Ancillary Methods

Abstract

Gas chromatography is among the most powerful of separatory methods available to the chemist and, for most purposes, it is a sufficiently precise means of quantitative analysis. However, it is a relatively poor qualitative tool. Even when techniques such as those described in Chapter 13 are used, identification of unknown compounds is relatively uncertain. Although identification methods are of little interest to the laboratory exclusively engaged in routine analysis, it is of utmost importance during the development of methods not only that the compounds of interest be thoroughly characterized but that the identity of the individual chromatographic peaks be unequivocally established. The elution of more than one component at the same time is relatively common and, obviously, the presence of any impurity in a peak of interest will affect quantitative accuracy. Furthermore, it is important to determine whether decomposition or rearrangement of the compounds of interest has occurred in the chromatographic system. Information of this sort can only be obtained by subjecting the components separated in the Chromatograph to further analysis; in this context the gas Chromatograph can be regarded as a purification method for the particular analytical technique to be employed.