CAPILLARY ELECTROCHROMATOGRAPHY - INVESTIGATION OF THE INFLUENCE OF MOBILE-PHASE AND STATIONARY-PHASE PROPERTIES ON ELECTROOSMOTIC VELOCITY, RETENTION, AND SELECTIVITY

The influence of mobile phase composition variation, organic solvent t ype, and the concentration of buffer salts on the magnitude of the ele ctroosmotic now (EOF) velocity, retention, and selectivity in capillar y electrochromatography (CEC) has been investigated systematically. Th e observed change in EOF is explained in terms of change of solvent an d stationary phase properties. These findings provide guidelines for t he practitioner to select optimal conditions for CEC separations. On t he other hand, it is demonstrated that stationary phase properties als o have a profound effect on EOF velocity, solute retention, and select ivity of separation. It is demonstrated that the column packed bed of silica-based reversed-phase particles is the main contributor to EOF i n CEC. Variation of stationary phases in CEC can be used in a similar way as in HPLC to improve the selectivity of separation of neutral sub stances. This also applies to the separation of weakly basic substance s like triazines. (C) 1997 John Wiley & Sons, Inc.