Distribution behaviour of acaricide cyflumetofen in tomato during home canning

Fate characteristics and risk quantification of cyflumetofen from tomato cultivation to processing based on large-scale applications

Elucidating the fate characteristics of cyflumetofen and its main metabolite 2-TFMBA in tomato from cultivation to processing is crucial for safeguarding the environment and humans from hazardous effects. Cyflumetofen and 2-TFMBA could exist stably in tomato matrices for at least 343 days under frozen and dark conditions according to UHPLC-MS/MS, with a limit of quantitation of 0.001 mg/kg and retention time within 2.12 min. The occurrence, dissipation, and concentration variation of cyflumetofen were reflected by original depositions of 0.02-0.44 mg/kg, half-lives of 1.7-7.2 days, and terminal magnitudes of 0.005-0.30 mg/kg, respectively, with various influencing factors, e.g., climate conditions and tomato cultivars. Additionally, 13.5-59.3% of cyflumetofen was metabolized to 2-TFMBA, showing significant toxicological effects ranging from cultivation to processing. When the concentration decreased by 0.06 mg/kg, cyflumetofen was effectively removed by peeling, while washing was the recommended method for removing 2-TFMBA with a processing factor of 0.70. The comparative dietary risks of sum cyflumetofen were assessed for all life cycle populations using deterministic and probabilistic models. The risk quotients decreased to 1.3-4.8 times during the preparation of home canning tomato paste. Despite the low exposure risk, the potential health hazards of sum cyflumetofen should be considered, given its ubiquity and cumulative effects.

Determination of etoxazole in different parts of citrus fruit and its potential dietary exposure risk assessment

In this study, the profile of etoxazole in whole citrus, peel and pulp samples collected from Chongqing, Guangdong and Anhui provinces was monitored and their dietary risk to human had also been assessed. The final residual levels and distributions of etoxazole in citrus samples were detected by using an ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The results showed that final concentrations of etoxazole in whole citrus, peel, and pulp were ranged at 0.012-0.174, 0.010-0.637, and 0.010-0.011 mg kg^-1, respectively. The assessment of dietary risk suggested that chronic dietary risk of etoxazole in whole fruit and peel were 0.010-0.197% and 0.035-0.951%, respectively. Our findings indicated that the chronic risk of daily consumption of citrus fruit is acceptable at recommended dosage.

Removal residues of pesticides in apricot, peach and orange processed and dietary exposure assessment

The effects of the industrial processing are evaluated of the removal of 16 pesticide residues in canned apricots and peaches and in orange juice. A method of multi-residual extraction that uses QuEChERS and liquid chromatography in tandem with triple quadrupole mass spectrometry was used. The method shows good linearity for the 16 pesticides studied (R2 > 0.999); it is accurate and precise (recoveries of 87-115%, relative standard deviation <8.0%). The processing factors are <0.6, indicating that all the processes significantly reduce the residue levels (spinosad, thiacloprid, pyridaben, bupirimate, flusilazole, triflumizole, flonicamid, imidacloprid, lambda-cyhalothrin, cyproconazole, fludioxinil and cyprodinil, abamectin, chlorpyrifos-methyl, hexythiazox and metalaxyl) initially present in the raw fruits and very significantly during washing/cutting, squeezing and hot pack canning (>55% loss). The risk quotient (EDI/ADI ratio) for canned foods is below 100, indicating that the potential consumer risk for the pesticides studied is practically negligent for human health.

Analysis of the Physicochemical Properties of Acaricides Based on Lipinski's Rule of Five

This study aimed to explore the similarity between the physical and chemical properties of different acaricides, determine whether Lipinski's Rule of Five (RO5) used in the design of drug molecules is suitable for screening acaricides, and provide methods for selection of new acaricides. We evaluated and predicted the molecular properties of >180 acaricides using Molinspiration. We calculated physicochemical property parameters, such as log p, molecular weight (MW), and number of hydrogen bond donors (HBDs), hydrogen bond acceptors (HBAs), and rotatable bonds (Rot B). We then conducted qualitative and quantitative analyses of the physicochemical properties of acaricides. The MW of all acaricides ranged from 141 to 663, with an average value of 337.8. The number of HBDs ranged from 0 to 5, with an average value of 0.46. The number of HBAs ranged from 0 to 9, with an average value of 4.07. The log p ranged from -0.79 to 8.74, with an average value of 4.61. The number of Rot B ranged from 0 to 14, with an average value of 5.62. Except for the microbial and plant-derived acaricides, the molecular properties of the remaining acaricides are in accordance with the Lipinski's RO5. Therefore, the Lipinski's RO5 can provide a basis for screening new acaricide drugs.

