A multi-residue method for the determination of 203 pesticides in rice paddies using gas chromatography/mass spectrometry

Assessment of residues from common pesticides and associated risks in Pakistan

Pesticide residues have become an escalating concern in Pakistan, raising significant risks to both public health and the environment. This review overviews the current status of pesticide contamination in the country, with a specific focus on residue levels in relation to Maximum Residue Limits (MRLs) and a comparative analysis with regional and global counterparts. Several studies reveal that 30% to 70% of tested food products, including fruits, vegetables, and animal-derived products, especially in Punjab and Sindh, exceed established MRLs. This level of contamination is considerably higher than in neighboring countries such as India, where MRL exceedance ranges from 20 to 30%, and Bangladesh, which reports lower levels due to stricter regulatory efforts. In comparison, developed countries, including those in the European Union and the United States, report less than 5% of food samples exceeding MRLs, often falling below 1% due to stringent safety standards. The high prevalence of pesticide residues in Pakistan poses severe health risks, including neurological disorders, reproductive problems, and cancer, particularly in vulnerable groups like children and pregnant women. Key factors contributing to these elevated pesticide levels include insufficient knowledge of safe pesticide use, the unregulated application of banned or expired products, improper safety protocols, and malfunctioning equipment. A prevailing reliance on pesticides as the sole pest control method further hinders the adoption of Integrated Pest Management (IPM) strategies. In conclusion, pesticide residue levels in Pakistan are above permissible MRLs compared to regional and global standards, underscoring the need for urgent improvements in pesticide regulation, enforcement, and the promotion of sustainable pest control methods like IPM to better protect human health and the environment.

Comparison of supercritical fluid chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry for the stereoselective analysis of chlorfenvinphos and dimethylvinphos in tobacco

This study used reversed-phase liquid chromatography-tandem mass spectrometry and supercritical fluid chromatography-tandem mass spectrometry for determination of the stereoisomers of chlorfenvinphos and dimethylvinphos in tobacco. Tobacco samples were extracted and purified with a modified quick, easy, cheap, effective, rugged, and safe technique using spherical carbon. The performance of both methodologies was comprehensively compared in terms of methods validation parameters (separation efficiency, linearity, selectivity, recovery, repeatability, sensitivity, matrix effect, etc.). Under optimized conditions, the calibration curves of the stereoisomers of chlorfenvinphos and dimethylvinphos in the range of 10-500 ng/mL showed excellent linearity with R2 ≥  0.997 in both methods. The adequate recoveries of analytes from three different spiked tobaccos were obtained using reversed-phase liquid chromatography-tandem mass spectrometry (86.1-95.7%) as well as supercritical fluid chromatography-tandem mass spectrometry (86.5-94.0%). The relative standard deviations for spiked samples were all below 7.0%. Compared with supercritical fluid chromatography-tandem mass spectrometry, lower matrix effects and LODs can be obtained in reversed-phase liquid chromatography-tandem mass spectrometry.

An all-embracing analytical method comprising modified QuEChERS-dispersive micro-solid-phase extraction-dispersive liquid-liquid microextraction using FeGA MOF for the extraction and preconcentration of pesticides simultaneously from juice and flesh of watermelon

For the first time, a comprehensive analytical method based on a one-dimensional metal-organic framework comprising "quick, easy, cheap, effective, rugged, and safe-dispersive micro solid phase extraction-dispersive liquid-liquid microextraction" was introduced in this research. Moreover, the first-ever attempt was accomplished to apply the iron-gallic acid metal-organic framework in analytical method development. The goal of the research was to analyze the pesticide content of watermelon comprehensively in its flesh and juice. Based on this, comprehensive and reliable food safety monitoring can be done. Initially, pesticides of the watermelon flesh were extracted using an mL volume of acetonitrile by vortexing. At the same time, the pesticides of watermelon juice were extracted from the juice matrix onto the sorbent particles facilitated by vortexing. The obtained acetonitrile phase was also used to desorb the analytes from the sorbent surface by vortexing. As a result, the pesticide content of both juice and flesh was extracted into the acetonitrile. The pesticide-enriched acetonitrile was then used as the disperser solvent by being merged with µL level of 1,2-dibromoethane and injection into deionized water. A cloudy solution was created as the result. Centrifugation triggered extractant at the bottom of the conical glass test tube and an aliquot of it was injected into a gas chromatograph equipped with a flame ionization detector. High enrichment factors (210-400), appreciable extraction recoveries (42-80%), wide linear ranges (3.20-1000 µg kg^-1), relative standard deviations in the ranges of 3.6-4.4% for intra- (n = 6) and 4.4-5.3% for inter-day (n = 3) precisions, and low limits of detection (0.43-0.97 µg kg^-1), and quantification (1.42-3.20 µg kg^-1) were obtained by the application of the developed method.

