摘要:
现有的地质样品中Pb、Sr、Nd分离分析方法是对Pb和Sr-Nd分别采用两份样品进行分离,多消耗一份样品量,因而制约了样品量少的研究。本文提出了基于HNO3-HF-HClO4混合酸熔融样品,采用AG1-X8、AG50W-X8和HDEHP组合离子交换柱,对同一份地质样品一次溶样,连续分离Pb、Sr、Nd。用该方法对国际标准样品AGV-2、BHVO-2中的Pb、Sr、Nd进行分离,回收率均优于95%,全流程空白分别为Pb<0.2 ng,Sr<1.5 ng,Nd<1.1 ng。用多接收器-电感耦合等离子体质谱(MC-ICP-MS)进行同位素比值测定,结果表明本研究提出的一份样品连续分离后的同位素测定结果与传统方法利用两份样品分别进行分离的结果在误差范围内完全一致。本文的研究可实现微量岩石样品的Pb、Sr、Nd同位素准确分析,对于珍贵样品的同位素组成研究具有重要意义。
关键词:
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Pb
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Sr
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Nd
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同位素组成
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连续分离
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一次溶样
Abstract:
Two individual solutions were required by the traditional chemical separation procedures to separate Pb and Sr-Nd, however, it was difficult for limited geological samples. In this study, we presented an improved chemical method for Pb, Sr and Nd separation from the same single dissolution. The procedure consisted of the following two steps: (1) the sample was digested with HNO3-HF-HClO4 mixed acids. (2) Pb, Sr and Nd were separated from the matrix by a combination of AG1-X8, AG50W-X8 and HDEHP ion exchange columns. The recoveries of the samples were better than 95%. The total procedural blanks measured for Pb, Sr, and Nd were lower than 0.2 ng, 1.5 ng and 1.1 ng, respectively. Analytical feasibility, flexibility and reproducibility of Pb, Sr and Nd isotope were verified by USGS rock standards of AGV-2 and BHVO-2. The isotopic compositions of Pb, Sr and Nd were measured by Multi-Collector Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS). The results were consistent of the improved method and the traditional chemical procedures within the uncertainties. It indicated that the presented technique has great potential application of Pb, Sr and Nd isotopic measurements for limited or rare geological rocks.
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