Residue behavior and dietary risk assessment of six pesticides in pak choi using QuEChERS method coupled with UPLC-MS/MS

Recovery of green phenolic compounds from lignin-based source: Role of ferulic acid esterase towards waste valorization and bioeconomic perspectives

The production of chemicals/products so far relies on fossil-based resources with the creation of several environmental problems at the global level. In this situation, a sustainable and circular economy model is necessitated to mitigate global environmental issues. Production of biowaste from various processing industries also creates environmental issues which would be valorized for the production of industrially important reactive and bioactive compounds. Lignin acts as a vital part in biowaste composition which can be converted into a wide range of phenolic compounds. The phenolic compounds have attracted much attention, owing to their influence on diverse not only organoleptic parameters, such as taste or color, but also active agents for active packaging systems. Crop residues of varied groups, which are an affluent source of lignocellulosic biomass could serve as a renewable resource for the biosynthesis of ferulic acid (FA). FA is obtained by the FA esterase enzyme action, and it can be further converted into various tail end phenolic flavor green compounds like vanillin, vanillic acid and hydroxycinnamic acid. Lignin being renewable in nature, processing and management of biowastes towards sustainability is the need as far as the global industrial point is concerned. This review explores all the approaches for conversion of lignin into value-added phenolic compounds that could be included to packaging applications. These valorized products can exhibit the antioxidant, antimicrobial, cardioprotective, anti-inflammatory and anticancer properties, and due to these features can emerge to incorporate them into production of functional foods and be utilization of them at active food packaging application. These approaches would be an important step for utilization of the recovered bioactive compounds at the nutraceutical and food industrial sectors.

Risk assessment of multiple pesticide residues in Agrocybe aegerita: Based on a 3-year monitoring survey

The presence of pesticide residues in Agrocybe aegerita has raised an extensive concern. In this paper, based on a 3-year monitoring survey, the dietary exposure risks through A. aegerita consumption for different population subgroups were assessed using both deterministic and semi-probabilistic approaches under the best-case and the worst-case scenarios. Among the 52 targeted pesticides, 28 different compounds were identified in the concentration range of 0.005-3.610 mg/kg, and 87.4 % of samples contained one or more pesticide residues. The most frequently detected pesticide was chlormequat, followed by chlorfenapyr and cyhalothrin. The overall risk assessment results indicated extremely low chronic, acute, and cumulative dietary exposure risks for consumers. Using the ranking matrix, intake risks of pesticides were ranked, revealing endsoluran, chlorpyrifos, and methamidophos to be in the high-risk group. Finally, considering various factors such as the toxicity and risk assessment outcomes of each positive pesticide, use suggestions were proposed for A. aegerita cultivation.

Status and Perspective on Green Pesticide Utilizations and Food Security

Pesticides protect crops against pests, and green pesticides are referred to as effective, safe, and eco-friendly pesticides that are sustainably synthesized and manufactured (i.e., green chemistry production). Owing to their high efficacy, safety, and ecological compatibility, green pesticides have become a main direction of global pesticide research and development (R&D). Green pesticides attract attention because of their close association with the quality and safety of agricultural produce. In this review, we briefly define green pesticides and outline their significance, current registration, commercialization, and applications in China, the European Union, and the United States. Subsequently, we engage in an in-depth analysis of the impact of newly launched green pesticides on the environment and ecosystems. Finally, we focus on the potential risks of dietary exposure to green pesticides and the possible hazards of chronic toxicity and carcinogenicity. The status of and perspective on green pesticides can hopefully inspire green pesticide R&D and applications to ensure agricultural production and safeguard human and ecological health.

Residue and dietary intake risk assessment of lufenuron and chlorfenapyr and its corresponding metabolite in cabbage under field conditions

A simple, low-cost, and highly sensitive method using a modified QuECHERS procedure based on a liquid chromatography-tandem mass spectrometer (LC-MS/MS) was established to simultaneously quantify lufenuron and chlorfenapyr and the corresponding metabolite tralopyril in cabbage for the first time. On the basis of this method, terminal residue and dietary risk of lufenuron and chlorfenapyr in cabbage were investigated. The recoveries of lufenuron, chlorfenapyr, and tralopyril ranged from 88 to 110%, with relative standard deviation of less than 12.4%. The field trial results showed that at the pre-harvest interval (PHI) of 21 days, the terminal residues of lufenuron, chlorfenapyr, and tralopyril in the supervised trials were not higher than 0.02 mg/kg, and the highest detected residue levels of lufenuron, chlorfenapyr, and tralopyril were 0.047, 0.055, and <0.02 mg·kg-1 at 14-day pre-harvest respectively, which were lower than the maximum residue limits (MRLs) for cabbage established in China. For the dietary risk assessment, the national estimated daily intakes (NEDIs) as proportion of acceptable daily intakes (ADIs) were 80.4% and 29.9% for chlorfenapyr and lufenuron respectively indicating an acceptable dietary risk to Chinese population.

