石墨炉原子吸收光谱法测定味精中痕量铅的不确定度评定

以石墨炉原子吸收光谱法测定味精中痕量铅为例,对测定结果的不确定度来源进行分析,对测定过程的主要不确定度分量进行合理评定,包括称量不确定度、体积不确定度、曲线拟合不确定度及测量重复性引入的不确定度。评估了铅含量的合成标准不确定度和扩展不确定度。对于铅含量为0.025×10-6的味精样品,其扩展不确定度为0.002×10-6。

Uncertainty Evaluation of Determination Results for Trace Lead in Monosodium Glutamate by Graphite Furnace Atomic Absorption Spectrometry

The uncertainty measurement of the trace Pb in monosodium glutamate samples by graphite furnace atomic absorption spectrometry(GFAAS) was evaluated in this paper.The results showed that the main sources of the total uncertainty came from the fraction uncertainties of sample weighting,calibration curve fitting,the certified values of standard reference materials,the instrument stability and etc..The total uncertainty for the determination of lead by GFAAS was combined and the expanding uncertainty was calculated with value of 0.002×10-6 for the monosodium glutamate sample with lead content of 0.025×10-6.