GC-MS GC-MS is an acronym for the combined gas chromatography and mass spectrometer instrument. There is a wide range of these combinations with an equivalent wide range of unique interfaces for coupling the two. The chromatograph can be a gas chromatograph with a packed or capillary column, or a super critical liquid chromatograph with a wide rage of different types of column. The mass spectrometer may be an ion trap mass spectrometer, a quadra-pole, or octa-pole mass spectrometer, it may be a sector mass spectrometer or a time-of-flight-mass spectrometer. The mass spectrometer may be fitted with one of a number of different ionizing sources, the electron impact source, the chemical ionization source, the atmospheric pressure ionization source, or the inductively coupled plasma ionization source. The interfaces are also numerous, the Bieman concentrator and the Ryhage concentrator each concentrates the solute in the eluting gas before entering the mass spectrometer. Due to the high sensitivity of the mass spectrometer the overall system is also very sensitive and sub microgram quantities of material are usually more than adequate for analysis. The combination of a separating technique such as gas chromatography with an identifying technique such as mass spectrometry is an extremely powerful combination and is used widely in all types of analyses but, particularly in forensic chemistry, pollution chemistry, pharmaceutical chemistry and toxicology.