SUPPRESSION OF ELECTROOSMOTIC FLOW AND PREVENTION OF WALL ADSORPTION IN CAPILLARY ZONE ELECTROPHORESIS USING ZWITTERIONIC SURFACTANTS

Addition of zwitterionic surfactants such as dodecyldimethyl(3-sulfopr opyl)ammonium hydroxide, hexadecyldimethyl(3-sulfopropyl)ammonium hydr oxide, and coco (amidopropyl)hydroxyldimethylsulfobetaine (Rewoteric A M CAS U) to an electrophoretic buffer suppress the electroosmotic flow by 50-90%. Onset of suppression occurs at approximately the critical micelle concentration of the surfactant. CAS U effectively suppresses the electroosmotic now over the pH range 3-12. Addition of 2 mM CAS U to the electrophoretic buffer prevents adsorption of cationic proteins lysozyme, alpha-chymotrypsinogen A, cytochrome c, and ribonuclease A. Migration time reproducibility for these proteins is similar to 1% RS D within 1 day and 2-5% from day to day. Efficiencies in excess of 750 000 plates/m and recoveries of >80% were observed for protein injectio ns from distilled water. Alternatively if 2 mM CAS U is added to sampl es, recoveries were quantitative, although efficiencies decreased to 3 25000-600000 plates/m. The natural electroosmotic now of the capillari es is regenerated simply by rinsing with sodium hydroxide.