Dissipation behavior, residue distribution and risk assessment of three fungicides in pears.

BACKGROUND: Fungicides are often applied to pears before they are kept in storage facilities. The scientific application of pesticides can reduce unnecessary exposure, which in turn could benefit both humans and the environment. RESULTS: We investigated dissipation behavior and residue distribution, and conducted risk assessments for prochloraz, pyraclostrobin, and tebuconazole in pears stored under different conditions using ultra-performance liquid chromatography (UPLC). The recoveries of the three fungicides ranged from 76.5% to 114.5%, and the coefficients of variation were 1.0%-8.5%. The half-life (t1/2 ) ranges for degradation of the three fungicides in Dangshan Su pear peel were 8.8-13.9 days after storage at 25 °C and 99.0-346.6 days after storage at 2 °C. Among the three fungicides, tebuconazole had the lowest residue concentration in pear pulp (maximum of 0.226 mg·kg-1 ) and the longest half-life (≥ 231.0 days). Accordingly, among these fungicides, tebuconazole is the most suitable for the preservation of Dangshan Su pears during storage. Finally, we analyzed samples of six pear varieties from markets in China and found that the residue concentrations of the three fungicides in pear pulp and fruit met Chinese standards. CONCLUSION: The results provide a scientific basis for rationalizing the use of prochloraz, pyraclostrobin, and tebuconazole, and improving the safety of pears for eating. © 2019 Society of Chemical Industry.

Quantitative Determination of Acetamiprid in Pollen Based on a Sensitive Enzyme-Linked Immunosorbent Assay.

A sensitive biotinylated indirect competitive enzyme-linked immunosorbent assay (Bic-ELISA) was developed to detect acetamiprid pesticides in pollen, based on the heterogeneous coating antigen and biotinylated anti-acetamiprid monoclonal antibody. Under optimized experimental conditions, the detection limit for the Bic-ELISA was 0.17 ng/mL and the linear range was 0.25⁻25 ng/mL. The cross-reactivities could be regarded as negligible for the biotinylated antibodies with their analogues except for thiacloprid (1.66%). Analyte recoveries for extracts of spiked pollen (camellia pollen, lotus pollen, rape pollen) ranged from 81.1% to 108.0%, with intra-day relative standard deviations (RSDs) of 4.8% to 10.9%, and the average reproducibility was 85.4% to 110.9% with inter-assay and inter-assay RSDs of 6.1% to 11.7%. The results of Bic-ELISA methods for the Taobao's website samples were largely consistent with HPLC-MS/MS. Therefore, the established Bic-ELISA methods would be conducive to the monitoring of acetamiprid in pollen.

Dissipation and Migration of Pyrethroids in Auricularia polytricha Mont. from Cultivation to Postharvest Processing and Dietary Risk.

In order to ensure raw consumption safety the dissipation behavior, migration, postharvest processing, and dietary risk assessment of five pyrethroids in mushroom (Auricularia polytricha Mont.) cultivated under Chinese greenhouse-field conditions. Half-lives (t1/2) of pyrethroids in fruiting body and substrate samples were 3.10-5.26 and 17.46-40.06 d, respectively. Fenpropathrin dissipated rapidly in fruiting bodies (t1/2 3.10 d); bifenthrin had the longest t1/2. At harvest, pyrethroid residues in A. polytricha (except fenpropathrin) were above the respective maximum residue limits (MRLs). Some migration of lambda-cyhalothrin was observed in the substrate-fruit body system. In postharvest-processing, sun-drying and soaking reduced pyrethroid residues by 25-83%. We therefore recommend that consumers soak these mushrooms in 0.5% NaHCO3 at 50 °C for 90 min. Pyrethroids exhibit a particularly low PF value of 0.08-0.13%, resulting in a negligible exposure risk upon mushroom consumption. This study provides guidance for the safe application of pyrethroids to edible fungi, and for the establishment of MRLs in mushrooms to reduce pesticide exposure in humans.

Residue Dynamics and Risk Assessment of Prochloraz and Its Metabolite 2,4,6-Trichlorophenol in Apple.

