Poly(N-vinylimidazole)-grafted capillary for electrophoresis prepared by surface-initiated atom transfer radical polymerization

A CE method for poly(N-vinylimidazole) (PVI)-grafted capillaries by the surface-initiated atom transfer radical polymerization has been developed. The coating was prepared with N-vinylimidazole as the monomer, 2-bromo-2-methyl-N-[3-(triethoxysilyl) propyl] propanamide (BTPAm) as the initiator and CuCl/CuCl2/2,2'-bipyridine as the catalyst and ligand. The direction and magnitude of EOF in the PVI-grafted capillary were investigated in a pH range of 3.0-9.0. The results indicated that the EOF could be modulated by varying the pH value of the buffer and an anodic EOF was obtained at pH values below 6.5. A significant improvement in reproducibility and reduction of EOF appeared on the PVI-grafted capillary when compared with the uncoated capillary. Furthermore, the polymer coated capillaries were applied to the separations of the inorganic anions, organic acids and basic proteins and baseline separations were achieved with short analysis time and high reproducibility.