Different Enantioselective Degradation of Pyraclofos in Soils

Abstract

This study investigated the enantioselective degradation behavior of pyraclofos in three soils (NC, HZ, and ZZ) under native and sterilized conditions. The absolute configuration of pyraclofos enantiomers has been determined by the combination of experimental and calculated electronic circular dichroism spectra. S-(+)- and R-(-)-Pyraclofos were separated and determined on a cellulose tri-(4-chloro-3-methylphenylcarbamate) (Lux Cellulose-4) chiral column by reversed-phase high-performance liquid chromatography-tandem mass spectrometry. Pyraclofos enantiomers were configurationally stable in three soils and no interconversion was observed during the incubation of enantiopure S-(+)- or R-(-)-pyraclofos under native conditions. The enantioselective degradation behavior of chiral pyraclofos was dramatically different in three soils under native conditions, with half-lives (t(1/2)) of pyraclofos in NC, HZ, and ZZ soils of 2.6, 13.4, and 7.8 days for S-(+)-pyraclofos and 9.2, 9.3, and 8.2 days for R-(-)-pyraclofos. Compared to the half-lives (t(1/2)) of rac-pyraclofos of 21.5, 55.9, and 14.4 days in sterilized NC, HZ and ZZ soils, the degradation velocity was greatly improved in native soils, indicating that degradation was greatly attributed to microbially mediated processes in agricultural cultivating soils.

Enantioseparation and enantioselective behavior of trichlorfon enantiomers in sediments

“…The MEs for R ‐(−)‐TF, S ‐(+)‐TF, and DDVP were 0.97, 0.95, and 0.96, respectively (Table ). These values are less than 0.05, indicative of a negligible matrix effect from the sediment . The LODs were observed to be 0.031, 0.040, and 0.013 μg/g for R ‐(−)‐TF, S ‐(+)‐TF, and DDVP, respectively, in the sediment samples.…”

Validation of a Chiral Liquid Chromatographic Method for the Degradation Behavior of Flumequine Enantiomers in Mariculture Pond Water

“…The minimum geometries were fully optimized at the B3LYP/6‐311G (d) level of theory in the gas phase to yield more accurate conformers. The ECD spectra were simulated at the B3LYP/6‐311G (d, p) level of theory in methanol . The calculated ECD curves were generated using SpecDis with a σ of 0.2 eV.…”

“…The degradation behavior of FLU enantiomers in mariculture pond water was investigated under natural, sterile, and dark conditions using the developed method. Since the absolute configuration of enantiomers is an important parameter for understanding the biochemical properties of chiral compounds, the absolute configurations of FLU enantiomers were determined by comparing the experimental and calculated electronic circular dichroism (ECD) spectra …”

“…9 Enantiomers of some chiral compounds, including antibiotics, exhibit different biological activities including toxicity and effects on organisms and the environment. [10][11][12][13] The degradation and metabolic products of such compounds may also be chiral and typically differ in their chemical and toxicological properties, as compared to the parent compounds. As such, they may exhibit various ecological risks.…”

Simultaneous determination of florfenicol with its metabolite based on modified quick, easy, cheap, effective, rugged, and safe sample pretreatment and evaluation of their degradation behavior in agricultural soils

“…Separate incubation experiments with florfenicol and florfenicol amine in soils were conducted using 50 mL polypropylene centrifuge tubes covered with aluminum foil . Approximately 5.0 g of soil (dry weight equivalent) was fortified with 25 μg (50 μL of a 500 μg/mL stock solution in acetone) of florfenicol or florfenicol amine and they were set to air‐dry for 5 min before being homogenized thoroughly (experiments NC f and NC fa for Nanchang soil; HZ f and HZ fa for Hangzhou soil; CC f and CC fa , for Changchun soil).…”