Effects of Eluate Drying on the Chemodiversity of Dissolved Organic Matter Revealed by Ultrahigh-Resolution Mass Spectrometry

The drying treatment of dissolved organic matter (DOM) eluate was often used to prepare DOM solutions for chemodiversity analysis using Fourier transform ion cyclotron resonance mass spectrometry. However, the effects of drying treatment on the chemodiversity of DOM have not been thoroughly investigated. In this study, vacuum freeze-drying and vacuum centrifuge drying resulted in approximately half and 10% loss of DOM mass loss, respectively. Although the overall values of molecular functional diversity indices and main DOM fractions were insignificantly affected by both drying treatments, the Cl-containing molecules (Cl-OM) and saturated compounds were significantly affected by the drying treatments, particularly for vacuum centrifuge drying. Therefore, the DOM eluate was strongly recommended for the measurement of Fourier transform ion cyclotron resonance mass spectrometry only after dilution by desired folds when the minor DOM fractions, such as Cl-OM and saturated compounds, were of interest. The findings of this study have provided valuable evidence of sample preparation for the accurate elucidation of DOM chemodiversity from various sources.