From Water to Water: Insight into the Translocation of Pesticides from Plant Rhizosphere Solution to Leaf Guttation and the Associated Ecological Risks.

Plant guttation is an important source of water/nutrients for many beneficial insects, while the presence of pesticides in guttation has been considered as a new exposure route for nontarget insects. This study aimed to elucidate how 15 diverse pesticides are translocated from growth media to guttation by maize plants through a hydroponic experiment. All pesticides were effectively translocated from the growth solution to maize guttation and reached a steady state within 5 days. The strong positive correlation (R2 = 0.43-0.84) between the concentrations of pesticides in guttation and in xylem sap demonstrated that xylem sap was a major source of pesticides in guttation. The relationship between the bioaccumulation of pesticides in guttation (BCFguttation) and the chemical Kow was split into two distinct patterns: for pesticides with log Kow > 3, we identified a good negative linear correlation between log BCFguttation and log Kow (R2 = 0.71); however, for pesticides with log Kow < 3, all data fall close to a horizontal line of BCFguttation ≅ 1, indicating that hydrophilic pesticides can easily pass through the plants from rhizosphere solution to leaf guttation and reach saturation status. Besides, after feeding with pesticide-contaminated guttation, the mortality of honeybees was significantly impacted, even at very low levels (e.g., ∑600 µg/L with a mortality of 93%). Our results provide essential information for predicting the contamination of plant guttation with pesticides and associated ecological risks.

Pesticides in Greenhouse Airborne Particulate Matter: Occurrence, Distribution, Transformation Products, and Potential Human Exposure Risks.

Pesticides are frequently sprayed in greenhouses to ensure crop yields, where airborne particulate matter (PM) may serve as a carrier in depositing and transporting pesticides. However, little is known about the occurrence and fate of PM-borne pesticides in greenhouses. Herein, we examined the distribution, dissipation, and transformation of six commonly used pesticides (imidacloprid, acetamiprid, prochloraz, triadimefon, hexaconazole, and tebuconazole) in greenhouse PM (PM1, PM2.5, and PM10) after application as well as the associated human exposure risks via inhalation. During 35 days of experiment, the six pesticides were detected in all PM samples, and exhibited size- and time-dependent distribution characteristics, with the majority of them (>64.6%) accumulated in PM1. About 1.0-16.4% of initially measured pesticides in PM remained after 35 days, and a total of 12 major transformation products were elucidated, with six of them newly identified. The inhalation of PM could be an important route of human exposure to pesticides in the greenhouse, where the estimated average daily human inhalation dose (ADDinh) of the six individual pesticides was 2.1-1.2 × 104 pg/kg day-1 after application (1-35 days). Our findings highlight the occurrence of pesticides/transformation products in greenhouse PM, and their potential inhalation risks should be further concerned.

Dissipation dynamics and comparative dietary exposure assessment of mefentrifluconazole in rice.

A fast and sensitive analytical method based on UHPLC coupled with tandem mass spectrometry was established to investigate the dissipation and final residual amounts of mefentrifluconazole in rice, and dietary risk to consumers was evaluated. The method provided good linearity (R2 ≥ 0.9979), accuracy (recovery range, 79.0-101.5%), precision (relative standard deviation range, 1.3-13.9%), and sensitivity (limit of quantification, 0.005 mg/kg). The dissipation dynamics of mefentrifluconazole in rice followed first-order kinetics, with half-lives of 2.8-16.6 days. The final residues of mefentrifluconazole in various samples of harvested brown rice ranged from less than the limit of quantification to 0.092 mg/kg, the latter value being higher than the maximum residue limit recommended by the European Union. Comparative dietary exposure of mefentrifluconazole was assessed using field data and Chinese dietary patterns for different genders, regions, and age data. Although the results showed acceptable levels of risk for both acute exposure (the percentage of the acute reference dose ≤ 0.7483%) and chronic dietary intake (the percentage of acceptable daily intake ≤ 31.8516%), more studies of children are needed because they are at higher risk than other groups. This work provides the necessary data for registering and establishing the maximum residue limit for mefentrifluconazole in rice in China and reveals the potential risks to different groups of long-term application of mefentrifluconazole to rice and other crops.