Environmental fate and safety analysis of methoxyfenozide application to control litchi and longan pests

Litchi and longan pests significantly affect crop yield and quality. Chemical prevention and control are very effective for production; therefore, it is crucial to study fate assessment and appropriate field efficacy before pesticide application on crops to appropriately assess the health and ecological risks linked with these agents. This study conducted Good Agricultural Practice (GAP) field trials and laboratory experiments to elucidate the dissipation, terminal residues, and efficacy of methoxyfenozide on litchi and longan in six locations throughout China. To detect methoxyfenozide residues on litchi and longan, a QuEChERS/UPLC-MS/MS-based method was designed. The initial methoxyfenozide levels in litchi and longan ranged from 2.21-2.86 to 0.83-0.95 mg kg-1 and indicated half-lives of 5.1-5.3 and 5.3-5.7 days, respectively. After 7 days of foliage treatment, the concentrations of terminal methoxyfenozide residue were 0.78-2.61 and 0.02-1.01 mg kg-1, which were less than the established maximum residue limit for methoxyfenozide in litchi and longan. The chronic (acceptable daily intake = 0.0055-0.0331%) dietary intake risk analysis for methoxyfenozide in longan and litchi indicated acceptable concentrations of terminal residue for the general population. Methoxyfenozide in litchi and longan was readily degraded in first-order kinetics models, the degradation rate on longan was higher than that on litchi, and their dietary risks were negligible to consumers. Two hundred forty grams per liter of methoxyfenozide suspension concentrate (SC) represents a highly efficacious insecticidal dose to control litchi and longan pests and indicates a significant application potential as it is rapidly degraded and linked with reduced post-treatment residue levels.

Dissipation, accumulation, distribution and risk assessment of fungicides in greenhouse and open-field cowpeas

Pesticide residues in cowpeas have raised worldwide concern. However, only a few studies have focused on pesticide accumulation and distribution in greenhouse and open-field cowpeas. Field trial results suggest that difenoconazole, dimethomorph, thifluzamide and pyraclostrobin dissipated faster in open fields (mean half-lives, 1.72-1.99 days) than in greenhouses (2.09-3.55 days); moreover, fungicide residues in greenhouse cowpeas were 0.84-8.19 times higher than those in the open-field cowpeas. All fungicides accumulated in the greenhouse and open-field cowpeas after repeated spraying. Fungicide residues in old cowpeas were higher than those in tender cowpeas, and residues in the upper halves of cowpea pods were higher than those in the lower halves. In addition, cowpeas distributed in the lower halves of the plants had higher fungicide residues. Our findings suggest that greenhouse cultivation contributed to the pesticide residues in cowpeas after repeated spraying, although the levels of dietary health risks remained acceptable under both cultivation scenarios.

Dissipation behaviours, residues, and health risk of six herbicides in sugar beets under field conditions

This study established a residue detection method based on the QuEChERS pre-treatment method and combined it with high-performance liquid chromatography-tandem mass spectrometry to test six herbicides (metamitron, clopyralid, desmedipham, phenmedipham, ethofumesate, and haloxyfop-p-methyl) in sugar beet plants, soil, and roots. The degradation dynamics and terminal residues of each herbicide in sugar beets were analysed. Finally, the dietary risks of various herbicides in sugar beets were evaluated based on the dietary structure of Chinese people, and the risk quotient values were below 100%. Using this detection method, all reagents exhibited good linearity (0.9724 ≤ R2 ≤ 0.9998), The limit of quantification (LOQ) ranged from 0.01 to 0.05 mg/L, the matrix effect ranged from -1.2% to -50%, the addition recovery rate ranged from 77.00% to 103.48%, and the relative standard deviation ranged from 1.61% to 16.17%; therefore, all indicators of this method met the residue detection standards. Under field conditions, the half-lives (t1/2) ranged about 0.65 ∼ 2.96 d and 0.38 ∼ 27.59 d in sugar beet plants and soil, respectively. All herbicides were easily degraded in sugar beet plants and soil (t1/2 < 30 d). The terminal residue amounts in the beet plants, soil, and roots ranged from < LOQ to 0.243 mg/kg. The dietary risk assessment of each pesticide was conducted based on the residual median of the terminal residues and the highest residual values on the edible part of the beetroot. The chronic exposure risk quotient (RQc) and acute exposure risk quotient (RQa) values were < 100%, indicating that the residue of each pesticide in beetroot posed low risks to consumers in China at the recommended dosage.

