石墨炉原子吸收光谱法测定食用植物油中铅含量的不确定度评定

Uncertainty Evaluation of Lead in Edible Vegetable Oil byGraphite Furnace Atomic Absorption Spectrometry

目的:对石墨炉原子吸收光谱法测定食用植物油中铅的不确定度进行评定。方法:根据测定过程,建立数学模型,对由测量重复性、样品称量、试样定容、标准溶液配制、标准曲线拟合、样品回收率等方面引入的测量不确定度进行计算。结果:食用植物油样品铅含量为0.042 76 mg·kg^(-1),扩展不确定度为0.008 24 mg·kg^(-1)(k=2),测量结果可表示为(0.042 76±0.008 24)mg·kg^(-1)。结论:测量过程中校准曲线的拟合引起的不确定度影响最大,评定得到的不确定度可以定量反映测定结果的准确度,从而更好地指导实验室的内部质量控制。

Objective:To evaluate the uncertainty of determination of lead in edible vegetable oil by graphite furnace atomic absorption spectrometry.Method:According to the measurement process,a mathematical model was established to calculate the uncertainty of measurement from the aspects of measurement repeatability,sample weighing,sample volume,standard solution preparation,standard curvefitting and sample recovery,etc.Result:The lead content of edible vegetable oil sample was 0.04276 mg·kg^(-1),-1 the extended uncertainty was 0.00824 mg·kg(k=2),and the measured result could be expressed as(0.04276±0.00824)mg·kg^(-1).Conclusion:In the measurement process,the uncertainty caused by the standard curvefitting has the greatest influence.The uncertainty obtained from the evaluation can reflect the accuracy of the measurement results quantitatively,so as to better guide the internal quality control of the laboratory.