5890_Series_II_Operating_Manual

Operating Manual
HP 5890 Series II and
HP 5890 Series II Plus
©Hewlett-Packard Company
1989,1990, 1991, 1992, 1993,
1994
All Rights Reserved.
Reproduction, adaptation, or
translation without permission
is prohibited except as
allowed under the copyright
laws.
HP part number
05890-90261
First Edition, Jun 1989
Second Edition, Oct 1989
Third Edition, Jan 1990
Fourth Edition, Oct 1990
Fifth Edition, Oct 1991
Sixth Edition, Sep 1992
Seventh Edition, Jun 1993
Eighth Edition, Nov 1993
Ninth Edition, Jul 1994
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 5890 Series II and HP
5890 Series II Plus are IEC
(International
Electrotechnical Commission)
Safety Class 1 instruments.
This unit has been designed
and tested in accordance with
recognized safety standards.
Whenever the safety
protection of the HP 5890
Series II has been
compromised, disconnect the
unit from all power sources
and secure the unit against
unintended operation.
Safety Symbols
This manual contains safety
information that should be
followed by the user to ensure
safe operation.
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.
Little Falls Site
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
If Test and Measurement
Equipment is operated with
unscreened cables and/or used
for measurements in open
set-ups, users have to assure
that under these operating
conditions the Radio
Interference Limits are still
met at the horder of their
premises.
The following information is
provided to comply with the
requirements of the German
Sound Emission Directive
dated January 18,1991
Sound pressure Lp < 70db(A)
During normal operation
At the operator position
According to IS0 7779 (Type
Test)
When operating the HP 5890
Series II with cryo valve
78 db(A) during cryo valve
operation for short burst
pulses.
Contents
Chapter 1 — Getting Started . . . . . . . . . . . . . . . . . . . . . . . .
9
Installation checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daily startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Daily shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HP 5890 signal output (full scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General safety considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
11
11
12
12
12
13
Chapter 2 — Installing Columns . . . . . . . . . . . . . . . . . . . . .
15
Preparing fused silica capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing split/splitless capillary inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparing packed metal columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing l/4-and l/8-inch metal columns in packed inlets . . . . . . . . . . . . . . . . . .
Installing l/4-inch glass columns in packed inlets . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing capillary columns in packed inlets. . . . . . . . . . . . . . . . . . . . :. . . . . . . . . .
Installing capillary columns in split/splitless capillary inlets . . . . . . . . . . . . . . . . .
Installing l/4-inch metal columns in FID’s and NPD’s . . . . . . . . . . . . . . . . . . . . . .
Installing l/8-inch metal columns in FID’s and NPD’s . . . . . . . . . . . . . . . . . . . . . .
Installing capillary columns in FID’s and NPD’s . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installing an l/8-inch metal column in a thermal conductivity detector . . . . . . .
Installing a capillary column in a thermal conductivity detector . . . . . . . . . . . . .
Installing a l/4-inch glass column in an electron capture detector . . . . . . . . . . . .
Installing a capillary column in an electron capture detector . . . . . . . . . . . . . . . .
Installing an l/8-inch metal column in aflame photometric detector . . . . . . . . .
Installing a capillary column in aflame photometric detector . . . . . . . . . . . . . . . .
17
19
20
23
25
27
Chapter 3 — Setting Heated Zone Temperatures . . . . . . .
49
Operating limits for heated zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting oven temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying oven temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using cryogenic oven cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Programming oven temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting inlet and detector temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying inlet and detector temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting auxiliary temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
32
33
35
37
38
40
42
44
46
52
53
53
53
55
58
59
65
65
66
66
Contents
Chapter 4 — Setting Inlet System Flow Rates . . . . . . . . . . 69
Measuring flow rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using a bubble flow meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Required adapters for measuring flow rates . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the packed inlet flow ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing the source pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the packed inlet flow with septum purge . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the split/splitless capillary inlet flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the split mode flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the splitless mode flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying the gas flow rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Designating gas type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the internal stopwatch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
70
70
72
73
73
74
77
79
85
92
92
93
Chapter 5 — Operating Detector Systems . . . . . . . . . . . . . 95
Displaying detector status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning a detector on or off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monitoring detector output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating detectors using electronic pressure control . . . . . . . . . . . . . . . . . . . . . .
Accessing auxiliary channels C through F . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zeroing the pressure channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting constant pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting pressure ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing pressure ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example of setting pressure ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Verifying pressure ramps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting capillary makeup gas flow rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exceptions to makeup gas flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
If the power fails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Shutting down each day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating the flame ionization detector (FID) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting up the FID for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the FID flow for packed columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the FID flow for capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the makeup gas flow rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning the FID on and off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Igniting the FID flame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
97
98
99
100
101
101
103
104
104
105
106
106
106
109
109
110
111
113
114
119
121
121
Contents
Operating the thermal conductivity detector (TCD) . . . . . . . . . . . . . . . . . . . . . . . .
Setting up the TCD for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the TCD flow for packed columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the TCD flow for capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the TCD carrier gas type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the TCD sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning the TCD on and off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inverting the TCD polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using single-column compensation (SCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating the nitrogen-phosphorus detector (NPD) . . . . . . . . . . . . . . . . . . . . . . . .
Setting up the NPD for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conditioning the NPD active element (bead) . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the NPD active element (bead) power . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the NPD flow for packed columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the NPD flow for capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning the NPD on and off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optimizing the performance of the NPD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating the electron capture detector (ECD) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Requirements for USA owners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Columns and flow rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting up the ECD for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the carrier/makeup gas selection switch . . . . . . . . . . . . . . . . . . . . . . . .
Setting the ECD flow for packed columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the ECD flow for capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing for contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing for leaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Testing for radioactive leaks (the wipe test) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating the flame photometric detector (FAD) . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting up the FPD for operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the FPD flow for packed columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the FPD flow for capillary columns . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning the FPD on and off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Igniting the FPD flame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
122
123
123
124
127
128
128
128
129
134
136
136
138
140
141
145
145
148
148
149
150
150
150
151
151
151
152
153
154
157
159
159
160
160
161
162
166
167
Contents
Chapter 6 — Controlling Signal Output . . . . . . . . . . . . . .
Assigning a signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying or monitoring a signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zeroing signal output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning zero off/on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting signal attenuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning attenuation off/on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Inverting TCD signal polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using instrument network (INET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 7 — Making a Run . . . . . . . . . . . . . . . ...... . .
Starting/stopping a run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
INET start/stop operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the time key. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using single-column compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Displaying column compensation status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Initiating a column compensation run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assigning column compensation data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using instrument network (INET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using timetable events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turning valves on/off during a run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Switching signals during a run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Changing TCD sensitivity during a run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modifying timetable events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 8 — Storing and Loading HP 5890
Series II SetPoints . . . . . . . . . . . . . . . . . . . . . ...
Storing GC setpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading GC setpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
169
171
173
175
176
176
179
180
181
183
184
185
185
188
190
191
192
194
195
196
198
200
201
202
205
206
207
Chapter 9 — Controlling Valves . . . . . . . . . . . . . . . . . . . . .
211
Turning valves on/off manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
213
Contents
Chapter 10 — Using Electronic Pressure Control . . . . . . .
What is electronic pressure control? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using electronic pressure control with inlets (EPC) . . . . . . . . . . . . . . . . . . . . .
Using electronic pressure control with detectors (auxiliary EPC) . . . . . . . . .
Safety shutdown for electronic pressure control. . . . . . . . . . . . . . . . . . . . . . . . . . . .
What happens during electronic pressure control safety shutdown? . . . . . .
Summary table of safety shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting inlet pressure using electronic pressure control . . . . . . . . . . . . . . . . . . . . .
Zeroing the pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting constant flow mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting inlet pressure programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking inlet pressure programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting pressure using auxiliary electronic pressure control . . . . . . . . . . . . . . . . .
How do I access auxiliary electronic pressure control? . . . . . . . . . . . . . . . . . .
Setting constant detector pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting detector pressure programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Suggested ranges for operating auxiliary electronic pressure control . . . . . .
Using electronic pressure control to control gas flow . . . . . . . . . . . . . . . . . . . . . . .
Accessing the flow parameter displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selecting the gas type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the column diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the column length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using vacuum compensation mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using constant flow mode for inlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting mass flow rate for inlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting inlet flow programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the average linear velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Understanding average linear velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calculating outlet flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting the average linear velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Determining the corrected column length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Packed column considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Capillary column considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Optimizing splitless injection using electronic pressure control . . . . . . . . . . . . . .
215
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239
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242
243
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244
245
246
246
248
248
249
249
250
250
250
252
Contents
Operating the gas saver application for the split/splitless inlet . . . . . . . . . . . . . . .
What is the gas saver application? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What are the required settings for operation? . . . . . . . . . . . . . . . . . . . . . . . . . .
How is the gas saver application configured? . . . . . . . . . . . . . . . . . . . . . . . . . . .
How does the gas saver application operate? . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommended flow rates for inlet systems using the gas saver application
Additional benefits of the gas saver application . . . . . . . . . . . . . . . . . . . . . . . . .
Using the external sampler interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Which configuration should I use? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using the external sampler interface with an inlet as a heated zone . . . . . .
Special considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Using valve options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Which valves work best with auxiliary electronic pressure control? . . . . . . .
Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pressure-flow relationships for inlet and auxiliary electronic pressure control
Outlet flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Average linear velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Calculating flow from average linear velocity . . . . . . . . . . . . . . . . . . . . . . . . . .
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
254
254
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256
259
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261
261
270
270
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279
280
281
281
282
285
1
Getting Started
Getting Started
Installation checklist
This checklist will help you get your HP 5890 Series II into operation. All
references are to the HP 5890 Series II Manual Set.
Checklist
Location
Select a location for the instrument.
Site Prep and Installation,
Chapter 1
2. Check the new instrument for damage
in shipment.
Site Prep and Installation,
Chapter 2
3. Make sure everything is present.
Site Prep and Installation,
Chapter 2
4. Place the instrument in position and
make all connections.
Site Prep and Installation,
Chapter 2
5. Turn the instrument on.
Site Prep and Installation,
Chapter 2
6. Install a column.
Operating, Chapter 2
7. Set the inlet system flow rate.
Operating, Chapter 4
8. Set appropriate heated zone
temperatures.
Operating, Chapter 3
9. Set the detector system flow rates.
Operating, Chapter 5
10. Turn the detector on.
Operating, Chapter 5
11. The instrument is now ready to
make a run.
Operating, Chapter 7
1.
10
Getting Started
Daily startup
Daily startup
1. Check that the operating conditions are correct for your analysis.
Make any changes that are needed.
2. Reset the detector sensitivity if you lowered it overnight.
3. If you’re using temperature programming, make a blank run (no
sample) to clean out any septum bleed or carrier gas impurities that
might have accumulated in the column.
4. Start your analysis.
Daily shutdown
1. In most cases, leave the detectors on and at operating temperature.
This will avoid a long equilibration time in the morning. You may want
to reduce the sensitivity particularly with the TCD and NPD detectors,
to prolong their lifetime.
2. Leave the carrier flow on to protect the column(s). For extended
shut-down periods, cool the oven to room temperature and then turn
the carrier flow off.
3. Now is a good time to change the inlet septum if needed. Volatile
material will be baked out overnight. But keep the columns warm so
that the baked-out material doesn’t accumulate on the column. You
can generally expect 1- or 2-days use from a septum, but this is reduced
by high temperatures, many injections, dull or hooked needles, etc. It’s
best to avoid trouble by changing them daily.
Getting Started
Abbreviations
Abbreviations
Analog-to-Digital
Ar/CH 4 Argon/Methane (5% or 10%)
ECD
Electron Capture Detector
EFS
Electronic Flow Sensing
Flame Ionization Detector
FID
General Purpose Valve
GPV
Inside Diameter
ID
INET Instrument Network
Laboratory Automation System
LED
NPD
OD
Light Emitting Diode
Nitrogen-Phosphorus Detector
Outside Diameter
Random Access Memory
Read-Only Memory
ROM
Single-Column Compensation
SCC
S/ECM Sampler/Event Control Module
Thermal Conductivity Detector
TCD
Transistor-Transistor Logic
TTL
Conversions
1 inch (in.) = 2,54 cm
1 psi (pound per square inch) = 6.89 kPa
1 pound (lb) = 0.454 kg
1 µl = 10-6 1 (Liter)
1 pA = 10-12 A (Ampere)
1 mV = 10-3V (Volt)
1 µm = 10-6 m (Meter)
HP 5890 signal output (full scale)
TCD 1 mV, nominal
FID 1
NPD 1
X
1 0- 1 2 A
X
1 0- 1 2 A
ECD 10 Hz. Note that under these conditions, 1 mV (1/1000 of full
scale) is observed at the + IV output.
12
Getting Started
General safety considerations
General safety considerations
Note: The HP 5890 is a Safety Class I instrument, manufactured and
tested according to international safety standards.
There are a number of common sense safety considerations to keep in
mind at all times in using the HP 5890:
●
Hz (Hydrogen) is flammable, and explosive when confined in an
enclosed volume (for example, the oven). In any application using H 2,
turn off the supply at its source when changing columns, performing
service procedures, etc.
When measuring gas flow rates through an FID or NPD, never
measure air and H2 together. They should be measured separately to
minimize explosion hazard.
●
The HP 5890 is supplied with a three-conductor power cord providing a
protective earth ground connection when plugged into a properly wired
receptacle. Proper receptacle grounding must be verified.
●
The oven, inlet, and detector zones may be hot enough to cause burns.
Connected hardware also may be sufficiently hot enough to cause
burns. If necessary, heated areas maybe turned off and allowed to cool.
●
To avoid shock hazard, the power line cord must be disconnected at its
receptacle anytime the rear cover panel must be removed. Also,
connected devices should also be disconnected at their respective line
power receptacles.
●
An ECD, if installed, must have its exhaust vent connected via external
tubing to a proper fume hood.
●
Likewise, for a split/splitless capillary inlet system operated in split
mode, or for a split-only capillary inlet system, the split vent should be
connected via external tubing to a proper fume hood if toxic materials
are analyzed, or if H2 is used as carrier gas.
13
Installing Columns
Installing Columns
The HP 5890 Series II and Series II Plus (hereafter referred to as
HP 5890) provide flexibility in choices among inlets, columns, and
detectors through use of liners and adapters, allowing any standard
column to be used without sacrificing performance. Additional flexibility is
gained through positions of inlets and detectors relative to each other and
through the large internal volume of the oven.
Note: The Series 530 µ columns supplied with the HP 5890 must be
conditioned before use. This is done by establishing a flow of carrier gas at
30 to 60 ml/min through the column while the column is heated at 250° C
for at least 4 hours. See Preventive Maintenance in the HP 5890 Series II
Reference Manual for more information about conditioning columns.
New columns should be conditioned because they often contain volatile
contaminants absorbed from the air. It may also be necessary to condition
a used column that has been stored for some time without end caps or
plugs to exclude air.
This section provides information required for proper column installation:
16
●
Liners and inserts
●
Preparing packed columns
●
Installing packed columns
●
Preparing capillary columns
●
Installing capillary columns
Installing Columns
Preparing fused silica capillary columns
Preparing fused silica capillary columns
Fused silica columns are inherently straight, so no straightening
procedures are necessary. It is important, however, to have fresh ends of
the column, free of burrs, jagged edges, and/or loose particles of column,
stationary phase, and/or material from a sealing ferrule or O-ring.
Therefore, whenever the column must be cut to provide fresh ends, use a
suitable glass scribing tool (HP ceramic column cutter, part number
5181-8836) to first score the column at the point at which it is to be
broken. This is done normally after installing on the column, the column
nuts and ferrule (or O-ring) required for installation.
WARNING
Wear safety glasses to prevent possible eye injury from flying particles
while handling, cutting, or installing glass or fused silica capillary
columns. Also observe caution in handling capillary columns to prevent
skin puncture wounds.
Because of their greater relative rigidity these precautions are especially
important in handling Hewlett-Packard series 530 µ capillary columns.
Installing Columns
Preparing fused silica capillary columns
Preparing Fused Silica Capillary Columns
Installing Columns
Installing split/splitless capillary inserts
Installing split/splitless capillary inserts
A specific inlet insert is required, depending upon the particular sampling
mode. Specific sampling modes include:
● Split,
for major-component analyses
Ž Purged splitless, for trace-component analyses
WARNING
Exercise care! The oven, and/or inlet, or detector fittings maybe hot
enough to cause burns.
Caution
If operating in split mode, carrier gas pressure must be reduced before
opening the inlet. If not done, pressure may blow insert packing out of
the inlet, altering its characteristics. Pressure is reduced at the column
head pressure regulator for the inlet.
1. In handling the insert, avoid contaminating its surface (particularly its
interior).
2. Remove the insert retainer nut. The septum retainer nut need not be
removed from the insert retainer nut assembly.
3. Using tweezers, forceps, or similar tool, remove any insert already in
place.
4. Inspect the new insert to be installed: For a split mode insert, the end
with the mixing chamber and packing is inserted first into the inlet.
5. Place a graphite or silicone O-ring on the insert, about 2 to 3 mm from
its top end.
6. Replace the insert retainer nut, tightening it to firm finger-tightness
to form a leak-free seal. Do not overtighten.
19
Installing Columns
Preparing packed metal columns
Installing Split/Splitless Capillary Inserts
Preparing packed metal columns
Packed metal columns are installed similarly at both the inlet and detector.
To minimize unswept (dead) volume column inside the inlet or detector
fitting, it is recommended that ferrule(s) be preset and locked onto the
column such that the end of the column is approximately flush with the
end of the front ferrule (see the top of the figure on page 22).
20
Installing Columns
Preparing packed metal columns
If not already installed, follow the procedure below to install new
swage-type nut and ferrules. For metal columns with ferrules already
installed and set, proceed to instructions for installing metal columns in
this section.
To insure the correct column position, a spacer maybe made from a piece
of Teflon tubing:
1. According to the column to be installed (1/8 or 1/4 inch), secure an
appropriate new male swage-type fitting in a bench vise.
2. Slide a new, brass, swage-type nut, rear ferrule, and front ferrule onto
a piece of Teflon tubing (1/8 or 1/4 inch). If necessary, use a razor or
sharp knife to cut the end of the tubing to present a flat, smooth end.
3. Fully insert the Teflon tubing, ferrules, and nut into the vise-held
swage-type fitting. Tighten the nut 3/4-turn past finger-tight to set the
ferrules on the tubing. Then remove the assembly from the male
fitting.
4. Using a razor knife, cut off the end of the tubing extending beyond the
front-most ferrule. Insert the piece into the vise-held swage-type
fitting.
This piece of tubing is now a spacer, insuring that when new ferrules
are set onto a column, the column end will be correctly positioned with
respect to the end of the front-most ferrule. The male fitting and
spacer should be kept on hand to be used whenever new ferrules are
being installed on a column.
5. Install a new swage-type nut and ferrule(s) onto the column.
6. Fully insert the column with its nut and ferrules into the vise-held
fitting.
7. First tighten the nut finger-tight. Use a wrench to tighten the column
nut an additional 1- and -1/4 turns for l/4-inch columns, or 3/4-turn for
l/8-inch columns.
Installing Columns
Preparing packed metal columns
8. Unscrew the column nut from the vise-held fittings, and remove the
column. Ferrules should now be set in place on the column, with the
column correctly positioned.
Recommended Location
for Ferrules on Packed
Columns
Recommended
Not Desirable
(May cause problems due to dead volumn)
Making a Teflon Spacer
Exposed Teflon tube to be cut
Cut spacer
Teflon Tubing
Spacer Installed in Fitting
Preparing Packed Metal Columns
22
Installing Columns
Installing 1/4- and l/8-inch metal columns in packed inlets
Installing 1/4- and l/8-inch metal columns in packed inlets
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the inlet base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional l/4-turn.
To install new swage-type nut and ferrules on the column, follow the
procedure Preparing packed metal columns, earlier in this section. For
metal columns with ferrules already installed, continue with step 5.
5. Install the column into the inlet by tightening the column nut,
assuming ferrule(s) are already set (locked) onto the column (see
Preparing packed metal columns in this section). Generally an
additional l/4-turn past finger-tight is sufficient for l/8-inch columns.
For l/4-inch columns, an additional 3/4-turn is usually suffcient.
Use two wrenches in opposition, one on the column nut and the other
on the liner body, to prevent rotation of the liner while tightening the
column nut.
23
Installing Columns
Installing 1/4- and l/8-inch metal columns in packed inlets
l/4-inch Metal
Column, Packed
Inlet
l/8-inch Metal
Column, Packed
Inlet
Inlet Fitting
m
l/4-inch Ferrule
l/8-inch Liner
Installing 1/4 and l/8-inch Metal Columns in Packed Inlets
Installing Columns
Installing l/4-inch glass columns in packed inlets
Installing l/4-inch glass columns in packed inlets
At the inlet end, there must be enough column left empty to prevent an
inserted syringe needle from contacting either the glass wool plug or
column packing (at least 50 mm).
At the detector end, there must be at least a 40-mm empty section to
prevent the bottom end of the jet from touching either column packing or
glass wool plug.
Because they are rigid, l/4-inch packed glass columns must be installed
simultaneously at both the inlet and the detector. The procedure is
identical at either end. For information on detector column installation,
refer to the appropriate section depending on the detector being used.
Glass columns can be installed with either O-rings or nonmetallic ferrules.
For O-ring installation, we recommend using one O-ring with a front
metal ferrule, reversed to provide a flat surface for it to seal against.
Using the figures on the next page as a guide:
1. Assemble a brass nut, reversed metal ferrule, and O-ring onto both
ends of the column.
If desired, an extra O-ring maybe placed on the column before the nut.
This protects the column by preventing the nuts from dropping into
the coiled portion of the column.
2. Insert the column into both the inlet and detector as far as possible.
To clear the floor of the oven, it maybe necessary to start the longer
end of the column into the inlet at a slight angle.
3. Withdraw the column about 1 to 2 mm and tighten both column nuts
finger-tight; the degree to which the nut is tightened further depends
upon the type of ferrule used:
• For O-rings, finger-tight is usually sufficient.
• For Vespel or graphite ferrules, raise the inlet, detector, and oven to
operating temperature, then use a wrench to tighten an additional
l/2-turn. Tighten further as necessary to prevent leakage.
25
Installing Columns
Installing l/4-inch glass columns in packed inlets
Caution
Overtightening the column nut may shatter the column.
l/4-inch Column,
Packed Inlet
Recommended
Alternative
Installation
Methods
Installing l/4-inch Glass Columns in Packed Inlets
26
Installing Columns
Installing capillary columns in packed inlets
Installing capillary columns in packed inlets
Using the figures on page 29 as a guide:
1.
Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Install a glass insert into the liner/adapter.
3. Insert the liner/adapter straight into the inlet as far as possible.
4. Holding the liner/adapter in this position, tighten the nut finger-tight.
5. Use a wrench to tighten the nut an additional l/4-turn.
Hewlett-Packard capillary columns are wound on wire frames and
mount on a pair of brackets that slip into slots at the top of the oven
interior.
The bracket has two positions from which to hang the column wire
frame. Depending upon frame diameter, use the position that best
centers the column in the oven. Column ends should come off the
bottom of the frame, making smooth curves to inlet and detector
fittings. Avoid allowing any section of the column itself to come in
contact with oven interior surfaces.
6. Install on the column, a column nut and ferrule. Note that either a 1. Oor 0.5-mm id graphite ferrule maybe used depending upon column
outer diameter.
Inserting the column through the nut and ferrule may contaminate the
end of the column. Prepare a fresh column end by following the
instructions given in Preparing fused silica capillary columns in this
section.
Installing Columns
Installing capillary columns in packed inlets
7 . Position the column so it extends less than 2.0 mm from the end of the
ferrule and column nut (threaded end). Mark the column at a point
even with the bottom of the nut (hexagonal end). Typewriter
correction fluid is a good marking material.
8.
Insert column, ferrule, and nut straight into the inlet base. While
maintaining the mark on the column so as to be even with the bottom
of the column nut, tighten the nut to finger-tightness, then l/4-turn
more using a wrench.
9 . While holding the spring to the right, slide the capillary liner insulation
cup up over the capillary nut. The insulation at the top of the cup
should fit flush against the roof of the oven.
10. Release the spring into the groove in the inlet liner.
Installing Columns
Installing capillary columns in packed inlets
Capillary Column,
Packed Inlet
Column Hanger
Position
Liner
Marking the
Column Position
1
Paint Mark
Installing Capillary Columns in Packed Inlets
Liner Retainer Nut
Installing Columns
Installing capillary columns in split/splitless capillary inlets
Installing capillary columns in
split/splitless capillary inlets
A specific inlet insert is required depending upon the particular sampling
mode, split or splitless. See Installing split/splitless capillary inlet inserts
in the this chapter, if not already installed.
The following installation procedure assumes that the inlet is prepared
properly to receive the capillary column (e.g., that the correct insert is
already installed).
Hewlett-Packard capillary columns are wound on wire frames and mount
on a pair of brackets that slip into slots at the top of the oven interior.
The bracket has two positions from which to hang the column wire frame.
Depending upon frame diameter, use the position that best centers the
column in the oven. Column ends should come off the bottom of the frame,
making smooth curves to inlet and detector fittings. Avoid allowing any
section of the column itself to come in contact with oven interior surfaces.
Using the figures on the next page as a guide:
1.
Install on the column a column nut and ferrule. Note that either a 1. Oor 0.5-mm id graphite ferrule may be used depending upon column
outer diameter.
Inserting the column through the nut and ferrule may contaminate the
end of the column. Prepare a fresh column end following instructions
given in Preparing fused silica capillary columns in this section.
2. Position the column so it extends approximately 4 to 6 mm from the
end of the ferrule and column nut (threaded end). Mark the column at
a point even with the bottom of the nut (hexagonal end). Typewriter
correction fluid is a good marking material.
3. Insert column, ferrule, and nut straight into the inlet base. While
maintaining the mark on the column so as to be even with the bottom
of the column nut, tighten the nut to finger-tightness, then l/4-turn
more using a wrench.
30
Installing Columns
Installing capillary columns in split/splitless capillay inlets
Capillary Column
Split/Splitless
Capillary Inlet
Column Hanger
Position
Marking the
Column Position
to 6 mm
Capillary Column
Installing Capillary Columns in Split/Splitless Capillary Inlets
Installing Columns
Installing l/4-inch metal columns in FID’s and NPD’s
Installing l/4-inch metal columns in FID’s and NPD’s
Nitrogen-phosphorus detectors: To avoid contamination of the active
element upon receipt, do not remove the seals until ready to connect the
column and operate the detector. Failure to observe this simple procedure
may reduce the collector’s effectiveness or possibly ruin the active element.
To install new swage-type nut and ferrules on the column, follow the
procedure Preparing packed metal columns, earlier in this section. For
metal columns with ferrules already installed, continue.
Using the figures below as a guide:
Install the column into the inlet by tightening the column nut, assuming
ferrule(s) are already set (locked) onto the column (see Preparing packed
metal columns in this chapter). Generally an additional 3/4-turn is usually
sufficient.
l/4-inch Packed Metal
Column, FID/NPD
Inlet Fitting
l/4-inch Column
Installing l/4-inch Metal Columns in an FID and NPD
32
Installing Columns
Installing l/8-inch metal columns in FID’s and NPD’s
Installing l/8-inch metal columns in FID’s and NPD’s
Nitrogen-phosphorus detectors: To avoid contamination of the active
element upon receipt, do not remove the seals until ready to connect the
column and operate the detector. Failure to observe this simple procedure
may reduce the collector’s effectiveness or possibly ruin the active element.
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional l/4-turn.
5. Install the column into the inlet by tightening the column nut,
assuming ferrule(s) are already set (locked) onto the column (see
Preparing packed metal columns in this section). Generally an
additional l/4-turn is usually sufficient.
