
Pulsed split
Pulsed splitless
Should be less than Init time.
Must be greater than vent end
time.
Must be greater than purge time.
3. Press [Prep Run] (see page 13) before manually injecting a sample.
151
PTV solvent vent mode operation
Procedure: Using solvent vent mode with the column not
defined
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Solvent vent.
b. Enter a vent end time and a vent pressure.
c. Set the inlet temperature and ramps, as desired.
d. Enter a purge time. It must be greater than the vent end time.
e. Set total flow greater than the column flow plus the septum purge
flow (about 6 mL/min) to guarantee adequate column flow.
FRONT INLET (HP PTV)
Mode: Solvent vent
Temp
50
50 <
Init time
0.50
Rate 1
600
Final temp 1
400
Final time 1
5.00
Rate 2 (off)
Pressure
10.0
10.0
Vent pressure
5.0
Vent end time
0.40
Purge time
1.50
Tot flow
20.0
20.0
Press [Mode/Type]
FRONT INLET MODE
*Solvent vent
<
Split
Splitless
Pulsed split
Pulsed splitless
Should be less than Init time.
Must be greater than vent end
time.
3. Press [Prep Run] (see page 13) before manually injecting a sample.
152
PTV solvent vent mode operation
Large volume injection
Most vaporizing inlets are designed for liquid injections in the 1 to 5 ³L range.
With larger injections, the vapor cloud created when the sample vaporizes may
overflow the inlet and degrade the chromatography. For the PTV, the nominal
liner liquid capacities are:
Table 18.
Liner capacities
Liner
Nominal liquid capacity
Inertness
Open baffle
5 ³L
High
Glass wool
packed
25 ³L
Lower, because of greater surface
area
In the solvent vent mode, analytes are thermally trapped in the liner while the
solvent is removed. With the solvent gone, the liner volume can be used for
another injection. Injection can be repeated several times to concentrate the
analytes from a large sample volume. After injection and solvent removal, the
analytes are transferred to the column. This can replace the need for offline
concentrating and minimize loss of sample.
Multiple injections by an automatic sampler can be used with the PTV to
achieve large volume injection. A ChemStation controls the process.
Gas chromatograph requirements
-
Model 6890 GC with A.2.00 or later firmware
-
HP PTV
Automatic sampler requirements
-
Caution
Model G1512A controller with G1512A.01.08 or later firmware.
Model G1513A injector with G1513A.09.14 or later firmware. A second
injector can be mounted for synchronous injections to the rear inlet, but only
one PTV can be mounted and it must be in the front position.
Use of the 18593A or 18593B injection tower may damage the system.
-
Operates with or without sample tray, and with either standard or 8-sample
turret.
153
PTV solvent vent mode operation
ChemStation requirements
A GC or MSD ChemStation is necessary for multiple injection because
the needed parameters are not available through the HP 6890 GC
keyboard.
- GC ChemStation
or
Software revision A.04.02 or later
Software revision A.04.01 plus the software
provided with the PTV.
- MSD ChemStation Software revision A.03.00 or later
Control parameters—Injector configuration subscreen
Parameter
Range
Default
Syringe size
0.1 to 100 ³L
10 ³L
Nanoliter Adapter
Present or not present
Not present
Multiple Injections
Single or Multiple
Single
- Syringe size Full volume of the syringe.
- Nanoliter Adapter Controlled by a checkbox. If checked, indicates
that a nanoliter adapter is present on the injector. If not checked,
means that a nanoliter adapter is not present on the injector.
- Multiple Injections Controlled by a checkbox.If checked, the sampler
makes multiple injections into the inlet for each run according to the
other parameters. It issues a Start Run command at the first
injection only.
If not checked, the sampler makes one injection—and issues a Start
Run command—for each run. This is the default mode of operation.
154
PTV solvent vent mode operation
Control parameters—Injector screen
Parameter
Range
Default
Inject X ³L Y times
X: 0.1 to 0.5 x syringe volume
Y: 1 to 100
X: 0.1 x syringe volume
Y: 1
Delay between injections
0 to 100 seconds
0
Preinjection washes
0 to 15
0
Postinjection washes
0 to 15
0
Pumps
0 to 15
0
-
Inject X ³L Y times X is the amount to be injected; Y is the number of
injections to make. If the nanoliter adapter is checked on the Injector
Configuration screen, the range becomes 0.02 to 0.4 x syringe volume.
-
Delay A pause time, in seconds, between injections. This is added to the
minimum hardware cycle time.
-
Preinjection washes Number of times to wash the syringe with solvent
and/or sample before the first injection. No washes are performed before the
rest of the injections in a multiple injection set.
-
Postinjection washes Number of times to wash the syringe with solvent
after the last injection. No washes are performed after the rest of the
injections in a multiple injection set.
-
Preinjection pumps Number of times to pump the syringe plunger before
drawing up the measured sample. Pump are performed only before the first
injection of a multiple injection set.
Calculated values
The software calculates and displays:
-
On the Injector screen: Total Product of X (Volume per injection) and Y
(Injections per run).
-
On the Inlets screen: Estimated total injection time The approximate total
time, in minutes, to make a set of multiple injections based on the
parameters entered and the mechanical cycle time of the sampler. Includes
Delay between injections, pre- and post-injection dwell times, and viscosity
delays.
155
PTV solvent vent mode operation
An example
These values were used for a sample with a broad range of boiling
points.
General parameters
Name
Value
Sample
C10 to C44 hydrocarbons in hexane
Mode
Solvent vent
PTV liner
Glass wool packed
Injection volume
Injection speed
One 10.0 ³L injection (25 ³L syringe)
Column
30 m x 320 ³m x 0.25 ³m +3í HP p/n -í
Column flow
4 mL/min constant flow
Fast
Inlet parameters
Name
Value
Init temp
Û&
Rate 2 (off)
Init time
0.3 min
Pressure
15.6 psig
Rate 1
Û&PLQ
Vent pressure
0.0 psig
Final temp 1
Û&
Vent flow
100 mL/min
Final time 1
5 min
Vent end time
0.2 min
Rate 2
Û&PLQ
Purge time
2.0 min
Final temp 2
Û&
Purge flow
50 mL/min
Final time 2
0 min
Value
Oven parameters
Detector parameters
Name
Value
Name
Value
Init temp
Û&
Detector
FID
Init time
2.5 min
Detector temp
Û&
Rate 1
Û&PLQ
40 mL/min
Final temp 1
Û&
Hydrogen
flow
Air flow
Final time 1
10.0 min
Makeup (N2)
45 mL/min
Rate 2 (off)
156
Name
450 mL/min
PTV solvent vent mode operation
Figure 27.
Chromatogram From One 10 L Injection
C20
These results were compared with a splitless analysis of the same
sample, which should produce 100% recovery of all analytes. The data
showed that, under these conditions, compounds above C20 were
completely recovered and that the recovery was independent of injection
size; Compounds lower than C20 were partially vented with the solvent.
157
PTV solvent vent mode operation
Possible adjustments
Depending on what you are trying to accomplish, you have a number of
possible adjustments available.
- To eliminate more solvent
J Increase the vent end time, inlet initial time, and purge time.
This will not affect analytes that are quantitatively trapped but
will eliminate more of the solvent peak.
J Increase the vent flow to sweep the liner more rapidly with the
same inlet timing. Increasing vent flow raises vent pressure if it
is set to 0. This puts more solvent onto the column.
J Raise the inlet initial temperature to vaporize more solvent and
allow more to be eliminated. This also increases the loss of
volatile analytes since their vapor pressures also increase.
- To improve recovery of low boiling analytes
J Reduce inlet temperature to lower the vapor pressure of the
analytes and trap them more effectively. This also reduces solvent
vapor pressure and more time will be needed to eliminate it.
J Use a retentive packing in the liner. Materials such as Tenax
permit higher recovery of volatile analytes but may not release
higher boiling compounds. This must be considered if quantitation
on these high boiling peaks is desired.
J Leave more solvent in the liner. The solvent acts as a pseudo
stationary phase and helps retain volatile analytes. This must be
balanced against the detector’s tolerance for solvent.
158
PTV solvent vent mode operation
An example—continued
The single injection example shown on the last few pages makes it clear
that a 10 ³L injection does not overload the glass wool packed liner. This
means that multiple 10 ³L injections are possible.
It was decided to make 10 injections per run, each of 10 ³L size. This
would increase analytical sensitivity substantially. No adjustments were
made to improve recovery of the low boilers since the purpose of this
analysis was to detect and measure the high boiling components.
The ChemStation estimated that 10 injections would require a total of
1.3 minutes. The following timing changes were made:
Parameter
increased
from
to
Inlet Init time
0.3 minutes
1.6 minutes
Vent end
time
0.2 minutes
1.5 minutes
Purge time
2.0 minutes
3.0 minutes
Oven Init
time
2.5 minutes
3.0 minutes
The result is shown on the next page.
159
PTV solvent vent mode operation
Figure 28.
Chromatogram From Ten 10 L Injections
C20
160
PTV maintenance
Part 5.
Maintaining a PTV
Inlet adapters
The Graphpack-2M connector (the inlet adapter) at the bottom of the
inlet is sized to the column diameter. When a different diameter column
is to be installed, the adapter must be changed.
The adapter number is stamped on the side of the adapters. Select the
smallest hole diameter that will accept the column.
Table 19.
Inlet adapters
Column
ID
Inlet adapter
number
Quanti- HP part numty
ber
200 ³m
31
1
í
250 ³m
45
1
í
320 ³m
45
1
í
530 ³m
70
1
í
Procedure: Replacing inlet adapters
1. Unscrew the column nut from the adapter. Remove the nut and the
column from the inlet.
2. With a 6 mm wrench, remove the inlet adapter, being careful not to
lose the silver seal inside. Save the adapter for later use.
3. Select the appropriate inlet adapter for the column to be installed.
Insert a new silver seal (part number 51829763, pkg of 5) into the
adapter and screw the adapter onto the inlet fingertight. Use the 6
mm wrench to tighten the adapter an additional 1/16 to 1/8 turn.
Do not overtighten the adapter. The inlet can be damaged if the
adapter is forced. If the adapter leaks, check the silver seal and
replace it if necessary.
