Isoelectric focusing of soil humic substances in the presence of 8Murea

摘要

The isoelectric focusing (IEF) of different-molecular-size humic fractions, either separately or recombined, was carried out in the presence and absence of 8Murea. In the presence of urea, the fractions were recognizable from both their characteristic microheterogeneity and ranges of focalization. Urea caused a slight shift of the bands towards lower pH values. The refocusing of characteristic band of one fraction produced a slight discrepancy in the isoelectric points (0.2–0.3 pH units). However, the maintenance of the banding in 8Murea and the homogeneity of the band under refocusing demonstrated the reliability of the IEF in fractionating structurally different humic substances. Such experiments should provide useful information on the association/dissociation properties of soil organic matter under controlled condition