Behaviour 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.