Steinhoefel Grit, Beck Kristina K, Benthien Albert, Richter Klaus-Uwe, Schmidt-Grieb Gertraud M, Bijma Jelle
Helmholtz-Zentrum für Polar- und Meeresforschung, Alfred-Wegener-Institut, Bremerhaven, Germany.
Universität Bremen, Bremen, Germany.
Rapid Commun Mass Spectrom. 2023 Jul 15;37(13):e9508. doi: 10.1002/rcm.9508.
Boron isotopes are a powerful tool for pH reconstruction in marine carbonates and as a tracer for fluid-mineral interaction in geochemistry. Microanalytical approaches based on laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) often suffer from effects induced by the sample matrix. In this study, we investigate matrix-independent analyses of B isotopic ratios and apply this technique to cold-water corals.
We employ a customized 193 nm femtosecond laser ablation system (Solstice, Spectra-Physics) coupled to a MC-ICP-MS system (Nu Plasma II, Nu Instruments) equipped with electron multipliers for in situ measurements of B isotopic ratios ( B/ B) at the micrometric scale. We analyzed various reference materials of silicate and carbonate matrices using non-matrix matched calibration without employing any correction. This approach was then applied to investigate defined increments in coral samples from a Chilean fjord.
We obtained accurate B isotopic ratios with a reproducibility of ±0.9‰ (2 SD) for various reference materials including silicate glasses (GOR132-G, StHs6/80-G, ATHO-G and NIST SRM 612), clay (IAEA-B-8) and carbonate (JCp-1) using the silicate glass NIST SRM 610 as calibration standard, which shows that neither laser-induced nor ICP-related matrix effects are detectable. The application to cold-water corals (Desmophyllum dianthus) reveals minor intra-skeleton variations in δ B with average values between 23.01‰ and 25.86‰.
Our instrumental set-up provides accurate and precise B isotopic ratios independently of the sample matrix at the micrometric scale. This approach opens a wide field of application in geochemistry, including pH reconstruction in biogenic carbonates and deciphering processes related to fluid-mineral interaction.
硼同位素是用于重建海洋碳酸盐中pH值的有力工具，也是地球化学中流体-矿物相互作用的示踪剂。基于激光烧蚀多接收电感耦合等离子体质谱法（LA-MC-ICP-MS）的微分析方法常常受到样品基质所引起的效应的影响。在本研究中，我们研究了硼同位素比值的基质无关分析，并将该技术应用于冷水珊瑚。
我们使用了一个定制的193纳米飞秒激光烧蚀系统（Solstice，光谱物理公司），该系统与一个配备电子倍增器的MC-ICP-MS系统（Nu Plasma II，Nu仪器公司）相连，用于在微米尺度上原位测量硼同位素比值（¹¹B/¹⁰B）。我们使用非基质匹配校准分析了各种硅酸盐和碳酸盐基质的参考物质，而不采用任何校正。然后将该方法应用于研究来自智利峡湾的珊瑚样品中的特定增量。
我们以±0.9‰（2标准差）的再现性获得了各种参考物质准确的硼同位素比值，这些参考物质包括硅酸盐玻璃（GOR132-G、StHs6/80-G、ATHO-G和NIST SRM 612）、粘土（IAEA-B-8）和碳酸盐（JCp-1），使用硅酸盐玻璃NIST SRM 610作为校准标准，这表明既未检测到激光诱导的基质效应，也未检测到与ICP相关的基质效应。应用于冷水珊瑚（石芝珊瑚）显示出δ¹¹B在骨骼内部的微小变化，平均值在23.01‰至25.86‰之间。
我们的仪器装置在微米尺度上能够提供与样品基质无关的准确且精确的硼同位素比值。这种方法在地球化学中开辟了广泛的应用领域，包括生物源碳酸盐中的pH值重建以及解读与流体-矿物相互作用相关的过程。
