ENANTIOMER SEPARATION OF AMINO-ACIDS BY CAPILLARY GAS-CHROMATOGRAPHY USING CYCLODEXTRIN DERIVATIVES AS CHIRAL STATIONARY PHASES

Amino acids were derivatized to N(O)-trifluoroacetyl methyl and isopropyl esters and studied with respect to the gas chromatographic separation of their enantiomers by using capillary columns coated with four types of cyclodextrin derivatives of 6-O-tert.-butyldimethylsilyl-2,3-di-O-acetyl or n-butyryl-beta and -gamma-cyclodextrin. All amino acids could be separated into enantiomeric pairs except Trp. Methyl ester derivative showed the best separation on octakis(2,3-di-O-n-butyryl-6-O-tert.-butyldimethylsilyl)-gamma-cyclodextrin and isopropyl esters on heptakis(2,3-di-O-acetyl-6-O-tert.-butyldimethylsilyl)-beta-cyclodextrin. Pro showed complete separation as its N(O)trifluoroacetyl isopropyl ester derivative, and the same derivative of Ala showed a very high separation factor of 1.808 at 100 degrees C.