Consequences of the matrix effect on recovery of dinotefuran and its metabolites in green tea during tandem mass spectrometry analysis

Chromatographic Comparison of Commercially Available Columns for Liquid Chromatography in Polar Pesticide Detection and Quantification Using a Score-Based Methodology

The detection and quantification of polar pesticides in liquid chromatography coupled with mass spectrometry present significant analytical challenges. This study compares the performance of three LC columns (Hypercarb™, Raptor Polar X™, and Anionic Polar Pesticide™) in separating and quantifying eleven polar pesticides in chicken eggs using a score-based methodology. Analytes include glyphosate, its metabolites, and other high-polarity pesticides like Ethephon, Glufosinate, and Fosetyl aluminum, included in the EU's official control plan. Polar pesticides, characterized by high polarity and hydrophilicity, lead to analytical issues such as poor retention and unconventional peak shapes with traditional reversed-phase methods. Their weak interaction with hydrophobic stationary phases complicates separation, necessitating specific stationary phases to enhance retention and selectivity. This study evaluates these columns' efficacy in complex matrices like chicken eggs and other food samples. Chromatographic separation was performed using a UPLC system coupled with a Q-TOF mass spectrometer; extraction and purification involved freeze-out, centrifugation, and filtration steps. The study highlights the critical role of column selection in achieving accurate and reliable separation and quantification of highly polar analytes in matrices of animal origin, offering in the meantime an easy-to-apply methodology of selection for the right determination of the best chromatographic column for different purposes.

Dissipation and residue of triadimefon in Rosa roxburghii

Rosa roxburghii (R. roxburghii) is a unique, edible, medicinal fruit rich in vitamin C found in Southwest China. Triadimefon (TDF) is a triazole fungicide that is widely used to control powdery mildew in R. roxburghii. To assess the safety of TDF in R. roxburghii, an LC-MS/MS method was developed for the simultaneous quantification of TDF and its major metabolite, triadimenol (TDN) in R. roxburghii. Both TDF and TDN showed high correlation coefficients (>0.999) for the solvent- and matrix-matched calibrations. The recovery rates of TDF and TDN in R. roxburghii ranged from 90.18% to 100.42%, with a relative standard deviation (RSD) of 1.25%-9.22%. The limit of quantification (LOQ) was 0.01 mg·kg-1. The half-life of TDF in R. roxburghii was between 2.74 and 3.07 days, with terminal residues ranging from < LOQ to 1.84 mg·kg-1. Recommended maximum residue limits (MRLs) and safe pre-harvest intervals (PHIs) for TDF in R. roxburghii were 0.5 mg·kg-1 and 21 days, respectively. This study provides essential data for TDF's safe and judicious use in R. roxburghii production.

Neonicotinoid insecticides in plant-derived Foodstuffs: A review of separation and determination methods based on liquid chromatography

Neonicotinoids (NEOs) are the most widely used insecticides globally. They can contaminate or migrate into foodstuffs and exert severe neonic toxicity on humans. Therefore, lots of feasible analytical methods were developed to assure food safety. Nevertheless, there is a lack of evaluation that the impacts of food attributes on the accurate determination of NEOs. This review aims to provide a comprehensive overview of sample preparation methods regarding 6 categories of plant-derived foodstuffs. Currently, QuEChERS as the common strategy can effectively extract NEOs from plant-derived foodstuffs. Various enrichment technologies were developed for trace levels of NEOs in processed foodstuffs, and multifarious novel sorbents provided more possibility for removing complex matrices to lower matrix effects. Additionally, detection methods based on liquid chromatography were summarized and discussed in this review. Finally, some limitations were summarized and new directions were proposed for better advancement.

Residual behavior of dinotefuran and its metabolites during Huangjiu fermentation and their effects on flavor

Yellow rice wine (Huangjiu) is a traditional Chinese alcoholic beverage. However, there is a risk of pesticide residues in Huangjiu due to pesticide indiscriminate use. In this study, the residues of dinotefuran and its metabolites during Huangjiu fermentation and their effects on flavor substances were studied. The initial concentrations of dinotefuran ranged from 856.3 to 1874.9 μg/L, and its half-life was no more than 3.65 d. At 24 d of Huangjiu fermentation, the terminal residues of dinotefuran, 1-methyl-3-(tetrahydro-3-furylmethyl)urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl)guanidine (DN) were 195.1-535.3 μg/L, 38.33-48.70 μg/L and 37.8-74.1 μg/L, respectively. Twenty potential degradation compounds were identified by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS), and their toxicity was evaluated. Finally, the effect of dinotefuran on physicochemical properties and total phenol content of Huangjiu were analyzed. The risk of rancidity was significantly increased and bitter amino acids were formed. These findings provide a guidance and the safe production of Huangjiu.

Covalent organic framework-sodium alginate-Ca2+-polyacrylic acid composite beads for convenient dispersive solid-phase extraction of neonicotinoid insecticides in fruit and vegetables

Neonicotinoids, the fastest-growing class of insecticides, have posed a multi-media residue problem with adverse effects on environment, biodiversity and human health. Herein, covalent organic framework-sodium alginate-Ca2+-polyacrylic acid composite beads (CACPs), facilely prepared at room temperature, were used in convenient dispersive solid-phase extraction (dSPE) and combined with high-performance liquid chromatography (HPLC) for the detection of five neonicotinoid insecticides (thiamethoxam, acetamiprid, dinotefuran, clothianidin, imidacloprid). CACPs can be completely separated within 1 min without centrifugation. After seven adsorption/desorption cycles, it maintained high extraction efficiencies (>90%). The developed method exhibited a wide linear range (0.01 ∼ 10 μg mL-1), low limits of detection (LODs, 0.0028 ∼ 0.0031 mg kg-1), and good repeatability (RSD ≤ 8.11%, n = 3). Moreover, it was applied to the determination of five neonicotinoids in fruit and vegetables (peach, pear, lettuce, cucumber, tomato), and recoveries ranged from 73.6% to 116.2%.

Persistence and recovery of dinotefuran in eastern hemlock (Tsuga canadensis) foliage and twigs by UPLC-MS/MS and ELISA

BACKGROUND

Dinotefuran, a systemic neonicotinoid insecticide, is approved for control of hemlock woolly adelgid (HWA) (Adelges tsugae Annand), an invasive sap-feeding insect that can kill eastern hemlocks (Tsuga canadensis). Dinotefuran is highly water soluble, facilitating more rapid translocation and HWA control than other neonicotinoids, but its persistence is not well-known. Samples of needles and twigs were collected in spring 2021 from 50 hemlocks treated with a dinotefuran basal trunk spray in 2018 or 2019 (131-145 weeks and 85-93 weeks before sampling, respectively). Processed samples were analyzed with ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) and enzyme-linked immunosorbent assays (ELISA).