Fungicide-loaded mesoporous silica nanoparticles promote rice seedling growth by regulating amino acid metabolic pathways

Mesoporous silica nanoparticles (MSN) are widely researched as carriers for pesticides (including fungicides, insecticides and herbicides) to improve their effective utilization rate in the target plant. However, pesticides enter the target crops and may bring some impacts on the growth and physiological function of plants. When they are loaded to nanoparticles, different effects on the metabolic properties of target plants will be produced. In this study, thifluzamide-loaded MSN was prepared with average diameter of 80-120 nm. Rice seedlings were exposed for 7 days to different treatments of MSN, thifluzamide, and thifluzamide-loaded MSN. After treatment, non-targeted metabolomic method was employed to explore the metabolic pathways. It was found that the negative effect of thifluzamide to rice seedling was alleviated by thifluzamide-loaded MSN, since it increased amino acid metabolic pathways, which improved purine and pyrimidine metabolism and induced the production of total protein. Thifluzamide-loaded MSN can also relieve the damage of thifluzamide to rice seedlings by altering the chlorophyll, phenols and flavonoids content. In conclusion, it was proposed that the mechanism of fungicide-loaded MSN prevent plant from negative effects of fungicides by regulating the amino acid metabolic pathways.

Rapid detection of chlorpyrifos residue in rice using surface-enhanced Raman scattering coupled with chemometric algorithm

Due to the continuous development and progress of society and more and more attention to the quality and safety of food, rapid testing of pesticides in food is of great significance. In this paper, surface-enhanced Raman spectroscopy (SERS) and chemometric algorithms were employed collectively to quantify chlorpyrifos (CP) residues in rice samples. The SERS spectra from different concentrations (0.01-1000 μg/mL) of CP were collected using AgNPs-deposited-ZnO nanoflower (NFs)-like nanoparticles (Ag@ZnO NFs) SERS sensor. Four quantitative chemometric models for CP were comparatively studied, and the competitive adaptive reweighted sampling-partial least squares model achieved the best prediction and practical applicability for predicting CP levels with a limit of detection of 0.01 µg/mL. The results of the student's t-test showed no significant difference between this method and high-performance liquid chromatography (HPLC), and good relative standard deviation (RSD) indicated that this method could be used for the detection of CP in rice.

A Combination of Chromatography with Tandem Mass Spectrometry Systems (UPLC-MS/MS and GC-MS/MS), Modified QuEChERS Extraction and Mixed-Mode SPE Clean-Up Method for the Analysis of 656 Pesticide Residues in Rice

