电感耦合等离子体质谱法测定猪肉中总砷的不确定度

【目的】对基于GB 5009.11—2014《食品安全国家标准食品中总砷及无机砷的测定》方法测定猪肉中总砷的不确定度,探讨各不确定度分量的影响,以提高实验结果的准确性。【方法】对测量过程中影响测定结果的不确定度来源包括重复性测量、样品称量、样品稀释、标准品质量浓度、标准曲线等进行不确定度评估。采用A类评定评估测定重复性测量引入的不确定度,由其他因素引起的不确定度采用B类评定评估。根据各分量计算相对合成标准不确定度以及相对扩展不确定度,探讨各不确定度分量对测定结果的影响。【结果】按照不确定度贡献由大到小依次是样品中标准品质量浓度、标准曲线、重复性测定、样品称量、样品稀释过程。相对合成标准不确定度为0.0405,相对扩展不确定度为0.081(k=2)。【结论】实验测量中标准品质量分数影响较大,应严格规范标准品溶液稀释的操作,简化稀释步骤,提高测量结果的准确性。

Uncertainty evaluation of total arsenic in pork by inductively coupled plasma mass spectrometry

Objective]To make uncertainty evaluation of total arsenic in pork by using the national food safety standard“GB 5009.11-2014 determination of total arsenic and inorganic arsenic in food”,and discuss the influence of each uncertainty component on the determination results so as to improve the accuracy of the experimental results.Methods]The uncertainty sources that affected the measurement results in the measurement process,including repeatability measurement,sample weighing,sample dilution,standard concentration,standard curve and so on were evaluated.The uncertainty introduced by the repeatability measurement was evaluated by class A,the uncertainty caused by other factors was evaluated by class B,and the phase was calculated according to each component.The synthetic standard uncertainty and the relative expanded uncertainty were discussed,and so were the influence of the uncertainty components on the measurement results.Results]According to the contribution of uncertainty from large to small was the sample standard concentration,standard curve,repeatability determination,sample weighing and sample dilution.The calculated relative composite standard uncertainty was 0.0405,and the relative expanded uncertainty was 0.081(k=2).Conclusion]The experimental results show that the concentration of standard substance has a great influence on the measurement process,so it is necessary to standardize the dilution process and simplify the dilution procedure to improve the accuracy of measurement results.