Knowra Gas chromatography–mass spectrometry Gas chromatography–mass spectrometry Gas chromatography–mass spectrometry (GC–MS) couples gas chromatography, which separates volatile compounds, with mass spectrometry, which measures their ions to support identification and quantification.
Gas chromatography : An analytical technique that separates vaporized compounds as they travel through a column in a carrier gas. Its column separates mixture components before they enter the mass spectrometer.
Volatility : A substance's tendency to enter the gas phase, influenced by its vapor pressure and intermolecular forces. GC generally requires analytes that can be vaporized without unacceptable decomposition.
Forensic toxicology : The application of toxicology to legal investigations, including detection and interpretation of drugs and poisons. GC–MS can identify and measure many drugs and toxic compounds in biological specimens.
Liquid chromatography–mass spectrometry : An analytical method that separates compounds in a liquid mobile phase before mass-spectrometric detection. LC–MS handles many nonvolatile or thermally fragile analytes that GC–MS cannot readily analyze.
Mass spectral library : A searchable collection of reference mass spectra associated with chemical compounds. Library matching can suggest identities, but results depend on coverage and spectral similarity.
Electron ionization : A mass-spectrometric ionization method that bombards gas-phase molecules with energetic electrons, producing molecular and fragment ions. It commonly generates reproducible fragmentation patterns for GC–MS library matching.
Partition coefficient : A ratio describing how a substance distributes between two phases at equilibrium. Different partitioning between the carrier gas and stationary phase creates chromatographic separation.
Environmental monitoring : The systematic measurement of chemical, physical, or biological conditions in the environment. GC–MS is used to detect trace organic pollutants in air, water, soil, and biota.
Gas chromatography–flame ionization detection : A gas chromatographic method that detects compounds through ions formed in a hydrogen–air flame. GC–FID often quantifies organic compounds robustly but does not provide mass spectra for identification.
Retention index : A normalized measure of chromatographic retention, commonly calculated relative to reference compounds such as n-alkanes. Retention indices provide evidence that can support or challenge a spectrum-based identification.
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