Application of capillary electrophoresis to predict crossover frequency of polystyrene particles in dielectrophoresis.

CE is used to calculate the zeta potential of polystyrene particles in order to estimate the surface conductivity of the particles. These values are used to predict the dielectrophoretic behavior, including the crossover frequency of particles under the influence of an AC electric field. Predictions for fluorescent polystyrene particles that are unmodified, carboxylate-modified, or streptavidin-modified are tested using miniaturized dielectrophoresis cells containing patterned gold quadrupole electrodes. The particle surface conductivities derived from CE separations differ from those derived from dielectrophoresis experiments by < or =0.003 S/m and serve as a guide to effectively select the suspending medium to generate a crossover frequency approximately 0.5 MHz. Prediction of dielectrophoresis crossover frequency is limited by several factors, especially the accuracy and precision of the conductivity measurements for the particle and suspending medium. A rapid analysis of particles by CE is a viable alternative to determine zeta potential.