Ecotoxicity threshold values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide in fresh and marine waters: Part 1. Derivation of threshold values.

Pesticide active ingredients are frequently detected in the rivers, creeks, wetlands, estuaries, and marine waters of the Great Barrier Reef (GBR) region and are one of the main contributors to poor water quality. Pesticide concentrations detected in the environment through water quality monitoring programs can be compared against estimates of ecologically "safe" concentrations (i.e., water quality guidelines) to assess the potential hazard and risk posed to aquatic ecosystems. Water quality guidelines are also required to estimate the aquatic risk posed by pesticide mixtures, which is used for the Reef 2050 Water Quality Improvement Plan pesticide target. Seventy-four pesticide active ingredients and their degradates are frequently detected in GBR catchment waterways, however many do not have water quality guidelines in the Australian and New Zealand Guidelines for Fresh and Marine Water Quality. The current study derives ecotoxicity threshold values (ETVs) as unendorsed guideline values for active ingredients in two fungicides (4-hydroxychlorothalonil (fungicide degradate) and carbendazim) and two insecticides (dimethoate and methoxyfenozide) that are commonly detected in GBR catchment waterways. The proposed ETVs have been derived using species sensitivity distributions, as recommended in the Australian and New Zealand nationally endorsed method for deriving water quality guidelines for aquatic ecosystem protection. Four ETVs were derived for each chemical with values that should theoretically protect 99, 95, 90 and 80 % of species (i.e., PC99, PC95, PC90, PC80, respectively). The PC99 and PC95 values for 4-hydroxychlorothalonil, carbendazim, dimethoate and methoxyfenozide were 0.49 µg/L and 4 µg/L, 0.029 µg/L and 0.45 µg/L, 0.11 µg/L and 5.8 µg/L and 0.19 µg/L and 2 µg/L, respectively. The ETVs will be used in an ecological hazard and risk assessment across GBR waterways in part two of this study. The ETVs can also be used to assess potential risk across Australia and internationally where monitoring data are available.

Kinetic and Mechanistic Modelling of Pyrimethanil Fungicide Adsorption onto Soils of Varying Physico-chemical Properties.

Pesticide transport in the environment is impacted by the kinetics of its adsorption onto soil. The adsorption kinetics of pyrimethanil was investigated in ten soil samples of varying physicochemical properties. The highest adsorption was in the soil having the maximum silt and CaCO3 contents, pH and electrical conductance but the lowest amorphous Fe oxides and CaCl2 extractable Mn. Pseudo-second order kinetics and intra-particle diffusion model best accounted the adsorption kinetics of pyrimethanil. The equilibrium adsorption estimated by pseudo-second order kinetics (q02) was significantly and positively correlated with CaCl2 extractable Cu content (r = 0.709) while rate coefficient (k02) had a negative correlation with crystalline iron oxides content (r = -0.675). The intra-particle diffusion coefficient (ki.d.) had inverse relationship with CaCl2 extractable Mn content in soils (r = -0.689). FTIR spectra showed a significant interaction of pyrimethanil with micronutrient cations. Adsorption kinetic parameters of pyrimethanil could be successfully predicted by soil properties. The findings may help to evolve fungicide management decisions.

Combination of Capture-SELEX and Post-SELEX for procymidone-specific aptamer selection and broad-specificity aptamer discovery, and development of aptamer-based lateral flow assay.

