Preparation And Applications Of Covalently Bonded Capillaries For Capillary Electrophoresis

Column technology is one of the most important parts of capillary electrophoresis. Various kinds of coated capillary columns are playing a more and more important role in eliminating the analyte-wall interactions and in alternating the electroosmotic flow to result in more rapid separation, improved reproducibility or resolution. Covalently bonded capillary columns have the advantage of long-term stability and flexible manipulation conditions and have gained popularity in different applications. However, methods for preparing those columns generally involve multi-step procedures with low successful rate and high cost. Therefore, new protocols to prepare the covalently bonded capillary columns efficiently and effectively are in demand.A novel and convenient protocol for the preparation of polyethyleneimine coated column was developed here in which trimethoxysilane-modified polyethyleneimine was synthesized withγ-glycidoxypropyltrimethoxysilane and polyethyleneimine first and then chemically bonded onto the inner surface of commercial available fused-silica capillary under heating treatment. For comparison, chemically bonded epoxy-based coating was prepared by multi-step procedures. These two capillaries were evaluated for their performance in the magnitude of electroosmotic flow and in the separation of basic proteins, acidic proteins and anions. Applications of coated capillary columns in enzyme assay, separation of basic peptide and chiral drugs were also performed.The polyethyleneimine coated capillary column prepared by the above-mentioned new method effectively suppressed the electroosmotic flow and eliminated the adsorption of basic proteins onto the inner surface of capillary wall. Good separations of basic and acidic proteins as well as inorganic and organic anions were obtained when compared with the epoxy-based capillaries. The analyses were all with good reproducibility. The application of enzyme assay, separation of peptide and chiral drugs were also successful performed in these covalently coated capillary columns.The capillary columns developed in this study exhibited a long-term stability which is in line with the expectation of the covalently bonded coatings. The one step...