Headspace sampler is a tool for introducing volatiles that are

contained in liquid or solid samples into a gas chromatograph. The analytical

technique is called “static headspace gas chromatography.” The term

“headspace” refers to the space above the liquid or solid sample that you place

in a sealed vial. The term “static” means that the volatiles in the headspace of

the vial are at equilibrium with the same compounds in the liquid or solid

sample.

The instrument extracts a reproducible volume of the headspace and injects it

into the carrier gas flowing into the gas chromatograph. Food, packaging,

pharmaceutical products, soil, and water are often tested to see if they meet

quality criteria or regulatory standards. Fragrances and consumer products are

analyzed using headspace in order to understand their composition. Forensics

laboratories use headspace for measuring the percent of ethanol in human

blood to see if a driver is legally intoxicated.

The ease with which a sample forms a gaseous headspace depends on the

sample’s “partition coefficient.” See “Developing Methods” on page 68 for a

more thorough explanation. After a programmed heating time, the headspace

gas is extracted from the vial and injected into a GC for analysis.

There are two means of extracting the headspace gas from the vial—single or

multiple headspace extraction (MHE). With single headspace extraction, only

one sample of gas is taken from each sample vial. Single headspace extraction

is the standard method. It is used for samples that are readily volatile or for