Chiral separation of several amino acid derivatives by capillary zone electrophoresis with selectively acetylated β-cyclodextrin derivatives

Abstract

The chiral separation of five pairs of several amino acid enantiomers was examined by capillary zone electrophoresis using three selectively acetylated and methylated β-cyclodextrin (β-CD) derivatives. After acetylation of the hydroxyl groups of β-CD, its enantioselectivity completely disappeared for α- and β-naphthalenesulfonylamino acids. For dansylamino acids, several solutes were resolved only with heptakis(2,3-di- O-acetyl and 2,3-di- O-methyl)-β-CDs. The chiral recognition abilities of selectively acetylated and methylated β-CD derivatives were similar for dansylamino acids and α- and β-naphthalenesulfonylamino acids. Heptakis(3-mono- and 3,6-di- O-methyl)-β-CDs exhibited quite high chiral recognition abilities for α-naphthoylamino acids. On the other hand, β-naphthoylamino acids were resolved better in the presence of unmodified β-CD and heptakis(3-mono- and 3,6-di- O-acetyl)-β-CDs. Neither heptakis(2,3-di- O-acetyl nor 2,3-di- O-methyl)-β-CD could resolve α- and β-naphthoylamino acids at all.