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[目的]建立离子色谱法测定食品中NO2-和NO3-的不确定度评定方法,给出不确定度,为简化评定方法和提高检测质量提供依据。[方法]应用测量不确定度理论,建立检测方法的数学模型,找出影响不确定度的因素并对各个不确定度分量进行评估。[结果]食品中NO2-和NO3-的相对扩展不确定度为3.815%和3.055%,其中样品前处理引入的不确定度分为3.432%、2.757%;求样品溶液中NO2-和NO3-浓度产生的不确定度为1.665%、1.313%,而样品定容体积和称量引入的不确定度为0.076%和0.029%。[结论]样品前处理和样品溶液中NO2-和NO3-浓度为不确定度的主要来源。今后在类似方法的不确定度评定中,可把重点放在前处理和样品溶液浓度计算引入的不确定度评定上。
[Objective] To establish a method for the determination of the uncertainty of NO2- and NO3- in food by ion chromatography, give the uncertainty and provide the basis for simplifying the assessment method and improving the quality of detection. [Method] Applying the theory of measurement uncertainty, establishing the mathematical model of detection method, finding the factors that affect the uncertainty and evaluating the components of each uncertainty. [Result] The relative uncertainty of expansion of NO2- and NO3- in food was 3.815% and 3.055% respectively. The uncertainty introduced by sample pretreatment was 3.432% and 2.757% respectively. The NO2- and NO3- concentrations in the sample solution The resulting uncertainty was 1.665% and 1.313%, respectively, while the uncertainty of the sample volumetric volumetric and weighed measurements was 0.076% and 0.029%. [Conclusion] The concentrations of NO2- and NO3- in sample pretreatment and sample solution are the main sources of uncertainty. In the future assessment of the uncertainty of similar methods, emphasis may be placed on the assessment of the uncertainty introduced by pretreatment and calculation of sample solution concentration.