BACKGROUND: Due to its wide application, procymidone has become one of the pesticides with high detection rates in supervision and sampling. Therefore, it is necessary to establish a rapid and efficient method for the detection of procymidone. However, an important bottleneck restricting the development of rapid detection methods of procymidone is that its specific recognition elements are rarely reported. In this work, Capture-SELEX and post-SELEX were used in aptamer screening, and the obtained aptamers were used to construct an aptamer-based lateral flow assay (LFA). RESULTS: Firstly, a specific aptamer Seq15 was obtained for procymidone by Capture-SELEX, and its dissociation constant (Kd) was 24.22 nM. Secondly, post-SELEX was used to analyze and modify Seq15 to improve its performance, and the Kd of the truncated sequence Seq15-2 was 21.28 nM. In addition to this, the broad-specificity aptamer Seq17-1 was obtained via post-SELEX. Seq17-1 could broadly recognize dicarboximide fungicides (procymidone, iprodione, chlozolinate, dimethachlon and vinclozolin) and their metabolic derivative (3,5-dichloroaniline). Finally, the specific aptamer-based LFA of procymidone was constructed, and the limit of detection (LOD) was 0.79 ng/mL. Meanwhile, the LODs of dicarboximide fungicides and their metabolic derivative were 0.62, 0.64, 0.71, 0.69, 0.64 and 0.66 ng/mL, respectively. The above LFAs were highly specific and stable, and had been successfully used for the detection of vegetable samples. SIGNIFICANCE: Under the combination of Capture-SELEX and Post-SELEX, this study not only provides specific recognition elements for rapid detection of procymidone, but also provides new ideas for the discovery of broad-specificity aptamers. Combining broad-specificity primary detection and single-specificity quantification, a composite aptamer-based LFA detection platform has been developed, which significantly improves detection efficiency.

Quantitative determination of prothioconazole in wheat grain, soybean, and pond water based on a polyclonal antibody.

Prothioconazole and its metabolite are considered a potential threat to human health and environmental safety. Thus, the development of a sensitive and rapid detection method for prothioconazole is crucial to ensure the safety of agricultural products. In this study, a new hapten of prothioconazole was designed and synthesized, and a selective polyclonal antibody with high affinity against prothioconazole was produced, which was obtained from immunized New Zealand white rabbits. Based on the polyclonal antibody, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and indirect competitive chemiluminescence enzyme immunoassay (ic-CLEIA) were developed for detecting prothioconazole pesticides. Under optimized experimental conditions, the limit of quantification (LOQ) values for ic-CLEIA and ic-ELISA were 1.8 and 10.7 ng mL-1, respectively. The results demonstrated that the sensitivity (LOQ) achieved by ic-CLEIA was more than five times higher compared to that obtained with ic-ELISA. In addition, the recoveries obtained by adding standard prothioconazole to wheat grain, soybean, and pond water samples were in the range of 81.9 to 104.7% for ic-ELISA and 89.0 to 118.0% for ic-CLEIA.

Analytical challenges related to the measurement of chlorothalonil in serum in the perspective of human biomonitoring studies.

Chlorothalonil (CTN) is a popular fungicide widely used in the world. However, its determination in serum samples is highly challenging, preventing a reliable investigation of human CTN internal exposure. We first investigated CTN's behaviour all along this analytical process on spiked serum samples. We used a radiolabelled 14C-CTN standard to monitor CTN in spiked serum samples and observed (1) a complete degradation of CTN in deproteinised serum samples after 4 h of contact; (2) a strong interaction between serum proteins and CTN by-products, with only 20 % of the radioactivity found to be extractable after 24 h of contact and (3) a slightly improved stability of CTN in serum following a first step of acidification or EDTA addition to samples. Using liquid chromatography coupled to high resolution mass spectrometry, 4-hydroxy-2,5,6-trichloroisophthalonitrile (HCTN) was identified as the major serum by-product of CTN. A protocol was developed to monitor both extractable CTN and HCTN from serum. This method was implemented on 36 human adult serum samples from the French "Esteban" Cohort. No free CTN was identified in these serum samples. Conversely, HCTN was detected in all samples at concentrations around 15 ± 2 ng mL-1, corresponding to the extractable fraction of CTN. Thus, HCTN may constitute a relevant biomarker of human internal exposure. Of note, the potential CTN contamination during blood collection could also be a source of HCTN detection in serum samples. Finally, blood sampling in EDTA tubes would seem more appropriate than in dry tubes for any future internal exposure studies on CTN.

Development of a Portable Cell-Based Biosensor for the Ultra-Rapid Screening for Boscalid Residues in Lettuce.

