STUDIES OF MIGRATION TIME REPRODUCIBILITY OF CAPILLARY ELECTROPHORETIC PROTEIN SEPARATIONS

Studies of the migration time reproducibility of trypsinogen were performed using a capillary electrophoresis system designed for high resolution protein separations, where analyte adsorption and electroosmotic flow were minimized through the use of poly-(acrylamide)-derivatized capillaries coated with 3-(dimethyldodecylammonio)-propanesulfonate, a zwitterionic surfactant. The results of this investigation suggested that oxidation-induced pH drifts occurring at the electrodes had a significant impact upon protein migration. Acceptable migration time reproducibility (<2% RSD for a series of nine injections) was found to be dependent upon buffer replenishment at both electrodes prior to each injection. These results indicate that instruments which can provide preinjection buffer replenishment may be necessary for the qualitative or quantitative analysis of proteins using poly-(acrylamide) coated capillaries.