Definition of Gas Chromatography Mass Spectrometry

Gas​ Chromatography-Mass Spectrometry is an analytical method which has the characteristics of both mass spectrometry and gas chromatography. This is performed to detect the substances that are present in a sample that is to be tested. This technique is used in the identification of drugs and the investigation of fires and explosive materials. This is also used at airports to detect the luggage and is interpreted as an important and prime standard for the identification of forensic materials. The instrument of GC-MS has two units.


First, the gas chromatograph is composed of a capillary column which is responsible for the separation of the test sample. The separation is done based on the column’s length, diameter, and phase. The molecules are then retained in the column for some time until the mass spectrometer captures, ionizes, accelerates, deflects, and detects those molecules according to their specific mass-to-charge ratios. The results are depicted in the form of a mass spectrum which is a plot of intensity having a mass to charge ratio as the function of it. A mass spectrometer is composed of an ionizing chamber, a mass analyzer, and finally a detector.


The sample is ionized by the bombardment of electrons. These ions are then directed towards the analyzer with the help of electric and magnetic fields and separated based on their mass to charge ratio. The ions having the same ratio will undergo the same amount of deflection. These charged particles are then detected by the aid of an electron multiplier (amplifier) and the results are displayed in the form of a mass spectrum.

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