“双人八平行”实验中A类不确定度评定的初探——以化学需氧量测定中硫代硫酸钠的标定为例

A Preliminary Study on the Evaluation of Type A Uncertainty in the “Double Eight Parallel”Experiment——Case Study of Sodium Thiosulphate Calibration in Chemical Oxygen Demand Determination

环境监测中标准溶液的标定一般采用"双人八平行"来测定,取其平均值作为标定值。"双人八平行"即包含了重复性测量条件,同时又包含了复现性测量条件,由于操作人员的操作手法、熟练程度、读数估值习惯不同,两组数据一定存在一个组间变动性偏差,但"双人八平行"的不确定度分析几乎查不到相关资料,大部分人用贝塞尔公式法进行计算。在分析时一定既要分析重复性偏差,同时又要分析组间变动性偏差,才能全面反映"双人八平行"检测的不确定度。用一个实例来全面分析"双人八平行"A类不确定度的评定。

Calibration of standard solution generally use ＂double eight parallel＂ in the environmental monitoring, the average value is used as the calibration value. ＂Double eight parallel＂ contains not only the repetition measurement condition, but also the reproducibility condition. Due to different operating skill, experience, and reading accuracy of the operators, the variable deviation must exist between two groups of data. The analysis of the uncertainty of ＂ double eight parallel＂ has not been reported yet, it was calculated by Bessel formula mostly. In the analysis, the repeatability deviation as well as the deviation between the two groups should be both analyzed to reflect the uncertainty of the ＂double eight parallel＂ comprehensively. In this paper, a case study was taken to analyze the evaluation of the type A uncertainty in the ＂double eight parallel＂.