Since each type of molecule has a different rate of progression, the various components of the analyte mixture are separated as they progress along the column and reach the end of the column at different times (retention time). The rate at which the molecules progress along the column depends on the strength of adsorption, which in turn depends on the type of molecule and on the stationary phase materials. As the carrier gas sweeps the analyte molecules through the column, this motion is inhibited by the adsorption of the analyte molecules either onto the column walls or onto packing materials in the column. In a GC analysis, a known volume of gaseous or liquid analyte is injected into the "entrance" (head) of the column, usually using a micro syringe (or, solid phase microextraction fibers, or a gas source switching system). Other parameters that can be used to alter the order or time of retention are the carrier gas flow rate, and the temperature. The function of the stationary phase in the column is to separate different components, causing each one to exit the column at a different time ( retention time). As the chemicals exit the end of the column, they are detected and identified electronically. A gas chromatograph uses a flow-through narrow tube known as the column, through which different chemical constituents of a sample pass in a gas stream (carrier gas, mobile phase) at different rates depending on their various chemical and physical properties and their interaction with a specific column filling, called the stationary phase. The British Beagle 2 Spacecraft which was intended to land on Mars in 2003 was outfitted with a gas chromatograph mass spectrometer (GC-MS) as part of its instrumentation package in order to detect carbon attributable to living organisms.Ī gas chromatograph is a chemical analysis instrument for separating chemicals in a complex sample. Archer John Porter Martin, who was awarded the Nobel Prize for his work in developing liquid-liquid (1941) and paper (1944) chromatography, laid the foundation for the development of gas chromatography and later produced liquid-gas chromatography (1950). German graduate student Fritz Prior developed solid state gas chromatography in 1947. 8.2 Gas chromatography columns and accessoriesĬhromatography dates to 1903 in the work of the Russian scientist, Mikhail Semenovich Tswett.8 Manufacturers of gas chromatographs, columns, and supplies.4.5 Column temperature and temperature program.4.3 Sample size and injection technique.4.1 Carrier gas selection and flow rates.
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