Saurer Matthias, Oettli Manuela, Lehmann Marco M
Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland.
Rapid Commun Mass Spectrom. 2025 Feb 28;39(4):e9957. doi: 10.1002/rcm.9957.
Determining several isotope ratios in one analysis multiplies the information that can be retrieved from a sample in a cost-efficient way. The stable isotope ratios of hydrogen (δH), carbon (δC), and oxygen (δO) in organic compounds are highly relevant due to their complimentary hydroclimatic and physiological signals. Different types of organic material reflect different processes and integration times, like short term in leaf sugars and long term in tree ring cellulose, but currently, no simple method exists for their triple isotope analysis.
Here, we present a method that enables the isotopic analyses of the three elements H, C, and O in one run and is applicable to different types of carbohydrates and bulk organic matter. We discuss all steps required from water vapor equilibration necessary for obtaining reliable δH values of carbon-bound H to high-temperature conversion (HTC) of the sample to CO and H and to the mass-spectrometric isotope-ratio analysis.
We show that reliable triple isotope analysis is possible for a large range of samples, although it results in some reduction of precision compared to individual isotope analysis. Important considerations are the equilibration procedure, the type of autosampler, selection of HTC reactor, the influence of nitrogen in the sample, the verification of δC values obtained by HTC versus combustion, and the selection of reference materials.
By presenting a relatively simple triple-isotope method, we promote the use of multi-isotope studies in environmental sciences, which helps in addressing many important climate and ecological research challenges that we face today.
在一次分析中测定多种同位素比率，能以经济高效的方式增加从样品中获取的信息。有机化合物中氢（δH）、碳（δC）和氧（δO）的稳定同位素比率因其互补的水文气候和生理信号而具有高度相关性。不同类型的有机物质反映不同的过程和整合时间，例如叶糖中的短期过程和树木年轮纤维素中的长期过程，但目前尚不存在用于它们的三重同位素分析的简单方法。
在此，我们提出一种方法，该方法能够在一次运行中对氢、碳和氧这三种元素进行同位素分析，并且适用于不同类型的碳水化合物和大量有机物质。我们讨论了从获得与碳结合的氢的可靠δH值所需的水汽平衡到样品高温转化（HTC）为一氧化碳和氢气以及质谱同位素比率分析所需的所有步骤。
我们表明，对于大量样品进行可靠的三重同位素分析是可行的，尽管与单个同位素分析相比，其精度会有所降低。重要的考虑因素包括平衡程序、自动进样器类型、HTC反应器的选择、样品中氮的影响、通过HTC与燃烧获得的δC值验证以及参考材料的选择。
通过提出一种相对简单的三重同位素方法，我们推动了环境科学中多同位素研究的应用，这有助于应对我们当今面临的许多重要气候和生态研究挑战。
