RESUMEN
Objective To establish HPLC determination method and impurity profile of the related substances in metronidazole.Methods A Welch Ultimate(R)XB-C1s (4.6 mm× 250 mm,5 μm)was used with a mobile phase consisting of methanol-1.36 g· L-1 solution of potassium dihydrogen phosphate (20∶ 80).The detection wavelength was 315 nm and the flow rate was 1 mL· min-1.Its related substances were determined by principal component self-contrast method.Results Good separation of metronidazole and the impurities could be achieved.Twenty batches of samples in the past six years were determined which meet quality standards.The study of impurity profiles could effectively monitor the synthetic process and the change of impurities in metronidazole.Conclusion The method is simple,quick and sensitive,which can be used to control the related substances in metronidazole.Meanwhile,the impurity profiles ensure the quality stability of metronidazole.