原子吸收法测定大米粉中镉的不确定度评定

Evaluation of Uncertainty in Determination of Cadmium in Rice Flour by Atomic Absorption Method

目的采用无火焰原子吸收法对大米粉中的镉进行测定。方法分析测量不确定的主要来源,在整个分析测定过程:称量、容量器具的体积、标准物质、直线回归方程、重复性测定和仪器示值误差等是不确定度的主要来源。结果按照JJF 1059.1-2012《测量不确定度评定与表示》的规定进行评定,舍弃贡献小,可以忽略不计的不确定度分量,最终计算给出扩展不确定度为:K=2,U=48μg/kg,C_(Cd)=(300.01±48.00)μg/kg。结论该结果更加客观和接近真值,降低了检测机构的检测风险。

Objective To determine the cadmium in rice flour by flame atomic absorption spectrometry.Methods Analyze the main sources of measurement uncertainty.Throughout the analysis and measurement process：weighing,volume of volumetric instruments,reference materials,linear regression equations,repeatability measurements and instrumental indication errors are the main sources of uncertainty.Results According to JJF 1059.1-2012 ＂Measurement Uncertainty Evaluation and Representation＂,the contribution is small, the negligible uncertainty component is discarded,and the final calculation gives the extended uncertainty as：K=2,U=48 μg/kg,CCd=（300.01±48.00）μg/kg. Conclusion The result is more objective and close to the true value,which reduces the detection risk of the testing organization.