Chiral Separation of the Enantiomers of Omeprazole and Pantoprazole by Capillary Electrophoresis

Abstract

We report systematic screening of different native and derivatized, charged and uncharged cyclodextrin (CD) derivatives for chiral separation, by capillary electrophoresis, of the enantiomers of omeprazole and pantoprazole, the two most frequently used proton-pump inhibitors. To optimize the analytical and electrophoretic conditions the effect of buffer composition, concentration, and pH, chiral selector type and concentration, potential, temperature, and injection volume were investigated. Baseline chiral separation was achieved by use of phosphate buffer at pH 2.5 and randomly methylated β-CD as chiral selector for omeprazole, and phosphate buffer at pH 7.0 and sulfobutyl ether-β-CD as chiral selector for pantoprazole. Of all the CD tested, sulfobutyl ether-β-CD was the only CD that interacted stereoselectively with both analytes at pH 7.0, but resolution of the enantiomers of omeprazole was only partial. The analytical performance of the optimized methods, in terms of repeatability, linearity, and limits of detection and quantification, was evaluated, and the methods were used for analysis of the enantiomers of these proton-pump inhibitors in pharmaceutical formulations.