Agilent Technologies 7697A User manual

Agilent Technologies
Agilent 7697A
Headspace Sampler
Advanced Operation

Notices
© Agilent Technologies, Inc. 2011
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laws.
Manual Part Number
G4556-90016
Edition
Second edition, November 2011
First edition, January 2011
Printed in USA
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Wilmington, DE 19808-1610 USA
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CAUTION
A CAUTION notice denotes a hazard. It
calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in damage to the product
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until the indicated conditions are fully
understood and met.
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A WARNING notice denotes a hazard.
It calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in personal injury or
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met.

Advanced User Guide 3
Contents
1 Introduction
About This Manual 8
The Keypad 9
Headspace Analysis 11
Headspace techniques 11
Static headspace sampling techniques 12
2 How the 7697A Headspace Sampler Works
How the HS Processes a Sample Vial 16
How the HS Equilibrates a Vial 18
How the HS Pressurizes a Vial 19
Fill at flow to pressure 19
Fill to pressure 19
Fill with constant volume 20
Dynamic leak check 20
How the HS Fills the Sample Loop (Extracts a Sample) 21
Default loop fill mode 21
Custom loop fill mode 21
Types of HS Extractions and Injections 22
Standard extraction 23
Multiple headspace extractions 24
Concentrated headspace extractions 24
Venting residual vial pressure 25
How the HS Reduces Carryover 26
3 Method Development
Overview 28
Consider the Sample and Matrix 29
Theory of headspace analysis 29
Impact of K and phase ratio 30
Consider the GC Inlet 33
Load a Similar Method 34
Edit the New Method 35
Temperatures 35
Times 36
Vial 37

4Advanced User Guide
Carrier 38
Purge time and flow 41
Other parameters 42
Developing and Improving the Method 43
Using parameter increment 43
Vial size 45
Vial shaking 45
Sample loop size 45
Pressurizing the vial 46
Filling the sample loop 47
Extraction mode 50
Sequence Actions 52
Types of sequence issues handled 52
Available actions 53
Sequence actions and data systems 54
Optimizing Throughput 55
Setting Up for a New Method 57
Perform blank runs 58
4 The Barcode Reader
About the Barcode Reader 60
To Use the Barcode Reader 61
Supported Barcodes 63
Supported Barcode Labels 64
5 Configuration
Configuration 66
Configuration Parameters 67
APG Remote Polarity 69
APG Remote signal electrical specifications 69
APG Remote - Suggested drive circuits 70
APG Remote connector 70
APG Remote signal descriptions 70
Configuring Carrier Gas Control 72
GC Control 72
HS Control 75
GC + HS Control 75
Instrument Schedule (Resource Conservation) 76
Resource conservation when using an Agilent data system 76

Advanced User Guide 5
To program an instrument schedule 76
6 Options
Calibration 80
To calibrate the atmospheric pressure sensor 80
To calibrate the tray 80
To calibrate the gas sensors 81
Communication 82
To set the LAN address at the keyboard 83
To use a DHCP server 83
Keyboard and Display 84
7 Early Maintenance Feedback
What is Early Maintenance Feedback? 86
To Set Up EMF for Use 87
To Set a Limit for a Counter 88
To Reset a Counter 89
To Disable EMF 90

6Advanced User Guide

7
Agilent 7697A Headspace Sampler
Advanced Operation
Agilent Technologies
1
Introduction
About This Manual 8
The Keypad 9
Headspace Analysis 11
This chapter introduces the Agilent 7697A Headspace
Sampler and some basic concepts of headspace analysis.

8Advanced Operation
1Introduction
About This Manual
This manual supplements the Operation guide. Use this
manual as a resource when developing a method. It contains
reference information, concepts, and procedures about:
•Headspace theory
•Theory of operation for the headspace sampler
•Advanced functionality
•Method development
•Configuration
•Optional settings

Introduction 1
Advanced Operation 9
The Keypad
This manual describes the functionality of the Agilent 7697A
Headspace Sampler when operating primarily in standalone
mode, using the keypad. Most information relates to the
parameters available from the instrument keypad, shown in
Figure 1 below.
Figure 1 Agilent 7697A HS keypad
If using an Agilent data system with the optional HS control
software, more functionality is available:
•Expanded use of the instrument schedule
•Method creation wizard
•Method conversion wizards

10 Advanced Operation
1Introduction
•More flexible sequencing
If using a data system, see the data system help for more
details. Connect to the HS instrument, open the method
editor, and click the help icon ( ) or press F1.

