A. Wais et al., USING C-13-NMR SPECTROSCOPY TO EVALUATE THE BINDING MECHANISM OF BOUND PESTICIDE-RESIDUES IN SOILS .1. SOLUTION HIGH-RESOLUTION NMR-SPECTROSCOPY, Journal of environmental science and health. Part B. Pesticides, food contaminants, and agricultural wastes, 30(1), 1995, pp. 1-25
Soil-bound residues of organochemicals and their metabolites can be ex
tracted together with the humic acid fraction. These residues are only
detectable by using radioactive labelling, e.g. C-14 (or H-3). An ana
lysis 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 re
sidues within a few days. C-13-NMR spectra of extracted humic acids of
two different orthic luvisols (Parabraunerde), a gleyic cambisol (Pse
udogley Braunerde) and of an artificially prepared soil from humified,
C-13-depleted maize straw show ester or ether bonds of anilazine to t
he 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.