气相色谱法测定水产预混合饲料中肌醇含量的不确定度评定

Evaluation of uncertainty in determination of inositol in aquatic premix by gas chromatography

参照ISO/IEC Guide98-3-2008《测量不确定度表示指南》、CNAS-GL05:2011《测量不确定度要求的实施指南》及CNAS-GL06:2006《化学分析中不确定度的评估指南》,对气相色谱法测定水产预混合饲料中肌醇含量的测量不确定度进行了评定。通过建立测量模型、分析确定水产预混合饲料中肌醇的不确定度来源,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、回收率和重复测定等因素。对测量过程中的不确定度分量进行逐层分析与合成,当水产预混合饲料中肌醇含量为762 mg/kg时,得到其合成不确定度和扩展不确定度分别为81和162 mg/kg。结果表明,实验回收率、样品重复测定引入的不确定度分量对合成标准不确定度的贡献最大,样品称量引入的不确定度最小,标准曲线拟合带来的不确定度也不容忽视。本研究可为使用该方法测定水产预混合饲料中的肌醇含量的质量控制提供参考。

Abstract ： By referring to ISO / IEC Guide98 - 3 - 2008 ＂ Guide to the Expression of Uncertainty in Measurement ＂, CNAS- GLD5：2011 ＂Guidance on the Application of the Requirements for Measurement Uncertainty＂ and CNAS - GL06 ： 2006 ＂ Guidance on Evaluating the Uncertainty in Chemical Analysis＂ , the measurement uncertainty for deter- mination of inositol in aquatic premix by gas chromatography was evaluated. The measurement model of each compo- nent in the process of measurement was established. The main sources of uncertainty in the measurement process were the standard solution, the standard fitting curves by the method of linear least squares, the constant volume of sam- ples, sample weighing, spike recovery and repetitive test. The impact of every uncertainty component for the measure-ment uncertainty was estimated. Based on the quantitative analysis of every source, the relative standard uncertainty of measurement result was obtained. When the determination result of inositol in aquatic premix was 762 mg/kg, the combined standard measurement uncertainty and expanded measurement uncertainty were 81 and 162 mg/kg, respec- tively. The evaluation indicated that the spike recovery and repetitive test made the most contribution to the combined relative standard measurement uncertainty. The influence of standard curve fitting could not be neglected. The effect of sample weight was minimal. This evaluation provided a theoretical basis for the quality control of inositol content determination in aquatic premix.