A new method for precise measurement of the mass fractions of insoluble fluoride-forming elements (IFFEs) and high field-strength elements (HFSEs) in rock samples by ICP-QMS was developed. Unlike previous methods, in which the two elemental groups are measured separately using two solutions prepared from distinct sample aliquots (i.e., separate methods), this technique prepares a solution by acid digestion from a single sample aliquot, then divides the solution into two fractions that are dedicated to the measurement of IFFEs and HFSEs. The incorporation of IFFEs/HFSEs into insoluble fluorides during HF digestion was overcome by adjusting the Ca-Al-Mg composition of the sample by Al addition before acid digestion. The acceptable composition was Ca/(Ca+Al) < 0.43 and Mg/(Mg+Al) < 0.40 with hot plate digestion, whereas the limited condition of Ca/(Ca+Al) < 0.40, Mg/(Mg+Al) < 0.40 and Al/(Mg+Ca) < 1.86 was required for digestion under high pressure and temperature. For samples with an unacceptable composition, the change in Ca-Al-Mg composition by Mg/Ca addition should be prohibited because the reaction of HF with the added solution before sample decomposition forms fluorides that coprecipitate HFSEs. The developed method yielded mass fractions consistent with data from the separate methods (± 5%) and achieved a repeatability of < 4% for most elements.

中文翻译：

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ICP-QMS 通过同位素稀释-内标法同时测定岩石样品中的不溶性氟化物和高场强元素丰度

建立了一种利用ICP-QMS精确测量岩石样品中不溶性氟化物形成元素（IFFEs）和高场强元素（HFSEs）质量分数的新方法。与以前的方法不同，在以前的方法中，两个元素组是使用由不同的样品等分试样制备的两种溶液（即，单独的方法）分别测量的，这种技术通过酸消化从单个样品等分试样制备溶液，然后将溶液分成两部分，专用于IFFE和HFSE的测量。通过在酸消解之前添加铝来调整样品的 Ca-Al-Mg 组成，克服了在 HF 消解过程中将 IFFE/HFSE 掺入不溶性氟化物的问题。可接受的组成是 Ca/(Ca+Al) < 0.43 和 Mg/(Mg+Al) < 0.40，采用热板消解，而在高压和高温下消化需要 Ca/(Ca+Al) < 0.40、Mg/(Mg+Al) < 0.40 和 Al/(Mg+Ca) < 1.86 的有限条件。对于成分不可接受的样品，应禁止通过添加 Mg/Ca 来改变 Ca-Al-Mg 成分，因为在样品分解之前 HF 与添加的溶液反应会形成共沉淀 HFSE 的氟化物。开发的方法产生的质量分数与来自不同方法的数据一致 (± 5%)，并且大多数元素的重复性 < 4%。应禁止因添加 Mg/Ca 而改变 Ca-Al-Mg 组成，因为 HF 在样品分解之前与添加的溶液反应形成氟化物，从而使 HFSE 共沉淀。开发的方法产生的质量分数与来自不同方法的数据一致 (± 5%)，并且大多数元素的重复性 < 4%。应禁止因添加 Mg/Ca 而改变 Ca-Al-Mg 组成，因为 HF 在样品分解之前与添加的溶液反应形成氟化物，从而使 HFSE 共沉淀。开发的方法产生的质量分数与来自不同方法的数据一致 (± 5%)，并且大多数元素的重复性 < 4%。