STABLE PHASES FOR CAPILLARY ELECTROPHORESIS

Three phases for use in capillary electrophoresis, two bonded hydrophobic phases and one bonded hydrophilic phase, were characterized as to stability over time at neutral pH, effect on electroosmotic flow velocity, effect on electroosmotic flow velocity changes with pH, and ability to provide protein separations not possible with untreated silica under the same conditions. All columns demonstrated stability comparable to bare silica at pH 7.0, over more than 50 continuous runs. The hydrophobic phases reduced the electroosmotic flow by 37 to 43% and minimized the change in electroosmotic flow velocity with changing pH over a pH range of 3 to 10. Protein separations were achieved from pH 6 to 9.3. Changes in pH over the above range were used to optimize these separations without changing electroosmotic flow characteristics.