能力验证实验水中三氯甲烷测定的不确定度评定

Evaluation on uncertainty in determination of trichloromethane in water by ability validation

目的通过对能力验证实验中三氯甲烷测定的不确定度评定,找出影响检测结果准确性的主要因素,从关键环节加以控制,减少测定过程中的人为和随机误差,确保检测结果准确。方法按国标方法进行测定,建立数学模型,确定不确定度来源并计算各分量,得出合成不确定度,最后形成不确定度报告。结果取k=2(置信概率95%),扩展不确定度为4.8μg/L,结果为(75.7±4.8)μg/L,本次能力验证结果满意(z=1.63,z≤2为满意结果)。结论对本次测定不确定度贡献较大的是标准溶液配制、工作曲线拟合和重复测定这几方面,所以应重点从这几方面加以控制,确保检测结果的准确性。

[Objective]To evaluate the uncertainty in determination of trichloromethane in ability validation experiment, find out the main factors influencing the accuracy of the test results, control the critical points, reduce the artificial and random errors in determination process, and ensure the accuracy of test results. [Methods]The determination was performed according to the national standard method, to establish the mathematical model, determine the uncertainty sources and calculate the uncertainty components, and obtain the synthetic uncertainty, finally form the uncertainty of report. [Results]The expanded uncertainty was 4.8 μg/L and result was （75.7±4.8） μg/L while k=2 （95% confidence probability）. The result of the ability validation was satisfactory （z=1.63, z ≤2 was classified as the satisfactory result）.[Conclusion]The standard solution preparation, working curve fitting and repeated determination make the greatest contribution to the uncertainty for the determination. Therefore, it is important to control these critical points to ensure the accuracy of test results.