石墨炉-原子吸收光谱法测定大米中镉的不确定度评定

目的评定石墨炉-原子吸收光谱法(graphite furnace atomic absorption spectrometry, GFAAS)测定大米中镉含量的测量不确定度。方法依据CNAS-GL06《化学分析中不确定度的评估指南》、JJF 1059.1-2012《测量不确定度评定与表示》规定的基本程序,通过建立数学模型,分析确定不确定度来源,计算得到测量结果的合成标准不确定度和扩展不确定度。结果以石墨炉-原子吸收法测定大米中镉含量,其不确定度主要来源为标准曲线拟合,其次为测量重复性,Cd含量为(0.19±0.01)mg/kg,k=2。结论本方法客观可靠,可以分析GFAAS检测大米中镉的不确定来源和其影响程度,为降低不确定度,提高检测准确度有重要意义。

Uncertainty evaluation of determination of cadmium in rice by graphite furnace atomic absorption spectrometry

Objective To evaluate the uncertainty of determination of cadmium content in rice by graphite furnace atomic absorption spectrometry (GFAAS). Methods According to the basic procedures specified in CNAS-GL06 Guidelines for the evaluation of uncertainty in chemical analysis and JJF 1059.1-2012 Measurement and expression of measurement uncertainty, the mathematical model was established to analyze and determine the source of uncertainty, and the synthetic standard uncertainty and extended uncertainty of the measurement results were calculated. Results The uncertainty determination of cadmium in rice by GFAAS was mainly from the standard curve fitting, followed by the measurement repeatability. The concentration of Cd was (0.19±0.01) mg/kg, k=2. Conclusion The method is objective and reliable, and can analyze the uncertain source of cadmium in rice by GFAAS and its influence degree, which is important for reducing the uncertainty and improving the detection accuracy.