Development and inter-laboratory validation of analytical methods for glufosinate and its two metabolites in foods of plant origin.

Glufosinate is widely used to control various weeds. Glufosinate and its main metabolites have become the focus of attention because of their high water solubility and persistence in aquatic systems. Quantification of the agrochemical product and its metabolite residues is essential for the safety of agricultural products. In this study, a highly specific, simple method was developed to directly determine glufosinate and its metabolite residues in 21 plant origin foods by liquid chromatography with tandem mass spectrometry (LC-MS/MS), and it was validated on 11 foods in five laboratories. Finally, the repeatability limit, reproducibility limit, and uncertainty of the method were calculated based on these validated data and used to support the more accurate detection results. Four different chromatographic columns were used to analyze three target compounds, and the anionic polar pesticide column showed the optimum separation and peak shape. Composition of the mobile phase, extraction solvent, and the clean-up procedure were optimized. The developed method was validated on 21 plant origin foods. The average recoveries were 74-115% for all matrices. The validation results of five laboratories showed this method had a good repeatability (RSDr < 9.5%) and reproducibility (RSDR < 18.9%). The method validation parameters met the requirements of guidance established by the European Union (EU) and China for pesticide residue analysis. This methodology can be used for a routine monitoring that performs well for glufosinate and its metabolite residues.

The combination of chemical fertilizer affected the control efficacy against root-knot nematode and environmental behavior of abamectin in soil.

Chemical fertilizer and pesticide are necessary in agriculture, which have been frequently used, sometimes even at the same time or in combination. To understand the interactions of them could be of significance for better use of these agrochemicals. In this study, the influence of chemical fertilizers (urea, potassium sulfate, ammonium sulfate and superphosphate) on the control efficacy and environmental behavior of abamectin was investigated, which could be applied in soil for controlling nematodes. In laboratory assays, ammonium sulfate at 1 and 2 g/L decreased the LC50 values of abamectin to Meloidogyne incognita from 0.17 mg/L to 0.081 and 0.043 mg/L, indicating it could increase the contact toxicity. In greenhouse trial, ammonium sulfate at 1000 mg/kg increased the control efficacy of abamectin by 1.37 times. Meanwhile, the combination of abamectin with ammonium sulfate could also promote the tomato seedling growth as well as the defense-related enzyme activity under M. incognita stress. The persistence and mobility of abamectin in soil were significantly elevated by ammonium sulfate, which could prolong and promote the control efficacy against nematodes. These results could provide reference for reasonable use of abamectin and fertilizers so as to increase the control efficacy and minimize the environmental risks.

Nano-selenium repaired the damage caused by fungicides on strawberry flavor quality and antioxidant capacity by regulating ABA biosynthesis and ripening-related transcription factors.

Recently, studies have shown that pesticides may have adverse effects on the flavor quality of the fruits, but there is still a lack of appropriate methods to repair the damage. This study investigated the effects and mechanism of applying the emerging material, nano­selenium, and two fungicides (Boscalid and Pydiflumetofen) alone or together on the flavor quality and antioxidant capacity of strawberries. The results showed that the two fungicides had a negative impact on strawberry color, flavor, antioxidant capacity and different enzymatic systems. The color damage was mainly attributed to the impact on anthocyanin content. Nano­selenium alleviated the quality losses by increasing sugar-acid ratio, volatiles, anthocyanin levels, enzyme activities and DPPH scavenging ability and reducing ROS levels. Results also showed that these damage and repair processes were related to the regulation of flavor and ripening related transcription factors (including FaRIF, FaSnRK1, FaMYB10, FaMYB1, FaSnRK2.6 and FaABI1), the upregulation of genes on sugar-acid, volatile, and anthocyanin synthesis pathways, as well as the increase of sucrose and ABA signaling molecules. In addition, the application of nano-Se supplemented the selenium content in fruits, and was harmless to human health. This information is crucial for revealing the mechanisms of flavor damage caused by pesticides to strawberry and the repaired of nano­selenium, and broadens the researching and applying of nano­selenium in repairing the damage caused by pesticides.

Research progress of applications for nano-materials in improved QuEChERS method.

The quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is widely used in sample pretreatment in agricultural products, food, environment, etc. And nano-materials are widely used in QuEChERS method due to its small size and large specific surface area. In this review, we examine the typical applications of several commonly used nano-materials in improved QuEChERS method. These materials include multi-walled carbon nanotubes (MWCNTs) and their derivatives, magnetic nanoparticles (MNPs), metal organic frameworks (MOFs), covalent organic frameworks (COFs), graphene oxide (GO), lipid and protein adsorbent (LPAS), cucurbituril (CBs), and carbon nano-cages (CNCs), and so on. The strengths and weaknesses of each nano-material are presented, as well as the challenging aspects that need to be addressed in future research. By comparing the applications and the current technology development, this review suggests utilizing artificial intelligence (AI) to screen suitable combinations of purification agents and performing virtual simulation experiments to verify the reliability of this methodology. By doing so, we aim to accelerate the development of new products and decrease the cost of innovation. It also recommends designing smarter pretreatment instruments to enhance the convenience and automation of the sample pretreatment process and reduce the margin for human error.

Nano-selenium enhances melon resistance to Podosphaera xanthii by enhancing the antioxidant capacity and promoting alterations in the polyamine, phenylpropanoid and hormone signaling pathways.

Powdery mildew is one of the main problematic diseases in melon production, requiring the use of chemical pesticides with disease-resistant cultivars for control. However, the often rapid acquisition of fungicidal resistance by mildew pathogens makes this practice unsustainable. The identification of crop treatments that can enhance resistance to powdery mildew resistance is therefore important to reduce melon crop attrition. This study indicates that the application of Nano-Se can reduce the powdery mildew disease index by 21-45%. The Nano-Se treatment reduced reactive oxygen species (ROS) and malondialdehyde (MDA) accumulation, with increases in glutathione (GSH), proline and 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH). Increases were also observed in the activities and transcriptional levels of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD). Assays with four different cultivars of melon with differing levels of mildew resistance demonstrated that relative to the control, the Nano-Se treatment resulted in larger responses to mildew infection, including increases in the levels of putrescine (PUT; 43-112%) and spermine (SPM; 36-118%), indoleacetic acid (IAA; 43-172%) and salicylic acid (SA; 24-73%), the activities of phenylalanine ammonium lyase (PAL), trans-cinnamate 4-hydroxylase (C4H) and 4-coumarate: Co A ligase (4CL) of the phenylpropanoid pathway (22-38%, 24-126% and 19-64%, respectively). Key genes in the polyamine and phenylpropanoid pathway were also upregulated. These results indicate that the foliar application of Nano-Se improved melon defenses against powdery mildew infection, with a significant reduction in mildew disease development.

Improving red pitaya fruit quality by nano-selenium biofortification to enhance phenylpropanoid and betalain biosynthesis.

Red pitaya, the representative tropical and subtropical fruit, is vulnerable to quality deterioration due to climate or agronomic measures. Nano-selenium (Nano-Se) has shown positive effects on crop biofortification in favour of reversing this situation. In this study, Se could be enriched efficiently in red pitayas via root and foliar application by Nano-Se, which induced higher phenolic acids (16.9-94.2%), total phenols (15.7%), total flavonoids (29.5%) and betacyanins (34.1%) accumulation in flesh. Richer antioxidative features including activities of SOD (25.2%), CAT (33.8%), POD (77.2%), and levels of AsA (25.7%) and DPPH (14.7%) were obtained in Nano-Se-treated pitayas as well as in their 4-8 days shelf-life. The non-targeted metabolomics indicated a boost in amino acids, resulting in the stimulation of phenylpropanoid and betalain biosynthesis. In conclusion, the mechanism of Nano-Se biofortification for red pitaya might be fortifying pigment, as well as the enzymatic and non-enzymatic antioxidant substances formation by regulating primary and secondary metabolism facilitated by Se accumulation.

Nano-selenium enhances sugarcane resistance to Xanthomonas albilineans infection and improvement of juice quality.

