电感耦合等离子体发射光谱法测量土壤中有效锌含量的不确定度评估

Evaluation of measurement uncertainty in determining available zinc in soil by inductively coupled plasma optical emission spectrometry

对电感耦合等离子体发射光谱法(ICP-OES)测定土壤有效锌含量的不确定度进行评定,分析了整个检测过程产生不确定度的来源,对称样量、浸提液体积、标准系列溶液配制、线性标准曲线拟合、测量重复性等产生的不确定度分量进行计算,量化给出扩展不确定度。待测土壤中有效锌含量最终结果表示:w(Zn)=(1.12±0.10)mg/kg,包含因子k=2,置信概率为95%。测量过程中,标准溶液制备所产生的不确定度最大。因此,在ICP-OES法测定土壤样品有效锌时应足够重视标准溶液制备与曲线拟合过程,以减小测量不确定度。本文研究结果为控制ICP-OES法测定土壤有效锌数据质量提供了理论依据。

Available zinc（ Zn） in soil is widely extracted by DTPA（ diethylenetriaminepentaacetic acid） solution. Zn concentration in the extract is increasingly determined by ICP-OES（ inductively coupled plasma optical emission spectrometry）technique. The uncertainty in measurement of soil available Zn by ICP-OES method was evaluated. The sources of uncertainty in the testing process including sample weight,extract volume,Zn standard solution series preparation,linear standard curve fitting and measurement repeat were quantified dividedly. The expand uncertainty was calculated and the results of soil available Zn determined by ICP-OES method was then conveniently expressed as w（ Zn） =（ 1. 12 ± 0. 10） mg/kg,a coverage factor k = 2. A confidence interval of 0. 10 mg/kg at probability 95% level was suggested for the measurement of soil available Zn by ICP-OES. The greatest uncertainty of measurement might result from Zn standard solution series curve preparation. It suggested more attention should be paid on the preparation process of Zn standard solution and curve fitting to reduce the measurement uncertainty in the determination of soil available Zn by ICP-OES.