The residue dynamics and risk assessment of prochloraz and its metabolite 2,4,6-trichlorophenol (2,4,6-TCP) in apple under different treatment concentrations were investigated using a GC-ECD method. The derivatization percent of prochloraz to 2,4,6-TCP was stable and complete. The recoveries of prochloraz and 2,4,6-TCP were 82.9%-114.4%, and the coefficients of variation (CV) were 0.7%-8.6% for the whole fruit, apple pulp, and apple peel samples. Under the application of 2 °C 2.0 g/L, 2 °C 1.0 g/L, 20 °C 2.0 g/L, and 20 °C 1.0 g/L treatment, the half-life for the degradation of prochloraz was 57.8-86.6 d in the whole fruit and apple peel, and the prochloraz concentration in the apple pulp increased gradually until a peak (0.72 mg·kg-1) was reached. The concentration of 2,4,6-TCP was below 0.1 mg·kg-1 in four treatment conditions and not detected (

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.

Residue Behavior of Chiral Fungicide Prothioconazole and Its Major Chiral Metabolite in Flour Product Processing.

This study systematically investigates the stereoselective metabolism and residue behavior of chiral pesticide prothioconazole enantiomers during the steaming, baking, and frying of steamed buns, bread, and deep-fried dough sticks. The results show that steaming, baking, and frying can significantly promote the degradation of the prothioconazole enantiomers. In low- and high-concentration treatments, the degradation rates of prothioconazole enantiomers were over 96.0% and 45.4%, respectively, and the residual concentration of prothioconazole-desthio enantiomers was less than 32.7 µg/kg (excluding fried processing). During the processing of steamed buns, bread, and deep-fried dough sticks, the enantiomer fraction (EF) value of the prothioconazole enantiomer was close to 0.5, and the stereoselectivity was not significant. During the processing of steamed buns (low concentration), bread (low and high concentrations), and deep-fried dough sticks (low concentration), the stereoselectivity of prothioconazole-desthio was significant, and preferential enantiomer degradation occurred. Following the analysis of 120 flour product samples, the residual risk.

Effect of formulation on the indoxacarb and lufenuron dissipation in maize and risk assessment.

The supervised field trials were conducted in maize crops using nano-microemulsion (NM) and a commercial formulation of indoxacarb and lufenuron to evaluate the effect of nano-formulation on the dissipation pattern. A modified QuEChERS (Quick Easy Cheap Effective Rugged and Safe)-UPLC-MS/MS (ultra-performance liquid chromatography tandem mass spectrometry) method was utilized for sample analysis. Results showed that the initial deposits of indoxacarb and lufenuron in plants using nano-microemulsion were 0.98 mg/kg and 8.18 mg/kg at recommended dosage, while using the commercial formulation, they were 0.85 mg/kg and 5.53 mg/kg, respectively. Moreover, half-life (t1/2) values of using nano-microemulsion were 1.25 days and 2.51 days, which were shorter than indoxacarb (1.87 days) and lufenuron (3.00 days) from the commercial formulation, suggesting that pesticide formulations have a moderate impact on the initial deposit and dissipation rate. The terminal residue test showed that indoxacarb and lufenuron residues in maize grain and maize straw were below the available maximum residue limit (MRL, 0.01 mg/kg), suggesting 2% indoxacarb NM and 5% lufenuron NM are safe to use under the recommended dosage. The risk quotient value (RQ of indoxacarb and lufenuron equal to 17.7% and 2.4%, respectively) also revealed an acceptable risk for human consumption. These findings provide scientific evidence of the proper application of 2% indoxacarb NM and 5% lufenuron NM on maize crops.

Toxic effects of detected pyrethroid pesticides on honeybee (Apis mellifera ligustica Spin and Apis cerana cerana Fabricius).

To obtain the presence of environmental contaminants in honeybee and compare the toxicity of the detected pesticides to Apis mellifera ligustica Spin and Apis cerana cerana Fabricius. In this work, 214 honeybee samples were collected to simultaneous monitoring 66 pesticides between 2016 and 2017 in China. A modified QuEChERS extraction method coupled with multi-residue analytical methods by Ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and Gas chromatography-mass spectrum (GC-MS). Among, four pyrethroid pesticides were selected to test and compare the acute oral toxicities of two honeybees. And the survival risk of beta-cypermethrin was analyzed to them. Using this method, 21 compounds were detected, including 3 neonicotinoids, 5 pyrethroids, 5 organophosphorus and 8 others. Importantly, detected frequencies of pyrethroid pesticides were accounted for 53.3%. Among, acute toxicity values (LD50) of four pyrethroid pesticides to the A.m. ligustica were higher than of that the A.c. cerana. When they were exposed to the same concentration of beta-cypermethrin (0.2906 mg/L), the survival rate of the A.m. ligustica (40.0%) was higher than the A.c. cerana (18.9%). Our work is valuable to analyze multiple pesticide residues of honeybees and evaluate the survival risk of two honeybee species, which also provides a basis for the risk assessment.

