石墨炉原子吸收法测定大米中镉含量不确定度的评定

Evaluation of Uncertainty in Determination of Cadmium in Rice by Graphite Furnace Atomic Absorption Spectrometry

[目的]分析石墨炉原子吸收法测定大米中镉含量的不确定度来源。[方法]依据JF1059.1—2012《测量不确定度评定与表示》,建立石墨炉法测定大米中镉含量不确定度的数学模型,对测量过程中的各不确定度来源进行分析、量化和合成。[结果]石墨炉原子吸收法测定大米中镉元素浓度的不确定度主要来源于重复性试验、定容体积、标准物质、试样质量,以及最小二乘法拟合标准曲线得出试样液中镉的浓度时产生的不确定度。其中重复性试验导致的不确定度相对较大,因此在试验过程中需要加强重复试验技术。[结论]该研究为更加精准地检测大米中的镉含量提供了依据。

[Objective]The aim of this study was to analyze the uncertainty sources of cadmium content in rice by graphite furnace atomic absorption spectrometry(GFAAS).[Method]According to Evaluation and Expression of Uncertainty in Measurement(JF1059.1—2012),the mathematical model of uncertainty in the determination of cadmium content in rice by GFAAS was established,and the sources of uncertainty in the measurement process were analyzed,quantified and synthesized.[Result]The uncertainty in the determination of cadmium concen-tration in rice by GFAAS mainly came from the repeatability test,constant volume,standard material,sample mass,and the uncertainty generated by fitting the standard curve with the least square method to obtain the cadmium concentration in the sample solution.The uncertainty caused by repetitive test was relatively large,so repetitive test technology needed to be strengthened in the test process.[Conclusion]This study provided a basis for more accurate detection of cadmium content in rice.