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目的用氢化物发生-原子荧光法对奶粉样品中总砷含量的测量不确定度进行分析,找出影响不确定度因素,对测量不确定度进行计算和评定。方法通过AFS-230E原子荧光法对婴幼儿配方奶粉样品中总砷的测定,分析了测量过程中的工作曲线、标准溶液、测量重复性和仪器性能等产生不确定度的来源,并量化不确定度各分量,计算合成标准不确定度。结果本次检测线性方程为A=31.76C+118.46,相关系数r=0.9993。测得配方奶粉样品中总砷的含量为0.026mg/kg,扩展不确定度为U95=0.020mg/kg(k=2)。结论影响本方法不确定度的主要因素是校准曲线的回归和测量的重复性。
OBJECTIVE: To analyze the uncertainty of measurement of total arsenic in milk powder by hydride generation-atomic fluorescence spectrometry, find out the factors affecting the uncertainty, and calculate and evaluate the measurement uncertainty. Methods The determination of total arsenic in infant formula milk powder samples by AFS-230E atomic fluorescence spectrometry was used to analyze sources of uncertainty such as working curve, standard solution, measurement repeatability and instrument performance during measurement, and the uncertainty of quantification was uncertain Degrees of each component, calculate the composite standard uncertainty. Results The test linear equation was A = 31.76C + 118.46, correlation coefficient r = 0.9993. The total arsenic content in the formula was measured as 0.026 mg / kg with an expanded uncertainty of U95 = 0.020 mg / kg (k = 2). Conclusion The main factors affecting the uncertainty of this method are the regression of the calibration curve and the repeatability of the measurement.