EVALUATION OF THE BINDING MECHANISM OF ANILAZINE AND ITS METABOLITES IN SOIL ORGANIC-MATTER

Soil bound residues of organic xenobiotics or their metabolites can be partly extracted by diluted NaOH together with the humic and fulvic acids or remain in the humin. These residues, however, are only detected by their radioactivity after using C-14- or H-3-labeled xenobiotics. A more detailed analysis of the binding character of xenobiotics was conducted with the fungicide Dyrene(R) which contains anilazine as an active ingredient. This compound forms up to 80% of unextractable residues after a short incubation period in soil. C-13 NMR-spectroscopic analysis of the bound residues in the humic matrix of a soil could be significantly improved by application of the C-13-enriched ingredient. Further improvement was gained by incubation of the fungicide in an artificial soil, obtained by humification from corn stalk material of plants previously grown in a (CO2)-C-12 atmosphere. The results revealed that the binding of anilazine metabolites occurs in the form of ethers or possibly also of esters with various functional OH-groups of the humic molecules. Derivatization of the humus matrix by silylating reagents also provided additional information.