Use two wrenches in opposition, one on the column nut and the other
on the liner body, to prevent rotation of the liner while tightening the
column nut.
installing Columns
Installing l/8-inch metal columns in FID’s and NPD’s
l/8-inch Packed
Metal Column, FID/NPD
Using Two Wrenches
in Opposition to Tighten
Column Fittings
I
Installing l/8-inch Metal Columns in an FID and NPD
34
Installing Columns
Installing capillary columns in FID’s and NPD’s
Installing capillary columns in FID’s and NPD’s
Nitrogen-phosphorus detectors: To avoid contamination of the active
element upon receipt, do not remove the seals until ready to connect the
column and operate the detector. Failure to observe this simple procedure
may reduce the collector’s effectiveness or possibly ruin the active element.
Assuming that the 0.011-inch capillary jet (HP part no. 19244-80560) is
installed (if not, see Chapter 9, Preventive Maintenance in the HP 5890
Reference Manual), proceed as follows:
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional l/4-turn.
5. Install on the column, a column nut and ferrule. Note that either a 1. Oor 0.5-mm id graphite ferrule may be used depending upon column
outer diameter.
Inserting the column through the nut and ferrule may contaminate the
end of the column. Prepare a fresh column end following instructions
given in Preparing fused silica capillary columns in this chapter.
6. Gently insert the column as far as possible into the detector (about 40
mm) until it bottoms; do not attempt to force it further. Follow it
with the ferrule and column nut.
7. Tighten the nut finger-tight, withdraw the column approximately
1 mm, and then tighten the nut an additional l/4-turn with a wrench.
8. Leak-test the installation at the column nut, both at ambient
temperature and with the oven, inlet(s), and detector(s) at operating
temperatures. If necessary, tighten fitting(s) further only enough to
stop leakage.
35
Installing Columns
Installing capillary columns in FID’s and NPD’s
Caution
Leak-detection fluids often leave contaminating residues. After each
application, the area checked should be rinsed with CH3OH (methanol)
and allowed to dry.
Capillary Column, FID/NPD
Column Hanger
Position
Installing Capillary Columns in FID and NPD
Installing Columns
Installing an l/8-inch metal column in a thermal conductivity detector
Installing an l/8-inch metal column
in a thermal conductivity detector
To install new swage-type nut and ferrules on the column, follow the
procedure Preparing packed metal columns, earlier in this chapter. For
columns with ferrules already installed, continue.
Using the figure below as a guide:
Install the column into the inlet by tightening the column nut, assuming
the ferrule(s) are already set onto the column. An additional l/4-turn is
usually sufficient.
l/8-inch Packed
Metal Column, TCD
Installing a l/8-inch Metal Column in a Thermal Conductivity Detector
37
Installing Columns
Installing a capillary column in a thermal conductivity detector
Installing a capillary column in a
thermal conductivity detector
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional l/4-turn.
5. Install on the column, a column nut and ferrule. Note that either a 1. Oor 0.5-mm id graphite ferrule maybe used depending upon column
outer diameter.
Inserting the column through the nut and ferrule may contaminate the
end of the column. Prepare a fresh column end following instructions
given in Preparing fused silica capillary columns in this chapter.
6. Gently insert the column as far as possible into the detector until it
bottoms; do not attempt to force it further. Follow it with the ferrule
and column nut.
7. Tighten the nut finger-tight, withdraw the column approximately
1 mm, and then tighten the nut an additional l/4-turn with a wrench.
8. Leak-test the installation at the column nut, both at ambient
temperature and with the oven, inlet(s), and detector(s) at operating
temperatures. If necessary, tighten fitting(s) further only enough to
stop leakage.
Caution
38
Leak-detection fluids often leave contaminating residues. After each
application, the area checked should be rinsed with CH3OH (methanol)
and allowed to dry.
Installing Columns
Installing a capillary column in a thermal conductivity detector
Capillary Column
With Makeup Gas, TCD
Column Hanger
Position
Capillary Column
Installing a Capillary Column in a Thermal Conductivity Detector
Installing Columns
Installing a l/4-inch glass column in an electron capture detector
Installing a l/4-inch glass column in
an electron capture detector
Because they are rigid, l/4-inch packed glass columns must be installed
simultaneously at both the inlet and the detector. The procedure is
identical at either end. For information on inlet column installation, refer
to the appropriate chapter depending on the inlet being used.
Glass columns can be installed with either O-rings or nonmetallic ferrules.
For O-ring installation, we recommend using one O-ring with a front
metal ferrule, reversed to provide a flat surface for it to seal against.
Using the figures on the next page as a guide:
1. Assemble a brass nut, reversed metal ferrule, and O-ring onto both
ends of the column.
If desired, an extra O-ring maybe placed on the column before the nut.
This protects the column by preventing, the nuts from dropping into
the coiled portion of the column.
2. Insert the column into both the inlet and detector as far as possible.
To clear the floor of the oven, it may be necessary to start the longer
end of the column into the inlet at a slight angle.
3. Withdraw the column about 1 to 2 mm and tighten both column nuts
finger-tight; the degree to which the nut is tightened further depends
upon the type of ferrule used:
• For O-rings, finger-tight is usually sufficient.
• For Vespel or graphite ferrules, raise the inlet, detector, and oven to
operating temperature, then use a wrench to tighten an additional
l/2-turn. Tighten further as necessary to prevent leakage.
Caution
40
Overtightening the column nut may shatter the column.
Installing Columns
Installing a l/4-inch glass column in an electron capture detector
l/4-inch Packed Glass
Column, ECD
Recommended
l/4-inch Packed Glass
Columns, Alternative
Installation Methods
Silicone O-ring
Graphite, Vespel,or
Graphitized Vespel Ferrule
Installing a l/4-inch Glass Column in an Electron Capture Detector
Installing Columns
Installing a capillary column in an electron capture detector
Installing a capillary column in an
electron capture detector
Using the figures on the next page as a guide:
1. Remove the cap of the makeup gas adapter.
2. Install a fused silica liner in the bottom half of the adapter.
3. Replace the cap of the makeup gas adapter. Tighten the cap
hand-tight.
4. Insert the ECD adapter straight into the detector as far as possible and
tighten the nut finger-tight.
5. Use a wrench to tighten the nut an additional l/4-turn.
6. Install on the column a column nut and ferrule. Note that either a 1. Oor 0.5-mm id graphite ferrule may be used depending upon column
outer diameter.
Inserting the column through the nut and ferrule may contaminate the
end of the column. Prepare a fresh column end following instructions
given in Preparing fused silica capillary columns in this chapter.
7. Measure 75 mm from the end of the column and mark the column.
Typewriter correction fluid is a good marking material. Gently insert
the column into the detector followed by the ferrule and column nut.
Tighten the nut finger-tight. Position the column so the 75-mm mark
is even with the end of the column nut. Tighten the nut an additional
l/4-turn with a wrench.
42
Installing Columns
Installing a capillary column in an electron capture detector
Column Hanger Position
Capillary Column
with Makeup Gas, ECD
Ferrule
Capillary Column Nut
I
Installing a Capillary Column in an Electron Capture Detector
43
Installing Columns
Installing an l/8-inch metal column in a flame photometric detector
Installing an l/8-inch metal column
in a flame photometric detector
To install new swage-type nut and ferrules on the column, follow the
procedure Preparing packed metal columns, earlier in this chapter. For
columns with ferrules already installed, continue.
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the liner/adapter.
2. Insert the adapter straight into the detector base as far as possible.
3. Holding the adapter in this position, tighten the nut finger-tight.
4. Use a wrench to tighten the nut an additional l/4-turn.
5. Install the column into the inlet by tightening the column nut
assuming ferrule(s) are already set (locked) onto the column (see
Preparing packed metal columns in this chapter). An additional
l/4-turn is usually sufficient.
Use two wrenches in opposition, one on the column nut and the other
on the liner body, to prevent rotation of the liner while tightening the
column nut.
44
Installing Columns
Installing an l/8-inch metal column in a flame photometric detector
Using Two Wrenches in
Opposition to Tighten
Column Fittings
l/8-inch Packed Metal
Column, FPD
l/4-inch Ferrule
l/4-inch Nut
I
l/8-inch Liner
Installing an l/8-inch Metal Column in a Flame Photometric Detector
Installing Columns
Installing a capillary column in a flame photometric detector
Installing a capillary column in a
flame photometric detector
Using the figures on the next page as a guide:
1. Assemble a brass nut and graphite ferrule onto the FPD capillary
column adapter.
2. Insert the FPD adapter straight into the detector as far as possible and
tighten the nut finger-tight.
3. Use a wrench to tighten the nut an additional l/4-turn.
4. Install on the column a column nut and ferrule. Note that either a 1. Oor 0.5-mm id graphite ferrule may be used depending upon column
outer diameter.
Inserting the column through the nut and ferrule may contaminate the
end of the column. Prepare a fresh column end following instructions
given in Preparing fused silica capillary columns in this chapter.
5. Measure 162 mm from the end of the column and mark the column.
Typewriter correction fluid is a good marking material. Gently insert
the column into the detector followed by the ferrule and column nut.
Tighten the nut finger-tight. Position the column so the 162-mm mark
is even with the end of the column nut. Tighten the nut an additional
l/4-turn with a wrench.
This height may be optimized higher or lower depending on sample
type and detector flow rates. If the column is too high, it can be
exposed to the detector flame. If the column is too low, the sample can
be exposed to some hot stainless steel which can result in slight peak
tailing.
46
Installing Columns
Installing a capillary column in a flame photometric detector
Capillary Column, FPD
T
162 mm
1
Paint Mark
Installing a Capillary Column in a Flame Photometric Detector
47
3
Setting Heated Zone
Temperatures
Setting Heated Zone Temperatures
Oven temperature, and temperatures of up to five separate heated zones
(detectors, inlets, and/or heated valves), are controlled through keys
shown.
TEMPERATURE CONTROL KEYS
Oven Control
In these cases, both current setpoint value and current monitored value
are displayed by pressing the appropriate temperature control key. For
example, the next figure shows typical displays obtained by pressing the
OVEN TEMP
Setting Heated Zone Temperatures
ACTUAL
SETPOINT
Typical Display, Setpoint And Current Value
Note that the ACTUAL value is a measured quantity, while the SETPOINT
value is user-defined: In this example, the setpoint value for oven
temperature might recently have been changed from 250 to 350° C, and the
oven is now heating to the new setpoint. Given sufficient time for
equilibration, ACTUAL and SETPOINT values become equal.
used in certain specific key sequences:
oven, and/or heated zones, without losing their current setpoint values.
parameters for the third ramp.
51
Setting Heated Zone Temperatures
Operating limits for heated zones
Operating limits for heated zones
Valid Setpoint Ranges For Temperature Control Keys
Key
Valid
Setpoint Range
In
Increments of
Function
–80 to 450
1“c
Oven Control
–80 to 450
1“c
Oven Control
0 to 650.00
0.01 minute
Oven Control
0 to 70
0.1 /minute
Oven Control
–80 to 450
1“c
Oven Control
0 to 650.00
0.01 minute
Oven Control
70 to 450
1“c
Oven Control
0 to 200.00
0.01 minute
Oven Control
0 to 400
1“c
Zone Control
0 to 400
1“c
Zone Control
0 to 400’
1“c
Zone Control
o to 400’
1“c
Zone Control
o to 400
1“c
Zone Control
*The valid setpoint range for a flame ionization detector is O to 450°C.
Setting Heated Zone Temperatures
Setting oven temperatures
Setting oven temperatures
Oven temperature may be controlled anywhere within the range of –80°C
(with cryogenic cooling using liquid N2) through 4500C in increments of
0
1 c.
Oven temperature control keys include:
OVEN TEMP
To enter a constant temperature for the oven
EQUIB TIME
To enter a time for oven temperature to equilibrate
whenever oven temperature is modified
(Equilibration time begins when the actual oven temperature comes within 1°C of the oven temperature setting.)
53
Setting Heated Zone Temperatures
Setting oven temperatures
Setting the oven maximum to 350°C
The maximum temperature the oven can be set to is 350°C.
The HP 5890 SERIES II verifies oven setpoints as they are entered; an
appropriate message is displayed when an entered setpoint is inconsistent
with a previously defined setpoint.
In this case, an oven temperature greater then 3500C was attempted while
the OVEN MAX is set to 350°C.
54
Setting Heated Zone Temperatures
Using cryogenic oven cooling
Using cryogenic oven cooling
Oven temperature may be controlled below ambient when a cryogenic
valve is present.
Cryogenic control setpoints are:
CRYO ON
To enable subambient control of the oven
CRYO OFF
To disable subambient cooling of the oven; the default
state for the cryogenic valve is OFF.
CRYO BLAST ON
To enable very fast cool-downtime after a run
CRYO BLAST OFF
To disable very fast cooling of the oven
AMBIENT
Sets optimal temperature control for efficient use of cryogenic
fluid. (The default temperature setting is 250C.)
CRYO FAULT ON/OFF
A fault occurs when the oven does not reach set temperature after
17 minutes of continuous cryo operation. The oven turns off and
WARN:OVEN SHUT OFF is displayed. Turning Cryo Fault OFF will
disable this feature.
CRYO TIMEOUT XXX MIN
A cryo timeout occurs when a run does not start within a specified
time (1 O to 120 minutes) after the oven equilibrates. Turning Cryo
Timeout OFF will disable this feature. Default is ON for 30 minutes.
When on, the cryogenic valve (if installed) operates automatically to obtain
an oven temperature when there is demand for coolant to be supplied to
the oven.
55
Setting Heated Zone Temperatures
Using cryogenic oven cooling
When cryogenic cooling is not needed, cryogenic valve operation must be
turned off. If this is not done, proper oven temperature control may not
be possible, particularly at temperatures near ambient.
The Cryo Blast feature can operate together with or independently of Cryo
On/Off. Cryo Blast cools the oven faster after a run than it normally
would under normal cryogenic operation. This allows the HP 5890 to
become ready for the next run earlier than it would without cryo blast on.
This feature is useful when maximum sample throughput is necessary.
related to cryogenic valve operation. To turn cryogenic operation on/off
and cryogenic blast on/off, the following key sequence is used:
To turn Cryo Blast operation on or off, the following key sequence is used:
An example key sequence to change the ambient temperature setting to
23° C is:
Setting Heated Zone Temperatures
Using cryogenic oven cooling
Ambient temperature is setable to allow fine tuning of cryogenic operation.
The default setting is 25°C and for most applications need not be changed.
For more information about adjusting the ambient cryogenic setting, see
the HP 5890 SERIES II Reference Manual.
The following figure shows displays associated with disabling/enabling
automatic cryogenic valve operation.
ACTUAL
I
CRYO ON
I
CRYO OFF
I
CRYO FAULT ON
I
ACTUAL
SETPOINT
ACTUAL
SETPOINT
ACTUAL
I
Displays, Cryogenic Valve Operation
SETPOINT
CRYO TIMEOUT 20 Min
I
SETPOINT
Setting Heated Zone Temperatures
Programming oven temperatures
Programmi ng oven temperatures
The oven temperature may be programmed from an initial temperature to
a final temperature (in any combination of heating or cooling) using up to
three ramps during a run.
Oven temperature programming keys include:
INIT VALUE
The starting temperature of a temperature programmed run.
This is also the temperature the oven returns to at the end of a
temperature programmed run.
INIT TIME
The length of time the oven will stay at the starting temperature
after a programmed run has begun.
RATE
Controls the rate at which the oven will be heated or cooled in
degrees C/min. A tempeture-programming rate of 0 halts
further programming.
I
FINAL VALUE
FINAL TIME
Temperature the oven will reach at the end of a heating or
cooling temperature-programmed run.
The length of time the oven temperature will be held at the final
temperature of a temperature-programmed run.
Total elapsed time for a run cannot exceed 650 minutes. At 650 minutes,
the run terminates and oven temperature returns to the initial oven
temperature. In isothermal operation (RATE = O), the instrument
internally sets run time to the maximum of 650 minutes.
58
Setting Heated Zone Temperatures
Programming oven temperatures
Examples
A single-ramp temperature program
Programming oven temperature from 100°C to 200°C at I0°C/min.
Current oven temp = 1000C,
INIT VALUE
INIT TIME
RATE
FINAL VALUE
FINAL TIME
100
2
10
200
1
Single-Ramp
Temperature Program
FINAL
VALUE
RATE
INIT
VALUE
INIT
\
\ EQUIB
\ TIME Oven Ready
for Next Run
Run Terminates
Automatically
Example setpoints for a single-ramp temperature program
59
Setting Heated Zone Temperatures
Programming oven temperatures
A two-ramp temperature program
Oven temperature will be held at 100° C for 2 minutes, then program from
1000C to 200°C at I0° C/min for the first ramp.
Oven temperature will be held at 200° C for 2 minutes, then program from
2000C to 2500 C at 5°C/min for the second ramp.
1ST RAMP
100
2
10
200
2
INIT VALUE
INIT TIME
RATE
FINAL VALUE
FINAL TIME
I
I
2ND RAMP
RATE A
FINAL VALUE
FINAL TIME
5
250
1
Two-Ramp
Temperature Program
FINAL
VALUE A
RATE A
FINAL
VALUE
\
\
\
RATE
INIT
VALUE
INIT
for Next Run
Run Terminates
Automatically
Example setpoints for a two ramp oven program
Setting Heated Zone Temperatures
Programming oven temperatures
A three-ramp temperature program
Oven temperature will be held at 100” C for 1 minute, then program from
1000C to 2000C at 10°C/min for the first ramp.
Oven temperature will be held at 2000C for 2 minutes, then program from
2000C to 250°C at 10°C/min for the second ramp.
Oven temperature will be held at 250° C for 2 minutes, then program from
2500C to 3000C at 10°C/min for the third ramp. Oven temperature will
be held at 300°C for 1 minute before returning to the initial starting
temperature of 1000C.
Setting Heated Zone Temperatures
Programming oven temperatures
1ST RAMP
INIT VALUE
INIIT TIME
RATE
FINAL VALUE
FINAL TIME
2ND RAMP
3RD RAMP
100
1
10
200
2
RATE A
FINAL VALUE
FINAL TIME
RATE B
FINAL VALUE
FINAL TIME
10
250
2
Three-Ramp
Temperature Program
Run Terminates
Automatically
Example setpoints for a three-ramp oven program
62
10
300
1
Setting Heated Zone Temperatures
Programming oven temperatures
A three-ramp temperature program (with a controlled cool-down step)
Oven temperature will be held at 100 0C for 1 minute, then program from
1000C to 2000C at 10° C/min for the first ramp.
Oven temperature will be held at 200 0C for 2 minutes, then cool
(controlled) from 200°C to 150°C for the second ramp.
Oven temperature will be held at 150 0C for 1 minute, then program from
1500C to 2500C at I0°C/min for the third ramp. Oven temperature will
be held at 2500C for 2 minutes before returning to the initial starting
temperature of 1000C.
Setting Heated Zone Temperatures
Programming oven temperatures
1ST RAMP
INIT VALUE
INIT TIME
RATE
FINAL VALUE
FINAL TIME
100
1
10
200
2
2ND RAMP
RATE A
FINAL VALUE
FINAL TIME
3RD RAMP
5
150
1
RATE B
FINAL VALUE
FINAL TIME
10
250
2
Three-Ramp
Temperature Program
with a Cooling Step
FINAL
FINAL
Cool-down
(controlled)
for Next Run
Run Terminates
Automatically
Example setpoint conditions for a three-ramp oven program
64
Setting Heated Zone Temperatures
Setting inlet and detector temperatures
Setting inlet and detector temperatures
Inlet and detector temperatures may be controlled anywhere from room
temperature to 400° C.
Inlet and detector temperature control keys include:
INJ A TEMP
To set temperature for the inlet in the A position
INJ B TEMP
To set temperature for the inlet in the B position
DET A TEMP
To set temperature for the detector in the A position
DET B TEMP
To set temperature for the detector in the B position
Displaying inlet and detector temperature
An inlet or detector is switched on or off with key sequences:
Setting Heated Zone Temperatures
Setting auxiliary temperatures
The inlet or detector is also switched on by entering a new setpoint value;
the new value replaces OFF or the previous value.
Example
Setting inlet temperature to 2000C
Current inlet temp = OFF
Display =
INJ A TEMP
38
OFF
1
Setting detector temperature to 2000C
Current detector temp = OFF
Setting auxiliary temperatures
Any of these keys may control an auxiliary heated zone
depending upon the instrument configuration.
Instructions are provided in a separate envelope when a temperature
control key has been assigned to a heated zone other than the zone it
identifies.
—
66
Setting Heated Zone Temperatures
Setting auxiliary temperatures
As an example, to set the AUX TEMP heated zone to 100 0C,
Heated Zone Temperature Control
Key Assignments
I
I
Instrument Rear
4
Setting Inlet System
Flow Rates
Setting Inlet System Flow Rates
This chapter provides operating information for the following HP 5890
inlet systems:
• Septum-purged packed column inlet
●
Split/splitless capillary inlet
Operating information for the Programmable Cool On-Column Inlet is
provided in a separate manual included with the HP 5890.
Measuring flow rates
Use a bubble flow meter to initialize all flows for the first time and to
check them whenever the system is changed in some way.
Bubble Flow Meter for Measuring Flow Rates
Using a bubble flow meter
A bubble flow meter with rate ranges of 1, 10, and 100 ml/min is suitable
for measuring both low flow rates (such as carrier gases) and higher flOW
rates (such as air for an FID).
A bubble flow meter is a very basic, reliable tool for measuring gas flow. It
creates a bubble meniscus across a tube through which the gas is flowing.
The meniscus acts as a barrier and its motion reflects the speed of the gas
through the tube. Most bubble flow meters have sections of different
diameters so they can measure a wide range of flows conveniently.
70
Setting Inlet System Flow Rates
Measuring flow rates
1. Attach one end of the bubble flow meter adapter to the flexible
gas-inlet line of the bubble flow meter.
2. Attach the other end of the adapter to the detector outlet exhaust vent
or other vent through which you will measure flow.
3. Fill the bulb of the bubble flow meter with soapy water or leak
detection fluid (such as Snoop®).
4. Prepare the built-in stopwatch on the keyboard using the following
keystrokes on its keypad:
The display on the oven module now displays zeroes for the time (t)
and the reciprocal time (l/t).
5.
While holding the bubble flow meter vertically squeeze and release the
bulb to create a meniscus in the bubble flow meter.
6.
lowest line in the bubble flow meter.
‘i’.
upper line in one of the tube sections.
8.
Calculate the flow rate in ml/min:
. If you stopped the meniscus at the first line, the flow rate is
numerically equivalent to the reciprocal time reading displayed on
the oven module.
● If
you stopped the meniscus at the second line, the flow rate is
numerically equivalent to 10 times the reciprocal time reading
displayed on the oven module.
● If
you stopped the meniscus at the third line, the flow rate is
numerically equivalent to 100 times the reciprocal time reading
displayed on the oven module.
9.
flow.
10. Start the makeup gas flow by turning the Aux Gas knob on the
upper-left portion of the oven front counterclockwise until the valve is
in the open position.
Setting Inlet System Flow Rates
Measuring flow rates
11. Measure the total gas flow by repeating steps 5 through 8.
12. If the flow is not correct:
• Wait at least 2 minutes for the flow through the system to stabilize.
● Repeat
the above procedure as necessary.
Note: If you use an FID, TCD, or NPD, use a small screwdriver to
adjust the variable restrictor at the center of the Aux Gas knob as
necessary.
Required adapters for measuring flow rates
In general, inlet system, or column, flow rates are measured at detector
exhaust vents. Septum purge and split flow rates for capillary inlet
systems are measured at vents located on the front of the flow panel. A
rubber adapter tube attaches directly to an NPD, ECD, or TCD exhaust
vent tube.
A special flow-measuring adapter is supplied for an FID. Attach a bubble
flow meter to the FID flow-measuring adapter and insert it into the detector
exhaust vent as far as possible. You may feel initial resistance as the
adapter’s O-ring is forced into the detector exhaust vent. Twist and push
the adapter during insertion to ensure that the O-ring forms a good seal.
WARNING
To minimize the risk of explosion, never measure air and H2 together.
Measure them separately.
NPD, TCD, and ECD Use
Required Adapters for Measuring Gas Flow Rates
72
Setting Inlet System Flow Rates
Changing the packed inlet flow ranges
Changing the packed inlet flow ranges
You may want to change the flow range of your inlet for a number of
reasons. For example, if you are using flows in the lowest 20 percent of a
flow restrictor’s range, the retention times of your analysis might wander.
By changing from a flow of 20 ml/min with a flow restriction range of O to
110 ml/min to one with a range of O to 20 ml/min, you can eliminate this
problem.
You can change the flow ranges in packed inlets by either:
● Changing
the source pressure, or
• Changing the flow restrictor in the flow controller. For instructions on
changing the flow restrictor, see the section on Changing the flow
restrictor in the Site Prep/Installation Manual.
Changing the source pressure
You can increase the upper limit of flow from a flow controller by
increasing the source pressure. The following table lists the maximum
flows for the standard flow controller for a packed inlet with a O to 20
ml/min flow restrictor at five pressures. For maximum H2 flows, read from
the Helium Flow column.
Source Pressure
(psi)
Nitrogen Flow
(ml/min)
Helium Flow
(ml/min)
40
50
60
70
80
20
24
28
32
36
21
25
28
32
35
Setting Inlet System Flow Rates
Setting the packed inlet flow with septum purge
Setting the packed inlet flow with septum purge
Use the following steps to set the packed inlet flow:
1.
Set the oven and heated zone temperatures to the desired operating
values.
Note: Never heat the column until the flow rates are set.
2.
Turn off the detector (particularly an NPD or TCD), if it is not off
already until you set the carrier flow rate.
Note: The detector signal can be assigned to an appropriate output
channel.
3. Set the carrier source pressure to at least 275 kPa (40 psi) to ensure
proper operation for most applications.
Note: Carrier source pressure must beat least 105 kPa (15 psi) greater
than the maximum column head pressure.
4.
Turn off any other support gases to the detector (such as H2, air,
reference flow, or capillary makeup gas) to permit independent
measurement of column flow rate.
5. Your inlet is equipped with either manual or electronic flow control.
Set the column head pressure according to the appropriate section
below.
Manual flow control:
Turn the mass flow controller counterclockwise as necessary to obtain
the desired flow rate, as measured with a bubble flow meter at the
detector exhaust vent.
74
Setting Inlet System Flow Rates
Setting the packed inlet flow with septum purge
Electronic pressure control:
a. Select the pressure units you would like to use.
number of the corresponding unit you want to use:
b. The example below sets Inlet B (Injector B) pressure to 10 psi. Use
the example to set the pressure you have selected.
ACTUAL
I
EPP B
10.0
SETPOINT
10.0
I
The GC display looks like this
Note: To keep the pressure constant through an oven ramp program,
see Chapter 10, Using Electronic Pressure Control.
6. Check the septum purge flow rate:
The septum purge flow is freed. Although it is not adjustable, you
should check the flow. Do not cap off the flow from the purge vent.
Carrier Gas Type
Approx. Flow
H2
1.2–2.2 ml/min
He
N2
Argon/Methane
1.0–1.8
0.6–1.2
0.5–1.1
7. Recheck the column flow rate and adjust as necessary.
Setting Inlet System Flow Rates
Setting the packed inlet flow with septum purge
Manual Pressure
Control
Pressure Gauge
Mass Flow Controller
Septum Purge Vent
Electronic Pressure
Control
Septum Purge Vent
Flow Panels Controlling Purged Packed Inlet
76
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Setting the split/splitless capillary inlet flow
Set the linear velocity through the column when using capillary columns.
Linear velocity is controlled by pressure at the head of the column.
Pressure required to obtain a particular velocity depends primarily upon
the bore (id) of the column, length of the column, and oven temperature.
Hewlett-Packard fused-silica capillary columns are categorized according
to their bores. The table below lists the initial pressures for some capillary
column bores and lengths.
The high pressure in each range is recommended as a starting point for
most analyses and yields a good compromise between efficiency and speed
of analysis. The following sections provide procedures to adjust head
pressure to obtain any desired flow velocity through the column.
Suggested Initial Head Pressures for Capillary Columns
Column Column
id (mm) Length (m)
0.20
0.20
0.20
Helium Carrier Gas
kPa
psi
Hydrogen Carrier Gas
kPa
psi
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Manual Pressure
Control
Pressure Gauge
Column Head Pressure Control
Total Flow Controller
Split Vent
Septum Purge Vent
Electronic Pressure
Control
Total Flow Controller
Split Vent
Flow Panels Controlling Split/Splitless Inlet
Septum Purge Vent
Setting Inlet System Flow Rates
Setting the spIit/splitless capillary inlet flow
Setting the split mode flow
WARNING
When performing split sampling and using hazardous chemicals and/or
H 2 carrier gas, vent effluent from the split vent and septum purge vent
to a fume hood or appropriate chemical trap.
