Trace element analysis with the electron microprobe: New data and perspectives
Trace element analysis with the electron microprobe: New data and perspectives
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DOI：
10.2138/am-1999-1-207
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发表时间：
1999-02
影响因子：
3.1
通讯作者：
M. Fialin;H. Rémy;C. Richard;C. Wagner
中科院分区：
文献类型：
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作者：
M. Fialin;H. Rémy;C. Richard;C. Wagner
摘要 这项工作提出了一种使用电子微探针 (EMP) 进行痕量元素分析的程序。该方法通过对由花岗岩、花岗闪长岩、安山岩、辉绿岩和玄武岩成分的参考岩粉制备的七种玻璃进行分析来证明。对熔化过程进行了调整，以防止挥发性元素的损失并获得均质的样品。主要和次要（1000 ppm 以上）元素的常规分析程序得出的结果与公布的值相当吻合。本研究中提出的方法产生的检测限低至： (1) 当使用第一行过渡金属（Cr 和 Ni）的 Kα 峰时，检测限低至 6-8 ppm； (2) 23 ppm，具有软 Lα 峰（Y、Zr 和 Sr）； (3) 15 ppm，具有高能Lα峰（稀土元素）； (4) 35 ppm 重元素（Pb 和 Th）的 Ma 峰。这些限制是在 35 kV 和 500 nA 光束的总计数时间（峰值 + 两次背景测量）约 15 分钟后达到的。对于浓度高于 13 ppm 的第 1 组元素、第 2 组元素的浓度为 35 ppm、第 3 组元素的浓度为 25 ppm、第 4 组元素的浓度为 55 ppm，重量百分比浓度的精度 (± 2σ) 低于 50%。在本工作中，采用商业软件包进行定量痕量元素分析。一项修改针对的是光束敏感材料，测量所需的长计数时间需要分为子集（10-20 秒计数），每个子集从样品表面的不同位置采集，以最大限度地减少损坏。这种分析模式称为“多站点”模式。
Abstract This work presents a procedure developed for trace element analysis using the electron microprobe (EMP). The method is demonstrated by analysis of seven glasses prepared from reference rock powders, with compositions of granite, granodiorite, andesite, diabase, and basalt. The melting process was adapted to prevent the loss of volatile elements and to obtain homogeneous samples. A routine procedure for analysis of major and minor (above 1000 ppm) elements yielded results in fairly good agreement with published values. The methods presented in this study produced detection limits as low as: (1) 6-8 ppm when the Kα peaks of transition metals of the first row (Cr and Ni) were used; (2) 23 ppm with soft Lα peaks (Y, Zr, and Sr); (3) 15 ppm with high-energy Lα peaks (rare earth elements); and (4) 35 ppm with the Ma peaks of heavy elements (Pb and Th). These limits were achieved after total counting times (peak + two background measurements) of about 15 min with a beam of 35 kV and 500 nA. Precision (± 2σ) on the weight percent concentrations was below 50% for concentrations above 13 ppm for group 1 elements, 35 ppm for group 2, 25 ppm for group 3, and 55 ppm for group 4. In the present work, a commercial software package was adapted for quantitative trace element analysis. One modification addresses beam-sensitive materials for which the long counting times required for measurements need to be divided into subsets (10-20 s count), each acquired from different sites of the sample surface, to minimize damage. This analytical mode is referred to as ‘‘multi-site’’ mode.