Use of Surfactant Additives for Modification of Electroosmotic Flow and Wall Chemistry

Abstract

Addition of the zwitterionic surfactant CAS U to an electrophoretic buffer prevents interaction between cationic proteins and the capillary channel walls. It allows quantitative recovery of the proteins and yields efficiencies in excess of 750,000 plates per meter. In the presence of CAS U, the electroosmotic mobility is 90% suppressed. Further addition of a cationic surfactant such as CTAB allows control of the electroosmotic mobility. Variation in the CTAB-CAS U ratio allows monotonic control of the electroosmotic mobility in the reversed direction. This EOF control does not affect mobilities of cationic solutes such as benzylamine and lysozyme, and high efficiencies (>300,000 plates per meter) are maintained. However there is evidence suggesting that proteins are denatured by the CTAB.