RESUMEN
Pesticide residues are currently a prominent concern for food safety, and the development of a rapid, convenient, and accurate method for detecting pesticide residues is crucial to ensure the quality of agricultural products. In this study, a small molecule fluorescent probe based on biphenyl disulfonic acid (BDSA) was designed and prepared, and a sensitive, specific, and rapid detection method for diquat (DQ) and paraquat (PQ) was developed. The fluorescent molecule (BDSA-NDA) was synthesized through amide reaction between BDSA and 1,8-naphthalic anhydride, which exhibited cyan fluorescence (480 nm) when excited at 305 nm in aqueous solution with a large Stokes shift (>150 nm). Diquat and paraquat were found to quench the fluorescence of the probe through internal filtration effect (IFE) and photoelectron transfer (PET). Moreover, diquat possessed a large conjugated structure that emitted fluorescence at 340 nm which was assembled into a pair of ratio fluorescence with BDSA-NDA. Under optimized experimental conditions, the developed method achieved detection limits of 0.003 mg/L for diquat and 0.202 mg/L for paraquat. Furthermore, it could identify paraquat doped in diquat formulations. Additionally, when applied to environmental water samples as well as rice and urine, this detection method demonstrated good recovery rates (water: 96.2-100.6 %, rice: 93.5-101.9 %, urine: 96-103.7 %), meeting actual sample detection requirements effectively. This work presents a novel approach for rapidly detecting diquat and paraquat residues which holds practical application value in areas such as pesticide residue analysis in foods, environmental or clinical samples.
RESUMEN
The residue of mulch film is a crucial source of microplastics (MPs) in agricultural fields. The effects of mulch film-derived MPs on the environmental behavior of pesticides in agriculture remain unclear. In the present study, the effects of MPs of different sizes (5 mm, 1 mm, 30 µm, and 0.3 µm) at environmentally relevant concentrations on pesticide transport were evaluated, and the mechanism was explored with respect to adsorption and pore structure using fluorescence visualization, the extended Derjaguin-Landau-Verwey-Overbeek model, and microcomputed tomography. MPs were found to be retained in the soil due to size limitation, pore capture, and surface adhesion. The presence of mm-sized MPs (5 and 1 mm) at a concentration of 0.25 % inhibited the leaching behavior of atrazine, metolachlor, and tebuconazole. MPs did not significantly alter the pesticide adsorption ability of the soil. The reduced leaching originated from the impact of MPs on soil pore structure. Specifically, the porosity increased by 16.2-25.0 %, and the connectivity decreased by 34.5 %. These results demonstrate that mm-sized MPs inhibit pesticide leaching by obstructing the pores and altering the transport pathways, thereby potentially elevating environmental risks, particularly to the soil ecosystem.
RESUMEN
Sulfoxaflor is a widely used fourth-generation neonicotinoid pesticide, which has been detected in biological and environmental samples. Sulfoxaflor can potentially be exposed to humans via the food chain, thus understanding its toxic effects and enantioselective bioaccumulation is crucial. In this study, toxicokinetics, bioaccumulation, tissue distribution and enantiomeric profiles of sulfoxaflor in rats were investigated through single oral exposure and 28-days continuous exposure experiment. Sulfoxaflor mainly accumulated in liver and kidney, and the (-)-2R,3R-sulfoxaflor and (-)-2S,3R-sulfoxaflor had higher enrichment than their enantiomers in rats. The toxicological effects were evaluated after 28-days exposure. Slight inflammation in liver and kidney were observed by histopathology. Sphingolipid, amino acid, and vitamin B6 metabolism pathways were significantly disturbed in metabonomics analysis. These toxicities were in compliance with dose-dependent effects. These results improve understanding of enantioselective bioaccumulation and the potential health risk of sulfoxaflor.
