分光光度法测定水中亚硝酸盐含量的不确定度评定

Evaluation on Uncertainty Measurement of Measuring the Nitrite Content in Water by Spectrophotometer

评定分光光度法测定水中亚硝酸盐含量的不确定度。采用紫外分光光度法测定水中亚硝酸盐的含量,运用测量不确定度的基本方法和程序,分析影响结果不确定度的各种因素,建立数学模型,合成计算亚硝酸盐含量的不确定度。通过分析计算标准溶液的纯度、标准储备液配置、标准溶液稀释过程、曲线拟合过程、待测样品稀释、样品测定重复性等带来的不确定度分量,最后合成水中亚硝酸盐的含量的不确定度为0.485 mg/L,测量扩展不确定度:0.017 mg/L(K=2)。

Spectrophotometry was used to determine the uncertainty of nitrite contents in water. Ultraviolet spectrophotometry was adopted to determine the nitrite contents in water. Basic method and procedure measuring uncertainty were also used to analyze various factors influencing the results. Mathematical model was established to calculate the uncertainty of nitrite contents. By analyzing and calculating the uncertainty components generated by purity of standard solution, standard stock solution allocation, dilution process of standard solution, curve fitting process, dilution of unknown samples and sample measurement repeatability, it was found that the uncertainty of nitrite contents in water was 0.485 mg/L and the uncertainty in measurement reached 0.017 mg/L（K=2）.