To ensure proper operation, make sure the carrier source pressure is at
least 105 kPa (15 psi) greater than the selected column head pressure.
1. Use the following steps to set the initial column head pressure:
a. Set the column head pressure to O:
(or
b. Increase the total flow control as necessary to obtain 100 ml/min
measured at the split vent.
c.
Increase the column head pressure to obtain the selected pressure.
Your inlet is equipped with either manual or electronic pressure
control. Set the column head pressure according to the appropriate
instructions below.
d. Set the oven and heated zone temperatures to the desired operating
values. Make sure the detector is turned on and its output signal is
assigned to an appropriate channel (see Chapter 6, Controlling the
Signal Output).
Manual flow control:
Turn the mass flow controller counterclockwise to establish flow.
This will cause the gauge pressure to increase.
Electronic pressure control:
a. Select the pressure units you would like to use.
number of the corresponding unit you want to use:
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
b. The example below sets Inlet B (Injector B) pressure to 10 psi. Use
the example to set the pressure you have selected.
ACTUAL
I
EPP B
10.0
SETPOINT
10.0
I
The GC display looks like this
Note: To keep the pressure constant through an oven ramp
program, see Chapter 10, Using Electronic Pressure Control.
2.
Check the septum purge flow rate.
Excess carrier gas is vented through the septum purge vent. Although
the septum purge vent is not adjustable, you should check the flow. Do
not cap off the flow from the purge vent.
Carrier Gas Type
Approx. Flow
H2
3.5-6.0 ml/min
He
1.5-3.5 ml/min
N2
1.5-3.5 ml/min
Argon/Methane
1.5-3.5 ml/min
3. Set the linear velocity:
Using the timer feature (see Using the Internal Stopwatch in this
chapter) and repeated injection of an unretained component, adjust the
column head pressure as necessary to obtain the expected retention
time for the desired linear velocity
Linear velocity through the column is measured by injecting a sample
containing an unretained component (typically CH 4 or air).
The observed retention time for the unretained component is
compared to an expected retention time (tr) calculated from the desired
linear flow velocity (p.) and the length of the column:
80
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
4.
Calculate the volumetric flow rate, if desired:
Use the following formula to simplify the calculation of volumetric flow
through a capillary column:
where
D is column internal diameter
L is column length
tr is retention time (min) of an unretained component,
assuming the desired linear velocity (p.) has been obtained
This calculation becomes less accurate as pressure and gas compression
are increased.
The table below lists values of 0.785x D2L for capillary column bores
and lengths:
Values of 0.785x D2L for Various Capillary Column Bores and Lengths
Nominal Length (m)
Nominal
id (mm)
5.
12
25
50
0.20
0.377
0.785
1.57
0.25
0.589
1.22
2.45
0.32
0.965
2.01
4.02
0.53
2.65
5.51
11.0
0.75
5.30
11.0
22.1
Use a bubble flow meter connected at the detector exhaust vent to
verify the calculated volumetric flow rate through the column. (For
bubble flow meter operating instructions, see Using a bubble flow
meter earlier in this chapter.) Turn off any other gases to the detector,
such as makeup and/or support gases.
81
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
6. Use the following steps to verify that the inlet split flow is currently
passing through the inlet insert and will remain so throughout runs
that are made in split sampling mode:
a. Display the current inlet split vent status:
Press:
PURGE/VALVE
inlet insert.
b. Display the time at which the split flow will be halted:
Press: c
c.
PURGE/VALVE
Display the time at which the split flow will be restored:
Press:
d. Alternatively, set both times to 0.00 and turn on Purge A (or B):
ACTUAL
I
PURGE VALVE A TIME ON
SETPOINT
I
7. Use the following steps to obtain the desired split ratio:
a. Measure the flow rate at the split vent using a bubble flow meter.
For bubble flow meter operating instructions, see Using a bubble
f!ow meter in this chapter
b. Adjust the total flow control as necessary to obtain the flow rate
required for the desired split ratio.
c.
Choose the split ratio appropriate for the analysis.
From the definition for the split ratio, use the following
relationship to determine the flow rate to be expected at the split
vent for any desired split ratio:
Split Vent Flow Rate (ml/min) =
Volumetric Column Flow Rate (ml/min) x (Desired Split Ratio - 1)
82
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Total Flow
Electronic Pressure Controlled
through Keyboard Entry
To Detector
This example shows a 100:1 split ratio
100 ml/min Split Flow
1 ml/min Column Flow
Split Flow Diagram for Electronic Pressure Control
Setting Inlet System Flow Rates
Setting the split/spIitless capillary inlet flow
Total Flow
Control
Septum
Purge
Control
Capillary Inlet
104 ml/min
I
L
ml/min
l-l
To Detector
This example shows a 100:1 split ratio
100 ml/min Split Flow
1 ml/min Column Flow
Split Flow Diagram for Manual Pressure Control
84
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Setting the splitless mode flow
WARNING
When performing splitless sampling and using hazardous chemicals
and/or H2 carrier gas, vent effluent from the split vent and septum
purge vent to a fume hood or appropriate chemical trap.
To ensure proper operation, make sure the carrier source pressure is at
least 105 kPa (15 psi) greater than the selected column head pressure.
Use these steps to set the splitless mode flow. This procedure assumes that
detector gases are connected, the system is leak-free, and the column and
insert are properly installed.
1. Use the following steps to set the initial column head pressure:
a. Set the column head pressure and total flow controls to O.
Sets the EPC inlets to O
b. Increase the total flow control as necessary to obtain 50 ml/min
measured at the inlet vent.
c.
Increase the column head pressure to obtain the selected pressure.
Your inlet is equipped with either manual or electronic pressure
control. Set the column head pressure according to the following
instructions for your inlet.
d. Set the oven and heated zone temperatures to the desired operating
values. Make sure the detector is turned on and its output signal is
assigned to an appropriate channel (see Chapter 6, Controlling
Signal Output).
Manual flow control:
Turn the mass flow controller counterclockwise to establish flow. This
will cause the gauge pressure to increase.
85
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Electronic pressure control:
a.
number of the corresponding unit you want to use:
b. The example below sets Inlet B (Injector B) pressure to 10 psi. Use
the example to set the pressure you have selected.
c.
Press:
ACTUAL
I
EPP B
10.0
SETPOINT
10.0
I
The GC display looks like this
Note: To keep the pressure constant through an oven ramp
program, see Chapter 10, Using Electronic Pressure Control.
2. Check the septum purge flow rate if you have an EPC system.
Excess carrier gas is vented through the septum purge vent. Although
the septum purge vent is not adjustable, you should check the flow. Do
not cap off the flow from the purge vent.
Carrier Gas Type
Approx. Flow
H2
He
N2
Argon/Methane
3.5-6.0 ml/min
1.5-3.5 mi/min
1.5-3.5 ml/min
1.5-3.5 ml/min
3. Set the linear velocity:
Use the timer feature (see Using the internal stopwatch in this chapter)
and make repeated injections of an unretained component. Then adjust
the column head pressure as necessary to obtain the expected retention
time for the desired linear velocity,
86
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Linear velocity through the column is measured by injecting a sample
containing an unretained component (typically CH4 or air).
The observed retention time for the unretained component is
compared to an expected retention time (t r) calculated from the desired
linear flow velocity (µ) and the length of the column:
4. Use the following steps to set the splitless injection timetable:
Splitless injection is made possible by redirecting the inlet purge flow
away from the inlet insert at the time of injection. After injection,
sufficient time is allowed for solvent and sample components to
reconcentrate at the head of the column. Then by redirecting the purge
flow back through the insert, solvent vapor within the inlet insert is
purged.
There are two purge control channels, one for inlet A and one for
inlet B.
a. To redirect the purge flow away from the column to allow for a
splitless injection:
Press:
Note: Flow through the insert at this point passes only through the
column.
b. To restore the inlet purge flow:
Press: c
PURGE/VALVE
Manual purge switching:
Use the keyboard to switch the splitless solenoid valve on or off
manually. Attempting to switch the valve on (or off) when it is already
on (or off) has no effect.
The figure below shows typical displays for current valve status and for
verifying the timed events table to switch the valve automatically
during a run.
87
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
ACTUAL
INL
PURGE
A
ON
INL
PURGE
B
ON
ACTUAL
I
ACTUAL
I
PURGE
B
ON
ACTUAL
I
PURGE B OFF
SETPOINT
I
SETPOINT
I
SETPOINT
1.50 I
SETPOINT
0.10
Typical Split/Splitless Inlet Purge Displays
Automatic purge switching:
Use the steps below to switch the splitless solenoid valve on or off
automatically once during a run. The valve remains in its final state
after termination of the run.
a. To put the inlet into the splitless mode:
b. Set the on time value.
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
c. Set the off time value.
The purge A (or B) off time value should be somewhat less than the
total length of the time for the run. Inlet purge flow is switched off
automatically just prior to the end of the run to ensure that the
inlet valve is in the correct state for the start of the next run.
d. To display the time during the run when the purging will be halted:
e. To display elapsed time during the run when purging will be
restored:
Once the inlet purging event is displayed, you can enter a new
elapsed time (to 0.01 minute or similar) at any time. Elapsed time
to halt inlet purging must be prior to injection (typically 0.00). Both
on and off times are referenced to the start of the oven program.
Note: Any entered value from 0.00 through 650.00 minutes is
valid. However, the system ignores an entered time greater than
that of the run time itself and does not switch the purge valve. The
system also ignores the switch command if the programmed on and
off times are the same.
For information about EPC (constant pressure, optimizing splitless
injection), see Chapter 10, Using Electronic Pressure Control.
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Purge A (or B) ON
Total Flow Control
Septum Purge
Vent
Capillary Inlet
I
L
ml/min
●
●
●
●
●
●“
●
ACTUAL
●
●
●
SETPOINT ● ● .
Electronic Pressure Controlled
Purge A (or B) OFF
Septum Purge
Vent
Splitless Flow Diagram for Electronic Pressure Control
Setting Inlet System Flow Rates
Setting the split/splitless capillary inlet flow
Purge A (or B) ON
Total FlowControl
Septum Purge
Control
Capillary Inlet
3 ml/min
ml/min
w
Purge A (or B) OFF
Septum Purge
Purge
3 ml/min
ml/min
Control
To Detector
Splitless Flow Diagram for Manual Flow Control
91
Setting Inlet System Flow Rates
Displaying the gas flow rate
Displaying the gas flow rate
Note: If you have EPC, you will not have this feature.
If electronic flow sensing (EFS) is installed in the carrier gas system to the
inlet, you can display total supply flow rate through the system. To display
the total supply flow rate:
(EFS cannot be used with EPC inlets.) Typical gas flow rate displays are
shown below.
ACTUAL
I
FLOW A
25.4
ACTUAL
I
SETPOINT
N2
I
SETPOINT
NO F L O W S E N S O R
I
Typical Electronic Flow Rate Sensor Displays
Designating gas type
To scale the displayed flow rate value properly you must designate one of
the four commonly used gases. Select the appropriate gas type from the
table below.
Defining Type of Gas to Be Monitored
Number
1
2
3
4
92
Gas Type
He (Helium)
N 2 (Nitrogen)
H 2 (Hydrogen)
Ar/CH 4 (Methane in Argon)
Preferred Use
TCD
General
Capillary
ECD
Setting Inlet System Flow Rates
Using the internal stopwatch
Use the steps below to select one of these gases for a particular flow
channel.
The current flow rate is displayed and scaled appropriately for the chosen
gas type.
To use a gas other than the four standard gases listed above, select the
standard gas (He, N2, H2, or Ar-Me/CH4) closest in thermal conductivity to
the gas being used.
WARNING
Do not pass any corrosive gas through the EFS.
The maximum usable range for H 2 is 100 ml/min. If flow rates above 100
ml/min are used, a gas other than He, N2, or AR/CH4 is being used, or
maximum accuracy in displayed flow rate is required, you may need to
calibrate the EFS. See the HP 5890 Series II Reference Manual.
Using the internal stopwatch
The stopwatch timer is useful for setting gas flow rates and measuring
elapsed time between events of interest. In stopwatch mode, both time (to
-1
0.1 second) and reciprocal time (to 0.01 min ) are displayed
simultaneously. Use the following steps to access the stopwatch.
Stopwatch Mode
ACTUAL
I
t=o:oo.
o
SETPOINT
1 /t = 0.00
Time Display
93
5
Operating Detector
Systems
Operating Detector Systems
This chapter provides general and specific operating information for the
five HP 5890 Series II and HP 5890 Series II Plus GC detector systems:
●
Flame ionization detector (FID)
●
Thermal conductivity detector (TCD)
●
Nitrogen-phosphorus detector (NPD)
●
Electron capture detector (ECD)
●
Flame photometric detector (FPD)
Note: The Series 530 µ column supplied with the HP 5890 must be
conditioned before use. This is done by establishing a flow of carrier gas at
30 to 60 ml/min through the column while the column is heated at 250°C
for at least 4 hours. Refer to the HP 5890 Series II Reference Manual,
Preventive Maintenance.
96
Operating Detector Systems
Displaying detector status
Displaying detector status
toggles the polarity between positive and negative.
The following occurs when each detector is turned off:
FID:
The output signal and collector voltage are switched off. The flame, if
already lit, remains so until gas supplies are turned off.
NPD: The output signal, its collector voltage, and the current through its
active element are switched off.
ECD: The output signal is switched off.
TCD: The output signal, flow modulator valve, and filament current are
switched off.
FPD:
The output signal and high voltage are switched off. The flame remains
lit until gas supplies are turned off.
Typical Detector Status Displays
97
Operating Detector Systems
Turning a detector on or off
Turning a detector on or off
Caution
The TCD filament can be permanently damaged if gas flow through the
detector is off or interrupted while the detector is on. Make sure the
detector is off whenever changes/adjustments are made affecting gas
flows through the detector.
to turn it off. The change is immediately displayed.
Note that turning a detector off or on does not affect its zone temperature.
Detector temperature is controlled separately through the temperature
Temperatures.
98
Operating Detector Systems
Monitoring detector output
Monitoring detector output
Knowing the detector output is particularly useful when you initialize the
detector for operation, for example, when you light the flame for an FID,
set the power to an NPD active element, or check noise (baseline
frequency) for an ECD.
1. To display the detector output at any time, assign an output channel
(signal 1 and/or
signal 2 if installed) to a particular detector (identified by its location,
A or B).
to the particular output channel.
The figure below shows typical displays:
ACTUAL
SETPOINT
Typical Displays for Monitoring the Detector Output Signal
When detector A or B is not installed, signal 1 or 2 will be undefined. If
you try to set a detector that is not installed, the display shows that it is
not installed.
The display shows the signal in real time, reacting immediately to
anything affecting detector response. This provides a convenient method
for monitoring detector output.
Operating Detector Systems
Operating detectors using electronic pressure control
Operating detectors using electronic pressure control
This section describes general operations for detectors with EPC. The next
section describes how to set flows for systems controlled manually or
electronically.
Electronic pressure control allows you to control all auxiliary gases that
are configured using EPC from the keyboard of the HP 5890 GC.
Electronic control is available on channels C through F for auxiliary gases.
The figure below shows the HP 5890 GC keyboard, including the EPC keys
that allow you to access channels C through F:
Operating Detector Systems
Operating detectors using electronic pressure control
This section contains basic operating instructions for channels C through
F, including:
• Accessing the auxiliary channels
• Zeroing the pressure channel for calibration
● Setting
a constant pressure program
●
Setting pressure ramps
●
Changing pressure ramps
●
Verifying pressure ramps
Accessing auxiliary channels C through F
The four EPC auxiliary channels are accessed through the existing GC
keyboard by using the following keys:
To Access:
Press:
After accessing each channel, the GC display shows the channel you have
selected and the actual and setpoint values. For example, after accessing
auxiliary EPC channel C, the GC display might look like this:
EPP C
ACTUAL
SETPOINT
10.0
10.0
!
Zeroing the pressure channel
When you zero the pressure, you are compensating for background
pressure. The system is zeroed when it is shipped, but you should check it
periodically, especially when the ambient laboratory temperature changes
dramatically
101
Operating Detector Systems
Operating detectors using electronic pressure control
Note: You should zero the EPC channels 30 to 60 minutes after the system
has heated up, because changes in temperature may cause fluctuations
while the instrument heats to its final temperature.
To zero the channel accurately all flow must be removed from the system
before you enter the offset value. For each channel, you will first set the
channel to zero, and then enter the value labeled actual as the offset. The
following example zeroes channel C.
1.
Turn off all inlet and detector gases.
2.
Repressurize the inlet and detector gases to 0.0 psi.
3.
Set the auxiliary EPC channel C pressure to zero:
ACTUAL
EPP C
5.0
SETPOlNT
0.0
I
The GC display looks like this.
4.
where value is the zero offset value shown on the GC display labeled
actual.
ACTUAL
EPP C
5.O
SETPOINT
5.0
I
The GC display looks like this.
Follow the same procedure to zero the remaining auxiliary EPC
channels. Remember that the system must be completely
depressurized before entering the value labeled actual.
5. To zero channel D:
Set auxiliary channel D pressure to 0.0.
ACTUAL
I
102
EPP D
5.0
SETPOINT
5.0
I
The GC display looks like this.
Operating Detector Systems
Operating detectors using electronic pressure control
6. To zero channel E:
Set auxiliary channel E pressure to 0.0.
ACTUAL
[
5.0
EPP E
SETPOINT
5.0
|
The GC display looks like this.
I
The GC display looks like this.
7. To zero channel F:
F pressure to 0.0.
ACTUAL
I
EFP F
5.0
SETPOINT
5.0
Setting constant pressure
To set constant pressure for each of the four auxiliary channels, (where
value is the desired constant pressure value):
Note: To enter a constant pressure for a run, the initial time in the
program must be as long as (or longer than) the run time.
After setting the constant pressure for each channel, the GC display shows
the channel you have selected and the actual and setpoint pressure values.
For example, if you set EPC channel C to 60, the GC display looks like this:
ACTUAL
I
EPP C
60.0
SETPOINT
60.0
I
103
Operating Detector Systems
Operating detectors using electronic pressure control
Setting pressure ramps
To set pressure ramps for each of the four auxiliary channels (where value
is the setpoint value for the specific part of the ramp):
To set the program for EPC channel C:
To set the program for EPC channel D:
Changing pressure ramps
To change pressure ramps for each of the four auxiliary EPC channels,
follow the procedure for setting pressure ramps and enter new values for
any of the variables.
Operating Detector Systems
Operating detectors using electronic pressure control
Example of setting pressure ramps
This example shows how to enter a pressure ramp to program the gases for
a detector that is installed in the A position and controlled by auxiliary
channel D.
1. To access auxiliary channel D:
ACTUAL
1
EPP D
10.0
SETPOINT
10.0
The GC display looks like this.
2. Enter a pressure program for auxiliary channel D:
The system will now ramp the pressure as shown below:
100 psi
10 min
40 psi
5 min
Operating Detector Systems
Setting capillary makeup gas flow rate
Verifying pressure ramps
To verify pressure for each of the four auxiliary channels, access the
pressure channel to display the actual and setpoint pressure values. For
example:
I
EPP C
ACTUAL
SETPOINT
60.0
60.0
1
The GC display looks like this.
Setting capillary makeup gas flow rate
Capillary makeup gas is the gas that you add to the detector to compensate
for the low carrier gas flow rates used for capillary columns. Low carrier
gas flow must be compensated for because detectors are designed to
operate best with a carrier flow rate of at least 20 ml/min, which is typical
of packed-column GC applications. Carrier flow rates less than 10 ml/min
(typically for capillary GC applications) require capillary makeup gas to
ensure a total flow rate (carrier plus makeup) of at least 20 ml/min.
For the ECD, capillary makeup gas should be used even with HP Series
530 µ capillary columns because the detector requires high total flow rate
(at least 25 ml/min).
Exceptions to makeup gas flow
The TCD requires a total flow rate of only 5 ml/min (with about 15 ml/min
TCD reference flow). For the FID, TCD, NPD, and FPD, HP Series 530p
capillary columns may be used without capillary makeup gas as long as the
carrier flow rate is between 10 and 20 ml/min. Some loss of detector
sensitivity may occur at lower flow rates.
For the FID, NPD, and FPD, makeup gas is added directly to hydrogen
within the detector flow manifold. For an ECD or TCD, it is added into the
column gas stream via a capillary makeup gas adapter fitted into the
detector column inlet.
106
Operating Detector Systems
Setting capillary makeup gas flow rate
To set the makeup flow rate supply pressure for capillary makeup gas to
about 276 kPa (40 psi):
1. Make sure the column and makeup gas fittings (if used) are properly
installed.
2.
Turn off all gas flows through the detector except the carrier flow.
3. Adjust the column flow to the desired value for the detector and
column. Measure the flow at the detector exit with a bubble flow meter.
4.
Use the following instructions to enter the makeup gas values for
either manual or EPC systems:
Manual pressure control
a.
Set supply pressure for capillary makeup gas to about 276 kPa (40
psi).
b.
Open the auxiliary gas on/off valve. Use a small screwdriver to turn
the variable restrictor at the center of the on/off valve as necessary
to obtain the desired total flow rate (column plus makeup).
Variable Restrictor
Variable Restrictor Adjustment
Operating Detector Systems
Setting capillary makeup gas flow rate
Electronic pressure control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi.
b. Open the Aux gas (makeup gas) on/off valve completely. You will
use the auxiliary EPC pressure to control the auxiliary gas flow
rate. Be sure to open the needle valve fully by turning it clockwise
with a screwdriver.
c.
Select the pressure units you would like to use.
number of the corresponding unit you want to use:
d. The example below sets Inlet B (Injector B) pressure to 10 psi. Use
the example to set the pressure you have selected.
e.
Press:
ACTUAL
I
EPP B
10.0
SETPOINT
10.0
1
The GC display looks like this
Note: To keep the flow constant through an oven ramp program,
see Chapter 10, Using Electronic Pressure Control.
f.
5.
108
Adjust the makeup gas pressure to the detector as necessary to
obtain 30 ml/min total flow rate (column plus makeup).
Refer to the appropriate detector section to initialize the detector for
operation.
Operating Detector Systems
If the power fails . . .
If the power fails . . .
If the power fails frequently, turn off the detector whenever it is not in use.
Note: When a detector is turned on after being off, it must be given time
to stabilize before it can be used at high sensitivity. The baseline will drift
until the detector reaches equilibrium.
When power is restored after a power failure, the detector recovers to the
same state as when the power failed. The active element is restored to
“on” if it was on before the power failure.
If the gases used to light the FID or FPD are controlled with EPC, the flow
will go to zero when the power fails and return to setpoint when restored.
You will need to relight the flame after the power is turned on. For
auxiliary EPC, the GC returns to the setpoints it had before the power
failed.
Shutting down each day
On a daily basis, use the steps in the following procedure to shut down the
detector:
1.
In most cases, leave the detector on and at operating temperature to
avoid a long equilibration time at startup.
2.
Leave the carrier flow onto protect the column(s). For extended
shutdown periods, cool the oven to room temperature, and then turn
the carrier flow off.
3. With EPC applications, you can reduce the gas flows to conserve gas
and still have the detector lit and ready.
Note: For more information about the Gas Saver application, see
Chapter 10, Using the Gas Saver Application.
4. With the ECD, you may want to reduce the sensitivity by lowering the
temperature to prolong its lifetime. For extended shutdown periods,
cap off the column interface and leave a small amount of makeup gas
flowing through the system.
109
Operating Detector Systems
Operating the flame ionization detector (FID)
Operating the flame ionization detector (FID)
The flame ionization detector (FID) responds to compounds that produce
ions when burned in an H2-air flame. These include all organic
compounds, although a few (such as formic acid and formaldehyde) exhibit
poor sensitivity. This selectivity can be advantageous-for example, when
used as solvents, H2O and CS2 do not produce large solvent peaks.
Compounds Producing Little or No Response
Permanent gases
Nitrogen oxides
Silicon halides
H2O
NH 3
co
C0 2
CS2
O2
CCl4*
*Measured at the jet tip
The system is linear for most organic compounds from the minimum
detectable limit through concentrations greater than 107 times the
minimum detectable limit. Linear range depends on each specific
compound and is directly proportional to sensitivity of the FID toward the
given compound.
For maximum sensitivity, optimize the flows using standard samples
containing components of interest in expected concentrations. Use the
standard to experiment with different carrier, air, and H2 flow rates, and
determine the flow rates giving maximum response.
110
Operating Detector Systems
Operating the flame ionization detector (FID)
(i&6)
40
Hydrogen Flow
[ml/min or kPa]
(132)
In general, where sample components of interest are in high
concentration, increased air flow may be necessary (up to 650 ml/min).
Where components of interest are in low concentration, reduced air flow
rates are acceptable (375 to 425 ml/min).
Setting up the FID for operation
To setup the FID for operation, you must do the following:
. Set the flow (for either packed or capillary columns).
. Set the detector flow rates.
. Turn on the detector.
. Ignite the flame.
111
Operating Detector Systems
Operating the flame ionization detector (FID)
Hydrogen Flow
Rate versus
Pressure
80
60
Hydrogen Flow
[ml/min]
40
20
Air Flow Rate
versus Pressure
800-
600-
Air Flow
[ml/min]
400-
200-
200
100
Pressure (kPa)
400
500
Operating Detector Systems
Operating the flame ionization detector (FID)
Setting the FID flow for packed columns
The gas flow rates given in this section ensure good, reliable detector
behavior for most applications. To optimize detector behavior for a specific
application, use a standard sample matched to the application and
experimentally try other flow rates.
WARNING
Flame ionization detectors use Hz gas as fuel. If H2 flow is on and no
column is connected to the detector inlet fitting, H2 gas can flow into the
oven and create an explosion hazard. Inlet fittings must have either a
column or a cap connected at all times that H2 is supplied to the
instrument.
Note: Depending upon the column type used and the analyses to be
performed, you may have to change the jet in the FID.
Use the steps in the following procedure to set the FID flow in a packed
column. This procedure assumes that detector support gases are
connected, the system is leak-free, the correct jet is installed, and a column
is installed.
1. Close the Aux Gas on/off valve. This controls the makeup gas.
2. Set the column flow rate to 30 ml/min. Because the procedure for
setting column flow rate depends on the column installed and the inlet
system used, refer to the appropriate inlet system information in
Chapter 4.
3. Set the oven and heated zones to the desired operating temperatures.
4. Gently close the on/off controls for H2 and air by turning them
clockwise.
5. Using the flow rate versus pressure figures (shown in this section) and
the carrier gas flow rate, set supply pressures for H2 and air to obtain
the correct flow rates (30 ml/min of H2 and 430 ml/min of air are
correct for most applications).
Operating Detector Systems
Operating the flame ionization detector (FID)
You can set H 2 and air flow rates simply by setting their respective
pressures. However, if flow rates need to be verified, continue with this
section using the bubble flow meter. Otherwise, open the H 2 and air
on/off valves by turning them fully counterclockwise, and proceed to
Igniting the Flame later in this section.
6. Use the following steps to set the H2 flow rate to 30 ml/min:
a. Attach a bubble flow meter to the FID collector.
WARNING
To minimize risk of explosion when using a bubble flow meter, never
measure air and H2 together. measure them separately.
b. Open the H2 on/off valve by turning it counterclockwise. Measure
the total flow rate (column plus H 2) through the detector.
c.
Adjust the H2 pressure to the detector to obtain a total flow rate
(column plus H2) of about 30 ml/min.
d. Close the H2 on/off valve.
7. Use the following steps to set the air flow rate to 400 ml/min:
a. Open the air on/off valve by turning it counterclockwise. Measure
the total flow rate (column plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate
(column plus air) of about 430 ml/min.
8. Remove the bubble flow meter from the FID collector.
9. Open the H2 on/off valve. Proceed to Igniting the Flame later in this
chapter.
Setting the FID flow for capillary columns
WARNING
114
Flame ionization detectors use H2 gas as fuel. If H2 flow is on and no
column is connected to the detector inlet fitting, H2 gas can flow into the
oven and create an explosion hazard. Inlet fittings must have either a
column or a cap connected at all times that H 2 is supplied to the
instrument.
