Identification of Organic Compounds by Gas Chromatography

THE identification of unknown compounds separated by gas chromatography is often effected by comparison of their retention values with those of known compounds together with infra-red spectro-photometry or mass spectrometry. For this purpose graphs are prepared of log r against boiling point or log r on one stationary phase against log r on another stationary phase, where r is the retention time, relative retention time or the retention volume. Both non-polar and polar stationary phases are used to indicate the nature of the unknown substance. Wehrli and Kovats1have shown a relation between the structure of the substance and its retention values on two such phases. Stationary phase liquids which can take part in electron donor–electron acceptor interactions have also been used by Langer et al.2and Janak and Hrivnac3to separate closely similar pairs of compounds. I have also found4three different stationary phases to be useful in identifying components of a brown coal tar.