A covalent modified hydrophilic capillary for enhanced capillary electrophoresis of biopolymers

δ-Gluconolactone was covalently coupled to aminopropyl derivatized capillary, which created hydrophilic brushes on the inner wall of the capillary. The coated capillary was shown to generate a stable electroosmotic flow (EOF) in the investigated pH range of 2.0-9.0 and to suppress effectively the adsorption of proteins. And it enabled separation of some biopolymer mixtures including basic proteins, DNA and tryptic digested bovine serum albumin (BSA) within 15 min with efficiencies up to 450,000 plates/m. The intra- and inter-day reproducibility of the coating referring to the retention times of proteins were satisfactory with mean relative standard deviations (R.S.D.) of 0.8 and 1.7%, respectively.