Operating Detector Systems
Operating the flame ionization detector (FID)
Note: Depending upon the column type used and the analyses to be
performed, you may have to change the jet in the FID.
The following table and graph show the optimal flow rates at which to
control your FID.
Typical Pressure versus Flow for FID Flow Restrictors
Values computed using ambient temperature of21‘C and pressure of 14.56 psi
Flow Restrictor
Pressure
kPa
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
psig
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
FID Makeup
HP pn 19243-60540
Green and Red Dots
Flow (ml/min)
Nitrogen
Helium
6.4
15.0
26.0
39.0
53.0
69.0
86.0
104.0
123.0
143.0
7.2
17.0
29.0
44.0
61.0
80.0
100.0
122.0
150.0
178.0
FID Hydrogen
HP pn 19231-60770
Red Dot
Flow (ml/min)
Hydrogen
18.0
44.0
77.0
116.0
162.0
211.0
264.0
322.0
383.0
445.0
FID Air
HP pn 19231-60610
Brown Dot
Flow (ml/min)
Air
65.0
157.0
273.0
410.0
561.0
726.0
900.0
1084.0
= Recommended calibration points for using EPC with the HP 3365 ChemStation
115
Operating Detector Systems
Operating the flame ionization detector (FID)
FID Restrictors
500
400
300
200
100
0
20
0
40
60
80
100
120
Pressure (psig)
Use the steps in the following procedure to set the column flow in a
capillary column. This procedure assumes that the detector support gases
are connected, the system is leak-free, the correct jet is installed, and a
column is installed.
1.
Set the column flow to the desired rate. Because the procedure for
setting column flow rate depends on the column installed and the inlet
system used, refer to the appropriate inlet system information in
Chapter 4.
2.
Set the oven and heated zones to the desired operating temperatures.
3. Adjust the carrier and makeup gas flow rate (column plus makeup)
through the detector to at least 30 ml/min.
116
Operating Detector Systems
Operating the flame ionization detector (FID)
4. Use the following steps to set manually or verify the H 2 flow rate to
approximately 30 ml/min:
WARNING
To minimize risk of explosion when using a bubble flow meter, never
measure air and H2 together. Measure them separately.
a. Attach the bubble flow meter to the FID collector.
b. Open the H2 on/off valve by turning it counterclockwise. Measure
the total flow rate (column plus makeup plus H2) through the
detector.
c. Adjust the H2 pressure to the detector to obtain a total flow rate
(column plus makeup plus H2) of about 60 ml/min.
d. Close the H2 on/off valve.
5. Use the following steps to set the air flow rate to 400 ml/min:
a. Open the air on/off valve by turning it counterclockwise. Measure
total flow rate (column plus makeup plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate
(column plus makeup plus air) of about 400 ml/min.
6. Remove the bubble flow meter from the FID collector.
7. Open the H2 on/off valve and ignite the flame.
8. Use the following instructions to enter the makeup gas values for
either manual or electronic systems.
Manual pressure control:
a. Set the supply pressure for the capillary makeup gas to about 276
kPa (40 psi).
b. Open the Aux gas (makeup gas) on/off valve by turning it
counterclockwise.
c. Use a small screwdriver to turn the variable restrictor at the center
of the on/off valve as necessary to obtain 30 ml/min total flow rate
(column plus makeup).
117
Operating Detector Systems
Operating the flame ionization detector (FID)
Electronic pressure control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi
using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable
restrictor fully counterclockwise. Then adjust the pressure to set
the desired flow rate.
c.
Select the pressure units you would like to use.
number of the corresponding unit you want to use:
d. With auxiliary EPC, makeup gas can be controlled through
auxiliary pressure channels C, D, E, or F from the keyboard. The
example below sets the auxiliary channel C pressure to 10 psi.
Press:
I
EPP C
ACTUAL
SETPOINT
10.0
10.0
1
The GC display looks like this.
Note: To keep the pressure constant through an oven ramp
program, see Chapter 10, Using Electronic Pressure Control.
e. Adjust the makeup gas pressure to the detector as necessary to
obtain 30 ml/min total flow rate (column plus makeup).
9. Gently close the on/off controls for H2 and air by turning them
clockwise.
10. Use the flow rate versus pressure graphs shown earlier in this chapter
and the carrier gas flow rate to set the supply pressures for H2 and air.
Set the supply pressures to obtain the correct flow rates. (30 ml/min of
H2 and 400 ml/min of air are correct for most applications.)
Generally you can set H2 and air flow rates simply by setting their
respective pressures. For an explanation of the relationship of flow to
118
Operating Detector Systems
Operating the flame ionization detector (FID)
pressure in an EPC system, see Chapter 10, Using Electronic Pressure
Control.
On/Off Valve, Air
Igniter Button (press to ignite)
On/Off Valve, H2
On/Off Valve, Capillary Makeup Gas
Flow Panel for Controlling FID Operation
Setting the makeup gas flow rate
Detectors are designed to operate best with a carrier flow rate of at least
20 ml/min, which is typical of packed-column GC applications. Carrier flow
rates of less than 10 ml/min (typically capillary GC applications) require
capillary makeup gas to ensure a total flow rate (carrier plus makeup) of at
least 20 ml/min.
FID sensitivity depends on the ratio of H2 to carrier flow (or carrier plus
makeup gas for capillary columns). Use the procedure described in the
following section to obtain maximum sensitivity.
You can set makeup flow rate manually or electronically. In both cases,
good laboratory practice suggests that you calibrate the system with a
bubble flow meter.
To set the makeup flow rate, set the supply pressure for capillary makeup
gas to about 276 0kPa (40 psi):
1. Make sure the column and makeup gas fittings (if used) are properly
installed.
2. Turn off all gas flows through the detector except the carrier flow.
Operating Detector Systems
Operating the flame ionization detector (FID)
3. Adjust the column flow to the desired value for the detector and
column. Measure the flow at the detector exit with a bubble flow meter.
4. Use the following instructions to enter the makeup gas values for
either manual or electronic systems.
Manual pressure control:
a. Set the supply pressure for the makeup gas to about 276 kPa
(40 psi).
b. Open the Aux gas (makeup gas) on/off valve by turning it
counterclockwise.
c.
Use a small screwdriver to turn the variable restrictor at the center
of the on/off valve as necessary to obtain the desired total flow rate
(column plus makeup).
Electronic pressure control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi
using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable
restrictor fully counterclockwise. Then adjust the pressure through
the keyboard to set the desired flow rate.
c. Select the pressure units you would like to use.
number of the corresponding unit you want to use:
d. The example below sets the auxiliary channel C pressure to 10 psi.
ACTUAL
I
120
EPP C
10.0
SETPOINT
10.0
I
The GC display looks like this
Operating Detector Systems
Operating the flame ionization detector (FID)
Note: To keep the flow constant through an oven ramp program,
see Chapter 10, Using Electronic Pressure Control.
e. Adjust the makeup gas pressure to the detector as necessary to
obtain 30 ml/min total flow rate (column plus makeup).
Turning the FID on and off
After the FID flows have been set, you can turn on the detector
electronics.
Igniting the FID flame
This procedure assumes that detector support gases are connected, the
system is leak-free, the correct jet is installed, a column is installed, and
the carrier gas and detector support gases have been set and verified at the
detector exhaust vent.
1. Open the air, H2, and makeup gas on/off valves.
Note: When using He as the capillary makeup gas, it maybe
necessary to turn off the makeup gas flow temporarily until the flame
is lit.
2. Before pressing the igniter button, enter the following:
3. Press the igniter button.
Note: You can light the FID flame regardless of whether the detector is
electronically on or off.
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
The displayed FID signal level will be in the range from 0 to 0.3 pA. When
the flame lights, the displayed signal increases to some greater steady
value (for example, 10 pA), indicating that the detector is active. The
precise value depends upon the column and operating conditions. Turn
makeup gas on if necessary.
You may also test for ignition by holding a cold, shiny surface (such as a
chrome-plated wrench) over the collector exit. Steady condensation
indicates that the flame is lit.
Operating the thermal conductivity detector (TCD)
This section assumes that all detector support gases are connected,
leak-free, and that a column is installed.
Caution
The TCD filament can be permanently damaged if gas flow through the
detector is interrupted while the filament is operating. Make sure the
detector is off whenever changes and adjustments are made affecting gas
flows through the detector.
Also, exposure to 0 2 can permanently damage the filament. Make sure
the entire flow system associated with the TCD is leak-free and that
carrier/reference gas sources are uncontaminated before turning on the
detector. Do not use Teflon tubing, either as column material or as gas
supply lines, because it is permeable to 02.
When measuring TCD flow rates, attach a bubble flow meter directly to
the detector exhaust vent using a small piece of rubber tubing as an
adapter.
Note: When measuring TCD flow rates, a bubble flow meter is attached
directly to the detector exhaust vent using a small piece of rubber tubing
as an adapter. For convenience, the HP 5890 provides a stopwatch feature
(see Chapter 4, Using the Internal Stopwatch).
122
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
On/Off Valve, Capillary Makeup Gas
On/Off Valve, Reference Gas
Setting up the TCD for operation
To setup the TCD for operation, you must do the following:
•Set the flow (for either packed or capillary columns).
●
Set the carrier gas type.
• Set the sensitivity.
• Turn on the TCD.
This section will also show you how to:
• Invert TCD polarity.
●
Use single-column compensation (SCC).
Setting the TCD flow for packed columns
The gas flow rates given in this section ensure good, reliable detector
behavior for most applications. To optimize detector behavior for a specific
application, use a standard sample matched to the application and
experiment with other flow rates.
Use the steps in the following procedure to set the TCD flow in a packed
column. This procedure assumes that detector support gases are
connected, the system is leak-free, and a column is installed.
123
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
1.
Set the detector zone temperature to the desired value (30 to 500C
greater than the maximum oven temperature to prevent sample
condensation).
Press:
2.
Set the column flow rate to 30 ml/min. Because the procedure for
setting column flow rate depends on the column installed and the inlet
system used, refer to the appropriate inlet system information in
Chapter 4.
Note: When measuring column flow rate, make sure the reference gas
flow through the detector is turned off (clockwise).
3.
Use the following steps to set the reference gas flow rate.
Note: A good guideline is to set the reference flow rate at 1.5 times
the column flow rate.
a.
Open the on/off valve for the TCD reference gas flow by turning it
counterclockwise.
b. Use a small screwdriver to turn the variable restrictor at the center
of the TCD reference gas on/off valve as necessary to obtain the
desired flow rate (45 ml/minis correct when total flow is 30
ml/min).
4.
If not already done, set the carrier gas type and detector sensitivity as
discussed later in this chapter.
Setting the TCD flow for capillary columns
Use the steps in the following procedure to set the TCD flow in a capillary
column. The gas flow rates given in this section ensure good, reliable
detector behavior for most applications. To optimize detector behavior for
a specific application, use a standard sample matched to the application
and experiment with other flow rates.
1. Set the detector temperature to the desired value (30 to 50 ‘C greater
than the maximum oven temperature to prevent sample condensation).
124
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
2. Set the column flow to 1 to 2 ml/min. Because the procedure for setting
column flow rate depends on the column installed and the inlet system
used, refer to the appropriate inlet system information in Chapter 4.
Note: When measuring column flow rate, make sure the reference gas
flow through the detector is turned off (clockwise).
3. Set the makeup gas so that the total flow rate (column plus makeup)
through the detector is 5 ml/min. Turn off the reference gas while
making this measurement.
When you use makeup gas, you should push the column all the way up
into the detector and then pull it out approximately 1 mm. However,
when you use a relatively high flow rate (and no makeup gas), the
column should be only 1 to 2 mm above the ferrule. If you want to
position the column all the way up for maximum inertness, then
continue to use makeup gas and set it to 1 to 2 ml/min.
Because a portion of the column passes through the TCD heated block
and into the cell itself do not set the zone temperature for the TCD
greater than the maximum temperature allowed for the column. A
higher zone temperature may cause column bleed.
4. Use the following instructions to enter the makeup gas values for
either manual or electronic systems. You can also control the TCD
reference gas using the same steps used
to control the makeup gas.
Manual pressure control:
a.
Set the supply pressure for capillary makeup gas to about 276 kPa
(40 psi).
b. Open the Aux gas (makeup gas) on/off valve for TCD makeup gas
flow by turning it counterclockwise.
c.
Use a small screwdriver to turn the variable restrictor at the center
of the TCD makeup gas as necessary to obtain 5 ml/min.
After the makeup gas is adjusted, the reference gas should be at
least three times the total flow rate from the column plus makeup.
Therefore, if the column plus the makeup flow is 5 ml/min, the
reference flow equals 15 ml/min.
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
d. Open the on/off valve for the TCD reference gas flow by turning it
counterclockwise.
e. Use a small screwdriver to turn the variable restrictor at the center
of the TCD reference gas on/off valve as necessary to obtain 15
ml/min.
Electronic pressure control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi
using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Turn the variable
restrictor fully counterclockwise. Then set the pressure through the
keyboard to get the desired flow rate.
Select the pressure units you would like to use.
c.
number of the corresponding unit you want to use:
d. The example below sets the auxiliary channel C pressure to 10 psi.
Press:
I
EFP C
ACTUAL
SETPOINT
10.0
10.0
I
The GC display looks like this
e. Adjust the makeup gas pressure to the detector as necessary to
obtain 30 ml/min total flow rate (column plus makeup).
5. Set the reference gas flow rate:
a.
Open the on/off valve for the TCD reference gas flow by turning it
counterclockwise.
b. Use a small screwdriver to turn the variable restrictor at the center
of the TCD reference gas on/off valve as necessary to obtain the
required flow.
126
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
6. If it is not already done, set the carrier gas and detector sensitivity as
discussed in the following sections.
Setting the TCD carrier gas type
To optimize the detector sensitivity with respect to the carrier gas used, a
switch is provided on the TCD signal board that is accessed at the top of
the instrument under the top right cover.
TCD
1. Locate the switch and place it in the position appropriate for the
carrier gas used (either N2, Ar, or He, H2).
2. To ensure the full dynamic range for the TCD, the reference gas (and
capillary makeup gas, if used) must be the same as the carrier gas.
Using different gases results in baseline offset.
Caution
The TCD filament can be permanently damaged if gas flow through the
detector is interrupted while the detector is on. Make sure that the
detector is off whenever changes and adjustments are made affecting gas
flows through the detector.
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
Setting the TCD sensitivity
Two sensitivity (signal amplification) settings are available through the
keyboard. The high- sensitivity setting increases sensitivity (area counts
observed) by a factor of 32 and is usable in applications where component
concentrations are less than 10 percent. Components that are more
concentrated may exceed the output range for the TCD, causing
flat-topped peaks. If this occurs, use the low-sensitivity setting instead.
You can change the sensitivity setting at any time without turning the
detector off. Changing the setting has no effect upon filament lifetime. To
set the TCD sensitivity from low to high:
For information on how to change TCD sensitivity during a run, see
Chapter 7, Making a Run.
Turning the TCD on and off
Caution
The TCD filament can be permanently damaged if gas flow through the
detector is interrupted while the detector is on. Make sure the detector
is off whenever changes/adjustments are made affecting gas flows
through the detector.
After TCD flows have been set, the detector maybe turned on.
Allow about l/2-hour for thermal stabilization (after the oven and zones
achieve desired setpoint values) before using the TCD.
Inverting the TCD polarity
For information on inverting the TCD signal polarity refer to Chapter 6,
Controlling Signal Output.
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
Using single-column compensation (SCC)
Because the TCD operates with only a single column, which is the
analytical column, single-column compensation (SCC) is strongly
recommended to achieve optimum baseline stability, particularly in
temperature-programmed operation.
Alternatively, if two TCDs are installed, conventional dual-column
compensation may be performed by defining the output signal as A-B
or B-A so as to output a different signal from the two detectors. This
assumes that the two detectors are operated using identical columns,
temperatures, and flow rate conditions.
The HP 5890 allows you to perform a chromatographic blank run (run
made with no sample injected) and stores the data as a baseline profile.
The baseline profile must be consistent from run to run so it can be
subtracted from the sample run data to remove baseline drift (usually
caused by column bleed).
Note: Single-column compensation data is valid only for a specific detector
and column combination, operating under defined temperature and gas
flow rate conditions. Invalid results will occur if conditions by which blank
run data is collected are different from conditions used to collect sample
run data.
Two separate profiles may be stored as designated by
detectors or two profiles for the same detector (using different
chromatographic conditions).
run if you need to abort the run at the HP 5890 GC.
and
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
Displaying the column compensation status
The status of column compensation data is displayed by pressing either
The figure below shows examples:
or
ACTUAL
I
COMP 1
-
NO
DATA
SETPOINT
ACTUAL
COMP 1
- DATA OK
COMP 1
TOO STEEP
SETPOINT
A
ACTUAL
I
1
SETPOINT
A
ACTUAL
COMP 1
No baseline profile data is presently stored
for detector A in COMP 1.
A
WRONG TIME A
Valid baseline profile data is presently
stored for detector A in COMP 1.
I
Change in baseline slope exceeds
maximum value permitted. Column
compensation data may not be valid.
I
Column compensation run aborted
SETPOlNT
compensation data may not be valid.
(Equivalent displays are possible for COMP 2 and/or detector B)
Typical Column Compensation Status Displays
or
130
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
Initiating a column compensation run
After entering the oven temperature program to be used for later sample
runs, a column compensation run is initiated by first pressing either
to display current column compensation
or
status and to designate where the new baseline profile is to be stored.
. If the desired detector (A or B) is displayed, the column compensation
. If the wrong detector is displayed, press either A or B to assign the
compensation run.
runs, using the same oven temperature program and storing a baseline
profile for each of the assigned detectors simultaneously.
This option is useful for sample analyses made using different detectors
and/or columns but using identical temperature programs.
Note: A device connected via the remote start/HP 5890 ready cable that is
started from the HP 5890 by a normal analytical run is not started by a
column compensation run.
Additional details concerning functions available at the remote receptacle
are found in the HP 5890 Series II Site Prep and Installation Manual.
Messages listed in the next figure are displayed either while a column
compensation run is in progress or if there is a problem preventing the
compensation run from starting.
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
ACTUAL
COMP 1
BLANK
RUN
ACTUAL
INVALID
DURING
RUN
SETPOINT
A
I
SETPOINT
I
Comp run in progress. In this example, data
from detector A is stored as COMP 1
Displayed if an attempt to start a column
compensation run is made while a sample
run is in progress. No column
compensation run is performed.
The oven is not on. Once the oven is
switched on, the column compensation
run begins automatically when the oven is
equilibrated at its initial temperature setpoint.
An oven tempreurprogramis not defined:
setpoint value(s) must be
entered. The temperature program defined
should be that used for sample runs. No col
umn compensation run is performed.
Chosen detector (either A or B) not
switched on. No column compensation run is
performed.
Chosen detector (either A or B) not present.
No column compensation run IS performed.
No detector(s) present. No column
compensation run is performed.
Occurs if entering new oven temperature
program setpoints is attempted during a
column compensation run. Entries are
ignored. Also occurs if an attempt is made to
start a column compensation run while one is
already in progress. The one in progress
continues to normal completion.
Typical Column Compensation Message Displays
132
Operating Detector Systems
Operating the thermal conductivity detector (TCD)
A column compensation run terminates automatically at the completion of
its oven temperature program. Any existing baseline profile is erased as
data for the new baseline profile is collected and stored.
Note that the oven temperature program for a column compensation run
follows setpoint values for initial time, rate, and final time as in an
analytical run. Data is stored, however, only for rate and final time
portions of the temperature program.
to abort a column compensation run
when the baseline profile stored is probably not valid (because the oven
temperature program will not have reached the final temperature
setpoint). A message WRONG TIME is displayed to indicate that a mismatch
has occurred between the expected length of time for the run versus the
actual time.
After baseline data for a given detector is stored as either COMP 1 or
COMP 2, the column compensation data must be assigned to a specific
detector signal. During a run, the compensation data is subtracted from
run data for the same detector.
The following key sequence assigns such baseline-corrected data to a
particular output channel:
The figure below illustrates the display confirming the assignment:
SETPOINT
ACTUAL
I
SIGNAL
1 A - COMP
1
1
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Note: No internal verification is given by the HP 5890 to ensure that
compensation data collected on a given detector is assigned later to be
subtracted from the same detector via the above key sequence. If you get
strange baseline behavior from subtracting compensation data:
• Compensation data itself is suspected.
• Data acquired from a different detector has been assigned.
•Chromatographic conditions used for sample analyses are different
from those used for the original column compensation run.
After you assign a particular output channel, sample analyses are
performed in the usual manner, the only difference being that the observed
baseline should be relatively free of drift.
Operating the nitrogen-phosphorus detector (NPD)
The nitrogen-phosphorus detector (NPD) uses a jet and collector similar to
the FID. However, the collector contains a small alumina cylinder coated
with a rubidium salt (the active element), which is heated electrically,
creating a thermionicsource. In this environment, nitrogen and
phosphorus containing organic molecules are ionized. The detector collects
the ions and measures the resulting current.
As with an FID, an NPD requires hydrogen and air, but at lower flows.
Therefore, normal FID-type ionizations are minimal, as is response to
compounds not containing nitrogen or phosphorus. Thus, the detector is
both sensitive to and selective of compounds containing nitrogen and/or
phosphorus.
The electrical power for heating the active element is supplied through a
toroidal transformer located inside the NPD cover. The toroidal
transformer secondary winding is connected directly to the collector/active
element assembly. The electrical heating current passes directly through
the small platinum wire that is also used to position the active element
inside the collector.
134
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
The active element of the NPD operates in a very delicate thermal balance
that depends on several different variables. The magnitude of the response
of the NPD is a function of the temperature of the active element and of
the active zone around the active element itself. Because of this
temperature dependence, the output of the detector is very sensitive to
anything that affects the temperature of this active zone. Important
variables and their effects include the following:
●
Increasing detector temperature increases the active element
temperature and the response.
●
Increasing the electrical power to the active element increases both the
temperature of the active element and the response.
●
Increasing the hydrogen flow increases the temperature of the active
element as well as the size of the active zone around the active
element; both effects result in increased response.
●
Increasing the air flow to the detector normally cools the active
element slightly and decreases the response. (The change in
temperature from altering the air flow is much less than the change
from altering the hydrogen flow.) Increasing the air flow also decreases
the residence time of a given peak in the active zone of the active
element and decreases response.
●
Increasing the carrier gas flow cools the active zone slightly and
decreases the residence time of a component in the active zone, which
decreases the response.
A hydrogen flow rate that is too high may cause a true flame around the
active element. This would severely overheat the active element and
destroy the specific response. An air flow rate that is too low may quench
the background response of the active element, resulting in a
reequilibration time that is too long to establish a proper background
response (negative solvent peaks kill the active element).
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Setting up the NPD for operation
To setup your NPD, you must do the following:
• Set the flow (for either packed or capillary columns).
• Condition the active element (bead).
• Set the active element power.
•Turn on the NPD.
Valve, Capillary Makeup Gas
Flow Panel Controlling NPD Operation
Conditioning the NPD active element (bead)
Condition the NPD active element (bead) when you install a new element
or when the detector has been turned off for a period of time. Conditioning
removes water that may have been absorbed into the active element from
humidity in the air. If the active element is electrically heated too rapidly,
the rubidium coating on the active element can fracture and ruin the
collector.
This section assumes that the detector support gases are connected, the
system is leak-free, the correct jet is installed, and a column is installed.
1. Set and turn on the carrier and detector gases.
2. Turn the active element power control fully counterclockwise to set the
power to 000.
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Note: The locking lever immediately below the control knob is locked
in the right-most position and unlocked in the left-most position.
3. Turn off the power to the detector and the active element by pressing:
0
4. Set the oven temperature to 50 C
5. With the carrier and detector gases flowing, raise the temperature of
the detector’s isothermal zone to 2200C. Allow the collector to
condition for at least 30 minutes under these conditions.
Note: If your detector is exposed to high humidity, condition new
collectors for a longer period (overnight).
After the active element has been dried, initiate the specific NPD
response by setting the power to the active element.
I
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Setting the NPD active element (bead) power
Control
Lock
NPD Active Element (Bead) Power Control
The following procedure sets the correct operating temperature for the
active element. Operating at a temperature higher than the recommended
range produces greater sensitivity at the expense of increased noise and
reduced element lifetime with no increase in minimum detectable limit.
The temperature of the active element in the NPD collector is controlled
by a 10-turn rotary control located below the keyboard. A mechanical
counter (000 through 999) registers the position of the control.
138
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Before setting the active element power, install a column and set the NPD
flows as explained later in this section.
1. Set the heated zones to the desired operating temperatures. Leave the
oven at 500C
Note: The temperature of the heated zone should be at least 200°C.
2. Turn off the power to the detector and the active element by pressing:
WARNING
Do not leave the detector on while setting the active element power; it
may overheat and become permanently damaged.
3. Set the active element power control to 000 by turning it fully
counterclockwise.
Note: The locking lever immediately below the control knob is locked
in the right-most postion and unlocked in the left-most position.
4. Before setting the active element power, enter the following:
The displayed value on the Oven/Det status window is in pA and
should be close to zero. Allow approximately 1 minute for the baseline
to stabilize.
5. Increase the element power slowly by turning the active element power
control clockwise in steps of 100 (waiting 1 minute in between steps)
until the displayed signal value approaches the target value. Expect
little or no change at first, then a rapid increase as the element
becomes active.
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Generally the detector is adequately sensitive when enough power is
supplied to the active element to display a signal output value in the
range of 20–30 pA.
Note: Operational power settings vary depending on the hydrogen and
air flow rate, the detector temperature, contamination, and the desired
sensitivity For the conditions in this procedure, typical values range
from 400–900. The power control can probably be increased
immediately to 300–400 while giving a negligible increase in offset on
the detector. As higher power settings are approached (500–600),
increase the power more slowly and carefully
If you know the element power setting, bring power slowly to the
setting and fine-tune if necessary. Wait for the baseline to stabilize
before setting a final value.
After reaching the proper range of offset, allow the detector to stabilize
before expecting precise measurements. The offset may drift until the
active element becomes fully acclimated to the operating conditions.
During this period, the apparent sensitivity of the detector will change.
Setting the NPD flow for packed columns
The gas flow rates outlined in this procedure ensure good, reliable detector
behavior for the majority of analyses. If it is necessary to modify the flow
rates for a specific application, use a standard sample matched to the
application and experiment with the flow rates to optimize the detector’s
behavior.
WARNING
To minimize the risk of explosion when using a bubble flow meter, never
measure air and hydrogen together. measure them separately.
This section assumes that the detector support gases are connected, the
system is leak-free, the correct jet is installed, and a column is installed.
140
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
1. Close the Aux gas on/off valve.
2. Attach a bubble flow meter to the NPD collector using the rubber
adapter.
3. Set the column flow to approximately 20 ml/min.
4. Set the oven and the heated zones to the desired operating
temperatures.
5. Set the column flow rate to 20 ml/min. Because the procedure for
setting the column flow rate depends on the type of column installed
and inlet system used, refer to the information about the appropriate
inlet system in Chapter 4, Setting Inlet System Flow Rates.
6. Use the following steps to set the H2 flow rate to 3 to 4 ml/min:
a. Open the H2 on/off valve by turning it counterclockwise. Measure
the total flow rate (column plus makeup) through the detector.
b. Adjust the H2 pressure to the detector to obtain a total flow rate
(H2plus column) of 23 to 24 ml/min.
c. Turn the H2 off.
7. Use the following steps to set the air flow rate to 100 to 120 ml/min:
a.
Open the air on/off valve by turning it counterclockwise. Measure
the total flow
(column plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow of 120
to 140 ml/min.
c.
Turn the air flow off.
8. Remove the flow measuring adapter and bubble flow meter from the
NPD collector.
9. Open the H2 on/off valve.
Setting the NPD flow for capillary columns
The table and graph on the following page show the pressure and flow
values for EPC of the NPD.
