离子色谱法测定食品中亚硝酸盐和硝酸盐的不确定度分析

Evaluation of uncertainty in IC determination of nitrate and nitrite in foods

[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 ion chromatography（IC） as uncertainty assessment method for determining the concentration of Nitrate and Nitrite in foods and provide the basis for simplification of assessment method and evaluation of detecting results. [Methods] The calculation formula of the uncertainty was deduced,and factors of uncertainty was analyzed and calculated with uncertainty theory. [Results] The relative expanded uncertainty of NO-2 and NO-3 was 3.815%和3.055%,of which the uncertainty from the pre-treatment were 3.432% and 2.757%,from the concentration of sample solution gained from standard solution and standard curve were 1.665% and 1.313%,and from set volume and weighing sample were 0.076% and 0.029%. [Conclusion] the pre-treatment and the concentration of sample solution were the main sources of uncertainty,and in the future,the uncertainty of similar method could be focused on evaluating the sample pre-treatment and solution concentration.