Gas-liquid chromatography and mass spectral analysis of mono-, di- and tricarboxylates as their tert.-butyldimethylsilyl derivatives.

A gas-liquid chromatographic (GLC) procedure is described which permits the baseline separation and quantitation of twenty saturated monocarboxylates, sixteen dicarboxylates (both alkanedioic and alkenedioic), and the tricarboxylates citrate and aconitate in a single GLC analysis. The carboxylic acids, as their tert.-butyldimethylsilylated derivatives, are readily separable on a SPB-1 (bonded) capillary column. Separation data on an OV-17 (bonded) capillary column and a SP-2250 packed column of these carboxylates, in addition to fifteen unsaturated carboxylates, are also given. The tert.-butyldimethylsilylation of carboxylic acids in their free or ammonium salt forms is accomplished in a single derivatization step with N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide. Retention data and responses for all mono-, di- and tricarboxylic acids are given. Mass spectral analysis of all tert.-butyldimethylsilylated carboxylic acids is presented and each displays a prominent and characteristic [M-57] fragment ion.