Acceptable risk of fenpropathrin and emamectin benzoate in the minor crop Mugua (Chaenomeles speciosa) after postharvest processing.

Production of minor crop varieties often requires intensive pesticide use, which raises serious concerns over food safety and human health. Chaenomeles speciosa (Sweet) Nakai as one of the representative of this kind of crops is therefore used for investigating the residue behavior of fenpropathrin and emamectin benzoate, a synthetic pyrethroid and macrocyclic lactone widely used as an insecticide, respectively, from cultivation to C. speciosa postharvest processing. Results showed that the degradation trends of those selected insecticides in C. speciosa followed first-order kinetics with an average half-life (t1/2) of 3.7-4.1 days and a dissipation rate of 97% over 14 days. The terminal residues of fenpropathrin and emamectin benzoate at 120 and 3 g a.i./ha were below the U.S Environmental Protection Agency (FAD, 1.00 mg/kg) and European Union (EU, 0.01 mg/kg) maximum residue limits (MRLs) in papaya species, respectively, when measured 14 days after the final application, which suggested that the use of these insecticides was safe for humans. Postharvest processing procedure resulted in a |90% reduction of the insecticides. Moreover, the hazard quotient (HQ) for C. speciosa decoction (with processing factors) indicated an acceptable risk for human consumption. These findings provide the scientific evidence of reasonable application and risk assessment of the selected pesticide residues in C. speciosa.

Analysis of exposure to pesticide residues from Traditional Chinese Medicine.

The safety of Traditional Chinese Medicine (TCM) is of concern worldwide. Herein, Paeoniae Radix Alba, Chaenomelis Fructus and Moutan Cortex, representing three medicinal components, were subjected to toxicological analysis to investigate possible pesticide contamination. Exposure using a point estimate model identified 47 residues that were simultaneously validated by the QuEChERS-UPLC-MS/MS method, which is sufficiently reliable for measuring residue concentrations. Of the 313 samples tested, 94.57% contained pesticide residues, with concentrations ranging from 0.10 to 1199.84 µg kg-1, of which >83.17% contained 4-15 different residues. Carbendazim was the most frequently detected pesticide (>85%), and procymidone, pendimethalin and phoxim were also abundant (median concentration = 15.33-623.12 µg kg-1). Risk assessment based on the hazard quotient/hazard index (HQ/HI) approach revealed that exposure to pesticide residues in all three TCMs (95th percentile) were far below levels that might pose a health risk. However, insecticides contributed to cumulative exposure, especially phoxim, and worryingly, several banned pesticides were detected. The results are of theoretical and practical value for evaluating the safety TCMs, and could improve their quality and safety.

Quantitative Ultra-Performance Liquid Chromatography Tandem Mass Spectrometry Method for Comparison of Prochloraz Residue on Garlic Sprouts after Soaking and Spraying Treatment.

Prochloraz is a fungicide that is widely used on vegetables to maintain freshness during storage. To ensure that prochloraz is used in a safe way that reduces the levels of residue on the product, we evaluated two treatment methods (soaking and spraying) that are commonly used for garlic sprouts. An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for prochloraz residue on garlic sprouts. The linear range of the method was 5⁻500 µg/kg and the correlation coefficient was 0.9983. The average recovery range was 88⁻94%, and the relative standard deviation range was 2.6⁻9.7%. Garlic sprout samples that had been soaked in or sprayed with prochloraz were collected from cold storage facilities in Laixi and Pingdu, China. For the soaked samples, the ranges for the levels of prochloraz residue on the whole garlic sprouts and stems (edible portion) were 15.76⁻25.14 mg/kg and 0.58⁻1.62 mg/kg, respectively. For the sprayed samples, the ranges for the levels of prochloraz residue on the whole garlic sprouts and stems were 1.85⁻7.89 mg/kg and 0.01⁻1.29 mg/kg, respectively. The results of this study provide a scientific basis for rationalizing the use of prochloraz and improving the safety of edible garlic sprouts.

Behavior of pesticides and their metabolites in traditional Chinese medicine Paeoniae Radix Alba during processing and associated health risk.

