Rapid analysis of amino acid enantiomers by chiral-phase capillary gas chromatography

Amino acids are derivatized with ethyl chloroformate or 2,2,2-trifluoroethyl chloroformate in a reaction medium containing different alcohols into a wide variety of N(O)-alkoxycarbonyl alkyl esters. The derivatives are produced to be used in a rapid separation of enantiomeric isomers by capillary GC with L-valine-tert.-butylamide-modified polydimethylsiloxane as chiral stationary phase. Among the various amino acid derivatives prepared, the N(O)2,2,2-trifluoroethoxycarbonyl 2',2',2'-trifluoroethyl ester gave fairly stable compounds and attained almost complete separation of all enantiomeric pairs, except for Pro, within 31 min. The derivatization method was found to be suitable for enantiomer separation rather than quantitative analysis.