岩矿测试

文章摘要

赵悦,侯可军,田世洪,杨丹,苏嫒娜.常用锂同位素地质标准物质的多接收器电感耦合等离子体质谱分析研究[J].岩矿测试,2015,34(1):28-39

ZHAO Yue,HOU Ke-jun,TIAN Shi-hong,YANG Dan,SU Ai-na.Study on Measurements of Lithium Isotopic Compositions for Common Standard Reference Materials Using Multi-Collector Inductively Coupled Plasma-Mass Spectrometry[J].Rock and Mineral Analysis,2015,34(1):28-39.DOI:10.15898/j.cnki.11-2131/td.2015.01.004

常用锂同位素地质标准物质的多接收器电感耦合等离子体质谱分析研究

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Study on Measurements of Lithium Isotopic Compositions for Common Standard Reference Materials Using Multi-Collector Inductively Coupled Plasma-Mass Spectrometry

投稿时间：2014-08-28 修订日期：2014-12-15

DOI：10.15898/j.cnki.11-2131/td.2015.01.004

中文关键词: 锂同位素标准物质样品量基质效应多接收器电感耦合等离子体质谱法

英文关键词: lithium isotopes standard reference materials sample size matrix effects Multi-collector Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS)

基金项目:国家自然科学基金面上项目(41373014,41173003);国土资源地质大调查项目(12120113016200);公益性行业科研专项(201011027)

作者	单位
赵悦	中国地质科学院矿产资源研究所, 国土资源部成矿作用与资源评价重点实验室, 北京 100037
侯可军	中国地质科学院矿产资源研究所, 国土资源部成矿作用与资源评价重点实验室, 北京 100037
田世洪	中国地质科学院矿产资源研究所, 国土资源部成矿作用与资源评价重点实验室, 北京 100037
杨丹	中国地质科学院矿产资源研究所, 国土资源部成矿作用与资源评价重点实验室, 北京 100037
苏嫒娜	中国地质科学院水文地质环境地质研究所, 河北石家庄 050061

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中文摘要:

锂同位素研究是非传统稳定同位素地球化学研究的前沿,已广泛应用于从地表到地幔的岩石圈及流体等固体地球科学的研究领域.准确测定锂同位素比值是应用该同位素体系的前提.本文报道了国际上7种常用地质标准物质(BHVO-2、JB-2、BCR-2、AGV-2、NKT-1、L-SVEC、IRMM-016)的锂同位素组成数据.分析中采用硝酸-氢氟酸混合酸消解岩石标准样品,通过3根阳离子交换树脂(AG50W-X8,200～400目)填充的聚丙烯交换柱和石英交换柱对锂进行分离富集,利用Neptune型多接收器电感耦合等离子体质谱(MC-ICP-MS)测定锂同位素比值,使用标准-样品交叉法(SSB)校正仪器的质量分馏.实验得到这7种常用地质标准物质的锂同位素组成与测试精度(2SD)分别为:δ⁷Li_{BHVO-2—L-SVEC}=4.7‰±1.0‰(n=53),δ⁷Li_{JB-2—L-SVEC}=4.9‰±1.0‰(n=20),δ⁷Li_{BCR-2—L-SVEC}=4.4‰±0.8‰(n=8),δ⁷Li_{AGV-2—L-SVEC}=6.1‰±0.4‰(n=14),δ⁷Li_{NKT-1—L-SVEC}=9.8‰±0.2‰(n=3),δ⁷Li_{L-SVEC—L-SVEC}=-0.3‰±0.3‰(n=10),δ⁷Li_{IRMM-016—L-SVEC}=0.0‰±0.5‰(n=10),这些数据在误差范围内与国际上已发表的数据一致.Li同位素分析精度可以达到大约0.5‰,长期的分析精度即外部重现性≤±1.0‰,达到了国际同类实验室水平.7种常用地质标准物质的锂同位素组成数据的发表为锂同位素研究提供了统一的标准,使地质样品的锂同位素数据的质量监控成为可能.在基质效应的研究中,使用不同量的IRMM-016配制的标准溶液过柱,深入探讨了样品量对锂同位素测定值的影响,结果表明,在现有测试精度下,只要分析样品的锂含量达到100 μg/L,且不超过树脂的承载量,样品的锂同位素组成在误差范围内与真值吻合,样品量的大小不影响锂同位素测定结果的准确性.

英文摘要:

Non-traditional lithium isotope is a frontier in isotope geochemistry and has been applied to the studies of Solid Earth Sciences, such as the lithosphere and fluids from the Earth's surface to the mantle. Lithium isotopic compositions of 7 standard reference materials BHVO-2, JB-2, BCR-2, AGV-2, NKT-1, L-SVEC and IRMM-016 are reported in this paper. The rock standards were digested with HNO₃-HF mixed acids. Cation exchange resin AG50W-X8 was used for the separation of Li from other elements. Li isotope ratios were determined by Multi-Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS), and isotopic mass fractionation was calibrated by standard-sample bracketing. The Li isotopic compositions and the analytical uncertainties (reported in 2SD) of analyzed standard reference materials were: ⁷Li_{BHVO-2-L-SVEC}=4.7‰±1.0‰ (n=53), ⁷Li_JB-2-L-SVEC=4.9‰±1.0‰ (n=20), ⁷Li_BCR-2-L-SVEC=4.4‰±0.8‰ (n=8), ⁷Li_AGV-2-L-SVEC=6.1‰±0.4‰ (n=14), ⁷Li_NKT-1-L-SVEC=9.8‰±0.2‰ (n=3), ⁷Li_{L-SVEC-L-SVEC}=-0.3‰±0.3‰ (n=10), ⁷Li_{IRMM-016-L-SVEC}=0.0‰±0.5‰ (n=10). The results were in good agreement with published data within analytical uncertainties. The accuracy of this method is about ±0.5‰ and the long-term external precision (2SD) of replicate analyses including the entire pretreatment procedure is less than ±1.0‰, and is similar to the state of the art method. The reported data of 7 standard reference materials provided a new standard framework for Li isotope research, and enabled the evaluation of the quality of data retrieved from geological samples. The influence of sample size was also assessed by loading different amounts of separated IRMM-016 solutions. The results show that when the lithium concentration has reached 100 μg/L, the measured lithium isotopic compositions are in coincidence with the accepted value within uncertainty, and the sample size does not affect the accuracy of measurements.

主管单位：	中国科学技术协会
主办单位：	中国地质学会岩矿测试技术专业委员会国家地质实验测试中心