A new method combining online nano solid phase extraction coupled with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was developed to extract and analyze organic matter (OM) from microliter volumes of salt containing soil solution samples. This approach allows the reproducible analysis of only minute amounts of organic carbon (down to 10 ng C) without the need of further sample preparation. The new method was applied to unravel developing small-scale patterns of dissolved organic matter (DOM) in soil solutions of a soil column experiment in which Zea mays plants were grown for 3 weeks. Soil solution was sampled by micro suction cups from the undisturbed soil-root system once a week. Growth of the root system and, hence, position of individual roots relative to the suction cups was followed by X-ray computed tomography (X-ray CT). Our method makes it possible to resolve the chemical complexity of soil solution OM (up to 4300 molecular formulas from 2.5 μL sample). This allows to observe chemical gradients in the rhizosphere on a molecular level over time. The increasing influence of roots on soil solution OM is visible from higher molecular masses, an increasing degree of oxygenation and a higher fraction of formulas containing heteroatoms. The online nano solid phase extraction-FT-ICR-MS method provides novel insight into the processes affecting DOM in the rhizosphere, such as root exudation, microbial processes, and soil organic matter stabilization.

中文翻译：

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在线纳米固相萃取傅里叶变换离子回旋共振质谱工作流程，以分析根际土壤溶液有机物的小规模梯度。

开发了一种在线纳米固相萃取与傅立叶变换离子回旋共振质谱（FT-ICR-MS）相结合的新方法，用于从微升体积的含盐土壤溶液样品中萃取和分析有机物（OM）。这种方法只需要可重现的微量有机碳分析（低至10 ng C），而无需进一步的样品制备。该新方法被用于解开在玉米中可能发生的土壤柱试验的土壤溶液中小规模溶解有机物（DOM）模式的开发。植物生长3周。每周一次用微型吸盘从原状土壤-根系中取样土壤溶液。X射线计算机断层扫描（X射线CT）跟踪根系的生长以及各个根相对于吸盘的位置。我们的方法可以解决土壤溶液OM的化学复杂性（从2.5μL样品中提取多达4300个分子式）。这样可以观察到随着时间分子水平在根际中的化学梯度。从较高的分子量，较高的氧合度和较高比例的含杂原子的配方中可以看出，根对土壤溶液OM的影响越来越大。在线纳米固相萃取-FT-ICR-MS方法提供了新颖的见解，以了解影响根际中DOM的过程，例如根系渗出，