Dissolved organic matter (DOM) is an ultracomplex mixture of organic compounds in the land/ocean–atmosphere interface. Normally, polar compounds from DOM are hardly retained by liquid chromatography (LC) columns for further analytical purposes. Here, we utilized Fourier transform ion cyclotron resonance mass spectrometry with LC for online analysis of DOM in river water and rainwater. With sophisticated instrumental optimization, different portions of metal salts, carboxyl-rich alicyclic molecules, organosulfates (OSs), and lignin-like compounds could be fully fractionated within one LC cycle (20 min). The complexity of the analyte was greatly reduced by LC separation, which therefore allows much better MS performance. Moreover, the compounds’ structures were characterized by tandem mass spectrometry (MSⁿ). The protocol presented herein offers a novel insight into the conventional LC-MS method, that it has the potential to investigate OSs and other components in DOM according to specific functional groups and heteroatoms and to explore their potential sources and reaction mechanisms.

中文翻译：

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在线液相色谱和 FT-ICR MS 能够对溶解有机物中的有机硫酸盐进行高级分离和分析

溶解有机物 (DOM) 是陆地/海洋-大气界面中有机化合物的超复杂混合物。通常，用于进一步分析的液相色谱 (LC) 柱很难保留来自 DOM 的极性化合物。在这里，我们利用傅里叶变换离子回旋共振质谱和 LC 在线分析河水和雨水中的 DOM。通过精密的仪器优化，金属盐的不同部分、富含羧基的脂环族分子、有机硫酸盐 (OS) 和木质素类化合物可以在一个 LC 循环（20 分钟）内完全分馏。LC 分离大大降低了分析物的复杂性，从而获得了更好的 MS 性能。此外，化合物的结构通过串联质谱（MS ⁿ）。本文提出的协议提供了对传统 LC-MS 方法的新见解，它有可能根据特定的官能团和杂原子研究 DOM 中的 OS 和其他成分，并探索它们的潜在来源和反应机制。