Determination of metronidazole and norfloxacin in suppository by HPLC

A HPLC method was established for determining the concentrations of metronidazole and norfloxacin in suppository. A ��-Pondapak C18 column (3.9 mm x 300 mm, 10 ��m) was used with a mobile phase of methanol-phosphate buffer (25:75 ), which contains 10 mmol/L TBABr, 11 mmol/L H3PO4, 15 mmol/L KH2PO4 and pH = 2.75. The internal standard was used as enoxacin. The flow rate was 1.4 ml/min. A UV detector at 278 nm was used. The retention times of metronidazole norfloxacin and internal standard were 3.88 min, 7.10 min and 5.50 min respectively. The standard curves of metronidazole and norfloxacin were linear in the range from 2.0 to 26. 0 ��g/ml (r = 0.9995) and 1.0 to 13.0 ��g/ml (r = 0.9995) respectively. The average recoveries were 101.6% �� 0.7% (metronidazole) and 100.7% �� 1.2 (norfloxacin). This method is rapid, sensitive and specific. It is suitable for quality control of the suppository containing metronidazole and norfloxacin.