141
Operating DetectorSystems
Operating the nitrogen-phosphorus detector (NPD)
Typical Pressure versus Flow for FID Flow Restrictors
Values computed using ambient temperature of 21°C and pressure of 14.56 psi
Flow Restrictor
Pressure
kPa
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
psig
FID Makeup
HP pn 19243-60540
Green and Red Dots
Flow (ml/min)
Nitrogen
FID Air
HP pn 19234-60600
Brown Dot
Flow (ml/min)
FID Hydrogen
HP pn 19231-60660
Red Dot
Flow (ml/min)
Helium
Air
Hydrogen
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
= Recommended calibration points for using EPC with the HP 3365 ChemStation
400
20
300
15
200
10
100
5
0
0
o
20
40
60
Pressure (psig)
NPD Restrictors
80
100
120
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
WARNING
To minimize the risk of explosion when using a bubble flow meter, never
measure air and hydrogen together. measure them separately.
This section assumes that the detector support gases are connected, the
system is leak-free, the correct jet is installed, and a column is installed.
1. Set the oven and the heated zones to the desired operating
temperatures.
2. Set the column flow rate to the desired value. Because the procedure
for setting the column flow rate depends on the type of column
installed and inlet system used, refer to the information about the
appropriate inlet system in Chapter 4.
3. Adjust the total carrier and makeup gas flow (column plus makeup) to
at least 30 ml/min.
4. Attach a bubble flow meter to the NPD collector using the rubber flow
measuring adapter.
5. Use the following steps to set the capillary makeup gas flow rate for
either manual or electronic pressure control.
Manual pressure control:
a.
Set the supply pressure for the capillary makeup gas to about
276 kPa 40 psi).
b. Open the Aux gas on/off valve by turning it counterclockwise.
Measure the total flow rate (column plus makeup) through the
detector.
c.
Use a small screwdriver to turn the variable restrictor at the center
of the on/off valve to obtain a total flow rate of 30 ml/min (column
plus makeup).
d. Use the following steps to set the H2 flow rate to 3 to 4 ml/min:
i. Open the H2 on/off valve by turning it counterclockwise.
Measure the total flow rate (column plus makeup plus H 2)
through the detector.
143
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
ii. Adjust the Hz pressure to the detector until the total flow
reaches 33 to 34 ml/min.
...
111. Turn the H2 flow off.
e. Use the following steps to set the air flow rate to 100 to 120 ml/min:
i. Open the air on/off valve by turning it counterclockwise.
Measure the total flow rate (column plus makeup plus air)
through the detector.
ii. Adjust the air pressure to the detector until it reaches
100– 120 ml/min.
Electronic pressure control:
a.
Set the supply pressure to the auxiliary EPC channel to 40 psi.
b.
Open the Aux gas (makeup gas) on/off valve. Turn the variable
restrictor valve fully counterclockwise. Then adjust the pressure to
get the desired flow rate.
c.
Select the pressure units you would like to use.
number of the corresponding unit you want to use:
d.
The example below sets the auxiliary channel C pressure to 10 psi.
Press:
Sets auxiliary channel C pressure to 10 psi.
I
EPP C
ACTUAL
SETPOINT
10.0
10.0
I
The GC display looks like this
Note: To keep the pressure constant through an oven ramp
program, see Chapter 10, Using Electronic Pressure Control.
e.
144
Adjust the makeup gas pressure to the detector as necessary to
obtain 30 ml/min total flow rate (column plus makeup).
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
6. Remove the bubble flow meter from the NPD collector.
7. Open the H2 on/off valve.
Turning the NPD on and off
WARNING
Do not leave the detector on while setting the active element power; it
may overheat and be permanently damaged.
After the oven and zones reach the desired setpoint values, wait an
additional ½hour before using the NPD.
Optimizing the performance of the NPD
To optimize the performance of the NPD, you should avoid contamination
of the detector and preserve the lifetime of the active element (bead).
Avoiding contamination
The slightest contamination can create serious NPD problems. The
following list describes common sources of contamination to avoid:
• Columns and/or glass wool treated with H 3PO 4 (phosphoric acid)
• Phosphate-containing detergents
• Cyano-substituted silicone column (such as XE-60 and OV-225)
• Nitrogen-containing liquid phases
●
Any liquid phase deactivated for analysis of basic compounds
•
●
Fingerprints
Leak-detection fluids
• Laboratory air
145
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
Contamination may affect the performance of an NPD in two ways:
• Positive contamination gives a more positive offset than what would
normally result from a clean system. In response to the positive offset,
you may operate the detector with too little power to the active
element. Because the temperature of the active element is less than
normal, the detector appears less sensitive than is desirable.
• Negative contamination quenches the reaction, resulting in decreased
sensitivity. Very high contamination may completely quench all signals
from the detector. If this happens, the apex of a peak is flattened
toward the baseline.
Preserving the lifetime of the active element
The lifetime of the active element is reduced by silicon dioxide coating, loss
of rubidium salt, and humidity. Observe the following suggestions to
preserve the lifetime of the active element:
Prevent silicon dioxide from coating the active element. Residual
silanizing reagents from derivatization, and/or bleed from silicone
columns, may coat the active element with silicon dioxide. This
decreases ionization efficiency reducing sensitivity.
If silanizing is necessary, remove excess reagent before injection.
Silicone columns should be well conditioned and loaded less than 5%.
●
Do not overheat the active element. Rubidium loss is caused by
overheating the active element, particularly if the element power is on
when gas flows are interrupted (especially in the carrier). You must
turn off the detector or reduce the element power to zero when
changing the columns and/or replacing the gas cylinders. Power to the
element while the gas flow is off can destroy an element within a few
minutes.
Use the lowest element power possible, consistent with maintaining
sufficient detector sensitivity and selectivity for the particular
analyses.
Reduce the power to the active element whenever the detector will not
be operated for extended periods of time (such as over the weekend).
146
Operating Detector Systems
Operating the nitrogen-phosphorus detector (NPD)
To determine the proper amount of power reduction, plot the normal
offset and note the displayed zero value (20–30 is in the normal
range). Then reduce the power setting slightly until the displayed zero
value (offset) just goes to zero or to a value close to zero (lower than 5
picoamps). In this way, the temperature of the active element will be
lowered such that there will be little loss of rubidium, but the active
element will still be kept hot enough to prevent contamination
(condensation) while in standby.
●
If you are using the auxiliary EPC channel to control the NPD gases,
you can program hydrogen to a lower value. This cools the bead and
thereby extends the bead life.
●
Counteract humidity. Humidity adversely affects the lifetime of an
element. Keep the detector warm (l00°C to 150°C) when it is not in
use. Store the collector (including spare collectors) in a desiccator
whenever you remove it from the NPD for an extended period of time.
●
Recoat or replace an old element. Invest in a recoating kit, which
rejuvenates the active element in an old collector. Also keep a spare
collector available as a replacement.
●
Generally sensitivity and selectivity to nitrogen decreases as the
element ages. Phosphorus response is affected less than nitrogen
response.
●
Do not remove the seals that cover the NPD during shipments until
you are ready to connect the column and operate the detector. Without
the seals, the active element may become contaminated, which will
reduce the collector’s effectiveness and possibly ruin the active
element.
Both the detector baseline and sensitivity change with the carrier flow rate
due to changes in the temperature of the active element. This causes
baseline drift in pressure-controlled inlet systems (capillary inlets) while
temperature-programming the column. The amount of change in the
detector response is proportional to the ratio of the total column flow
change (temperature sensitive) to the makeup gas flow (not temperature
sensitive); that is, total column flow change divided by makeup gas flow.
Adjust the element power after any change in the carrier flow rate.
147
Operating Detector Systems
Operating the electron capture detector (ECD)
When the detector is first turned on, its sensitivity and signal level change
slowly over several hours. Therefore, for applications requiring very stable
operation, leave the detector on overnight, lowering the oven temperature
to prevent contaminating the active element with column bleed.
Operating the electron capture detector (ECD)
This section explains how to operate an electron capture detector (ECD).
Specifically, it describes the following:
• The basic operating characteristics of an ECD
• General issues to consider when using an ECD, including temperature,
gases, flow rates, and background
• Routine detector operating procedures, including setting the column
flow, setting the carrier gas selection switch, setting carrier gas and
makeup gas flow rates, and performing daily startup and shutdown
procedures.
WARNING
The gas stream from the detector must be vented to a fume hood to
prevent possible contamination of the laboratory with radioactive
material. For cleaning procedures, see Cleaning the detector in this
chapter.
Requirements for USA owners
WARNING
Detector venting must be in conformance with the latest revision of
Title 10, Code of Federal Regulations, Part 20 (including Appendix B).
The detector is sold under general license: owners may not open the
detector cell or use solvents to clean it. Additional information is
available in the publication information for general licensees, Pub. No.
43-5953-1586 (D).
Owners of this detector must perform a radioactive leak test (wipe test)
at least every 6 months. See Testing for radioactive leaks (the wipe test)
in this chapter.
148
Operating Detector Systems
Operating the electron capture detector (ECD)
WARNING
In the extremely unlikely event that both the oven and the ECD-heated
zone should go into thermal runaway (maximum, uncontrolled heating
in excess of 400°C) at the same time, and that the ECD remains exposed
to this condition for more than 12 hours, take the following steps:
●
After turning off the main power and allowing the instrument to
cool, cap the ECD inlet and exhaust vent openings. Wear disposable
plastic gloves and observe normal safety precautions.
Ž Return the cell for exchange following the directions included with
the form general license certification (HP Pub. No. 43-5954-7621,
HP part number 19233-90750).
Even in this very unusual situation, radioactive material is unlikely to
63
escape the cell. Permanent damage to the Ni plating within the cell is
possible, however, so the cell must be returned for exchange.
Introduction
The electron capture detector (ECD) cell contains 63Ni, a radioactive
isotope emitting high-energy electrons (ß-particles). These undergo
repeated collisions with carrier gas molecules, producing about 100
secondary electrons for each initial ß-particle.
Further collisions reduce the energy of these electrons into the thermal
range. These low-energy electrons are then captured by suitable sample
molecules, thus reducing the total electron population within the cell.
Uncaptured electrons are collected periodically by applying short-term
voltage pulses to the cell electrodes. This cell current is measured and
compared to a reference current. The pulse interval is then adjusted to
maintain constant cell current.
Therefore pulse rate (frequency) rises when an electron-capturing
compound passes through the cell. The pulse rate is converted to a voltage,
which is related to the amount of electron-capturing material in the cell.
The ECD responds to compounds having an affinity for electrons—for
example, halogenated materials such as pesticides and related compounds.
149
Operating Detector Systems
Operating the electron capture detector (ECD)
The following table shows expected sensitivities to different classes of
organic compounds.
General considerations
General ECD Sensitivity to Various Classes of Compounds
Chemical Type
Relative Sensitivity
Hydrocarbons
1
Ethers, esters
Aliphatic alcohols, ketones, amines;
mono-Cl, mono-F compounds
Mono-Br, di-Cl and di-F compounds
Anhydrides and tri-Cl compounds
Mono-1, di-Br and nitro compounds
Di-l, tri-Br, poly-Cl and poly-F compounds
10
102
1 03
1 04
1 05
10 6
The figures in the table are only approximate, and sensitivity varies widely
within each group, depending on the structure of the material. For
example, DDT with 5 chlorine atoms per molecule can be measured in the
1-to 10-picogram range.
Temperature effects
Some compounds exhibit strong response to detector temperature. The
effect may be either positive or negative. Try different detector
temperatures above the oven temperature to determine the effect on
sensitivity Generally, a detector temperature between 250 and 300ºC is
satisfactory for most applications.
Gases
The ECD is designed for use with either nitrogen or argon-methane as
carrier gas. Nitrogen yields somewhat higher sensitivity with
approximately the same minimum detectable limit, but is also
accompanied by higher noise and occasional negative solvent peaks.
Argon-methane gives a greater dynamic range. Use the appropriate switch
to select carrier gas type. The ECD does not operate properly if the switch
is set incorrectly.
Operating Detector Systems
Operating the electron capture detector (ECD)
Because of its high sensitivity never use the ECD without moisture,
chemical, and 02 traps in carrier and makeup lines. The traps should be in
good condition and installed in the carrier gas supply line and the makeup
gas supply. Also, avoid using plastic tubing, which is permeable to most
gases, for all connections. Use clean copper tubing instead.
Columns and flow rates
An ECD is normally used to detect compounds that are reactive enough to
interact with metal columns. Therefore, only l/4-inch packed glass or
fused silica capillary columns are recommended with this detector.
Hydrogen carrier gas (with nitrogen makeup gas) gives the best column
performance.
Argon-methane can also be used as makeup gas. For most purposes,
50-60 ml/min of makeup gas is satisfactory, but the rate maybe increased
to 100 ml/min for very fast runs. Because the ECD is a concentrationdependent detector, increasing the flow rate reduces sensitivity but can
extend the linear range.
Note: When measuring ECD flow rates, attach a bubble flow meter
directly to the detector exhaust vent using a small piece of rubber tubing
as an adapter.
Background
If the ECD becomes contaminated from impurities in the carrier (or
makeup) gas or from column bleed, a significant fraction of detector
dynamic range may be lost. In addition, the output signal becomes noisy.
To check the background level, allow ample time for the components from
the previous analyses to be flushed from the system and then make a
blank run (one with no sample injected).
Setting up the ECD for operation
To setup the ECD for operation, you must:
•Set the carrier gas selection switch (if it is not done already).
• Set the ECD flow (for either packed or capillary columns).
Operating Detector Systems
Operating the electron capture detector (ECD)
Setting the carrier/makeup gas selection switch
The carrier gas selection switch is located on the detector board behind the
right instrument side panel. Use the following procedure to set the carrier
gas selection switch if necessary:
1. Turn off the power and unplug the instrument.
2.
Remove the top right cover by lifting first at its rear edge and then
sliding it toward the rear of the instrument.
3.
Remove the right side panel by removing four screws, two along its
bottom edge and two along its top edge.
4.
Locate the ECD signal board, which is next to the detector.
5.
Locate the N2-ArCH 4switch and place it in the appropriate position
based on the type of predominant gas at the detector (carrier or
makeup).
6.
Replace the panels.
ECD Carrier Gas Selector Switch
152
Operating Detector Systems
Operating the electron capture detector (ECD)
Setting the ECD flow for packed columns
Gas flow rates given in this section ensure good, reliable detector behavior
for most applications. To optimize detector behavior for a specific
application, use a standard sample matched to the application and
experiment with other flow rates.
Use the steps in the following procedure to set the ECD flow in the
column. This procedure assumes that the detector support gases are
connected, the system is leak-free, and a column is installed. If your
system has electronic pressure control, enter the flows at the keyboard
using the Electronic pressure control instructions.
1. Set the column flow to the desired rate. Because the procedure for
setting the column flow rate depends on the column installed and the
inlet system in use, refer to the appropriate system information in
Chapter 4.
2. Open the ECD Anode Purge On/Off valve. Supply pressure of 30 psi
will deliver approximately 3 ml/min of purge flow. ECD anode purge
flow is not considered part of total column flow.
Packed column considerations: Either N2 or Ar containing 5% CH4
may be used as carrier gas. N2 yields somewhat higher sensitivity, but it is
accompanied by higher noise; minimum detectable limit is about the same.
N2 sometimes produces a negative solvent peak. Ar/CH 4 gives greater
dynamic range.
Total flow of 60 ml/min is adequate in most applications to prevent peak
broadening and maximize linearity.
The carrier gas must be dry and 02-free. Moisture and 02 traps are
strongly recommended for highest sensitivity. Because plastic tubing is
permeable to many gases, the use of clean copper tubing is recommended
for all connections.
Operating Detector Systems
Operating the electron capture detector (ECD)
Setting the ECD flow for capillary columns
The following table and graph show the optimal pressure and flow values
for EPC or the ECD.
Typical Pressure versus Flow for ECD Flow Restrictors
Values computed using ambient temperature of 21°C and pressure of 14.56 psi
Flow Restrictor
Pressure
kPa
psig
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
ECD Makeup
HP pn 19231-60770
Red Dots
Flow (ml/min)
Nitrogen
Argon-Methane
10.0
100.0
= Recommended calibration points for using EPC with the
HP 3365 ChemStation
Note: The anode purge flow rates will be approximately l/10th of the
values shown above at the same pressure settings.
50
0
1.
Set the column flow to the desired rate. Because the procedure for
setting column flow rate depends on the column installed and the inlet
system used, refer to the appropriate system information in Chapter 4.
Supply pressure for the makeup gas and anode purge should be set to
207 kPa (30 psi).
2. Open (counterclockwise) the On/Off valve for ECD makeup gas flow.
Supply pressure of 60 psi will deliver approximately 60 ml/min of
makeup gas flow.
3. Open the ECD Anode Purge
— On/Off valve. Supply pressure of 60 psi
will deliver approximately 6 ml/min of purge flow. ECD anode purge
flow is considered part of total column flow.
155
Operating Detector Systems
Operating the electron capture detector (ECD)
Capillary column considerations: H2 or He carrier gas affords the best
column performance with reduced retention times. Ar/CH4 or N2 as
makeup gas is used in the range of 60 ml/min. Because the ECD is a
concentration-dependent detector, reduced sensitivity is obtained at higher
flow rates.
For the ECD, capillary makeup gas should be used even with HP Series
530 µ capillary columns because the detector requires a total flow rate of at
least 25 ml/min.
Moisture and 02 traps for carrier and makeup gas are essential with
capillary/ECD operation.
Your ECD makeup gas is equipped with either manual or electronic
pressure control. Set the makeup gas according to the instructions for
your instrument.
Manual pressure control:
a. Set the supply pressure for the capillary makeup gas to about
276 kPa (40 psi).
b. Open the on/off valve for the ECD makeup gas flow by turning it
counterclockwise.
c.
Use a small screwdriver to turn the variable restrictor at the center
of the on/off valve as necessary to obtain a flow of 60 ml/min.
Electronic pressure control:
a. Set the supply pressure to the auxiliary EPC channel to 40 psi.
b. Open the Aux gas (makeup gas) on/off valve. You will use the
auxiliary EPC pressure to control the auxiliary gas flow rate.
c. Select the pressure units you would like to use.
number of the corresponding unit you want to use:
156
Operating Detector Systems
Operating the electron capture detector (ECD)
d. With electronic pressure control, makeup gas is controlled through
auxiliary pressure channels C, D, E, or F from the keyboard. The
example below sets the auxiliary channel C pressure to 40 psi.
I
EPP C
ACTUAL
SETPOlNT
40.0
40.0
I
The GC display looks like this
Note: To keep the pressure constant through an oven ramp
program, see Chapter 10, Using Electronic Pressure Control.
e. Adjust the makeup gas pressure to the detector as necessary to
obtain an appropriate total flow rate (column plus makeup).
For the ECD, use capillary makeup gas even with HP Series 530 µ capillary
columns because the large cell size requires high total flow rate (at least
50–60 ml/min).
For an ECD, the makeup gas is added into the column effluent stream via
a capillary makeup gas adapter fitted into the detector column inlet.
Testing for contamination
Because of its very high sensitivity the ECD is particularly prone to
contamination problems, including contaminants entering the system via
the carrier and makeup gas source.
Perform the following procedure whenever a new carrier gas source is
installed:
1. With the instrument on and operating normally, cool the oven to
ambient temperature, turn off the detector, turn off carrier flow to the
detector, and remove the column to the ECD. If a capillary column was
installed, also remove the makeup gas adapter in the detector base.
Operating Detector Systems
Operating the electron capture detector (ECD)
2. Disconnect the carrier gas source line at its fitting on the rear of the
inlet used.
Note: If your carrier gas is helium or hydrogen (not N 2 or Ar-CH4),
then use the makeup gas, not the carrier gas.
3. Using a Vespel ferrule, and adapters as necessary, connect the carrier
source line to the detector base, including any traps in the line.
4. Set the carrier pressure to about 7 kPa (1 psi) and check for flow
through the detector.
5. Leaving the oven door open, enter any temperature for the detector up
to 250°C.
6. Turn on the detector electronics.
7. Assign the ECD to one of the monitored signals.
8. Within 15 minutes, the displayed signal values on the Oven\Det Status
window should be between 40 to 100 (400 to 1,000 Hz); there may be
downward drift.
9. If the displayed values are greater than 1,000 Hz, the trap(s) maybe at
fault. Connect the carrier gas supply line directly to the detector base
and repeat the test. If the values are still out of range, then the carrier
gas supply or the detector maybe contaminated. Try a new tank of N2
or Ar-CH4. If the system is fine, then the gas was contaminated. If not,
the cell is probably dirty and should be exchanged.
Operating Detector Systems
Operating the electron capture detector (ECD)
Testing for leaks
Note: This test assumes that the flow system components upstream from
the detector are leak-free.
Use the steps in the following procedure to test for leaks at the ECD:
1.
Set the inlet, oven, and detector to ambient temperature and allow
time for cooling. Turn off the detector and carrier flow.
2. Use a vent plug to cap the ECD exhaust vent.
3. Set the carrier gas pressure to an appropriate valve depending on the
inlet system you are using. Open the carrier gas mass flow controller
fully to ensure that flow through the system is available. Allow time for
the system to become fully pressurized.
4. Close the carrier gas flow at its source and monitor system pressure.
5. If no pressure drop is observed over a 10-minute period, assume that
the system is leak-free.
6. If leakage is observed, use an appropriate electronic leak detector to
check for leaks at the detector column fittings and at the plugged vent.
Note: The detector body itself is not a likely source of leaks. It cannot
be disassembled without special license from the Nuclear Regulatory
Commission or Agreement State Licensing Agency (USA only).
Testing for radioactive leaks (the wipe test)
ECDs must be tested for radioactive leaks at least every 6 months. Records
of tests and results must be maintained for possible inspection by the
Nuclear Regulatory Commission and/or responsible state agency. More
frequent tests may be conducted when necessary
A wipe test kit, supplied with each new ECD, contains complete
instructions for conducting the test.
159
Operating Detector Systems
Operating the flame photometric detector (FPD)
Operating the flame photometric detector (FPD)
Flow Panel for Controlling FPD Operation
Setting up the FPD for operation
To setup the FPD for operation, you must:
• Set the FPD flow (for either packed or capillary columns).
• Set the FPD sensitivity.
• Turn on the FPD.
Operating Detector Systems
Operating the flame photometric detector (FPD)
Setting the FPD flow for packed columns
The gas flow rates given in this section ensure good, reliable detector
behavior for most applications. To optimize detector behavior for a specific
application, use a standard sample matched to the application and
experiment with other flow rates.
WARNING
Flame photometric detectors use hydrogen gas as fuel. if hydrogen flow
is on and no column is connected to the detector inlet fitting, hydrogen
gas can flow into the oven and create an explosion hazard. Inlet fittings
must have either a column or a cap connected whenever hydrogen is
supplied to the instrument.
Use the steps in the following procedure to set the FPD flow in a packed
column. This procedure assumes that detector support gases are
connected, the system is leak-free, and a column is installed.
1. Close the Aux gas on/off valve.
2. Set the column flow rate to 20 ml/min. Because the procedure for
setting column flow rate depends on the column installed and the inlet
system used, refer to the appropriate inlet system information in
Chapter 4.
3. Set the oven and heated zones to the desired operating temperatures.
4. Attach a bubble flow meter to the FPD vent tube.
WARNING
To minimize risk of explosion when using a bubble flow meter, never
measure air and hydrogen together. Measure them separately.
To optimize sulfur sensitivity use a lower hydrogen flow rate
(50–60 ml/minis recommended). To optimize phosphorus sensitivity
use a higher hydrogen flow rate (about 100 ml/min is recommended).
Operating Detector Systems
Operating the flame photometric detector (FPD)
5. Use the following steps to set the H2 flow rate to 75 ml/min:
a. Open the H2 on/off valve by turning it counterclockwise. Measure
the total flow rate (column plus H2) through the detector.
b. Adjust the H2 pressure to the detector to obtain a total flow rate
(column plus H2) of about 95 ml/min.
c. Close the H2 on/off valve.
6. Use the following steps to set the air flow rate to 100 ml/min.
a. Open the air on/off valve by turning it counterclockwise and
measure the total flow rate (column plus air) through the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate
(column plus air) to
120 ml/min.
7. Remove the measuring adapter from the FPD collector.
8. Open the H2 on/off valve. To ignite the flame, see Igniting the FPD
flame later in this chapter.
Setting the FPD flow for capillary columns
This table and graph show the optimal flow rates at which to control your
FPD with EPC.
162
Operating Detector Systems
Operating the flame photometric detector (FPD)
Typical Pressure versus Flow for FPD Flow Restrictors
Values computed using ambient temperature of 21°C and pressure of 14.56 psi
FPD Makeup
HP pn 19243-60540
Green and Red Dots
Flow (ml/min)
Flow Restrictor
Pressure
FPD Hydrogen
HP pn 19234-60570
Red Dot
Flow (mI/min)
FPD Air
HP pn 19234-60570
Brown Dot
Flow (ml/min)
= Recommended calibration points for using EPC with the HP 3365 ChemStation
300
250
200
150
0
0
20
40
60
Pressure (psig)
FPD Restrictors
80
100
120
Operating Detector Systems
Operating the flame photometric detector (FPD)
The gas flow rates given in this section ensure good, reliable detector
behavior for most applications. To optimize detector behavior for a specific
application, use a standard sample matched to the application and
experiment with other flow rates.
WARNING
Flame photometric detectors use hydrogen gas as fuel. If hydrogen flow
is on and no column is connected to the detector inlet fitting, hydrogen
gas can flow into the oven and create an explosion hazard. Inlet fittings
must have either a column or a cap connected whenever hydrogen is
supplied to the instrument.
Use the steps in the following procedure to set the FPD flow in a capillary
column. This procedure assumes that the detector support gases are
connected, the system is leak-free, and a column is installed.
1.
Set the oven and the heated zones to the desired operating
temperatures.
2.
Set the column flow to the desired rate. Because the procedure for
setting column flow rate depends on the column installed and the inlet
system used, refer to the appropriate inlet system information in
Chapter 4.
3.
Set the carrier and makeup gas flow rate (column plus makeup)
through the detector to at least 20 ml/min.
4. Attach a bubble flow meter to the FPD vent tube.
Your FPD makeup gas is equipped with either manual or electronic
pressure control. Set the makeup gas according to the instructions
below. To set capillary makeup gas flow rate:
Manual pressure control:
a. Set the supply pressure for the capillary makeup gas to about 276
kPa (40 psi).
b. Open the Aux gas on/off valve for the FPD makeup gas flow by
turning it counterclockwise.
164
—
Operating Detector Systems
Operating the flame photometric detector (FPD)
c. Use a small screwdriver to turn the variable restrictor at the center
of the Aux gas on/off valve as necessary to obtain 20 ml/min total
flow rate (column plus makeup).
Electronic pressure control:
a. Set the supply pressure to the auxiliary EPC channel to 60–70 psi
using the keyboard.
b. Open the Aux gas (makeup gas) on/off valve. Use the auxiliary EPC
pressure to control the auxiliary gas flow rate.
c.
Select the pressure units you would like to use.
number of the corresponding unit you want to use:
d. The example below sets the auxiliary channel C pressure to 10 psi.
I
EPP C
ACTUAL
SETPOINT
10.0
10.0
I
The GC display looks like this
Note: To keep the pressure constant through an oven ramp
program, see Chapter 10, Using Electronic Pressure Control.
e. Adjust the makeup gas pressure to the detector as necessary to
obtain 20 ml/min total flow rate (column plus makeup).
WARNING
To minimize risk of explosion when using a bubble flow meter, never
measure air and hydrogen together. Measure them separately.
5. Set the H2 flow rate to 75 ml/min. If you have a manually controlled
system, use the steps below. If you have EPC, enter the flow rate from
the keyboard as you did for makeup gas.
165
Operating Detector Systems
Operating the flame photometric detector (FPD)
a. Open the H2 on/off valve by turning it counterclockwise. Measure
the total flow rate (column plus makeup plus detector) through the
detector.
b. Adjust the H2 pressure to the detector to obtain a total flow rate
(column plus makeup plus H2) of about 95 ml/min.
c. Close the H2 on/off valve.
6. Use the following steps to set the air flow rate to 100 ml/min:
a. Open the air on/off valve by turning it counterclockwise and
measure the total flow rate (column plus makeup plus air) through
the detector.
b. Adjust the air pressure to the detector to obtain a total flow rate
(column plus makeup plus air) to 120 ml/min.
7. Remove the flow measuring adapter from the FPD collector.
8. Open the H2 on/off valve.
Turning the FPD on and off
After setting the flows, you can turn the FPD on or off.
Operating Detector Systems
Operating the flame photometric detector (FPD)
Igniting the FPD flame
WARNING
To minimize the risk of explosion, do not attempt to ignite the FPD flame
by applying a flame at its exhaust tube. Follow the procedure below.