161
PTV maintenance
Procedure: Installing columns
Graphpack-2M ferrules are sized to the column outer diameter.
Table 20.
Columns and ferrules
Column ID
Graphpack ferrule hole ID
Quanti- HP part numty
ber
200 ³m
250 ³m
0.31 mm
0.40 mm
10
10
í
320 ³m
0.45 mm
10
í
530 ³m
0.70 mm
10
í
í
1. Place the appropriate Graphpack ferrule onto the column inlet end
and pull it at least 30 mm from the end.
2. With a glass knife or other fused silica cutter, remove approximately
10 mm from the column end to eliminate graphite contamination.
3. Position the ferrule so that it is 17 mm from the column end. Place a
small mark (typewriter correction fluid is useful) at the back of the
ferrule and, making sure that the column is correctly positioned,
insert the column end into the adapter.
2
cm
17 mm
0
Mark column here
162
PTV maintenance
4. Screw the column nut on fingertight. Using a 5 mm wrench, tighten
the column nut 1/8 to 1/4 turn. Be careful not to overtighten.
5. Check the connections for leaks. If there are any leaks at the column
adapter, tighten it slightly more with the open end wrench provided.
163
PTV maintenance
The septumless head
This sampling head uses a check valve instead of a septum to seal the
syringe entrance passage. It may be used with either automatic or
manual injection. Syringes must have 23 gauge needles (see the last
page of this chapter).
Procedure: Removing the septumless head
1. Cool the inlet to room temperature.
2. Disconnect the carrier gas line.
3. Unscrew the septumless head counterclockwise from the inlet.
4. Screw the new head onto the inlet. Tighten it 1/8 turn past finger
tight.
Carrier gas connection
5. Reconnect the carrier gas line.
6. Check all connections on the sampling head for leaks. If necessary,
tighten them again by hand.
164
PTV maintenance
Procedure: Cleaning the septumless head
Minor deposits from sample mixtures can collect in the head. Dust and
abraded material particles can enter together with the syringe needle,
eventually causing leaks. We recommend periodic cleaning.
1. Cool the inlet to room temperature.
2. Disconnect the carrier gas line and unscrew the head from the inlet.
3. Unscrew the sealing element from the head. Carefully remove the
Viton seal and the pressure spring. Do not use a sharp object to
extract the valve body—this can leave scratches that cause leaks.
Guide cap
Teflon ferrule, í
Kalrez seal, í
Valve body,
Carrier gas line
í
Pressure spring, í
Viton seal, í
Sealing element, í
4. Unscrew the guide cap from the head and remove the Teflon ferrule.
5. Insert a syringe with a 23 gauge needle carefully into the head to
press the valve body with the Kalrez seal slightly out of the head.
Carefully tap the head on a soft smooth surface so that the valve
body falls out completely or slips so far out that you can grasp it with
your fingers.
165
PTV maintenance
6. Remove the seal from the valve body.
7. Carefully clean all components in hexane.
8. Assemble the head in reverse order. Make sure that you work
absolutely lint-free and that the seals and the pressure spring are not
damaged.
9. Use this opportunity to check the Teflon ferrule. If it must be
replaced, see page 167 for instructions.
10. Check the entire system again for leaks; if necessary, carefully
retighten the guide cap slightly more with the syringe needle inserted
and/or replace the Kalrez seal.
If the head leaks when a syringe is inserted, the Teflon ferrule is the
problem. If the head leaks without a syringe inserted, the seals may
need to be replaced.
166
PTV maintenance
Procedure: Replacing the Teflon ferrule
1. Unscrew the guide cap from the septumless head and remove the
Teflon ferrule.
2. Push the guide cap and the new Teflon ferrule over the syringe
needle so that at least 10 mm of the needle tip is exposed.
3. Guide the end of the syringe needle into the septumless head until
the ferrule meets the septumless head.
4. Tighten the guide cap until resistance is first felt.
5. Check for leaks when the syringe needle has been fully introduced.
6. If necessary, carefully tighten the guide cap until the inlet stops
leaking.
167
PTV maintenance
The septum head
The septum head uses either a regular septum or a Merlin microseal to
seal the syringe passage. A stream of gas sweeps the inner side of the
septum and exits through the septum purge vent on the pneumatics
module.
Retaining nut
168
PTV maintenance
Procedure: Removing the septum head
The septum head connects to the inlet via a free-spinning retaining nut.
1. Cool the inlet to room temperature.
2. Use a 5/8 in. wrench to loosen the retaining nut on the septum head.
3. Gently remove the septum head assembly from the inlet. Be careful
not to overly bend the 1/16 inch lines. For best results, lift the head to
clear the inlet and then push it to either side to allow access.
4. To reinstall the septum head, gently align the head with the inlet
and manually engage the free-spinning nut to the inlet.
The nut should easily turn on to the inlet. If resistance is felt,
unscrew the nut and retry. Excessive force can irreparably damage
the inlet.
5. Tighten the retaining nut ½ turn past finger tight.
6. Check all connections for leaks. If necessary, the retaining nut can be
tightened an additional ¼ of a turn to eliminate leaks.
169
PTV maintenance
Procedure: Changing the septum
Either a regular septum or a Merlin microseal can be used with the
septum head.
If the inlet temperature is set below 40C, the Merlin microseal may not
seal effectively. For inlet temperatures below 40C, use a regular
septum for the inlet seal.
1. To replace the septum, cool the inlet to ambient temperature.
2. Using the inlet tool or manually, unscrew the septum cap or Merlin
cap counterclockwise. If the septum head begins to turn, support it
manually while removing the cap.
3. Remove the septum or Merlin microseal, taking care not to scratch
the interior of the septum head.
4. Install a new septum or Merlin microseal and the correct cap. When
installing a Merlin microseal, note that the side where the metal
parts are visible goes down.
Merlin
microseal and
cap
Standard
septum
and cap
5. Check for leaks out of the cap and tighten the cap if necessary.
170
PTV maintenance
Glass inlet liners
The liner is the chamber for sample deposition. Three kinds are
available:
Table 21.
Inlet liners
Type
Injection capacity
Inertness
Quantity
HP part number
Open baffled liner
lowest capacity
most inert
10
í
Liner packed with
silanized glass
wool
higher capacity
less inert
10
í
Unpacked liner, to
be packed by the
user
depends on the packing
10
í
171
PTV maintenance
Procedure: Replacing liners
1. Remove the head from the inlet See page 164 (septumless head) or
169 (septum head).
2. Grasp the liner by the Graphpack ferrule. Remove the liner and
ferrule.
3. Unscrew the assembly tool (HP part number G261780540) into two
pieces, the ferrule guide and the compression fitting.
Ferrule guide
Graphpack-3D ferrule
Compression
fitting
Open baffle liner
4. Slide the compression fitting onto the longer straight end of the new
liner with the threads pointing toward the end of the liner.
5. Place a Graphpack-3D ferrule on the same end of the the liner with
the recessed graphite end towards the compression fitting. Slide the
ferrule on so that about 2 mm of liner is exposed beyond the ferrule.
6. Slide the compression fitting up to meet the ferrule. Screw the ferrule
guide gently onto the compression fitting until it is fingertight.
172
PTV maintenance
7. Unscrew and remove the ferrule guide. Slide the compression fitting
off the other end of the liner. The ferrule should now be set with 1
mm of liner exposed. Check that the graphite within the ferrule is
flush with the top of the metal collar.
8. Insert the glass liner into the inlet from above until the unpacked
side of the ferrule rests on the top of the inlet.
9. Replace the sampling head and reconnect the lines, if necessary.
10. Check all connections for leaks. If necessary, tighten them again by
hand.
173
PTV maintenance
Consumables and replaceable parts
Description
Quantity
HP part number
1
*í
Service kit
1
í
Valve body
1
í
Pressure spring
1
í
Kalrez seal
1
í
Teflon guide
1
í
Sealing element
1
í
Graphpack-3D ferrule for liners
5
í
Assembly tool for Graphpack-3D ferrules
1
*í
Liner packed with silanized glass wool
10
í
Liner, open baffled
10
í
Liner, empty, for user packing
10
í
Graphpack-2M inlet adapter, 0.2 mm column id
1
í
Graphpack-2M inlet adapter, 0.32/0.25 mm column id
1
í
Graphpack-2M inlet adapter, 0.53 mm column id
1
í
Silver seal for Graphpack-2M inlet adapter
5
í
Nut for Graphpack inlet adapters
5
í
Ferrules for Graphpack-2M inlet adapter, 0.2 mm column id
10
í
Ferrules for Graphpack-2M inlet adapter, 0.25 mm column id
10
í
Ferrules for Graphpack-2M inlet adapter, 0.32 mm column id
10
í
Ferrules for Graphpack-2M inlet adapter, 0.53 mm column id
10
í
Septumless head assembly
more>
174
PTV maintenance
Description
Quantity
HP part number
5 ³L, 23 gauge fixed needle
1
í
10 ³L, 23 gauge fixed needle
1
í
10 ³L, Teflon-tipped plunger, 23 gauge fixed needle
1
í
10 ³L, Teflon-tipped plunger, 23 gauge removable needle
1
í
25 ³L, Teflon-tipped plunger, 23 gauge fixed needle
1
í
25 ³L, Teflon-tipped plunger, 23 gauge removable needle
1
í
50 ³L, Teflon-tipped plunger, 23 gauge fixed needle
1
í
50 ³L, Reflon-tipped plunger, 23 gauge removable needle
1
í
Merlin microseal starter kit (cap + 1 microseal)
1
í
Merlin microseal replacement
1
í
11 mm HP septa, red
25
í
Syringes
Septa and seals
175
6
Part 1. Using a Volatiles Interface
Split mode, 180
Understanding the pneumatics, 180
Procedure: Split mode, column defined, 185
Procedure: Split mode, column not defined, 186
Splitless mode, 187
Understanding the pneumatics, 187
Procedure: Splitless mode, 193
Direct mode, 194
Understanding the pneumatics, 194
Preparing for direct sample introduction, 196
Procedure: Disconnect split vent line, 196
Procedure: Configure GC for direct injection, 198
Procedure: Direct mode, 202
Part 2. Maintaining a Volatiles Interface
Procedure:
Procedure:
Procedure:
Procedure:
Procedure:
Procedure:
Installing columns, 204
Replacing/cleaning the interface, 208
Leak checking gas plumbing, 211
Leak checking, 212
Preparing for a leak test, 215
Correcting leaks, 216
Part 3. Connecting to an External Gas Sampler
Connecting the HP 7694 headspace sampler, 218
Connecting the HP 7695 purge and trap concentrator, 221
The Volatiles Interface
Chapter 6.
