电感耦合等离子体质谱法测定蒙脱石中铅和砷含量的不确定度评定

Uncertainty evaluation for the determination of Pb and As in montmorillonite by inductively coupled plasma mass spectrometry

目的评定电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)测定蒙脱石中有害元素铅(Pb)和砷(As)含量的不确定度。方法采用硝酸回流提取-电感耦合等离子体质谱法测定蒙脱石中Pb和As的含量。通过分析测定流程,确定不确定度的来源,并计算各不确定度分量和合成不确定度、扩展不确定度。结果 ICP-MS法测定蒙脱石中铅和砷含量的扩展不确定度为Pb 0.109 mg/kg,As 0.020 mg/kg。结论测定结果的不确定度主要来源于方法回收率、标准溶液配制及标准曲线拟合,而供试品取样称量、定容、方法重复性的影响几乎可以忽略不计。

Objective To evaluate the uncertainty for the determination of Pb and As in montmorillonite by inductively coupled plasma mass spectrometry(ICP-MS). Methods Pb and As content in montmorillonite was extracted by nitric acid solution and quantitatively detected by ICP-MS. The determination process was analyzed to identity the source of uncertainty,then the individual components of uncertainty were evaluated and the combined uncertainties and expanded uncertainties were calculated. Results The expanded uncertainty of determination was 0.109 mg/kg for Pb and 0.020 mg/kg for As. Conclusion The uncertainty of determination results mainly comes from the method recovery rate,standard solution preparation and standard curve fitting,while the influence of sample weighing,constant volume and method repeatability can be ignored.