Fungal plant pathogens have posed a significant threat to crop production. However, the large-scale application of pesticides is associated with possible risks for human health and the environment. Boscalid is a widely used fungicide, consistently implemented for the management of significant plant pathogens. Conventionally, the detection and determination of boscalid residues is based on chromatographic separations. In the present study, a Bioelectric Recognition Assay (BERA)-based experimental approach combined with MIME technology was used, where changes in the electric properties of the membrane-engineering cells with anti-boscalid antibodies were recorded in response to the presence of boscalid at different concentrations based on the maximum residue level (MRL) for lettuce. The membrane-engineering Vero cells with 0.5 µg/mL of antibody in their surface were selected as the best cell line in combination with the lowest antibody concentration. Furthermore, the biosensor was tested against another fungicide in order to prove its selectivity. Finally, the BERA cell-based biosensor was able to detect the boscalid residue, below and above the MRL, in spiked lettuce leaf extracts in an entirely distinct and reproducible manner. This study indicates that the BERA-based biosensor, after further development and optimization, could be used for the routine, high-throughput detection of boscalid residue in lettuce, and not only that.

Determination of ethylene-bis-dithiocarbamates and their degradation product ethylenethiourea in dry herbs by UHPLC-MS/MS.

Dithiocarbamates are a class of fungicides widely used in many countries. In this study, methods for determining the ethylene-bis-dithiocarbamate (EBDC) subclass, and their degradation product ethylenethiourea (ETU) were validated by UHPLC-MS/MS in different types of dry herbs, which can be used as food and/or medicinal purposes. Mancozeb was used in the validation of the EBDC method, where it was initially complexed with EDTA, derivatized, extracted with dimethyl sulfate in acetonitrile, magnesium sulfate (MgSO4), and sodium chloride (NaCl), and then purified using primary secondary amine (PSA). In the ETU method, L-cysteine hydrochloride monohydrate was added to the samples before extraction with acetonitrile, MgSO4, and NaCl, followed by purification with PSA. A pesticide-free blend of seven herbs (boldo, artichoke, "espinheira-santa", cat's claw, senna, chamomile, and cascara buckthorn) comprising distinct parts of the plants (leaves, bark, flowers and/or stems) was used as a control for method validation. Recoveries ranged from 79 to 113% for EBDC and 81 to 109% for ETU. Repeatability and intermediate precision were <20% for both methods. The limit of quantification was 0.03 mg kg-1 for EBDC (0.02 mg kg-1 of CS2) and ETU. The limit of detection (LOD) was set at 1/3 of the LOQ (0.01 mg kg-1 for both analytes). In total, 103 samples of 33 different dry herbs were analyzed, of which 19.4% were positive for EBDC (≥LOD), but no ETU residues were found in any of the analyzed samples. Given the absence of registered dithiocarbamates for use in the investigated herbs in Brazil, the positive results suggest potential illegal pesticide use or cross-contamination, especially considering the low concentrations detected in most samples. Although exposure to EBDC through the consumption of medicinal herbs from positive samples did not indicate a health risk to consumers, these plants must be monitored to prevent illicit pesticide usage, particularly when the herbs are intended for therapeutic purposes.

The mother-offspring transfer of chlorothalonil through human breast milk: A multi-city cross-sectional study.

4-Hydroxychlorothalonil (4-OH CHT), the main metabolite of chlorothalonil and the most widely used fungicide, has been frequently detected in human samples during monitoring. 4-OH CHT may exhibit higher toxicity and persistence in the environment compared to its prototype. In this study, a total of 540 paired serum and breast milk samples from pregnant women in three provinces in China were monitored for contaminant residues. 4-OH CHT was analyzed in the samples using ultra high-performance liquid chromatography - high-resolution mass spectrometry with a detection limit of 20 ng/L. The study investigated the effects of demographic factors, such as BMI, region of residence, and education level, on the levels of 4-OH CHT residues in serum and breast milk. Among the three provinces, the highest median concentration of 4-OH CHT in serum samples was observed in Hebei (1.04 × 103 ng/L), while the highest median concentration of 4-OH CHT in breast milk samples was observed in Hubei and Guangdong (491 ng/L). Multiple linear regression was used to investigate the significant positive correlation between 4-OH CHT in serum and breast milk (p = 0.000) after adjusting for personal characteristics. Based on this, the study further explored the influencing factors of transfer efficiencies (TEs) in conjunction with the individual TEs and the personal characteristics of the participants. Our results demonstrated that the age of the volunteers and their exercise habits had an effect on TEs, but further studies are needed to determine whether exercise leads to an increase in TEs.

