氢化物原子荧光法测定大米中总砷含量的不确定度评定

Uncertainty evaluation for the determination of total arsenic content in rice by hydride atomic fluorescence method

中文关键词:  大米  总砷  氢化物原子荧光法  不确定度

英文关键词:rice  total arsenic  hydride atomic fluorescence method  uncertainty

中文摘要:

      目的 评定氢化物原子荧光法测定大米中总砷含量的不确定度。方法 依据JJF 1059.1—2012《测量不确定度的评定与表示》和CNAS—GL006: 2019《化学分析中不确定度的评估指南》, 样品经硝酸-高氯酸-硫酸消解, 硫脲-抗坏血酸还原测定总砷含量。同时分析检测过程中的不确定度来源, 计算相对标准合成不确定度, 最终得到大米中总砷的扩展不确定度。结果 当大米中总砷含量为0.144 mg/kg时, 在95%的置信区间下, 扩展不确定度为0.012 mg/kg(k=2)。结论 采用氢化物原子荧光法测定时, 不确定度的主要来源为样品消解、标准溶液的配制及测量重复性所产生的不确定度。

英文摘要:

      Objective To evaluate the uncertainty for determination of total arsenic content in rice by hydride atomic fluorescence method. Methods According to JJF 1059.1—2012 Measurement uncertainty evaluation and expression and CNAS—GL 006: 2019 Evaluation guide for uncertainty in chemical analysis, the sample was digested by nitric acid-perchloric acid-sulfuric acid, reduced by thiourea-ascorbic acid, and then determined the total arsenic content. The uncertainty source in the detection process was analyzed, the relative standard synthetic uncertainty was calculated, and finally the expanded uncertainty of total arsenic in rice was obtained. Results When the total arsenic content in rice was 0.144 mg/kg, and the expanded uncertainty was 0.012 mg/kg (k=2) at the 95% confidence interval. Conclusion The uncertainty measured by hydride atomic fluorescence method mainly comes from sample digestion, standard solution preparation and measurement repeatability.