STRUCTURAL INVESTIGATIONS OF HUMIC SUBSTANCES BY IR-FT, C-13-NMR SPECTROSCOPY AND COMPARISON WITH A MALEIC OLIGOMER OF KNOWN STRUCTURE

Humic and fulvic acids isolated from an Italian Typic Dystrochrept by conventional means have been investigated by spectroscopic techniques (IR-FT, C-13-NMR). A quantitative C-13-NMR technique was applied. The investigated fulvic acid contains more aliphatic than aromatic moieties. The carboxyl contents of fulvic acid are greater than those of humic acid. In comparison with fulvic acid the humic acid has a higher content of aromatics. The data presented indicate that structural units resembling those of polymaleic acid may be present in fulvic acid but similar structures have not been detected in humic acid.