分光光度法测定白酒中的氰化物含量不确定度的评定

目的评定分光光度法测定白酒中氰化物的不确定度,分析检测条件的改变对检验过程的可靠性及检验结果的准确度的影响。方法在GB 5009.36-2016《食品安全国家标准食品中氰化物的测定》分光光度法的基础上,改为使用20 mL比色管定容溶液体积至12 mL,并确定检测方法不确定度来源,计算各不确定度分量及扩展不确定度。结果当白酒样品中氰化物含量为0.25 mg/L时,扩展不确定度为0.01 mg/L(P=95%, k=2),样品前处理和标准溶液配制对方法不确定度贡献较小,样品重复测定对方法不确定度贡献最大。结论定容体积的改变和使用20mL的比色管对检测过程干扰较弱,对检测结果的准确度影响较小,可以采用提高检测数据稳定性的方法来降低测量不确定度,提高检测结果准确度。

Uncertainty evaluation for the determination of cyanide in liquor by spectrophotometry

Objective To evaluate the uncertainty for the determination of cyanide in liquor by spectrophotometry, and analyze the impact of changes in detection conditions on the reliability of the inspection process and the accuracy of the inspection results. Methods On the basis of the spectrophotometric method according to GB 5009.36-2016 National food safety standard-Determination of cyanide in food, the volume of solution with constant volume of 20 mL colorimetric tube was changed to 12 mL, and the sources of uncertainty of the detection method were determined, and the uncertainty components and extended uncertainty were calculated. Results When the cyanide content in liquor sample was 0.25 mg/L, the extended uncertainty was 0.01 mg/L (P=95%, k=2). The sample pretreatment and standard solution preparation contributed less to the method uncertainty, while the sample repeated determination contributed the most to the method uncertainty. Conclusion The change of constant volume and the use of 20 mL colorimetric tube have a weak interference on the detection process and a small impact on the accuracy of the detection results. Therefore, the method of improving the stability of the detection data can be adopted to reduce the measurement uncertainty and improve the accuracy of the detection results.