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.

Simultaneous determination of four fungicide residues in figs using liquid chromatography tandem mass spectrometry.

Dissipative behavior and final residue levels of difenoconazole, prochloraz, propiconazole, and pyraclostrobin in figs were investigated using field trials and laboratory assays. A three-factor, three-level orthogonal test was designed to optimize the pretreatment conditions of the method. A method was established using high-performance liquid chromatography tandem mass spectrometry for the determination of difenoconazole, prochloraz, propiconazole, and pyraclostrobin residues in figs. The limit of quantification for all four targets in figs was 0.002 mg/kg. Difenoconazole, prochloraz, propiconazole, and pyraclostrobin are readily digestible pesticides in figs with half-lives of 6.4, 6.2, 4.8, and 7.9 days, respectively. Residues of difenoconazole, prochloraz, propiconazole, and pyraclostrobin in figs were below the European Union established residue levels of 0.1, 0.03, 0.01, and 0.02 mg/kg, respectively, at day 7 after application. Pyraclostrobin, propiconazole, difenoconazole, and prochloraz were applied twice at doses of 75, 125, 150, and 200 mg a.i./kg at 7-day intervals, and the residues of the four fungicides in figs were acceptable 7 days after the last application. Therefore, the safety interval can be set at 7 days for 70% difenoconazole-prochloraz wettable powder and 40% pyraclostrobin-propiconazole aqueous emulsion according to the protocol.

Fluorescent and Colorimetric Dual-Readout Immunochromatographic Assay for the Detection of Phenamacril Residues in Agricultural Products.

The fungicide phenamacril has been employed to manage Fusarium and mycotoxins in crops, leading to persistent residues in the environment and plants. Detecting phenamacril is pivotal for ensuring environmental and food safety. In this study, haptens and artificial antigens were synthesized to produce antiphenamacril monoclonal antibodies (mAbs). Additionally, gold nanoparticles coated with a polydopamine shell were synthesized and conjugated with mAbs, inducing fluorescence quenching in quantum dots. Moreover, a dual-readout immunochromatographic assay that combines the positive signal from fluorescence with the negative signal from colorimetry was developed to enable sensitive and precise detection of phenamacril within 10 min, achieving detection limits of 5 ng/mL. The method's reliability was affirmed by using spiked wheat flour samples, achieving a limit of quantitation of 0.05 mg/kg. This analytical platform demonstrates high sensitivity, outstanding accuracy, and robust tolerance to matrix effects, making it suitable for the rapid, onsite, quantitative screening of phenamacril residues.

Rapid and specific detection of thiabendazole: enzymatic digestion-enabled fluorescent aptasensor.

Thiabendazole, a widely used broad-spectrum fungicide in agriculture, poses risks to human health. To monitor its presence in water, we propose a fluorescent aptasensor utilizing Escherichia coli exonuclease I (Exo I). The findings demonstrate a linear correlation between thiabendazole concentrations and digestion percentage, with a detection limit (LOD) exceeding 1 µM and a determination coefficient (R2) of 0.959. This aptamer-based fluorescence spectroscopy detection system holds promise for a rapid, specific, and sensitive analysis of thiabendazole in environmental waters and food matrices.

Determination of chlorothalonil in vegetables/fruits using liquid chromatography-tandem mass spectrometry with a discharge adapter interface.

