Enantioselective separation of unusual amino acids by high performance liquid chromatography

Unusual amino acids, i.e. amino acids not encoded by DNA, play fundamental roles in many scientific fields. Since the single enantiomeric form can cause different and often serious response of organisms, chiral separations of unusual amino acids are irreplaceable tools in their study and their employment. Two types of chiral stationary phases, two teicoplanin-based and four polysaccharide-based columns, were used. Separation conditions of reversed phase mode, polar organic mode and hydrophilic interaction chromatography were evaluated and compared. All columns used exhibited significantly different enantioselectivities. Teicoplanin-based chiral stationary phases, especially Chirobiotic T column, were able to separate almost all enantiomers tested, with the exception of Z-D,L-4-F-phenyl alanine ethyl ester. No partial enantioseparation of this analyte was obtained on teicoplanin-based chiral stationary phases, while baseline enantioresolution was achieved on polysaccharide-based columns. Change of elution order of and D-enantiomers was proved regarding the chiral stationary phase used. (C) 2013 Elsevier B.V. All rights reserved.