Imidacloprid has become a research hotspot, due to its high toxicity to bees and other nontarget organisms. Photodegradation is a common method for removing imidacloprid in an aquatic environment. Traditional methods of pesticide photodegradation have generally been confined by many factors, such as response to only high-energy ultraviolet light. Herein, the visible-light-driven photocatalyst graphitic carbon nitride (g-C3N4) was applied to the photodegradation of imidacloprid. Visible-light illumination (λ >400 nm) resulted in nearly 90% substrate transformation in 5 h. With the illumination of an energy-saving lamp, imidacloprid has also been mostly removed. 1-((6-chloropyridin-3-yl)methylhydroxy)imidazolidin-2-ylidene nitramide) and 4,5-dihydro-N-nitro-1-(3-pyridinylmethyl)-1H-imidazol-2-amine were the main photoproducts identified by LC-MS analysis. The photocatalytic mechanism has also been discussed. This work could provide new perspective that g-C3N4, as a good visible-light photocatalyst could be applied to the cleanup of environmental pesticide pollution.

Unique graphitic carbon nitride (g-C3N4) nanovessels have been prepared and applied as solid phase extraction (SPE) adsorbent for determining benzoylurea pesticides (BUs) in different juice samples using high performance liquid chromatography (HPLC) equipped with ultraviolet detection (UVD). The g-C3N4 nanovessels were obtained on a large scale by thermally converting low-cost urea without additive assistance, which avoided a complex synthesis process, consumption of organic solvent, and limits of tailoring the reaction pressure and atmosphere. The g-C3N4 nanovessels have been characterized using transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, and elemental analysis. The conditions affecting the extraction efficiency were optimized, including adsorbent amount, extraction time, sample volume, and choice and volume of desorption solvent. Under the optimal conditions, comparable detection limits of 6 μg/L and good recoveries of 70.4–96.4 % for six BUs have been achieved. Meanwhile, g-C3N4 nanovessels showed excellent reuse potential for ten times. The results indicated that g-C3N4 nanovessels repesented a promising SPE adsorbent for the enrichment and trace analysis of pollutants.

Fenoxaprop-P-ethyl is widely applied in rice ecosystem for weeding. A simple and accurate method for determination of fenoxaprop-P-ethyl and its metabolite fenoxaprop-P in paddy water, paddy soil, rice plants, husked rice, straw and rice hull was established by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS). Recoveries of fenoxaprop-P-ethyl and fenoxaprop-P in these matrices at three spiking levels ranged from 75.1 to 102.8% with relative standard deviations (RSDs) of 1.6 to 8.2%. The limits of detection (LODs) of fenoxaprop-P-ethyl and fenoxaprop-P were 0.003 mg/kg. Fenoxaprop-P-ethyl dissipated rapidly to fenoxaprop-P in paddy water and soil during hours. The half-life of fenoxaprop-P-ethyl in rice plants was 1.26–1.41 days, and the half-life of fenoxaprop-P in paddy water, paddy soil and rice plants was 1.87–1.93, 1.61–2.31 and 1.82–1.93 days. The ultimate residues of fenoxaprop-P-ethyl and fenoxaprop-P in paddy soil, straw, rice hull and husked rice samples at harvest were not detectable or below 0.01 mg/kg.

