Enantiomerization and enantioselective bioaccumulation of diclofop-methyl in tubifex worms

In this study, the hydrolysis of diclofop-methyl (DM) in aqueous system and the bioaccumulation of its main metabolite, Diclofop (DA), in the tubifex worms were investigated using enantioselective high-performance liquid chromatography. With the addition of tubifex, rapid hydrolysis was observed for DM. It is revealed that the hydrolysis of DM in the water and the accumulation of DA in the worms were both enantioselective. Meanwhile, either the hydrolysis amount or the levels of enantioselectivity were influenced by the tubifex. After incubated for 24 h, about 94.6% of the DM was hydrolyzed and the enantiomer fraction of metabolite (DA) deviated from 0.5 with R-DA significantly higher than S-DA. The enantiopure S-DM and R-DM and S-DA and R-DA were incubated, and enantiomerizations were detected between the two DM enantiomers with S-form inversing into R-form and vice versa. It was found that the S-DM exhibited a higher tendency to invert than the R-DM.