Highly-Selective Analytical Strategy for 90 Pesticides and Metabolites Residues in Fish and Shrimp Samples.

The analysis of pesticide residues in aquatic products is challenging due to low residue levels and the complex matrix interference. In this study, we developed a simple, fast method for the trace analysis of 90 pesticides and metabolites in aquatic products. The analytes covered a wide polarity range with log Kow (log octanol-water partition coefficient) ranging from -1.2 to 6.37. Grass carp (Ctenopharyngodon idellus) and prawn (Penaeus chinensis) samples were chosen to validate the quantification method. The samples were extracted by 0.2% formic-acetonitrile, cleaned by solid-phase extraction (PRiME HLB), and analyzed by high performance liquid chromatography-tandem mass spectrometry. The results showed good linearities for the analytes and were observed in the range of 0.05-50 µg/L. The recoveries of the method were within 50.4-118.6%, with the relative standard deviations being lower than 20%. The limits of quantifications (LOQs) of the method were in the range of 0.05-5.0 µg/kg, which were superior to values compared with other research. The developed method was applied to detect pesticide residues in prawn samples from eastern coastal areas of China. Three herbicide residues of diuron, prometryn, and atrazine were detected in prawn samples. The method was sensitive and efficient, which is of significance in expanding the screening scope and improving the quantitative analysis efficiency in aquatic products.

Occurrence and impact of carbendazim and hymexazol residues on yeast growth and ochratoxin A contamination during wine production.

BACKGROUND: Grapes are highly vulnerable to infection by carbon black aspergilli, which produce ochratoxin A (OTA), a mycotoxin. Carbendazim and hymexazol are widely applied to control grape diseases. Howerver, fungicides, toxigenic fungi, and OTA can be transferred from grapes to wine causing potential safety issues. The impact of these residues on fungal populations and OTA during vinification are currently unclear. Here we investigated the effects of carbendazim and hymexazol on the viability of Aspergillus carbonarius and OTA contamination during an indoor wine-processing experiment. RESULTS: The population size of A. carbonarius substantially increased at 24 h followed by a significantly decreased at 72 h after destemming and crushing. However, carbendazim and hymexazol notably inhibited the growth of A. carbonarius in must samples. In addition, yeast growth was substantially deleyed by carbendazim, hymexazol, and OTA during the first 3 days in compared with the control. Carbendazim, hymexazol, and OTA residues declined over time, and the processing factors (PFs) for carbendazim and hymexazol throughout vinification were 0.164, 0.074, and 0.185-0.476, respectively. Carbendazim and hymexazol each reduced OTA concentrations. However, there was no significant difference after 48 h. Addition of carbendazim or hymexazol significantly reduced the level of A. carbonarius but had no significant effect on the final concentration of OTA in mature wine. CONCLUSION: The wine-making process can reduce the residues of OTA, carbendazim, and hymexazol in grapes, but it is recommended that grapes chosen to make wine should be free of A. carbonarius contamination. © 2023 Society of Chemical Industry.

Trace determination of imidacloprid and its major metabolites in wheat-soil system.

Trace analysis method is a reliable basis for studying the translocation and metabolism of imidacloprid used as an insecticide in wheat, and it clarifies whether biologically active metabolites including residual imidacloprid, have long-lasting insecticidal potency against wheat aphids under seed treatment during the entire growth period. In this study, a highly sensitive analytical method was established to determine the residues of imidacloprid and its six metabolites (5-hydroxy imidacloprid, imidacloprid olefin, imidacloprid guanidine, imidacloprid urea, 6-chloronicotinic acid, and imidacloprid nitrosimine) in wheat-soil systems, such as in wheat leaves, wheat ears, wheat grains, roots, and soil. All the compounds were extracted using an ACN:water (8:2, v/v) mixture and purified by dispersive solid-phase extraction. The average recoveries ranged from 74.4% to 109.5% for all matrices, with intra- and inter-day variations of less than 14.9%. The limit of quantitation was in the range of 0.001-0.005 mg/kg. The method is demonstrated to be sensitive and accurate for monitoring imidacloprid and its metabolites at trace levels during the entire growth period under field conditions.

