分光光度法测定白菜中亚硝酸盐的不确定度评定

Evaluation of Uncertainty in Spectrophotometric Determination of Nitrite in Chinese Cabbage

通过对分光光度法测白菜中亚硝酸盐的含量测定过程的研究,确定测定结果的不确定度。建立不确定度的数学模型,对各不确定度分量进行合成和扩展,最终建立白菜中亚硝酸盐含量的不确定度评定方法。影响测量结果不确定度的因素共有4项,按其影响大小顺序排列分别为测量重复性、标准曲线法测定样液中亚硝酸酸盐质量、溶液定容以及试样称量。其不确定度报告为白菜中亚硝酸盐含量(12.3±1.08)mg/kg,包含因子k=2。

The sources of uncertainty in the spectrophotometric determination of nitrite in Chinese cabbage were investigated by analyzing whole determination procedure. Each uncertainty component was modeled, synthesized and developed a method for the evaluation of uncertainty in spectrophotometric determination of nitrite in Chinese cabbage. The uncertainty was attributed to four sources. The order of their impacts was measurement repeatability, nitrite mass determined by standard curve, sample dilution and sample weighting. The results of uncertainty evaluation showed the nitrite content to be （12.3±1.08） mg/kg （k = 2）.