Migration behaviour and separation of acetaminophen and p-aminophenol in capillary zone electrophoresis: analysis of drugs based on acetaminophen

The migration behaviour of acetaminophen and p-aminophenol was investigated by capillary electrophoresis. The influence of different parameters (pH, nature and concentration of the running buffer and applied voltage) on the migration time, peak symmetry, efficiency and resolution was systematically investigated. The two analytes can be well separated within 4 min in a 57 cm fused-silica capillary at a separation voltage of 18 kV in a 50mM borate buffer adjusted to pH 9.5. Correlation coefficients for calibration curves in the range 0.2-200 microg ml-1 for acetaminophen and 0.3-3 microg ml-1 for p-aminophenol were higher than 0.999. The sensitivity of detection is 4.2 ng ml-1 for acetaminophen and 11.2 ng ml-1 for p-aminophenol. The method was applied to the analysis of various commercially available acetaminophen dosage forms with recoveries of 98.4-100.7%.