铬同位素纯化方法的比较研究  

Comparative Study on the Purification Methods for Chromium Isotopes Measurement

作　　者：李维涵 朱建明[1] 吴广亮 谭德灿 王静[2] LI Wei-han;ZHU Jian-ming;WU Guang-liang;TAN De-can;WANG Jing(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(Beijing),Beijing 100083,China;State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences Guiyang 550081,Chirm;University of Chinese Academy of Sciences,Beijing 100049.China)

机构地区：[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083 [2]中国科学院地球化学研究所,环境地球化学国家重点实验室,贵阳550081 [3]中国科学院大学,北京100049

出　　处：《矿物岩石地球化学通报》2019年第5期1024-1030,共7页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41473028,41273029)

摘　　要：铬(Cr)同位素已经发展成为重建古环境的氧化-还原条件和示踪Cr污染过程的有力手段。然而,对低Cr含量样品的Cr同位素测试仍然存在困难。为解决这一问题,我们使用两种低Cr标样BCR-2和SGR-1b比较了目前流行的3种Cr纯化方法,结果表明这些方法均存在回收率低或纯化效果差等问题。基于这一结果,我们认为Cr形态的不统一及其稳定性是影响Cr回收率的主要因素,并提出在添加50Cr-54Cr双稀释剂的情况下,使用2 mol/L HNO3-0.5%H2O2和盐酸羟胺统一Cr的形态,结合Cr(III)及其转化为较为稳定的Cr(VI)形态时利用阴、阳离子交换树脂可以将Cr与基质元素彻底分离,实现低Cr高基质样品的Cr同位素测试。The chromium(Cr)isotope has been developed to be a powerful tracer for reconstructing the redox condition of paleo-environment and tracing the Cr pollution process.However,there is still a challenge for determining Cr isotopes of samples with low Cr contents.In order to solve this problem,a comparative study on the three currently popular methods for purifying Cr has been carried out using two geological reference materials of BCR-2 and SGR-1 b with low Cr contents.The results show that these methods are not suitable for analyzing samples of low Cr contents owing to the poor purification and low recovery.Based on the results of the analysis,it was concluded that the disunity and stability of Cr speciation during separation procedures is the main factor affecting the high or low recovery of Cr.We therefore have suggested that when the 50Cr-54Cr double spike was added,the 2 mol/L HNO3-0.5%H2O2 and a small amount of hydroxylamine hydrochloride were used to unify the speciation of Cr(III),which was then converted to a more stable Cr(VI)state by oxidant.Finally,the anion(AG1-X8)and cation(AG50 W-X8)exchange resins were used to completely separate the Cr from the matrix elements of samples,in order to be capable to determine of Cr isotopes of samples containing low contents of Cr but high contents of matrix elements.

关 键 词：铬同位素 纯化方法 铬形态 优化流程 

分 类 号：P595[天文地球—地球化学]