Selenium is an important trace element that is beneficial to human health and can enhance plant resistance and crop quality. The occurrence of up-to-date nanotechnology greatly promotes the beneficial efficiency of this trace element on crops. The discovery of nano-Se increased the crop quality and reduced plant disease in different plant. In this study, we reduced sugarcane leaf scald disease incidence by exogenously spraying different concentrations (5 mg/L and 10 mg/L) of nano-Se. Additional studies revealed that spraying of nano-Se reduced reactive oxygen species (ROS) and H2O2 accumulation, and increased antioxidant enzyme activities in sugarcane. The nano-selenium treatments also increased the content of jasmonic acid (JA) and the expression of JA pathway genes. Furthermore, we also found that use nano-Se treatment in an appropriate way can enhance the quality of cane juice. The brix of the cane juice of the selenium-enriched treatment was significantly higher than that of the control group, which was 10.98% and 20.81% higher than that of the CK group, respectively. Meanwhile, the content of certain beneficial amino acids was increased, with the highest being 3.9 times higher than the control. Taken together, our findings inferred that nano-Se could act as a potential eco-fungicide to protect sugarcane from can be used as a potential ecological bactericide to protect sugarcane from Xanthomonas albilineans infections, and improve sugarcane quality. The results arising from this study not only introduces an ecological method to control X. albilineans, but also provides a deep insight into this trace elements for improving juice quality.

Ionic Liquid-Dispersive Micro-Extraction and Detection by High Performance Liquid Chromatography-Mass Spectrometry for Antifouling Biocides in Water.

A simple analytical method was developed and evaluated for the determination of two antifouling biocides using an ionic liquid-dispersive liquid-liquid micro-extraction (IL-DLLME) and a high-performance liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) analysis. Irgarol 1051 and Sea-Nine 211 were extracted from deionized water, lake water, and seawater using IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIm][PF6]) and ethyl acetate as the extraction solvent and the dispersion solvent. Several factors were considered, including the type and volume of extraction and dispersive solvent, IL amount, sample pH, salt effect, and cooling temperature. The developed method resulted in a recovery range of 78.7-90.3%, with a relative standard deviation (RSD, n = 3) less than 7.5%. The analytes were enriched greater than 40-fold, and the limits of detection (LOD) for two antifouling biocides were 0.01-0.1 µg L-1. The method was effectively applied for the analysis of real samples of freshwater as well as samples of seawater.

Integrated non-targeted and targeted metabolomics analysis reveals the mechanism of inhibiting lignification and optimizing the quality of pea sprouts by combined application of nano-selenium and lentinans.

BACKGROUND: Lignification causes a detrimental impact on the quality of edible sprouts. However, the mechanism of inhibition of lignification of edible sprouts by nano-selenium and lentinans remains unclear. RESULTS: To reveal the mechanism of lignification regulation of sprouts by nano-selenium and lentinans, this study investigated the changes in antioxidant indicators, phytohormones, polyphenols, and metabolites in the lignin biosynthesis in pea sprouts following sprays of nano-selenium or/and lentinans twice. There was an overall increase in the aforementioned indices following treatment. In particular, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans was more effective than their individual applications in enhancing peroxidase, catalase, DPPH free-radical scavenging rate, luteolin, and sinapic acid, as well as inhibiting malondialdehyde generation and lignin accumulation. Combined with the results from correlation analysis, nano-selenium and lentinans may inhibit lignification by enhancing antioxidant systems, inducing phytohormone-mediated signaling, and enriching precursor metabolites (caffeyl alcohol, sinapyl alcohol, 4-coumaryl alcohol). In terms of the results of non-targeted metabolomics, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans mainly affected biosynthesis of plant secondary metabolites, biosynthesis of phenylpropanoids, phenylpropanoid biosynthesis, arginine and proline metabolism, and linoleic acid metabolism pathways, which supported and complemented results from targeted screenings. CONCLUSION: Overall, the combined sprays of nano-selenium and lentinans showed synergistic effects in delaying lignification and optimizing the quality of pea sprouts. This study provides a novel and practicable technology for delaying lignification in the cultivation of edible sprouts. © 2023 Society of Chemical Industry.

Determination of Multi-pesticides Residues in Jasmine Flower and Its Scented Tea.

For minor crops such as jasmine, the lack of pesticide registration and maximum residue limits are important issues that need to be solved in order to facilitate trading and ensure food safety. Meanwhile, reliable and quick analytical methods for multi-pesticide residues in these commodities are few, but required by various stakeholders. In this study, a method for detecting twenty-five most frequently used pesticides in jasmine flower and its scented tea by multi-plug filtration cleanup and ultra-high-performance liquid chromatography-tandem mass spectrometry was developed and validated. The cleanup process was optimized and compared with the dispersive solid phase extraction procedure. The method was validated, showing that except for methomyl, recoveries of twenty-five pesticides were 64%-108%, with relative standard deviations (n = 5) of 0.33%-10%. The method was successfully applied to detect pesticide residues in marketed samples. The results showed that some flower and tea samples contained a combination of different pesticide residues.