The Volatiles Interface
Part 1.
Using a Volatiles Interface
The volatiles interface provides a simple, reliable way to introduce a gas
sample into your gas chromatograph (GC) from an external device such
as the headspace, purge and trap, or air toxics samplers. The interface
has a small volume and is highly inert, thus ensuring high sensitivity
and resolution for applications requiring trace level detection.
Total flow to the interface is measured by a flow sensor and is divided
into two streams. One stream connects to the septum purge regulator;
the other connects to a frit block. At the frit block, the flow is further
divided. The first stream goes to the gas-phase sampler and from there is
introduced into the interface. The second stream, called the pressure
sensing line, passes through the frit block and is measured by a pressure
sensor. This stream also provides a trickle flow to the interface.
There are three modes of operation—split, splitless, and direct. The
pneumatics vary for each operating mode and are discussed in detail
later in this chapter. Table 22 summarizes some issues to consider when
choosing an operating mode. Specifications for the interface are also
listed.
178
Volatiles interface
Operation
Table 22.
Overview of volatiles interface
Mode
Sample type
(Concentration)
Sample to
column
Comments
Split
High
Very little,
most is
vented
Splitless
Low
All
Can switch to split mode
electronically.
Direct
Low
All
Must physically disconnect split
vent, plug the interface, and
reconfigure the GC. Maximizes
sample recovery and
eliminates possibility of
contamination to pneumatic
system.
Specifications
Silcosteel X-treated flow path
Volume:
32 mL
Internal dimensions:
2 mm by 10 mm
Maximum total flow to interface:
100 mL/min
Split range:
Dependent on column flow
Typically no split to 100:1
Temperature range:
10EC above ambient (with oven
at ambient) to 400 EC
Recommended temperature:
| transfer line temperature of
the external sampling device
179
Volatiles Interface
Split mode
Split mode
When you introduce a sample in the split mode, a small amount of the
sample enters the column while the major portion exits from the split
vent. The ratio of split flow to column flow is controlled by the user. The
split mode is primarily used for high concentration samples when you
can afford to lose most of the sample out the split vent and for samples
that cannot be diluted.
Understanding the pneumatics
During Pre Run, during sampling, and after sampling, total flow to the
interface is measured by a flow sensor and controlled by a proportional
valve. Flow at the head of the column is back-pressure regulated.
Pressure is sensed upstream from the proportional valve.
180
Volatiles interface
Split mode
Figure 29.
Pneumatics:
Split mode
Splitless mode: Idle or after sampling end
Total flow
control
loop
Carrier
supply
FS
SPR
Gas phase
sampler
Solenoid
valve
open
PS
Column
head
pressure
control loop
Split
Trap
vent
FS
Flow sensor
PS
Pressure
sensor
Frit block
(pressure sensing line)
SPR
Septum purge regulator
To
detector
Proportional valve
181
Volatiles Interface
Split mode
Using the control table
Mode:
The current operating mode—split
Temp
Actual and setpoint interface temperatures
Pressure
Actual and setpoint interface pressure
Split ratio The ratio of split flow to column flow. Column flow is set at
the Column 1 or Column 2 control table. This parameter is not available
if your column is not defined.
Split flow Flow, in mL/min, from the split vent. This parameter is not
available if your column is not defined.
Total flow
The total flow into the interface, both setpoint and actual.
Column defined
BACK INLET (VI)
Mode:
Split
Temp
250
250 <
Pressure
10.0
10.0
Split ratio
100
Split flow
76.6
Tot flow
80.3
80.3
Gas saver
On
Saver flow
20.0
Saver time
2.00
182
Column not defined
BACK INLET (VI)
Mode:
Split
Temp
250
250 <
Pressure
10.0
10.0
Tot flow
79.1
79.1
Volatiles interface
Split mode
Some setpoints are interdependent. If you change one setpoint, other
setpoints may change to compensate.
Table 23.
Split mode pneumatic setpoints
Column defined
When you
change:
These setpoints change:
Pressure
Column flow*
Split flow
Total flow
Column flow*
Pressure
Split flow
Total flow
Split flow
Split ratio
Total flow
Split ratio
Split flow
Total flow
Total flow
Split flow
Split ratio
Column not defined
Setpoints for Column flow, Split flow, and Split
ratio are not available.
You can change the setpoints for Total flow
and Pressure without affecting other setpoints.
*This setpoint appears in the column control table.
183
Volatiles Interface
Split mode
Operating parameters
Use the information in Table 24 to help you set up the operating
conditions for your interface.
Table 24.
Split mode operating parameters
Parameter
Allowed Setpoint Range
Suggested Starting
Value
Oven initial time
0 to 999.9 minutes
After sample on column
Interface
temperature
Ambient + 10EC to 400EC
transfer line
temperature
Gas saver time
0 to 999.9 minutes
After sample on column
Gas saver flow
15 to 100 mL/min
15 mL/min greater than
maximum column flow
|
Split ratio
Because of the interface’s small internal volume, the maximum total flow to the
interface is 100 mL/min. This maximum flow puts some restriction on the split ratio
you can set:
184
Column diameter
Column flow
Maximum split
ratio
Total flow
200 mm
1 mL/min
100:1
100 mL/min
530 mm
5 mL/min
20:1
100 mL/min
Volatiles interface
Split mode
Procedure: Operating in the split mode with the column defined
1. Verify that the split vent line is connected to your interface. Verify
that the [Config][Inlet] control table displays “split plumbed.”
2. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
3. Press [Front Inlet] or [Back Inlet].
Press [Mode/Type]
BACK INLET (VI)
Mode:
Temp
250
Pressure
10.0
Split ratio
Split flow
Tot flow
80.3
Gas saver
Saver flow
Saver time
Split ratio =
Split flow
Column flow
Split
250 <
10.0
100
76.6
80.3
On
20.0
2.00
BACK INLET MODE
Split
*Splitless
<
a. Scroll to Mode: and press [Mode/Type]. Select Split.
b. Set the interface temperature.
c. If you want a specific split ratio, scroll to Split ratio and enter that
number. The split flow will be calculated and set for you.
d. If you want a specific split flow, scroll to Split flow and enter that
number. The split ratio will be calculated and set for you.
e. If desired, turn on Gas saver. Set the Saver time after the sample
has been introduced.
f. If gas saver is on, be certain Auto prep run is On (see page 13) or
use the [Prep Run] key before introducing the sample.
185
Volatiles Interface
Split mode
Procedure: Operating in the split mode with the column not
defined
1. Verify that the split vent is connected to your interface. Verify that
the [Config][Inlet] control table displays “split plumbed.”
2. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
3. Press [Front Inlet] or [Back Inlet].
BACK INLET (VI)
Mode:
Split
Temp
250
250 <
Pressure
10.0
10.0
Tot flow
79.1
79.1
a. Set the temperature.
b. Set total flow into the interface. Measure flow out of the split vent
using a flow meter.
c. Subtract the split vent flow from the Total flow. Subtract the
septum purge flow (see “Septum purge” on page 15 for nominal
septum purge flows).
d. Calculate the split ratio. Adjust as needed.
Septum purge
Split vent
Front of GC
186
Volatiles interface
Splitless mode
Splitless mode
When you introduce a sample, the solenoid valve remains closed while
the sample enters the interface and is transferred to the column. At a
specified time after the sample is introduced, the solenoid valve opens.
Understanding the pneumatics
Before Pre Run, when the GC is preparing for sample introduction, total
flow to the interface is measured by a flow sensor and controlled by a
proportional valve. Column flow is controlled via back-pressure
regulation. See Figure 29.
During sampling, pressure upsets caused by switching valves in the
external sampling device can cause fluctuations in column flow rates. To
compensate for this, the interface is flow controlled during sampling
time. The sampling flow rate is calculated from the pressure setpoint
that is active when sample introduction begins. This flow control starts
when the GC goes into the Pre Run state (when your system is
automated and the Pre Run light is on or during manual operation when
you press [Prep Run]) and ends after the interface’s Sampling end
setpoint expires.
During this user-specified sampling period, the solenoid valve is closed.
Flow to the interface is measured by a flow sensor and controlled by a
proportional valve. See Figure 30.
After sampling end, the solenoid valve opens. Flow to the interface is
again measured by a flow sensor and controlled by a proportional valve
while column flow is controlled via back-pressure regulation. The purge
flow is controlled by the user. If desired, gas saver can be turned on at
the end of the run. See Figure 29.
187
Volatiles Interface
Splitless mode
Figure 30.
Splitless mode pneumatics: beginning of pre run to sampling end
(sample introduction in progress)
Total flow
control
loop
Carrier
supply
FS
SPR
Gas
phase
sampler
Solenoid
valve
closed
PS
Trap
FS
PS
188
Flow sensor
SPR
Pressure
sensor
Frit block
(pressure sensing line)
Septum purge
regulator
Proportional
valve
Split vent
To detector
Volatiles interface
Splitless mode
Using the control table
Mode:
The current operating mode—splitless
Temp
Actual and setpoint interface temperatures
Sampl’g end The sample introduction interval, in minutes. The flow
rate is calculated from the pressure setpoint that is active at the start of
sample introduction.
Set the sampling end setpoint 0.2 minutes longer than the time the
sampler needs to introduce the sample. For example, the HP 7694
headspace sampler has an Inject time parameter which controls how
long the valve remains in the inject position. If Inject time is 1 minute,
the sampling end setpoint should be set to 1.2 minutes. If you’re using
an HP 7695 Purge and Trap Concentrator, set the Sampling end setpoint
0.2 minutes longer than the Desorb time parameter.
If your column is defined and you specify a flow or pressure program for
your column, the ramp does not begin until after the sampling end
setpoint expires.
Pressure
Actual and setpoint interface pressure in psi, bar, or kPa.
