高铷/锶比地质样品中锶的共沉淀法快速分离及其高精度同位素测试  

Rapid Separation of Strontium from Geological Samples with High Rubidium/Strontium Ratios by Coprecipitation and Precise Determination of Strontium Isotopic

作　　者：魏双 奥琮 刘郁[3] 刘文刚 柳富田[1] 陈印 张健[1,2] 周红英[1,2] 王力强 WEI Shuang;AO Cong;LIU Yu;LIU Wen-Gang;LIU Fu-Tian;CHEN Yin;ZHANG Jian;ZHOU Hong-Ying;WANG Li-Qiang(Tianjin Center,China Geological Survey,Tianjin 300170,China;Key Laboratory of Uranium Geology,China Geological Survey,Tianjin 300170,China;State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局铀矿地质重点实验室,天津300170 [3]稀土资源利用国家重点实验室,中国科学院长春应用化学研究所,长春130022

出　　处：《分析化学》2020年第1期97-103,共7页Chinese Journal of Analytical Chemistry

基　　金：中国地质调查局项目(Nos.DD20190338,DD20190119-06);国家自然科学基金项目(No.41873066)资助~~

摘　　要：高铷/锶(Rb/Sr)比地质样品Sr同位素的分析测试中,利用NaOH对样品进行共沉淀处理可有效去除Na、K等基体元素和对Sr测试产生同质异位素干扰的Rb。通过对反应温度、时间、碱浓度等条件进行优化,确立了最佳反应条件。结果表明,以2 mL 5%(w/V)NaOH为沉淀剂,100℃反应1 h,可去除99%以上的Rb、Na、K和Al,Sr回收率优于96%。共沉淀反应后,利用AG50W×12阳离子交换树脂仅需进行一次过柱分离即可获得高纯度Sr。NaOH(99.99%)经过纯化后用于共沉淀反应,不会引入基体元素,Sr的流程空白小于182 pg。对8种不同Rb/Sr比的岩石标准样品(JR-2、BCR-2、BHVO-2、W-2、AGV-2、JG-3、JA-3、GSP-2)进行分离,结合高灵敏度热电离质谱仪(TIMS)获得高精度Sr同位素比值。结果表明,共沉淀-阳离子交换树脂分离流程具有适用范围广且稳定可靠的优点,同时可节省大量无机酸,且耗时较短。通过共沉淀法预富集Sr,为高Rb/Sr比地质样品的Sr同位素测试提供了一种新的分离途径,具有重要的应用价值。In analysis of strontium(Sr)isotope in geological samples with high rubidium(Rb)/Sr ratios,a large number of matrix elements(Na,K,etc.)and isobaric interference of Rb on Sr isotopic analysis were effectively removed by coprecipitation method using NaOH.The influence of reaction temperature,reaction time and alkali concentration were investigated,and the optimum reaction conditions were determined finally.The results showed that the removal rate of Rb,Na,K,Al was over 99%and the recovery of Sr was better than 96%by coprecipitation for 1 h using 2 mL of NaOH with a mass-to-volume ratio of 5%at 100℃.After coprecipitation,high purity Sr was obtained by a single separation and purification using AG50W×12 cation exchange resin.NaOH(99.99%)without adding excess matrix elements and the total procedure blanks of Sr was less than 182 pg.With this method,Sr isotope was separated from eight standard rock samples with different Rb/Sr ratios(JR-2,BCR-2,BHVO-2,W-2,AGV-2,JG-3,JA-3,GSP-2),and then high precision determination of Sr isotope ratios was obtained by highly sensitive thermal ionization mass spectrometer(TIMS).The result showed that the coprecipitation-cation exchange resin separation process had many advantages such as wide application range,stability and reliability,low consumption of inorganic acids and short reaction time.Preconcentration of Sr by the coprecipitation method provided a new separation way for Sr isotope determination in geological samples with high Rb/Sr ratios,showing an important application value.

关 键 词：地质样品 高铷/锶比 共沉淀法 阳离子交换树脂 锶同位素 

分 类 号：O65[理学—分析化学]