The emerging ungovernable application of pesticides in rice farming has attracted public concerns as these hazardous chemicals leave long-lasting environmental impacts and cause severe health effects. Here, an optimized analytical method was proposed for the measurement of 656 pesticide residues in rice samples collected in Vietnam. We utilized chromatography with tandem mass spectrometry systems (UPLC-MS/MS and GC-MS/MS) combined with a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method and adopted a mixed-mode SPE clean-up method for the analysis. The results showed that a total of 341 and 315 compounds were determined by UPLC- and GC-MS/MS, respectively. Usage of 10 mL MeCN, 5 mL H₂O and 1% glacial acetic acid as extraction solvent outperformed other mixtures in purifying the analytes from the sample matrix. Besides, pressure swing adsorption connected to a C18 cartridge with C18 placed on top exhibited remarkably more extracted compounds of high recovery which resulted in 299 and 318 compounds with recovery ranging from 70 to 120% in GC- and UPLC-MS/MS, respectively. Our optimized protocols also resulted in maximal limits of quantification of 10 μg Kg⁻¹ in both MS methods with repeatability and reproducibility less than 20%. Application of validated method on 20 rice samples collected in Hanoi, Vietnam showed that 14 samples were contaminated with at least one pesticide, and insecticide was the most detected group. Overall, the compliance of all method validation parameters to SANTE/12682/2019 Guideline demonstrates that this protocol can be employed for the effective management of Vietnam’s rice in accordance with international requirements.

Application of Hydrophobic Magnetic Nanoparticles as Cleanup Adsorbents for Pesticide Residue Analysis in Fruit, Vegetable, and Various Soil Samples

A cleanup procedure based on hydrophobic magnetic nanoparticles for QuEChERS extraction followed by GC-MS method for the simultaneous determination of 16 organochlorine pesticides was developed. The type and amount of cleanup adsorbents (C18/GCB/Fe₃O₄/Fe₃O₄@Triton), the volume and polarity of the extraction solvent were optimized. The method was validated according to SANTE/11813/2017 and ICH/2005/Q2/R1 guidelines. Spiked-sample recoveries of 84-108% with RSD below 8% were obtained for all the tested pesticides in strawberry. Quantification was carried out using matrix-matched calibration plots, which displayed good linearity (R² > 0.99), the limits of quantification being less than the maximum residue limits (MRL) for food. The elaborated procedure with satisfactory results was applied in to determine the pesticides in fruit, vegetable (strawberries, avocadoes, watermelons, radishes, and flesh kiwis) and soil (agricultural, urban and lab-made) samples. The most frequently founded pesticide residues were 4,4'-DDE, 4,4'-DDD, lindane, and 4,4'-DDT, which in all cases were found to be below MRL. The highest concentration of 4,4'-DDT was founded in agricultural and lab-made soils.

Automated inline pigment removal for the analysis of pesticide residues in spinach by liquid chromatography tandem mass spectrometry

An automated inline sample preparation (ILSP) method has been developed for pesticide residue analysis in spinach by LC-MS/MS. Chlorophyll pigments and other matrix constituents were removed from the sample extract using a UHPLC system equipped with an auxiliary pump, 6-port high pressure switching valve, and dual-directional ILSP cartridge containing bonded silica. The new procedure was evaluated as an entirely separate workflow using a simple solid-liquid extraction and as part of a cleanup strategy in conjunction with QuEChERS. Accuracy and precision experiments were conducted in spinach at two concentration levels (n = 6). Of the 63 pesticides tested, 86% (0.005 mg/kg) and 100% (0.05 mg/kg) displayed average recoveries within 70-120% and RSD values ≤20% for the ILSP method. In addition, low to moderate matrix effects (<50%) were calculated for 95% of the analytes. Overall performance of the proposed method was found to be better or comparable to a traditional QuEChERS procedure utilizing AOAC formulated salts and dSPE sorbents, while significantly reducing the amount of pigments reaching the MS source. The ILSP workflow is a simpler procedure with fewer steps that require less time than traditional extraction and cleanup techniques.

Upgrading analytical methodology through comparative study for screening of 267 pesticides/metabolites in five representative matrices using UPLC-MS/MS

A comparative study was conducted to replace the traditional screening method (MFDS#83) with the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) EN method for the determination of 267 pesticides/metabolites/plant activators/growth regulators in five representative crop matrices (mandarin, pepper, potato, rice, and soybean). In the traditional method, samples were extracted with acetonitrile and salt, and purified with a solid-phase extraction cartridge. In the QuEChERS method, the sample extraction was carried out using acetonitrile and a mixture of salts, and purification was performed using dispersive solid phase extraction. The limit of quantification (LOQ) for the MFDS#83 method was 0.0004 mg/kg, whereas for the QuEChERS EN method, the LOQ varied from 0.002 to 0.006 mg/kg for all analytes in various matrices. A six-point matrix-matched calibration curve was prepared for all analytes in five matrices for both methods. Both the MFDS#83 and QuEChERS EN methods provided excellent linearity, with the coefficients of determination (R²) ≥ 0.99 for most of the compounds. In both cases, the method was validated in terms of recovery and repeatability after the fortification of two different concentrations with three replicates for each of the concentrations. The QuEChERS EN method provided better recovery than the MFDS#83 method for all matrices except mandarin.