RESULTS

Dinotefuran residues were 4.6-6.1 times higher in needles than in twigs collected from the same trees. Average (±SE) residues in foliage samples collected from trees treated in 2019 ranged from 0.663 ± 0.243 to 0.564 ± 0.119 mg kg-1 , compared with 0.213 ± 0.033 and 0.225 ± 0.132 mg kg-1 in foliage from trees treated in 2018. Foliage residues from UPLC-MS/MS were consistently lower but strongly related to those from ELISA. Matrix effects appeared to disrupt ELISA analysis of twigs. None of the 25 trees treated in 2019 had live HWA when samples were collected in 2021 while low densities of HWA were observed on 52% of trees treated in 2018.

CONCLUSIONS

Dinotefuran was recovered from hemlock foliage, and to a lesser extent twigs, >2 years post-treatment. This, along with its relatively rapid translocation, suggests dinotefuran is a viable option for protecting declining or heavily infested hemlocks from HWA. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

High-throughput analytical methodology of monoalkyl phthalate esters and the composite risk assessment with their parent phthalate esters in aquatic organisms and seawater

A sensitive, robust, and highly efficient analytical methodology involving solid phase extraction coupled to ultra-high performance liquid chromatography tandem mass spectrometry was successfully established to detect 13 monoalkyl phthalate esters (MPAEs) in aquatic organisms and seawater. After the organisms were preprocessed using enzymatic deconjugation with β-glucuronidase, extraction, purification, and qualitative and quantitative optimization procedures were performed. Under optimal conditions, the limits of detection varied from 0.07 to 0.88 μg/kg (wet weight) and 0.04-1.96 ng/L in organisms and seawater, respectively. Collectively, MPAEs achieved acceptable recovery values (91.0-102.7%) with relative standard deviations less than 10.4% and matrix effects ranging from 0.93 to 1.07 in the above matrix. Furthermore, MPAEs and phthalate esters were detected by the developed methodology and gas chromatography-triple quadrupole tandem mass spectrometer in practical samples, respectively. Mono-n-butyl phthalate and mono-iso-butyl phthalate were the most predominant congeners, accounting for 24.8-35.2% in aquatic organisms and seawater. Comprehensive health and ecological risks were higher after the MPAEs were incorporated than when phthalate esters were considered separately, and greater than their risk threshold. Therefore, the risks caused by substances and their metabolites in multiple media, with analogous structure-activity relationships, should be considered to ensure the safety of aquatic organisms and consumers.

Photolysis of dinotefuran in aqueous solution: Kinetics, influencing factors and photodegradation mechanism

The environmental behaviour of neonicotinoid insecticides (NNIs) is of momentous concern due to their frequent detection in aquatic environment and their biotoxicity for non-target organisms. Phototransformation is one of the most significant transformation processes, which is directly related to NNIs exposure and environmental risks. In this study, the photodegradation of dinotefuran (DIN, 1-Methyl-2-nitro-3-(tetrahydro-3-furanylmethyl)-guanidine), one of the most promising NNIs, was conducted under irritated light in the presence of Cl-, DOM along with the effect of pH and initial concentration. The findings demonstrated that in ultra-pure (UP) water, the photolysis rate constants (k) of DIN rose with increasing initial concentration. Whereas, in tap water, at varied pH levels, and in the presence of Cl-, the outcomes were reversed. At the same time, lower concentration of DOM promoted DIN photolysis processes due to the production of reactive oxygen species, while higher concentrations of DOM inhibited the photolysis by the predominance of light shielding effects. The singlet oxygen (1O2) was produced in the photolysis processes of DIN with Cl- and DOM, which was confirmed by electron spin resonance (EPR) analysis. Four main photolysis products and three intermediates were identified by UPLC-Q-Exactive Orbitrap MS analysis. The possible photodegradation pathways of DIN were proposed including the oxidation by 1O2, reduction and hydrolysis after the removal of nitro group from parent compounds. This study expanding our understanding of transformation behavior and fate of NNIs in the aquatic environment, which is essential for estimating their environmental risks.

Ecotoxicological impact of dinotefuran insecticide and its metabolites on non-targets in agroecosystem: Harnessing nanotechnology- and bio-based management strategies to reduce its impact on non-target ecosystems

The class of insecticides known as neonicotinoid insecticides has gained extensive application worldwide. Two characteristics of neonicotinoid pesticides are excellent insecticidal activity and a wide insecticidal spectrum for problematic insects. Neonicotinoid pesticides can also successfully manage pest insects that have developed resistance to other insecticide classes. Due to its powerful insecticidal properties and rapid plant absorption and translocation, dinotefuran, the most recent generation of neonicotinoid insecticides, has been widely used against biting and sucking insects. Dinotefuran has a wide range of potential applications and is often used globally. However, there is growing evidence that they negatively impact the biodiversity of organisms in agricultural settings as well as non-target organisms. The objective of this review is to present an updated summary of current understanding regarding the non-target effects of dinotefuran; we also enumerated nano- and bio-based mitigation and management strategies to reduce the impact of dinotefuran on non-target organisms and to pinpoint knowledge gaps. Finally, future study directions are suggested based on the limitations of the existing studies, with the goal of providing a scientific basis for risk assessment and the prudent use of these insecticides.

Simultaneous analysis of advanced glycation end products using dansyl derivatization

Herein, new pre-column derivatization based on dansylation is present to resolve analytical difficulties, such as chromatographic separation difficulty, in identifying and quantifying advanced glycation end products (AGEs) owing to their high hydrophilicity, wide variety, and structural similarity. The proposed analytical method facilitated the separation of 14 AGEs, including structural isomers. Limits of detection of 1.0-43.3 ng/mL and linear ranges of the double- or triple-digit were achieved. Intra- and inter-day precisions of 1.1-3.0% and 1.3-3.1%, respectively, were achieved for standard solutions, while those for food specimens were 1.4-11.2% and 1.7-15.7%, respectively. The matrix effect was insignificant with regard to the percent recoveries and differences between slopes for both the standard solutions and food specimens. Furthermore, the quantitation results of AGEs in foods (coffee, beer, and sausage) and glycated proteins revealed the potential applicability of the developed method in various fields of food chemistry and biochemistry.

