Capillary electrochromatography for separation of peptides driven with electrophoretic mobility on monolithic column

A mode of capillary electrochromatography for separation of ionic compounds driven by electrophoretic mobility on a neutrally hydrophobic monolithic c olumn was developed. The monolithic column was prepared from the in situ co polymerization of lauryl methacrylate and ethylene dimethacrylate to form a C-12 hydrophobic stationary phase. It was found that EOF in this hydrophob ic monolithic column was very poor, even the pH value of mobile phase at 8. 0. The peptides at acidic buffer were separated on the basis of their diffe rences in electrophoretic mobility and hydrophobic interaction with the sta tionary phase; therefore, different separation selectivity can be obtained in CEC from that in capillary zone electrophoresis (CZE). Separation of pep tides has been realized with high column efficiency (up to 150 000 plates/m eter) and good reproducibility (migration time with RSD < 0.5%), and all of the peptides, including some basic peptides, showed good peak symmetry. Ef fects of the mobile phase compositions on the retention of peptides at low pH have been investigated in a hydrophobic capillary monolithic column. The significant difference in selectivity of peptides in CZE and CEC has been observed. Some peptide isomers that cannot be separated by CZE have been su ccessfully separated on the capillary monolithic column in this mode with t he same buffer used.