Illustrated Glossary of Organic Chemistry

Gas chromatography-mass spectrometry (GC-MS): A technique to determine the quantity and identity of components in an analyte. The analyte is injected into a gas chromatograph (which separates the mixture into its individual components), and the output from the gas chromatograph fed into a mass spectrometer (which determines the molecular formula of each component). The mass spectra of each component can often be compared against a computer library of mass spectra of known compounds. GC-MS is frequently used in forensic applications such as drug (or drug metabolite) identification and tissue analysis. Note: The abbreviation GC-MS can refer to the technique (gas chromatography-mass spectrometry) or to the instrument (gas chromatograph-mass spectrometer).

Schematic representation of a GC-MS instrument.

A modern GC-MS instrument.