Interaction of aquatic dissolved organic matter (DOM) with amitrole : The nature of the bound residues

In this study the binding behaviour of the herbicide amitrole with humic substances respectively dissolved organic matter (DOM) is presented. The results of the binding and release experiments using radioactively 14C-labelled amitrole led to the conclusion that the binding of amitrole is very low. About 70% of amitrole bound to humic substances was not extractable. The releasable amitrole portion of the purified DOM-amitrole complexes led to a harmful effect in the cress test. Solid-state cross polarisation (CP) magic angle spinning (MAS) 15N-NMR spectroscopy is a powerful spectroscopic method to elucidate the structure ofbound xenobiotics. In addition extraction experiments were used resulting in a binding scheme of amitrole to DOM, where above all the covalent bonding occurred via acid amide bonds.