石墨炉原子吸收光谱法测定大米中镉含量的不确定度评定

摘要

依据GB 5009.15-2003用石墨炉原子吸收光谱法测定大米中的镉含量,分析测定结果的影响因素,归纳出测量不确定度的主要来源:标准工作曲线及方法回收率等,形成不确定度评定程序和方法,经量化和合成得到相对标准不确定度,从而求得扩展不确定度.当镉含量为0.098 mg／kg时,相对标准不确定度为0.041 7,扩展不确定度为0.008 2 mg／kg(k=2).%Factors affecting the determination of cadmium content in rice by the method of GB 5009.15-2003 Determination of Cadmium in Foods were analyzed,the main sources of measurement uncertainty were summarized which consist of the standard working curve and the recovery of the method and so on.A procedure and a method for uncertainty evaluation was established,and a relative standard uncertainty was obtained after calculating and synthesizing various uncertainty components and then the expanded uncertainty was obtained.The content of cadmium in rice was determined to be 0.098 mg/kg,the relative standard uncertainty for the determination was 0.041 7,and the expanded uncertainty was 0.008 2mg/kg (k=2).