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密闭酸溶-电感耦合等离子体发射光谱/质谱法测定花岗伟晶岩中32种微量元素

Determination of 32 Trace Elements in Granite Pegmatite by Inductively Coupled Plasma-Optical Emission Spectrometry and Mass Spectrometry with Closed Acid Dissolution

  • 摘要: 花岗伟晶岩富集锂铍铷铯铌钽等稀有金属元素,准确测定其中的大离子亲石元素、高场强元素和稀土等微量元素,可用于判断成矿流体物质来源、成岩构造环境。目前的测试方法研究主要集中在锂铍铷铯铌钽等少数元素,样品消解方法有四酸敞开法、五酸敞开法、密闭酸溶法等,存在难溶矿物分解不完全、锆铪钍铀和稀土等元素回收率偏低等问题。本文对比了盐酸-硝酸-氢氟酸-高氯酸敞开消解法、盐酸-硝酸-氢氟酸-高氯酸-硫酸敞开消解法、硝酸-氢氟酸密闭消解法三种方法的分解效果。结果表明:四酸消解法中,铌钽锆铪钨和重稀土元素结果严重偏低;五酸消解法由于采用硫酸-氢氟酸-过氧化氢体系提取,有效地防止了铌钽的水解,铌钽钨等元素测定结果准确,但锆铪钡铅和轻稀土元素测定结果偏低。硝酸-氢氟酸密闭消解法使用王水代替硝酸进行残渣复溶,促进了铌钽锆铪和稀土等元素的复溶,采用电感耦合等离子体发射光谱和质谱法(ICP-OES/MS)可以准确测定花岗伟晶岩中稀有金属、稀土元素等32种元素,方法检出限为0.004~2.50μg/g,精密度(RSD,n=12)为1.0%~8.3%。将该方法应用于8种花岗岩、伟晶岩及稀有金属矿标准物质和三种类型实际样品的测定,标准物质的测定值与标准值基本相符。

     

    Abstract: Accurate determination of large ion lithophile elements, high field strength elements and rare earth elements in granite pegmatite can be used to judge the source of ore-forming fluid materials and the diagenetic tectonic environment. There are some problems in the sample determination process, such as incomplete decomposition of insoluble minerals and low recovery of elements like Zr, Hf, Th, U and rare earth elements. This article compared the decomposition effects of three methods. The results indicate that the two open digestion methods can lead to lower test results for elements such as Zr, Hf, and W, etc. In the closed digestion method, aqua regia was used instead of HNO3 for residual redissolution, which promotes the redissolution of elements such as Nb, Ta, Zr, Hf, rare earth elements, etc. ICP-OES and ICP-MS can accurately determine 32 trace elements in granite pegmatite. The detection limit of the method was between 0.004μg/g and 2.50μg/g, with a precision of 1.0%−8.3% (RSD, n=12). The method was applied to the determination of 8 types of granite, pegmatite, rare metal ore reference materials and 3 types of actual samples. The measured values of the reference materials were consistent with the standard values. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202307310105.

     

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