Dissipation, residue and dietary risk assessment of difenoconazole in Rosa roxburghii

Rosa roxburghii is a medicinal and edible plant, which is favored by consumers due to its rich vitamin C content. Residues and potential health risks of difenoconazole in the R. roxburghii ecosystem has aroused a concern considering its extensive use for controlling the powdery mildew of R. roxburghii. In this study, the residue of difenoconazole in R. roxburghii and soil was extracted by acetonitrile, purified by primary secondary amine and detected by liquid chromatography-tandem triple quadrupole mass spectrometry. The average recoveries in R. roxburghii and soil matrix varied from 82.59% to 99.63%, with relative standard deviations (RSD) of 1.14%-8.23%. The limit of quantification (LOQ) and detection (LOD) of difenoconazole in R. roxburghii and soil samples were 0.01 mg/kg. The dissipation of difenoconazole followed well the first-order kinetic, with a half-life of 3.99-5.57 d in R. roxburghii and 4.94-6.23 d in soil, respectively. And the terminal residues were <0.01-2.181 mg/kg and 0.014-2.406 mg/kg, respectively. The chronic and acute risk quotient values of difenoconazole were respectively 0.42% and 4.1%, which suggests that the risk was acceptable and safe to consumers. This study provides a reference for the safe and reasonable use of difenoconazole in R. roxburghii production.

Migration behavior and dietary exposure risk assessment of pesticides residues in honeysuckle (Lonicera japonica Thunb.) based on modified QuEChERS method coupled with tandem mass spectrometry

The honeysuckle was widely appreciated as tea beverage owing to the biological activities and the unique aroma and flavor. It is in urgent requirement to explore the migration behavior and dietary exposure as the pesticide residues would bring about potential risks through honeysuckle intake. The optimized QuEChERS procedure coupled with the HPLC-MS/MS and GC-MS/MS methods were employed to determine 93 pesticide residues of seven classifications including carbamates, pyrethroid, triazoles, neonicotinoids, organophosphorus, organochlorine, and others for 93 honeysuckle samples from four primary production bases. As a result, 86.02% of the samples were contaminated by at least one pesticide. Unexpectedly, the banned pesticide of carbofuran was also identified. The migration behavior of metolcarb was the highest, whereas thiabendazole contributed less risk to the infusion with relative lower transfer rate. Both the chronic and acute exposure yielded low risk for human health with five high risk pesticides of dichlorvos, cyhalothrin, carbofuran, ethomyl, and pyridaben. Besides, this study provides foundation of dietary exposure risk assessment for honeysuckle and other likewise products.

Development of a polyurethane-coated thin film solid phase microextraction device for multi-residue monitoring of pesticides in fruit and tea beverages

A novel solid-phase microextraction device coated with an efficient and cheap thin film of polyurethane was developed for trace determination of 13 widely used pesticides in fruit and tea beverages. A round-shaped polyurethane film covering the bottom of a glass vial was fabricated as the sorbent to exhibit a superior capacity for preconcentrating target compounds and reducing matrix interferences. After optimization of the key parameters including the film type, extraction time, solution pH, ionic strength, desorption solvent, and conditions, this device allowed an efficient adsorption-desorption cycle for the pesticides accomplished in one vial. Coupled with gas chromatography-electron capture detection, the polyurethane-coated thin film microextraction method was successfully established and applied for the analysis of real fruit and tea drinks, showing low limits of detection (0.001-0.015 μg/L), wide linear ranges (1.0-500.0 μg/L, r²  > 0.9931), good relative recoveries (77.2%-106.3%) and negligible matrix effects (86.1%-107.5%) for the target pesticides. The proposed approach revealed strong potential of extending its application by flexibly modifying the type or size of the coating film. This study provides insights into the enrichment of contaminants from complex samples using inexpensive and reusable microextraction devices that can limit the environmental and health impact of the sample preparation protocol.

A Nationwide Study of Residual Fate of Fluxapyroxad and Its Metabolites in Peanut Crops Across China: Assessment of Human Exposure Potential

Elaborating on the residual fate of fluxapyroxad and its metabolites based on their nationwide application was vital to protect the human population from their hazardous effects. In this study, a rapid and sensitive analytical method was developed to trace fluxapyroxad and two of its metabolites in peanut matrices using an ultrahigh chromatography method coupled with mass spectrometry (UHPLC−MS/MS) within 3.5 min. The occurrence, pharmacokinetic degradation and terminal magnitudes of fluxapyroxad were reflected in the original deposition of 8.41−38.15 mg/kg, half−lives of 2.5−8.6 d and final concentrations of 0.004−37.38 mg/kg in peanut straw. The total concentrations of fluxapyroxad in peanut straw (0.04−39.28 mg/kg) were significantly higher than those in peanut kernels (<0.001−0.005 mg/kg) and an obvious concentration effect was observed in fresh (0.01−11.56 mg/kg) compared dried peanut straw (0.04−38.97 mg/kg). Fluxapyroxad was demethylated to 3−(difluoromethyl)−N−(3′,4′,5′−trifluoro[1,1′−biphenyl]−2−yl)−1H−pyrazole−4−carboxamide (M700F008, 0.02−5.69 mg/kg) and further N−glycosylated to 3−(difluoromethyl)−1−(ß−D−glucopyranosyl)−N−(3′,4′,5′−triflurobipheny−2−yl)−1H−pyrzaole−4−carboxamide (M700F048, 0.04−39.28 mg/kg).The risk quotients of the total fluxapyroxad for the urban groups were significantly higher than those for the rural groups, and were both negatively correlated with the age of the groups, although both acute (ARfD%, 0.006−0.012%) and chronic (ADI%, 0.415−1.289%) risks are acceptable for the human population. The high-potential health risks of fluxapyroxad should be continuously emphasized for susceptible toddlers (1−3 years), especially those residing in urban areas.

Risk Assessment of Triflumezopyrim and Imidacloprid in Rice through an Evaluation of Residual Data

Triflumezopyrim, a novel mesoionic insecticide used to control planthoppers, is a potential substitute for imidacloprid. In this study, triflumezopyrim and imidacloprid residues in rice were determined using a quick, easy, cheap, effective, rugged, and safe procedure combined with ultra-high-performance liquid chromatography–tandem mass spectrometry. The limit of quantification of both triflumezopyrim and imidacloprid was 0.01 mg kg⁻¹, and the average recovery values were 94–104% and 91–106%, with relative standard deviations (RSDs) of 1.1–1.4% and 2.1–3.4% (n = 5), respectively. The consumer protection level was assessed by calculating the theoretical maximum daily intake using the reported maximum residue limits of triflumezopyrim and imidacloprid. The established method was successfully applied to 200 commercial rice samples collected from four provinces in China, and their potential public health risks were assessed using triflumezopyrim and imidacloprid residues. The risk associated with triflumezopyrim and imidacloprid dietary intake was assessed by calculating the national estimated short-term intake and the acute reference dose percentage (%ARfD). The results show that the theoretical maximum daily intake (NEDI) values of triflumezopyrim and imidacloprid in different age and gender groups were 0.219–0.543 and 0.377–0.935 μg kg⁻¹ d⁻¹ bw, and the risk quotient (RQ) values were 0.188–0.467% and 0.365–0.906%, respectively. The acute reference dose (%ARfD) of triflumezopyrim and imidaclopridin ranged from 0.615 to 0.998% and from 0.481 to 0.780%, respectively.