Residual levels of five pesticides in peanut oil processing and chips frying.

BACKGROUND: Pesticide contamination in oil crops and processed products is an important food safety concern. The study was aimed to investigate the pesticide residue changes in press processing of peanut oil and frying of chips. RESULTS: Five pesticides - chlorpyrifos, deltamethrin, methoxyfenozide, azoxystrobin and propargite - which are often applied during growth period in peanut plants, were selected to investigate their residue changes in cold press processing of peanut oil and frying of potato chips. Results showed that the residues of the five pesticides were decreased by 3.1-42.6% during air-drying before oil pressing. The residues of chlorpyrifos, deltamethrin, methoxyfenozide and propargite in peanut oil were 2.05-3.63 times higher than that in peanut meal after cold pressing of the oil, except for azoxystrobin having a slightly lower residue in peanut oil, with 0.92 times that in peanut meal. The processing factors of the five pesticides in peanut oil ranged from 1.17 to 2.73 and were highly related to the log Kow of the pesticides. The higher the log Kow , the more easily was the pesticide partitioned in the peanut oil. Besides, as frying time increase during preparation of chips, the concentration of pesticides in peanut oil decreased gradually by 6.7-22.1% compared to the first frying. In addition, 0.47-11.06% of the pesticides were transferred to the chips through frying with contaminated oil. CONCLUSION: This is first report showing that pesticides can transfer from contaminated oil to chips. There exists a potential dietary health risk by using pesticide-contaminated oil for frying chips. This work could provide basic data for accurate dietary risk assessment of pesticide residues in peanut oil and its frying products. © 2021 Society of Chemical Industry.

Enantioselective fate of famoxadone during processing of apple cider and grape wine.

Famoxadone enantiomers were separated on Lux Amylose-1 chiral column and determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The half-lives of R-(-)-famoxadone and S-(+)-famoxadone were 69.3 and 86.6 h in apple cider, 231.0 and 346.5 h in apple pomace, 69.3 and 77.0 h in grape wine, and 231.0 and 346.5 h in grape pomace, respectively. The enantiomeric fraction (EF) values decreased gradually from 0.498, 0.499, and 0.500 (0 h) to 0.404, 0.374, and 0.427 (144 h) and then increased gradually to 0.474, 0.427, and 0.422 (312 h) in apple cider, grape wine, and grape pomace. The EF value in apple pomace decreased gradually from 0.499 (0 h) to 0.450 (168 h) and then increased gradually to 0.482 (312 h). The processing factors (PFs) for famoxadone ranged from 0.014 to 0.024 in the overall process. The residue of famoxadone reduced 94.7-97.4% after the fermentation process.

Quantitative determination of pyriproxyfen and its metabolite residues in bee products of China using a modified QuEChERS approach with UPLC-MS/MS.

Given the key role of bees as indicators for environmental assessment, residues in bees and bee products have attracted great interest. In this regard, an improved, highly sensitive method for quantifying the insecticide pyriproxyfen and its four metabolites (4'-OH-Pyr, DPH-Pyr, 2-OH-PY, 4'-OH-POP) in honeybees, larvae, and bee products (honey, pollen, royal jelly and wax) should be established. For this purpose, we used ultra-performance liquid chromatography coupled with triple-quadrupole mass spectrometry for rapid quantification (≤5 min). Recoveries for various matrices ranged from 73.77% to 114.97%, with satisfactory intra-day and inter-day precision (relative standard deviations of 0.03-8.61% and 0.10-7.25%, respectively). The results demonstrated excellent linearity (R2 > 0.9903) with a limit of quantification of 1 µg/kg for six different matrices. We collected and analyzed 597 samples (honey, bees and wax) from four major beekeeping areas in China. Only 47 of these samples contained residues of pyriproxyfen and two of its metabolites (2-OH-PY, 4'-OH-Pyr), and high levels of contamination were found in bee samples (2-739 µg/kg), with substantive accumulation in wax (levels were 9.49% higher than in other samples). The result demonstrate that the method provides a reliable and convenient means of monitoring pyriproxyfen and its metabolites in bee products for better product quality, human health, and international commercial competition and also lays a foundation for risk assessment of potential pyriproxyfen contamination in China.

