Capillary Zone Electrophoresis (CZE) is probably the simplest and perhaps the most universally useful mode of High Performance Capillary Electrophoresis (HPCE), which combines the strengths of both conventional electrophoresis in resolving power and High Performance Liquid Chromatography (HPLC) in the ease and speed of analysis. A fundamental problem in CZE is to directly control the zeta potential at the aqueous/capillary interface. Director control of the zeta potential is essential for manipulating the electroosmotic flow inside the capillary and the adsorption of macromolecules onto the capillary wall. An instrumentation method involving the use of an additional electric field from outside the capillary for controlling the zeta potential is therefore proposed in this study. The fundamentals of this approach will be studied both experimentally and theoretically with the proposed capacitor model. Significant improvements of separation efficiency and resolution of protein mixtures and DNA fragments for both qualitative and quantitative applications will then be demonstrated and achieved.
