ICP-MS测定化药甲硝唑中铅的不确定度分析与评定

Assessment and Analysis of Uncertainty in ICP-MS Measurement of Lead in Metronidazole Pharmaceuticals

采用电感耦合等离子体质谱法(ICP-MS)对化学药品甲硝唑中的铅含量开展不确定度来源分析及评定。测试按照《中华人民共和国药典》(2020版)四部通则2321法,甲硝唑样品经微波消解处理后采用ICP-MS测定铅含量,考察样品称量、微波消解定容、标准工作溶液的配制、标准曲线回归拟合、重复性测定等各因素的相对不确定度,形成合成不确定度及扩展不确定度。在ICP-MS测定化学药品甲硝唑中铅含量的测试中,对不确定度结果贡献最大的因素是标准工作溶液的配制,相对不确定度为1.44%;样品称量、微波消解定容、重复性测定等环节引入的相对不确定度对不确定度结果值贡献较小。当称样量为0.10 g时,所测化学药品甲硝唑片中铅含量为0.5063μg/g,其扩展不确定度为0.01793μg/g(k=2)。

This study investigates the sources of uncertainty in determining the lead content in metronidazole pharmaceuticals using inductively coupled plasma mass spectrometry(ICP-MS).Following the 2321 method of the Pharmacopoeia of the People’s Republic of China(2020 edition),lead content was measured using ICP-MS post-microwave digestion.The study analyzed the uncertainty contributed by sample weighing,microwave digestion,preparation of standard working solutions,regression fitting of the standard curve,and repeatability of measurements to establish combined and expanded uncertainties.The findings indicate that the preparation of standard working solutions is the primary contributor to uncertainty,with a relative uncertainty of 1.44%.Other factors such as sample weighing,microwave digestion,and repeatability have a lesser impact on the overall uncertainty.For a sample weight of 0.10 g,the lead content in metronidazole tablets was found to be 0.5063μg/g,with an expanded uncertainty of 0.01793μg/g(k=2).