Residue behaviour and health risk assessment of chlorpyrifos and mancozeb in apple fruits and soil

Mancozeb residue estimation was done using second derivative ultraviolet spectroscopy by Shimadzu ultraviolet-visible spectrophotometer, and chlorpyrifos was estimated by QuEChERS technique using GC-FPD. The persistence for chlorpyrifos was carried out at two locations, and for mancozeb, persistence studies were carried out at four locations. Initial deposits of mancozeb on apple fruits ranged from 1.33 to 1.63 mg/kg at the recommended dose and from 2.55 to 3.26 mg/kg at double the recommended dose at all four locations. Chlorpyrifos residues in apple fruits had an initial deposit of 0.94-0.99 mg/kg at recommended dose and 1.75-1.92 mg/kg at double the recommended dose. Mancozeb residues in apple fruit were below the detection limit (BDL) after 20 days at recommended dose and after 25 days at double the recommended dose at two locations, while mancozeb residue at the other two locations and the residues of chlorpyrifos at all locations reached BDL after 15 and 20 days at recommended and double the recommended doses, respectively. Half-life of mancozeb varied from 3.07 to 4.02 days at recommended dose and from 3.30 to 4.32 days at double the recommended dose, whereas chlorpyrifos residues dissipated to half their initial concentration on 2.33-2.35 days at recommended dose and 2.89-2.90 days at double the recommended dose. The soil samples showed no presence of residues of chlorpyrifos and mancozeb at harvest. The risk assessment revealed that hazard quotient for the intake of mancozeb was in the range of 0.06-0.13% and 0.20-0.44% for rural and urban population, while for the intake of chlorpyrifos, hazard quotient was in the range of 0.10-0.12% for rural population and 0.33-0.38% for urban population, and theoretical maximum dietary intake (9.67 × 10-5 mg/person and 3.18 × 10-4 mg/person for rural population and urban population in case of mancozeb and 3.22 × 10-5 mg/person and 1.06 × 10-4 mg/person for rural population and urban population in case of chlorpyrifos) was also found to be less than maximum permissible intake (1.38 mg/kg for mancozeb and 0.60 mg/kg for chlorpyrifos). The results of risk assessment thereby indicated that apple consumption does not pose a risk to human health.

Dissipation behavior and dietary risk assessment of cyclaniliprole and its metabolite in cabbage under field conditions

Cyclaniliprole, a novel diamide insecticide, can successfully control Spodoptera litura (Fabricius, 1775) in cabbage. Understanding the residual level of cyclaniliprole in crops and the risk related to its dietary intake is imperative for safe application. Here, we established a simplified, sensitive method for simultaneous analysis of cyclaniliprole and its metabolite NK-1375 (3-bromo-2-((2-bromo-4H-pyrazolo[1,5-d]pyrido[3,2-b]-[1,4]oxazin-4-ylidene)amino)-5-chloro-N-(1-cyclopropylethyl)benzamide) in cabbage by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to investigate their dissipation behavior and residual characteristics. Cyclaniliprole showed rapid dissipation in cabbage and had a half-life of 1.8-2.7 days. The highest residue of total cyclaniliprole (sum of cyclaniliprole and NK-1375) in cabbage from different pre-harvest intervals (3 and 5 days) was 0.25 mg/kg. Our results confirmed the generally low dietary risk quotient of cyclaniliprole (0.243-1.036%) among different age and gender groups in China. Therefore, cyclaniliprole did not pose an unacceptable risk to consumers. This study contributes to setting cyclaniliprole maximum residue limit in cabbage by assessing its dissipation fate and food safety risks.

Translocation and dissipation of thiamethoxam applied by root irrigation in tomato plant-soil system

Thiamethoxam (TMX) has been registered for use on a wide range of crops due to its versatile application methods, however, there is limited literature evaluating the residue behaviors of TMX applied through root irrigation. In this study, the uptake and translocation of TMX, its degradation to clothianidin (CLO), and dissipation in the tomato plant-soil system were conducted. TMX applied by root irrigation was transferable within the tomato plant, including stems, leaves, and fruits at different heights. TMX concentrations in the four sections of stems were ordered as Clower > Cmid > Cupper > Ctop, while in the leaves were ordered as Ctop > Cupper > Cmid > Clower. The degradation product CLO was detected in the tomato plant, and concentrations of CLO were even higher than those of TMX in the leaves. The translocation factor (TF) of TMX in the same section generally followed the order of TFleaf > TFstem > TFfruit. Residues of TMX and CLO in tomato on 7 days after application were below maximum residue limits (MRLs) in China and Codex Alimentarius Commission (CAC). This study promotes the evaluation of TMX applied through root irrigation for use in the tomato system from a dietary safety perspective.