Combined Application of Tank-mix Adjuvants, Mist Sprayer and Nano-selenium Promoted Pesticide Reduction and Enhanced Strawberry Quality.

In this paper, several technologies suitable for strawberry crops, such as armyworm boards, tank-mix adjuvants, mist sprayers combined with pesticide reduction, and biostimulant nano-selenium, were comprehensively applied and evaluated. The combined use of 60% etoxazole and bifenazate, bucket mixing additives, nano-selenium, and mist sprayers achieved an 86% prevention effect on red spiders. The prevention effect of pesticides according to the recommended dosage was 91%. Similarly, the disease index of strawberry powdery mildew in the green control group (60% carbendazim, bucket mixing additives, nano-selenium, and mist sprayer) decreased from 33.16 to 11.11, with a decrease of 22.05. The disease index of the control group decreased from 29.69 to 8.06, with a decrease of 21.63. Additionally, the combination of pesticide reduction and nano-selenium significantly improved the antioxidant activity and soluble sugar level of strawberry fruit and reduced water loss during storage. Therefore, the integrated application of green control technologies is beneficial for reducing the amount of chemical pesticides and improving their effectiveness, while enhancing the quality of strawberry fruits in disease and pest control.

Metabolomic analysis on the mechanism of nanoselenium alleviating cadmium stress and improving the pepper nutritional value.

Selenium (Se) maintains soil-plant homeostasis in the rhizosphere and regulates signaling molecules to mitigate cadmium (Cd) toxicity. However, there has been no systematic investigation of the effects of nano-selenium (nano-Se) on the regulation of non-target metabolites and nutritional components in pepper plants under Cd stress. This study investigated the effects of Cd-contaminated soil stress and nano-Se (1, 5, and 20 mg/L) on the metabolic mechanism, fruit nutritional quality, and volatile organic compounds (VOCs) composition of pepper plants. The screening of differential metabolites in roots and fruit showed that most were involved in amino acid metabolism and capsaicin production. Amino acids in roots (Pro, Trp, Arg, and Gln) and fruits (Phe, Glu, Pro, Arg, Trp, and Gln) were dramatically elevated by nano-Se biofortification. The expression of genes of the phenylpropane-branched fatty acid pathway (BCAT, Fat, AT3, HCT, and Kas) was induced by nano-Se (5 mg/L), increasing the levels of capsaicin (29.6%), nordihydrocapsaicin (44.2%), and dihydrocapsaicin (45.3%). VOCs (amyl alcohol, linalool oxide, E-2-heptaldehyde, 2-hexenal, ethyl crotonate, and 2-butanone) related to crop resistance and quality were markedly increased in correspondence with the nano-Se concentration. Therefore, nano-Se can improve the health of pepper plants by regulating the capsaicin metabolic pathway and modulating both amino acid and VOC contents.

Phenylboronic acid-functionalized cross-linked chitosan magnetic adsorbents for the magnetic solid-phase extraction of benzoylurea pesticides.

In this study, a 4-formylphenylboronic acid-modified cross-linked chitosan magnetic nanoparticle (FPBA@CCHS@Fe3 O4 ) was fabricated. The synthesized material was utilized as the magnetic solid-phase extraction adsorbent for the enrichment of six benzoylurea pesticides. In addition to B-N coordination, FPBA@CCHS@Fe3 O4 interacts with benzoylureas through hydrogen bonds and π-π stacking interaction on account of rich active groups (amino and hydroxyl) and aromatic rings in structure. Compared to traditional extraction methods, less adsorbent (20 mg) and reduced extraction time (3 min) were achieved. The adsorbent also exhibited good reusability (no less than 10 times). Coupled with a high-performance liquid chromatography-diode array detector, satisfactory recoveries (89.1-103.9%) and an acceptable limit of detection (0.2-0.7 µg/L) were obtained. Under optimized conditions, the established method was successfully applied to the tea infusion samples from six major tea categories with acceptable recoveries ranging from 76.8 to 110%, indicating its application potential for the quantitative detection of pesticides in complex matrices.

Nano-selenium enhances the antioxidant capacity, organic acids and cucurbitacin B in melon (Cucumis melo L.) plants.

