An on-line electrophoretic concentration method for capillary electrophoresis of proteins

A simple on-line electrophoretic concentration method for capillary electrophoresis of proteins with a semipermeable hollow fiber is proposed. A short, semipermeable hollow fiber is connected to the inlet end of a capillary. An injection electric field is applied across the hollow fiber. Protein samples are electromigrated into the hollow fiber from a sample vial. Since the protein ions cannot pass through wall of the hollow fiber, protein ions are concentrated in the hollow fiber. After a certain period of injection (concentration) time, an electric field is applied across the hollow fiber and the capillary, and a conventional CE is carried out. The concentration effect of the method has been demonstrated successfully with model protein samples, cytochrome c, lysozyme, ribonuclease A, and α-chymotrypsinogen A. Experimental results show that the concentration factor is increased with the injection (concentration) time and the electrophoretic mobility of the proteins. When the injection (concentration) tim...