石墨炉原子吸收测定大米中的铅不确定度评定

Evaluation of the uncertainty of lead content in rice by graphite furnace atomic absorption spectrometry

评定石墨炉原子吸收光谱法测定大米中铅含量的不确定度,找出影响不确定度的主要因素。按GB 5009.12—2010建立不确定度的数学模型,根据《化学分析中不确定度评估指南》对石墨炉原子吸收光谱法测定大米中铅含量的不确定度进行评定。结果表明:大米铅含量0.100㎎/kg时,其扩展不确定度为0.009 mg/kg(k=2)。石墨炉原子吸收光谱法测定大米铅含量时,样品消解过程和测定样品消解液中铅的质量浓度产生的不确定度对总不确定度影响最大。

The uncertainty of the determination of lead content in rice by graphite furnace atomic absorp- tion spectrometry （ GF - AAS） was evaluated. The main effecting factors on the uncertainty were analyzed. The mathematic model was built according to GB 5009.12 -2010, based on Guide to Evaluation of the Uncertainty in Chemical Analysis. The result showed that when the lead content in rice was O. 100 mg/kg, the expanded uncertainty was 0.009 mg/kg （ k = 2）. When determining the lead content in rice by GF - AAS, the most influential factor on the total uncertainty was the uncertainty produced during sample diges- tion process and determining the mass concentration of lead in sample digestion solution.