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陈静, 高志军, 陈冲科, 刘延霞, 张明炜. X射线荧光光谱法分析地质样品的应用技巧[J]. 岩矿测试, 2015, 34(1): 91-98. DOI: 10.15898/j.cnki.11-2131/td.2015.01.012
引用本文: 陈静, 高志军, 陈冲科, 刘延霞, 张明炜. X射线荧光光谱法分析地质样品的应用技巧[J]. 岩矿测试, 2015, 34(1): 91-98. DOI: 10.15898/j.cnki.11-2131/td.2015.01.012
Jing CHEN, Zhi-jun GAO, Chong-ke CHEN, Yan-xia LIU, Ming-wei ZHANG. Application Skills on Determination of Geological Sample by X-ray Fluorescence Spectrometry[J]. Rock and Mineral Analysis, 2015, 34(1): 91-98. DOI: 10.15898/j.cnki.11-2131/td.2015.01.012
Citation: Jing CHEN, Zhi-jun GAO, Chong-ke CHEN, Yan-xia LIU, Ming-wei ZHANG. Application Skills on Determination of Geological Sample by X-ray Fluorescence Spectrometry[J]. Rock and Mineral Analysis, 2015, 34(1): 91-98. DOI: 10.15898/j.cnki.11-2131/td.2015.01.012

X射线荧光光谱法分析地质样品的应用技巧

Application Skills on Determination of Geological Sample by X-ray Fluorescence Spectrometry

  • 摘要: X射线荧光光谱法(XRF)具有制样简单、绿色环保、可同时测定多个元素等特点, 被广泛应用于勘查地球化学分析领域中, 其中粉末压片XRF是快速经济的主导方法.然而在大批量实际样品测试中, 如果分析者选择测量条件不当或者校正标准曲线不合理, 就会导致测量结果的粗大误差甚至测出不合逻辑的数据.本文对地质样品中的主要元素在测试中容易出现的技术问题作一具体分析:以钒元素为例, 用实验说明探测器的选择对于测量结果的重要性, 采用SC探测器可将V Kα线与Ti Kβ线分开, 而采用SC+PC探测器两元素的谱线发生重叠; 以硅酸盐中铁元素为例, 描述了不同的回归标准曲线对测量结果的影响; 对地质样品中低含量铌、钽的测定, 标准曲线要根据实际情况合理回归, 并将测试后的样品与化学方法对照, 结果相符.同时提出了硅酸盐、碳酸盐等地质样品的测量问题.对于土壤、水系沉积物、岩石地质样品, 一些元素之间会产生相互干扰, 以常见的造岩元素钛为例, 用实验证明铝和铁对钛的谱线确实有增强和吸收效应; 对于常见的碳酸盐类样品, 氯和铬的测量要考虑氧化钙的吸收增强效应, 必须添加氧化钙作为其吸收增强校正项, 才能保证测量结果可靠.针对硫元素的测定, 除了受到硫赋存状态的影响, 样品污染问题也是影响因素之一, 需要避免空气、实验室环境以及分析过程中对样品的污染.本文针对一些典型元素XRF分析提出的具体测量方案, 应用于实际地质样品测试可以获得满意的效果.

     

    Abstract: X-ray Fluorescence Spectrometry (XRF) has such advantages as simple sample preparation, green environmental protection and the simultaneous determination of multiple elements and is widely used in the exploration geochemistry analysis field. Pressed Powder X-ray Fluorescence is the dominant method for its rapid and economic application. However, when large quantities of samples are being tested, if the analysts' measurements conditions are improperly selected or the working curve correction is unreasonable, gross error will be caused in the measurement result. The technology problems encountered in the test of a certain element in geological samples is given a detailed analysis and discussed in this paper. Vanadium is chosen as an example, indicating that the choice of SC detector expounds the importance of correct selection of measurement conditions. For example, the detection of iron in silicate describes the effect of regression curves which work differently on the measurement results. For the determination of low content of niobium and tantalum in geological samples, work curves should be reasonably returned according to the practical situation, and the samples after testing should be compared with chemical methods, then the result can be considered as consistent. In soil, stream sediment, rocks and other geological samples, mutual interference between elements exists. The common rock forming element titanium was used as an example to prove that aluminum and iron in samples does have the absorption and enhancement effect on the spectral lines of titanium. For common carbonate samples, in the measuring of chloride and chromium the enhanced absorption effect of calcium oxide must be considered, and calcium oxide must be added as its enhanced absorption correction term, in order to ensure reliable measurement results. Finally, the problem of pollution of sulfur and the preventive measures were also analyzed. Some common measurement problem of silicate, carbonate in geological samples is presented, and the solution to the actual production is discussed.

     

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