微波消解-原子荧光法测定土壤中砷含量的不确定度评估

Evaluation of Uncertainty in Determination of Arsenic in Soil by Microwave Digestion-Atomic Fluorescence Method

采用微波消解-原子荧光法测定土壤中砷含量,对测定过程中测量不确定度分量进行识别。建立该方法测定土壤中砷元素的数学模型,分析不确定度的来源主要包括样品称量过程、样品移取定容过程、砷标准系列、仪器校准以及样品重复测定,对引入的各不确定度分量进行了分析计算。对比各不确定度分量大小发现,此次测量不确定度主要源于样品重复测定引入的不确定度。通过合成可得到测量结果的合成不确定度、扩展不确定度及测试结果的报告形式。通过采用本实验方法测定土壤样品中砷的含量,称样平均质量为0.1576g,取置信水平为95%,包含因子k=2,测定结果为(25.5±1.9)mg/kg。

The microwave digestion-atomic fluorescence method was used to determine arsenic content in soil.The measurement uncertainty component was identified during the measurement. Method to establish the mathematical model was developed for the determination of arsenic in soil. The sources of analytical uncertainty mainly include sample weighing process, sample removal and constant volume process, arsenic standard solution and preparation of standard solution, instrument calibration and sample repeated determination.The introduced uncertainty components was analyzed and calculated. By comparing the size of each uncertainty component,The uncertainty of this measurement mainly came from the uncertainty introduced by repeated measurement of samples. The synthetic uncertainty, the extended uncertainty and the report form of the test results was obtained through the synthesis. The arsenic content in soil samples was determined by this method,the average mass of samples was 0.1576g, the confidence level was 95%, the inclusion factor K =2, and the determination result was(25.5±1.9) mg/kg.