A STRUCTURAL STUDY OF ALKYL POLYMERS IN SOIL AFTER PERBORATE DEGRADATION OF HUMIN

A structural study on the humic material insoluble in acid and alkali solutions-soil humin fraction-was carried out in three representative types of humus. After the exhaustive removal of free and aggregated plant residues, humic acids, fulvic acids and insolubilized humic colloids, the remaining organic matter was subjected to seven successive mild treatments with sodium perborate. By this method, the humin was transformed into alkali-soluble macromolecular substances in addition to low MW compounds. The former material was studied mainly by non-destructive techniques usual in humic acid studies, whereas the latter was analyzed by gas chromatography-mass spectrometry. The results revealed well-defined biopolymer patterns, the predominant constituents having poly-alkyl structures. The typical monomer units of cutins and suberins were identified, but the presence of additional lipid and aromatic material from different origins was also discussed. Some characteristic microbial products were also found, including fungal polynuclear pigments in two of the samples studied. Additional amounts of lignin-related structures and polypeptide material were present in the humins studied.