Cellulose acetate-coated fused-silica capillaries for the separation of proteins by capillary zone electrophoresis

Abstract

Thin-film coatings of cellulose acetate on the surface of fused-silica capillaries were tested for the separation of proteins by capillary zone electrophoresis. The coating procedure is very simple and only involves the filling of the capillary with cellulose acetate solution, followed by flushing the capillary with helium. The coating appears to mask the underlying silanol groups towards basic proteins effectively; column efficiencies up to 10 6 plates per metre were achieved for ribonuclease A. The high efficiency, the batch-to-batch and the run-to-run reproducibility and the long-term stability of the coating are advantageous features of the method. The coating procedure provides a simple, stable and easy to reproduce method of surface deactivation and can be applied with other cellulose derivatives such as cellulose triacetate or cross-linked hydroxypropylcellulose. The films can also be applied to shield the surface of hollow polypropylene fibres. Unfortunately, this skin coating is destroyed above pH 7.5 and therefore cannot be recommended for zone electrophoresis at alkaline pH or for isoelectric focusing.