高氯酸湿消化-原子荧光光度法测定饲料中总砷的不确定度评定

Uncertainty Evaluation of Determination of Total Arsenic in Feeds by Atomic Fluorescence Spectrometry after Perchloric Acid Wet Digestion

对高氯酸湿消化法处理饲料样品后用原子荧光光度法测定总砷含量的测量不确定度进行了评定。通过建立测量过程中各分量的数学模型,分析、识别了不确定度来源,其测量不确定度来源于样品测试液总体积、样品称量、样品重复测定、回收率、标准物质、标准曲线等因素,估算出各不确定度分量对测量不确定度的影响,在对各不确定度分量进行量化的基础上,合成得到了测量结果的相对标准不确定度。结果表明,样品重复测定和回收率,是影响该方法不确定度的主要因素,从而为采用该方法测定饲料中总砷含量的质量控制提供了理论依据。

To evaluate the measurement uncertainty for determination of total arsenic in feeds by hydride generation -atomic fluorescence spectrometry after perchloric acid wet digestion treatment, the mathematical model of each component in the process of measurement was established. The main sources of uncertainty were analyzed and identified. The sources of uncertainty in the measurement process were the total volume of samples test liquid, sample weighing, repetitive test of samples, spike recovery, reference materials and standard curves. The impact of every uncertainty component for the measurement uncertainty was estimated. Based on the quantitative analysis of every source, the relative standard uncertainty of measurement result was obtained. Results：The evaluation indicates that major sources of uncertainty are repetitive test and recovery of samples. This evaluation provides a theoretical basis for the quality control of total arsenic content determination in feeds.