High-precision stable zirconium isotope ratio measurements by double spike thermal ionization mass spectrometry
High-precision stable zirconium isotope ratio measurements by double spike thermal ionization mass spectrometry
复制标题
通过双尖峰热电离质谱法进行高精度稳定锆同位素比测量
DOI：
10.1039/c9ja00385a
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发表时间：
2020-04-01
影响因子：
3.4
通讯作者：
Liu, Yongsheng
中科院分区：
文献类型：
--
作者：
Feng, Lanping;Hu, Wenfeng;Liu, Yongsheng
提出了一种用热电离质谱（TIMS）准确测定地质样品中稳定锆同位素比值的新方法。钼的等压干扰在很大程度上消除灯丝加热过程中，并进一步减少离线钼干扰校正。该方法允许完全消除Mo干扰，即使Mo/Zr比高达1。通过使用单一DGA树脂柱和少量酸（15 mL 7 mol L−1 HNO 3和3 mL 1 mol L−1 HF），实现了从天然样品基质中分离Zr。在消化前将91 Zr-96 Zr双掺料与样品混合，这使得能够校正柱分离和质谱测量期间可能发生的同位素分馏。经对11种地质标准物质和标准物质的重复分析，δ 94 Zr的长期测量重现性一般优于±0.06‰（不确定度用2个标准偏差表示，以下简称2 SD）。用该方法测定的地质标准物质BHVO-2和AGV-2的Zr同位素比值与文献报道的MC-ICP-MS测定值一致，证实了该方法的准确性。这种新方法大大简化了化学分离过程，特别适用于复杂基体（特别是高Mo）样品的Zr同位素分析。
A new analytical method for the accurate and precise determination of stable zirconium isotope ratios in geological materials by thermal ionization mass spectrometry (TIMS) is presented. Isobaric interference from Mo was largely eliminated during filament heating and further reduced by off-line Mo interference correction. This methodology allows the complete elimination of Mo interference even with a Mo/Zr ratio up to 1. Separation of Zr from natural sample matrices was achieved by using a single DGA resin column with a small usage of acids (15 mL of 7 mol L−1 HNO3 and 3 mL of 1 mol L−1 HF). A 91Zr–96Zr double spike was admixed with samples before digestion, which enabled the correction of isotope fractionation that could occur during column separation and mass spectrometry measurement. The long-term measurement reproducibility of δ94Zr is generally better than ±0.06‰ (uncertainty represented by two standard deviations, hereinafter referred to as 2 SD), assessed by repeated analyses of Zr standard reference NIST SRM 3169 and eleven geological reference materials. The Zr isotope ratios of geological reference materials BHVO-2 and AGV-2 obtained in this study are consistent with the reported values measured by MC-ICP-MS, confirming the accuracy of the proposed method. This new method greatly simplifies the chemical separation process and is particularly suitable for Zr isotope analysis of complex matrix (especially for high Mo) samples.