Online Liquid Chromatography and FT-ICR MS Enable Advanced Separation and Profiling of Organosulfates in Dissolved Organic Matter

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.

Automated summary

Dissolved organic matter (DOM) is a complex mixture of organic compounds at the land/ocean-atmosphere interface. Utilizing Fourier transform ion cyclotron resonance mass spectrometry with liquid chromatography can effectively analyze and characterize various compounds in DOM, providing insights into their potential sources and reaction mechanisms.