CHLOROFORMATES IN GAS-CHROMATOGRAPHY AS GENERAL-PURPOSE DERIVATIZING AGENTS

Chloroformates with simplest alkyls, i.e. methyl, ethyl or isobutyl, a lready known as favourable reagents for treating amino groups in gas c hromatography for years, were revealed randomly as exceptionally rapid esterification agents. Unlike the rather poor results achieved with c hloroformate-mediated ester formation in organic chemistry, the pyridi ne-catalyzed esterification of carboxylic acids appeared to proceed at the analytical microscale smoothly. Along with the catalyzer, an alco hol should also be present in the medium, accompanied by acetonitrile or water, according to the character of the compounds treated. Reactio n conditions were optimized for various classes of carboxylic acids an d a uniquely rapid derivatization of amino acids in aqueous ethanol wa s shown to be possible. Most of the analytes, e.g. acidic metabolites in physiological fluids, could be treated directly in the aqueous matr ix. A simultaneous analysis of, e.g., amino and fatty acids or amines and their acidic catabolytes was proven to be possible. Along with the low-molecular-mass reagents, still some others, i.e, the hexyl, menth yl or pentafluorobenzyl ones, found their application fields. Results of optimized reaction conditions and a wide range of applications of c hloroformate-mediated derivatization in various disciplines have been summarized in this review. (C) 1998 Elsevier Science B.V. All rights r eserved.