Preparation of Capillary Electrophoresis Column Physically Coated with Hyperbranched Polyesters and Its Application in the Separation of Basic Proteins

Two series of hyperbranched polyesters were synthesized using pentaerythritol as the core by one-step and pseudo-step procedures. The molecular structures of the hyperbranched polyesters were characterized using infrared spectrum and hydroxyl value. Due to their low viscosity, the hyperbranched polyesters were easily coated on the inner surface of the fused-silica capillary by physical adsorption. The adsorption behavior of this capillary electrophoresis column coated with polyesters was investigated by the separation of three basic proteins. The electro-osmotic flow and the capability for the separation of the basic proteins were studied. It was found that the coatings of hyperbranched polyesters could significantly reduce the electro-osmotic flow and suppress the protein adsorption onto the inner surface of the fused-silica capillaries in the pH range of 3–7. Three basic proteins were effectively separated at pH = 5 on the column coated with the hyperbranched polyesters, with the separation efficiency being 105 plates/m. The experimental results also showed that the separation efficiency and the resolution on columns coated with hyperbranched polyesters by pseudo-step procedure were much better than those by one-step procedure.