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目的建立石墨炉原子吸收光谱法测定面粉中镉不确定度的方法。方法以GB/T5009.15-2003石墨炉原子吸收光谱法测定面粉中镉含量为例,根据JJF 1059-1999技术规范要求,分析该测定水平下镉含量测定结果的不确定度。结果石墨炉原子吸收光谱法测定2份面粉中镉的含量,结果分别为(176±9)μg/kg(k=2)、(366±22)μg/kg(k=2)。结论用石墨炉原子吸收光谱法测定面粉中镉含量的过程中,由拟合直线求样品溶液浓度、测量重复性以及消化回收率带来的不确定度是该方法不确定度的主要来源。
Objective To establish a method for determining the uncertainty of Cd in flour by graphite furnace atomic absorption spectrometry. Methods The determination of cadmium content in flour by graphite furnace atomic absorption spectrometry (GB / T5009.15-2003) was taken as an example. According to the technical specifications of JJF 1059-1999, the uncertainty of determination result of cadmium content was analyzed. Results The contents of cadmium in two flour samples were determined by graphite furnace atomic absorption spectrometry and the results were (176 ± 9) μg / kg (k = 2) and (366 ± 22) μg / kg (k = 2), respectively. Conclusion The determination of Cd concentration in flour by graphite furnace atomic absorption spectrometry is the main source of the uncertainty of the proposed method. The concentration of sample, the repeatability of measurement and the uncertainty of digestion recovery are obtained by fitting straight lines.