Seawater Analysis by TM-DART-QTOF-MS-Based Metabolomics

NICOLAS ZABALEGUI; HAYECK, NATHALIE; VAN PINXTEREN, MANUELA; MONGE, MARIA EUGENIA; DEPOORTER, ANTOINE; LI, CHUNLIN; GEORGE, CHRISTIAN; M MANZI; ROVERETTO, MARIE; HERRMANN, HARTMUT

Conferencia Virtual

Conferencia; 16th Annual Conference of the Metabolomics Society; 2020

The Metabolomics Society

The chemical composition of the ocean surface influences physicochemical processes at the air-water interface. The sea surface microlayer (SML) covers up to 70 % of the Earth?s surface and is enriched in dissolved organic matter. An improved chemical characterization of the SML would increase the current understanding of its contribution to atmospheric composition, air quality and climate change. Sea surface microlayer (SML) and underlying water (ULW) samples (n=22, 10 paired samples) were collected during a field campaign at the Cabo Verde islands to investigate their chemical composition. A transmission mode direct analysis in real-time quadrupole time-of-flight mass spectrometry (TM-DART-QTOF-MS)-based untargeted metabolomics method coupled with multivariate statistical analysis, addressed as seaomics, allowed the analysis of lipophilic compounds in seawater samples with no need of desalination. A panel of 11 ionic species was capable of differentiating samples according to their collection depth (i.e., SML or ULW). Tentative identification of discriminant species enriched at SML samples based on accurate masses, isotopic patterns, and fragmentation pattern analyses from TM-DART-QTOF-MS/MS experiments, suggested that fatty alcohols, halogenated organic compounds, and oxygenated boron-containing organic compounds may be available at the ocean surface for water-air transfer processes. In addition, a subset of SML samples (n = 5) was subjected to on-site experiments during the field campaign to test whether they were photochemically active and evaluate their secondary organic aerosol formation efficiency by means of a lab-to-field approach. Results illustrate the capabilities of this combined approach to analyze organic compounds involved in aerosol formation processes at the water/air interface.