A novel tentacle-type polymer stationary phase covalently modified with branched polyethyleneimine (PEI) was developed for peptides and proteins separations by open-tubular CEC (OT-CEC). The preparation procedure included the silanization of capillary inner wall, in situ graft polymerization and PEI functionalization. A wrinkly polymer surface of multitudinous steric amine groups was evenly formed on the capillary inner wall, and anodic EOF could be gained within a wide pH range of 2.5–7.5. The electroosmotic mobility was examined for its dependence on pH as well as PEI concentrations. Good repeatability was gained with RSD for the migration time of EOF marker within 4.8% and satisfactory chemical stabili... More
A novel tentacle-type polymer stationary phase covalently modified with branched polyethyleneimine (PEI) was developed for peptides and proteins separations by open-tubular CEC (OT-CEC). The preparation procedure included the silanization of capillary inner wall, in situ graft polymerization and PEI functionalization. A wrinkly polymer surface of multitudinous steric amine groups was evenly formed on the capillary inner wall, and anodic EOF could be gained within a wide pH range of 2.5–7.5. The electroosmotic mobility was examined for its dependence on pH as well as PEI concentrations. Good repeatability was gained with RSD for the migration time of EOF marker within 4.8% and satisfactory chemical stability was validated. Due to the existence of amine groups on the surface of tentacle-type polymer stationary phase, the silanol effect that occurs between the positively charged biomolecules and the silanols of the capillary column was greatly suppressed. Compared with a monolayer-coating capillary, seven enkephalin-related peptides were well resolved on the PEI-bonded column with high efficiencies. Favorable separations of peptides and proteins with high column efficiencies were obtained in 144 000–189 000 and 97 000–170 000 plates/m. Branched PEI-bonded tentacle-type polymer stationary phase has been proven to afford satisfactory retention and resolution of peptides and proteins.
