离子选择电极法测定预混合饲料中氟的不确定度评定

对离子选择电极法测定预混合饲料中氟含量的测量不确定度进行了评定。通过建立测定过程中各分量的数学模型,分析、识别了不确定度来源,其不确定度主要来源于标准溶液、最小二乘法线性拟合曲线、定容体积、试样称量、回收率、重复测定等因素。在对各不确定度分量进行量化的基础上,合成得到了测定结果的相对不确定度。结果表明,重复测定、标准溶液和最小二乘法线性拟合曲线引入的不确定度对总不确定度贡献率最大,是影响该方法不确定度的主要因素,为采用该方法测定预混合饲料中氟含量的质量控制提供了理论依据。

Uncertainty Evaluation of Determination of Fluorine in Feed Premixes by Ion Selective Electrode Method

In this paper, the measurement uncertainty for determination of fluorine in feed premixes by ion selective electrode method was evaluated. The mathematical model of each component in the process of measurement was established. The main sources of uncertainty were analyzed and identified. The main sources of uncertainty in the process of measurement were the standard solution, standard linear fitting curves by the method of least squares, the total volume of samples test liquid, sample weighing, reference materials, spike recovery and repetitive test. 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. The evaluation indicated that major sources of uncertainty were repetitive test, standard solution and standard linear fitting curves by the method of least squares. This evaluation provided a theoretical basis for the quality control of fluorine content determination in feed premixes.