Isotopic exchange ultrahigh resolution mass spectrometry is a powerful tool for investigation of molecular structure of Dissolved Organic Matter

摘要

We report that isotopic exchange approach coupled to ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR MS) is the powerful tool for chemical and structural characterization of the individual molecules of Dissolved Organic Matter (DOM). In the present work we used in-ESI source Hydrogen/Deuterium (H/D) exchange for enumeration of acidic and hydroxyl hydrogens, acid catalyzed ~(16) O/ ~(18) O exchange for enumeration of labile oxygens and acid catalyzed H/D exchange for determination of labile back-bone hydrogens. We identified number of labile hydrogens in 450 individual molecules and number both of labile hydrogens and oxygens in 231 molecules composing DOM. Also we observed that several back-bone hydrogen atoms can be exchanged for deuterium under acidic conditions.