Capillary zone electrophoretic separation of beta-blockers using citrate buffer at low pH

Ten beta-blockers were simultaneously separated by capillary zone electrophoresis using citrate buffer as a background electrolyte at low pH. The effects of buffer concentration and buffer pH on the migration behavior and separation of beta-blockers were systematically investigated. The results indicate that the resolution of co-migrating analytes improves with increasing buffer concentration at a low pH and that the optimum pH of the buffer decreases with increasing buffer concentration. Complete separation of the beta-blockers tested was achieved within a relatively short time with an appropriate concentration of citrate buffer in the range 160-400 mM and a proper pH in the range 3.0-1.8 using a 43 cm x 50 mu m I.D. fused-silica capillary at 15 kV.