电感耦合等离子体质谱法测定大豆中硼含量的不确定度评定

目的 通过评定电感耦合等离子体质谱(ICP-MS)法测定大豆中硼含量的不确定度,合理地赋予样品测量值的不确定度,并分析各种因素引入的不确定度分量,从而在实验过程中有针对性地提出改进措施。 方法 采用ICP-MS法测定大豆中硼的含量,结合测定过程建立数学模型,对各影响分量进行不确定度分析,最后得到合成不确定度以及扩展不确定度。 结果 本方法测得样品中硼含量为24.4mg/kg,其扩展不确定度为2.3mg/kg(k=2)。校准曲线拟合、加标回收率、测量重复性、标准系列配制、称样量和消解液定容体积引入的相对标准不确定度分别为3.5%、2.4%、1.7%、0.49%、0.13%和0.06%。 结论 影响ICP-MS法测定大豆中硼含量不确定度的主要因素是校准曲线拟合,加标回收率和测量重复性。消解液定容体积、称样量等影响相对较小。

Uncertainty evaluation for determination of boron in soybean by inductively coupled plasma mass spectrometry

Objective By evaluating the uncertainty of determination of boron content in soybean by inductively coupled plasma mass spectrometry (ICP-MS), the uncertainty of measured value was reasonably assigned to the sample, and the uncertainty component introduced by various factors was analyzed, so as to put forward the improvement measures in the process of experiment. Methods The content of boron in soybean was determined by ICP-MS method. The mathematical model was established in combination with the determination process. The uncertainty of each affected component was analyzed, and the synthetic uncertainty and extended uncertainty were obtained. Results The boron content in the samples was 24.4mg/kg and the extended uncertainty was 2.3mg/kg (k =2). The uncertainty introduced by calibration curve fitting, standard recovery, measurement repeatability, standard series preparation, sample weighing and constant volume of digestion solution are respectively 3.5%, 2.4%, 1.7%, 0.49%, 0.13% and 0.06%. Conclusion The main factors affecting the uncertainty of determination of boron content in soybean by ICP-MS method are calibration curve fitting, standard recovery and repeatability. The effect of constant volume and sample size of digestion solution is relatively small.