Capillary electrophoresis of enantiomers and hydrophobic drugs using charged cyclodextrin derivatives.

Abstract

Electrokinetic chromatography (EKC), which belongs to one branch of capillary electrophoretic (CE) techniques, enables the separation of electrically neutral compounds by the CE technique through a chromatographic interaction, as in reversed-phase HPLC. In this study we employed several charged cyclodextrin (CD) derivatives as one of the pseudo-stationary phases for EKC. Because these CD derivatives have both chirality and charge, they can be applied to the separation of enantiomers and/or electrically neutral compounds. For more than 40 enantiomers, phosphated (α, β, γ)-CDs, sulfated β-CD, carboxymethylated (β, γ)-CDs, and carboxyethylated (β, γ)-CDs were tested under both acidic and neutralalkaline conditions in order to investigate the enantioselectivity. Among the tested charged CDs, β-type CDs were effective and about half of the analytes were enantioseparated by EKC with charged CDs, especially with β-CD phosphate or β-CD sulfate. Further, these charged CDs were applied to the separation of some cortico-steroids, such as triamsinolone acetonide. These charged CDs were found to be useful as one of the pseudo-stationary phases for EKC.