| 金属同位素质谱中分析样品处理的基本原则与方法 |
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| 引用本文： | 李津,唐索寒,马健雄,朱祥坤.金属同位素质谱中分析样品处理的基本原则与方法[J].岩矿测试,2021(5):627-636. |
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| 作者姓名： | 李津 唐索寒 马健雄 朱祥坤 |
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| 作者单位： | 中国地质科学院地质研究所, 自然资源部同位素地质重点实验室, 自然资源部深地动力学重点实验室, 北京 100037 |
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| 基金项目： | 国家自然科学基金面上项目（41973020，41473005）；国家重点研发计划项目（2019YFA0708400） |
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| 摘 要： | 二十年来，国内外相继建立了多种金属（铁铜锌镁钙锂钼硒汞铬镉矾钡钛等）同位素的分析方法。金属同位素分析中的样品处理包括两个过程：样品的消解和样品中待测元素的分离纯化。为了获得真实、准确的金属同位素数据，样品处理过程必须遵守两个基本原则：①不引入待测元素以及可能会对待测元素同位素分析产生干扰的元素；②待测元素不发生损失。金属同位素分析常用的样品消解方法是酸溶法（包括高压闷罐法和微波消解法）。待测元素的分离纯化主要使用离子交换分离法。相同的树脂可以用于不同元素的化学分离，同一种元素也可以使用不同的树脂进行化学分离。不同类型样品的基质差异较大，需要不同的流程对待测元素进行分离。研究人员可以通过改变前人的分离流程，包括改变树脂的用量、变换淋洗液或用量、增加分离步骤等方法来满足不同样品的分离要求。本文提出了金属同位素样品处理中需要注意的一些细节：①如果消解样品时使用了高氯酸，必须将高氯酸在高温下彻底去除，因为残余的高氯酸具有强氧化性会使后续化学分离中使用的离子交换树脂失效，影响分离效果；②同一体积的树脂放入不同内径的交换柱中，树脂柱越细越长，淋洗液流速越慢、洗脱时间越长，并且待测元素洗脱出来越滞后；③离子交换过程中，每次加入的试剂体积越小，淋洗出来的元素越集中，分离效果越好。
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| 关 键 词： | 金属同位素 样品处理 消解 离子交换分离 |
| 收稿时间： | 2020/12/13 0:00:00 |
| 修稿时间： | 2021/6/29 0:00:00 |
Principles and Treatment Methods for Metal Isotopes Analysis |
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| LI Jin,TANG Suo-han,MA Jian-xiong,ZHU Xiang-kun.Principles and Treatment Methods for Metal Isotopes Analysis[J].Rock and Mineral Analysis,2021(5):627-636. |
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| Authors: | LI Jin TANG Suo-han MA Jian-xiong ZHU Xiang-kun |
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| Institution: | Institute of Geology, Chinese Academy of Geological Sciences;Key Laboratory of Isotope Geology, Ministry of Natural Resources;Key Laboratory of Deep-Earth Dynamics, Ministry of Natural Resources, Beijing 100037, China |
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| Abstract: | BACKGROUND: In the past twenty years, methods for metal isotopes analysis (iron, copper, zinc, magnesium, calcium, lithium, molybdenum, selenium, mercury, chromium, cadmium, alum, barium, titanium, etc.) have been established. The sample pretreatment during metal isotope analysis includes two processes:the digestion of the sample; and the separation and purification of the analyzed elements. In order to ensure the accuracy and precision of metal isotopes data, two general principles of sample treatment must be followed. Elements that may interfere with the isotope analysis of the analyzed elements should not be introduced into the analysis. The analyzed elements should not be lost during the experiment.OBJECTIVES: In order to understand the pretreatment methods for metal isotope analysis.METHODS: Common sample digestion methods and chemical separation (ion exchange separation) were introduced in detail and were discussed in this paper.RESULTS: The common sample digestion method for metal isotope analysis is the acid dissolution method (Teflon bombs and microwave digestion). The separation and purification of the element to be measured mainly uses the ion exchange separation method. The same resin can be used for the chemical separation of different elements, and the same element can also be chemically separated by using different resins. The matrices of different types of samples are quite different, and different processes are required to separate the analyzed elements. The separation requirements of different samples can be met by changing the separation process of the predecessors, including changing the resin or the amount, changing the eluent or the amount, and increasing the separation steps.CONCLUSIONS: Based on the authors'' experience, details should be paid attention to during treatments for metal isotope analysis:(1) HClO4 must be thoroughly removed at high temperature during sample digestion, because its strong oxidization can destroy the effectiveness of resins; (2) when the same volume of resin is put into the column, the thinner the column is, the slower the flow rate of the eluent, and the later elution of the elements to be measured; (3) the smaller the volume of the eluent added each time, the better the separation effect during ion exchange purification. |
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| Keywords: | metal isotopes sample treatment digestion ion exchange separation |
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