Note: After the flows are set, the FPD flame is relatively easy to ignite.
The detector module is most easily lit if heated to at least 200°C. Use the
sequence described below to avoid a loud pop on ignition.
1. Turn all FPD flows (except the column flow) off
2. If required, open the auxiliary N 2 valve.
3. Open the air (or 02) valve.
4. Press in and hold the igniter button.
5. Open the H2 valve.
Note: Always open the hydrogen valve after opening the air (or 02)
and pressing the igniter. Failure to do this will result in a loud pop.
This should not damage the detector, but is unpleasant to hear.
6. Release the igniter button.
Proper ignition should result in a slightly audible pop. Flame ignition
can be verified by holding a mirror or a cold, shiny surface near the
exhaust tube and observing condensation. Ignition also usually results
in a small increase in signal offset on the LED display.
6
Controlling Signal Output
Controlling Signal Output
Signal Definition and Control
Output sources include detector signal(s), heated zone or oven
temperatures, carrier gas flow rates, column compensation run data, or
test chromatographic data. If both signal channels are present, each may
output information simultaneously from the same source, or from two
different sources.
Each channel provides two levels of analog output:
0 to +1 mV:
for strip chart recorders.
–0.01 to +1 V:
for electronic integrators with analog inputs.
The two output levels are independent and may be connected
simultaneously to separate data-receiving devices.
170
Controlling Signal Output
Assigning a signal
Note: A tick mark (electrical pulse) is produced at the +1 mV analog
or ( STOP
times out (run time elapses). These marks locate beginning and ending
points in a chromatogram plotted at a continuously running strip chart
recorder.
START
1
Assigning a signal
installed), any one of the instrument functions in the following table may
be entered to assign the signal to be output from the displayed channel.
Note that in a two-channel instrument it is permissible to have the same
signal assigned to each signal channel, allowing identical data to be treated
differently simultaneously.
171
Controlling Signal Output
Assigning a signal
Key(s)
Notes
To output the signal from either detector A or detector B
The message DET A (or B) NOT INSTALLED is displayed if detector A
(or B) is not present.
To output a difference signal between two detectors of the same type
The message DET A (or B) NOT INSTALLED is displayed
if detector A (or B) is not present; the message UNLIKE
DETECTORS is displayed if detectors A and B are not of
the same type.
To output a difference signal between a given detector and column and a
stored blank run signal for the detector and column
The message DET A (or B) NOT INSTALLED is displayed if detector A
(or B) is not present.
To output oven temperature
To output stored COMP 1 or COMP 2 data
To output, respectively, inletA temperature, inlet B temperature, detector A
temperature, or detector B temperature
To output, respectively, carrier gas flow rate A or B
To output a test signal (stored chromatogram) for use in verifying proper
operation of a data-receiving device (integrator, chart recorder, etc); details
are discussed later in this section.
172
Controlling Signal Output
Displaying or monitoring a signal
As an example, a key sequence to assign detector B data to the Signal 1
output channel would be:
At the same time, A flow rate data (if electronic sensing is installed could
be assigned to the Signal 2 output channel:
As an assignment is made for each channel, confirmation is given through
appropriate displays.
Displaying or monitoring a signal
of the corresponding signal channel is displayed.
Two types of displays are possible: either a display showing the
instrument function assigned to the particular signal channel or a display
monitoring the current actual output value for the assigned instrument
two possible display types.
Controlling Signal Output
Displaying or monitoring a signal
Typical Signal Displays:
Signal monitoring is useful, for example, in determining if an FID is
ignited, in setting active element current for an NPD, in determining
cleanliness of an ECD, in tracking temperatures or gas flow rates, etc. The
monitored value displayed is unaffected by scaling functions performed by
later).
If oven or heated zone temperature is monitored via the display the
conversion factor between the displayed value versus actual temperature is
64 counts/°C –200. Similarly if flow rate is monitored via the display, the
conversion factor is 32 counts/(ml/min).
174
Controlling Signal Output
Zeroing signal output
Zeroing signal output
available by subtracting a constant background signal from the detector
signal. Background signal sources include the detector itself (background
level depending upon detector type), column bleed, or contaminants in
supply gas(es). There are limits to this, however, so it is good practice to
reduce background as much as possible by minimizing column bleed by
using clean supply gases and by performing proper detector maintenance.
Typical displays are shown below.
ACTUIAL
Typical Zero Displays
signal value.
SETPOINT
Controlling Signal Output
Setting signal attenuation
Zeroing should be done only at times of quiet chromatographic activity
(i.e., not during a run). To do so during an active run may cause a baseline
shift at the recording/integrating device.
particular application, any value from –830000.0 through 830000.0 may
be entered at the keyboard.
baseline upward (but at the expense of available output range); for
example, to capture negative peaks or to compensate for negative baseline
drift.
Turning zero off/on
from the signal. Baseline is restored to its absolute level with respect to the
HP 5890 electrical zero.
resumes subtracting the offset value from the signal.
Setting signal attenuation
used to keep peaks of interest on scale at the integrator or chart recorder.
Peaks of interest must neither flat top by exceeding the allowed
maximum output level nor be too small to be measured.
signal source assigned to an output channel. The portion selected is sized
such that the highest possible value for the portion does not exceed
maximum output voltage allowed for the given output (+1 mV or +1 V).
Controlling Signal Output
Setting signal attenuation
+ 1 mV output to ensure that the signal does not exceed + 1 mV.
For electronic integrators (analog signal output +1 V): is attenuated
step to a higher setpoint value decreases the output signal level by a factor
of 2 (half the previous level).
As an example, a key sequence set attenuation and/or range would be:
The table below gives values permitted for either function, and the output
affected.
177
Controlling Signal Output
Setting signal attenuation
Key
Permitted
Setpoints
0 to13
Affected Output
BOTH +1 mV& +1 V
Generally if both an integrator or A/D converter (+ 1 V output) and chart
recorder (+1 mV output) are connected to the same signal channel,
To minimize integration error for an integrator or A/D converter,
the largest peaks of interest do not exceed 1 volt. Attenuation functions at
the integrating device or computer are then used to ensure that plotted
peaks remain on scale.
The table below lists maximum detector output producing +1 volt at the
178
Controlling Signal Output
Setting signal attenuation
Maximum Detector Signal Producing +1 V Output
FID & NPD (pA)
TCD (mV,
High Gain)
TCD (mV,
Low Gain)
ECD (kHz)
o
25
800
10
1
50
D
20
2
D
D
40
3
D
D
80
4
D
D
160
5
D
D
320
6
D
D
D
7
D
D
D
8
D
D
D
9
D
D
D
10
D
D
D
11
D
D
D
12
D
D
D
13
D
D
D
virtually all applications because the entire linear output range of the
the entire useful output range for an ECD. Only an FID or NPD may
Turning attenuation off/on
The +1 mV strip chart recorder signal output can be switched off,
providing no signal to the data-receiving device. This is often useful in
setting the zero position at a connected strip chart recorder.
Controlling Signal Output
Inverting TCD signal polarity
This is done through the following key sequence:
180
Controlling Signal Output
Using instrument network (INET)
Repeating the entry later in the run inverts polarity again to its original
state.
Polarity returns to its original state automatically at the end of the run.
Using instrument network (INET)
The “Instrument Network” (INET) is a path for various devices to
communicate with each other (data and/or commands). INET permits a
group of devices (consisting of a “controller” and some number of data
“Producers” and data “Consumers”) to function as a single, unified
system.
In using the INET function, chromatographic parameters are entered
normally through the HP 5890 keyboard. Integration parameters are
entered at the controller. Parameters for other devices on the INET loop
may be entered at the controller or at their own keyboards. Collectively,
the separate sets of parameters constitute a single set of parameters for an
“analysis.”
In DEFAULT operation, the HP 5890 supplies only “Signal 1“ data to the
INET loop. That is, HP 5890 data supplied to the INET loop is defined
instead, signal reassignment is done at the HP 5890.
As an example, a key sequence to assign detector B data to the Signal 1
output channel would be:
For more information about INET, refer to the HP 5890 SERIES II
Reference Manual and the reference manuals for your HP integrator/
controller.
7
Making a Run
Making a Run
This chapter includes information regarding starting and stopping an
analytical run, using timetable events, and making a single-column
compensation (SCC) run.
Starting/stopping a run
timed events.
Also, a remote start relay is momentarily closed to start a remote device
such as an integrator. For a strip chart recorder, a tick mark is produced to
mark the beginning of a run.
to follow progress through an oven temperature program. The red NOT
READY LED lights during a run only if some part of the system becomes
not ready (see Status LEDs on next page).
is produced to mark the end of a run.
184
Making a Run
Status LEDs
INET start/stop operation
Normally, when the HP 5890 SERIES II (hereafter referred to as HP 5890)
INET is turned OFF (LOCAL) at the HP 5890: if INET is off, HP 5890
controller. This permits starting the HP 5890 without simultaneously
starting the integrator/controller. (See the HP 5890 SERIES II Reference
Manual for details regarding switching INET on or off).
must be aborted at the HP 5890.
Status LEDs
Readiness occurs when the oven is on and at its setpoint temperature,
when heated zones that are on are at their respective setpoint
temperatures, and when any detector assigned to an output signal channel
is on.
Any temperature not at setpoint causes the red NOT READY LED to be lit
until setpoint is achieved.
In addition, there is an external readiness input, and an INET readiness
input. If a connected external device is not ready, the NOT READY LED is
lit.
If the NOT READY LED is continuously lit, any item(s) preventing
an appropriate message for each item.
Making a Run
Status LEDs
I CLEAR I Displays
ACTUAL
1
SETPOIN1
NOT READY
INJ A TEMP
1
ACTUAL
1
ACTUAL
I
DET A NOT ON
EXT DEVICE
I
IN
I
186
COMP 1 BLANK RUN
Assigned detector not
turned on
I
Device external to HP 5890
signals not ready
I
INIT system reports not
ready
I
Analytical run currently in
process
I
Column compensation run
currently in progress
SETPOINT
PROGRESS
ACTUAL
I
SETPOINT
NOT READY
SYSTEM
RUN
SETPOINT
NOT READY
ACTUAL
1“
I
(SIG 1)
ACTUAL
I
SETPOINT
NOT READY
DET A TEMP
Temperature not at
setpoint
SETPOINT
A
Making a Run
Status LEDs
Note that the figure above shows typical normal displays occurring when
various parts of a properly operating HP 5890 system are not ready for
initiating a run.
ACTUAL
I
HP 5880
SYSTEM
SETPOINT
READY
I
HP 5890 READY Display
For the oven and heated zones, their messages cease to be displayed once
their respective setpoint temperatures are reached. Once every item is
I
I
I
1
I
I
I
I
I
I
●
o
Status LED Display
LED on: indicates a run (either analytical or column compensation) is actively in progress.
LED off: indicates no run currently in progress.
I
L
I
LED on: One or more parts of the HP 5890 system reports not
LED off: HP 5890 system is ready for initiating a run (either analytical
or column compensation) at anytime.
Status LED Display (cont.)
The RUN LED is normally lit continuously whenever a run is in progress
(either an analytical or column compensation) and off when not in a run. It
flashes when a column compensation run is initiated before the HP 5890 is
ready (e.g., oven or zones not at setpoint); the compensation run begins
automatically upon readiness.
The RUN LED also flashes on and off in an INET-controlled system in
automated operation during times when the HP 5890 is waiting for some
device in the system to complete its task before starting the run (e.g., while
waiting for automatic sampler operation, report printing, computations,
etc). Once the run begins, the LED is continuously lit.
Using the time key
analyses being performed and also accesses a stopwatch timer useful in
setting gas flow rates, measuring elapsed time between events of interest,
etc.
188
Making a Run
Using the time key
Typical time displays are shown in the figure below. Note that there are
three possible functions outside an analytical run (or column
compensation run) and three possible during an analytical run (or column
ACTUAL
NEXT
RUN
24.38
ACTUAL
1/t=
t=5:l0.7
ACTUAL
I
I
During a Run:
1
LAST
RUN
15.77
ACTUAL
REMAINING
15.77
ACTUAL
I
t=
1:50.7
1/t=
ACTUAL
ELAPSED
12.15
SETPOINT
MIN
SETPOINT
0.19 I
SETPOINT
MIN I
SETPOINT
MIN |
SETPOINT
0.54 I
SETPOINT
MIN |
Typical Time Displays
Time displayed for NEXT RUN or LAST RUN does not include
and does not include cooldown time after completing an oven
temperature program. It is simply total time calculated for the analytical
(or column compensation run) itself.
In stopwatch mode, both time (to 0.1 second) and reciprocal time (to
0.01 rein-l) are displayed simultaneously. The timer is started by pressing
timer is stopped resets the timer.
189
Making a Run
Using single-column compensation
Note that other instrument functions may be accessed normally (e.g.,
pressing the necessary keys. The timer continues to run but is not
analytical run (see Using timetable events in this chapter).
Using single-column compensation
The HP 5890 permits performing a chromatographic blank run (run
made with no sample injected), storing the data as a baseline profile.
Assuming the baseline profile is consistent from run to run, it maybe
subtracted from sample run data to remove baseline drift (usually caused
by column bleed).
Note: Single-column compensation data is valid only for a specific
detector and column combination operating under defined temperature
and gas flow rate conditions. Invalid results may occur if conditions by
which blank run data is collected are different from conditions used to
collect sample run data.
profiles for the same detector but using different chromatographic
conditions.
compensation run if the run must be aborted at the HP 5890.
190
Making a Run
Using single-column compensation
Displaying column compensation status
Status of column compensation data is displayed by pressing either
The figure below gives typical displays:
ACTUAL
I
COMP 1
-
NO
I
COMP 1
-
DATA
DATA
SETPOINT
ACTUAL
OK
I
1|1
Valid baseline profile data is presently
stored for detector A in COMP 1.
SETPOINT
COMP 1
TOO
A
COMP 1
WRONG TIME A
ACTUAL
I
No baseline profile data is presently
stored for detector A in COMP 1.
SETPOINT
A
ACTUAL
STEEP
1
A
I
Change in baseline slope exceeds
maximum value permitted.
Column compensation data may
not be valid.
I
Column compensation run aborted
SETPOINT
Column compensation data may
not be valid.
(Equivalent displays are possible for COMP 2 and/or detector B)
Typical Column Compensation Status Displays
191
Making a Run
Using single-column compensation
Initiating a column compensation run
After entering the oven temperature program to be used for later sample
runs, a column compensation run is initiated by first pressing either
to display current column compensation status
and to designate where the new baseline profile is to be stored.
. If the desired detector (A or B) is displayed, the column compensation
. If the wrong detector is displayed, press either A or B to assign the
compensation run.
runs using the same oven temperature program and storing a baseline
profile for each of the assigned detectors simultaneously.
This option is useful for sample analyses made using different detectors
and/or columns but using identical temperature programs.
Note: A device connected via the remote start/HP 5890 ready cable that is
started from the HP 5890 by a normal analytical run is not started by a
column compensation run.
Additional detail concerning functions available at the REMOTE receptacle
is found in the HP 5890 SERIES II Site Prep and Installation Manual.
Messages listed in the next figure are displayed either while a column
compensation run is in progress or if there is a problem preventing the
compensation run from starting.
192
Making a Run
Using single-column compensation
ACTUAL
|
COMP 1
I
INVALID
BLANK
RUN
SETPOINT
A
ACTUAL
DURING
ACTUAL
I
NO
TEMP
PROGRAM
Or detector B, chosen detector not switched
on. No column compensation run is performed.
DET A NOT ON
DET A
NOT
SETPOINT
INSTALLED
ACTUAL
I
NO
DETECTOR
INVALID IN
FOUND
COMP
I
Or detector B, chosen detector not present.
No column compensation run is performed.
I
No detector(s) present. No column compensation run is performed.
|
Occurs if entering new oven temperature
program setpoints is attempted during a
column compensation run. Entries are
ignored. Also occurs if an attempt is made
to start a column compensation run while
one is already in progress. The one in progress continues to normal completion.
SETPOINT
ACTUAL
I
I
An oven temperature program is not defined:
setpoint value(s) must be
entered. The temperature program defined
should be that used for sample runs. No
column compensation run is performed.
SETPOINT
ACTUAL
I
1
The oven is not on. Once the oven is
switched on, the column compensation run
begins automatically when the oven is equilibrated at its initial temperature setpoint.
SETPOINT
ACTUAL
I
Displayed if an attempt to start a column
compensation run is made while a sample
run is in progress. No column compensation run is performed.
SETPOINT
OVEN NOT ON
Comp run in progress. In this example, data
from detector A is stored as COMP 1
|
SETPOINT
RUN
ACTUAL
|
|
SETPOlNT
RUN
Typical Column Compensation Message Displays
193
Making a Run
Using single-column compensation
A column compensation run terminates automatically at completion of its
oven temperature program. Any existing baseline profile is erased as data
for the new baseline profile is collected and stored.
Note that the oven temperature program for a column compensation run
INIT TIME
FINAL TIME
portions of the temperature program.
baseline profile stored is probably not valid because the oven temperature
setpoint. A message
WRONG TIME is displayed to indicate a mismatch has occurred between
the expected length of time for the run versus the actual time.
Assigning column compensation data
After baseline data for a given detector (A or B) is stored as either COMP 1
or COMP 2, the column compensation data must be assigned to a specific
detector signal. During a run, the compensation data is subtracted from
run data for the same detector.
The following key sequence assigns such baseline-corrected data to a
particular output channel:
194
Making a Run
Using instrument network (INET)
The figure below illustrates the resulting display confirming the
assignment:
Column Compensation, Typical Display
Note: There is no internal verification by the HP 5890 to ensure that
compensation data collected on a given detector is later assigned to be
subtracted from the same detector via the above key sequence. If
subtracting compensation data results in strange baseline behavior:
. Compensation data itself is suspected.
. Data acquired from a different detector has been assigned.
● Chromatographic
conditions used for sample analyses are different
from those used for the original column compensation run.
Once assignment is made to a particular output channel, sample analyses
are performed in the usual manner; the only difference is that the
observed baseline should be relatively free of drift.
Using instrument network (INET)
Information about INET communications is available in Chapter 6,
Controlling Signal Output and in the reference manuals for your
integrator/controller.
195
Making a Run
Using timetable events
Using timetable events
Timetable events are controlled through the keys shown.
b
-
-
-
-
-
-
-
*
Timetable Control Keys
The following is a list of HP 5890 events that can be controlled during a
run.
●
Valves (On/Off)
●
Signal Switching (On/Off)
●
Changing TCD Sensitivity (High or Low)
●
Inverting TCD Polarity (-) Refer to Chapter 6, Inverting TCD
signal polarity
●
Split/Splitless Purge Flow On/Off Refer to Chapter 4, Setting
splitless mode flow
Making a Run
Using timetable events
Valves, signal switching and changing TCD sensitivity are covered in this
section. Refer to Chapter 6 for information regarding inverting TCD
polarity during a run. Refer to Chapter 4 for information regarding
turning split/splitless flow on/off during a run.
ACTUAL SETPOINT
Use the table key to enter into the timetable. From .
here, previous and next keys may be used to scroll
through an existing timetable. Add and delete keys
may be used to add or delete timetable commands.
After the TABLE kev is pressed to enter the
timetable, use the ADD key to enter a timed
event. The timetable can hold up to 37
timed events.
After the TABLE key is pressed to enter
the timetable, use the DELETE key to
remove a timed event.
cAfter the TABLE key is pressed to enter
PREVIOUS
the timetable, use the PREVIOUS key to
scroll through the timetable toward the
HEAD OF TIMETABLE.
After the TABLE key is pressed to enter
the timetable, use the NEXT key to scroll through the timetable toward the END OF
TIMETABLE.
whenever working inside the timetable) use the
CLEAR key to exit timetable programming.
Note: The clear key does not delete any timetable events.
197
Making a Run
Using timetable events
An example key sequence to create a timetable event:
Valve 1,2,3 or 4 )
Note: Refer to “Inverting TCD Signal Polarity” in Chapter 6 for time programming TCD polarity.
Turning valves on/off during a run
For information on controlling splitless purge flow during a run, refer to
Chapter 4, Setting splitless mode flow.
Control of up to four gas/liquid sampling valves (designated as valve 1,2,3,
and 4) may occur in either of two ways. The operator may switch the
valves manually whenever it is desirable via keyboard entry, or more
conveniently, the valves can be switched on and off during a run via the
HP 5890’s timed events table.
198
Making a Run
Using timetable events
For example, to create a timetable event to turn valve 2 on at 1 minute
into a run, enter the key sequence:
Note: If the valve is already in the position where a command instructs it
to switch, no action will occur.
The designated channels (1, 2, 3, or 4) are determined solely by the wiring
connections to the valve box.
A valve will reset automatically at the end of each run if a valve timetable
is set. If the last switching mispositioned the valve and the valve does not
reset, reset the valve position manually before starting a new run.
One way of resetting the valve automatically after the useful run time is to
program the valve.
For example, on a two-valve system, where valve 1 is a gas sampling valve
and valve 2 is used for venting, it may be desirable to: 1) inject from valve
1 at the beginning of the run (run time 0.00); 2) vent the last part of the
sample, using valve 2, at 2-3/4 minutes (run time 2.75); or 3) relax both
valves just prior to the end of the run (determined to be a run time of
40.00).
To perform the above example, enter the following commands:
Making a Run
Using timetable events
Switching signals during a run
Some analyses require the use of more than one detector to completely
characterize a given sample. In situations were the analytical system can
be configured to avoid coelution, switch signals during a run to integrate
the output into a single channel system. Signal switching can be accessed
only as a timetable event.
Signal Switch On Time
Signal Switch Off Time
Making a Run
Using timetable events
For example, to create a timetable event to switch signals at 1 minute into
a run, enter the key sequence:
manner until a signal switch off time is reached or the run ends. Signal
assignments reset automatically at the end of each run.
Depending on the analyses, baseline upsets maybe seen when signals are
switched. These upsets will become more of a problem when high
necessary to minimize the upset.
Changing TCD sensitivity during a run
Two TCD sensitivity (signal amplification) settings are available,
The high-sensitivity setting increases sensitivity (area counts observed) by
a factor of 32 and is usable in applications where component
concentrations are < 10%.
Components that are more concentrated may exceed the output range for
the TCD, causing flat-topped peaks. If this occurs, the low sensitivity
setting should be used instead.
The sensitivity setting may be changed from one setting to the other at
any time during a run through a timetable event.
201
Making a Run
Using timetable events
For example, to create a timetable event to change the TCD sensitivity
from Low to Hi at 1 minute into a run:
Sensitivity returns to its original state automatically at the end of the run.
Modifying timetable events
|
I
FUNCTION
VALVE 1 ON
1
, TIME ,
1.00
Example Timetable Event
Timetable events can be changed in three ways: by adding new entries, by
deleting existing entries or by modifying the time value of a timed event.
New entries are added by using the same key sequences used to create a
table in the first place:
To delete a single timetable event, first display the event by pressing:
202
Making a Run
Using timetable events
While the particular event is displayed, delete the event from the timetable
by pressing:
The instrument will respond, DELETED.
To modify the time associated with an event, first display the event by
pressing:
To modify the time press:
respond, MODIFIED.
For example, to change VALVE 1 ON 1.00 to VALVE 1 ON 2.00, (while
VALVE 1 ON 1.00 is displayed) the key sequence is:
The result is valve 1 will turn on at 2 minutes rather than 1 minute.
8
Storing and Loading
HP 5890 Series 11 Setpoints
Storing and Loading HP 5890
Series II Setpoints
Up to two sets of GC setpoints may be stored in the HP 5890 Series II
(hereafter referred to as HP 5890). GC setpoints include any entry made
through the HP 5890 keyboard. These sets of GC setpoints are stored in
storage registers designated as 1 or 2.
Storing GC setpoints
To store a set of setpoints currently in the HP 5890 into a storage register,
use the following key sequence:
register 1 or 2
Storing and Loading HP 5890 Series II Setpoints
Loading GC setpoints
Loading GC setpoints
WARNING
Be careful when loading GC setpoints from a storage register. Stored
setpoints may turn detectors on or set high oven temperatures which,
without proper gas flow, could damage a detector or column.
To load a set of setpoints already stored in one of the storage registers, the
key sequence is:
register 1 or 2
Loading setpoints replaces all the setpoints currently defined in the
HP 5890 with the setpoints in the storage register selected.
As a guide to recording GC setpoints stored in storage registers, the
following pages may be photocopied and used to record a list of setpoints
before they are stored. Keep these lists for your records when preparing to
load setpoints.
207
Storing and Loading HP 5890 Series II Setpoints
Loading GC setpoints
Storage Setpoint Log
208
Storing and Loading HP 5890 Series II Setpoints
Loading GC setpoints
Storage Setpoint Log (continued)
209
Storing and Loading HP 5890 Series II Setpoints
Loading GC setpoints
Time Table Events:
Storage Setpoint Log (continued)
210
9
Controlling Valves
Controlling Valves
Control of up to four valves (designated as valve 1,2,3, and 4) may be
accomplished in two ways.
. During a run (see Chapter 7, Turning valves on/off during a run)
. Manually through keyboard entry as described in this chapter
Note: If the valve is already in the position where a command instructs it
to switch, no action will occur.
The following figure illustrates some examples of the HP 5890 SERIES II
(hereafter referred to as HP 5890) alphanumeric display for listing current
valve status or verifying the timed events table to switch the valve during
a run.
Typical Valve Status Displays
212
Controlling Valves
Turning valves on/off manually
Turning valves on/off manually
The designated channels (1, 2, 3, or 4) are determined solely by the wiring
connections to the valve box. However, often valves will be located as
shown in the figure below.
I
r — — — — — l
Controlling Valves
Turning valves on/off manually
Valves may be switched from the keyboard at any time by pressing the key
sequence:
c
PURGE/VALVE
a
r
e
a
=
To display the current status of a valve, press:
Valve 1,2,3 or 4
If the HP 5890 display is already displaying the appropriate addressed
valve, the operator need only press the ON or OFF key to activate or relax
the displayed valve.
A valve resets automatically at the end of each run. If the last switching
mispositioned the valve for the start of the next run, the valve position will
reset at the end of the run.
214
10
Using Electronic
Pressure Control
Using Electronic Pressure Control
What is electronic pressure control?
The electronic pressure control (EPC) option for the HP 5890 Series II
Plus GC allows you to control the inlet and auxiliary gases from the
keyboard.
You access the inlet and auxiliary detector gases by pressing one of the key
sequences shown in the following table. The keys you press depend on how
your GC is configured. For example, if auxiliary channel C is programmed
to control the makeup gas for detector A, you would access the auxiliary
EPC channel C to access control of that gas.
I
EPC Controls Inlet Gas
–1
With EPC, inlet and detector pressures can be either constant or
programmed. The following sections describe the benefits of using EPC for
inlets and detectors.
216
Using Electronic Pressure Control
What is electronic pressure control?
Using electronic pressure control with inlets (EPC)
EPC of inlets provides very accurate and precise control of column head
pressure, typically resulting in retention time reproducibility of better
than 0.02% RSD when no column effects are present. With EPC, you can
set constant pressure and pressure programs through the keyboard. Inlet
pressures can also be set to maintain a desired column flow rate when the
column parameters have been entered.
Using electronic pressure control with detectors (auxiliary EPC)
Auxiliary EPC allows you to control detector gases electronically. With
auxiliary EPC, you can set constant pressure and pressure programs
through the keyboard. Auxiliary EPC is provided by the combination of
new, electronically controlled flow modules for gases and the PC board
capability to control those modules.
Auxiliary EPC of detector gases allows you to program the makeup gas to
optimize a detector’s performance. With auxiliary EPC, you can control:
● All
detector gases, including makeup, carrier, and fuel gases
. Gas flow to an external sampling device, such as a purge and trap or
headspace system
. Gas flow through the split vent of a split/splitless inlet, which can save
gas and optimize the operation of the inlet (see Operating the Gas
Saver for the Split/Splitless Inlet in this chapter)
217
Using Electronic Pressure Control
What is electronic pressure control?