Introduction 1
Advanced Operation 11
Headspace Analysis
Headspace analysis is a technique for analyzing volatile
organic compounds using gas chromatography. Headspace
analysis samples the ambient volume above a sample matrix,
where the volatile compounds exist in gaseous form at
predictable levels.
Headspace analysis is useful for situations where:
•The analyte of interest is volatile at temperatures below
285 °C (111 vial model) or 195 °C (12 vial model).
•The sample matrix is a solid, paste, or a liquid that is not
easy to inject into a GC inlet.
•Sample preparation to allow easy liquid injection is
currently difficult.
Headspace analysis provides several advantages over
traditional injections:
•Simpler sample preparation. The sample does not need to
be processed until injectable as a liquid.
•Directly analyze a wide range of sample matrices (liquids,
solids, and pastes).
•Solvent peak is smaller or nonexistent compared to
traditional liquid injection GC techniques.
•Columns last longer, with less maintenance. The
headspace volume above the sample matrix is more clean
than the matrix. By injecting fewer contaminants, the
analytical column lasts longer and requires less
maintenance (trimming, bakeout, guard column
replacement, and so forth).
•High precision.
Headspace techniques
At this time, there are three main techniques for performing
headspace analysis.
Dynamic headspace sampling: This technique, typically part
of a purge and trap system, uses a continuous flow of
carrier gas to purge any volatile components from the
sample matrix. These analytes are usually trapped in an
adsorbant. After a specified time, the trap is heated,
releasing the adsorbed compounds, which are swept into the
GC inlet.

12 Advanced Operation
1Introduction
Static headspace sampling: This technique uses a closed
sample container and a sampling system. After placing the
sample matrix into the sealed sampling vial, the sample
matrix is heated for a specified time, during which the vial
can also be agitated (shaken) to help drive volatile
compounds from the matrix and into the headspace volume.
After a specified time, the vial is punctured, pressurized,
and an amount of the headspace vapors are withdrawn and
injected into the GC inlet.
Solid Phase Micro Extraction: In this technique, a probe
with an adsorbant is placed into a vial that contains the
sample matrix. The analytes of interest adsorb into the
sample probe. Use of different adsorbants provides flexibility
for analyzing different compounds of interest (while ignoring
others). After a specified time, the probe is heated to drive
off the analytes, which are swept onto the GC column.
Static headspace sampling techniques
There are two main static sampling headspace techniques,
pressure- transfer and valve and loop. (A third technique,
performing the injection manually using a gas- tight syringe,
does not provide easily reproducible results.)
Pressure transfer systems
The pressure- transfer system uses a specialized needle for
vial pressurization and sampling. The vial is heated and
agitated for the desired time. Then, the sampling needle
punctures the vial, and carrier gas pressurizes the vial. After
an equilibration time, the needle allows pressurized gas to
flow into the GC inlet for a specified duration. Typically, the
sample gas flows into the GC inlet due to the pressure
difference between the sample vial and the GC inlet. While
the results are repeatable, exact amount of sample gas is
unknown.

Introduction 1
Advanced Operation 13
Figure 2 Pressure transfer system
Valve and loop systems
The valve and loop system, as used in the 7697A, also heats
and agitates the vial for a specified time. However, the
Agilent system uses a sample loop of known size to collect
the sample. The sampling steps for the valve and loop
system are:
1A needle probe punctures the vial.
2The sampler pressurizes the vial with gas. See Figure 3.
3After equilibration at pressure, the pressurized vial gases
vent through the sample loop, filling the loop with
sample. Note that the vial vents to atmospheric pressure
in this case, not to a high column head pressure. Also,
the 7697A can control the flow of gas into the sample
loop so that the sampling ends before the vial completely
depressurizes.
4After the sample loop equilibrates, the valve switches and
the sample loop becomes part of the flow path into the
GC inlet. The carrier gas sweeps the known sample
amount into the GC inlet for analysis.
Carrier gas

14 Advanced Operation
1Introduction
Figure 3 Valve and loop system sampling and injection stages
1
2
34
5
6
Sample
probe
Carrier gas Vent
1
2
34
5
6
6 port valve
Transfer
line Sample loop
Sample
probe
Carrier gas Vial
pressurization gas
1
2
34
5
6
Sample
probe
Carrier gas Vent
Vial pressurization
Sample loop filling
Injection

15
Agilent 7697A Headspace Sampler
Advanced Operation
Agilent Technologies
2
How the 7697A Headspace Sampler
Works
How the HS Processes a Sample Vial 16
How the HS Equilibrates a Vial 18
How the HS Pressurizes a Vial 19
How the HS Fills the Sample Loop (Extracts a Sample) 21
Types of HS Extractions and Injections 22
How the HS Reduces Carryover 26
This chapter describes the basic theory behind the 7697A
headspace sampler.

