Let’s understand the Headspace gas Chromatography

01 Basic principles of headspace analysis

Headspace analysis is through the sample matrix at the top of the gas composition to determine the content of components in the original sample, the basic theoretical basis is under certain conditions the gas phase and the condensed phase (liquid or solid phase) balance exists between distribution, we may consider the headspace analysis is a method of gas phase extraction which USES gas as solvent to extract the volatile components in the samples. The sensitivity of headspace analysis is relatively high, which can meet the requirements of regulations. Moreover, as an analysis method, headspace analysis only takes the gas phase for analysis, which greatly reduces the interference of sample matrix to analysis.

02 Basic types of headspace gas chromatography

1. Dynamic headspace gas chromatography

The method using inert gas into liquid or solid samples, the volatile gas content of the purging out, selective enrichment (adsorbent, cold trap, etc.) are available, and then by heating (or other methods) the enrichment of the gaseous components by the carrier gas to the gas phase in the chromatographic column separation analysis, this method is also called purging – capture by gas chromatography.

2. Static headspace gas chromatography

In static headspace chromatography, the sample is sealed in a container, placed at a certain temperature for a period of time to achieve equilibrium between the gas-liquid two phases, and then the gas-phase part is taken into GC analysis. Static headspace GC is also known as a gas phase extraction, namely according to the analysis of the sample at this time to determine the content of volatile components in the original sample, if you take the second sample, the result is different from the first sampling analysis results, this is because the first sample composition has changed after sampling, this method is also our most commonly used by headspace gas chromatography.

03 Application of headspace gas chromatography

Headspace chromatography has been widely used in environmental detection (such as volatile halohydrocarbons in drinking water and volatile organic compounds in industrial wastewater), detection of organic residual solvents in drugs, food, forensic science, petrochemical industry, packaging materials, coatings and brewing industry analysis.

Headspace gc can also be used to determine solid polymers and polymer dispersion systems. This technique is much more sensitive to detecting residual monomers than the conventional method of dissolving and resettling polymers. Headspace gas chromatography is also a fast and simple method to test the chemical stability of polymers.

04 Application examples of headspace gas chromatography

1. Welch WM inowax (30M) × 0.25mm,0.25 μ m) Determination of acetaldehyde in glacial acetic acid

2. Welch WM-624 (30M × 0.53mm, 3.0 μ m) Determination of residual solvent in polyvinyl alcohol