The following table shows the multiple uses of EPC for inlets and auxiliary
EPC for detectors:
Uses for EPC and Auxiliary EPC
EPC
Head Space
Purge and Trap
●
●
●
●
●
●
●
Gas Saver
Thermal Resorption
Auxillarv EPC
Note: All HP 5890 instruments built before July 1, 1990, will display the
message Change EPC ROM when used with EPC. When this occurs,
contact a Hewlett-Packard service representative to upgrade and install
the new ROM.
For additional EPC information, see the HP application note Analysis of
Oxygenates in Gasoline, Including ETBE and TAME, Using Dual-Channel
Electronic Pressure Control, HP Application Note 228-174, publication no.
(43) 5091-4701E.
This chapter is divided into several sections, including general EPC
instructions, optimization information for inlets, and optimization
information for detectors. Specifically, this chapter provides operating and
optimization information for the following EPC systems:
. Split/splitless capillary inlet with EPC
. Septum purged packed Inlet with EPC
. Auxiliary EPC of detector gases
● Auxiliary
EPC with Gas Saver for the split/splitless inlet
. Auxiliary EPC with external sampling devices
218
Using Electronic Pressure Control
What is electronic pressure control?
Operating information for the programmable cool on-column inlet is
provided in a separate manual included with the manual set. The following
table describes the features that are available for specific uses and
applications of EPC:
Features of Electronic Pressure Control
Constant Pressure
Pressure
Controlled Function Pressure Programs
Vacuum
Flow**
Set Avg.
Set Mass
Constant
Flow Mode Flow Rate Programs Linear Velocity Comp.*
Split /Splitless Cap.
Inlet (Carrier Gas)
●
0
●
●
●
●
●
Septum PP
Inlet (Carrier Gas)
●
0
●
●
●
●
●
Programmable
Cool On-Column Inlet
●
0
●
●
●
●
●
Auxiliary EPC
(Detector Gas)
●
0
Auxiliary EPC
(Gas Saver)
●
0
Auxiliary EPC
(General Purpose)
●
0
*Auxiliary inlet channel will calculate the vacuum compensation.
**You enter the required pressures.
Note: Constant flow mode is recommended for use with 530µ capillary
columns. For packed columns, you must calibrate for each individual
column to correct for different column lengths and possible settling of the
column packing.
219
Using Electronic Pressure Control
Safety shutdown for electronic pressure control
Safety shutdown for electronic pressure control
Systems equipped with EPC have a safety shutdown feature to prevent gas
leaks from creating a safety hazard. The safety shutdown feature is
designed to prevent an explosive concentration of hydrogen carrier gas
from accumulating in the GC oven if a column breaks.
Back pressure regulated inlet systems (split/splitless capillary inlet) with
EPC cannot detect a column leak, however, because a column leak would
occur before the gas reaches the EPC valve. These systems limit the leak
rate into the oven using the total flow controller. Under these conditions,
hydrogen diffusion out of the oven is fast enough to keep hydrogen
concentration below the 4.l% lower explosion limit.
What happens during electronic pressure control safety shutdown?
If the system cannot reach a pressure setpoint, the system beeps. After
about 2 minutes, the beeping stops and the following message appears on
the display:
ACTUAL
I
SETPOINT
EPP B SAFETY SHUTDOWN
I
The system shuts down by entering a pressure setpoint of zero for the
affected channel, turning off all heated zones, and locking the keyboard.
The table on the following page summarizes the safety shutdown.
220
Using Electronic Pressure Control
Summary table of safety shutdown
Summary table of safety shutdown
What channels can shut down?
The system can shut down all inlet and auxiliary channels.
When does the system start
beeping?
The beeps start 10 seconds after the pressure falls below
0.1 psi of setpoint.
What is the frequency of the
beeping?
The system beeps at 10,40,60,70,79,87,94, 100,105,
109, 112,114, 115,116,117, 118,119, and 120 seconds.
When does the system stop
beeping?
The beeps stop 120 seconds after the system falls short of
the setpoint pressure. The actual safety shutdown begins.
What happens after the safety
shutdown occurs?
1. The keyboard locks.
2. All heated zones are turned off.
3. The oven fan is turned off.
4. The GC display shows the shutdown message.
5. The other pressure setpoints do not change.
6. The setpoint of the affected EPC channel is set to 0.0.
Note: These safety shutdown procedures apply to EPC boards with a
mainboard ROM of HP part number 05890-80310 or higher.
221
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
Setting inlet pressure using electronic pressure control
If your GC is equipped with EPC, you can set constant pressure or create a
pressure program with multiple ramps. The following procedures will
show you how to:
. Zero the pressure sensor in all channels and repressurize the system
. Set and maintain a constant pressure
● Set
a pressure program using one or two ramps
● Check
your pressure program
For more information on setting inlet pressures, see Chapter 4, Setting
Inlet Pressure.
Zeroing the pressure
The EPC system is zeroed before shipping, but you should check it
periodically especially when ambient laboratory conditions change
dramatically Zero the instrument 30 to 60 minutes after the system has
heated up to allow for electronic drift.
To zero an EPC channel:
1. Turn off the inlet and detector gases. With zero pressure, remove the
inlet septa and repressurize the inlet.
Note: If the detector gas valves are closed, you will not be able to
repressurize the system.
Note: When EPC is part of a GC-MS system, zero the pressure when
either the MS pump is off or the column is not connected to the inlet.
Otherwise, the vacuum pump will lead to miscalibration.
222
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
2. Use the steps below to zero channels A through F:
Allow enough time for the column to completely depressurize.
where value is the zero offset value shown on the GC display
labeled “actual.”
where value is the zero offset value shown on the GC display
labeled “actual.”
Allow enough time for the system to repressurize completely.
where value is the zero offset value shown on the GC display
labeled “actual.”
223
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
●
To zero channel D:
Sets channel D pressure to 0.0
Allow enough time for the system to repressurize completely.
where value is the zero offset value shown on the GC display
labeled “actual.”
. To zero channel E:
Sets channel E pressure to 0.0
Allow enough time for the system to repressurize completely.
where value is the zero offset value shown on the GC display
labeled “actual.”
. To zero channel F:
Sets channel F pressure to 0.0
Allow enough time for the system to repressurize completely.
where value is the zero offset value shown on the GC display
labeled “actual.”
224
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
Setting constant flow mode
While using constant flow mode, the pressure will change if the oven
temperature changes to keep the flow constant. When you select constant
flow, you can set an initial pressure (at oven initial temperature) and the
GC maintains the initial flow throughout the run by adjusting pressure
continuously and automatically. This example shows how to set the inlet B
pressure at 10 psi.
1. Use the following steps to turn on the constant flow mode:
until you see the constant flow display.
ACTUAL
|
[
EPP B CONST FLOW OFF
EPP B
B: INIT TIME
I
ACTUAL
SETPOINT
10.0
10.0
ACTUAL
I
SETPOINT
650.00
I
The GC display looks like this
|
The GC display looks like this
SETPOlNT
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
15 psi
10 psi
Inlet B at Constant Pressure
Note: Inlet B will stay at 10 psi until the oven temperature changes. Then
the pressure will increase to keep the flow constant.
Setting inlet pressure programs
The run time of the analysis is determined by the oven temperature
program. If the inlet pressure program is shorter than the oven
temperature program, the inlet pressure does not remain at the last value
but goes into constant flow mode for the remainder of the run. If the oven
temperature is changing, then the pressure will also change. To prevent a
pressure program from going into constant flow mode, set the pressure
program longer than the oven temperature program.
The following procedure shows how to create a pressure program with
three pressure ramps for inlet B.
1. Turn the constant flow mode off.
Note: For more information on setting constant flow mode, see Using
constant mass flow mode for inlets later in this chapter.
226
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
2. Use the following steps to program the first pressure ramp:
The first pressure ramp starts at 10 psi for 1 minute, then ramps at 5
psi/rein to 20 psi and remains there for 2 minutes.
The first pressure ramp starts at 10 psi for 1 minute, then ramps at 5
psi/rein to 20 psi and remains there for 2 minutes.
3. Use the following steps to program the second pressure ramp:
The second pressure ramp starts at 20 psi and ramps at 2 psi/rein to 26
psi. It remains at 26 psi for 2 minutes.
227
to 30
The following graph shows the entire three-ramp pressure program.
30 psi
25 psi
20 psi
15 psi
10 psi
O psi
0
1
2
3
4
5
6
Inlet B with 3 Pressure Ramps
228
7
Minutes
8
9
10
11
12
13
Using Electronic Pressure Control
Setting inlet pressure using electronic pressure control
Checking inlet pressure programs
1. Display the pressure program by pressing any pressure program key
program.
Note: The oven program determines the run time of the analysis. If the
inlet pressure program is shorter than the oven temperature program, the
inlet pressure goes into constant flow mode for the remainder of the run.
To prevent this, make sure that the inlet pressure program is equal to or
longer than the oven program.
Pressure
End of Pressure
Program
Init
Value
Time
Constant
Flow Mode
Final
Time
Run Time
Pressure Program
End of Oven
Program
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
Setting pressure using auxiliary electronic pressure control
Auxiliary EPC is generally used for applications other than the control of
carrier gas to the column. The auxiliary channels (labeled C through F) do
not use the pressure versus flow calculations that the inlet channels have.
Only pressure setpoints and programs are entered, with flow values
determined from the calibration curves established.
For applications such as detector gas control, where the restriction is
provided mainly by a flow restrictor in the detector block, the calibration
curves are described by the following equation:
F = kx P
M
Note: This is the equation used by the HP 3365 ChemStation for pressure
versus flow calculations with the auxiliary EPC channels. Values for the
constants k and M are displayed on the auxiliary pressure programs screen
of the ChemStation when the calculations are carried out. For term
definitions, see your ChemStation manual.
How do I access auxiliary electronic pressure control?
To access the auxiliary EPC channels, use the following keys at the GC
keyboard:
230
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
Caution
The pressure that you program at the keyboard is the pressure the HP
3365 ChemStation uses in its calculations. When operating under low
pressure, such as 15 psi, be sure to program the same pressure (15 psi)
at the keyboard. If the rate entered at the keyboard is higher, the
ChemStation will base its calculations on that rate, which may not be
the accurate flow through your system.
Setting constant detector pressure
This example shows how to set the auxiliary EPC channel C pressure at 10
psi. For additional operating information, see Chapter 5, Operating
Detector Systems.
Sets auxiliary EPC channel C pressure to I0 psi
ACTUAL
SETPOINT
10.0
I
EPP C
10.0
I
C: INIT TIME
650.00
The GC display looks like this
1
I
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
20 psi
15 psi
10 psi
O psi
I
I
I
Sets the ramp rate at 5 psi/min
232
I
I
I
I
I
I
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
2. Use the following steps to program the second pressure ramp:
The second pressure ramp starts at 20 psi and ramps at 2 psi/min to 26
psi. It remains at 26 psi for 2 minutes.
Sets the second ramp rate at 2 psi/min
3. Use the following steps to program the third pressure ramp:
233
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
The following graph shows the entire three-ramp pressure program.
Auxiliary EPC Channel C
with Three Pressure Ramps
30 psi
25 psi
20 psi
15 psi
10 psi
O psi
O
1
2
3
4
5
6
7
8
9
Minutes
10
11
12
13
Checking Detector Pressure Programs
through and view the program immediately after setting it.
Suggested ranges for operating auxiliary electronic pressure control
The following graphs show the ranges that Hewlett-Packard suggests to
optimize the operation of auxiliary EPC for detectors. The graphs show the
flow restrictor you will need (the restrictors are identified by colored dots)
and the corresponding pressure versus flow relationship. Use the table
that most closely corresponds to the gas type you will use in your analysis.
234
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
Auxiliary EPC Restrictor Kit
19234-60600 Green and Brown Dot
Computed nominal values at ambient temperature of 21°C and pressure of 14.56 psia
Pressure
(kPa)
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
Pressure
(psig)
Helium Flow
(ml/min)
10
20
30
40
50
60
70
80
90
100
Nitrogen Flow
(ml/min)
20
45
76
111
150
190
232
275
321
22
50
87
131
182
239
300
366
437
513
Hydrogen
Flow (ml/min)
Air Flow
(ml/min)
42
99
170
251
344
442
549
666
786
901
Argon/Meth
Flow (ml/min)
19
40
65
95
128
164
202
242
282
324
21
45
76
110
148
188
229
273
318
363
700
600
500
Flow
ml/min
400
300
200
100
0
‘o
20
40
60
Pressure, psig
Flow Restrictor Data 19234-60600
80
100
120
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
Auxiliary EPC Restrictor Kit
19231-60610 Brown Dot
Computed nominal values at ambient temperature of 21°C and pressure of 14.56 psia
Pressure
(kPa)
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
Pressure
(psig)
Helium Flow Nitrogen Flow Hydrogen
(ml/min)
(ml/min)
Flow (ml/min)
10
20
30
40
50
60
70
80
90
100
76
174
302
457
634
838
1063
1310
1580
1873
61
161
279
418
571
740
915
1101
1297
Air Flow
(ml/min)
150
344
596
896
1243
1634
2035
2456
2918
Argon/Meth
Flow (ml/min)
65
157
273
410
561
726
900
1084
1278
1470
55
134
235
352
485
627
782
945
1110
1270
1200
1000
800
Flow
ml/min
600
400
120
0|
o
I
I
I
20
40
60
Pressure, psig
Flow Restrictor Data 19231-60610
236
I
80
I
100
120
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
Auxiliary EPC Restrictor Kit
19243-60540 Green and Red Dot
Computed nominal values at ambient temperature of 21°C and pressure of 14.56 psia
Pressure
(kPa)
Pressure
(psig)
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
10
20
30
40
50
60
70
80
90
100
Helium Flow
(ml/min)
7.2
17
29
44
61
80
100
124
150
178
Nitrogen Flow
(ml/min)
6.4
15
26
39
53
69
86
104
123
143
Hydrogen
Air Flow
Flow (ml/min) (ml/min)
14.7
35
59
88
122
159
200
243
290
339
6.2
15
25
38
52
67
84
101
120
139
Argon/Meth
Flow (ml/min)
5.7
13
22
33
46
59
74
89
106
123
Using Electronic Pressure Control
Setting pressure using auxiliary electronic pressure control
Auxiliary EPC Restrictor Kit
19234-60660 Blue Dot
Computed nominal values at ambient temperature of 21°C and pressure of 14.56 psia
Pressure
(kPa)
Pressure
(psig)
69.0
137.9
206.8
275.8
344.7
413.7
482.6
551.6
620.5
689.5
10
20
30
40
50
60
70
80
90
100
Helium Flow Nitrogen Flow
(ml/min)
(ml/min)
1.0
2.1
3.6
5.4
7.4
9.7
12.3
15.2
18.3
22.0
1.3
2.7
4.4
6.4
8.8
11.5
14.5
17.7
21.2
24.9
Hydrogen
Flow (ml/min)
Argon/Meth
Flow (ml/min)
Air Flow
(ml/min)
2.0
4.6
8.1
12.3
16.9
22.2
27.9
34.5
41.5
49.7
0.9
2.0
3.4
5.0
7.0
9.2
11.7
14.5
17.5
20.6
/
/
0.9
1.9
3.2
4.8
6.4
8.4
10.5
12.9
15.5
18.4
25
20
I
I
/ /
Flow
ml/min
20
40
Flow Restrictor Data 19234-60660
238
60
Pressure, psig
80
100
120
Using Electronic Pressure Control
Using electronic pressure control to control gas flow
Using electronic pressure control to control gas flow
With EPC you can also control flow by setting the pressure. The following
procedures will show you how to:
. Access the flow parameter displays
●
Select the gas type
. Set the column diameter
. Set the column length
. Use the vacuum compensation mode
. Set constant mode for inlets
●
Set mass flow rate for inlets
Pressure is the parameter controlled and measured with the EPC system;
however, the corresponding column outlet flow rate and average linear
velocity are also calculated and displayed. Entries can be made in terms of
velocity from which the system calculates the required pressure and enters
this setpoint
The following example shows the relationship between pressure and flow
for EPC systems. In the first table, pressure is constant and the flow
changes with temperature. In the second table, flow is constant and
pressure changes with temperature.
Using Electronic Pressure Control
Using electronic pressure control to control gas flow
Constant Pressure with Changing Flow
Temperature (°C)
Flow (ml/min)
50
100
3.6
200
150
2.8
2.3
300
250
1.9
1.6
1.3
Pressure (psi)
15
15
15
15
15
15
Linear Velocity (cm/see)
51.1
46.3
42.4
39.1
36.2
33.7
200
250
300
Constant Flow with Changing Pressure
Temperature (°C)
Flow (ml/min)
240
50
3.6
100
3.6
150
3.6
3.6
3.6
3.6
Pressure (psi)
15
18
21.9
24
27.1
30.2
Linear Velocity (cm/see)
51.1
55.1
58.3
60.9
63.1
65.0
Using Electronic Pressure Control
Accessing the flow parameter displays
Accessing the flow parameter displays
Use the following steps to access and scroll through the GC flow
parameters displays.
displays. The displays may be in a different sequence depending on
your configuration.
ACTUAL
EPP B
He
[1]
ACTUAL
EPP B
B:
I
B:
I
B:
ACTUAL
1
Use this display to turn the vacuum
compensation mode on or off.
I
Use this display to set the column
diameter
|
Use this display to set the column length.
I
Use this display to set the mass flow rate.
SETPOINT
Column Len 10.00 M
Split
Use this display to change the gas type.
SETPOINT
Column Dia .530 mm
ACTUAL
I
setpoint
VAC COMP OFF
ACTUAL
|
SETPOINT
setpoint
O Ml/Min
Flow Parameter Displays
241
Using Electronic Pressure Control
Selecting the gas type
Selecting the gas type
You will need to selector verify the gas type you are using for EPC
applications. To select the gas type:
display.
ACTUAL
I
EPP B
He
setpoint
[1]
I
The GC display now looks like this.
3. Press the number corresponding to the gas type you want to use. The
chart below lists the gas types available:
Gas Type
The number and gas you select will appear under the" setpoint"
column on the GC display:
The GC display now looks like this.
242
Using Electronic Pressure Control
Setting the column diameter
Setting the column diameter
To set the column diameter:
see the column diameter display.
ACTUAL
B
SETPOINT
.XXX m m
Column DIA
I
The GC display looks like this.
3. Enter the column diameter in µ (such as 200 µ, 320 µ, 530 µ). The
example below shows the column diameter for a 530 µ column.
Sets the column diameter to 530 µ.
ACTUAl
|
B:
Column Dia
SETPOlNT
.530 mm
|
The GC display looks like this.
Setting the column length
If you do not know the exact column length or if you are using a packed
column, follow the steps described in Determining the corrected column
length later in this chapter. To set the known column length in meters:
1.
2.
ACTUAL
I
3.
B:
SETPOlNT
Column Len XX.XXM
I
The GC display looks like this.
Enter the column length in meters.
243
Using Electronic Pressure Control
Using vacuum compensation mode
Using vacuum compensation mode
Use vacuum compensation mode when you are using a mass spectrometer
to correct for the column outlet pressure. Using the vacuum compensation
mode ensures that the constant flow mode, calculated column flow, and
average linear velocity are correct.
display.
ACTUAL
I
EPP B VAC COMP OFF
setpoint
I
The GC display looks like this.
3. Use one of the following steps to turn the vacuum compensation mode
on or off:
a.
mode on.
After you select vacuum compensation, set the desired pressure.
For more information on setting the inlet pressure, see Setting inlet
pressure using electronic pressure control earlier in this chapter.
b.
244
Using Electronic Pressure Control
Using constant flow mode for inlets
Using constant flow mode for inlets
Before setting the constant flow mode for inlets, you must first select the
gas type. See Selecting the gas type earlier in this chapter for more
information.
Note: The initial pressure changes when you turn the constant flow mode
on or off. Enter the desired initial pressure after selecting constant flow
mode. Also, make sure that the oven is equilibrated to the initial
temperature. If you set the initial pressure before the oven reaches the
initial oven temperature, the flow will be incorrect.
To use constant mass flow mode:
until you see the constant flow display.
ACTUAL
I
setpoint
EPP B CONST FLOW OFF
I
3. Use one of the following steps to turn the constant flow mode on or off:
When you select on, you can set an initial pressure (at oven initial
temperature) and the GC maintains the initial flow throughout the
run by adjusting pressure continuously and automatically.
You must select off if you want to create independent pressure
programs.
245
Using Electronic Pressure Control
Setting mass flow rate for inlets
Setting mass flow rate for inlets
When a pressure is set, the mass flow rate is displayed. Entering a new
mass flow value sets a new pressure automatically to produce the flow
value entered.
1. Enter the correct gas type, column diameter, and column length. For
more information on setting the correct column parameters, see the
appropriate sections earlier in this chapter.
2. Use the following steps to set the inlet B mass flow rate to 10 ml/min:
a.
b. Continue to press:
display.
ACTUAL
|
COLUMN
B
.000
setpoint
ml/min
The GC display looks like this.
Note: Inlet B pressure will change to the value needed to produce a
mass flow of 10 ml/min.
Setting inlet flow programs
You can use.EPC to set flow programs indirectly by setting an inlet
pressure program. The following example shows how to obtain the
pressure values necessary to set a pressure program that results in the
desired flow programs.
1. Enter the correct gas type, column diameter, and column length. For
more information on setting the correct column parameters, see the
appropriate sections earlier in this chapter.
1.
246
Using Electronic Pressure Control
Setting inlet flow programs
2. Continue to press:
ACTUAL
COLUMN
I
B
.XXX
ACTUAL
COLUMN B
I
4.0
ACTUAL
I
EPP B
10.0
setpoint
ml/min
The GC display looks like this.
SETPOINT
ml/min
SETPOINT
10.0
The GC display looks like this.
The GC display looks like this.
This will be injector B pressure initial
value.
see the mass flow control display.
ACTUAL
I
COLUMN B
4.0
ACTUAL
I
COLUMN B
7.0
ACTUAL
EPP B
14.3
SETPOINT
ml/min
The GC display looks like this.
SETPOINT
ml/min
SETPOINT
14.3
The GC display looks like this.
The GC display looks like this.The
value shown will be the inlet
pressure setting needed to obtain
the flow you entered.
Use the pressure values obtained from this procedure for setting a
pressure program. Enter the initial time, ramp rate, and final time as part
of setting the pressure program (see Setting pressure programs earlier in
this chapter). You will also need to change the oven temperature if it will
change during the pressure program.
Using Electronic Pressure Control
Setting the average linear velocity
Setting the average linear velocity
You can use EPC to set the calculated average linear velocity for inlets. For
example, when you set a pressure, the average linear velocity is displayed
(while monitoring the average linear velocity). The following sections will
show you how to:
. Understand average linear velocity
●
Calculate the outlet flow
. Set the average linear velocity
. Calculate the outlet linear velocity
. Calculate the actual average linear velocity
Understanding average linear velocity
The average linear velocity is calculated and measured at oven
temperature, rather than at ambient temperature. It is an average value
because velocity varies continually along the length of the column (due to
the pressure drop and the compressibility of the carrier gas).
To compare experimental values with those displayed by the system,
measure the outlet flow and compare it to the calculated outlet flow. Then
measure the average linear velocity and compare it to the velocity
displayed. You need to consider the corrections for both temperature and
compressibility if you use the average linear velocity (unretained peak
time) measurements to calculate flow. You can calculate an approximate
value for flow without correcting for compressibility, but it may differ
significantly from the flow value displayed by the system as the pressure
drop increases. A more detailed discussion of these calculations and
pressure versus flow relationships is given in Appendix A, Pressure versus
flow relationships for inlet and auxiliary electronic pressure control.
248
Using Electronic Pressure Control
Setting the average linear velocity
Calculating outlet flow
Outlet flow is the gas flow out of the column. It is measured in ml/min and
corresponds to the measurements made with a flow meter at the detector
outlet. The gas is measured at ambient conditions; however, the outlet flow
displayed is calculated using 25 °C and 1 atmosphere pressure (14.7 psi) as
reference conditions.
All flow calculations are based on the ideal gas law.
PV = nRT
where T = temperature in K
P = absolute pressure
Ideal Gas Law
Setting the average linear velocity
Use the following steps to set the approximate column B average linear
velocity to 100 cm/sec.
1. Enter the correct gas type, column diameter, and column length. For
more information on setting the correct column parameters, see the
appropriate sections earlier in this chapter.
2. Use the following steps to set the column B average linear velocity to
100 cm/see:
b. Continue to press:
display
ACTUAL
I
COLUMN B
SETPOINT
97.5 C m / S e c
The GC display looks like this.
The value displayed (97.5 cm/sec) is the computed average linear
Using Electronic Pressure Control
Determining the corrected column length
Note: Inlet B pressure will change to a value needed to produce
100 cm/sec at the current oven temperature. Inlet B flow also
corresponds to that pressure.
Determining the corrected column length
Packed column considerations
. Calculations for the pressure versus flow relationship with EPC apply
to flow through open tubular columns.
Measure flow versus pressure to determine the relationship for a
packed column and to check for changes as a column is used.
. Operating pressure may reach the 100 psi limit for longer columns or
higher temperatures.
. EPC offers many advantages over mass flow controllers, including:
– Precision and reproducibility of setpoints
– Rapid adjustment to change in settings during downstream
operation
– Pressure programming capability for reduced run times
To set or display the mass column flow for a packed column, you must first
calculate the corrected column length and diameter for an equivalent open
tubular column.
Capillary column considerations
Although column specifications show the nominal length of the column,
not all columns are manufactured exactly to the nominal specifications.
Also, previously used columns are shorter than” their specifications if the
ends were cut off to remove contaminants.
250
Using Electronic Pressure Control
Determining the corrected column length
To compensate for both packed and capillary column considerations, use
the following procedure to determine the corrected column length and
diameter.
Note: Before setting the mass flow rate, enter the correct gas type, column
diameter, and column length. For more information on setting the correct
column parameters, see the appropriate sections earlier in this chapter.
1. Use the following steps to set the column B average linear velocity:
I
COLUMN b
ACTUAL
SETPOINT
97.5
Cm/Sec
The value displayed (97.5 cm/see) is the computed average linear
2. Inject an unretained component into the GC and determine its
retention time in minutes. This is t 0 Actual in the following equation.
3. Use the following formula to calculate the corrected column length:
L corrected
= corrected
column length in meters
251
Using Electronic Pressure Control
Optimizing splitless injection using electronic pressure control
6. Enter the value calculated from the above formula as the corrected
column length.
You can check the flow through the column by turning off the detector
gases and measuring the flow using a bubble flow meter and the GC
stopwatch feature. See Chapter 4, Using the internal stopwatch for
more details.
Optimizing splitless injection using electronic pressure
control
The inlet carrier gas pressure at the time of injection can affect the
transfer of sample to the column dramatically. With low inlet carrier gas
pressure, the column flow rate is slower so the sample stays in the inlet
longer. Because of this, the sample has more time to expand. In addition,
low inlet carrier gas pressure results in lower inlet pressure and a larger
sample expansion volume. Conversely, higher flows (or higher pressures)
at the time of injection cause the sample to be swept into the column more
rapidly, thus reducing the expansion volume.
Because the inlet pressure can be programmed up or down, it is possible to
initiate a run with a high flow rate and then program the flow downward
to a value that is optimal for the chromatographic separation.
splitless injection volumes are usually limited to 1 to 2 µl of sample, but
this is highly dependent upon factors such as the inlet temperature,
column flow rate, solvent molecular weight, solvent boiling point, liner
volume, column type, and retention gap use. With larger injections, poor
sample transfer can result in sample losses and molecular weight
discrimination.
A slightly modified pressure programming technique is appropriate for
GC-MS systems. The program starts at a low initial pressure, then ramps
up at the beginning of the GC run, and ramps down again after the sample
has been transferred to the column.
Using Electronic Pressure Control
Optimizing splitless injection using electronic pressure control
An example of rapid pressure programming for a GC-MS system is shown
below.
Rapid Pressure Program
Init Pres
Init Time
Rate
99
Rate A
Final Pres A
Final Time
40
0.25
99
10
0
GC-MS
Final
Pres
Constant Pressure
10
0
Rate
Init
Pres
Init
Time
Final
Value
Single-Ramp Oven
Temperature Program
Rate
Init
Value
Init
Time
Example Setpoints of Rapid Pressure Programming
Init Value
Init Time
Rate
Final Value
Final Time
100
2
10
200
1
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
Operating the gas saver application for the
split/splitless inlet
What is the gas saver application?
