NONBONDED POLY(ETHYLENE OXIDE) POLYMER-COATED COLUMN FOR PROTEIN SEPARATION BY CAPILLARY ELECTROPHORESIS

A simple method to coat a non-ionic hydrophilic polymer onto the inner wall of a bare fused-silica capillary is established. The capillary i s first filled with 1 M HCl solution, then flushed with 0.2% poly(ethy lene oxide) solution containing 0.1 M HCl, and finally rinsed with the electrophoretic buffer. Each step takes only 5 min. For regeneration of the coating, this procedure is repeated. Four basic proteins were s eparated by this method around pH 3-7 with phosphate buffer. The separ ation efficiency in terms of peak shape was excellent compared to bare fused-silica capillaries and comparable to many other more sophistica ted column-treatment methods. The reproducibility of migration times o f proteins was less than 3% R.S.D. at pH 6 by manual operation of the coating process. Titration of the fused-silica surface with acid and t he structure of poly(ethylene oxide) are important factors to form a s table coating via hydrogen bonding to the surface silanol groups.