Dissolved organic matter (DOM) of aquatic systems, a diverse, complex mixture of water-soluble biogenic and anthropogenic organic compounds, constitutes one of the largest exchangeable organic carbon pools on the planet and is involved in numerous biogeochemical cycles. Although DOM characterization is challenging due to its high heterogeneity, a holistic comprehension of DOM composition is crucial to assess the health status of the ecosystem. Here, non-target liquid chromatography high-resolution mass spectrometry (LC-HRMS) was combined with novel computational tools to achieve a comprehensive data analysis workflow that allows, for the first time, an in-silico characterization of DOM at a molecular structural level. This computational workflow enabled structural annotation of 10% of the almost 20,000 molecular features detected from the analysis of three water samples (sea, river and drinking water). The LC and the prospect of DOM structural characterization enhance the understanding of the DOM pool, especially if combined with the more traditional direct infusion (DI) HRMS approach. With DI, thousands of molecular formulas were assigned, but the technique is still limited by issues such as signal suppression of multiple interfering analytes and the lacking possibility of detecting isomers or obtaining structural information. Moreover, the LC approach expands the domain of analysed DOM towards the less polar fraction of compounds. In conclusion, the combination of non-target analyses with computational MS provides new insights into DOM composition.

Primary Presenter: Jessica Patrone, Institute of Environmental Assessment and Water Research (IDAEA-CSIC) (jessica.patrone@cid.csic.es)

Authors:

Jessica Patrone, Institute of Environmental Assessment and Water Research (IDAEA-CSIC)  (jessica.patrone@cid.csic.es)

Maria Vila-Costa, Institute of Environmental Assessment and Water Research (IDAEA-CSIC)  ()

Jordi Dachs, Institute of Environmental Assessment and Water Research (IDAEA-CSIC)  ()

Stefano Papazian, Department of Environmental Science (ACES), Stockholm University  ()

Pablo Gago Ferrero, Institute of Environmental Assessment and Water Research (IDAEA-CSIC)  ()

Rubén Gil Solsona, Institute of Environmental Assessment and Water Research (IDAEA-CSIC)  ()