Monitoring the behavior of imazalil and its metabolite in grapes, apples, and the processing of fruit wine at enantiomeric level.

BACKGROUND: Imazalil is widely used in agriculture, which may pose a threat to food safety. This study aimed to investigate the fate of imazalil and its main metabolite, R14821 (imazalil-M), in field grapes and apples, and in the processing of fruit wine at the enantiomeric level. RESULTS: Analysis method was established to determine imazalil and imazalil-M enantiomers in grape, apple, fruit wine and pomace. The method showed acceptable recoveries of 71.6-99.9% and precision with relative standard deviation of 0.3-11.7%. Processing factors (PFs) were 0.15-0.40 (for imazalil enantiomers) and <0.13-0.83 (for imazalil-M enantiomers) during the wine-making process. The PFs after individual steps including washing, peeling, fermentation, and clarification were all less than 1. No enantioselective dissipation of imazalil was found in grapes under field conditions with half-lives of 23.82-24.49 days. R-(-)-imazalil degraded slightly faster than S-(+)-imazalil in apples under field conditions with half-lives of 9.82-10.09 days. S-(+)-imazalil-M preferentially degraded in field grapes and apple. No significant enantioselectivity of imazalil and imazalil-M was observed during the wine-making process. The enantiomeric fraction (EF) values of imazalil were 0.484-0.511 and 0.509-0.522 in grape wine and cider, respectively. The EFs were 0.484-0.501(in grape wine) and 0.484-0.504 (in cider) for imazalil-M. CONCLUSION: The results showed that the wine-making process could reduce imazalil and imazalil-M residues in grapes and apples. The finding of non-enantioselectivity of imazalil during the processing of fruit wine was useful for accurate risk assessment for imazalil in raw and processing fruits. © 2021 Society of Chemical Industry.

High Azole Resistance in Aspergillus fumigatus Isolates from Strawberry Fields, China, 2018.

In 2018, we conducted a cross-sectional study to investigate azole resistance in environmental Aspergillus fumigatus isolates obtained from different agricultural fields in China. Using 63 soil cores, we cultured for azole-resistant A. fumigatus and characterized isolates by their cyp51A gene type, short tandem repeat genotype, and mating type. Of 206 A. fumigatus isolates, 21 (10.2%) were azole resistant. Nineteen of 21 had mutations in their cyp51A gene (5 TR34/L98H, 8 TR34/L98H/S297T/F495I, 6 TR46/Y121F/T289A). Eighteen were cultured from soil samples acquired from strawberry fields, suggesting this soil type is a potential hotspot for azole resistance selection. Twenty resistant isolates were mating type MAT1-1, suggesting asexual sporulation contributed to their evolution. Prochloraz, difenoconazole, and tebuconazole were the most frequently detected fungicides in soil samples with azole-resistant fungus. Our study results suggest that managing the fungicides used in agriculture will help contain the problem of antifungal drug resistance in clinics.

Enantioselective separation and dissipation of pydiflumetofen enantiomers in grape and soil by supercritical fluid chromatography-tandem mass spectrometry.