Dissipation and Residues of Pyraclostrobin in Rosa roxburghii and Soil under Filed Conditions

Rosa roxburghii has been widely planted in China. Powdery mildew is the most serious disease of R. roxburghii cultivation. Pyraclostrobin was widely used as a novel fungicide to control powdery mildew of R. roxburghii. To assess the safety of pyraclostrobin for use on R. roxburghii fruits, its residue rapid analysis as well as an investigation on its dissipation behaviors and terminal residues in R. roxburghii and soil under field conditions were carried out. The QuEChERS method was simplified using LC−MS/MS detection and combined with liquid−liquid extraction purification to allow determination of pyraclostrobin levels in R. roxburghii fruits and the soil. The fortified recoveries at 0.1~5.0 mg/kg were 93.48~102.48%, with the relative standard deviation of 0.64~3.21%. The limit of detection of the analytical method was 0.16 and 0.15 µg/kg for R. roxburghii fruit and soil, respectively. The effects of different spray equipment and formulations on the persistence of pyraclostrobin in R.roxburghii were as follows: gaston gasoline piggyback agricultural sprayer (5.38 d) > manual agricultural backpack sprayer (3.37 d) > knapsack multi-function electric sprayer (2.91 d), suspension concentrate (SC) (6.78 d) > wettable powder (WP) (5.64 d) > water dispersible granule (WG) (4.69 d). The degradation of pyraclostrobin followed the first-order kinetics and its half-lives in R.roxburghii and soil were 6.20~7.79 days and 3.86~5.95 days, respectively. The terminal residues of pyraclostrobin in R. roxburghii and soil were 0.169~1.236 mg/kg and 0.105~3.153 mg/kg, respectively. This study provides data for the establishment of the maximum residue limit (MRL) as well as the safe and rational use of pyraclostrobin in R. roxburghii production.

Development, Validation, and Application of the UPLC-DAD Methodology for the Evaluation of the Qualitative and Quantitative Composition of Phenolic Compounds in the Fruit of American Cranberry (Vaccinium macrocarpon Aiton)

Phenolic compounds in the fruit of American cranberry (Vaccinium macrocarpon Aiton) determine the antioxidant, anti-inflammatory, anticancer, and other biological effects. The berries are used in the production of medicinal preparations and food supplements, which highlights the importance of qualitative and quantitative analysis of phenolic compounds in cranberry fruit raw material. The aim of our study was to develop and validate an efficient, cost-effective, reproducible, and fast UPLC-DAD methodology for the evaluation of the qualitative and quantitative composition of phenolic compounds in raw material and preparations of American cranberry fruit. During the development of the methodology, chlorogenic acid and the following flavonols were identified in cranberry fruit samples: myricetin-3-galactoside, quercetin-3-galactoside, quercetin-3-glucoside, quercetin-3-α-L-arabinopyranoside, quercetin-3-α-L-arabinofuranoside, quercetin-3-rhamnoside, myricetin, and quercetin. The developed and optimized UPLC-DAD methodology was validated according to the guidelines of the International Council for Harmonization (ICH), evaluating the following parameters: range, specificity, linearity (R² > 0.999), precision (%RSD < 2%), LOD (0.38–1.01 µg/mL), LOQ (0.54–3.06 µg/mL), and recovery (80–110%). The developed methodology was applied to evaluate the qualitative and quantitative composition of phenolic compounds in fruit samples of cranberry cultivars ‘Baifay’, ‘Bergman’, ‘Prolific’, and ‘Searles’, as well as ‘Bain-MC’ and ‘BL-12′ clones. In the tested samples, the majority (about 70%) of the identified flavonols were quercetin derivatives. The greatest amount of quercetin-3-galactoside (1035.35 ± 4.26 µg/g DW) was found in fruit samples of the ‘Searles’ cultivar, and the greatest amount of myricetin-3-galactoside (940.06 ± 24.91 µg/g DW) was detected in fruit samples of the ‘Woolman’ cultivar.

Quantification of carbohydrates in human serum using gas chromatography–mass spectrometry with the stable isotope-labeled internal standard method

Comparison of two derivatization approaches (silylation and acylation) for carbohydrate separation based on optimizing reaction conditions by artificial neural networks.

Combination of polyurethane and polymethyl methacrylate thin films as a microextraction sorbent for rapid adsorption and sensitive determination of neonicotinoid insecticides in fruit juice and tea by ultra high performance liquid chromatography with tandem mass spectrometry

An economical and effective thin film microextraction (TFME) for simultaneous analysis of ten neonicotinoid insecticides and metabolites in fruit juice and tea, was developed based on the combination of polyurethane (PU) and polymethyl methacrylate (PMMA) films as the sorbent followed by ultra high performance liquid chromatography with tandem mass spectrometry. The PU/PMMA composite was evidenced to possess rapid adsorption and strong accumulation towards neonicotinoids compared with the films used alone. A series of parameters were optimized, and the agitation mode, film size, ionic strength, desorption solvent and sample pH were found to dominate the microextraction process rather than the extraction temperature, agitation time and sample volume. The thin films are cost effective and efficient for single use analysis, but still can be reused at least 8 times with no significant loss in performance. The ten neonicotinoids were measured with good recoveries (81.1-107.9%), high enrichment factors (up to 135), low limits of detection (0.001-0.1 µg L^-1), and wide linearity range (1-500 µg L^-1, r²>0.9981) in fruit juice (apple, lemon, and pomegranate) and tea (green tea and black tea) samples. The proposed method was successfully applied to commercial fruit and tea drinks, and no samples were tested positive on target neonicotinoids. The PU/PMMA based TFME has shown great potential as an alternative to exhaustive extraction techniques for routine screening of trace neonicotinoids in fruit juice and tea by simplifying the analytical procedure, shortening the operation time, and lowering the material expense.

