微波消解-石墨炉原子吸收光谱法测定大米中铅含量的不确定度评定

Evaluation of Measurement Uncertainty of Lead in Rice by Microwave Digestion-Graphite Furnace Atomic Absorption Spectrometry

铅是大米重金属残留的主要污染物之一,其含量是衡量大米污染情况的重要指标。按GB 5009.12—2017《食品安全国家标准食品中铅的测定》中的第一法石墨炉原子吸收光谱法测定铅含量,建立不确定度的数学模型,根据JJF 1059.1—2012《测量不确定度评定与表示》对实验中的各项影响因素进行评定,确定微波消解-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。结果表明:大米铅含量为0.104 mg/kg时,其扩展不确定度为0.0166 mg/kg(k=2)。微波消解-石墨炉原子实收光谱法测定大米铅含量时,标准曲线拟合引入的不确定度最大,其次为样品的重复性测定和配置铅标准溶液引入的不确定度,其他影响较小。

Lead is one of the main heavy metal residues pollutants in rice,the content is one of the most important indexes of rice pollution.According to GB 5009.12—2017<The national food safety standards determination of lead in food>determinate the content of lead with the first method of graphite furnace atomic absorption spectrometry,establish the mathematical model of uncertainty,assess the experiment based on JJF 1059.1—2012 Evaluation and identification of uncertainty in measurement.Use microwave Digestion Graphite furnace atomic absorption spectrometry to determinate the uncertainty of lead content in rice,and find out the influence of uncertainty factors.The results showed that the Pb content of rice was 0.104 mg/kg,the expanded uncertainty was 0.0166 mg/kg(k=2).When used microwave Digestion Graphite Furnace Atomic Spectrometry to determinate the lead content in rice,the uncertainty of standard curve was the largest,followed by the uncertainty of repeated sample determination and configuration of lead standard solution,other less affected.