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 silica as well as strong cation-exchange stationary phases. A mixed-mode separation mechanism was involved, comprising chromatographic interactions (adsorption, 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 include variations of the eluting strength and/or the concentration of the competing ion present in the background electrolyte. Using this approach, separation times could be shortened and changes in selectivity could be achieved for a number of analytes.