地质样品铊同位素分析预处理方法优化  

Optimization of Pretreatment Method for Tl Isotope Analysis of Geological Samples

作　　者：柒锦捷 余红霞 徐庆鸿[1] 袁永海[1,2] 杨锋[1,2] 张惠评 QI Jinjie;YU Hongxia;XU Qinghong;YUAN Yonghai;YANG Feng;ZHANG Huiping(College of Earth Sciences,Guilin University of Technology,Guilin 541006,China;Guangxi Key Laboratory of Hidden Metal Mineral Exploration,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541006 [2]桂林理工大学,广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《岩矿测试》2024年第2期213-223,共11页Rock and Mineral Analysis

基　　金：国家重点研发计划项目(2021YFC2900100);广西研究生创新项目(YCBZ2022119)。

摘　　要：铊同位素体系可以示踪天体演化、古环境变化、矿床成因及污染物迁移等地质过程。然而,目前用于铊同位素分析的样品消解和离子交换方法耗时较长,往往需要两周甚至更久;为了提高化学前处理效率,本文采用微波消解法分解样品,以AG1-X8阴离子交换树脂纯化铊,采用多接收器电感耦合等离子体质谱(MC-ICP-MS)测试,仪器的质量歧视用铅同位素标准溶液(NIST SRM981)校正。通过考察消解条件、淋洗曲线和基质效应,结果表明:采用微波消解法,在2mL硝酸-2mL氢氟酸-0.5mL高氯酸的混合酸体系中选用适当的消解程序可以将0.2g土壤标准物质GBW07406消解完全,总耗时不超过2h;利用AG1-X8树脂,上样后,依次以2mL 2mol/L硝酸-1%溴水淋洗6次、2mL超纯水淋洗1次和2mL 0.1mol/L盐酸-6%二氧化硫淋洗5次(收集铊),可有效地纯化铊;常见共存元素的干扰实验结果显示,树脂填充量为2mL时,该淋洗流程所允许上样溶液中含有三价铁和三价铝离子的量分别不应超过2.56mmol和4.90mmol,否则会使铊的回收率降低。将此方法应用于4个地质标准物质中铊同位素比值的测定,ε^(205)TlGSB Tl的精密度(2SD,n=6)均优于0.3;与文献的结果对比显示,标准物质NOD-P-1、GBW07406和GSP-2的ε^(205)Tl差值(ε^(205)Tl_(NIST 997)-ε^(205)Tl_(GSB Tl))均为0.8,NOD-A-1的ε^(205)Tl差值为0.7,说明方法具有较好的准确性;此外,可以估算标准物质GSB 04-1758-2004相对于NIST 997的ε^(205)Tl值应约等于0.8。The thallium(Tl)isotope system can be utilized to track various geological processes,but the current sample digestion and ion exchange methods used for Tl isotope analysis take a long time.To improve the efficiency of chemical pretreatment of samples for Tl isotope analysis,the samples were decomposed by the microwave digestion method.In the mixed acid system of 2mL HNO_(3),2mL HF and 0.5mL HClO_(4),0.2g of GBW07406 could be completely dissolved by selecting the digestion procedure.The slurry was then loaded on AG1-X8 resin,followed by eluting with 2mL 2mol/L HNO_(3)-1%Br_(2) for 6 times,2mL H_(2)O for 1 time,and 2mL 0.1mol/L HCl-6%SO2 for 5 times(Tl collection).The amount of Fe^(3+)and Al^(3+)allowed in the sample solution should not exceed 2.56mmol and 4.90mmol respectively,otherwise the recovery rate of Tl will be reduced.Measurementε^(205)Tl values for four geological reference materials(NOD-P-1,NOD-A-1,GBW07406 and GSP-2)by multi-collector inductively coupled plasma-mass spectrometry(MC-ICP-MS)showed a good precision(2SD better than 0.3,n=6)and a fixed difference of 0.8 compared with the value in the literature,indicating that theε^(205)Tl value of GSB04-1758-2004 with respect to NIST 997 should be approximately equal to 0.8.

关 键 词：硝酸-氢氟酸-高氯酸 微波消解 AG1-X8阴离子交换树脂 铊同位素组成 多接收器电感耦合等离子体质谱法 

分 类 号：O657.63[理学—分析化学]