MC-ICP-MS准确测定地质样品中锂同位素组成  

Accurate Analysis of Lithium Isotopic Composition of Geological Samples by MC-ICP-MS

作　　者：蔺洁[1] 刘勇胜[1] 胡兆初[1] 陈康[1] 陈海红[1] 宗克清[1] 高山[1] 

机构地区：[1]中国地质大学(武汉)地球科学学院,地质过程与矿产资源国家重点实验室,湖北武汉430074

出　　处：《矿物岩石地球化学通报》2016年第3期458-464,400-401,共7页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(41125013);地质过程与矿产资源国家重点实验室基金项目(MSFGPMR201504);中央高校基本科研业务费专项(CUG090105)

摘　　要：以一根阳离子交换树脂填充的石英交换柱,使用1 mol/L HNO_3/80%（V/V）CH_3OH作为淋洗液可实现对不同性质标样中Li元素的化学分离与富集;讨论了Li淋洗曲线与样品岩性和Mg：Li值的关系,建立了可靠的岩石样品的Li化学分离流程。研究发现,化学分离得到的Li接收液中残余离子不同对Li同位素准确测定的影响不同,但将残余离子浓度控制在一定范围内时（～10）,可以忽略残余离子的影响。使用5%NaCl溶液消除Li的记忆效应后,样品和标样中Li浓度和HNO_3浓度不匹配对Li同位素准确测定的影响大大降低。因此,该方法无须严格基体匹配即可进行Li同位素比值的准确测定。A method for accurate measurement of Li isotopic ratio by SSB-MC-ICP-MS has been set up. Li purification can be implemented by single chemical separation method,in which 1 mol / L HNO_3/80%（V/V）CH_3OH was used as the eluent. Effects of sample type and Mg∶Li in samples on the elution process were also investigated. The residual ions in the sample after separation can compromise the accuracy and precision of Li isotopic ratios,but the results show no discernable matrix-induced mass discrimination on Li isotopic measurement even though the residual ion / Li ratio was up to 10.After the Li memory effect being eliminated with the 5% NaCl solution,the effect arouse by the mismatch of Li and acid concentration in sample and standard can be reduced. So a non-strict-matrix-matched method can be applied to accurate and precise measurement of Li isotopic ratios.

关 键 词：锂同位素 MC-ICP-MS 国际标样 

分 类 号：P597[天文地球—地球化学]