Preparation of cyflumetofen nanocapsules and study on the controlled release performance and its field efficacy

BACKGROUND

In this study, 5% cyflumetofen nanocapsules were prepared by interfacial polymerization with isophorone diisocyanate and polyethylene glycol as the reaction monomer, and tristyrylphenol polyoxyethylene ether (601-P) as the emulsifier. The physical, chemical and sustained release properties of cyflumetofen nanocapsules were characterized using scanning electron microscopy, field emission scanning electron microscopy, laser particle size analysis, Fourier transform infrared spectroscopy, contact angles testing and high-performance liquid chromatography.

RESULTS

The results indicated that cyflumetofen nanocapsules were spherical, with an average particle size of 100 nm, and an encapsulation efficiency and loading rate of 86% and 32%, respectively. The thermal and cold storage stabilities of cyflumetofen nanocapsules were good. Under high temperature, lower pH or a high core-wall ratio, nanoparticle release is faster. The field efficacy experiment indicated that the efficacy of cyflumetofen nanocapsules against Panonychus citri reached 97%, 30 days after spraying, significantly greater than that of a 20% cyflumetofen suspension.

CONCLUSION

It is important to increase the stability, lengthen the release period and improve the efficacy of cyflumetofen in cyflumetofen nanocapsules. © 2018 Society of Chemical Industry.

The dissipation of thiamethoxam and its main metabolite clothianidin during strawberry growth and jam-making process

Few studies focused on the residue of thiamethoxam and its metabolite clothianidin on strawberry where it is widely used, despite this is essential to assess the potential food risk of thiamethoxam and its main metabolite clothianidin. In this study, the dissipation of thiamethoxam and its metabolite clothianidin during strawberry growth and jam-making process were assessed. The strawberry was sprayed with thiamethoxam based on the field application to investigate the dissipation of thiamethoxam as well as clothianidin formation. The half-life of thiamethoxam in strawberry was 9.0 days and the concentration of clothianidin in strawberry gradually increased from 0.55 to 11 μg/kg within 30 days. In addition, the amount of thiamethoxam decreased by 51.7% and clothianidin decreased by 40.2% during the homogenization process. The processing factor values of whole processing all less than 1 except simmering. This results from this study will not only help to understand the dissipation kinetics of thiamethoxam and clothianidin in the strawberry, but also facilitate to make more accurate risk assessments of them during strawberry jam making process.

Residue and Dietary Risk Assessment of Chiral Cyflumetofen in Apple

Ultra-performance convergence chromatography is an environmentally-friendly analytical method that uses dramatically reduced amounts of organic solvents. In addition, a robust and highly sensitive chiral separation method was developed for the novel chiral acaricide cyflumetofen by using ultra-performance convergence chromatography coupled with tandem mass spectrometry, which shows that stereoisomer recoveries determined for various apple parts ranged from 78.3% to 119.9%, with the relative standard deviations being lower than 14.0%. The half-lives of (−)-cyflumetofen and (+)-cyflumetofen obtained under 5-fold applied dosage equal to 22.13 and 22.23 days, respectively. For 1.5-fold applied dosage, the respective values were determined as 22.42 and 23.64 days, i.e., the degradation of (−)-cyflumetofen was insignificantly favored over that of its enantiomer. Importantly, cyflumetofen was unevenly distributed in apples, with its relative contents in apple peel, peduncle, and pomace equal to 50%, 22%, and 16%, respectively. The proposed method can be used to efficiently separate and quantify chiral pesticide with advantages of a shorter analysis time, greater sensitivity, and better environmental compatibility. Additionally, the consumption of apples with residue of cyflumetofen did not pose a health risk to the population if the cyflumetofen applied under satisfactory agricultural practices after the long-term dietary risk assessment.