MC-ICP-MS测定岩石样品中锌同位素组成

The determination of zinc isotopic compositions in rock samples by MCICP-MS

锌同位素示踪技术在反演成矿过程、示踪污染源和示踪深部碳循环中都起着重要的作用,但是复杂的基质组成及锌元素含量水平的高低限制岩石样品中锌同位素组成的准确测定。本实验基于多接收电感耦合等离子体质谱仪(MC-ICP-MS)的测试方式对不同基质类型的岩石样品中锌同位素的分析方法进行探究,主要包括样品的消解方式、锌的分离纯化及干扰离子的影响等。实验采用AGMP-1(38~75μm)树脂进行分离提纯,分析过程使用标准-样品交叉法(SSB)对仪器产生的质量歧视进行校正,利用CAGS-Zn同位素标准溶液监控仪器的长期稳定性。结果显示:GBW07105、BCR-2和BIR-1a地质标准样品的锌同位素组成分别为:δ^(66)Zn_(GBW07105-IRMM-3702)=0.25‰±0.06‰、δ^(66)Zn_(BCR-2-IRMM-3702)=-0.07‰±0.06‰和δ^(66)Zn_(BIR-1A-IRMM-3702)=-0.09‰±0.01‰,测试结果在误差范围内与国际上已报道的值一致,验证此方法的准确性和可行性。本实验建立一种实验流程本底较低、干扰离子去除率高和分离程序适用性强的岩石样品锌同位素分析方法,有效分析7种岩性不同的岩石样品中锌同位素组成,为精准测量复杂基质样品中锌同位素组成提供有力的方法支撑。

Zinc isotope tracing technology plays a significant role in the inversion of ore-forming processes,tracing of pollution sources and deep carbon cycles.However,the complex matrix composition and the varying levels of zinc content constrain the accurate determination of zinc isotopic compositions in rock samples.This study explored an analytical method for zinc isotope in rock samples of different matrix types based on the testing method of MC-ICP-MS,which mainly included the dissolution method of samples,the separation and purification of zinc,and the impact of interfering ions.The experiment used AGMP-1(38-75μm)resin for separation and purification,and the analysis process employed the standard-sample bracketing method(SSB)to correct for mass bias produced by the instrument.The long-term stability of the instrument was monitored using the CAGS-Zn isotope standard solution.The zinc isotopic compositions of the GBW07105,BCR-2,and BIR-1a geological standard samples were measured to be:δ^(66)Zn_(GBW07105-IRMM-3702)=0.25‰±0.06‰,δ^(66)Zn_(BCR-2-IRMM-3702)=-0.07‰±0.06‰,δ^(66)Zn_(BIR-1A-IRMM-3702)=-0.09‰±0.01‰,respectively.The test results are consistent with the internationally reported values within the error range,verifying the accuracy and feasibility of this method.This study has developed an analytical method for zinc isotope analysis in rock samples,which is characterized by a low procedural blank,high interference removal efficiency,and strong applicability of the separation procedure.Using this method,we effectively analyzed the zinc isotope compositions of seven rock samples with different lithologies,and provided robust methodological support for accurately measuring zinc isotope compositions in complex matrix samples.