In Traditional Chinese Medicine (TCM), crude herbs are processed to obtain the medicinal parts of the plant, from which extracts are prepared for people to take as medicine. However, there is no report on the pesticide residual behavior in Chinese medicines during processing at present, and thus, a systematic study of the effects of different processing factors (PF) on pesticide removal in Chinese medicines and the associated risk of dietary exposure is urgently needed. This study main investigated the dissipation and metabolism of pesticides in Chinese medicine Paeoniae Radix Alba during processing, and the calculated pesticide PFs were also used to assess the risk of dietary exposure. For analyze samples, a simple and high-throughput multiresidue pesticide analysis method was developed and validated for pesticides and their metabolites in P. Radix. based on QuEChERS procedure combined with HPLC-MS/MS. Recoveries at three concentration levels were within 61.37%-117.82% with an associated precision RSD < 15% indicating satisfactory accuracy. TCM processing could be useful for the partial removal of several pesticide residues, with removal rate reaching 98%. The polarity is the dominant variable, which with a high contribution was the effectiveness of the treatment and the concentration factors for pesticides. The hazard quotients of all pesticides were much lower than the safety level, indicating low risk of dietary exposure. Results are of great theoretical and practical value for the scientific evaluation of the safety of Chinese medicines, improvement of the quality and safety level of Chinese medicine.

Degradation Dynamics and Dietary Risk Assessments of Two Neonicotinoid Insecticides during Lonicera japonica Planting, Drying, and Tea Brewing Processes.

The degradation dynamics and dietary risk assessments of thiamethoxam and thiacloprid during Lonicera japonica planting, drying, and tea brewing processes were systematically investigated using high-performance liquid chromatography. The half-lives of thiamethoxam and thiacloprid were 1.0-4.1 d in the honeysuckle flowers and leaves, with degradation rate constants k ranging from -0.169 to -0.696. The safety interval time was 7 d. The sun- and oven-drying (70 °C) percent digestions were 59.4-81.0% for the residues, which were higher than the shade- and oven-drying percentages at lower temperatures (30, 40, 50, and 60 °C, which ranged from 37.7% to 57.0%). The percent transfers of thiamethoxam and thiacloprid were 0-48.4% and 0-25.2%, respectively, for the different tea brewing conditions. On the basis of the results of this study, abiding by the safety interval time is important, and using reasonable drying methods and tea brewing conditions can reduce the transfer of thiamethoxam and thiacloprid to humans.

Migration and Accumulation of Octachlorodipropyl Ether in Soil-Tea Systems in Young and Old Tea Gardens.

The migration and accumulation of octachlorodipropyl ether (OCDPE) in soil-tea systems were investigated using a gas chromatography-electron capture detector (GC-ECD) method in young and old tea gardens. When the residual concentration of OCDPE was 100 g a.i. hm-2 in soils, the peak concentrations of OCDPE in fresh leaves of young and old tea plants were 0.365 mg/kg and 0.144 mg/kg, taking 45 days and 55 days, respectively. Equations for the accumulation curves of OCDPE in fresh leaves of young and old tea plants were Ct = 0.0227e0.0566t (R² = 0.9154) and Ct = 0.0298e-0.0306t (R² = 0.7156), and were Ct = 3.8435e0.055t (R² = 0.9698) and Ct = 1.5627e-0.048t (R² = 0.9634) for dissipation curves, with a half-life of 14.4 days and 12.6 days, respectively. These results have practical guiding significance for controlling tea food safety.

Factors Affecting Transfer of Pyrethroid Residues from Herbal Teas to Infusion and Influence of Physicochemical Properties of Pesticides.

The transfer of pesticide residues from herbal teas to their infusion is a subject of particular interest. In this study, a multi-residue analytical method for the determination of pyrethroids (fenpropathrin, beta-cypermethrin, lambda-cyhalothrin, and fenvalerate) in honeysuckle, chrysanthemum, wolfberry, and licorice and their infusion samples was validated. The transfer of pyrethroid residues from tea to infusion was investigated at different water temperatures, tea/water ratios, and infusion intervals/times. The results show that low amounts (0-6.70%) of pyrethroids were transferred under the different tea brewing conditions examined, indicating that the infusion process reduced the pyrethroid content in the extracted liquid by over 90%. Similar results were obtained for the different tea varieties, and pesticides with high water solubility and low octanol-water partition coefficients (log Kow) exhibited high transfer rates. Moreover, the estimated values of the exposure risk to the pyrethroids were in the range of 0.0022-0.33, indicating that the daily intake of the four pyrethroid residues from herbal tea can be regarded as safe. The present results can support the identification of suitable tea brewing conditions for significantly reducing the pesticide residue levels in the infusion.

An enzyme-linked chemiluminescent immunoassay developed for detection of Butocarboxim from agricultural products based on monoclonal antibody.

