全自动消解-ICP-MS法测定土壤镉铅的不确定度评定

Uncertainty Evaluation of Determination of Cadmium and Lead in Soil by Full-automation Digestion-Inductively Coupled Plasma Mass Spectrometry

采用全自动消解-电感耦合等离子体质谱法(ICP-MS)测定土壤中镉和铅的含量,对测定过程中不确定度的来源进行分析,按照《测量不确定评定与表示》(JJF 1059.1—2012)评估各不确定度,并将各分量进行了合成。结果表明:镉的测量不确定度主要来源于标准溶液配制、样品消解和标准曲线拟合,铅的测量不确定度主要来源于标准溶液配制和样品消解。当土壤中镉和铅的浓度分别为0.51 mg/kg和60.6 mg/kg时,在95%置信水平下,扩展不确定度分别为0.03 mg/kg和2.5 mg/kg(k=2)。

The soil sample was digested by full-automation digestion and the conternt of cadmium and lead was determined by inductively coupled plasma mass spectrometry(ICP-MS). The sources of uncertainty in the measurement process were analyzed. The uncertainty was estimated and combined according to the Evaluation and Expression of Uncertainty in Measurement(JJF 1059.1—2012). The results show that the sources of uncertainty in the measurement of cadmium are mainly from the preparation process of the standard solution, the digestion process of the sample and the fitting of the standard curve, and the sources of uncertainty in the measurement of lead are mainly from the preparation process of the standard solution and the digestion process of the sample. When the contents of cadmium and lead are 0.51 mg/kg and 60.6 mg/kg, the expanded uncertainties are 0.03 and 2.5 mg/kg(k= 2) at the 95% confidence level, respectively.