Photodegradation of insecticide metofluthrin on soil, clay minerals and glass surfaces

Photodegradation of pyrethroid insecticide metofluthrin (I) [2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (EZ)-(1R,3R)-2,2-dimethyl-3-(prop-I-enyl)cyclopropanecarboxylate] on soil, clay minerals, and glass surfaces was examined using a xenon arc lamp (>290 nm). I was rapidly photodegraded via oxidation of the double bond at the prop-1-enyl moiety and cleavage of the ester linkage followed by mineralization to carbon dioxide, while photoisomerization to other isomers was a minor route. The major photodegradates having an intact ester linkage were the caronaldehyde and carboxylic acid derivatives formed via 1,2,4-trioxolane (ozonide) and the diol derivatives formed via epoxide, which strongly suggested the involvement of ozone and hydrogen peroxide as the active oxygen species. C Pesticide Science Society of Japan