| Abstract: | A method is described for the determination of residues of fenazaflor (I), its hydrolysis product 5,6-dichloro-2-trifluoromethylbenzimidazole (II) and the metabolite 5,6-dichloro-4-hydroxy-2-trifluoromethylbenzimidazole (III) in apples and pears. These chemicals may be present in the crop as a result of the application of the acaricide fenazaflor, formulated as a wettable powder and known by the trade name ‘Lovozal’. Total residues of I and II are determined as II, and III is determined after methylation, both by GLC with electron capture detection. The limit of detection for each compound is 0.02parts/million (based on a 50 g sample weight). Recoveries are over 80%. Using apples sprayed with radio-labelled fenazaflor it was shown that approximately 20% of the total radioactivity present in the fruit was not extracted by the routine method. Further investigation showed much of this to be present as trifluoroacetic acid in a tightly bound form. No problems were encountered with interference from a number of commonly used orchard pesticides. |
