Change of migration time and separation window accompanied by field-enhanced sample stacking in capillary zone electrophoresis

When field-enhanced sample stacking was used in capillary zone electrophore sis (CZE) analysis of cations, the decrease of migration time and the reduc tion of separation window was observed with increase of sample plug length. A simple equation expressing the migration velocity in the stacking proces s was derived to explain the above phenomenon. From experiments and theoret ical consideration, we confirmed that this effect was caused by the higher potential gradient and larger eletroosmotic flow (EOF) mobility at the samp le plug than those at the supporting electrolyte. A mathematical model appr opriate for the computer simulation of such a system was studied considerin g the experimental results, and it was concluded that electroosmotic veloci ty (v(eof)) should be introduced to the equation of continuity as a constan t.