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高校地质学报 ›› 2024, Vol. 30 ›› Issue (02): 133-141.DOI: 10.16108/j.issn1006-7493.2023004

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NaOH 碱熔法在硅酸盐硼同位素测试中的应用

李正辉1,蔡 悦2*,魏海珍3,李 烨4,张微微4,李百蝉4   

  1. 1. 东华理工大学 核资源与环境国家重点实验室,南昌 330013;
    2. 中国科学院 南京地质古生物研究所 现代古生物学和地层学国家重点实验室, 南京 210008;
    3. 南京大学 内生金属矿床成矿机制研究国家重点实验室,地球科学与工程学院,南京 210023;
    4. 中国科学院 南京地质古生物研究所 实验技术中心, 南京 210008
  • 出版日期:2024-04-20 发布日期:2024-04-20

NaOH Alkaline Fusion Method for B Isotope Analysis of Silicates

LI Zhenghui1,CAI Yue2*,WEI Haizhen3,LI Ye4,ZHANG Weiwei4,LI Baichan4   

  1. 1. State Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013, China;
    2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in
    Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China;
    3. State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China;
    4. Experimental Technologies Center, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and
    Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China
  • Online:2024-04-20 Published:2024-04-20

摘要: 硼同位素是地球与行星科学研究中的一个重要工具,但是精确测量硅酸盐的硼同位素还存在一定的挑战,其主要原因源于样品消解。碱熔法是一种适合于硅酸盐样品的熔样方法。目前用于测量硅酸盐硼同位素的碱熔法采用昂贵的铂金或者玻璃碳坩埚和较高的助熔剂比例,容易在前处理过程中造成硼损失。为了实现硅酸盐样品的完全消解并避免硼的损失,文章报道一种使用银坩埚的NaOH碱熔法。该方法采用5:1的助熔剂与样品质量比,以及改进的溶样方法,实现了样品的完全消解并有效地避免了硼的流失。结合改进的硼特效树脂分离提纯技术和多接收电感耦合等离子体质谱仪(MC-ICP-MS)测量流程,文章报道了五个硅酸盐国际标样的硼同位素组成和硼含量数据。实验结果与国内外发表的数据在误差范围内一致。这个绿色且高效的方法对硅酸盐硼同位素研究具有重要意义。

关键词: 硼同位素, 碱熔法, 离子交换, 多接收电感耦合等离子体质谱仪

Abstract: Boron(B) isotope analysis is an important tool in the research of earth and planetary science. However, challenges still exist for precise and accurate measurements of boron isotope ratios of silicate material due to the challenges in sample digestion.
Alkaline fusion is a suitable sample dissolution method for boron isotope analysis in silicates. At present, alkaline fusion  methods require expensive platinum or glassy carbon crucibles as well as high flux-to-sample ratios. Additionally, the existing methods used for dissolving the fusion cake may cause boron loss. To achieve full dissolution and effectively prevent B loss, this study reports an improved alkali fusion method using sodium hydroxide and silver crucibles with a low flux-to-sample mass ratio of 5:1. Full dissolution was achieved through gentle heating in the presence of water combined with a stepwise dissolution procedure, which effectively prevented B loss during the dissolution of the fused alkaline cake. Using this improved procedure for dissolution, Amberlite IRA743 B-specific resin for B purification, and a multi-collector inductively coupled plasma mass spectrometer (MCICP- MS) for isotope analysis, we report boron isotope compositions and concentrations data for five silicate international standards. The results are consistent with the published data within analytical uncertainties. This safe and efficient method will greatly facilitate B isotope research of silicates.

Key words: boron isotope, alkaline fusion, ion-exchange chromatography, MC-ICP-MS

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