Enantioseletive bioaccumulation and metabolization of diniconazole in earthworms (Eiseniafetida) in an artificial soil

• A chiral liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the analysis of diniconazole enantiomers in earthworms and soil sample matrixes.
• Three levels of exposure concentrations (1 mg/kg, 10 mg/kg and 25 mg/kg) in soil (dry weight) to earthworms were investigated to study the degradation and bioaccumulation.
• Enantioseletive bioaccumulation was observed in the earthworm. The bioaccumulation factors (BAF) of R, S isomers were 6.6046 and 8.5115 in 25 mg/kg dose exposure, 2.6409 and 2.9835 in 10 mg/kg dose exposure, 1.7784 and 2.0437 in 1 mg/kg dose exposure, respectively. S-diniconazole was with a preferential accumulation and enantiomer fractions were about 0.52–0.55 in all three level dose exposures.
• Diniconazole was metabolized to 1, 2, 4-triazole, (E)-3-(1H-1,2,4-triazol-1-yl)acrylaldehyde, (E,S)-4-(2,4-dichlorophenyl)-2,2-dimethyl-5-(1H-1,2,4-triazol-1-yl)pent-4-ene-1,3-diol, and (E)-4-(2,4-dichlorophenyl)-3-hydroxy-2,2-dimethyl-5-(1H-1,2,4-triazol-1-yl)pent-4-enoic acid in earthworms.

Degradation and enantioselective bioaccumulation of diniconazole in earthworms (Eiseniafetida) in artificial soil was investigated using liquid chromatography–tandem mass spectrometry (LC–MS/MS) method under laboratory condition. Three exposure concentrations (1 mg/kg, 10 mg/kg and 25 mg/kg) of diniconazole in soil (dry weight) to earthworms were used. The uptake kinetics fitted the first-order kinetics well. The bioaccumulation factors (BAF) of R, S isomers were 6.6046 and 8.5115 in 25 mg/kg dose exposure, 2.6409 and 2.9835 in 10 mg/kg dose exposure, 1.7784 and 2.0437 in 1 mg/kg dose exposure, respectively. Bioaccumulation of diniconazole in earthworm tissues was enantioselective with a preferential accumulation of S-diniconazole and the enantiomer fractions were about 0.45–0.50 in all three level dose exposures. In addition, it was obvious that both R-diniconazole and S-diniconazole had bioaccumulation effect in earthworm. Diniconazole was metabolized to 1,2,4-triazole, (E)-3-(1H-1,2,4-triazol-1-yl) acrylaldehyde, (E, S)-4-(2, 4-dichlorophenyl)-2, 2-dimethyl-5-(1H-1,2,4-triazol-1-yl)pent-4-ene-1,3-diol, and (E)-4-(2, 4-dichlorophenyl)-3-hydroxy-2,2-dimethyl-5-(1H-1,2,4-triazol-1-yl) pent-4-enoic acid in earthworms; the metabolites of 1,2,4-triazole and (E)-3-(1H-1,2,4-triazol-1-yl)acrylaldehyde could be detected in soil as well.