Pesticides are widely used in melon production causing safety issues around the consumption of melon and increasing pathogen and insect tolerance to pesticides. This study investigated whether a nano-selenium (Nano-Se) spray treatment can improve resistance to biological stress in melon plants, reducing the need for pesticides, and how this mechanism is activated. To achieve this, we examine the ultrastructure and physio-biochemical responses of two melon cultivars after foliar spraying with Nano-Se. Nano-Se treatment reduced plastoglobulins in leaf mesophyll cells, thylakoid films were left intact, and compound starch granules increased. Nano-Se treatment also increased root mitochondria and left nucleoli intact. Nano-Se treatment enhanced ascorbate peroxidase, peroxidase, phenylalanine ammonia lyase, ß-1,3-glucanase, chitinase activities and their mRNA levels in treated melon plants compared to control plants (without Nano-Se treatments). Exogenous application of Nano-Se improved fructose, glucose, galactitol, stachyose, lactic acid, tartaric acid, fumaric acid, malic acid and succinic acid in treated plants compared to control plants. In addition, Nano-Se treatment enhanced cucurbitacin B and up-regulated eight cucurbitacin B synthesis-related genes. We conclude that Nano-Se treatment of melon plants triggered antioxidant capacity, photosynthesis, organic acids, and up-regulated cucurbitacin B synthesis-related genes, which plays a comprehensive role in stress resistance in melon plants.

Method Development and Validation of Seven Pyrethroid Insecticides in Tea and Vegetable by Modified QuEChERS and HPLC-MS/MS.

This study developed a quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure for determining seven pyrethroid pesticide residues in tea, cucumber, and tomato via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The overall average recoveries of the seven pyrethroids were 72%-104% (relative standard deviation (RSD); 2.0%-16.1%, 89%-109% (RSD; 0.7%-17.3%), 82%-110% (RSD; 1.6%-17.1%) for tea, cucumber and tomato, respectively. The determination coefficient (R2), the limit of detection (LOD), and the limit of quantification (LOQ) were ≥ 0.99, 0.007-1.875 µg kg-1, and 0.025-6.250 µg kg-1, respectively. The method was successfully used to monitor the pyrethroid pesticide residues in market samples. HPLC-MS/MS rapidly, sensitively, and accurately determined the pyrethroid pesticide residues.

Nanoselenium transformation and inhibition of cadmium accumulation by regulating the lignin biosynthetic pathway and plant hormone signal transduction in pepper plants.

Selenium (Se) can promote the growth and resistance of agricultural crops as fertilizers, while the role of nano-selenium (nano-Se) against Cd remains unclear in pepper plants (Capsicum annuum L.). Biofortification with nano-Se observably restored Cd stress by decreasing the level of Cd in plant tissues and boosting the accumulation in biomass. The Se compounds transformed by nano-Se were primarily in the form of SeMet and MeSeCys in pepper tissues. Differential metabolites and the genes of plant signal transduction and lignin biosynthesis were measured by employing transcriptomics and determining target metabolites. The number of lignin-related genes (PAL, CAD, 4CL, and COMT) and contents of metabolites (sinapyl alcohol, phenylalanine, p-coumaryl alcohol, caffeyl alcohol, and coniferaldehyde) were remarkably enhanced by treatment with Cd1Se0.2, thus, maintaining the integrity of cell walls in the roots. It also enhanced signal transduction by plant hormones and responsive resistance by inducing the biosynthesis of genes (BZR1, LOX3, and NCDE1) and metabolites (brassinolide, abscisic acid, and jasmonic acid) in the roots and leaves. In general, this study can enable a better understanding of the protective mechanism of nano-Se in improving the capacity of plants to resist environmental stress.

Exogenous salicylic acid alleviates the accumulation of pesticides and mitigates pesticide-induced oxidative stress in cucumber plants (Cucumis sativus L.).

Salicylic acid (SA) is an important signal molecule, regulating oxidative stress response in plants. In this study, we evaluated the influences of SA (1 mg L-1, 10 mg L-1 and 50 mg L-1) on the accumulation of clothianidin (CLO), dinotefuran (DFN) and difenoconazole (DFZ) (5 mg L-1) and pesticide-induced (CLO-10 mg L-1, DFN-20 mg L-1, and DFZ-10 mg L-1) oxidative stress in cucumber plants. Exogenous SA at 10 mg L-1 significantly reduced the half-lives of three pesticides in nutrient solution and prevented the accumulation of pesticides in roots and leaves. And the role of SA in reducing residues was related to the major accumulation sites of pesticides. By calculating the root concentration factor (RCF) and translocation factor (TF), we found that SA at 10 mg L-1 reduced the ability of roots to absorb pesticides and enhanced the translocation ability from roots to leaves. Roots exposed to high concentrations of three pesticides could reduce biomass, low chlorophyll content, increase the accumulation of reactive oxygen species (ROS) and proline, promote lipid peroxidation, and alter the activities of a range of antioxidant enzymes, respectively. Exogenous SA at low concentrations (1 mg L-1 and 10 mg L-1) significantly mitigated these negative effects. Hence, application of exogenous SA at 10 mg L-1 could effectively alleviate the accumulation of pesticides and induce stress tolerance in cucumber planting systems.

