微波消解-原子吸收法测定小麦粉中镉的不确定度评定

Evaluation of Uncertainty in Determination of Cadmium in Wheat Flour by Microwave Digestion-Atomic Absorption Spectrometry

[目的]评定微波消解-原子吸收法测定小麦粉中镉的不确定度。[方法]按照《GB 5009.15—2014食品安全国家标准食品中镉的测定》的要求,采用微波消解-原子吸收分光光度法测定小麦粉中镉含量,根据该测量过程建立的数学模型,从样品称量、样品溶液定容、标准溶液的配制、标准曲线的拟合、样品的重复测定、回收率等方面进行不确定度分析计算。[结果]小麦粉样品中的镉含量为0.142mg/kg,扩展不确定度为0.0105mg/kg,k=2。[结论]测量过程中不确定度主要来源于样品消解回收率和标准曲线的拟合。

[Objective]The research aimed to evaluate the uncertainty of determination of cadmium in wheat flour by microwave digestion-atomic absorption spectrometry.[Method]According to the requirements of GB 5009.15-2014 National Food Safety Standard for Determination of Cadmium in Foods,the content of cadmium in wheat flour was determined by microwave digestion-atomic absorption spectrophotometry.According to the mathematical model established by the measurement process,the uncertainty analysis was performed from the aspects of sample weighing,sample solution constant volume,standard solution preparation,standard curve fitting,sample repeat determination and recovery rate.[Result]The cadmium content in the wheat flour sample was 0.142 mg/kg,and the spreading uncertainty was 0.010 5 mg/kg,k=2.[Conclusion]The uncertainty in the measurement process mainly comes from the fitting of the standard curve and the sample digestion recovery rate.