Dissipation and residues of dimethyl disulfide in tomatoes and soil under greenhouse and open field conditions

Dissipation, Processing Factors and Dietary Risk Assessment for Flupyradifurone Residues in Ginseng

The massive use of pesticides has brought great risks to food and environmental safety. It is necessary to develop reliable analytical methods and evaluate risks through monitoring studies. Here, a method was used for the simultaneous determination of flupyradifurone (FPF) and its two metabolites in fresh ginseng, dried ginseng, ginseng plants, and soil. The method exhibited good accuracy (recoveries of 72.8–97.5%) and precision (relative standard deviations of 1.1–8.5%). The field experiments demonstrated that FPF had half-lives of 4.5–7.9 d and 10.0–16.9 d in ginseng plants and soil, respectively. The concentrations of total terminal residues in soil, ginseng plants, dried ginseng, and ginseng were less than 0.516, 2.623, 2.363, and 0.641 mg/kg, respectively. Based on these results, the soil environmental risk assessment shows that the environmental risk of FPF to soil organisms is acceptable. The processing factors for FPF residues in ginseng were 3.82–4.59, indicating that the concentration of residues increased in ginseng after drying. A dietary risk assessment showed that the risk of FPF residues from long-term and short-term dietary exposures to global consumers were 0.1–0.4% and 12.07–13.16%, respectively, indicating that the application of FPF to ginseng at the recommended dose does not pose a significant risk to consumers.

Pesticide-Residue Analysis in Soils by the QuEChERS Method: A Review

Pesticides are among the most important contaminants worldwide due to their wide use, persistence, and toxicity. Their presence in soils is not only important from an environmental point of view, but also for food safety issues, since such residues can migrate from soils to food. However, soils are extremely complex matrices, which present a challenge to any analytical chemist, since the extraction of a wide range of compounds with diverse physicochemical properties, such as pesticides, at trace levels is not an easy task. In this context, the QuEChERS method (standing for quick, easy, cheap, effective, rugged, and safe) has become one of the most green and sustainable alternatives in this field due to its inherent advantages, such as fast sample preparation, the minimal use of hazardous reagents and solvents, simplicity, and low cost. This review is aimed at providing a critical revision of the most relevant modifications of the QuEChERS method (including the extraction and clean-up steps of the method) for pesticide-residue analysis in soils.

2-Hydroxypropyl-β-cyclodextrin encapsulates dimethyl disulfide producing a controlled release formulation

Dimethyl disulfide (DMDS), a soil fumigant, is an effective, broad-spectrum compound that often replaces bromomethane (MB) in the prevention and treatment of soil-borne diseases. However, the disadvantages of DMDS include toxicity, volatility, pungent odor, risk of human exposure, and environmental pollution. Cyclodextrin (CD) has been widely used as a carrier of chemicals in many industries due to its functional advantages and safety. In this study, a DMDS-controlled release formulation was developed by encapsulating DMDS in the cavity of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). This formulation reduced DMDS usage and production costs. Orthogonal experimental design, Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM), Thermal gravity analysis (TGA) characterization, efficacy comparison, safety, and other aspects of the evaluation showed that under the best preparation conditions, the encapsulation rate was 81.49%. The efficacy of DMDS@HP-β-CD was similar to unformulated DMDS. The efficacy duration of the formulation was about two times longer than DMDS, and it was safer to use. This study reveals a cyclodextrin-DMDS formulation with reduced toxicity, longer duration, environmental safety and sustainability.

Determination of the Novel Insecticide Flupyradifurone and Its Two Metabolites in Traditional Chinese Herbal Medicines Using Modified QuEChERS and High-Performance Liquid Chromatography-Tandem Mass Spectrometry

In this study, an analytical method for the simultaneous determination of the novel insecticide flupyradifurone and its two metabolites in a variety of traditional Chinese herbal medicines was developed for the first time using high-performance liquid chromatography-tandem mass spectrometry. A simple and efficient method using dispersive solid-phase extraction was employed for the pretreatment of the samples. Several extractions and cleanup strategies were evaluated. The recoveries (n = 15) of flupyradifurone and its metabolites at three spiking levels were in the range 71.3%-101.7%, with corresponding intraday and interday relative standard deviations of 1.1%-14.8%. The limits of quantitation were 0.01 mg/kg for flupyradifurone and 0.1 mg/kg for its two metabolites. Overall, our developed method was sensitive and reliable for the fast screening of flupyradifurone and its two metabolites in traditional Chinese herbal medicine samples.