Headspace Analysis; Headspace Techniques - Agilent Technologies 7697A Advanced Operation Manual

Headspace Analysis

Headspace techniques

Advanced Operation
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.
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.
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Introduction
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