Pydiflumetofen is registered in many countries and is widely used in crop production in the racemate form. However, the environmental behavior of the enantiomers has not been studied. An effective and sensitive chiral analytical method was first established for analyzing the pydiflumetofen enantiomers by supercritical fluid chromatography with tandem triple quadrupole mass spectrometry. The enantiomers could be separated and detected using the Chiralcel OD-3 column in less than 3 min. The separation conditions were as follows: mobile phase, CO2 /methanol (80:20); flow rate, 1.0 mL/min; column temperature, 30°C, auto back-pressure regulator pressure, 2000 psi with modified quick, easy, cheap, effective, rugged, and safe sample treatment method. The average recoveries of analytes from both matrices at three spiking levels were in the range of 84.1-103.0%. The limit of quantitation for each enantiomer was 0.005 mg/kg with a baseline resolution of approximately 1.64. The method was applied to monitor the enantioselective dissipation of pydiflumetofen in grape and soil. In grapes, (-)-pydiflumetofen was degraded more rapidly than (+)-pydiflumetofen. In soil, (+)-pydiflumetofen was preferentially degraded. The data provided useful references for the risk assessment and rational use of pydiflumetofen in agriculture.

Enantioseparation and dissipation monitoring of oxathiapiprolin in grape using supercritical fluid chromatography tandem mass spectrometry.

Oxathiapiprolin is a chiral fungicide used in China for the prevention and treatment of grape downy mildew, but its potential risk could be inaccurately assessed without distinguishing its enantiomers. In this study, an effective and sensitive chiral analytical method was first established for quantification of oxathiapiprolin enantiomers using supercritical fluid chromatography tandem mass spectrometry. Baseline separation for oxathiapiprolin enantiomers was achieved for less than 3 min by using a Lux Cellulose-2 chiral column with the resolution of 1.51. The elution order of the eluting enantiomers was identified as (-)-oxathiapiprolin and (+)-oxathiapiprolin by an optical rotation detector. The grape samples were extracted by QuEChERS method, with the average recoveries of each enantiomer in grapes were in the range of 88.1-111.8% and the relative standard deviations were less than 18.9%. The enantioselective analysis of the dissipation of oxathiapiprolin in field grape samples showed that (-)-oxathiapiprolin was dissipated faster than (+)-oxathiapiprolin. The results indicate that this proposed method could provide data support for the risk assessment of oxathiapiprolin in agricultural produces in a more accurate way.

Development of S-Fluxametamide for Bioactivity Improvement and Risk Reduction: Systemic Evaluation of the Novel Insecticide Fluxametamide at the Enantiomeric Level.

Increasing numbers of novel pesticides have been applied in agriculture. However, traditional evaluation of pesticides does not distinguish between their enantiomers, which may lead to inaccurate results. In this study, systematic research on the chiral insecticide fluxametamide was conducted at the enantiomeric level. The methods for enantioseparation and semipreparative separation of fluxametamide enantiomers were developed. The optical rotation and absolute configuration of two enantiomers were determined, and their stability was verified in solvents and soils. Enantioselective bioactivities against four target pests (Plutella xylostella, Spodoptera exigua, Aphis gossypii, and Tetranychus cinnabarinus) were tested. Acute toxicities of fluxametamide enantiomers toward honeybees were also evaluated. S-(+)-Isomer exhibited 52.1-304.4 times and 2.5-3.7 times higher bioactivity than R-(-)-isomer and rac-fluxametamide, respectively. Meanwhile, rac-fluxametamide was more toxic than S/R-isomer, and S-(+)-isomer showed >30-fold higher acute toxicity than R-(-)-isomer. Molecular docking studies were performed with γ-aminobutyric acid receptor (GABAR) to monitor the mechanism of stereoselective bioactivity. The better Grid score of S-(+)-fluxametamide (-60.12 kcal/mol) than R-(-)-enantiomer (-56.59 kcal/mol) indicated higher bioactivity of S-(+)-isomer than of R-(-)-isomer. The dissipation of fluxametamide in cabbage, Chinese cabbage, and soil was nonenantioselective under field conditions. Development of S-(+)-fluxametamide could maintain the high-efficacy and low-risk properties, which should attract attention of producers, applicators, and managers of pesticides.

