Simultaneous Elucidation of the Chemodiversity of Dissolved Organic Matter and Quantitation of Trace Organic Contaminant Sucralose by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has become a cutting-edge technique for molecular characterization of dissolved organic matter (DOM) and trace organic contaminants. Nevertheless, FT-ICR MS is rarely applied to simultaneously elucidate DOM chemodiversity and quantify the concentrations of trace organic contaminants. Compared to conventional solid-phase extraction (SPE), pH-dependent fractionation of DOM molecules using a sequential SPE strategy significantly enhanced the recovery of dissolved organic carbon and yielded more chemical formulas for DOM from environmental samples (<i>p</i> < 0.05). The sequential SPE at circumneutral pH provided exclusive isolation of some hydrogen-rich and oxygen-poor molecules, caused a 5-fold reduction in matrix effects, and improved the detection limits for organic contaminants. The chemical structure of a typical wastewater indicator, sucralose, was successfully validated using FT-ICR MS analysis with tandem mass spectrometry and hydrogen/deuterium exchange measurements. With the standard addition method, the limits of detection and quantitation of FT-ICR MS for sucralose in DOM extracts isolated at circumneutral pH were estimated to be 0.26 and 0.87 μg/L, respectively. The concentrations of sucralose in a representative urban lake measured by FT-ICR MS (e.g., 0.9-4.1 μg/L) were comparable to those determined by liquid chromatography coupled to an Orbitrap mass analyzer. The findings of this study expand application of FT-ICR MS in environmental research by highlighting its potential for identifying trace organic contaminants, quantifying their concentrations, and elucidating the chemodiversity of DOM to inform contaminant sources in aquatic systems.