A Pencil-Lead Immunosensor for the Rapid Electrochemical Measurement of Anti-Diphtheria Toxin Antibodies

Diphtheria is a vaccine-preventable disease, yet immunization can wane over time to non-protective levels. We have developed a low-cost, miniaturized electroanalytical biosensor to quantify anti-diphtheria toxin (DTx) immunoglobulin G (anti-DTx IgG) antibody to minimize the risk for localized outbreaks. Two epitopes specific to DTx and recognized by antibodies generated post-vaccination were selected to create a bi-epitope peptide, biEP, by synthesizing the epitopes in tandem. The biEP peptide was conjugated to the surface of a pencil-lead electrode (PLE) integrated into a portable electrode holder. Captured anti-DTx IgG was measured by square wave voltammetry from the generation of hydroquinone (HQ) from the resulting immunocomplex. The performance of the biEP reagent presented high selectivity and specificity for DTx. Under the optimized working conditions, a logarithmic calibration curve showed good linearity over the concentration range of 10-5-10-1 IU mL-1 and achieved a limit of detection of 5 × 10-6 IU mL-1. The final device proved suitable for interrogating the immunity level against DTx in actual serum samples. Results showed good agreement with those obtained from a commercial enzyme-linked immunosorbent assay. In addition, the flexibility for conjugating other capture molecules to PLEs suggests that this technology could be easily adapted to the diagnoses of other pathogens.

Residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and its metabolites during tea growing and tea brewing

BACKGROUND

Tolfenpyrad and dinotefuran are two representative pesticides used for pest control in tea gardens. Their application may bring about a potential risk to the health of consumers. Therefore, it is essential to investigate the residue behavior, transfer and risk assessment of tolfenpyrad, dinotefuran and metabolites from tea garden to teacup.

RESULTS

An effective analytical method was established and validated to simultaneously determine tolfenpyrad, dinotefuran and its metabolites (DN and UF) in tea. The average recoveries of tolfenpyrad, dinotefuran, DN and UF were in the range 72.1-106.3%, with relative standard deviations lower than 11.8%. On the basis of the proposed method, the dissipation of tolfenpyrad and dinotefuran in fresh tea leaves followed first-order kinetics models with half-lives of 4.30-7.33 days and 4.65-5.50 days, respectively. With application amounts of 112.5-168.75 g a.i. ha^-1 once or twice, the terminal residues of tolfenpyrad and total dinotefuran in green tea were lower than 19.6 and 7.13 mg kg^-1 , respectively, and below their corresponding maximum residue limits . The leaching rates of tolfenpyrad and total dinotefuran during the tea brewing were in the ranges 1.4-2.3% and 93.7-98.1%, respectively.

CONCLUSION

Tolfenpyrad and dinotefuran in tea were easily degraded. The RQ_c and RQ_a values for tolfenpyrad were 37.6% and 5.4%, which were much higher than for dinotefuran at 24.7% and 0.84%, respectively. The data indicated that there was no significant health risk in tea for consumers at the recommended dosages. The results provide scientific data regarding the reasonable use of tolfenpyrad and dinotefuran aiming to ensure safe tea consuption. © 2021 Society of Chemical Industry.

Residual behavior and dietary intake risk assessment of flonicamid, dinotefuran and its metabolites on peach trees

BACKGROUND

Flonicamid and dinotefuran are widely applied to control pests and diseases in various economic crops arousing much public concerns about the potential risk to human health. In this study, the multi-determination and residual behavior of flonicamid-dinotefuran mixture on peach trees were investigated. The chronic risk of long-term dietary intake for Chinese consumers was evaluated.

RESULTS

An optimized QuEChERS method combined with ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis for simultaneous determination of flonicamid, dinotefuran and its metabolites was established to analyze the residual dissipation and terminal residues in peach matrices. The results demonstrated that (i) a satisfactory linearity relationship with the detector response and the correlation coefficient R² > 0.999, the average recoveries of these four analytes ranged from 94 to 108%, the relative standard deviation was between 1.0% and 8.8%, and the limit of the quantitation was 0.02 mg kg^-1 ; (ii) the dissipation behaviors of flonicamid and dinotefuran followed with the first-order dynamic kinetics model, and the half-lives were 6.9-12.4 days and 8.1-15.1 days, respectively; (iii) the recommended preharvest interval (PHI) was 21 days, the risk quotient (RQ) values of flonicamid and dinotefuran were 16.6 and 20.7%, respectively, which were significantly less than 100%.

CONCLUSION

The established analytical method met the detection requirement in terms of sensitivity, accuracy, and precision. Additionally, the results indicated that the potential dietary intake risk of the flonicamid-dinotefuran mixture on peach trees was negligible. This work can be utilized in the safe and responsible use of flonicamid-dinotefuran mixture and provide guidance for establishing its maximum residue limit (MRL) in China. © 2021 Society of Chemical Industry.

Residue changes and processing factors of eighteen field-applied pesticides during the production of Chinese Baijiu from rice

The fate of eighteen pesticides in field-collected rice samples during Chinese Baijiu production was systematically studied. The results indicated that steeping decreased flonicamid residue by 73.2% due to its high water-solubility and low octanol/water partition coefficient. The steaming step reduced pesticide residues by 32.0%-75.3% through evaporation or thermal degradation. After steaming, the pesticide residues were further reduced by 39.8-74.2% in fermentation which might be caused by biological degradation. In addition, distillation was shown to be most effective, responsible for greater than 90% losses of the remaining pesticide residues. The processing factors (PFs) were generally lower than 1 for different processes and the whole procedure. These results revealed that the procedure of Chinese Baijiu production could dramatically decrease residues of all the eighteen pesticides. Overall, this study provide important references for monitoring pesticide residue levels during the production of Chinese Baijiu from rice, and ensuring proper risk assessment from pesticide contamination.

A novel ISM-SAM strategy, based on gas chromatography/mass spectrometry analysis, to compensate for matrix effects in the determination of pyruvic acid

RATIONALE

The matrix effect is tricky in gas chromatography/mass spectrometry (GC/MS) analyses. Although several methods have been proposed to solve this problem, the results were unsatisfactory. Even fewer studies have assessed the performance of corrective methods. Hence, our study focused on assessing several common corrective methods, and then proposed a new strategy to correct for the matrix effect in GC/MS analyses.

METHODS

In GC/MS analyses, the internal standard method (ISM) was employed to overcome the matrix effect during the detection of pyruvic acid (PA) in serum samples from a healthy adult female. The accuracy of the ISM was evaluated by comparing it with the standard addition method (SAM). To employ the ISM-SAM strategy, correction factors (CFs) were established by combining the ISM and the SAM based on different groups. The CFs were used to normalize data onto the results of subsequent analyses.

