Epoxy resin coatings for capillary zone electrophoretic separation of basic proteins

Abstract

Epoxy resins, combining with a cross-linker, were coated on organosilanes modified fused-silica capillaries. After cross-linking, a tough three-dimensional network was attached to capillary surface via Si-O-Si-C bonds. The most effective coating consisted of epoxy resins cross-linked with diaminodiphenylmethane, which was stable over the pH range 2-12 and suppressed protein adsorption effectively. The electroosmotic flow was also greatly reduced and maintained constant over the pH range 6-10. High resolutions and separation efficiencies for basic proteins were obtained in the pH range 3-10 and reproducible separations were achieved from run to run and day to day.