Purge time The time, after the beginning of the run, when purging
resumes. Purge time must be greater than Sampling end.
Purge flow The flow, in mL/min, from the split vent at Purge time. You
will not be able access or to specify this value if operating with your
column not defined.
189
Volatiles Interface
Splitless mode
Total flow When your column is defined, Total flow displays the actual
flow to the interface. You cannot enter a setpoint. If your column is not
defined, Total flow will have both setpoint and actual values during purge
time. All other times, the actual flow to the interface is displayed.
Column defined
BACK INLET (VI)
Mode:
Splitless
Temp
250
250 <
Sampl’g end
1.00
Pressure
10.0
10.0
Purge time
4.00
Purge flow
15.0
Total flow
77.6
Gas saver
On
Saver flow
20.0
Saver time
8.00
190
Column not defined
BACK INLET (VI)
Mode:
Splitless
Temp
250
250 <
Sampl’g end
1.50
Pressure
10.0
10.0
Purge time
0.75
Tot flow
77.6
77.6
Volatiles interface
Splitless mode
Some setpoints in the flow system are interdependent. If you change one
setpoint, other setpoints may change to compensate.
Table 25.
Splitless mode pneumatic setpoints
Column defined
When you change:
These setpoints change:
Purging
Purge flow
Total flow**
Pressure
Total flow**
Column flow*
Column flow*
Pressure
Total flow**
Before and after sampling, not purging
Pressure
Column flow*
Total flow**
Column flow*
Pressure
Total flow**
During sampling: You cannot change pressure and flow
setpoints during sampling time.
Column not defined
Purging: You can change the Pressure and Total flow
setpoints; other setpoints are not affected.
Before and after sampling, not purging: You can change the
Pressure setpoint; other setpoints are not affected.
During sampling: You cannot change pressure and flow
setpoints during sampling time.
*This setpoint appears in the column control table.
**This value is actual only.
191
Volatiles Interface
Splitless mode
Operating parameters
A successful splitless injection consists of these steps:
1. Introduce a gas sample into the heated interface.
2. Use a low oven temperature while the sample collects at the head of
the column.
3. Set your sampling end time to allow the entire sample to be swept
out the sampler.
4. Set the purge time so that all the sample has collected on the column.
5. Begin your oven temperature program.
Table 26.
Splitless mode operating parameters
Parameter
Allowed Setpoint Suggested StartRange
ing Value
Oven initial time
0 to 999.9 minutes
| interface purge
time
Interface temperature
192
Ambient + 10EC to
400 EC
| transfer line
temperature
Interface sampling end
0 to 999.9 minutes
0.2 minutes longer
than introduction time
Interface purge time
0 to 999.9 minutes
Must be after Samplingend
Gas saver time
0 to 999.9 minutes
Must be after Purge
time
Gas saver flow
15 to 100 mL/min
15 mL/min greater
than maximum
column flow
Volatiles interface
Splitless mode
Procedure: Operating in the splitless mode
These instructions apply to both column defined and not defined.
1. Verify that the split vent line is connected to your interface. Verify
that the [Config][Inlet] control table displays “split plumbed.”
2. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
3. Press [Front Inlet] or [Back Inlet].
a. Scroll to Mode: and press [Mode/Type]. Select Splitless.
b. Set the interface temperature and a sampling end time.
Column defined
BACK INLET (VI)
Mode:
Splitless
Temp
250
250 <
Sampl’g end
1.5
Pressure
10.0
10.0
Purge time
1.75
Purge flow
15.0
Total flow
77.6
Gas saver
On
Saver flow
20.0
Saver time
2.00
Column not defined
BACK INLET (VI)
Mode:
Splitless
Temp
250
250 <
Sampl’g end
1.50
Pressure
10.0
10.0
Purge time
0.75
Tot flow
77.6
77.6
If using gas saver,
set time after purge flow
time.
c. If your column is defined, enter a purge time and purge flow.
Turn Gas saver on if desired. Set the Gas saver time after the
purge time and enter a Gas saver flow.
d. If your column is not defined, enter a purge time (purge flow is
not available). Set total flow greater than column flow plus
septum purge flow (about 6 mL/min) to guarantee adequate
column flow.
4. Make certain Auto Prep Run is On (see page 13) or use the [Prep
Run] key before introducing a sample.
193
Volatiles Interface
Direct mode
Direct mode
Direct sample introduction permits a quantitative transfer of analyte
without risking contamination to the pneumatic system. It provides the
sensitivity required for air toxics analyses. The interface’s minimal dead
volume also eliminates the potential interaction of solutes with poorly
swept, active surfaces.
To operate in the direct mode, you must physically disconnect the split
vent and reconfigure the GC. Instructions for performing these
procedures are discussed later in this chapter.
Understanding the pneumatics
Before Pre Run, the interface is forward pressure controlled; pressure is
sensed downstream from the flow proportional valve. See Figure 31a.
During sampling, pressure upsets caused by switching valves in the
external sampler can cause fluctuations in column flow rates. To
compensate for this, the interface is flow controlled during sampling
time. The sampling flow rate is calculated from the pressure setpoint
that is active when sample introduction begins. This flow control starts
when the GC goes into the Pre Run state (when your system is
automated and the Pre Run light is on or during manual operation when
you press [Prep Run]) and ends after the interface’s Sampling end
setpoint expires.
Flow to the interface is measured by a flow sensor and controlled by a
proportional valve. See Figure 31b.
After sampling end, the interface is forward pressure controlled; pressure
is sensed downstream from the proportional valve. See Figure 31a.
194
Volatiles interface
Direct mode
Figure 31.
Pneumatics for direct mode
a. Idle or after sampling end
FS
SPR
Forward
pressure
control
Gas phase
sampler
PS
Split line
disconnected
and pluggedTo detector
b. Pre run to sampling end
(sample introduction in progress)
Total flow
control
loop
FS
SPR
Gas phase
sampler
PS
Split line disconnected
and plugged
FS
PS
Flow sensor
SPR
Pressure
sensor
Frit block
(pressure sensing line)
Septum purge
regulator
To detector
Proportional valve
195
Volatiles Interface
Direct mode
Preparing your interface for direct sample introduction
Before you can operate your interface in direct mode, you must:
- Disconnect the split vent line
- Configure the GC for a direct injection
Procedure: Disconnecting the split vent line
WARNING
Be careful! The interface may be hot enough to cause burns.
Materials needed:
-
1/4-in. wrench
Blanking nut
5/16-in. or adjustable wrench
T-20 Torx screwdriver
1. Press [Front Inlet] or [Back
Inlet] and turn off the interface
temperature and pressure. Allow
the interface to cool.
BACK INLET (VI)
Direct injection
Temp
24
Sampling end
Pressure
0.0
Total flow
196
Off<
0.05
Off
0.0
Volatiles interface
Direct mode
2. If desired, remove the transfer line by
loosening the hex nut with a 1/4-in.
wrench. Remove the clamping plate from
the interface by loosening the captive
screw with a T-20 Torx screwdriver. Put
the plate in a safe place.
Remove
the
transfer
line
(optional)
3. Carefully lift the interface out of the
heater block.
Interface
Clamping
plate
4. Loosen the the hex nut connecting the
split vent line to the interface until you
can remove the line. Put the line aside.
You do not need to plug it.
Split
vent
Transfer line
Pressure
sensing
line
5. Install a blanking nut into the split line
port and finger tighten the nut. Tighten
the nut an additional 1/4 turn using two
wrenches in opposition, the adjustable
wrench on the interface and the 1/4-in
wrench on the nut.
Blanking
nut
197
Volatiles Interface
Direct mode
6. Place the interface in the heater
block. Replace the clamping plate
you removed in step no. 2 and
tighten the screw until snug. Do
not overtighten. If you removed
the transfer line, replace it.
Restore the GC to normal operating
conditions. Perform a leak test on
the interface fittings.
Clamping
plate
Procedure: Configuring for a direct injection
The GC cannot sense the presence of the split vent. When you disconnect
or reconnect the vent, you must configure the GC so that the pneumatics
work properly.
1. Press [Config] [Back Inlet] or [Config] [Front Inlet].
2. Press [Mode/Type].
3. Choose Split removed.
4. Press [Back Inlet] or [Front Inlet]. If your GC is correctly configured,
you will see the following display:
BACK INLET (VI)
Direct injection
Temp
250
Sampling end
Pressure
10.0
Total flow
198
If your interface is
250 <
0.05
10.0
0.0
configured
correctly, you will
see this display
Volatiles interface
Direct mode
Using the control table
Direct injection If your GC is configured correctly, you will see this
display. See “To configure your GC for a direct injection” for instructions.
Temp
Actual and setpoint interface temperatures
Sampl’g end The sample introduction interval, in minutes. The flow rate
is calculated from the pressure setpoint that is active at the start of
sample introduction.
Set the samplng end setpoint 0.2 minutes longer than the time the
sampler needs to introduce the sample. For example, the HP 7694
headspace sampler has an Inject time parameter which controls how
long the valve remains in the inject position. If Inject time is 1 minute,
the sampling end setpoint should be set to 1.2 minutes. If you’re using
an HP 7695 Purge and Trap Concentrator, set the Sampling end setpoint
0.2 minutes longer than the Desorb time parameter.
If your column is defined and you specify a flow or pressure program for
your column, the ramp does not begin until after the sampling end
setpoint expires.
Pressure Actual and setpoint interface pressure before a run and after
sampling time.
Total flow The actual flow to the interface. This is a reported value, not
a setpoint.
Column defined or
column not defined
BACK INLET (VI)
Direct injection
Temp
250
Sampl’g end
Pressure
10.0
Total flow
250 <
5.00
10.0
20.0
199
Volatiles Interface
Direct mode
Some setpoints in the flow system are interdependent. If you change one
setpoint, other setpoints may change to compensate.
Table 27.
Direct mode pneumatic setpoints
Column defined
When you change:
These setpoints change:
Before and after sampling
Pressure
Column flow*
Total flow**
Column flow*
Pressure
Total flow**
During sampling
You cannot change pressure and flow setpoints during
sampling time.
Column not defined
Before and after sampling
The Column flow* setpoint is not available.
You can change the pressure setpoint; other setpoints are not
affected.
