Extraction of humic acids and their fractions in poly(ethylene glycol)-based aqueous biphasic systems |
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Authors: | AG Zavarzina VV DeminTI Nifant’eva VM ShkinevTV Danilova BYa Spivakov |
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Institution: | a Soil Science Department, Moscow State University, 119899 Moscow, Russia b Institute of Soil Science MSU-RAS, 119899, Moscow, Russia c Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin str., 117975 Moscow, Russia |
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Abstract: | The possibility of extraction and fractionation of humic acid (HA) in the aqueous biphasic systems (ABS) was shown for the first time. The 10% PEG-10% (NH4)2SO4-H2O and 5% PEG-7.5% dextran (or dextran sulphate, sodium salt)-H2O systems were used. HA originated from peat, soddy-podzolic soil and chernozem were studied. The distribution coefficients were measured for HA of different origin, size of the molecules, molecular weights (MW) of the polymers and pH of the system. The PEG-(NH4)2SO4-H2O system was found to be better for preconcentration and isolation of HA, whereas the PEG-dextran-H2O system is preferable for HA fractionation. The extractability of HA in ABS increases with increasing the MW of HA molecules. Peat HA are extracted in ABS with higher distribution coefficients compared with chernozem and soddy-podzolic soil HA. It is consistent with higher hydrophobicity of peat HA revealed by hydrophobic interaction chromatography. ABS are promising for HA separation into fractions that differ in their hydrophobic/hydrophilic properties as well as for comparing HA of different origin by their relative hydrophobicity. |
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Keywords: | Humic acids Aqueous biphasic systems Fractionation Membrane filtration Gel permeation chromatography |
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