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Abstract. Solute migration in capillary electrophoresis is the sum of the molecularly specific electrophoretic mobility and the electric-field-induced solvent flow (electroosmosis). This solvent flow is an important component of capillary electrophoresis and has been linked to resolution and automation aspects of this technique. This work demonstrates that equivalent electroosmotic flows can be achieved using different buffer types if the ionic strength is equal in the two systems. The effects of the addition of acetonitrile and several different alcohols on electroosmotic flow are also examined. The data suggest a unique surface effect of alcohols on the observed electroosmotic flow.

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Abstract. The analytical capillary electrophoretic separation of polystyrene nanospheres is reported. Although these particles are negatively charged and possess intrinsic mobilities, their separations are based upon particle size with the smallest particles having the highest velocity through the capillary. Pretreatment of the capillary with a cationic surfactant is necessary to observe these separations. Interestingly, particles larger than about 700 nm in diameter cannot be observed to move through a 50-pmi.d. capillary, whereas particles as small as 39 nm in diameter can be resolved in this system. In contrast to normal electrophoretic separations, the mechanism of this process appears to be that of particlexapillary wall interaction as mediated by the adsorbed surfactant.

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