Capillary electrophoresis with electrochemical detection for chiral separation of optical isomers

The enantiomers of two amine derivatives were directly separated by capillary electrophoresis (CE), employing β-cyclodxtrin (β-CD) as a chiral additive in strongly alkaline solutions. The analytes were detected by electrochemistry, using a copper disk electrode at +675 mV vs Ag/AgCl reference electrode. Both the free enantiomers and the enantiomer-cyclodxtrin inclusion complexes could be detected using this approach, although the complexed forms gave lower oxidation currents than the free forms. Factors affecting the chiral CE separation of the analytes, such as working potential, concentration of running buffer and β-CD, and applied voltage, were extensively investigated. Under the optimum conditions, baseline separation of the enantiomers could be accomplished in less than 18 min. In addition, a successful application of the method to the enantiomeric purity determination confirmed its validity and practicability.