The study of enantioselectivity of all regioisomers of mono-carboxymethyl-β-cyclodextrin used as chiral selectors in CE

This work documents the influence of the position of single carboxymethyl group on the β-cyclodextrin skeleton on the enantioselectivity. These synthesized monosubstituted carboxymethyl cyclodextrin (CD) derivatives, native β-cyclodextrin, and commercially available carboxymethyl-β-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 β-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 β-cyclodextrin. Comparable results to native β-cyclodextrin were obtained for 6(I)-O- regioisomer and the enantioselectivity of 3(I)-O-regioisomer was even worse than with native β-cyclodextrin. Commercially available derivative of CD provides better resolutions than the monosubstituted carboxymethyl CD derivatives for most of the investigated analytes.