Gas chromatography
Description
An analytical technique for the qualitative and quantitative analysis of materials. Gas chromatographs (GCs) are generally used to detect individual components (volatile at 500C or below) in a mixture. The sample, a gas or volatilized liquid, is injected through a port into a flowing stream of inert carrier gas such as Helium, Argon, Nitrogen or Hydrogen The sample and carrier gas pass through a column which contains a stationary phase that separates the individual sample components viah a gas-liquid adsorption/desorption partitioning process. The separated components are flushed sequentially from the column to a detector. Available detectors are flame ionization (FID), thermal conductivity (TCD), electron capture (ECD) and mass spectrometry (MS). The elapsed time from injection to detection is defined by the retention time for an individual species. Identification and quantification of the sample's components are achieved by comparison of their retention times and peak areas to those of reference standards analyzed under the same conditions. Gas chromatographs with mass spectrometer detectors can provide positive identification of compounds at the low parts per billion level. Compounds with boiling points higher 550 C can be analyzed after chemical modifications, such as silylation. Alternatively, Pyrolysis Gas Chromatogrpahy (Py-GC) has a specially heated sample inlet that can thermally dissociate the sample components the into volatile fragments. This is useful for the identification of polymers.
Synonyms and Related Terms
GC; Gaschromatographie (Deut.); chromatographie en phase gazeuse (Fr.); Pyrolysis Gas Chromatography (Py-GC); vapor-phase chromatography (VPC); gas-liquid partition chromatography (GLPC)
Resources and Citations
- Wikipedia: Gas Chromatograph Accessed June 2023
- National Gallery of Art, Scientific Research: Glossary of Conservation Terminology
- http://www.c2rmf.fr/homes/home_id21988_u1l2.htm
- Walter Hopwood, Submitted information