Abstract: Separation of basic proteins was performed using a homemade electric field modu-lated capillary electrophoretic system, which can offer both radial and axial electric fields with only one high voltage power supply. The most interesting phenomenon observed is that the adsorption of protein molecules onto the tubing wall can be regulated by the application of a radial voltage(potential at the outer wall minus that at the inner wall): band broadening decreases with the increase of the radial voltage. This implies that it may be possible to dy-namically control the adsorption of protein molecules on silica surface. In addition, the radial voltage is also able to adjust the resolution of the solutes due to the change of electroosmosis.

Key words: Capillary electrophoresis, Protein separation, Radial electric field control