Mass spectrometry of humic substances of different origin including those from Antarctica

133Cs and 35Cl NMR spectroscopy and molecular dynamics modeling of Cs+ and Cl− complexation with natural organic matter

“…The TNB model also has 2 amine groups, while the Steelink model has only one. The molecular weight of the TNB model is 753 Daltons, which is within the range of the most frequently occurring NOM molecules (Simpson et al, 2002;Peñ a-Méndez et al, 2005).…”

“…Whether NOM molecules are single macromolecular entities or supramolecular assemblages of smaller molecules held together by relatively weak attractive forces is still under discussion (Swift, 1999;Wershaw, 1999;Haynes and Clapp, 2001;Piccolo, 2001;Leenheer and Croué, 2003). The most recent experimental evidence seems to support the latter view (Simpson et al, 2002;Peñ a-Méndez et al, 2005). These uncertainties contribute to the difficulty in characterizing metal-NOM binding in molecular-scale detail.…”

Molecular Scale Modeling of Membrane Water Treatment Processes

“…There is even discussion [109][110][111][112][113] in the literature as to whether humic substances are true macromolecules or supramolecular structures formed from smaller subunits and held together via relatively weak noncovalent interactions, with soil scientists modeling humic acids via the latter scenario [114][115][116], while water chemists consider the former model [112]. In this regard, there is no singular identifiable ''humic acid molecule''; rather, several structural models have been developed, which contain well-defined functional groups as determined by experimental analysis.…”

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF–MS) coupled to XAD fractionation: Method to algal organic matter characterization

“…In MALDI, a protecting matrix is used to induce soft ionization due to the absorption of a large part of the laser energy by the matrix [13]. The mass spectra of Humic Substances are dominated by low molecular weight ions (usually between 500 and 3000 m/z ratio) [13][14][15][16]. According to the theory of supramolecular aggregates, individual components with low molecular weights (500-1500 Da) are bound by non-covalent bonds to form humic acid and fulvic acid [17].…”