RATIONALE: Chlorothalonil (CHT), a broad-spectrum fungicide, has been employed widely to control foliar diseases, whereas with a major metabolite of polar 4-hydroxychlorothalonil (CHT-4-OH), only an acceptable nonpolar CHT residue is allowed by most countries. This study involves the method development for CHT residue in vegetables/fruits using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with a novel modified discharge-adaptor (DA) interface. METHODS: CHT residue was analyzed using LC-MS/MS with DA interface (LC-DA-MS/MS), developed in our previous works. A DA was placed on the electrospray tip to switch the ionization modes. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied to extract CHT residue of vegetables/fruits efficiently with less sample preparation time and analysis cost. RESULTS: CHT and CHT-4-OH spiked in four different vegetables/fruits were extracted using the modified QuEChERS method. After LC with isocratic elution, CHT and CHT-4-OH were separated within 3 min. Using LC-DA-MS/MS, the ion signals of CHT were improved two to three times, and the limit of quantification of 5 ng/g and linearity (r2 > 0.99) in the range of 5-200 ng/g were achieved using 10 g of vegetables/fruits. The precision and accuracy were within 15% each. The modified QuEChERS and LC-DA-MS/MS were applied to examine eight field-grown vegetables/fruits; 9.5 and 2588.9 ng/g of CHT were detected in two vegetables/fruits. CONCLUSION: LC-DA-MS/MS combined with modified QuEChERS was successfully applied to determine CHT residue <10 ng/g in vegetables/fruits and with satisfied validation results. The developed method could reduce both analysis cost and time, attributing to simplifications in modified QuEChERS, isocratic elution, and DA interface in LC-DA-MS/MS.

Compound-Specific Isotope Analysis Provides Direct Evidence for Identifying the Source of Residual Pesticides Diazinon and Procymidone in the Soil-Plant System.

Compound-specific isotope analysis stands as a promising tool for unveiling the behavior of pesticides in agricultural environments. Using the commercial formulations of persistent fungicide procymidone (PRO) and less persistent insecticide diazinon (DIA), respectively, we analyzed the concentration and carbon isotope composition (δ13C) of the residual pesticides through soil incubation experiments in a greenhouse (for 150 days) and lab conditions (for 50-70 days). Our results showed that the magnitude of δ13C variation depends on pesticide specificity, in which PRO in the soil exhibited little variation in δ13C values over the entire incubation times, while DIA demonstrated an increased δ13C value, with the extent of δ13C variability affected by different spiking concentrations, plant presence, and light conditions. Moreover, the pesticides extracted from soils were isotopically overlapped with those from crop lettuce. Ultimately, the isotope composition of pesticides could infer the degradation and translocation processes and might contribute to identifying the source(s) of pesticide formulation in agricultural fields.

Rapid detection of tebuconazole based on hydrogel SERS chips.

Tebuconazole is one of the most commonly used fungicides in agricultural production, that has the merits of highly effectiveness, broad spectrum and systemic function. Excessive tebuconazole may pose a great threat to human and animal health. Traditional detection techniques for tebuconazole usually have limitations such as expensive equipment, poor antibody stability, and time-consuming procedures. Herein, a sensitive sensor is developed for the rapid detection of tebuconazole based on hydrogel surface-enhanced Raman scattering (SERS) chips. Aggregated Ag nanoparticles (a-AgNPs) with tunable localized surface plasmon resonance (LSPR) wavelength are in-situ synthesized in polyvinyl alcohol (PVA) solution for preparing hydrogel SERS chips. Three hydrogel SERS chips are obtained to match the three commonly used laser wavelengths. On the basis, a match laser wavelength is selected according to the energy levels of tebuconazole and the Fermi level of a-AgNPs to gain a strong chemical enhancement. At the same time, the chip with a corresponding LSPR wavelength to the laser is applied to obtain a strong electromagnetic enhancement. Thus, highly sensitive SERS signal of tebuconazole is obtained. Furthermore, the obtained hydrogel SERS chips have good repeatability, outstanding reproducibility and strong anti-interference ability, and show outstanding reliability in practical applications. As a result, the SERS chips offer a reliable and convenient platform for the quick detection of tebuconazole in foods. The detection limit is as low as 1 ppb, and the recoveries is distributed in the range of 94.66-106.70 %. This work would promote greatly the application of SERS in small molecule detection.

