The study of enantioselectivity of all regioisomers of mono-carboxymethyl-beta-cyclodextrin used as chiral selectors in CE
Abstract
This work documents the influence of the position of single carboxymethyl group on the beta-cyclodextrin skeleton on the enantioselectivity. These synthesized monosubstituted carboxymethyl cyclodextrin (CD) derivatives, native beta-cyclodextrin, and commercially available carboxymethyl-beta-cyclodextrin with degree of substitution approximately 3 were used as additives into the BGE consisting of phosphate buffer at 20 mmol/L concentration, pH 2.5, and several biologically significant low-molecular-mass chiral compounds were enantioseparated by CE.
The results indicate that different substituent location on beta-cyclodextrin skeleton has a significant influence on the enantioseparation of the investigated enantiomers. The enantioselectivity of 2(I)-O-regioisomer was better than with native beta-cyclodextrin.
Comparable results to native beta-cyclodextrin were obtained for 6(I)-O-regioisomer and the enantioselectivity of 3(I)-O-regioisomer was even worse than with native beta-cyclodextrin. Commercially available derivative of CD provides better resolutions than the monosubstituted carboxymethyl CD derivatives for most of the investigated analytes.