Quantitative analysis of the minimum days of dietary survey to estimate dietary pesticide exposure: Implications for dietary pesticide sampling strategy

Populations are exposed to pesticides through diet on a daily basis. However, there is no research guiding how to evaluate dietary pesticide exposure, and researchers used 1-day, 3-days, 7-days or even longer dietary survey to evaluate without any consensus. It is important for dietary pesticide evaluation to identify the minimum survey days. To increase knowledge of this, a data combination was applied between a two-wave consecutive repeated-measures study in Baoding City and the Fifth China Total Diet Study. Further policy consistency on pesticides were evaluated to explain its credibility. We computed the sensitivity and specificity to evaluate how well different days of dietary survey classify participants with high exposure, and calculated the minimum days required to estimate the participant-specific mean at different acceptable error range. With 1 day of dietary survey, the classification sensitivity was low (<0.6) for total HCH, endosulfan, chlordane, cyhalothrin, allethrin, and prallethrin; that for the other pesticides was high sensitivity (≥0.6). Sensitivity increased as the number of days increased, and the maximum marginal sensitivity increase (≥0.039) occurred from 1 to 2 days for all pesticides except phenothrin, whose maximum marginal sensitivity increase (0.042) occurred from 2 to 3 days. The specificity increased gradually from 0.8 to 0.9 from 1 to 7 days. Under the acceptable error range of 0.5%, 3-28 days were required for participant-specific mean estimation and 1-7 days were required when acceptable error range was shrunk in 1%. Only 1 day was enough if 5% error range was acceptable. In conclusion, 3 days in the study period was cost-effective to distinguish high exposure group, and it rose to 7 when estimating participant-specific mean from a conservative perspective. This study can serve as a reference to determine the minimum survey days for epidemiological studies employing dietary surveys.

Residue analysis and dietary risk assessment of thiamethoxam, flonicamid and their metabolites in cucumber under field conditions in China

Thiamethoxam and flonicamid are two representative insecticides of neonicotinoids which are used to treat cucumber aphids, causing food safety and human health problems. A 60% thiamethoxam-flonicamid commercial mixture water dispersible granule (WDG) is being prepared for registering in China, so it is essential to investigate the residue levels of these neonicotinoids and their metabolites in cucumber and evaluate the dietary risks of these insecticides. We developed a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method combined with high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of thiamethoxam and its metabolite clothianidin, flonicamid and its metabolites 4-trifluoromethylnicotinic acid (TFNA), 4-trifluoromethilnicotinamide (TFNA-AM), 4-(trifluoromethyl) nicotinol glycine (TFNG) in cucumber. Method validation indicated good selectivity, linearity (r ≥ 0.9996), accuracy (recoveries of 80-101%), precision (relative standard deviations (RSD) ≤ 9.1%), sensitivity (limits of detection (LOD), 0.28-1.44 × 10^-3 mg/L; limits of quantification (LOQ), 0.01 mg/kg) and minor matrix effect (ME) ( ≤|± 5%|). In the terminal residue trials under good agricultural practice (GAP) conditions, the residue levels of six analytes in cucumber samples were ˂0.01-0.215 mg/kg after application trice with an interval of 7 days based on pre-harvest interval (PHI) of 3 days under the high recommended dosage of 54 g active ingredient/ha (g a.i./ha). Relevant toxicological, residual chemistry parameters and dietary consumption of the residents were applied to assess the potential risk of dietary exposure. The chronic and acute dietary exposure assessment risk quotient (RQ) values were less than 1. The above results indicated that the potential dietary intake risk of this formulation was negligible to consumers.

