Non-bonded 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 is first filled with 1 M HCl solution, then flushed with 0.2% poly(ethylene 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 separated by this method around pH 3-7 with phosphate buffer. The separation efficiency in terms of peak shape was excellent compared to bare fused-silica capillaries and comparable to many other more sophisticated column-treatment methods. The reproducibility of migration times of 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 the structure of poly(ethylene oxide) are important factors to form a stable coating via hydrogen bonding to the surface silanol groups.