Quizalofop-P-ethyl
In the soil environment Quizalofop-P-ethyl degrades to the main degradate Quizalofop-acid by hydrolysis of the ester. Further hydrolysis of the side chain occurs resulting Quizalofop-phenol. Hydroxylation of the quinoxaline ring occurs to give 3-OH-Quizalofop-acid. Cleavage of the ether linkage leads to the formation of series of degradates containing either the quinoxaline ring or phenyl ring. Both series of degradates are further degradated to CO2. Quizalofop-acid has been identified in all of the studies with the maximum percentage formed ranging from 67 % to 84 %. The occurrence of other main metabolites 3-OH-Quizalofop-acid and 3-OH-CQO has been found to be lower ranging from 10 % to 16 %. Four minor metabolites have been identified on occasions, Quizalofopphenol, 6-Chloroquinoxaline-2-one (CQO), Ethyl-2-(4-hydroxyphenoxy)propionate (EPP) and PPA at maximum percentages of <5 %. The amounts of carbon dioxide ranged from 2.6 to 35 % of the applied radioactivity by the end of the study. Unextracted soil bound residues accounted for between 23 % and 48 % of the applied Quizalofop-P-ethyl at the end of the studies. In addition to investigations with Quizalofop-P-ethyl (R(+) enantiomer), the behaviour of the racemate (R/S)- Quizalofop-ethyl and S(-)-Quizalofop-ethyl has been studied. The dominant enantiomeric conversion was from the S(-)-Quizalofop-acid to the R(+) enantiomer.