2021年尿碘外质控考核结果的不确定度评定

Uncertainty evaluation of the external quality control examination of urinary iodine in 2021

目的评定尿碘外质控考核结果的不确定度。方法采集国家碘缺乏病参照实验室于2021年发放的冻干人尿考核样品2份,武汉市疾病预防控制中心公共检验检测中心根据《尿中碘的测定第1部分:砷铈催化分光光度法》(WS/T 107.1-2016)的操作步骤检测尿碘,识别不确定度的来源,量化不确定度,并合成总不确定度。结果2份考核样品中尿碘浓度检测结果分别为(64.6±4.7)、(227±16)μg/L,考核合格,其中用移液枪移取标准品、样品和试剂溶液,加标回收实验及拟合标准曲线是不确定度的主要来源,其变量为5%~36%。结论选用精度高的玻璃器皿和检定合格的移液枪,增加测定标准系列和样品的测定次数,可提高操作水平,保证标准曲线较好的相关性和回收率的精确度,达到降低不确定度的影响,提高检测结果准确度的目的。

Objective To evaluate the uncertainty of the assessment results of external quality control of urinary iodine.Methods Public Inspection and Testing Center,Wuhan Center for Disease Control and Prevention collected two assessment samples distributed by the National Iodine Deficiency Disorders Reference Laboratory in 2021,according to the operating steps of"Determination of Iodine in Urine-Part 1:As 3+-Ce 4+Catalytic Spectrophotometry"(WS/T 107.1-2016),examinated urinary iodine,identified the source of uncertainty,quantified the uncertainty,and ultimately synthesized the uncertainty.Results The results of urinary iodine concentration detection in two assessment samples were(64.6±4.7)μg/L and(227±16)μg/L,respectively,passing the assessment,among which using a pipette to absorb the standard,sample,and reagent solution,adding standard recovery experiments,and fitting standard curves were the main sources of uncertainty,which of variables ranged from 5%to 36%.Conclusion Selecting high-precision glassware and qualified pipettes,increasing the number of measurements of standard series and samples,can improve the operational level,ensure good correlation of standard curves and accuracy of recovery rates,reduce the impact of uncertainty,and improve the accuracy of detection results.