Enhanced selectivity for capillary zone electrophoresis using ion-pair agents
Shelton, C. M.; Koch, J. T.; Desai, N.; Wheeler, J. F. Enhanced selectivity for capillary zone electrophoresis using ion-pair agents. J. Chromatogr. A 1997, 792, 455-462.
Capillary zone electrophoresis (CZE) is unique in its simplicity and versatility for liquid separations, yet selectivity for solutes with similar charge and hydrated radius is often lacking. Conventional reversed-phase liquid chromatography (RP-LC) ion-pairing agents, ionic polymers, Group I and II metal cations and dicarboxylic acids have all been effectively used over the past decade to enhance CZE resolution through a combination of complexing effects. This review summarizes the fundamental theory of ionâ€“ion interaction as applied to CZE separations and discusses several of the most important and diverse applications of selectivity enhancement that utilize ion-pair equilibria. In addition, the effect of ion-pair additives on electroosmotic flow and examples where changes in analyte selectivity are unrelated to ionâ€“ion interaction are discussed.
Journal of Chromatography A