硫化物原位微区硫-铅同位素及铂族元素标准物质研制

The sulfur isotope, lead isotope and platinum-group elements (PGEs) have been widely used as the highly effective tracers in geoscience. Recently, in situ micro-analysis of S-Pb isotopes and PGE concentration in sulfides using the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have become popular in the field of geochemistry analysis. However, the development of micro-analysis of S-Pb isotopes and PGEs concentration in sulfides by LA-ICP-MS is hampered by the lack of reference materials of sulfides. This project plan to synthesize sulfide standard materials for the micro-analysis of S-Pb isotopes and PGEs concentration. The nano-sulfide powder will be used to improve the homogeneity of S-Pb isotope and PGEs in sulfides. The method of sintering at high temperature will be used to synthesize different matrix sulfides to match most of natural sulfides. The synthesized sulfide reference materials will be tested by LA-(MC)-ICP-MS for assessing the homogeneity and measured by gas-source mass spectrometry, solution-MC-ICP-MS and solution-ICP-MS for obtaining the reference values of S isotopes, Pb isotopes and PGEs concentration, respectively. Then, this project will provide a series of sulfide reference materials to the micro-analysis of S-Pb isotopes and PGEs concentration in the actual geological samples and study about the matrix effect induced by the interaction between the laser ablation and sulfide materials.

硫化物硫-铅同位素和铂族元素（简称PGEs）作为有效的地球化学示踪剂，受到地质学家长期关注。利用激光剥蚀电感耦合等离子体质谱（LA-ICP-MS）测定硫化物硫-铅同位素及PGEs已成为微区地球化学热门领域。但是缺乏理想的硫化物标准物质限制了LA-ICP-MS在硫化物微量元素及同位素测定的发展。本项目拟开展硫化物硫-铅同位素及PGEs标准物质研制工作。采用超细样品加工技术制备纳米硫化物粉末，解决元素分布均匀性问题。利用高温熔融法合成不同基体硫化物以匹配大部分天然硫化物基体。合成的硫化物标准物质将采用LA-(MC)-ICP-MS评价其硫-铅同位素及PGEs的均匀性，采用气体同位素质谱和溶液-(MC)-ICP-MS进行硫、铅同位素和PGEs定值。合成的硫化物标准物质将应用于实际地质样品的原位微区研究和探讨激光剥蚀硫化物矿物的基体效应影响。

准确测定硫化物样品中硫-铅同位素和PGEs含量是开展相关地质工作的重要前提。近年来，LA-(MC)-ICP-MS技术已成为硫化物原位微区分析的重要技术手段。但是，缺乏基体匹配的标准物质成为限制该技术广泛使用的重要因素之一。本次研究开展了大量纳米硫化物合成实验和粉末颗粒高温熔融制备硫化物玻璃实验，实现了利用机械研磨手段，化学合成手段两种不同方式合成纳米级硫化物颗粒。创新性提出水热合成技术制备初始纳米级硫化物颗粒，介质中的微量元素可以伴随纳米颗粒生长选择性地进入到颗粒物中，使制备出的纳米粉末具有均匀的元素分布。研究制备的纳米硫化铁粉末中可以赋存PGEs、Re、Au、Pb等元素。硫化物铁粉末压片样品中微量元素分布均匀性优于7%，S-Pb同位素分布也达到要求，可以满足原位微区元素成分分析的需要。本次研究最终合成的4个具有不同铂族元素含量和均匀S-Pb同位素的硫化铁已经被成功应用于实际地质样品的硫化物元素和同位素分析，取得了很好的分析结果。受资助期间，发表第一作者及通讯作者论文7篇，其中6篇论文发表在影响因子>3.0的国际SCI期刊上。并多次在国内相关领域大会上做特邀报告。