ICP-MS法测定中药中铜、砷、镉、汞、铅含量的不确定度评定

目的对电感耦合等离子体质谱法(ICP-MS)测定中药材中铜、砷、镉、汞、铅含量的不确定度进行分析,以期找出影响不确定度的因素,为评价检验结果提供科学依据。方法用电感耦合等离子体质谱法测定中药中铜、砷、镉、汞、铅的含量,通过对测定方法流程进行分析,确定不确定度来源为样品称重、样品消解、稀释定容、仪器分析,并根据《测量不确定度评定与表示》(JJF1059-1999)中有关规定量化不确定度分量,计算合成不确定度。结果用ICP-MS法测定铜、砷、镉、汞、铅的扩展不确定度分别为铜0.08 mg.kg-1、砷0.06 mg.kg-1、镉0.012 mg.kg-1、汞0.016 mg.kg-1、铅0.14 mg.kg-1。样品溶液的制备过程、测定样品溶液中各元素的浓度是影响中药中重金属定量分析的测量不确定度的主要因素。结论在实际工作中,应选择最佳的消解方法,按规范做好标准溶液的配制、样品溶液的制备、仪器测量等几个步骤,以保证测量结果准确、可靠。测量不确定度的评定为评价分析结果的准确程度和方法的可靠性研究提供了参考。

Evaluation of uncertainty for the determination of Cu,As,Cd,Hg,Pb in TCM by ICP-MS

Objective To find out the influencing factors of uncertainty by analyzing the uncertainty for the determination of Cu, As, Cd, Hg and Pb in TCM by ICP - MS, and provide the evidence to evaluate the measurement. Methods To determine the content of Cu,As, Cd, Hg and Pb in TCM by ICP - MS, and analyze the flow - sheet of this method. The sources of uncertainty were arised from the procedure of analysis：weighing, sample digestion, diluting to volume and instrument analysis. To evaluate the uncertainty according to Evaluation and Expression of Uncertainty in Measurement （ JJF1059 - 1999 ） and calculate the synthesis uncertainty. Results The expanded uncertainties of the test were Cu 0.08 mg . kg- 1, As 0.06 mg. kg- 1 , Cd 0.12 mg0 kg-1 , Hg 0. 016 mg. kg-1 , Pd 0. 12 mg . kg-1 , respectively. The mainly influencing factors of uncertainty for the derermination of heavy metals in TCM were the sample preparation and the determination of the concentration of elements in test solution. Conclusions In order to get accurate and reliable results, the optimal digestion method should be chosen and the procedure such as preparation of standard solution, preparation of sample solution, instrument analysis should be operated according to the standard. The evaluation of uncertainty provided references for the accurate extent of analysis results and the reliability research of method.