Efficient and practical in-jar silicone rubber based passive sampling for simultaneous monitoring of emerging fungicides in water and soils.

The occurrence and ecological impacts of emerging fungicides in the environment has gained increasing attention. This study applied an in-jar passive sampling device based on silicone rubber (SR) film to measuring the freely dissolved concentration (Cfree) of 6 current-use fungicides as a critical index of bioavailability in water and soils. The kinetics parameters including SR-water, soil-water, and organic carbon-water partition coefficients and sampling rates of the target fungicides were first attained and characterized well with their physicochemical properties. The in situ and ex situ field deployment in Hefei City provided the assessment of contaminated levels for these fungicides in rivers and soils. The Cfree of triadimefon and azoxystrobin was estimated at 0.54 ± 0.07-17.4 ± 2.5 ng L-1 in Nanfei River and Chao Lake, while triadimefon was only found in Dongpu Reservoir water with Cfree below 0.66 ± 0.04 ng L-1. The results exhibited that the equilibrium duration of 7 d was suitable for water application but a longer interval of 14 d was recommended for soil sampling. This work demonstrated the advantages of the proposed strategy in terms of fast monitoring within 2 weeks and high sensitivity down to detection limits in 0.5-5 ng L-1. The in-jar passive sampling device can be extrapolated to the evaluation for a wide coverage of organic pollutants in water and soils.

Tracing the dissipation of difenoconazole, its metabolites and co-formulants in tomato: A comprehensive analysis by chromatography coupled to high resolution mass spectrometry in laboratory and greenhouse trials.

The study evaluated Ceremonia 25 EC®, a plant protection product (PPP) containing difenoconazole, in tomato crops, to identify potential risks associated with PPPs, and in addition to this compound, known metabolites from difenoconazole degradation and co-formulants present in the PPP were monitored. An ultra high performance liquid chromatography coupled to quadrupole-Orbitrap mass analyser (UHPLC-Q-Orbitrap-MS) method was validated with a working range of 2 µg/kg (limit of quantification, LOQ) to 200 µg/kg. Difenoconazole degradation followed a biphasic double first-order in parallel (DFOP) kinetic model in laboratory and greenhouse trials, with high accuracy (R2 > 0.9965). CGA-205374, difenoconazole-alcohol, and hydroxy-difenoconazole metabolites were tentatively identified and semi-quantified in laboratory trials by UHPLC-Q-Orbitrap-MS from day 2 to day 30. No metabolites were found in greenhouse trials. Additionally, 13 volatile co-formulants were tentatively identified by gas chromatography (GC) coupled to Q-Orbitrap-MS, detectable up to the 7th day after PPP application. This study provides a comprehensive understanding of difenoconazole dissipation in tomatoes, identification of metabolites, and detection of co-formulants associated with the applied PPP.

Residues determination, risk assessment, and dissipation behavior of myclobutanil formulation on apple.