16 Advanced Operation
2How the 7697A Headspace Sampler Works
How the HS Processes a Sample Vial
Figure 4 shows the workflow for a vial processed by the 12
vial model HS.
Figure 4 Basic 7697A HS vial process flow, 12 vial model
Figure 5 shows the workflow for a vial processed by the 111
vial model HS (with tray).
Prepare sample.
Cap sample in vial.
Place vial in
carousel
Lift vial into oven.
Equilibrate.
Lift vial onto sample
probe.
Pressurize vial.
Perform dynamic
leak test.
Remove vial from
probe.
Lower vial into
carousel.
User tasks
Perform extractions and injections:
If Single:
-Fill sample loop.
-Start run, vent vial (optional)
If Concentrated:
-Fill sample loop, inject, repeat
(pressurize, test, fill loop, inject).
-Start run, vent vial (optional)
If Multiple extractions:
-Fill sample loop.
-Start run, vent vial (optional)
-Repeat.

How the 7697A Headspace Sampler Works 2
Advanced Operation 17
Figure 5 Basic 7697A HS vial process flow, 111 vial model
The major differences in processing between the two models
are:
•Tray robotic arm moves vials to and from loading stations
•111 vial model uses a 12 vial oven that can process more
than one vial at a time
•111 vial model provides shaking
Prepare sample.
Cap sample in vial.
Place vial in tray.
Lift vial and move to
shutter.
Equilibrate (temperature
and shaking)
Lift vial onto sample
probe.
Pressurize vial.
Perform dynamic
leak test.
Remove vial from
probe.
Lower vial into
carousel.
User tasks
Open shutter, lower vial
into oven, close shutter.
Move vial to cooling
station.
Return vial to tray.
Return vial to shutter.
Perform extractions and injections:
If Single:
-Fill sample loop.
-Start run, vent vial (optional)
If Concentrated:
-Fill sample loop, inject, repeat
(pressurize, test, fill loop, inject).
-Start run, vent vial (optional)
If Multiple extractions:
-Fill sample loop.
-Start run, vent vial (optional)
-Repeat.

18 Advanced Operation
2How the 7697A Headspace Sampler Works
How the HS Equilibrates a Vial
The 7697A HS with tray has a vial oven that can equilibrate
up to 12 vials (depending on model) at temperatures from
ambient + 5 °C up to 300 °C. In addition, the oven can
shake the vials at 9 different acceleration levels. As long as
sequence vials share the same equilibration settings, the HS
determines when consecutive samples can be loaded into the
oven to increase throughput, then automatically loads them.
The HS optimizes for throughput regardless of extraction
mode, loop fill mode, and so forth.
The 12 vial model oven can equilibrate a single vial at
temperatures from 35 °C up to 210 °C. Shaking is not
available.

How the 7697A Headspace Sampler Works 2
Advanced Operation 19
How the HS Pressurizes a Vial
All 7697A HS provide several techniques for pressurizing the
sample vial. In addition to simply heating the vial, which
may generate enough internal pressure on its own, the HS
can provide additional gas to help with extraction. This gas
comes from the Vial pressure fitting on the HS back panel,
and can be different from the carrier gas used to move the
sample onto the column. While the default vial
pressurization method is often sufficient, the alternative
techniques may be useful in some applications. See Figure 6
below.
Figure 6 Pressurizing the vial
Fill at flow to pressure
This is the default vial fill mode. In this mode, the HS
maintains a specified flow rate of carrier gas into the vial
until the pressure inside the vial reaches the fill pressure
setpoint. The HS maintains this pressure for the hold time.
At the end of the hold time, the sample loop fill begins.
Fill to pressure
In this mode, the HS fills the vial as rapidly as possible to
the target fill pressure setpoint, then maintains this pressure
for the specified hold time. At the end of the hold time, the
sample loop fill begins.
1
2
34
5
6
6 port valve
Transfer
line
Sample loop
Sample probe
Carrier gas Vial
pressurization gas

20 Advanced Operation
2How the 7697A Headspace Sampler Works
Fill with constant volume
In this mode, the HS pressurizes the sample vial with a
specified volume of carrier gas, then maintains the resultant
pressure for the specified hold time. This mode is useful if
you need to calculate the exact molar amounts of sample
and carrier gas in the vial or sample loop.
Dynamic leak check
By default, the HS performs a leak check after the vial
pressurization. While on the probe, the HS can determine if
the vial is leaking. If the HS must continually add gas to
maintain the desired pressure in the vial, then the vial is
leaking. The HS logs the leak test results, and provides a
sequence action to allow you to handle (for example, skip or
abort) a leaking sample vial. See “Sequence Actions”.
The time spent on dynamic leak test is equal to Pressure
Equilibration Time + .02 minutes.