A comparison of the structural characteristics of polymaleic acid and a soil fulvic acid

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Abstract
Summary: The purpose of this investigation was to compare structural characteristics of PMA with those of FA in order to assess the suitability of PMA to serve as a model for FA. Chemical (elemental analyses, CO2H group determinations, increases in OCH3 after methylation, oxidative degradation) and spectroscopic (visible, UV, fluorescence, IR, 13CNMR, and ESR) methods were used for this purpose. While PMA was found to resemble FA in a number of characteristics (water solubility, rich in CO2H groups, dark brown colour), it significantly differed from FA in a number of respects (UV, fluorescence, 13CNMR spectra as well in oxidation products). Compared to FA, PMA appeared to be better organized and more homogeneous at the molecular level, richer in olefinic structures and less aromatic. But the chemical structures of both PMA and FA remain largely unknown.