Human health safety studies of a new insecticide: Dissipation kinetics and dietary risk assessment of afidopyropen and one of its metabolites in cucumber and nectarine.

To preliminarily study the law of natural dissipation and the relation to human health of a new insecticide (afidopyropen), the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method and a UHPLC-MS/MS system were used to extract and detect the afidopyropen and its metabolite (M440I007) from cucumber and nectarine. The limits of quantitation (LOQs) of both target compounds in two matrixes were reduced to 0.0001 mg/kg. Dissipative dynamics experiments indicated that afidopyropen residue dissipation is more consistent with a two-compartment kinetic model than a first-order kinetic model whether in cucumber or nectarine. The half-lives were less than 1.1 and 2.0 days in the distribution phase and up to 9.9 and 27.7 days in the elimination phase in cucumber and nectarine, respectively. The correlation coefficients were 0.9620, 0.9391, and 0.9923 for cucumber and 0.9676 and 0.9985 for nectarine from different locations. M440I007 initially increased rapidly, reached a maximum at 2 days, and then decreased gradually over time. Finally, dietary risk assessment indicated that the mixed residues of afidopyropen and M440I007 at the recommended dosage would not cause health concerns in population.

Simultaneous determination of broflanilide and its metabolites in five typical Chinese soils by a modified quick, easy, cheap, effective, rugged, and safe method with ultra high performance liquid chromatography and tandem mass spectrometry.

An efficient and sensitive analytical method for simultaneous determination of trace amounts of a new insecticide broflanilide and its metabolites (S(PFH-OH)-8007 and DM-8007) residues in five typical Chinese soils (red soil, black soil, fluvo-aquic soil, cinnamon soil and paddy soil) was developed. The samples were prepared by a modified quick, easy, cheap, effective, rugged, and safe method. The determination of broflanilide and its metabolites was conducted by ultra high performance liquid chromatography with tandem mass spectrometry with an electrospray ionization source in the positive ion mode. This is the first report for the determination of broflanilide and its metabolites in different soils. Broflanilide and its metabolites were extracted from all soils with acetonitrile and purified by a mixture of primary secondary amine and graphitized carbon black. The average recoveries of the three compounds in five types of soil ranged from 85.3 to 111.8% and the relative standard deviations were less than 13.6%. The limit of quantification was 0.1 µg/kg for all three compounds. This method was successfully used to determine broflanilide and its metabolites in five types of soil. The method was validated to be simple and effective for the determination of trace residual broflanilide and its metabolites in five types of soil.

Enantioselective monitoring of chiral fungicide famoxadone enantiomers in tomato, apple, and grape by chiral liquid chromatography with tandem mass spectrometry.

Famoxadone is a widely used chiral fungicide on tomato, apple, and grape. But it is still being employed as a racemic mixture without distinguishing the difference between enantiomers, which often leads to its inaccurate risk assessment. In this study, a rapid, sensitive, and reliable chiral analytical method was developed for famoxadone enantiomers by ultra high performance liquid chromatography/tandem mass spectrometry, optimal separation condition was achieved with Lux Amylose-1 column using acetonitrile/water (70:30, v/v) as mobile phase at 0.3 mL/min in 6 min. The average recoveries for two enantiomers in all of the matrices at three spiking levels ranged from 89.8 to 109.4%, with relative standard deviation less than 9.5%. The limits of quantification for all enantiomers in tomato, apple, and grape were not more than 4 µg/kg. And the proposed method was successfully applied to investigate the enantioselective degradation of famoxadone enantiomers in tomato, apple, and grape. The data showed that S-(+)-famoxadone was preferentially degraded comparing to the R-(-)-famoxadone in tomato, apple, and grape. The potential reasons of the enantioselective behavior were also discussed. This study could help in better understanding the environmental fate of famoxadone and the rational use of chiral pesticide in agricultural production.

Determination and dissipation of afidopyropen and its metabolite in wheat and soil using QuEChERS-UHPLC-MS/MS.

