SEPARATION OF BASIC-PROTEINS BY CAPILLARY ZONE ELECTROPHORESIS WITH COATINGS OF A COPOLYMER OF VINYLPYRROLIDONE AND VINYLIMIDAZOLE

Capillary zone electrophoretic (CZE) separation of basic proteins has been achieved with capillary columns modified with copolymers of vinyl pyrrolidone (VP) and vinylimidazole (VI). The copolymerization reactio n is performed inside the capillary column and involves chemical bondi ng of the polymer to silica. The electroosmotic how (EOF) is greatly d ecreased by this surface modification. The presence of positive charge s on the coating surface, due to the cationic property of vinylimidazo le at pH below 7, reduces the adsorption of basic proteins onto the si lanol groups of the capillary surface. Acidic proteins are irreversibl y adsorbed, but rapid separation and good performance reproducibility are obtained with basic proteins. In the case of capillaries modified with VP, the acidic and basic proteins are eluted within 10 min. In th is work, we studied the effects of pH and buffer concentration on the magnitude of the EOF, as well as the effect of copolymer composition o n the separation efficiency.