Acid pyrophosphate extraction of soil fulvic acids |
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Authors: | J E GREGOR H K J POWELL |
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Institution: | Chemistry Department, University of Canterbury. Christchurch. New Zealand |
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Abstract: | A simple three step method is described for isolation of soil fulvic acids in high yield. The complexing agent H2P2O72? (at pH 2) is used to release soil-bound fulvic acids. Extraction of humic acids is minimal. Selective separation of the protonated fulvic acids from the ionic extractant is achieved on a non-ionic polyacrylate resin (Amberlite XAD-7); after washing the resin, fulvic acids were retrieved in >98% yield by adjusting the pH to 6.5. Two problems associated with the classical alkali extraction method are avoided: possible alkaline oxidation of phenolic components, and their oxidation by Fe3+ under the acidic conditions employed to precipitate humic acids. The product typically has an ash weight of <0.6% after one XAD treatment. The method has been applied to three soils and one IHSS peat sample. |
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