Since gas-liquid chromatography (GLC) has been the major an alytical technique used in these studies, the combined term GLC-chemotaxonomy appears in the microbiological literature. Gas chromatography encompasses a number of chromatographic methods, all of which have gas as the moving or mobile phase. It is a method whereby components of a volatile mixture are separated by distribution between two phases: one a stationary phase over which the second, a gas phase, flows. The function of the column oven is to house the analytical column. The column ovens of commercial instruments are designed to accommodate either coiled or U-shaped columns. Several detectors can be used in gas chromatography, but only the thermal conductivity, the flame ionization, and the electron-capture detector have been used extensively in microbiology. Several procedures have been used to remove fatty acids from bacterial cells and convert them to volatile derivatives for subsequent analysis by GLC.