RESULTS

When using the ISM to detect levels of PA, a serious bias is observed, thereby affecting the conclusions reached. In contrast, more reliable data can be obtained after normalizing results by undertaking the ISM-SAM strategy. The feasibility of this strategy was verified by comparing it with the results of the SAM alone. The ISM-SAM strategy was successfully applied to quantify the PA levels in healthy people and nephrotic syndrome patients.

CONCLUSIONS

Our results indicated that a false outcome was presented when only the ISM was used to adjust the data, and important information would be missed if the correction strategy was not carried out. Therefore, ISM-SAM, as an available correction method, should be adapted to improve the reliability of research results.

Enantioselective fate of dinotefuran from tomato cultivation to home canning for refining dietary exposure

Understanding the enantioselective fate of chiral neonicotinoid dinotefuran is of vital importance for accurate dietary exposure assessment and food safety regulation. The study investigated the enantioselectivity in respect to dissipation, metabolism, and removal, of dinotefuran from tomato cultivation to tomato paste processing. The chiral analytical method of dinotefuran, UF and DN was developed in tomato using ultrahigh performance supercritical fluid chromatography/tandem mass spectrometry. Under greenhouse cultivation R-dinotefuran preferentially degraded (T_1/2, 9.1-12.6 days), resulting in relative enrichment of S-dinotefuran (T_1/2, 10.3-13.3 days) by foliage and root uptake pathways. (-)-UF generated at a faster rate and was more persistent than its antipode in tomato by foliage treatment. Furthermore, changes in the enantiomeric removal and enantioselectivity orientation of dinotefuran and metabolites were evaluated during home canning of tomato paste, including washing, peeling, homogenization, simmering, and sterilization. Peeling played the key role in reducing S-dinotefuran by 67.3% and R-dinotefuran by 69.9% with processing factor of 0.313 and 0.287, respectively. Simmering was the most effective way to remove UF enantiomers (Pf, 0.336-0.421) by elevated temperature. This study sheds light on the chiral profiles of the fate of dinotefuran from cultivation to processing, providing scientific importance to protect human health from hazardous effects.

Neonicotinoid insecticide and their metabolite residues in fruit juices: Implications for dietary intake in China

Neonicotinoid insecticides (NEOs) have become the most widely used insecticides worldwide, and they are ubiquitous in food (i.e., fruit juices). In the present study, occurrence of seven NEOs and four metabolites (m-NEOs) in 400 fruit juice samples were investigated. NEOs and m-NEOs were frequently detected (65%-86%) in fruit juice samples. The median residues of NEOs and m-NEOs were ranged from 0.06 ng/mL to 0.94 ng/mL. Seasonal variations in NEOs and m-NEOs in fruit juices were found, indicating that the target analyte residues during the dry season were remarkably higher than those of residues during wet season. The relative potency factor (RPF) method was used to integrate individual NEOs into a single metric [imidacloprid (IMI_RPF)] representing the intakes of IMI equivalent to total NEOs for each fruit juice sample. The estimated daily intake (EDI) of total NEOs for the general Chinese population was obtained. The median IMI_RPF for total fruit juices was 13.4 ng/g, and the median EDI of NEOs was 18.2 ng/kg bw/day for the general population. Although the EDIs in this study were considerably lower than the acceptable daily intake (60 μg/kg bw/day, ADI), the dietary exposure risks for total NEOs should not be ignored because of the increasing usage of NEOs and their ubiquitous presence in fruit juices in China. To the best of our knowledge, this report was the first time to document residues of NEO and m-NEO in fruit juice samples collected from China.

Residue and toxicity of cyantraniliprole and its main metabolite J9Z38 in soil-earthworm microcosms

As part of a new generation of diamide insecticides, cyantraniliprole has broad application prospects. In the present study, a QuEChERS-UPLC-MS/MS method was established to determine the residues of cyantraniliprole and its main metabolite J9Z38 in soil and earthworms. Moreover, the accumulation and toxicity of cyantraniliprole and J9Z38 in earthworms were evaluated. The present results show that the detection method of cyantraniliprole and J9Z38 has high sensitivity and accuracy, which could be used for the accurate quantification of cyantraniliprole and J9Z38 residues in soil and earthworms. Additionally, cyantraniliprole degraded faster than its main metabolite J9Z38 in the artificial soil. Moreover, the bioenrichment efficiency of cyantraniliprole was higher than J9Z38. The toxicity test result showed that cyantraniliprole and J9Z38 could induce oxidative stress effect in earthworms from 5.0 mg/kg, finally resulting in cellular damage. Moreover, the oxidative damage degree induced by cyantraniliprole was higher than J9Z38. Combining the results of residue test and toxicity test, although cyantraniliprole degraded faster than its main metabolite J9Z38 in the artificial soil, its risk to earthworms was higher than J9Z38.

Residues and Dietary Risk Assessments of 2,4-D Isooctyl Ester, Metribuzin, Acetochlor, and 2-Ethyl-6-methylaniline in Corn or Soybean Fields

Since 2,4-dichlorophenoxy acetic acid (2,4-D) was discovered in the 1940s, 2,4-D and its derivatives remain among most commonly used herbicides in the world. There have been recent increases in using 2,4-D products in a combination with other herbicides such as metribuzin and acetochlor to control noxious weeds. However, accurate analysis of 2,4-D isooctyl ester remains to be improved due to long analysis time and rapid conversion of the ester to acid (i.e., under-reporting residues). In this work, a simple hydrolysis procedure was introduced to provide a quantitative hydrolytic rate of the ester (>95%) and did not affect the other pH-sensitive compounds. Analysis parameters and sample pretreatments were optimized for improved selectivity and accuracy. The hydrolysis-QuEChERS (quick, easy, cheap, effective, rugged, and safe) technique for multidetermination of 2,4-D isooctyl ester, metribuzin, acetochlor, and 2-ethyl-6-methylaniline in corn and soybeans via high performance liquid chromatography-tandem mass spectrometry was established. The method had average recoveries of 74-109% with relative standard deviations ≤13.5% and limits of quantifications (LOQs) of 0.05 mg/kg. The terminal residues of these compounds found in real edible matrixes were less than the corresponding LOQs at harvest time. The risk quotients were far below 100%, indicating a low health risk to consumers.