In this study, four different haptens around the oxime moiety of Butocarboxim were designed and synthesised. Two of the haptens were conjugated with bovine serum albumin (BSA) to serve as the immunogen and all the haptens were conjugated with ovalbumin (OVA) for the coating antigen. The anti-Butocarboxim monoclonal antibody (Mab) was selected based on eight immunogen/coating antigen combinations. The first enzyme-linked chemiluminescent immunoassay (ELCIA) for determining Butocarboxim in agricultural products was developed. Under the optimised conditions, the detection limit for the ELCIA was 20 ng·mL(-1) and the linear range was 27-2700 ng·mL(-1). Analyte recoveries for extracts of spiked agricultural (apple and greengrocery) products and tap water ranged from 97.18% to 107.00%. The developed immunoassay has great potential to be developed as a test kit offering a simple and cost-effective approach (such as lateral flow test strip) for screening purposes and evaluating environmental exposure to Butocarboxim.

A bare-eye based one-step signal amplified semiquantitative immunochromatographic assay for the detection of imidacloprid in Chinese cabbage samples.

A novel bare-eye based one-step signal amplified semi-quantitative immunochromatographic assay (SAS-ICA) was developed for detection of the pesticide imidacloprid. This method was based on competitive immunoreactions. Signal amplification was achieved by dual labeling of the test lines (TLs) on the strip using high affinity nanogold-biotinylated anti-imidacloprid mAb (BAb) and nanogold-streptavidin (Sa) probes. The relative color intensities of three TLs (TL-I, TL-II and TL-III) on a nitrocellulose (NC) membrane were used for direct visual analysis of the SAS-ICA strips, and could be used for semi-quantitation of analyte concentrations by observing what TLs disappeared in the amplification zone. Under optimized conditions, the following imidacloprid concentration ranges would be detected by visual examination of the SAS-ICA strip: 0-5ngmL(-1) (negative samples), and 5-25ngmL(-1), 25-250ngmL(-1), 250-1000ngmL(-1) and >1000ngmL(-1) (positive samples). The sensitivity (the visual detection limit (VDL) of TL-III) and semi-quantitative analytical capacity (when TL-III disappeared completely) of the SAS-ICA strip were 10-fold and 160-fold higher than those of traditional ICA, respectively. The developed SAS-ICA strip was applied to the analysis of spiked and authentic contaminated Chinese cabbage samples in the laboratory and under field conditions, and the results were validated by high-performance liquid chromatography (HPLC). This process could be adopted as a potential generous technique for all ICA-based detection methods.

Development of an enzyme linked immunosorbent assay and an immunochromatographic assay for detection of organophosphorus pesticides in different agricultural products.

OBJECTIVE: Organophosphorus (OP) pesticides are considered hazardous substances because of their high toxicity to nontarget species and their persistence in the environment and agricultural products. Therefore, it is important to develop a rapid, sensitive, and economical method for detecting OP pesticides and their residues in food and the environment. METHODS: A broad, selective monoclonal antibody (MAb) for organophosphorus pesticides was produced. Based on the MAb, an enzyme linked immunosorbent assay (ELISA) and an immunochromatography assay (ICA) for detecting OP pesticides in different agricultural products were developed using a binding inhibition format on microtiter plates and a membrane strip, respectively. RESULTS: Under the optimized conditions, the IC(50) values of the ELISA ranged from 3.7 to 162.2 ng mL(-1) for the 8 OP pesticides. The matrix interferences of Apple, Chinese cabbage, and greengrocery were removed by 40-fold dilution, the recoveries from spiked samples ranged from 79.1% to 118.1%. The IC(50) values of ICA for the 8 OP pesticides ranged from 11.8 to 470.4 ng mL(-1). The matrix interference was removed from the Chinese cabbage and Apple samples with 5-fold dilution, and the interference was removed from the greengrocery samples with 20-fold dilution. The recoveries from the spiked samples ranged between 70.6 and 131.9%. The established ELISA and ICA were specific selectivity for the 8 OP pesticides. CONCLUSIONS: The established ELISA is a sensitive screening method for the detection of OP pesticides, but the ELISA detection method depends on a laboratory platform and requires a relative long assay time and several steps operation. The established ICA is very useful as a screening method for the quantitative, semi-quantitative or qualitative detection of OP pesticides in agricultural products, and it has advantages over ELISA methods with regard to factors such as the testing procedure, testing time, and matrix interferences, among others.