During sampling
You cannot change pressure and flow setpoints during
sampling time.
*This setpoint appears on the column control
table.
**This value is actual only.
200
Volatiles interface
Direct mode
Operating parameters
Use the information in Table 28 to help you set up the operating
conditions for your interface.
Table 28.
Direct mode operating parameters
Parameter
Allowed Setpoint
Range
Oven initial
time
0 to 999.9 minutes
Interface
temperature
Ambient + 10EC to
400EC
Interface
sampling end
0 to 999.9 minutes
Suggested Starting Value
| interface
sampling end
| transfer line
temperature
0.2 minutes longer
than actual
sampling time
201
Volatiles Interface
Direct mode
Procedure: Operating in direct mode
These instructions apply to both column defined and not defined.
1. See Appendix A to verify that the column, carrier gas, and flow or
pressure program (if used) are configured correctly.
2. Press [Front Inlet] or [Back Inlet].
a. Verify that your GC is configured for a direct injection.
b. Set the interface temperature.
c. Set sampling end. Set 0.2 minutes longer than the sample
introduction time.
BACK INLET (VI)
Direct injection
Temp
250
Sampl’g end
Pressure
10.0
Total flow
250 <
0.05
10.0
0.0
3. Make certain Auto Prep Run is On (see page 13) or use the [Prep
Run] key before introducing a sample.
202
Volatiles interface
Maintenance
Part 2.
Maintaining a Volatiles Interface
Figure 32.
The volatiles interface parts breakdown
Top plate
(p/n G2319-00020)
Top insulation
(p/n G2319-20580)
Clamping plate
(p/n G2319-20540)
Volatiles interface
(p/n G2319-60505)
Upper ring
insulation
Heater/sensor wire
(p/n G2319-60503)
Heater block
(p/n G2319-60504)
Block insulation
(p/n G2319-20530)
Not shown:
Flow module, p/n G2319-60500
Pneumatic gang fitting assembly, p/n G2319-60501
203
Volatiles Interface
Installing columns
Procedure: Installing columns
WARNING
Wear safety glasses to protect your eyes from flying particles while
handling, cutting, or installing columns. Use care in handling these
columns to prevent puncture wounds.
WARNING
Be careful! The interface may be hot enough to cause burns.
Materials needed:
-
204
Column nut
Ferrule
Column cutter
Magnifying loop
Isopropanol
Tissue
Typewriter correction fluid
1/4-in. wrench
5/16-in. or adjustable wrench
Metric ruler
T-20 Torx screwdriver
1. Press [Oven] and set the oven to
35EC. Press [Front Inlet] or
[Back Inlet] and turn off the
interface temperature and
pressure. Allow the interface to
cool. When the oven
temperature reaches setpoint,
turn the oven off.
Volatiles interface
Installing columns
2. Disconnect the transfer line, if desired.
Loosen the nut with a 1/4-in. wrench
and remove the line. Remove the
clamping plate from the interface by
loosening the captive screw with a T-20
Torx screwdriver. Put the plate in a safe
place.
Remove the
transfer line
(optional)
3. Lift the interface out of the heater block.
Interface
Clamping
plate
Heater
block
4. From inside the oven, push the column
through the opening in the oven top.
5. Grab the column from the oven top.
Column
Push
column
through
this
opening
Column
205
Volatiles Interface
Installing columns
6. Place a capillary column nut and ferrule
on the column and prepare the column
end. If you need help with this step, see
Columns and Traps in the General
Information volume.
7. Position the column so it extends 6 mm
above the end of the ferrule. Mark the
column with typewriter correction fluid
at a point even with the column nut.
2
Ferrule
cm
0
6 mm
Column nut
Column
Mark column here
8. Insert the prepared column in the
interface and finger tighten the column
nut.
9. Adjust the column position so that the
correction fluid mark on the column is
even with the bottom of the column
nut.
Correction
fluid mark
206
Volatiles interface
Installing columns
10.Tighten the column nut an additional
1/4 to 1/2 turn using two wrenches in
opposition. Use the adjustable wrench to
hold the interface while you tighten the
column nut with the 1/4-in. wrench
until the column cannot be pulled from
the fitting with gentle pressure.
11.Replace the interface in the heater block.
Replace the clamping plate and tighten
the screw until snug. If you removed the
transfer line, reinstall it.
Clamping
plate
Tighten
1/4 turn
Interface
Heater
block
After the column is installed at both interface and detector, establish a flow of carrier gas
through the interface. Heat the interface to operating temperature. Retighten the fittings,
if necessary.
207
Volatiles Interface
Replacing or cleaning the interface
Procedure: Replacing or cleaning the interface
Materials needed:
- 1/4-in. or 7-mm wrench
- Sonicator or new interface
- T-20 Torx screwdriver
Preliminary Steps:
- If you have entered parameters that you do not want to lose, store them as a method.
- Allow the oven and interface to cool.
- Turn off all flows at the initial gas supply or set the flows to 0 in the inlet control
table.
1. Disconnect the transfer line. Loosen the
nut with a 1/4-in. wrench and remove
the line. Remove the clamping plate
from the interface by loosening the
captive screw with a T-20 Torx
screwdriver. Put the plate in a safe
place.
2. Lift the interface out of the heater block.
Transfer
line
Interface
Clamping
plate
Heater
block
208
Volatiles interface
Replacing or cleaning the interface
3. If a column is installed, removed
it. See Columns and Traps in the
General Information volume if
you need help with this step.
4. Remove the split and pressure
sensing lines by loosening the hex
nuts with the wrench.
Split
line
Sensing
line
Remove
the
column
5. Clean or replace the interface.
If you are cleaning the
interface, sonicate it twice and
then rinse.
6. Reinstall the split line and
pressure sensing lines and
finger tighten the hex nuts.
Tighten the hex nuts an
additional 1/4 turn with the
wrench.
Split
line
Sensing
line
209
Volatiles Interface
Replacing or cleaning the interface
7. Reinstall the column in the
interface. See Columns and Traps
in the General Information
volume for instructions.
8. Place the interface in the heater
block. Replace the clamping plate
you removed in step no. 1 and
tighten the screw until snug. Do
not overtighten.
Clamping
plate
Reinstall
the
column
Interface
9. Reinstall the transfer line. Finger
tighten the nut and then tighten
an additional 1/4 turn with the
wrench.
Transfer line
210
After the column is installed at
both interface and detector,
establish a flow of carrier gas
through the interface and maintain
it for 10 to 15 minutes. Check for
leaks. Heat the interface to
operating temperature and
retighten the fittings, if necessary.
Volatiles interface
Leak checking the gas plumbing
Procedure: Leak testing the gas plumbing
Leaks in the gas plumbing can affect chromatographic results
dramatically. The following procedure checks the flow system up to but
not including the interface flow module. If this portion of the system
proves to be leak-free, refer to the next procedure to check the interface
and interface module.
Liquid leak detectors are not recommended, especially in areas where
cleanliness is very important. If you do use leak detection fluid,
immediately rinse the fluid off to remove the soapy film.
WARNING
To avoid a potential shock hazard when using liquid detection fluid, be
careful not to spill leak solution on electrical leads, especially the
detector heater leads.
Materials needed:
- Electronic leak detector capable of detecting your gas type or liquid
leak detection fluid. If you use leak detection fluid, wipe off excess
fluid when you have completed the test.
-
Two 7/16-in. wrenches
1. Using the leak detector, check each connection you have made for
leaks.
2. Correct leaks by tightening the connections with the wrenches.
Retest the connections; continue tightening until all connections are
leak-free.
211
Volatiles Interface
Leak checking the interface
Procedure: Leak testing the system
There are several places in the interface-sampler system that can leak.
This procedure helps you determine, in general, if there is an
unacceptable leak in the system. If there is a leak, you should use an
electronic leak detector to pinpoint the component that is leaking.
WARNING
Be careful! The oven and interface may be hot enough to cause burns.
Materials needed:
- No-hole ferrule
-
7/16-in. wrench
-
Gloves (if the interface is hot)
-
1/4-in. or 7 mm wrench
2, 1/8-in. SWAGELOK caps
1. Complete the following preliminary steps:
a. If you have entered parameters that you do not want to lose,
store them as a method.
b. Cool the oven to room temperature and then turn it off.
c. When the oven is cool, turn off the interface pressure from the
keyboard.
d. Remove the column, if one is installed, and plug the column
fitting with the column nut and a no-hole ferrule (see p. 33).
2. Cap the septum purge and split vent fittings located on the flow
module with 1/8-in. Swagelock caps.
212
Volatiles interface
Leak checking the interface
3. Enter a pressure setpoint between 20 and 25 psi, or enter your
normal operating pressure if it is greater. Make sure that the
pressure at the initial gas supply is at least 10 psi higher than the
interface pressure. Wait a few minutes for the pressure to
equilibrate.
Press [Front
interface] or
[Back
interface]
Mode:
Temp
150
BACK INLET (VI)
Pressure
24.0
Split ratio
Split flow
Tot flow
0.0
Gas saver
Split
150 <
24.0
25
0.0
Off
Off
Enter a
pressure
setpoint
4. Turn the pressure off from the inlet control table. Because the
septum purge, split vent, and column fittings are capped, gas should
be trapped in the system and the pressure should remain fairly
constant. Turn the pressure off at the source if you want to isolate
the pneumatic system completely.
Monitor
the actual
pressure
display
Mode:
Split
Temp
150
150 <
BACK INLET (VI)
Pressure
24.0
Off
Split ratio
25
Split flow
0.0
Tot flow
0.0
Off
Gas saver
Off
Press [Off]
Because the pneumatics have been turned off, the alarm does not sound
even though there is no flow through the column.
213
Volatiles Interface
Leak checking the interface
5. Continue to monitor pressure for 10 to 15 minutes. You can use the
GC’s Stopwatch function. The pressure should drop approximately 1
psi during the first 1 to 2 minutes. After an initial pressure drop of
about 1 psi, the pressure should not drop more than 0.03 psi/min.
To access
stopwatch,
press [Time]
9:56:08
Last runtime
Next runtime
t=0:04.9
12 Dec 94
0.00
999.99
1/t=12.24
If the pressure drop is 0.03 psi/min or less, you can consider the
interface-gas sampler system leak-free.
