使用控制图法对原子荧光法测定土壤中砷进行不确定度评定

Uncertainty Evaluation of the Atomic Fluorescence Spectrometry Measuring Arsenic in Soil by the Control Chart Method

根据《检测实验室中常用不确定度评定方法与表示》(GB/T 27411-2012)中控制图法,在期间精密度测量条件下按照《土壤和沉积物汞、砷、硒、铋、锑的测定微波消解/原子荧光法》(HJ 680-2013)对土壤中砷进行重复测量,得到34组测量数据。首先计算其正态统计量(A^(2*)),并判断数据的正态性、独立性和分辨力适宜性;其次再绘制控制图,使用失控准则判断测量系统处于受控状态;最后使用t检验判断数据统计上的偏倚受控。三者均满足的情况下,可视期间精密度标准偏差为实验室土壤中砷的测量不确定度。

According to the control chart method in R outine methods for evpluation and expression of measure-ment uncertainty in testing laboratory(GB/T 27411-2012),under the condition of period precision measurement,this paper repeatedly measures arsenic in soil according to Soil and sedimen-Determination of mercury,arsenic,selenium,bismuth,antimony-Microwave dissolution/Atomic fluorescence spectrometry(HJ680-2013),and ob-tains 34 sets of measurement data.This paper firstly calculates its normality statistics(A^(2*))and judges the normality,independence and resolution suitability of the data,then it draws a control chart and uses the out-of-control crite-rion to judge that the measurement system is under control,and it finally uses t-tests to judge the control for the statistical bias of the data.When all three are met,the period precision standard deviation can be regarded as the measurement uncertainty of arsenic in soil in the laboratory.