BIOMIMETIC OXIDATION OF PLANT PROTECTING AGENTS

The suitability of two in vitro oxidation systems as chemical models f or the biological degradation of plant protecting agents has been inve stigated. As representative herbicides diclofop, fenoxaprop, isoprotur on, linuron and monolinuron have been oxidised by two systems, the Fen tons' reagent and the ascorbic acid oxidation system (AAOS) and the re sults compared to those of the known metabolic pathways of these compo unds. The herbicides have been oxidised by Fentons' reagent (hydroxy r adicals). The main products were isolated by preparative scale HPLC an d identified with H-1-NMR and MS. Some of the products have been ident ified by comparing their retention times and UV/Vis-spectra to those o f standard compounds. Several products known from biological degradati on are also found after chemical oxidation, however, notable differenc es between the two pathways have been observed, for instance in the ca se of diclofop. Oxidation by the AAOS leads to comparable results. Rea ction rates for the oxidation with the AAOS have been studied and comp ared with data known from degradation studies of the herbicides in soi l. Compounds which are slowly degraded in soil are oxidised more slowl y in the biomimetic process than those with a fast degradation in soil .