USING C-13-NMR SPECTROSCOPY TO EVALUATE THE BINDING MECHANISM OF BOUND PESTICIDE-RESIDUES IN SOILS .1. SOLUTION HIGH-RESOLUTION NMR-SPECTROSCOPY

Soil-bound residues of organochemicals and their metabolites can be extracted together with the humic acid fraction. These residues are only detectable by using radioactive labelling, e.g. C-14 (or H-3). An analysis of the character of the bonding can be achieved by means of C-13-NMR spectroscopy. A prerequisite is a C-13-enrichment of the observed molecule and, if possible, a C-13-depletion of the humic substances. The fungicide anilazine is known to form high amounts of soil-bound residues within a few days. C-13-NMR spectra of extracted humic acids of two different orthic luvisols (Parabraunerde), a gleyic cambisol (Pseudogley Braunerde) and of an artificially prepared soil from humified, C-13-depleted maize straw show ester or ether bonds of anilazine to the humic acids. Line broadening of less than or equal to 20 Hz yields a group of signals which indicate that different functional groups of the humic acids are responsible for the bondings.