A new technique to minimize the effects of turn-induced dispersion within U-shaped separation channels by using the field effect within a capacitor to vary the zeta potential along the channel walls in the vicinity of the microchannel is described. The effects of the separation channel geometry, the fluid velocity profile, and the use of the field effect to control the zeta potential on the band distribution in the detection area are extensively discussed. The results for a U-shaped separation channel indicate that varying the zeta potential by controlling the field effect significantly reduces the band dispersion induced by the 90degrees turns within the channel. Finally, it is shown that the application of the proposed localized zeta potential variation method also results in a correction of the band tilting phenomenon and a reduction in the racetrack effect.