If the pressure drops faster than the acceptable rate, you must check
the interface and sampler systems separately to determine the source
of the leak. See “Preparing the interface for a leak test” to create a
closed flow system, then return to this section and complete steps 3
to 5 again.
If you find a leak in the interface, refer to “Correcting Leaks” in this
chapter.
If the interface is leak-free, pressure check the sampling device. See
the operating manual for your sampler for instructions.
214
Volatiles interface
Preparing the interface for a leak test
Procedure: Preparing the interface for a leak test
To leak check the interface independent of the gas sampling device, you
must disconnect the sampler from the interface to isolate the interface
flow system from the sampler.
WARNING
Be careful! The oven and interface may be hot enough to cause burns.
Materials needed:
- 1/16-in. male GC nut and
-
Graphite/vespel ferrule
1. Disconnect the transfer line from the interface (see p. 37, step 1).
2. Disconnect the carrier line from the sampler (see page 218 if you
have a Headspace sampler or page 221 if you have a Purge and Trap
Concentrator.)
3. Prepare the end of the carrier line using the 1/16-in. male GC nut
and the graphite/vespel ferrule.
4. Connect the carrier line to the interface where you removed the
transfer line and tighten the nut finger tight and then tighten 1/4 to
1/2 turn with the 1/4-in. wrench.
5. Return to “Leak testing the system” in this chapter and repeat steps
3 to 5.
215
Volatiles Interface
Correcting leaks
Procedure: Correcting leaks
Materials needed:
- Electronic leak detector
- Tool that will tighten leaking fittings — 1/4-in., 5/16-in., or 7-mm
wrench
1. Use the electronic leak detector to check all areas of the interface
that are potential sources of a leak. Potential leak areas are:
—
—
—
—
The
The
The
The
capped purge vent
capped split vent
plugged column connection
area where the gas lines are plumbed to the interface
2. Correct leaks using the correct size wrench to tighten connections.
You may need to repeat the leak test again to check for leaks.
If the pressure drop is now 0.03 psi/min or less, you can consider the
interface system leak-free.
If the pressure drops faster than this, continue to search for leaks
and repeat the pressure test. If all fittings appear to be leak-free but
the interface system is still losing too much pressure, you may need
to replace the interface module. Contact your Hewlett-Packard
service representative.
216
Volatiles interface
External samplers
Part 3.
Connecting to an External Gas Sampler
Figure 33 illustrates a gas sampling device connected to the volatiles
interface.
Figure 33.
Flow diagram of an external sampling device
Carrier line
Gas-phase
sampler
Transfer line
217
Volatiles Interface
Headspace sampler
Procedure: Connecting the HP 7694 headspace sampler
Materials needed:
-
1/16-in. to 1/8-in. reducer
1/8-in. female Swagelok nut
1/8-in. back ferrule
1/8-in. front ferrule
Wrenches:
— One 7/16-in.
— Two 5/16-in.
— One 1/4-in.
— One 7-mm
1. Locate the GC’s carrier line
tubing labeled “supply” attached
to the volatiles interface, and
remove the carrier line from the
interface using a 1/4-in. wrench.
Carrier line
2. Remove the male fitting and
Vespel/graphite ferrule from the
carrier line. Keep the ferrule in a
safe place.
218
3. Get a 1/16-in. to 1/8-in. reducer,
and remove the female nut and
the metal front and back ferrules.
Keep the female nut in a safe
place.
Volatiles interface
Headspace sampler
4. Slide a 1/8-in. female Swagelok nut, a
1/8-in. back ferrule, and a 1/8-in. front
ferrule onto the unthreaded end of the
reducer.
5. Connect the reducer to the gas supply port
labeled “Carrier” on the back of the
headspace sampler by tightening the
1/8-in. female Swagelok nut using a
7/16-in. wrench. Tighten the nut 1/4 turn
past finger tight.
Carrier gas in
6. Slide the 1/16-in. female nut from step 3
and then the 1/16-in. Vespel/graphite
ferrule from step 2 onto the end of the
carrier line.
7. Connect the carrier line to the gas supply
port by holding the reducer with one
5/16-in. wrench while tightening the
1/16-in. female Swagelok nut with another
5/16-in. wrench. Tighten the fitting 1/4
turn past finger tight. Do not overtighten.
If the fitting leaks, tighten an additional
1/8 turn until it seals.
219
Volatiles Interface
Headspace sampler
8. Locate the headspace sampler’s
transfer line tubing.
9. Connect the transfer line (with
the preattached M5 nut and steel
ferrule) to the interface using a
7-mm wrench. Tighten the M5
nut 1/4 turn past finger tight. Do
not overtighten. If the nut leaks,
tighten an additional 1/8 turn
until it seals.
Transfer line
Transfer
line
Nut
220
Volatiles
interface
Volatiles interface
Purge and trap concentrator
Procedure: Connecting the HP 7695 purge and trap concentrator
Materials needed:
- 1/16-in. female Swagelok nut
- Vespel/graphite ferrule of the
-
1. Locate the GC’s carrier line
tubing labeled “supply” attached
to the volatiles interface, and
remove the carrier line from the
interface using a 1/4-in. wrench.
appropriate size for the
transfer line
Column cutter (fused silica)
Magnifying glass
5/16-in. and 1/4-in. wrenches
Typewriter correction fluid
Metric ruler
Carrier
line
2. Remove the male nut and
Vespel/graphite ferrule from the
carrier line. Keep the male nut
and ferrule in a safe place.
3. Slide a 1/16-in. female Swagelok
nut and then the Vespel/graphite
ferrule from step 2 onto the end
of the carrier line.
221
Volatiles Interface
Purge and trap concentrator
4. Connect the carrier line to the gas supply
port labeled “Carrier Gas” on the back of
the P&T concentrator using a 5/16-in.
wrench. Tighten the nut 1/4 turn past
finger tight. Do not overtighten. If the nut
leaks, tighten an additional 1/8 turn until
it seals.
5. Locate the P&T concentrator’s transfer
line tubing.
Carrier Gas
Transfer line
6. Slide the 1/16-in. male nut from step 2
and then an appropriate Vespel/graphite
ferrule onto the end of the transfer line.
Ferrule (size depends
on the transfer line
you’re using)
Nut
222
7. If you are using a nickel-plated transfer
line, proceed to step 8.
If you are using a fused-silica transfer
line, prepare the end of the fused silica
line. See “Columns and Traps” in the
General Information volume if you need
help with this step.
Volatiles interface
Purge and trap concentrator
8. Position the transfer line so that 2 mm of tubing is exposed in front of the ferrule, and
mark the transfer line with typewriter correction fluid at a point even with the nut.
cm
0
2
2 mm
Mark transfer line
here
7. Connect the transfer line to the volatiles interface by finger tightening the 1/16-in. male
nut while adjusting the transfer line’s position so that the correction fluid mark stays
aligned with the nut. Using a 1/4-in. wrench, tighten the nut 1/4 turn past finger tight.
Do not overtighten. If the fitting leaks, tighten an additional 1/8 turn until it seals.
Transfer line
Volatiles interface
Nut
223
7
Purged packed inlet, 226
Split/splitless inlet—split mode, 226
Split/splitless inlet—splitless mode, 226
Procedure: Configuring a nonEPC inlet, 227
Inlet control tables, 228
Column control tables, 229
Procedure: Setting carrier flow for the purged packed inlet, 230
Procedure: Setting flows for the split mode inlet, 231
Procedure: Setting flows for the splitless mode, 233
NonEPC Inlets
Chapter 7.
NonEPC Inlets
Controls for these inlets are located on a pneumatics module attached to
the left side of the GC.
Purged packed inlet
The only adjustment for this inlet is the carrier gas flow through the
column. Septum purge flow is set automatically based on the source gas
pressure. It can be measured at a vent on the front panel.
Split/splitless inlet—split mode
The carrier gas divides between the column and the split vent depending
on their relative flow resistances. A small amount of carrier gas sweeps
the lower side of the septum and exits through the septum purge control
and vent.
Split/splitless inlet—splitless mode
In a splitless injection, a valve is actuated by [Prep Run] that prevents
carrier gas from exiting the bottom of the inlet liner. Total flow does not
change, but most of it exits through the septum purge line. All carrier
gas that passes through the liner goes to the column—the sample is not
split.
At purge time, the valve switches to sweep out residual vapor in the
inlet. The system is now in the split configuration, with the purge flow
and residual vapor—mostly solvent—exiting through the split vent.
226
NonEPC inlets
Configuration
The GC is aware that a nonEPC inlet is present—it looks for the
heater/sensor connections—but does not know what kind. You must
supply this information through configuration.
Procedure: Configuring a nonEPC inlet
1. Press [Config], select Instrument., and [Enter].
CONFIG INSTRUMENT
Serial# US00100001
Auto prep run
Off
F inlet type:
S/SL <
B inlet type:
S/SL
2. Select the inlet and press [Mode/Type].
FRONT INLET TYPE
Purged packed
*Split/splitless
Cool on-column
<
Unknown
None
3. Select a type and [Enter].
4. Press [Config][Front Inlet] (or [Back Inlet]).
CONFIG FRONT INLET
Gas type
He <
5. Press [Mode/Type], select a gas, and [Enter].
227
NonEPC inlets
Inlet control tables
The inlet control tables for nonEPC inlets are similar to those for the
EPC versions except that flow and pressure settings are absent. See
Figure 34.
Figure 34.
NonEPC inlet control tables
Purged packed inlet
FRONT INLET (He)
Temp
150
150 <
Split/splitless inlet in split mode
FRONT INLET (He)
Mode:
Split <
Temp
150
150
Split/splitless inlet in splitless mode
FRONT INLET (He)
Mode:
Splitless <
Temp
150
150
Purge time
2.00
228
NonEPC inlets
Column control tables
When a nonEPC split/splitless inlet is used with a defined column, the
column control table becomes a calculator. Although you cannot control
flows from the keyboard, you can determine the flows to be set manually.
Column 1 (He)
Dim
30.0 m
Pressure
Calc flow
Calc velocity
320 u
0.0
0.0
0
Enter a pressure. Flow and average
linear velocity are calculated and displayed.