Fungicide Dissipation Kinetics and Dietary Exposure Risk Assessment in Squash Fruit and Leaf

The dissipation behavior and dietary exposure risk assessment of four fungicides (dimethomorph, mandipropamid, myclobutanil, and metalaxyl) was performed in fruits and leaves of squash grown under greenhouse conditions. Squash fruit and leaf samples were randomly collected at 0, 3, 5, 7, and 14 days after the last pesticide application. Analysis was performed using ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). The quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was used for sample preparation. Recovery rates at two spiked levels (0.01 and 0.1 mg/kg) were found to be in the range of 76.4%-101.9% for the analyzed pesticides and their relative standard deviations were ≤4%. Pesticide half-lives were 2.1 and 4.9 days for dimethomorph, 4.6 and 8.1 days for mandipropamid, 4.7 and 8.2 days for myclobutanil, and 2.7 and 5 days for metalaxyl in squash fruit and leaf, respectively. Regarding the total surveyors, hazard quotient values for squash fruit and leaf were ≤1.03 × 10^-3 and ≤2.39 × 10^-3, respectively. These values in the case of true consumers were ≤3.14 × 10^-3 and ≤3.91 × 10^-1, respectively.

Development of Acid Hydrolysis-Based UPLC–MS/MS Method for Determination of Alternaria Toxins and Its Application in the Occurrence Assessment in Solanaceous Vegetables and Their Products

In this work, we proposed an acid hydrolysis-based analytical method for the detection of Alternaria toxins (ATs) in solanaceous vegetables and their products with solid-phase extraction (SPE) and ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). This study was the first to reveal that some compounds in the eggplant matrix bind to altenusin (ALS). Validation under optimal sample preparation conditions showed that the method met the EU criteria, exhibiting good linearity (R2 > 0.99), matrix effects (−66.6–−20.5%), satisfying recovery (72.0–107.4%), acceptable precision (1.5–15.5%), and satisfactory sensitivity (0.05–2 µg/kg for limit of detection, 2–5 µg/kg for limit of quantification). Out of 393 marketed samples, only 47 samples were detected, ranging from 0.54–806 μg/kg. Though the occurrence ratio (2.72%) in solanaceous vegetables could be negligible, the pollution status in solanaceous vegetable products was much more serious, and the incidences were 41.1%. In the 47 contaminated samples, the incidences were 4.26% for alternariol monomethyl ether (AME), 6.38% for alternariol (AOH) and altenuene (ALT), 42.6% for tentoxin (TEN), and 55.3% for tenuazonic acid (TeA).

Method Validation for Multi-Pesticide Residue Determination in Chrysanthemum

The chrysanthemum can be consumed in various forms, representing the "integration of medicine and food". Quantitative analysis of multi-pesticide residues in chrysanthemum matrices is therefore crucial for both product-safety assurance and consumer-risk evaluation. In the present study, a simple and effective method was developed for simultaneously detecting 15 pesticides frequently used in chrysanthemum cultivation in three matrices, including fresh flowers, dry chrysanthemum tea, and infusions. The calibration curves for the pesticides were linear in the 0.01-1 mg kg^-1 range, with correlation coefficients greater than 0.99. The limits of quantification (LOQs) for fresh flowers, dry chrysanthemum tea, and infusions were 0.01-0.05 mg kg^-1, 0.05 mg kg^-1, and 0.001-0.005 mg L^-1, respectively. In all selected matrices, satisfactory accuracy and precision were achieved, with recoveries ranging from 75.7 to 118.2% and relative standard deviations (RSDs) less than 20%. The validated method was then used to routinely monitor pesticide residues in 50 commercial chrysanthemum-tea samples. As a result, 56% of samples were detected with 5-13 pesticides. This research presents a method for the efficient analysis of multi-pesticide residues in chrysanthemum matrices.

Development of a Modified QuEChERS Method Coupled with LC-MS/MS for Determination of Spinetoram Residue in Soybean (Glycine max) and Cotton (Gossypium hirsutum)

An analytical method for the quantitative determination of the insecticide spinetoram in cotton and soybean was established and validated using liquid chromatography tandem mass spectrometry (LC-MS/MS). Spinetoram is the mixture of two spinosyns, 3′-O-ethyl-5,6-dihydro spinosyn J and 3′-O-ethyl spinosyn L. The method involves extraction with ethyl acetate followed by dispersive solid phase extraction (dSPE) clean-up with primary secondary amine (PSA), C18 and graphitised carbon black (GCB). The final quantitation of spinetoram was done by using LC-MS/MS with positive electrospray ionization. The method was reproducible (Horwitz ratio (HorRat) < 0.5 at 25 ng g−1) and validated by the analysis of samples spiked at 25, 50 and 100 ng g−1 in soybean, cotton and soil. The recoveries of spinosyns were found to be more than 85% when spiked at different levels. The identities of spinosyns were confirmed by using the ion ratio. A field dissipation study was conducted in soybean and cotton to find out the environmental fate of spinetoram, and samples were analysed following the proposed analytical method. Both isomers were found to be dissipated quickly. The pre-harvest interval of spinetoram was calculated in different substrates.

