Separation of diastereomers by capillary zone electrophoresis in free solution with polymer additive and organic solvent component Effect of pH and solvent composition

Diastereomeric derivatives of enantiomers generally exhibit differences in their physico-chemical properties. This fact allows the separation of these compounds in non-chiral separation systems. Although charged diastereomers have been reported to be resolved in certain instances by capillary electrophoresis without any additives, a significant enhancement of stereoselectivity can be achieved by means of polymeric pseudophases. The present paper focuses on the influence of the pH and of the organic solvent component acetonitrile on the resolution of diastereomeric compounds in the absence and presence of a polymeric network of polyvinylpyrrolidone. Experimental data are presented for diastereomeric derivatives of cu-amino acids as well as for three anticoagulant drugs obtained by reaction with optically pure (+)-O,O'-dibenzoyl-L-tartaric anhydride.