Cyclodextrins as buffer additives for the enantiomeric separation of pinacidil in capillary zone electrophoresis

Abstract

The enantiomeric separation of pinacidil was studied using α-cyclodextrin (α-CD), β-CD, heptakis (2,6-di-O-methyl)-β-CD (DM-β-CD), hydroxypropyl-β-CD (HP-β-CD) and γ-CD as buffer additives at acidic pH in Capillary zone electrophoresis. β-CD, HP-β-CD and γ-CD all showed chiral recognition on the compound, with HP-β-CD giving the highest chiral selectivity. Buffer concentration and HP-β-CD concentration were optimized for the separation. The separation was improved by the addition of hydroxypropyl cellulose (HPC) to the buffer. A complete separation of pinacidil enantiomers was achieved by suing 100 m M Tris-H 3PO 4 buffer (pH 2.3) containing 9 m M HP-β-CD and 0.05% HPC.