Residue, biotransformation, risk assessment and withdrawal time of enrofloxacin in red swamp crayfish (Procambarus clarkii)

Crayfish is a very popular aquatic food in many countries, and enrofloxacin (ENR) and ciprofloxacin (CIP) was the most frequently detected in aquatic products. However, limited information is available on the residue characterization, biotransformation rate and withdrawal period (WT) of ENR and CIP in crayfish and health risk via consumption of ENR and CIP remained crayfish. Herein, a comprehensive investigation was conducted to study residue depletion, biotransformation, ingestion risk, and WT of ENR and its predominate metabolite CIP in crayfish following different routes with repeated doses. The results showed that the elimination half-life (T_1/2) of target compounds in crayfish were all in order of hepatopancreas > muscle > gill, and the order of T_1/2 in different crayfish tissues were intramuscular (IM) route > oral (PO) treatment > immersion (IMMR) administration. The biotransformation rates from ENR to CIP varied from 0.75% to 3.45% in crayfish tissues following different exposure routes. The high dietary risk (RQ > 1) consuming muscle and hepatopancreas of ENR and CIP remained crayfish occurred at early after different administrations. WT is the key to control the drug residue risk, and the longest WT of marker residue of ENR in crayfish was calculated to be 51 d (1275 °C-day).

Residue Behavior of Methoxyfenozide and Pymetrozine in Chinese Cabbage and Their Health Risk Assessment

Methoxyfenozide and pymetrozine are used for pest control in the cultivation of Chinese cabbage. This has raised concerns in recent years due to health risks. Therefore, this study aimed to determine the residual concentrations of pesticides in the target crop and associated health risks. The dynamics and influence of environmental factors on the dissipation of methoxyfenozide and pymetrozine residues in Chinese cabbage were investigated. Analyses were performed using a modified QuEchERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) and an optimized high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The observed half-lives of methoxyfenozide and pymetrozine in cabbage samples ranged between two sampling seasons: in May−June, half-lives of methoxyfenozide and pymetrozine were 1.20 days and 1.89 days, respectively; during October−November, half-lives of methoxyfenozide and pymetrozine were 11.8 and 2.80 days, respectively. Meanwhile, a negative Spearman correlation was found between the residual concentrations and temperature (p < 0.01). This indicates that higher temperatures resulted in higher dissipation rates for methoxyfenozide and pymetrozine, suggesting that these pesticides degraded faster at higher temperatures. Additionally, higher pesticide residues in Chinese cabbage during low-temperature seasons resulted in higher risk quotients (RQ) (RQ > 1) for both analyzed compounds, which suggests that the effect of temperature on pesticide degradation needs to be considered as an essential factor while setting up the maximum residue limits (MRL).

Dissipation behavior, residue transfer, and safety evaluation of chlorantraniliprole and indoxacarb during tea growing and brewing by ultrahigh-performance liquid chromatography-tandem mass spectrometry

A reliable and simple analytical method was developed and validated to simultaneously determine chlorantraniliprole and indoxacarb in tea using ultrahigh-performance liquid chromatography-tandem mass spectrometry. The average recoveries of chlorantraniliprole were in the range of 86-110%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 1.9 to 8.4% and from 2.4 to 8.8%, respectively. The average recoveries of indoxacarb were in the range 81-105%, with the precision of intraday (n = 5) and interday (n = 15) ranging from 2.0 to 9.8% and from 2.7 to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. The results based on the supervised field trials showed that chlorantraniliprole and indoxacarb in two tea samples followed first-order kinetics models with half-lives of 2.2-4.7 days and 2.5-3.5 days, which could be regarded as a moderately degrading pesticide. The terminal residues of chlorantraniliprole and indoxacarb in made tea were below 6.7 and 4.5 mg/kg, respectively, lower than their corresponding maximum residue limits (MRLs) established by several major countries and organizations (50 and 5 mg/kg). The leaching rates of chlorantraniliprole and indoxacarb during the tea brewing ranged from 4.78 to 12.62% and 4.13 to 10.67%, respectively. The chronic intake risk quotient (RQc) values for chlorantraniliprole and indoxacarb were 0.24% and 35.10%, while the acute dietary risk assessment (RQa) value of indoxacarb was 5.8%, which were all much lower than 100%. The results in the present study indicated that the health risk posed by the chlorantraniliprole and indoxacarb mixture pesticides was negligible in tea for consumers at the recommended dosages.

