A REVIEW ON CAPILLARY ELECTROPHORESIS AND ITS APPLICATION FOR THE SEPARATION OF CHIRAL COMPOUNDS

Abstract

Capillary electrophoresis (CE) is a highly efficient analytical separation technique. Separation is based upon differences in mobility, which mainly depends on the charge to mass ratio of the molecule. The addition of an enantioselective complexing agent, or chiral selector, can change the charge to mass ratio of the enantiomers in a selective way resulting in mobility difference between the optical isomers which is a prerequisite for (chiral) separation. Optical isomers can be successfully separated if the mobility of the complex differs from the mobility of the free enantiomers and if the complex stability of the diastereomeric complexes is not identical. The stability of complexes between enantiomers and chiral selectors is expressed by their formation constants. The separation of the enantiomers of many compounds of pharmaceutical interest was investigated by CE, employing a soluble neutral β-cyclodextrin polymer as the chiral selector. Both selectivity and resolution were influenced by the concentration of the β-cyclodextrin polymer. CE is applied to determine the optical purity of a pharmaceutical formulation and also for the determination of drug enantiomers in human plasma.