微波消解电感耦合等离子体质谱法测定大米样品中铅含量的不确定度评估

Uncertainty evaluation for determination of lead content in rice by microwave digestion-inductively coupled plasma mass spectrometry

中文关键词:  电感耦合等离子体质谱法  微波消解  不确定度  铅  大米

英文关键词:inductively coupled plasma mass spectrometry  microwave digestion  uncertainty evaluation  lead  rice

中文摘要:

      目的 建立微波消解-电感耦合等离子体质谱法(microwave digestion -Inductively coupled plasma mass spectrometry)测定大米样品中的铅含量不确定度模型。方法 按照CNAS-GL 006:2018的评估方法, 建立结果不确定度评估数学模型, 量化不确定度分量, 计算扩展不确定度。结果 经评定, 大米样品中铅的测定结果为限量值附近(0.20 mg/kg)时, 扩展不确定度为0.020 mg/kg (k=2)。结论 影响铅测定不确定度的主要因素是样品中铅浓度测定时的标准溶液稀释过程, 其次是重复性试验和回收试验, 样品称量和溶液定容可忽略不计。

英文摘要:

      Objective To establish the uncertainty model of determination of lead in rice by microwave digestion-inductively coupled plasma mass spectrometry. Methods According to the CNAS-GL006:2018, a mathematical model for uncertainty evaluation was established. The component of uncertainty was quantified, and the expanded uncertainty was calculated. Results The expanded uncertainties of the methods was 0.020 mg/kg (k =2), when the determination results of lead in rice were closed to the maximum allowable limit (0.20 mg/kg). Conclusion The principal factors of contribution to uncertainty of lead determation were standard solution dilution process in the determination of lead concentration in samples, while the repeatability and recovery rate were only a minor factor. The influence of sampling amount and solution constant volume could be neglected.