The dissipations of afidopyropen and its metabolite in wheat plant and soil were determined using a quick, easy, cheap, effective, rugged, and safe method with ultra-high performance liquid chromatography and tandem mass spectrometry under a field ecosystem. The limits of quantification were estimated for both target compounds as 0.001 mg/kg. The recoveries of afidopyropen and its metabolite ranged from 94 to 114% (soil), 90 to 109% (wheat seed) and 81 to 91% (wheat straw) at levels of 0.001, 0.01, 0.1, and 2.0 mg/kg with relative standard deviations ≤7%. The results of the residual dynamics experiments showed that afidopyropen dissipated rapidly in wheat plant and soil. Its metabolite initially showed a tendency of rapid increase followed by a decrease in wheat plant but could not be detected in soil. The data showed that the first + first-order model was more suitable for describing the decline of afidopyropen in wheat and soil. The half-lives of afidopyropen in wheat plant and soil were 1.65 and 1.21 days, respectively.

Ultra high performance liquid chromatography with tandem mass spectrometry method for determining dinotefuran and its main metabolites in samples of plants, animal-derived foods, soil, and water.

An ultra high-performance liquid chromatography with tandem triple quadrupole mass spectrometry residue method was developed and validated for the quantification and identification of dinotefuran and its main metabolites 1-methyl-3-(tetrahydro-3-furylmethyl) urea and 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine in fruit (watermelon), vegetable (cucumber), cereal (rice), animal-derived foods (milk, egg, and pork), soil, and water. The samples were extracted with acetonitrile containing 15% v/v acetic acid and purified with dispersive solid-phase extraction with octadecylsilane, primary secondary amine, graphitized carbon black, or zirconia-coated silica prior to analysis. The method had an excellent linearity (R2  ≥ 0.9942, 1-500 µg/L) and satisfactory recoveries (73-102%) at five spiked levels (0.001, 0.01, 0.05, 0.5, and 2 mg/kg) with intra- or interday precision in the range of 0.8-9.5% and 3.0-12.8% for the three compounds in the eight matrices. The limits of quantification were 10 µg/kg for 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine and 1 µg/kg for 1-methyl-3-(tetrahydro-3-furylmethyl) urea and dinotefuran. The applicability of the developed method was demonstrated by determining the occurrence of dinotefuran, 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine, and 1-methyl-3-(tetrahydro-3-furylmethyl) urea in various samples from plants, animal-derived foods, and the environment. From 80 samples, 70 contained dinotefuran (0.8-11.7 µg/kg), among which six also contained 1-methyl-3-(tetrahydro-3-furylmethyl) urea (water and rice, 0.5-0.9 µg/kg).

Impact of fomesafen on the soil microbial communities in soybean fields in Northeastern China.

Fomesafen, a widely adopted residual herbicide, is used throughout the soybean region of northern China for the spring planting. However, the ecological risks of using fomesafen in soil remain unknown. The aim of this work was to evaluate the impact of fomesafen on the microbial community structure of soil using laboratory and field experiments. Under laboratory conditions, the application of fomesafen at concentrations of 3.75 and 37.5mg/kg decreased the basal respiration (RB) and microbial biomass carbon (MBC). In contrast, treatment with 375mg/kg of fomesafen resulted in a significant decrease in the RB, MBC, abundance of both Gram+ and Gram- bacteria, and fungal biomass. Analysis of variance showed that the treatment accounted for most of the variance (38.3%) observed in the soil microbial communities. Furthermore, the field experiment showed that long-term fomesafen application in continuously cropped soybean fields affected the soil bacterial community composition by increasing the relative average abundance of Proteobacteria and Actinobacteria species and decreasing the abundance of Verrucomicrobia species. In addition, Acidobacteria and Chloroflexi species showed a pattern of activation-inhibition. Taken together, our results suggest that the application of fomesafen can affect the community structure of soil bacteria in the spring planting soybean region of northern China.