Molecular Characterization of the Water-Soluble Organic Compounds in Fogwater by ESIMS/MS

Abstract

Water-soluble organic compounds (WSOC) often represent a large fraction of the total organic mass found in the atmospheric aerosol. They play a very important role in determining the ability of aerosol particles to act as cloud condensation nuclei (CCN), influencing cloud and fog formation and cloud albedo. Molecular characterization of WSOC in fogwater samples was achieved using a two-stage ion-trap mass spectrometer equipped with electrospray ionization (ESIMS/MS). Negative ionization conditions in the electrospray interface finalized our characterization of the acidic fraction of WSOC that comprises both mono- and di-carboxylic acids and polycarboxylic acids for which a similarity was suggested with naturally occurring humic (or fulvic) acids, and which are sometimes referred to in the literature as humic-like substances (HULIS). Molecular structure elucidation was accomplished using several model compounds and exploiting mass spectral resolution for compound separation. Single compound identification ...