CHEMICAL CHARACTERIZATION OF PEAT FULVIC-ACID FRACTIONS

Milled peat fulvic acid (FA) preparation was fractionated by XAD-8 and conventional extraction methods. The fractions were further analyzed by IR and NMR and subjected to cupric oxide (CuO) oxidation. Carbohydrates of polydisperse FA were mostly not retained in the XAD-8 fractionation. The intensity of the signals due to double bonded carbons was much greater in the C-13 and proton NMR spectrum of the XAD-8 retained fraction than in the spectra of the XAD-8 non-retained or XAD-8 non-treated fractions. In CuO oxidation the main products of all FA fractions were 4-hydroxybenzaldehyde and 4-hydroxyacetophenone, both indicators of 4-hydroxyphenylpropane building blocks. Their concentrations by weight of the fractions were greatest in the XAD-8 retained fraction and smallest in the non-retained fraction. The amounts of the aromatics were so low, however, that aromaticity can explain only part of the unsaturation shown by the NMR spectra. The existence of olefinic double bonds in the fulvic acid structure is a possibility that should be studied.