The gas saver application is one use of the auxiliary EPC system. It allows
you to control the split vent flow of a split/splitless inlet by controlling
supply pressure to the inlet. By controlling the pressure, you can reduce
the total flow rate during nonproductive run times and laboratory
off-hours, which will reduce your GC operating costs. The gas saver is
particularly beneficial for users of expensive carrier gas and for capillary
inlet systems used with high split flows. When properly programmed for a
capillary inlet system, constant column head pressure and column flow
rate are maintained while the excess split flow is reduced.
What are the required settings for operation?
When you operate the gas saver, you must set the auxiliary pressure at
least 5 to 10 psi greater than the inlet head pressure to ensure that column
pressure and flow are maintained. To determine the minimum auxiliary
setting, detect the maximum pressure of the programmed run and add 5 to
10 psi. If you are not using constant flow mode, the column pressure drop
increases and the column flow decreases. If you are using constant flow
mode, the pressure will increase during temperature programming. In
general, the operating constraints for the gas saver application are as
follows:
. Operate at least 5 to 10 psi above column head pressure (some minimal
split vent flow is required).
. Operate at least 10 psi above the supply line pressure (or as maintained
by the system).
. Use the GC displays and warnings when configuring.
254
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
How is the gas saver application configured?
Auxiliary EPC Module
Supply
Gas Flow
Electronic
Pressure
Control
Valve
Split/Splitless Inlet,
Back-Pressure Regulation with EPC
Pressure
Transducer
255
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
How does the gas saver application operate?
When an EPC module is used for gas supply to the split/splitless inlet (gas
saver configuration), restriction is due mainly to the mass flow controller.
You can vary the restriction by changing the setting of the mass flow
controller.
To operate in gas saver mode, you need to enter the gas type, column
length, column diameter, column pressure, and split flow rate. You will also
need to calibrate the flow versus the pressure, set the mass flow controller
to the desired range, and determine the column head pressure. Be sure
that all the hardware is installed properly and that all gases are plumbed.
Use this procedure to determine the settings that will yield the most gas
savings for your system:
Zero the channel
1. Check your system for leaks.
2. Zero your channel if ambient conditions have changed significantly:
a. Make sure that all heated zones are cool.
b. Set the auxiliary and inlet pressures to zero.
c. Remove the septum nut to repressurize the system completely. The
example below shows the display for auxiliary EPC channel C.
Note: Setting the inlet pressure to 0.0 may not repressurize the
channel completed. You may also need to bleed off at the l/8-in
Swagelok fitting.
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
e.
where 10 is the zero offset value labeled “actual” on the GC display.
Enter the carrier gas pressure
1. Enter the carrier gas supply pressure at the keyboard. A typical
pressure is 50 to 60 psi.
For example:
a. Press:
Sets the channel C pressure to 50.0.
ACTUAL
SETPOINT
The GC display looks like this.
2. Turn the mass flow controller on the front of the flow panels until you
measure 80 to 100 ml/min (or the desired flow) with the bubble flow
meter.
Note: You must wait 1 to 2 minutes after changing pressure or mass
flow controller settings to allow the system to stabilize before
measuring flows or making an injection.
Enter the column parameters
table.
following:
●
Constant flow (on or off)
●
Gas type
● Vacuum
compensation (on or off)
. Column diameter
257
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
. Column length
●
Split flow
For more information on setting these parameters, see the appropriate
sections earlier in this chapter.
3. To verify the column flow, measure the flow out of the detector with a
bubble flow meter.
Set the system to operating conditions
Use the flow restrictor tables described in Setting pressure using auxiliary
electronic pressure control earlier in this chapter to select the makeup gas
pressure that will yield the flow you need. For example, the following steps
describe how to set the pressure to get 30 ml/min makeup gas flow.
1. Set the inlet pressure to 10 psi (if it is not set already).
2. Set the makeup gas at the keyboard to get to approximately 30 ml/min.
3. Start to heat any heated zones that are not already heated.
WARNING
Heat the detector before you continue.
4. If you did not select constant flow, verify the flows after the zones
reach their desired temperatures.
5. After the system reaches equilibrium, check and record the final
pressure at the maximum operating temperature.
Note: Record the final pressure so that you know what value to set for
the reduced gas saver pressure, and then observe the pressure at the
maximum operating temperature. If you want a higher temperature
than listed in the operating manual, realize what that pressure will be
when you reset it.
258
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
Set the system to off-hour conditions
If the final column pressure is 50 psi, set the carrier gas pressure to 65 psi.
During off-hours, you can program the carrier gas down.
1. Program the desired oven temperature.
2. Set all detector and inlet flows and pressures to the desired levels.
3. Set the carrier gas pressure to a value 15 psi higher than the column
head pressure.
Recommended flow rates for inlet systems using the gas saver
application
For a capillary split/splitless injection port, a combined flow rate out of the
split vent and the purge vent of approximately 5–10 ml/min is
recommended.
Additional benefits of the gas saver application
If desired, the makeup gas flow can also be reduced using the gas saver
mode during off-hours to increase total gas savings. Plumb the gas saver
outlet line into the detector manifold inlet fitting for makeup gas. Then set
it using the same procedure as for a carrier gas.
259
Using Electronic Pressure Control
Operating the gas saver application for the split/splitless inlet
With a capillary inlet, the gas saver can also be used as a quick, convenient
way to set split ratio. The graphs below show examples:
10
0
O
1
2
3
4
5
6
7
8
GC Run Time (in Minutes)
9
10
11
12
13
Split Injection
O
1
2
3
splitless Injection
4
5
6
7
8
9
GC Run Time (in Minutes)
10
11
12
13
Using Electronic Pressure Control
Using the external sampler interface
Using the external sampler interface
The external sampler interface kit (HP part number 19245-60990) enables
you to use EPC with a sampling device other than a standard HP inlet.
The conventional interfacing of external sampling devices is not possible
when EPC inlets are used. The external sampler kit provides the hardware
and diagrams for installing the kit onto forward-pressure controlled inlets
(programmable cool on-column and purged packed). The kit also contains
hardware for limited use of the back pressure-regulated split/splitless inlet.
This hardware allows the system to sense the pressure at a different
location inside the HP pneumatic system.
Which configuration should I use?
The external sampler interface is configured differently depending on the
type of inlet you use. You will select one of several typical configurations of
the external sampler interface depending on how you use your inlet. Use
the following tables to determine the configuration you need. The
diagrams shown in this section include the most commonly configured
systems.
Inlet Use
External Inlet
HP inlet used as a thermal zone
HP inlet used for injection
Inlet Use
External Sampler Interface Kit
●
●
Auxiliary Module
●
●
●
Forward-Pressure Regulation
Back-Pressure Regulation
Front End Sampler for Purged
Packed and On-Column Inlets
Front End Sampler Interface
for split/splitless Inlets
External Interface
●
●
HP inlet used for sample
introduction
●
●
HP inlet not used for
sample introduction
●
●
Using Electronic Pressure Control
Using the external sampler interface
Using Electronic Pressure Control
Using the external sampler interface
Pressure Transducer
Flow
Electronic
Pressure
Control Valve
New Pressure Sensor
Line to the Transducer
Column
Forward-pressure regulation for the septum-purged packed inlet EPC used with open tubular
columns). External sampler interface (needle through septum) to HP inlet with
forward-pressure control. A static headspace sampler can be interfaced in this way.
Configuration 1: External Sampler Interface to HP Inlet with FPR
Using Electronic Pressure Control
Using the external sampler interface
Configuration 2: External Sampler Interface to Column or to HP Inlet with FPR
The position of the three-way valve directs the EPC flow to the external
sampler or to the HP inlet. This diagram shows the EPC flow directed to
the external device.
264
Using Electronic Pressure Control
Using the external sampler interface
Pressure Transducer
Carrier
Electronic
Pressure
Control Valve
I II
Capped
Septa Purge
Forward-pressure regulation for the on-column inlet and the septum-purged packed
inlet EPC used with open tubular columns). From HP EPC pneumatics to external
sampler and return to HP inlet. This configuration should not be used with compounds
that have a retention index greater than 400-450.
Configuration 3: EPC to External Sampler to HP Inlet with FPR
265
Using Electronic Pressure Control
Using the external sampler interface
Forward-pressure regulation for the on-column inlet and the
septum-purged packed inlet EPC used with open-tubular
columns). To external sampler only. The HP pneumatics are
used. The HP inlet is not functional.
Configuration 4: EPC to External Sampler
266
Using Electronic Pressure Control
Using the external sampler interface
Back-pressure regulation for the split/splitless inlet. The external sampler is
placed in the HP split/splitless capillary inlet flow system (in series). The external
sampler transfer line was interfaced (cutting l/16-in. od tubing is required) close
to inlet carrier in line. Septa purge is capped to prevent sample losses. The
pressure sensing takes place just before the EPC valve.
Configuration 5: Back Pressure Regulated EPC with Inlet
267
Using Electronic Pressure Control
Using the external sampler interface
Carrier
Back-pressure regulation for the split/splitless inlet. External sampler
using the HP inlet back-pressure regulation of column. HP inlet not
used, The external sampler has its own direct column interface in the
unused inlet opening.
Configuration 6: Back Pressure Regulated EPC with No Inlet
268
Using Electronic Pressure Control
Using the external sampler interface
Septum Purge
Vent
Carrier
Gas
Flow
Electronic
Pressure
Control Valve
Flow
Restrictor
Capped
Septa Purge
(if required)
New Pressure Sensor
Line to the Transducer
Forward-pressure regulation for the septum-purged packed inlet EPC used with
open tubular columns). External sampler interface direct to column with HP inlet
forward EPC HP inlet used only as healed transfer and support
. . of direct column
interface device.
Configuration 7: Forward Pressure Regulated EPC with Inlet as Thermal Zone
Using Electronic Pressure Control
Using the external sampler interface
Aux EPC Module
(as Carrier Source)
Sampling Device
HP 5890 GC
Configuration 8: EPC with Auxiliary EPC Module
_
For more information on using auxiliary EPC see the headspace
configuration in Using valve options later in this chapter. For further
information, see Applications of Auxiliary Electronic Pressure Control in
Gas Chromatography, HP application note 228-202, HP publication
number (43) 5091 -5013E.
Using the external sampler interface with an inlet as a heated zone
The external sampler device introduces a slight pressure drop over the
system. To compensate for this pressure drop, measure the actual flow
with a bubble flow meter to determine the additional pressure necessary
during the run. For example, measure the flow at the column outlet, or use
an unretained peak to determine the average linear velocity. The pressure
setting will probably be somewhat higher than would be used by the
column alone.
Special considerations
If you are using an HP 19395A Headspace Sampler with a needle interface
to the inlet, replace the septum nut with the black septum nut with the
wide aperture before using it.
For easier access to the external sampler interface, try to place the
three-way flow diverter valve so it is reached easily through the side door
of the GC.
270
Using Electronic Pressure Control
Using the external sampler interface
Some devices go into a timed desorbtion cycle that increases the pressure
drop through the system, consequently reducing the flow rates. To
compensate for the increased pressure drop, program a pressure ramp at
the beginning of the start cycle. For example, ramp the pressure from 16
psi to 35 psi at 99 psi/rein. Then program the pressure down to 16 psi for
the duration of the analysis.
Whenever an external device is placed in series with an EPC inlet system,
some of the direct flow displays will be incorrect because we do not know
what the total pressure drops are relative to just the column (such as
column id and length). In this case, ignore the display and measure the
actual flows. If the external device switched valves, multiple columns, or
traps during a run, then the flows may also change. You may want to
compensate for these situations in your pressure programs.
The standard forward-pressure configuration is shown below.
Carrier Gas Flow
Forward-Pressure Regulation for the On-Column Inlet and the
Septum-Purged Packed Inlet EPC Used with Open-Tubular Columns)
Using Electronic Pressure Control
Using the external sampler interface
The standard back-pressure configuration is shown below.
Pressure Transducer
L
-
J
I
split/splitless Inlet
Carrier Gas Flow
EPC
Board
272
Using Electronic Pressure Control
Using valve options
Using valve options
The valve options described in this section demonstrate several
applications of the auxiliary EPC system. Hewlett-Packard supplies 17
standard plumbing configurations for the HP 5890. These configurations
may be ordered through the HP 18900F Valve Ordering Guide, HP part
number 5091 -4240E.
This section describes advanced auxiliary EPC valving applications that
will require some method development time from the user. In general, all
HP valves are compatible with auxiliary EPC However, some valve options
may require additional method development time. For some
configurations, such as a packed-column refinery gas analyzer that
operates isothermally, an auxiliary EPC module can be used in constant
pressure mode as easily as the standard mechanical pneumatics. With
packed-column valve applications, be sure to check the flows with a bubble
flow meter every time you change the system pressure.
If you run your system only in constant flow or constant pressure mode,
without pressure programs, then an auxiliary EPC module may be just as
effective as a manual flow controller for your applications. However, most
operations become easier to automate once you are using EPC In fact,
EPC should give faster response to changes in the back pressure of the
column and better repeatability of known retention times. When constant
flow mode is used with packed columns, actual flow may increase or
decrease with temperature programming. It is best to calibrate the flow at
the initial and final oven temperatures, and then use a two-point
calibration with pressure programming.
The following diagram shows a common 10-port valve configuration
plumbed with an EPC split/splitless inlet and one general-purpose
auxiliary EPC module. This configuration is used for the analysis of
oxygenates in gasoline.
273
Using Electronic Pressure Control
Using valve options
56-cm Micropacked TCEP
,
I
I
I
Channel C
10-Port Valve Configuration with Two Channels of EPC
274
Using Electronic Pressure Control
Using valve options
Vent
Sample
Headspace Sampling Systems Product
EPC can be applied to headspace sampling. The six-port valve
configuration in the figure above shows the application of two
general-purpose auxiliary EPC modules. One module is used for carrier gas
flow, and the other module is used for precise vial pressurization.
Using Electronic Pressure Control
Using valve options
Which valves work best with auxiliary electronic pressure control?
Almost all HP valves are compatible with auxiliary EPC and many of the
standard configurations offer additional system benefits. For example,
using valve options for specific applications can help you maintain better
reproducibility, reduce ambient temperature sensitivity, and rapidly
change the flow rate. Using valves with auxiliary EPC also contributes to
easier setup and simplified automation. In addition, auxiliary EPC valves
make it easier to change run times and to reduce analysis time.
Valve configurations such as Options 205 and 401 can also be used with
EPC If pressure programming is used, you may need to change the
pressure program whenever you change the valve timing. Failing to change
the pressure program will produce incorrect results.
A common application has Option 401 interfaced to a capillary Split inlet.
The system uses an EPC split/splitless inlet (main carrier) and one
general-purpose auxiliary EPC module for control of the second carrier
source. The interface between the capillary inlet and the valve is Option
901.
Using Electronic Pressure Control
Using valve options
Option 401.
Detector 1—FID,
Detector 2—TCD
Split Vent
I
split/splitless EPC Injection Port B
Appendix A
Pressure versus flow relationships for inlet and auxiliary
electronic pressure control
While pressure is the parameter controlled and measured with the EPC
system, the corresponding column outlet flow rate and average linear
velocity are also calculated and displayed on the keypad. Entries can also
be made in terms of either flow or velocity, from which the system
calculates the required pressure and enters this setpoint
It is important to understand how pressure, flow, and linear velocity are
related so that the displayed values can be compared with each other and
with the correct experimental measurements. This section includes a
summary of some of the basic equations for flow through open tubular
columns and the calculations that are carried out by the HP 5890 Series II
GC and HP 3365 ChemStation systems. Some of the terms and units used
throughout this section are shown below.
Terms and Units Used in This Section
280
F
Column outlet flow, ml/min
r
Column inner radius, cm
Pi
Inlet pressure, absolute
P0
Outlet pressure, absolute; zero if vacuum compensation specified
T ref
Reference temperature; 25°C = 298 K
P ref
Reference pressure; 1 atm = 14.7 psi = 1.01325x I0 6dynes/cm 2
T ref / T
2981323 = 0.923
Column
25 m x 0.32 mm, Helium carrier
Appendix A
Pressure versus flow relationships for inlet and auxiliary electronic pressure control
Outlet flow
Column outlet flow can be calculated from Equation 1:
Since the gas volume depends on both temperature and pressure, it is
expressed here under reference conditions, Tref and Pref. Flows displayed
by the 5890 are based on reference conditions of 25 °C and 1 atmosphere
pressure, for comparison with experimental values measured under
ambient conditions with a flow meter at the outlet of the detector.
Average linear velocity
Flow cannot always be measured directly at the detector outlet, as in work
with a mass spectrometer or at very low flow rates. An alternative is to
measure the elution time for an unretained peak and calculate the average
linear velocity for gas flowing through the column. This value is
determined at oven temperature T.
Eq 2
The average linear velocity can also be calculated from pressure,
temperature, and column parameters according to Equation 3, as was done
for outlet flow using Equation 1. (Temperature does not appear separately,
but is included in the viscosity term in this equation.)
This is the calculation used for the velocity value displayed by the HP
5890. It is calculated at oven temperature, corresponding with
experimental measurements from elution time of an unretained peak
(equation 2).
Appendix A
Pressure versus flow relationships for inlet and auxiliary electronic pressure control
Calculating flow from average linear velocity
Combining equations 1 and 3 gives an equation that can be used to
calculate flow from average linear velocity.
Terms for both temperature and pressure appear in this equation. The
ratio Tref/T corrects for the difference in temperature (ambient versus
oven) at which flow and velocity were calculated. The pressure term is
related to effects of the gradient from inlet to outlet pressure. Because the
carrier gas is compressible, linear velocity varies along the length of the
column, depending on the pressure at each point. Retention time
pressure-gradient term must be included to calculate flow at the outlet.
Column flow is often approximated from measurements of unretained
peak time according to equation 5, without including these corrections (see
Chapter 4, Setting Inlet System Flow Rates earlier in this manual).
This can be a good approximation, when the pressure drop is small and
temperature is near Tref. The compressibility correction becomes
increasingly important as the pressure drop increases, however, and flow
values approximated using equation 5 may differ significantly from those
calculated by the system according to equation 4.
The examples below show how the two flow calculations compare for one
column under different sets of operating conditions. In these examples,
temperature has been held constant to illustrate the effect of changes in
the compressibility factor. It can be seen from the equations, however, that
changes in the temperature ratio will also affect the overall result and
comparison between calculations.
Appendix A
Pressure versus flow relationships for inlet and auxiliary electronic pressure control
Keyboard Displays
Example
Inlet Pressure
Flow (ml/min)
Velocity (cm/see)
1
4.6 psig (19.3 psia)
1.00
19.3
2
8.3 psig (23.0 psia)
2.00
34.5
3
14.3 psig (29.0 psia)
4.00
58.4
Example I—Inlet pressure 4.6 psig
1. Calculating flow from the average linear velocity using equation 4:
F = (0.0482) (0.923) [1.164] (19.3) = 1.00
2. Calculating flow from the average linear velocity using the
approximation in Equation 5:
Example 2-Inlet pressure 8.3 psig
1. Calculating flow from the average linear velocity using Equation 4:
F = (0.0482) (0.923) [13.03] (34.5) = 2.00
2. Calculating flow from the average linear velocity using the
approximation in Equation 5:
283
Appendix A
Pressure versus flow relationships for inlet and auxiliary electronic pressure control
Example 3—Inlet pressure 14.3 psig
1.
F = (0.0482) (0.923) [1.540] (58.4) = 4.00
2,
Calculating flow from the average linear velocity using the
approximation in equation 5:
References
More detailed discussions on pressure versus flow relationships in capillary
GC can be found in many general references; two are listed here.
1. WE. Harris and H.W. Habgood, Programmed Temperature Gas
Chromatography, Wiley, New York, 1966.
2. J.C. Giddings, Unified Separation Science, Wiley New York, 1991.
284
Index
A
Adapters, bubble flow meter, 72
Assigning a signal, 171
Attenuation
on/off, output signals, 179
output signals, 176
Auxiliary zones
suggested pressure ranges, 234
temperature control, 66
with EPC 217
installation in packed inlets, 27
installation in split/splitless inlets, 30
installation in TCD, 38
preparation, 17
Capillary inlet
flows, 77
flows in split mode, 79
flows in splitless mode, 85
Carrier gas, for TCD, 127
Carrier gases, type, 92
Average linear velocity 248,249,281
Column
corrected length, 250
diameter, 243,257
length, 243,257
Bead
conditioning, 136
contamination, 145
power setting, 138
preserving lifetime, 146
Column compensation
assigning data, 133, 194
displaying status, 130
making a compensation run, 131
message displays, 132
single, 129
starting a run, 192
status display, 191
Bubble flow meter, 70
adapters, 72
c
Capillary columns
corrected length, 250
flows for FID, 114
flows for NPD, 141
flows for TCD, 124
flows with ECD, 154
flows with FPD, 162
installation in ECD, 42
installation in FID, 35
installation in FPD, 46
installation in NPD, 35
Column installation, 16
1/4 in. metal in FID, 32
1/4 in. metal in NPD, 32
1/8 in. in FID, 33
1/8 in. in NPD 33
1/8 in. metal in FPD 44
1/8 in. metal in TCD, 37
capillary in capillary inlets, 30
capillary in ECD, 42
capillary in FID, 35
capillary in FPD 46
capillary in NPD 35
capillary in packed inlets, 27
capillary in TCD, 38
285
Index
capillary inserts, 19
glass columns in ECD, 40
glass columns in packed inlet, 25
metal columns, 23
radioactive leaks, 159
selecting gases, 152
temperature effects, 150
US owners, 148
Column preparation
capillary columns, 17
metal columns, 20
Electronic pressure control
FID, 118
FID makeup gas, 120
Compensation, single column, 129, 190
EPC 216
and valves, 276
auxiliary pressure control, 230
auxiliary zones, 217
auxiliary, suggested ranges, 234
constant flow mode, 225
detectors, 217
flow and pressure relationships, 280
inlets, 217
mass flow rate, 246
optimizing splitless injection, 252
programming inlet flow, 246
safety shutdown, 220
vacuum compensation mode, 244
Constant flow, inlets, 245
Cryogenic oven control, 55
D
Daily shutdown, 11
Daily startup, 11
Detectors
ECD, 148
FPD 160
nitrogen–phosphorus, 134
pressure control, 231
pressure programming, 232
status, 97
temperature control, 65, 66
temperature display, 65
with EPC 217
Display, output signals, 173
E
ECD
contamination, 157
flow rates, 151
flows for packed columns, 153
flows with capillary columns, 154
gases, 150
installing capillary columns, 42
installing glass columns, 40
leak testing, 159
operation, 148
pressure control, 156
EQUIB’ TIME, 53
Equilibration time, 54
External sampler interface, 261,270
F
FID
flows for capillary columns, 114
gas flows, 113
installing capillary columns, 35
installing metal columns, 32, 33
lighting flame, 121
makeup gas control, 119
on/off control, 121
operation, 110
optimizing, 110
FINAL TIME, 58
FINAL VALUE, 58
Index
Flow control
EPC 239
inlet programming, 246
Flow ranges, packed inlet, 73
Flow rates
bubble meter, 70
display, 92
measuring, 70
outlet, 249, 281
recommended for gas saver, 259
Flows
capillary columns with FID, 114
capillary columns with FPD 162
capillary inlet, 77
capillary spIit mode, 79
capillary splitless mode, 85
displays, 241
ECD, 151
ECD with packed columns. 153
EPC constant flow mode, 225
FID, 113
NPD with capillary columns, 141
NPD with packed columns, 140
packed columns with FPD 161
stopwatch, 93
FPD
flows for packed columns, 161
flows with capillary columns, 162
installing capillary columns, 46
installing metal columns, 44
lighting the flame, 167
on/off control, 166
operation, 160
pressure control, 164
G
Gas flows, FID, 113
Gas saver
operation, 254
recommended flows, 259
zeroing, 256
Gas selection, ECD, 152
Gas type, 242
Gases, ECD, 150
Glass columns
installation in ECD, 40
installation in packed inlets, 25
H
Heated zones
actual, 51
detector temperatures, 65
inlet temperatures, 65
setpoints, 51
I
INET, 181, 195
start/stop a run, 185
INIT TIME, 58
INIT VALUE. 58
Inlet flow control, 70
Inlets
constant flow, 245
flow rates for gas saver, 259
gas saver and capillary inlet, 254
mass flow rate, 246
pressure control with EPC 222
pressure programming, 226
programming flow, 246
temperature control, 65,66
temperature display, 65
with EPC 217
Inserts, split/splitless inlet, 19
Installation, checklist, 10
Installing columns, 16
Index
o
L
Leak test, ECD, 159
Leak testing, ECD, radioactive, 159
LED, status indicators, 185
Lightening the flame, FPD 167
Loading setpoints, 206,207
lows, capillary columns with ECD, 154
On/off control
FID, 121
FPD 166
NPD 145
signal attenuation, 179
signals, 176
TCD, 128
valves, 198, 213
Optimizing
NPD 145
splitless injection, 252
Makeup gas, FID, 119
Outlet flow, 249
Making a run, 184
Outlet flow rate, 281
Mass flow rate, 246
Output signals
and INET, 181
as timed events, 200
assigning, 171
attenuation, 176
attenuation on/off, 179
display or monitor, 173
on/off control, 176
zeroing, 175
Metal columns
installation in FID, 32, 33
installation in FPD 44
installation in NPD 32, 33
installation in packed inlets, 23
preparation, 20
NPD
bead lifetime, 146
bead power, 138
conditioning the bead, 136
contamination, 145
flows for capillary columns, 141
flows for packed columns, 140
installing capillary columns, 35
installing metal columns, 32, 33
on/off control, 145
operation, 134
optimizing, 145
288
Oven
cryogenic operation, 55
temperature control, 53
temperature control and display, 53
temperature programming, 58
OVEN MAX, 53
OVEN TEMP 53
Index
P
Packed columns
corrected length, 250
ECD flows, 153
flows for NPD, 140
flows for TCD, 123
flows with FPD, 161
gas flows for FID, 113
Packed inlet
flow ranges, 73
installing capillary inlets, 27
installing glass columns, 25
installing metal columns, 23
septum purge, 74
Polarity inversion, TCD, 128, 180
Pressure control
auxiliary EPC, 230
capillary columns with FPD, 164
detector programming, 232
detectors, 231
ECD, 156
EPC, zeroing, 222
for FID, 117
for FID makeup gas, 120
for TCD, 125
inlet programming, 226
inlets with EPC, 222
NPD with capillary columns, 143
restrictors, 234
Programming
checking inlet pressures, 229
detector pressure, 232
inlet flow, 246
inlet pressure, 226
oven temperature, 58
R
RATE,58
Restrictors, 234
Run
making, 184
start/stop, 184
start/stop using INET, 185
s
Safety shut down, 220
Sensitivity, TCD, 128,201
septum purge, 74
SETPOINTS
loading, 206,207
storing, 206
Shutdown, instrument, 11
signal output,
170
Signals
and INET, 181
as timed events, 200
assigning, 171
attenuation, 176
attenuation on/off, 179
display or monitor, 173
on/off control, 176
zeroing, 175
Single column compensation, 129,190
Split mode, flows in capillary inlet, 79
Index.
Split/splitless inlet
gas saver, 264
inserts, 19
installing capillary columns, 30
Temperature limits, 52
Splitless injection, optimizing, 252
Time key 188
Splitless mode, flows in capillary inlet, 85
Timetable
creating an event, 198
events, 196
modifying events, 202
switching signals, 200
valve control, 214
Start/stop control, run, 184
Startup, instrument, 11
Status
column compensation, 191
LEDs, 185
valves, 212
Stopwatch, 93,189
Storing setpoints, 206
T
TCD
carrier gas type, 127
changing sensitivity, 201
flows for capillary columns, 124
flows for packed columns, 123
installing capillary columns, 38
installing metal columns, 37
on/off control, 128
operation, 122
polarity inversion, 128, 180
pressure control of flow, 125
setting sensitivity, 128
Temperature, effects on ECD, 150
Temperature control
auxiliary zones, 66
detectors, 66
heated zones, 50
oven, 53
Temperature programming, oven, 58
v
Vacuum compensation, 244
Valve, status, 212
Valve box, 67
Valves
and “EPC, 276
controlling, 212
during a run, 198
on/off control, 198, 213
options, 273
w
WARN:OVEN SHUT OFF, 55
Wipe test, ECD, 159
z
Zeroing
EPC pressure, 222
gas saver, 256
output signals, 175

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