This study aimed to investigate the dissipation pattern, risk assessment, and waiting period of myclobutanil on apple fruit (Malus domestica Borkh.) under temperate conditions in Kashmir, India. The study involved the application of myclobutanil 10 WP at a single recommended dosage (125 g a.i. ha-1) and double dosage (250 g a.i. ha-1) on Red Velox apple trees, 2 months before harvest. GC equipped with an electron capture detector was used to analyze myclobutanil residues in fruit samples. The study revealed that myclobutanil, at both recommended and double recommended doses, dissipated rapidly and became nondetectable after 55 and 60 days, respectively. The waiting period for myclobutanil application was determined to be 12.41 days for the single dose and 25.58 days for the double dose, respectively. These waiting periods were based on the maximum residue limit of 0.6 ppm as prescribed by the Codex Alimentarius Commission, Food Safety and Standards Authority of India, and European Commission. The study concludes that myclobutanil 10 WP is safe for consumers at both recommended and double recommended doses when applied 2 months before harvest. Risk assessment, considering the average daily apple consumption in India and theoretical maximum residue contributions (TMRCs), indicates negligible health hazards even at double the recommended dosage. The calculated TMRC values at Day 0 were significantly below the maximum permissible intake. For average and maximum myclobutanil residues at single and double doses, the TMRC values were found to be 0.0069 and 0.0070 mg day-1 person-1 and 0.0105 and 0.0106 mg day-1 person-1, respectively. These results indicate that myclobutanil, when used according to recommended dosages and waiting periods, poses minimal health risks to consumers. The study emphasizes the importance of prudent fungicide use to minimize fungicide residues on fruits, thereby ensuring their safety for consumption.

Quantitative MALDI-MS and Imaging of Fungicide Pyrimethanil in Strawberries with 2-Nitrophloroglucinol as an Effective Matrix.

This work explores the use of 2-nitrophloroglucinol (2-NPG) as a matrix for quantitative analysis of the fungicide Pyrimethanil (PYM) in strawberries using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and imaging. 2-NPG was selected for PYM analysis for optimum sensitivity and precision compared to common matrices α-cyano-4-hydroxylcinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB). PYM-sprayed strawberries were frozen 0, 1, 3, and 4 days after treatment and sectioned for MALDI imaging. The remaining part of each strawberry was processed using quick easy cheap effective rugged and safe (QuEChERS) extraction and analyzed by MALDI-MS and ultraperformance liquid chromatography multireaction-monitoring (UPLC-MRM). MALDI-MS showed comparable performance to UPLC-MRM in calibration, LOD/LOQ, matrix effect, and recovery, with the benefit of fast analysis. The MALDI imaging results demonstrated that PYM progressively penetrated the interior of the strawberry over time and the PYM concentration on tissue measured by MALDI imaging correlated linearly with MALDI-MS and UPLC-MRM measurements and accounts for 79% MALDI-MS and 85% UPLC-MRM values on average. Additionally, quartz crystal microbalance (QCM) was introduced as a new approach to determine strawberry tissue mass per area for MALDI imaging absolute quantitation with sensitive, direct, and localized measurements. This work demonstrates the first example of absolute quantitative MALDI imaging of pesticides in a heterogeneous plant tissue. The novel use of the 2-NPG matrix in quantitative MALDI-MS and imaging could be applied to other analytes, and the new QCM tissue mass per area method is potentially useful for quantitative MALDI imaging of heterogeneous tissues in general.

Novel litchi-like Au-Ag nanospheres driven dual-readout lateral flow immunoassay for sensitive detection of pyrimethanil.

Pyrimethanil (PYR) is a fungicide that is harmful to consumers when present in foods at concentrations greater than maximum permitted residue levels. High-performance immunoprobes and dual-readout strategy may be useful for constructing sensitive lateral flow immunoassay (LFIA). Herein, the prepared litchi-like Au-Ag bimetallic nanospheres (LBNPs) exhibited high mass extinction coefficients and fluorescence quenching constants. Benefiting from LBNPs and dual-readout mode, the limits of detection of LBNPs-CM-LFIA and LBNPs-FQ-LFIA for PYR were 0.957 and 0.713 ng mL-1, which were 2.54- and 3.41-fold lower than that of gold nanoparticles-based LFIA, respectively. The limits of quantitation of LBNPs-CM-LFIA and LBNPs-FQ-LFIA were 3.740 and 1.672 ng mL-1, respectively. LBNPs-LFIA was applied to detect PYR in cucumber and grape samples with satisfactory recovery (90%-111%). LBNPs-LFIA showed good agreement with LC-MS/MS for the detection of PYR in the samples. Accordingly, this sensitive and accurate dual-readout LFIA based on LBNPs can be effectively applied for food safety.