抑制电导离子色谱法测定蔬菜中硝酸盐的不确定度评定

Uncertainty evaluation of nitrate determination in vegetables by ion chromatography with suppressed conductivity detector

硝酸盐是蔬菜中主要的无机酸盐之一,人体内大部分的硝酸盐通过食用蔬菜摄入,但硝酸盐摄入量过高会危害人体健康。本文依据GB 5009.33-2010《食品中亚硝酸盐与硝酸盐的测定》和JJF1059.1-2012《测量不确定度评定与表示》,对抑制电导离子色谱法测定蔬菜中硝酸盐的不确定度进行了评定。对测定过程产生的不确定分量进行了分类讨论,通过各分量相对标准不确定度,计算出合成标准不确定度和扩展不确定度。通过分析评估发现,测定不确定度的主要影响因素依次是前处理方法回收率、标准溶液及配制、样品制备均匀性,产生影响较小的不确定度分量是样品的称量和试液的定容,相对扩展不确定度为6.8%。

Nitrate is one of the main inorganic acid substances in vegetables,and people get most nitrate by eating vegetables,but it is bad for getting too much nitrate into human body. According to GB 5009.33-2010（Determinatio n of nitrite and nitrate in foods）and JJF1059.1-2012（Evaluation and Expression of Uncertainty in Measurement）,The Uncertainty Evaluation of Nitrate Determination in vegetables by ion Chromatography with Suppressed Conductivity Detector was discussed in this paper. The components of uncertainty in the detection process were classified and discussed,and the relative combined standard uncertainty and expanded uncertainty were also evaluated finally. According to the analysis,the main influencing factors of the uncertainty of Nitrate Determination in vegetables are the Rate of pretreatment recovery,the preparation of standard solution,the uniformity of prepared samples. The least influencing factors are sample weight and volume change, the relative expanded uncertainty is 6.8%.