Self-acidity induced effervescence and manual shaking-assisted microextraction of neonicotinoid insecticides in orange juice

A novel dispersive liquid-liquid microextraction that combines self-induced acid-base effervescent reaction and manual shaking, coupled with ultra high performance liquid chromatography with tandem mass spectrometry was developed for simultaneous determination of ten neonicotinoid insecticides and metabolites in orange juice. An innovative aspect of this method was the utilization of the acidity of the juice for a self-reaction between acidic components contained in the juice sample and added sodium carbonate which generated carbon dioxide bubbles in situ, accelerating the analytes transfer to the extractant of 1-undecanol. The total acid content of juice sample was measured to produce the maximum amount of bubbles with minimum usage of carbonate. Manual shaking was subsequently adopted and was proven to enhance the extraction efficiency. The factors affecting the performance, including the type and the amount of the carbon dioxide source and extractant, and ionic strength were optimized. Compared with conventional methods, this approach exhibited low limits of detection (0.001-0.1 µg/L), good recoveries (86.2-103.6%), high enrichment factors (25-50), and negligible matrix effects (-12.3-13.7%). The proposed method was demonstrated to provide a rapid, practical, and environmentally friendly procedure due to no acid reagent, toxic solvent, or external energy requirement, giving rise to potential application on other high acid-content matrices.

Development of a High-Quality ELISA Method for Dinotefuran Based on a Novel and Newly-Designed Antigen

The structure of hapten determines the performance of the antibody and the corresponding detection method. A new type of antigen was designed and synthesized to expose the spatial and characteristic structure of dinotefuran molecule, and a type of high-quality antibody was obtained. The IC50 value of the monoclonal antibody was 5.30 ng/mL and its cross-reactivity (CRs) was less than 2% when reacting with other structurally related analytes. The effects of spatial configurations of hapten on the antibody were visually analyzed while using the appropriate software according to the quality of the antibodies, which showed that the specificity of the antibody is closely related with the exposed structure of hapten. An ELISA assay with an IC50 of 5.66 ng/mL and a linear range of 1.95 to 16.29 ng/mL was developed. The results that were obtained from the ELISA and HPLC methods were equivalent. The results showed that spatial simulation is a crucial method that is used in the designing of hapten to obtain a sensitive and specific antibody. The application of this method will highlight the potential aim and improve the detection efficiency of ELISA.

Determinations of dinotefuran and metabolite levels before and after household coffee processing in coffee beans using solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry

BACKGROUND

Coffee is one of the most popular beverages in the world. However, as daily consumables, coffee beans may contain pesticide residues that are capable of causing adverse health effects. Thus, we investigated residue dynamics in coffee beans using supervised field trials under Good Agricultural Practice conditions and determined the effects of household coffee processing on the coffee-bean pesticide residues dinotefuran and its metabolites 1-methyl-3-(tetrahydro-3-furylmethyl) urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl) guanidine (DN).

RESULTS

The recovery rate of dinotefuran and its metabolites UF and DN was in the range 73.5%-106.3%, with a relative SD < 10%. The limits of detection and limits of quantification for dinotefuran, UF and DN were all 0.003 and 0.01 mg kg^-1 , respectively. Dissipation experiments were conducted over 2015 and 2016 and showed a mean half-life of 40.8 days. Coffee processing procedures were performed as described for traditional household coffee processing in Ethiopia. Dinotefuran contents were reduced by 44.4%-86.7% with washing of coffee beans and the roasting process reduced these contents by 62.2%-100%. DN residues were not detected in roasted coffee beans before day 21 or in brewed coffee before day 35 and UF residues were not detected in brewed coffee before day 35. Kruskal-Wallis analyses indicated large variations in the stability of pesticide residues between processing methods (P ≤ 0.05). Reductions of pesticide concentrations with washing were also significantly lower than those following roasting (P = 0.0001) and brewing processes (P = 0.002). Moreover, processing factors were less than one for all processing stages, indicating reductions of pesticides contents for all processing stages.

CONCLUSION

The cumulative effects of the three processing methods are of paramount importance with respect to an evaluation of the risks associated with the ingestion of pesticide residues, particularly those in coffee beans. © 2018 Society of Chemical Industry.

The metabolism distribution and effect of dinotefuran in Chinese lizards (Eremias argus)

The Chinese lizards (Eremias argus) were used to evaluate the metabolism, distribution and effect of dinotefuran following oral exposed. The HPLC equipped with Q Exactive focus was used for metabolite identification and concentration analysis. After single oral administration, the time-concentration curves of dinotefuran and its metabolites were tissue-dependent. The liver and kidney were the major metabolic organs. Percutaneous and urinary excretions were the main ways for lizards to eliminate dinotefuran, and the urine output was the limiting factor. Nitro-reduction was an important process of the metabolism of dinotefuran that was dominated by aldehyde oxidase, and P450 enzymes were involved. The CYP3A4 and CYP2C19 played a crucial role in the other metabolic pathways of dinotefuran. The mRNA expressions of GST family were severely inhibited in liver, which showed dinotefuran might pose a risk of damaging the oxidative stress system in liver. Prolonged residuals of dinotefuran and its demethylation metabolite might enhance the risk of dinotefuran to brain. The results enrich and supplement the knowledge of the environmental fate of dinotefuran in reptiles.

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).

Simultaneous determination of pyridaben, dinotefuran, DN and UF in eggplant ecosystem under open-field conditions: Dissipation behaviour and residue distribution

A sensitive method for simultaneous determination of pyridaben, dinotefuran, DN and UF in eggplant ecosystem was established and validated through rapid resolution liquid chromatography triples quadrupole tandem mass spectrometry (RRLC-QqQ-MS/MS). Matrix-matched external calibrations were introduced to check matrix effects. Limits of quantification (LOQs) of pyridaben, dinotefuran, DN and UF in eggplant were 0.2, 0.2, 1.0 and 1.0 μg kg^-1, and 0.2, 0.2, 5.0 and 1.0 μg kg^-1 in soil, respectively. Limits of detection (LODs) of four pesticides were below 0.41 μg L^-1. The mean recoveries (n = 5) of these insecticides varied from 79.4% to 103%, and the relative standard deviations (RSDs) ranged from 2.1% to 15.3% at three levels. This method was applied to Chinese open-field samples from two representative locations, which were previously treated with these insecticides at the doses of 210-315 g a.i. ha^-1 twice or three times. The dissipations of pyridaben and dinotefuran in eggplant and soil followed first-order kinetics with the half-lives of 3.65-11.4 d. The residues of pyridaben and total dinotefuran (calculated as sum of dinotefuran parent, DN and UF) in eggplant were below 0.0311 mg kg^-1 at the pre-harvest interval (PHI, 7 d). Presently, no maximum residue limit (MRL) of pyridaben and dinotefuran in eggplant was recommended by China, Codex Alimentarius Commission (CAC) or European Union (EU). This study was important for evaluation of environmental fate and food safety of pyridaben and dinotefuran in eggplant ecosystems, and facilitated China to establish maximum residue limits (MRLs) of pyridaben and dinotefuran in eggplant.