HPLC-MS/MS analysis of zinc-thiazole residues in foods of plant origin by a modified derivatization-QueChERS method

Zinc-thiazole is a new fungicide that was independently developed in China and has a high efficiency and low toxicity. A modified derivatization method was established to measure zinc-thiazole in foods of plant origin. Zinc-thiazole decomposed into 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) under alkaline conditions, and the AMT was extracted with acidic acetonitrile (pH = 3). The AMT was quantitated by HPLC-MS/MS, and then the amount of zinc-thiazole residue was calculated. Good linearity (R² > 0.9997) was obtained in 0.001-1 mg/L. The limit of quantification of zinc-thiazole was 0.02 mg/kg in peaches, grapes, brown rice and soybeans. A qualified accuracy (recoveries of 75%-90%) and precision (RSD of 1%-5%) were obtained at three fortified levels. This method was applied to peach samples collected from farmland, and the zinc-thiazole residues complied with the residue limits. In the future, this method could be used to analyze residues and in the risk assessment of metal-thiazole fungicides.

Dissipation behaviour, residue analysis, and dietary safety evaluation of chlorfenapyr on various vegetables in China

Chlorfenapyr has been widely used in recent years to control a variety of pests on fruit and vegetables. Cabbage, leek, asparagus, and chive are four of the most common green foods consumed word wide; their pesticide residue issues have also received more attention. Therefore, studies on the residue analysis, degradation evaluation and dietary risk assessment based on the complete residue definition of chlorfenapyr on these four vegetables were essential and urgently needed. A reliable analytical method was developed and applied to simultaneously determine the content of chlorfenapyr and its metabolite tralopyril residues on the four vegetables. Recoveries were satisfactory (84%-110% for chlorfenapyr; 83%-106% for tralopyril) at a spiked level of 0.01-1 mg/kg, with intraday precision (n = 5) and interday precision (n = 15) ranging from 1.6% to 8.9% and from 2.4% to 9.1%, respectively. The limits of quantification (LOQs) were all 0.01 mg/kg. On the basis of supervised field trials, the degradation half-lives of chlorfenapyr were 1.2-9.8 days. Chlorfenapyr rapidly degraded on asparagus, but persisted much longer on chive. The terminal concentration of chlorfenapyr residues varied from <0.01 to 0.84 mg/kg. Additionally, the risk quotients (RQs) ranged from 4.7% to 13.8%, suggesting that chlorfenapyr had a negligible risk for chronic dietary intake of these crops. This study was thus significant in evaluating the degradation rate and quality safety of chlorfenapyr on various vegetables and promoted the development of maximum residue limits.

Residue, dissipation and dietary intake risk assessment of tolfenpyrad in four leafy green vegetables under greenhouse conditions

•

A QuEChERS-GC–MS/MS method was used to detect tolfenpyrad in leafy green vegetables.

•

Half-lives of tolfenpyrad were 2.0–6.8 d in greenhouse-grown leafy green vegetables.

•

PHI of tolfenpyrad was suggested as 21 d in BCL and 28 d in BBL, SOL and LSL.

•

The potential health risk of tolfenpyrad was acceptable in leafy green vegetables.

A novel and accurate analytical method for the determination of tolfenpyrad in four leafy green vegetables, Brassica bara L., Spinacia oleracea L., Lactuca sativa L. and Brassica chinensis L., was developed and applied to investigate the residue distribution and dietary risk under greenhouse conditions. The established approach was determined to be adequate, with recoveries of 79.2%–92.9% and relative standard deviations < 8%. Tolfenpyrad dissipated relatively rapidly in four leafy green vegetables. Terminal residues of tolfenpyrad were below 0.5 mg/kg (maximum residue limit for Brassica bara L. set by China) in leafy green vegetables collected 28 d after the last application. Due to risk quotient values < 100%, the residue levels of tolfenpyrad in leafy green vegetables collected 21 days after the last application were deemed safe for consumers. The results provide field data for the reasonable use and dietary risk assessment of tolfenpyrad in leafy green vegetables.

