Enantioseparation of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate-derivatized amino acids by capillary zone electrophoresis using native and substituted beta-cyclodextrins as chiral additives .2. Evaluation of complexation constants

Enantioseparation of amino acids derivatized with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) reagent by capillary zone electrophoresis (CZE) is reported using native and four substituted beta-cyclodextrins as chiral selectors added to the background electrolyte. The substituted selectors were (2-hydroxy)propyl-beta-cyclodextrin, heptakis(2,6-di-O-methyl)-beta-cyclodextrin, heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin and beta-cyclodextrin polymer. The selectors were compared with respect to the enantioselectivity coefficients obtained at optimum selector concentrations, Complexation constants were evaluated for six amino acids from curve fitting procedures. For the complete set of amino acids approximate complexation constants were predicted assuming constant complex mobilities for amino acids of similar size. Limited correlation was found between strength of complexation and achieved enantioselectivity.