ANALYSIS OF DOXYCYCLINE BY CAPILLARY ELECTROPHORESIS

Doxycycline is a semi-synthetic broad spectrum antibiotic with improve d serum half-life. Potential impurities are 4-epidoxycycline, 6-epidox ycycline, 4,6-epidoxycycline, metacycline and 2-acetyl-2-decarboxamido doxycycline. Method development has been undertaken to investigate the potential of capillary electrophoresis for the analysis of doxycyclin e. The influence of buffer type, buffer pH and concentration was syste matically examined, then that of capillary temperature and applied vol tage. All the potential impurities could be separated at 15 degrees C on a 44 cm x 50 mu m I.D. fused silica capillary (effective length to detector, 38 cm) with sodium carbonate (70 mM) - EDTA (1 mM), pH 10.50 , as background electrolyte and with a voltage of 12 kV. The relative standard deviation was 2.2 % for doxycycline. The limit of detection a nd quantification for doxycycline were 0.2 and 0.4 %.