229
NonEPC inlets
Procedure: Setting carrier flow for the purged packed inlet
The internal flow path in the instrument is:
PURGED
PACKED
COLUMN
HEAD PRESSURE
CARRIER FLOW
INCR
IN
Inlet
Column
Detector
OUT
SEPTUM PURGE
VENT
1. Locate the knob labeled CARRIER FLOW. Turn it clockwise as far as
it will go. Do not force the knob; when it closes it comes to a slightly
“soft” stop.
2. Open the carrier gas cylinder valve and set the delivery pressure of
the two-stage regulator to 410 kPa (60 psi). If there is a local
regulator in the carrier gas line, set the cylinder regulator to 550 kPa
(80 psi) and the local regulator to 410 kPa (60 psi).
3. Attach a flow meter to the detector outlet. There should be no flow at
this time. If there is, turn the detector gas flows off from the
keyboard.
4. Turn the CARRIER FLOW knob in the INCR direction to turn the
carrier gas on. Adjust and measure to achieve the desired flow. If
necessary, increase the source pressure.
The septum purge is set automatically.
230
NonEPC inlets
Procedure: Setting flows for the split mode inlet
The internal flow path in the instrument is:
SPLIT
Split mode
INCR
COLUMN
HEAD PRESSURE
TOTAL FLOW SEPTUM PURGE
INCR
INCR
Inlet
IN
Column
Detector
OUT
SPLIT VENT PURGE VENT
1. Locate the knob labeled TOTAL FLOW. Turn it clockwise as far as it
will go. Do not force the knob; when it closes it comes to a slightly
“soft” stop.
2. Locate the knob marked SEPTUM PURGE. Turn it counterclockwise
to turn the flow off. There is no definite stop position; when the knob
turns freely (does not seem to be touching anything inside), it is off.
3. Open the carrier gas cylinder valve and set the delivery pressure of
the two-stage regulator to 410 kPa (60 psi). If there is a local
regulator in the carrier gas line, set the cylinder regulator to 550 kPa
(80 psi) and the local regulator to 410 kPa (60 psi). If you are using
small-bore capillary columns, you may have to use higher pressures.
4. Attach a flow meter to the detector outlet. There should be no flow at
this time. If there is, turn the detector gas controls off from the
keyboard.
231
NonEPC inlets
5. Turn the TOTAL FLOW knob in the
carrier gas flow on.
INCR direction to turn the
6. Turn the COLUMN HEAD PRESSURE knob in the INCR direction.
Adjust and measure to achieve the desired column flow. If you
cannot, increase TOTAL FLOW until you can. Use TOTAL FLOW for
coarse and COLUMN HEAD PRESSURE for fine adjustment.
7. Move the flow meter to the SPLIT VENT. Measure and adjust TOTAL
FLOW to achieve the desired split flow. If necessary, increase the
source pressure.
8. Move the flow meter to the PURGE VENT. Turn the SEPTUM PURGE
knob in the INCR direction to achieve the desired septum purge
flow.
9. Repeat steps 6, 7, and 8 until all flows are correct.
232
NonEPC inlets
Procedure: Setting flows for the splitless mode
The internal flow paths in the instrument are:
SPLIT
Splitless mode between
Prep Run and purge time
(ready for injection)
INCR
COLUMN
HEAD PRESSURE
TOTAL FLOW SEPTUM PURGE
INCR
INCR
Inlet
IN
Column
Detector
OUT
SPLIT VENT PURGE VENT
SPLIT
Splitless mode after purge time
(state for setting flows)
INCR
COLUMN
HEAD PRESSURE
TOTAL FLOW SEPTUM PURGE
INCR
INCR
Inlet
IN
Column
Detector
OUT
SPLIT VENT PURGE VENT
233
NonEPC inlets
1. Locate the knob labeled TOTAL FLOW. Turn it clockwise as far as it
will go. Do not force the knob; when it closes it comes to a slightly
“soft” stop.
2. Locate the knob marked SEPTUM PURGE. Turn it counterclockwise
to turn the flow off. There is no definite stop position; when the knob
turns freely (does not seem to be touching anything inside), it is off.
3. Open the carrier gas cylinder valve and set the delivery pressure of
the two-stage regulator to 410 kPa (60 psi). If there is a local
regulator in the carrier gas line, set the cylinder regulator to 550 kPa
(80 psi) and the local regulator to 410 kPa (60 psi). If you are using
small-bore capillary columns, you may have to use higher pressures.
4. Attach a flow meter to the detector outlet. There should be no flow at
this time. If there is, turn the detector gas controls off from the
keyboard.
5. Turn the TOTAL FLOW knob in the
carrier gas flow on.
INCR direction to turn the
6. Turn the COLUMN HEAD PRESSURE knob in the INCR direction.
Adjust and measure to achieve the desired column flow. If you
cannot, increase TOTAL FLOW until you can. Use TOTAL FLOW for
coarse and COLUMN HEAD PRESSURE for fine adjustment.
7. Move the flow meter to the SPLIT/SPLITLESS INLET VENT. Measure
and adjust TOTAL FLOW to achieve the desired split flow. If
necessary, increase the source pressure.
8. Move the flow meter to the SEPTUM PURGE VENT. Turn the
SEPTUM PURGE knob in the INCR direction to achieve the desired
septum purge flow.
9. Repeat steps 6, 7, and 8 until all flows are correct.
234
Appendix A
Preparing for analysis, 236
To configure the carrier gas, 237
To select a column mode, 238
To set the initial flow or pressure or average linear velocity, 239
To enter a pressure or flow program, 240
Configuration Information
Appendix A:
Configuration Information
Preparing for analysis
All operating procedures begin with the four steps below. Note that there
are two variations of step 2, one for column defined and one for column
not defined.
The rest of the material in this appendix provides the details of these
steps. It is copied from the General Information volume and printed here
as a convenience to eliminate jumping back and forth between the two
books.
1.. Verify that a column is installed and the correct liner is in the inlet.
2.. Configure the column. Press [Config][Col 1] or [Config][Col 2].
a. To define the column, enter the dimensions requested.
or
b. To leave the column not defined, enter 0 for either column length
or column diameter.
3.. Press [Col 1] or [Col 2]. Verify that the gas type in the title line is
correct. Change if necessary.
4.. Specify a column flow or pressure mode and a starting flow or
pressure. Enter a flow or pressure program, if desired.
To configure the carrier gas
1.. Press [Config] [Front Inlet] or [Config] [Back Inlet].
2.. Press [Mode/Type] to see the carrier gas menu.
CONFIG FRONT INLET
Gas type
He <
Carrier gas type.
Press [Mode/Type] to get
menu.
FRONT INLET GAS
*Helium
Hydrogen
Nitrogen
Argon methane 5%
<
3.. Scroll to the gas you will use. Press [Enter].
This completes carrier gas configuration. See the Inlets volume for more
detail.
237
To select a column mode
1.. Press [Col 1] or [Col 2].
2.. Scroll to the Mode line.
3.. Press [Mode/Type] to see the column mode menu.
COLUMN 1 (He)
Dim 30.0 m
230 u Pressure
0.0
Off
Flow
0.0
Velocity
0.0
Mode: Constant flow
<
Here is your carrier gas choice.
These are the column length and
inside diameter that you entered.
Press [Mode/Type] to see
the Column Mode menu.
COLUMN 1 MODE
Constant pressure
*Constant flow
Ramped pressure
Ramped flow
<
4.. Scroll to the column mode you want. Press [Enter].
This completes the column mode selection. Next you must specify the
inlet conditions either during the entire run (if you selected either of the
constant modes) or at the beginning of the run (if you selected either of
the ramped modes).
To set the initial flow or pressure or average linear
velocity
1.. Press [Col 1] or [Col 2].
COLUMN 1
Dim 50.0 m230 u Pressure
2.5
2.5
Flow
10.0
Velocity
74
Mode: Constant flow
<
The column length and inside diameter.
You set one of these. The GC
calculates the other two.
The column mode; see below.
The control table will have one of these, depending on the column
mode selected:
Mode: Const flow
Mode: Const pressure
<
<
Mode: Ramped flow
Init flow
Init time
Rate 1
Final flow
Final time
Rate 2 (Off)
<
4.0
2.0
0.5
18.0
12.0
0.00
Mode: Ramped pressure <
Init pressure 10.0
Init time
1.0
Rate 1
1.0
Final pressure125.0
Final time
15.0
Rate 2 (Off)
0.00
2.. Scroll to the Pressure or Flow or Velocity line.
3.. Type the desired initial value, followed by [Enter]. The GC computes and
displays the other two values. Adjust them, if you choose to, by repeating
steps 2 and 3. Note that changing any one changes all three.
This completes setting the initial carrier gas condition.
239
To enter a pressure or flow program
1.. Press [Col 1] or [Col 2].
COLUMN 1
Dim
50.0 m 250 u
Pressure
10.0
10.0
Flow
0.0
Velocity
0.0
Mode:
Ramped pres
Init Pres
10.0
Init time
1.5
Rate 1
0.5
Final pres 1
20.0
Final time 1
2.5
Rate 2 (Off)
0.00
Pressure (in this example) is
the controlled setpoint; the
others are reported values.
Because Mode is Ramped
pres, the ramp is given in
pressure units.
2.. Scroll to Init Pres (or Init flow). Type the desired value and press
[Enter].
3.. Similarly, enter a value for Init time. This completes the initial
(constant pressure) part of the program.
4.. To begin a ramp, enter a positive value for Rate 1. It does not matter
whether you are programming up or down—the rate is always
positive.
5.. If Rate 1 is zero, the program ends here. If you enter any other value,
the Final value lines for the first ramp appear and the cursor moves
to the line.
6.. Enter values for Final pres 1 (or Final flow 1) and Final time 1. This
completes the first ramp.
7.. To enter a second (or third) ramp, scroll to the appropriate Rate line
and repeat steps 5 and 6.
