分光光度法测定水质中亚硝酸盐氮浓度的不确定度分析研究

检测工作不确定度评定能力是实验室认可的一项基本要求。本文根据吸光度与待测试份中亚硝酸盐氮与相关物质反应生成的红色染料含量（浓度）成正比关系可以测定水质中亚硝酸盐氮含量的原理，使用分光光度法对水质中亚硝酸盐氮浓度进行测定，通过分析线性回归方程不确定度的产生原因、标准贮备液稀释成标准溶液后配制成不同浓度的标液系列所产生的测量不确定度、平行试验数据重复性引起及该方法使用过程可能产生的各种不确定度，建立相关数学模式，来计算分光光度法测定水质中亚硝酸盐氮浓度的标准不确定度及其扩展不确定度。

Uncertainty Analysis on Nitrite Nitrogen Concentration in Water by Spectrophotometry

The evaluation on detection uncertainty is a basic requirement of laboratory accreditation. This study measured the nitrite nitrogen content in water by spectrophotometry based on the principle that the absorbance and the content （concentration） of the red dye produced by nitrite nitrogen in the sample are proportional. Then, this paper analyzed the causes of uncertainty a- bout the linear regression equation, the standard stock solution diluted into a standard solution preparation of standard solution of different concentrations, parallel test data repeatability, and various possible methods. In the end, the standard uncertainty and the expanded uncertainty of nitrite nitrogen concentration are calculated by mathematical model. Key words： nitrite nitrogen; un- certainty; spectrophotometry; expanded uncertainty.