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    X射线荧光光谱法测定新研制土壤标准物质中11种元素的含量

    Determination of 11 Elements in Newly Developed Soil Reference Materials by X-Ray Fluorescence Spectrometry

    • 摘要: 用粉末压样机将5.0 g经105℃烘干的样品制成样片,采用X射线荧光光谱法(XRF)测定其中铅、砷、铜、锌、铬、镍、钴、钒、锰、锡和钼等11种元素的含量。以经验系数法和康普顿散射内标法校正基体效应和谱线重叠干扰,选择65种土壤、沉积物及岩石国家标准物质用于绘制校准曲线。结果显示,11种元素的质量分数在一定范围内与其对应的荧光强度呈线性关系,检出限(3s)为1.0~3.9 μg·g-1,测定值的相对标准偏差(n=10)为0.64%~9.2%。对新研制的30个农用地土壤成分标准物质进行测定,按照HJ 780-2015的质量控制标准评估各元素的测定准确度,结果表明:铅、铜、锌、铬、镍、钒、锰的测定合格率均为100%,说明XRF可用于土壤中这7种元素的测定;钴的测定合格率为93.3%,这是由于样品中高含量铁的影响;砷的测定合格率为80.0%,当砷的质量分数小于13 μg·g-1时准确度较差;锡、钼的测定合格率不足50.0%,因此不建议用XRF测定土壤中锡和钼的含量。

       

      Abstract: 5.0 g of the sample dried at 105℃ was treated by powder tablet machine, and 11 elements, including Pb, As, Cu, Zn, Cr, Ni, Co, V, Mn, Sn and Mo, were determined by X-ray fluorescence spectrometry (XRF). The matrix effect and spectral overlapping interference were corrected by empirical coefficient method and Compton scattered internal standard method. The 65 national reference materials of soil, sediment and rock were selected to fit the calibration curves. It was shown that linear relationships between values of mass fraction of 11 elements and their fluorescence intensities were kept in the definite ranges, with detection limits (3s) in the range of 1.0-3.9 μg·g-1, and RSDs (n=10) of the determined values were in the range of 0.64%-9.2%. The 30 newly developed reference materials for soil composition of agricultural land were determined, and accuracy of each element was evaluated according to the quality control standard of HJ 780-2015. It was shown that the determined pass rates of Pb, Cu, Zn, Cr, Ni, V and Mn were 100%, indicating that XRF could be used for the determination of those 7 elements in soil. The determined pass rate of Co was 93.3%, which was due to the influence of high content of Fe in the sample. The determined pass rate of As was 80.0%, and accuracy was poor when the mass fraction of As was below 13 μg·g-1. The determined pass rates of Sn and Mo were less than 50.0%, so XRF was not recommended for the determination of Sn and Mo in soil.

       

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