Measurements of mass-dependent Te isotopic variation by hydride generation MC-ICP-MS
Measurements of mass-dependent Te isotopic variation by hydride generation MC-ICP-MS
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DOI：
10.1039/c9ja00244h
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发表时间：
2020-02
影响因子：
3.4
通讯作者：
N. Wasserman;T. Johnson
中科院分区：
文献类型：
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作者：
N. Wasserman;T. Johnson
碲(Te)稳定同位素测量有可能在现代和古代环境中作为Te迁移性和氧化还原条件的示踪剂。在这里，我们提出了一种利用氢化物发生系统将Te有效地输送到等离子体中，结合120Te-124Te双尖峰的MC-ICPMS测量Te同位素比值的方法。这种方法可以精确测量δ130Te/126Te(2σ：0.09‰)，同时使用不到8.75ngTe的天然Te。虽然氢化物发生法通常比更传统的方法产生更高的灵敏度，但对于Te，在我们的仪器上，灵敏度与使用去溶雾化器获得的灵敏度相似。尽管如此，氢化物发生有一种有利的能力，可以排除干扰元素，如BA，并允许在某些情况下无需化学分离Te即可分析样品。我们还成功地证明了一种改进的离子交换法从天然沉积物中分离Te中的各种基质组分和等压干扰。利用这种方法对美国地质调查局标准参考物质、尾矿、古沉积物和土壤的多次消化分析表明，迄今为止陆地Te同位素组成的分布最大(δ130Te/126Te∼1.21‰)，缺乏可检测到的与质量无关的分馏。
Tellurium (Te) stable isotope measurements have the potential to serve as tracers of Te mobility and redox conditions in modern and ancient environments. Here, we present a method to measure Te isotope ratios by MC-ICP-MS utilizing a hydride generation system to efficiently deliver Te to the plasma, in combination with a 120Te–124Te double spike. This approach allows for precise δ130Te/126Te (2σ: 0.09‰) measurements while using less than 8.75 ng of natural Te. Although hydride generation methods usually produce higher sensitivity than more conventional methods, for Te, the sensitivity is similar, on our instrument, to that achieved using a desolvating nebulizer. Nonetheless, hydride generation has an advantageous ability to exclude interfering elements such as Ba and allow analysis of samples without chemical separation of Te in some cases. We also demonstrate successfully a modified ion exchange procedure to separate various matrix components and isobaric interferences from Te in natural sediments. Analyses of multiple digestions of USGS standard reference materials, mine tailings, ancient sediments, and soils utilizing this approach show the largest spread in terrestrial Te isotopic composition to date (δ130Te/126Te ∼ 1.21‰) and a lack of detectable mass-independent fractionation.