Simultaneous determination of 14 pesticide residues in tea by multi-plug filtration cleanup combined with LC-MS/MS.

A combined method of multi-plug filtration cleanup (m-PFC) and liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS) was established to simultaneously detect 14 pesticides in tea. The pesticides in water-soaked tea were extracted with acetonitrile. Cleanup of tea extract was performed using an m-PFC column packed with multiple cleanup materials: multi-walled carbon nano-tubes (MWCNTs), primary secondary amine (PSA) and anhydrous magnesium sulfate (MgSO4). The cleanup effect of the column was evaluated based on the rates of removal of tea components that interfered with pesticide recovery, henceforth referred to as interference components. Results showed that 14 pesticides had strong linearity in the range of 5-500 µg L-1 (r2 > 0.99). The quantitative limits were within the range of 3-50 µg kg-1. The average recoveries of 14 pesticides spiked into three different blank tea samples (green tea, black tea, oolong tea) at three levels of 0.05, 0.50 and 2.00 mg kg-1 were in the range of 62.3-108.8% with relative standard deviations of 0.2-13.6%. The m-PFC method can greatly improve the efficiency of sample pretreatment. Furthermore, this work provides methodological guidance on how to select cleanup materials and allocate their proportions.

Dual-layer column filtration cleanup and gas chromatography-tandem mass spectrometry detection for the analysis of 39 pesticide residues in porcine meat.

A rapid and effective method was developed for the analysis of 39 pesticide residues in porcine meat with dual-layer multiplug filtration cleanup and gas chromatography-tandem mass spectrometry detection. The cleanup process was performed with columns packed with two layers, namely multiwalled carbon nanotubes, C18 and anhydrous magnesium sulfate (MgSO4 ) as top layer, while mixture of florisil and MgSO4 as bottom layer. A single-layer method was tested in parallel, with columns packed with the same amount of absorbents. Extraction conditions and filtration cleanup process were optimized to obtain satisfied method performance. Method linearity was calculated with coefficients of determination more than 0.995. The limits of quantitation were verified with acceptable accuracy at the lowest spiked concentration of 0.01 mg/kg (except pyrimethanil). The recoveries at three fortified levels (0.01, 0.05, and 0.1 mg/kg) in five replicates were between 74 and 118% (except pyrimethanil) with relative standard deviations range from 1 to 16%. The matrix effects were in the range of 1.01 to 2.84. This new method was applied for the analysis of multipesticide residues in market samples of porcine meat. This study showed the dual-layer multiplug filtration cleanup demonstrated better performance than that with the single-layer columns in cleanup of porcine meat.

Dissipation of sixteen pesticide residues from various applications of commercial formulations on strawberry and their risk assessment under greenhouse conditions.

Twelve commercial pesticide formulations containing sixteen active ingredients were applied on greenhouse strawberries at recommended and double doses. The dynamics and dietary risk analysis were investigated. A modified QuEChERS method based on the use of multi-walled carbon nanotubes (MWCNTs) as adsorbent followed by LC-MS/MS and GC-MS/MS detection was utilized for sample analysis. The half-lives of studied pesticides were 4.6-12.6 days and 3.8-15.8 days from two application doses. Dietary levels from the residue concentrations of the individual pesticides at harvest was contrasted with the acceptable daily intake (ADI) and acute reference dose (ARfD). The dietary risk assessment adopt the risk quotient (RQ) for chronic risk and risk probability (RP) for long-term dietary intake risk, respectively. The dietary risk induced by the studied pesticide residues in strawberry was acceptable for consumers except the pesticide fumigants. The pesticide residues at different pre-harvest intervals (PHIs) under greenhouse conditions were compared with the established maximum residue limits (MRLs). To reduce the residue levels and potential safety risk, a longer PHI or reduced application rates should be conducted.