Determination of aminitrozole, metronidazole, ornidazole and tinidazole adulterated in traditional chinese medicine by high performance liquid chromatography

Four antitrichomonal drugs, aminitrozole, metronidazole, ornidazole and tinidazole, adulterated in traditional Chinese medicine were assayed simultaneously by high performance liquid chromatography on an ODS column. This chromatographic method was carried out using isocratic elution with 0.01M phosphate buffer (pH 5.5) and acetonitrile (85:15). Calibration graphs of four adulterants were constructed in the range 0.02-0.20 mg/ml and their correlation coefficients calculated in the range 0.9998-0.9999. The recoveries of antitrichomonal drugs added to Gui-Chi-Hu-Lin-Wan were 87.5% for aminitrozole, 90.0% for metronidazole, 86.4% for ornidazole and 85.9% for tinidazole. The relative standard deviations for intraday and interday analyses were 1.5-1.6% and 2.6-5.7% (n=5), respectively. Tinidazole was detected and confirmed by TLC, UV and GC-MS from a herbal black pill that was consigned by The High Court on Sep. 1994. The assay of tinidazole was carried out by the HPLC method mentioned above. The recovery of tinidazole added to the traditional Chinese medicine was 103.9%. The content of tinidazole in the black pill was ranged from 3.1 to 4.4% (15.3-22.0mg in each pill).