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采用电感耦合等离子体质谱法(ICP-MS)测定谷物中的重金属元素砷(As)、镉(Cd),分析测定过程,确定不确定度来源,建立不确定度评定数学模型。对单个不确定度分量进行合成和扩展,建立ICP-MS测定谷物中As、Cd的不确定度评定方法。结果表明:As含量=(0.33±0.026)mg/kg,K=2;Cd含量=(0.16±0.016)mg/kg,K=2。本方法测定不确定度的主要来源为4个方面,按引入的不确定度分量贡献大小排序依次为溶液测定、测量重复性、样品定容、称样量。
The determination of heavy metals arsenic (As) and cadmium (Cd) in grain by inductively coupled plasma mass spectrometry (ICP-MS), the analysis of the determination process, and the determination of the source of uncertainty, the establishment of a mathematical model for the evaluation of uncertainty. A single uncertainty component was synthesized and extended to establish the method for the determination of the uncertainty of As and Cd in grain by ICP-MS. The results showed that As content was (0.33 ± 0.026) mg / kg and K = 2, Cd content was (0.16 ± 0.016) mg / kg and K was 2. The main sources of the uncertainty of the method for the determination of four aspects, according to the introduction of the contribution of uncertainty component order followed by solution determination, measurement repeatability, sample volume, sample size.