Dissipation of imidacloprid and its metabolites in Chinese prickly ash (Zanthoxylum) and their dietary risk assessment

Dissipation of imidacloprid (IMI) and its metabolites (urea, olefin, 5-hydroxy, guanidine, 6-chloronicotinic acid) in Chinese prickly ash (CPA) was investigated using QuEChERS combined with UPLC-MS/MS. Good linearity (r² ≥0.9963), accuracy (recoveries of 71.8-104.3%), precision (relative standard deviations of 0.9-9.4%), and sensitivity (limit of quantification ≤0.05 mg kg^-1) were obtained. After application of IMI at dosage of 467 mg a.i. L^-1 for three times with interval of 7 d, the dissipation dynamics of IMI in CPA followed first-order kinetics, with half-life of 6.48-7.29 d. IMI was the main compound in CPA, followed by urea and guanidine with small amounts of olefin, 5-hydroxy, and 6-chloronicotinic acid. The terminal residues of total IMI and its metabolites at PHI of 14-21 d were 0.16-7.80 mg kg^-1 in fresh CPA and 0.41-10.44 mg kg^-1 in dried CPA, with the median processing factor of 3.62. Risk assessment showed the acute (RQa) and chronic dietary risk quotients (RQc) of IMI in CPA were 0.020-0.083% and 0.052-0.334%, respectively. Based on the dietary structures of different genders and ages of Chinese people, the whole dietary risk assessment indicated that RQc was less than 100% for the general population except for 2- to 7-year-old children (RQc of 109.9%), implying the long-term risks of IMI were acceptable to common consumers except for children.

Dissipation behavior and dietary risk assessment of pyridaben in open field strawberries and cucumber under Egyptian cultivation conditions

Pyridaben, an inhibitor of mitochondrial electron transport at complex I, is authorized in Egypt as an insecticide/acaricide for strawberries and cucumbers; thus the investigation of residues in the final consumed product is essential as to ensure consumer safety and trade barriers. Therefore, residue trials were conducted according to the in force and more critical Good Agricultural Practices (GAPs) as to investigate the dissipation rate of the compound on both crops and the terminal residues in the final products. Results showed that the residue decline fits a first-order decay process with calculated half-lives of 1 and 6.4 days for cucumbers and strawberries, respectively. Dietary risk assessment was performed based on the risk quotients (RQ) method and the EFSA PRIMo model demonstrating that the dietary exposure to pyridaben residues from cucumber and strawberry consumption, applied either according to the in force or more critical GAPs, does not pose unacceptable health risk to Egyptian and European consumers.

Investigation of pesticide residues in peach and nectarine sampled from Çanakkale, Turkey, and consumer dietary risk assessment

The present study was conducted to investigate pesticide residues on peach and nectarine. For method verification, samples were spiked at 0.1, 1.0, and 10.0 times of maximum residue limit (MRL) for each pesticide. The Quick-Easy-Cheap-Efficient-Rugged-Safe (QuEChERS)-liquid chromatography/tandem mass spectrometry detection revealed that limit of quantifications (LOQs) of pesticides were below the MRL. The overall recovery was 113.51% with relative standard deviation (RSD) of 17.33% for peach and 113.61% with RSD of 11.44% for nectarine. These figures were within the Directorate-General for Health and Food Safety (SANTE) recovery limits (60-140%) and the values specified for the repeatability (RSD ≤ 20%). Samples were collected from 5 different stands at Çanakkale open markets for 12 weeks. None of the residues was not ≥ MRL in any samples. Maximum levels of 567.80 and 322.10 μg/kg boscalid were detected in peach and nectarine, respectively, corresponding approximately 1/10 and 1/15 of the MRL. Maximum levels for tebuconazole were about 1/12 and 1/10 of the MRL for peach (47.53 μg/kg) and nectarine (56.90 μg/kg), respectively. Chlorpyrifos residues of all samples were below LOQ. According to our findings and the World Health Organisation Guideline, chronic exposure levels of pesticides were low and there is no risk to human health in terms of 3 pesticides.

Determination of 1-methylcyclopropene residues in vegetables and fruits based on iodine derivatives

An innovative method was established for the determination of 1-methylcyclopropene (1-MCP) in vegetables and fruits. Due to its small molecular weight and low boiling point, it was difficult to obtain quantitative analysis for 1-MCP, especially at the residual level. In this work, based on its iodine derivatives, 1-MCP was derived to 1,2-diiodo-1-methylcyclopropane, which was much easier for trace and accurate chromatographic analysis. During the method validation, the method validation results were satisfactory in terms of linearity (4 ~ 400 µg/L, and R² ≥ 0.959), matrix effect (-89% ~ -13%), accuracy (80 ~ 100%), sensitivity (limits of quantification, 5 μg/kg) and precision (relative standard deviations ≤ 19%), which was in accordance with the Chinese guidelines for the testing of pesticide residues in crops. Finally, the proposed analytical method was used to monitor the 1-MCP residue levels in commercially available samples, and all the values were below 5 µg/kg, which satisfied the EU or Japan MRLs of 1-MCP.