A
Adapter, PTV inlet, replacing, 161
Auto Prep Run, 14
C
Carrier gas, flow rate and column size, 4
Cleaning
cool oncolumn inlet, 106
PTV inlet, septumless head, 165
purged packed inlet, 81
split/splitless inlet, 54
Volatiles Interface, 208
Column
control table, 7
mode selection, 238
PTV inlet, installation, 162
Volatiles interface, installation, 204
Configuration
carrier gas, 237
nonEPC inlet, 227
PTV inlet, 120
Volatiles Interface, direct mode, 198
Control table
column, 7
column undefined, purged packed inlet, 65
nonEPC inlet, 228, 229
packed column, 9
PTV inlet
pulsed split mode, 129
pulsed splitless mode, 140
solvent vent mode, 149
split mode, 125
splitless mode, 136
purged packed inlet, 65
split/splitless inlet
pulsed split mode, 31
pulsed splitless mode, 33
split mode, 22
splitless mode, 26
undefined column, 9
Volatiles Interface
direct mode, 199
lit
d 182
cleaning, 106
cooling tower, 88, 105, 107
manual injection, 93
correcting leaks, 113
CryoBlast, 94
cryogenic considerations, 95
duckbill septum, 88
fused silica needle, 101, 102
hardware, 85
hardware problems, 100
injection with septum nut, 87
inserts, 87
installing insert, 90
leak testing, 110
gas plumbing, 109
maintenance, 98
manual injection, septum nut, 92
needles, 87
operation, 97
septum changing, 103
septum nut, 89, 105, 107
setpoint ranges, 95
temperature programming, 95, 96
track oven mode, 94
Cooling tower, cool oncolumn inlet, 88, 105,
107
Cryo shutdown, PTV inlet, 122
CryoBlast, cool oncolumn inlet, 94
D
Direct mode, Volatiles Interface, 194, 202
control table, 199
parameters, 201
F
Ferrule, Teflon, replacing, 167
Flow
initial, 239
program, 240
PTV inlet, solvent vent mode, 145
G
Gas, carrier, configuration, 237
Gas sa er 11
Headspace sampler, Volatiles Interface, connection, 218
Hydrogen, 2
I
Initial flow, 239
Volatiles Interface, 212
gas plumbing, 211
preparation, 215
Liners
PTV inlet, 171
replacing, 172
purged packed inlet, 59, 61
split/splitless inlet, 19
Initial linear velocity, 239
Initial pressure, 239
Injector configuration, large volume injection,
154
Injector parameters, large volume injection,
155
Inlet
nonEPC, configuration, 227
split/splitless, septum, 18
Inlets, overview, 3
Inserts
cool oncolumn inlet, 87
purged packed inlet, 59, 63
Installing columns
PTV inlet, 162
Volatiles Interface, 204
M
Maintenance
cool oncolumn inlet, 98
PTV inlet, 161
purged packed inlet, 67
split/splitless inlet, 35
Volatiles Interface, 203
Manual injection, cool oncolumn inlet
cooling tower, 93
septum nut, 92
Merlin microseal, 170
N
Needle size, cool oncolumn inlet, 91
Needles, fused silica, cool oncolumn inlet, 101,
102
L
Large volume injection
ChemStation requirements, 154
example, 156
GC requirements, 153
sampler requirements, 153
Leak correction
cool oncolumn inlet, 113
purged packed inlet, 80
split/splitless inlet, 53
Volatiles Interface, 216
Leak testing
cool oncolumn inlet, 110
gas plumbing, 109
purged packed inlet
EPC, 75
gas plumbing, 74
O
Oring changing
purged packed inlet, 72
split/splitless inlet, 39, 41
P
Prep Run, 11, 13
Auto, 14
key, 13
Pressure
initial, 239
program, 240
select units, 5
solvent vent mode, 145
i
i
Changing septum, 89, 104
Changing septum nut, 89
Checking needle/column size, 91
Cleaning inlet, 106
Correcting leaks, 113
Installing fused silica needle, 102
Installing inserts, 90
Leak testing gas plumbing, 109
Leak testing inlet, 110
Manual injection with cooling tower, 93
Manual injection with septum nut, 92
Operating, 97
Programming temperature, 96
Replacing fused silica needle, 101
Gas saver, 12
NonEPC inlets, Configuration, 227
NonEPC purged packed, Setting carrier flow,
230
NonEPC split/splitless
Setting split mode flows, 231
Setting splitless mode flows, 233
Pressure units, Select psi, kPa, bar, 5
PTV
Changing septum, 170
Cleaning septumless head, 165
Installing columns, 162
Pulsed split mode, column defined, 130
Pulsed split mode, column not defined, 131
Pulsed splitless mode, column defined, 141
Pulsed splitless mode, column not defined,
142
Removing septum head, 169
Removing septumless head, 164
Replacing inlet adapters, 161
Replacing liners, 172
Replacing Teflon ferrule, 167
Solvent vent mode, column defined, 151
Solvent vent mode, column not defined, 152
Split mode, column defined, 126
Split mode, column not defined, 127
Splitless mode, column defined, 138
Splitless mode, column not defined, 139
Purged packed
Changing Oring, 72
Changing septum, 68
Cleaning inlet, 81
Correcting leaks, 80
Installing glass inserts, 63
Installing liners, 61
Using undefined capillary columns, 66
Split/splitless
Changing liners, 19
Changing Oring, 41
Changing septum, 37
Cleaning inlet, 54
Correcting leaks, 53
Leak testing EPC inlet, 47
Leak testing gas plumbing, 46
Leak testing nonEPC inlet, 51
Pulsed split mode, 32
Pulsed splitless mode, 34
Replacing base seal, 44
Split mode, column defined, 23
Split mode, column not defined, 24
Splitless mode, column defined, 28
Splitless mode, column not defined, 29
Volatiles interface
Configuring for direct injection, 198
Connecting headspace sampler, 218
Connecting purge and trap concentrator,
221
Correcting leaks, 216
Direct mode, 202
Disconnecting split vent line, 196
Installing columns, 204
Leak testing gas plumbing, 211
Leak testing system, 212
Preparing for leak test, 215
Replacing or cleaning interface, 208
Split mode, column defined, 185
Split mode, column not defined, 186
Splitless mode, 193
Programming
column flow, 240
cool oncolumn inlet temperature, 95
inlet pressure, 240
PTV inlet, 116, 161
changing septum, 170
configuration, 120
cooling, 120
cryo shutdown, 122
heating, 119
installing columns, 162
large volume injection
ChemStation requirements, 154
example, 156
GC requirements, 153
injector configuration, 154
pulsed split mode
column defined, 130
column undefined, 131
control table, 129
pulsed splitless mode
column defined, 141
column undefined, 142
control table, 140
replaceable parts, 174
replacing adapters, 161
replacing liners, 172
sampling heads, 118
septum head, 168
removing, 169
septumless head
cleaning, 165
removing, 164
solvent vent mode, 143
column defined, 151
column undefined, 152
control table, 149
large volume injection, 153
order of operations, 146
Start Run, 148
temperature, pressure and flow, 145
timelines, 147
split mode, 123
column defined, 126
column undefined, 127
control table, 125
split modes, temperatures, 124
splitless mode, 132
column defined, 138
column undefined, 139
control table, 136
starting values, 137
system components, 117
system requirements, 116
Teflon ferrule, replacing, 167
temperature, 135
changing Oring, 72
changing septum, 68
cleaning, 81
column defined, 66
column undefined, 66
control table, column defined, 65
correcting leaks, 80
inserts, 59
installing inserts, 63
installing liners, 61
leak testing
EPC, 75
gas plumbing, 74
nonEPC, 78
liners, 59
maintenance, 67
nonEPC, 230
packed column, control table, 65
packed columns, 66
R
Retention gap, 94
S
Sampler connection, Volatiles Interface, 217
Sampling heads, PTV inlet, 118
Septum changing
cool oncolumn inlet, 89, 103, 104
PTV inlet, 170
purged packed inlet, 68
split/splitless inlet, 36, 37
Septum head, PTV inlet, 168
removing, 169
Septum nut, cool oncolumn inlet, 87, 105, 107
changing, 89
Pulsed modes, PTV inlet, 128
Septum purge, 15
Pulsed split mode, PTV inlet
column defined, 130
column undefined, 131
Septum tightening, 18
Pulsed splitless mode, PTV inlet
column defined, 141
column undefined, 142
control table 140
Septumless head, PTV inlet
cleaning, 165
removing, 164
Setpoints, cool oncolumn inlet, 95
Shutdown, cryo, 122
PTV inlet
column defined, 151
column undefined, 152
control table, 149
large volume injection, 153
Split mode
PTV inlet, 123
column defined, 126
column undefined, 127
split/splitless inlet, 21
column defined, 23
column undefined, 24
Volatiles Interface, 180
column defined, 185
column undefined, 186
parameters, 184
Split vent line, Volatiles Interface, disconnect,
196
Split/splitless inlet, 18
changing Oring, 39, 41
changing septum, 36, 37
cleaning, 54
correcting leaks, 53
leak testing, 46
EPC, 47
nonEPC, 51
liners, 19
maintenance, 35
nonEPC, 229
pressure, 18
pulsed modes, 30
pulsed split mode, 32
control table, 31
pulsed splitless mode, 34
control table, 33
replacing base seal, 43, 44
septum tightening, 18
split mode, 21
control table, 22
nonEPC, 231
splitless mode, 25
column defined, 28
column undefined, 29
control table, 26
nonEPC, 233
parameters, 27
Splitless mode
PTV inlet, 132
column undefined, 29
Volatiles Interface, 187, 193
parameters, 192
Start Run, PTV inlet, solvent vent mode, 148
T
Teflon ferrule, PTV inlet, replacing, 167
Temperature, PTV inlet, 135
solvent vent mode, 145
split modes, 124
Temperature programming, cool oncolumn
inlet, 95, 96
Timelines, PTV inlet, solvent vent mode, 147
Track oven mode, cool oncolumn inlet, 94
U
Using hydrogen, 2
V
Volatiles Interface, 178
cleaning or replacing, 208
connection to sampler, 217
correcting leaks, 216
direct mode, 194, 202
configuration, 198
control table, 199
disconnect split vent line, 196
parameters, 201
installing columns, 204
leak testing, 212
gas plumbing, 211
preparation, 215
maintenance, 203
overview, 179
split mode, 180
column defined, 185
column undefined, 186
control table, 182
parameters, 184
split vent line, disconnecting, 196
Printed on recycled paper.
This product is recyclable.
Manual Part No. G1530-90450
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