Behavior of basic compounds in ion-exchange capillary electrochromatography with low-pH carrier electrolytes

This work describes the separation of basic aromatic compounds by capillary electrochromatography employing acidic carrier electrolytes and bare silic a as well as strong cation-exchange stationary phases. A mixed-mode separat ion mechanism was involved, comprising chromatographic interactions (adsorp tion, ion-exchange) as well as electrophoretic migration. The influence of ion-exchange on the retention/migration of the solutes could be manipulated according to procedures commonly employed in ion chromatography. These inc lude variations of the eluting strength and/or the concentration of the com peting ion present in the background electrolyte. Using this approach, sepa ration times could be shortened and changes in selectivity could be achieve d for a number of analytes. (C) 2000 Elsevier Science B.V. All rights reser ved.