Comparative toxicity and bioaccumulation of two dinotefuran metabolites, UF and DN, in earthworms (Eisenia fetida)

Dinotefuran, as the latest generation of neonicotinoid insecticide, has broad application prospects around the world. However, dinotefuran is easily metabolized and the two main metabolites are 1-methyl-3-(tetrahydro-3-furylmethyl) urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl) guanidium dihydrogen (DN). In the present study, the risks of UF and DN in soil on typical non-target species earthworm were investigated. In the same time, the degradation in soil and accumulation in earthworms of UF and DN were monitored. The present results showed that the toxicities of UF and DN were similar in their effect on earthworms and they were supertoxic pollutants to earthworms. The degradation trend in soil and accumulation trend in earthworms of UF and DN were consistent throughout the whole exposure period. At 1.0 mg/kg and 2.0 mg/kg, UF and DN could induce the excess production of ROS, resulting in oxidative stress effects in earthworm cells. The excess ROS induce changes in antioxidant enzyme activities, damage in biomacromolecules, and abnormal expression of function genes. The present results showed that UF and DN may have high risks for earthworms.

Dissipation behaviour, residue distribution and dietary risk assessment of tetraconazole and kresoxim-methyl in greenhouse strawberry via RRLC-QqQ-MS/MS technique

20% commercial suspension emulsion (SE) of (8% tetraconazole + 12% kresoxim-methyl), as a pre-registered product in China, was firstly investigated under Chinese greenhouse-field conditions. A MWCNTs-based QuEChERS method for simultaneous determination of tetraconazole and kresoxim-methyl in strawberry was developed and validated via RRLC-QqQ-MS/MS. On basis of this method, the dissipation behaviours, residue distributions and dietary risk probability of these fungicides in strawberry were further investigated for food safety. The dissipations of tetraconazole and kresoxim-methyl followed first-order kinetics with the half-lives of 8.0-18.2 days. The highest residues (HRs) of these fungicides in the supervised trials at the pre-harvest interval (PHI, 3 days) were below 0.8970mgkg^-1. The total national estimated daily intake (NEDI) of tetraconazole and kresoxim-methy in strawberry at the PHI 3day was 0.2784mg and 0.4031mg, respectively, based on Chinese dietary pattern and terminal residue distributions under good agricultural practices (GAP) conditions. The risk quotients (RQs) of tetraconazole and kresoxim-methy at PHI 3 days were below 82.7% and 1.6%, respectively, showing that the evaluated strawberry exhibited an acceptably low dietary risk to consumers. The current study could not only guide reasonable usage of the formulation, but also facilitate the setting of maximum residue limits (MRLs) of tetraconazole in strawberry.

Dissipation behavior and residue distribution of fluazaindolizine and its seven metabolites in tomato ecosystem based on SAX SPE procedure using HPLC-QqQ-MS/MS technique

Fluazaindolizine suspension concentrate (500gL^-1 SC), as a pre-commercialized product, was firstly investigated under open-field conditions. A sensitive method for simultaneous determination of fluazaindolizine and seven metabolites (IN-QEK31, IN-F4106, IN-A5760, IN-UJV12, IN-UNS90, IN-QZY47 and IN-TMQ01) was established and validated using HPLC-QqQ-MS/MS technique. The LOQs of these pollutants in tomato were 0.01mgkg^-1, and their recoveries were 81.1%-117% with the relative standard deviations (RSDs <11.8%). The dissipation behaviours of fluazaindolizine in soil followed first-order kinetics with the half lives of 4.6-32.4days, whilst the residues in plant were below its LOQ after 7days. The fluazaindolizine residues in soil were below 0.963mgkg^-1, based on root irrigation applications (50-75mg a.i. per plant) twice and pre-harvest interval (PHI, 3days), while the residues of IN-QEK31, IN-F4106 and IN-A5760 were below 3.9mgkg^-1, excluding other four metabolites (<0.01mgkg^-1). The residues of fluazaindolizine in tomato were below 0.01mgkg^-1, and IN-QEK31 remained 0.135mgkg^-1. The current study could not only guide reasonable usage of the formulation, but also facilitate the setting of residue definition and its maximum residue limits (MRLs) of fluazaindolizine in tomato.

Risk assessment and monitoring of dinotefuran and its metabolites for Chinese consumption of apples

Residues of dinotefuran and its metabolites, 1-methyl-3-(tetrahydro-3-furylmethyl)urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl)guanidine (DN), in apple were investigated using a "QuEChERS" (quick, easy, cheap, effective, rugged, safe) pretreatment and liquid chromatography-tandem mass spectrometry. Limits of detection (LODs) and quantification (LOQs) of dinotefuran, UF, and DN in apples were 0.011-0.960 and 0.037-3.200 μg/kg, respectively. The average recoveries of dinotefuran, UF, and DN in apple ranged from 70.0 to 83.6% with relative standard deviations less than 13%. A formulation of 20% water-dispersible dinotefuran granules was sprayed at 1-1.5-fold the recommended dose 3-4 times on apple trees. Total terminal residues of dinotefuran in apple were less than 2 mg/kg, which is the maximum residue limit (MRL) set by Japan. When following the recommended application guidelines, dinotefuran is unlikely to present significant health concerns to the Chinese population because the risk quotient (RQ) is less than 100%. This work could provide guidance for the safe use of dinotefuran and serve as a reference for the establishment of a maximum residue limit of dinotefuran in apple in China.

Biochemical and genetic toxicity of dinotefuran on earthworms (Eisenia fetida)

Dinotefuran is a third-generation neonicotinoid insecticide, that is considered promising due to its excellent properties. In the present work, the biochemical and genetic toxicity of dinotefuran on earthworms were evaluated at a series of environmental background concentrations. Meanwhile, the effective concentrations of dinotefuran in artificial soil during the entire exposure period were monitored. The present results showed that dinotefuran was stable in artificial soil, and its concentrations changed no more than 20% during the 28-d exposure. At 1.0 mg/kg and 2.0 mg/kg, dinotefuran induced excess generation of ROS, resulting in significant changes in antioxidant enzyme activities and functional gene expression. Moreover, lipids, proteins and nucleic acids were oxidized and damaged by the excess ROS induced by dinotefuran, resulting in serious destruction of the structure and function of cells. Additionally, the toxicity of dinotefuran showed obvious dose- and time-dependent effects. Therefore, we consider that dinotefuran may be a high-risk pollutant for earthworms.