Thermal Desorption / Gas Chromatography / Mass Spectrometry combines the advantages of utilizing three techniques for solving difficult problems in organic analysis. Head Space Analysis (HSA), also known as Thermal Desorption, was initially developed for analysis of volatile compounds in matrices that could not be directly injected into a gas chromatograph. Dynamic Headspace is a non-equilibrium technique.

The technique works by subjecting the sample to elevated temperatures for a period of time to drive volatile compounds from the sample matrix into the atmosphere above the sample, called the “head space”. Helium continuously sweeps the chamber, carrying with it the components that have outgassed. The purge gas is passed through an adsorbent trap that contains (in order): glass beads, Tenax^TM, and charcoal and is cooled down to -100°C. At the conclusion of the experiment, the trap is thermally desorbed (in reverse flow) directly into the inlet of a gas chromatograph. The components that were present on the trap are separated by Gas Chromatography and identified using Mass Spectrometry. An external standard usually deuterated n-hexadecane is used to provide semi-quantitative results.