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Derivatization of chiral amino acids in supercritical carbon dioxide.

A new method is proposed to perform the derivatization of chiral amino acids occurring in complex samples using supercritical carbon dioxide as both the reaction medium and the agent used to extract the obtained derivatives prior to accomplishing the subsequent enantiomeric chromatographic analysis. The derivatization step under supercritical conditions involves the esterification of the carboxyl group and the acylation of the amino group of the amino acids without using a catalyst. A Chirasil-L-Val capillary column enabled the separation of the D- and L-forms of the amino acids as their N(O)-pentafluoropropionyl 1-propyl esters. Relative standard deviation values obtained from the gas chromatographic analysis for the derivatized amino acids ranged from 5 to 15%.