Residual fluazinam in the environment may cause dermatitis and occupational asthma. Therefore, it is important to determine the dissipation behavior of fluazinam in edible raw food and in the environment. The aim of this study was to monitor a fungicide fluazinam on potato. A method for the analysis of fluazinam residue and its dissipation in potato plants and soil under field conditions was studied. Fluazinam residues were analyzed using a modified Quick, Easy, Cheap,Effective, Rugged, and Safe (QuEChERS) method and gas chromatography coupled with electron capture detector (GC-ECD). Mean recoveries and relative standard deviations (RSD) in potato plants, potatoes, and soil at three spiking levels were 85.1–99.5 and 0.7–2.8 %, respectively. The limits of quantification (LOQ) were 0.01 mg kg−1 for all three matrices. The dissipation dynamics of fluazinam were investigated in field trials in Hebei and Anhui provinces. In potato plants, fluazinam had a half-life of 2.5 days in Hebei and 3.6 days in Anhui. The half-life of fluazinam in soil was 4.7 days in Hebei and 13 days in Anhui. Terminal residues in soil samples ranged from 0.0925 to 0.949 mg · kg−1 and fluazinam was not detected in potato at pre-harvest intervals of five, seven, and 10 days. It was safe for fluazinam application on potato according to the recommended dosage and times.Fluazinam residual en el ambiente pudiera causar dermatitis y asma ocupacional. De aquíque es importante determinar el comportamiento de disipación de fluazinam en alimentoscrudos y en el ambiente. El propósito de este estudio fue monitorear un fungicida fluazinamen papa. Se estudió un método para el análisis de residuos de fluazinam y su disipación enplantas de papa y en suelo bajo condiciones de campo. Se analizaron los residuos defluazinam utilizando un método modificado rápido, fácil, barato, efectivo, robusto y seguro(QuEChERS) y cromatografía de gas acoplada con un detector de captura de electrones(GCECD). Las medias de las recuperaciones y las desviaciones estándar relativas (RSD) enplantas de papa, tubérculos y suelo a tres niveles de detección fueron de 85.1--99.5 y 0.7--2.8 % respectivamente. Los límites de cuantificación (LOQ) fueron 0.01 mg kg−1 para lastres matrices. Se investigaron las dinámicas de disipación de fluazinam en ensayos decampo en las provincias de Hebei y Anhui. En las plantas de papa fluazinam tuvo una vidamedia de 2.5 días en Hebei y de 3.6 días en Anhui. En el suelo la vida media del productofue de 4.7 días en Hebei y de 13 días en Anhui. Los residuos terminales en las muestras delsuelo fluctuaron de 0.0925 a 0.949 mg kg−1 y no se detectó fualzinam en tubérculos aintervalos de pre-cosecha de cinco, siete y diez días. Fue segura la aplicación de fluazinamen papa de acuerdo a la dosis y tiempos recomendados.

Graphene, a novel class of carbon nanostructure, possesses an ultra-high specific surface area (theoretical value 2,630 m2 g−1), and both sides of the planar sheets of graphene are available for molecule adsorption. Graphene has already been used for preconcentration, extraction, and electrochemical selective determination. In this study, we used graphene to clean up pigments in cucumber for analysis, and measured eight pyrethroid model analytes using GC with electron capture detection (ECD). The recoveries of the 8 pyrethroids were 75–116 % with RSDs below 10 %, and LOQs ranged from 2.5 to 10 μg kg−1. Comparative studies showed that graphene was superior to graphitized carbon black for the purification of pigments. We also investigated the ability of graphene to clean up spinach. A promising new adsorbent for pesticide residue analysis was developed. Graphene has significant potential as an effective adsorbent of pigments.

Residue dynamics of thiacloprid in cabbage and soil was studied in this paper utilizing liquid chromatography with tandem mass spectrometry (LC–MS/MS). The field trial was conducted in two sites: Beijing, China and Hubei, China. Thiacloprid dissipated rapidly with the half-life 1.3–1.6 days in cabbage and 2.1–3.1 days in soil. In the terminal residue experiment, no higher residue than 0.06 mg/kg in cabbage and 0.16 mg/kg in soil was detected, which was far below either EU MRL (0.2 mg/kg) or Japan MRL (1 mg/kg).

•We examine cotransport of bismerthiazol and montmorillonite colloids in sand.•Transport of bismerthiazol is facilitated by copresence of montmorillonite colloids.•Transport of montmorillonite colloids is concurrently enhanced by bismerthiazol.•The colloids can change the reversibility of contaminant's association with collector.•Changing colloid shape can change colloid deposition mechanism.While bismerthiazol [N,N′-methylene-bis-(2-amino-5-mercapto-1,3,4-thiadiazole)] is one of the most widely used bactericides, the transport of bismerthiazol in subsurface environments is unclear to date. Moreover, natural colloids are ubiquitous in the subsurface environments. The cotransport of bismerthiazol and natural colloids has not been investigated. This study conducted laboratory column experiments to examine the transport of bismerthiazol in saturated sand porous media both in the absence and presence of montmorillonite colloids. Results show that a fraction of bismerthiazol was retained in sand and the retention was higher at pH 7 than at pH 4 and 10. The retention did not change with ionic strength. The retention was attributed to the complex of bismerthiazol with metals/metal oxides on sand surfaces through ligand exchange. The transport of bismerthiazol was enhanced with montmorillonite colloids copresent in the solutions and, concurrently, the transport of montmorillonite colloids was facilitated by the bismerthiazol. The transport of montmorillonite colloids was enhanced likely because the bismerthiazol and the colloids competed for the attachment/adsorption sites on collector surfaces and the presence of bismerthiazol changed the Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction energies between colloids and collectors. The transport of bismerthiazol was inhibited if montmorillonite colloids were pre-deposited in sand because bismerthiazol could adsorb onto the colloid surfaces. The adsorbed bismerthiazol could be co-remobilized with the colloids from primary minima by decreasing ionic strength. Whereas colloid-facilitated transport of pesticides has been emphasized, our study implies that transport of colloids could also be facilitated by the presence of pesticides.