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目的对微量分光光度法测定饮用水中硫酸盐含量的不确定度进行评定。方法依据JJF1059.1-2012《测量不确定度评定与表示》建立数学模型,分析和识别不确定度来源,运用不确定度传播律对饮用水中硫酸盐的微量分光光度法进行不确定度评定。结果用微量分光光度法测定饮用水中硫酸盐含量,测量结果为49.5mg/L,合成标准不确定度为0.95mg/L。取包含因子k=2,置信水平约为95%,扩展不确定度为1.9mg/L。结论线性回归产生的不确定度分量最大,其次是标准系列溶液的配制过程,取样体积带来的不确定度分量最小。实际工作中,提高校准曲线线性相关性和避免使用较小容量器皿配制标准系列溶液,可大幅减小测量结果的不确定度。
Objective To assess the uncertainty of trace sulfate spectrophotometry in drinking water. Methods Based on JJF1059.1-2012 “Evaluation and Expression of Uncertainty in Measurement”, a mathematical model was established to analyze and identify the sources of uncertainty. Uncertainty propagation method was used to assess the uncertainty of trace sulfates in drinking water . Results The content of sulfate in drinking water was determined by micro-spectrophotometry. The measured result was 49.5 mg / L and the standard uncertainty of synthesis was 0.95 mg / L. Take the inclusion factor k = 2, the confidence level is about 95%, and the extended uncertainty is 1.9mg / L. Conclusion Linear regression has the highest uncertainty components, followed by the standard series of solutions. The sampling volume brings the smallest uncertainty component. In practice, increasing the linearity of the calibration curve and avoiding the use of smaller volumetric vessels to formulate standard series solutions can significantly reduce the uncertainty of the measurement results.