Derivatization of Humic Compounds: An Analytical Approach for Bound Organic Residues |
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Authors: | K Haider M Spiteller K Reichert M Fild |
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Institution: | 1. Institut für Pflanzenern?hrung u. Bodenkunde, BFA-Landwirtschaft (FAL) , D-3300, Braunschweig, Bundesallee 50;2. Bayer AG, Crop Protection Research, Chemical Product Development and Environmental Biology , D-5090, Leverkusen-Bayerwerk;3. Institut für Anorganische u. Analytische Chemie, Technische Universit?t Braunschweig , D-3300, Braunschweig, Hagenring 30 |
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Abstract: | Abstract Bound residues of pesticides and their metabolites are defined as being nonextractable with organic solvents, but partly extractable together with the humic matrix by NaOH or other solvents suitable to extract humic compounds. Recently, an improvement in humus extraction from soils was achieved upon derivatization of the organic matter with silylating reagents at room temperature. By this method 70–90% of the organic carbon or nitrogen either from soil or from humin became soluble in organic solvents. The extracts were analyzed by means of 13C NMR-spectroscopy. The spectra were well resolved with signal-separation of less than 1 ppm. The extracted humic compounds were of rather low molecular weight, ranging from 300 to 4000 to 6000 d or more. 14C-labeled residues of pesticides or other xenobiotics found to be nonextractable after exhaustive organic solvent extraction became readily dissolved along with most of the humic matrix using this derivatization procedure. Between 60–80% of 14C anilazine residues or of 14C-labeled chlorinated phenols or anilines originating from both previously solvent extracted soil samples or from humin became solubilized in organic solvents. |
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Keywords: | Soil humus derivatization with silylating reagents 13C NMR-spectroscopy 14C-labeled pesticides bound pesticide residues extraction upon silylation |
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