原子吸收法测定土壤中铅含量的不确定度评定

The Uncertainty Evaluation of Determining Lead in Soil with Atomic Absorption Method

以原子吸收法测定土壤中铅为例,本文分析了测试过程中不确定度的来源,对各不确定度分量进行评定及合成,并计算得出合成不确定度和扩展不确定度。结果表明,标准储备液配制过程引入的不确定度可以忽略不计,对本测试方法影响较大的不确定度分量是标准溶液稀释使用移液管的精度和微量进样器进样体积以及样品前处理和测定过程中的随机因素引起的相对不确定度。

With the atomic absorption method for determination of Pb in soil as an example, this article analyses the source of uncertainty in the testing process, evaluates and synthesizes every branch of uncertainty, and calculates the combined uncertainty and expanded uncertainty. The result shows that the uncertainty in the preparation process of standard solution can be ignored. However, this test method is greatly influenced by the following uncertainties： the precision of the pipette that used in dilution of standard solution, the volume of micro syringe and stochastic factors in sample pretreatment and determination.