Modified QuEChERS Extraction and HPLC-MS/MS for Simultaneous Determination of 155 Pesticide Residues in Rice (Oryza sativa L.)

Rice (Oryza sativa L.) is the staple food of more than half of the world’s population. The main factors affecting the quality of rice include grain length, texture, stickiness, flavor, and aroma. Pesticides are intended for the protection of plant products from weeds, fungi, or insects. However, pesticides also result in negative effects such as environment disturbances, pest resistance and toxicity to both users and food consumers. The aim of this study was to conduct validation experiments of a method for the determination of multi-pesticides in rice, a model food of other cereals. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was used for the extraction of pesticide residues from rice followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with a triple quadrupole instrument using electrospray ionization. The analytical method has chromatography-tandem according to SANTE/11813/2017. The limit of quantification was 5 μg/kg. Recoveries for the 155 analyzed pesticides ranged between 77.1% for pirimiphos-ethyl and 111.5% for flutriafol and they were determined at 3 spiking levels. The proposed method was demonstrated to be quick, simple, precise, and accurate and allowed for evaluating the compliance of cereals samples with legislated maximum residue levels of pesticides in the European Union.

Metabolism of triflumuron in the human liver: Contribution of cytochrome P450 isoforms and esterases

Triflumuron (TFM) is a benzoylurea insecticide commonly used in Tunisian agriculture and around the world to control crop pests and flies as a promising alternative to conventional insecticides for its arthropod specificity and low toxicity. From the evidence available in animal models, it can be expected that the metabolism of TFM is catalyzed by cytochrome P450 (CYP) and esterases. However, no data are available on human metabolism of TFM with regards to phase I metabolism and CYP isoform specificity. Hence, this manuscript describes experimental investigations to underpin in vitro phase I TFM metabolism in human samples for the first time. TFM biotransformation by recombinant human CYPs was characterized, then human liver microsomes (HLM) and chemical specific inhibitors have been used to identify the relative contribution of CYPs and esterases. Our results showed that all CYP isoforms were able to metabolize TFM with different affinity and efficiency. The relative contribution based both on the kinetic parameters and the CYP hepatic content was 3A4 > >2C9 > 2C8 > 2A6 > 1A2 > 2B6 > 2D6 > 2C19 > 2C18 > 1A1 at low TFM concentration, whilst at high TFM concentration it was 1A2 > >2C9 = 3A4 = 2A6 > 2C19 > 2B6 = 2C8 > 2D6 > 1A1 > 2C18. Experiments with HLMs confirmed the involvement of the most relevant CYPs in the presence of specific chemical inhibitors with a catalytic efficiency (Cliapp) lower by an order of magnitude compared with recombinant enzymes. Esterases were also relevant to the overall TFM kinetics and metabolism, with catalytic efficiency higher than that of CYPs. It is foreseen that such isoform-specific information in humans will further support in silico models for the refinement of the human risk assessment of single pesticides or mixtures.

Dispersive Solid-Liquid Extraction Coupled with LC-MS/MS for the Determination of Sulfonylurea Herbicides in Strawberries

The monitoring of food quality and safety requires a suitable analytical method with simultaneous detection in order to control pesticide and herbicide residues. In this study, a novel analytical method, referred to as “dispersive solid–liquid extraction”, was applied to monitor seven sulfonylurea herbicides in strawberries. This method was optimized in terms of the amount of C₁₈ and the volume of added water, and it was validated through satisfactory linearities (R² > 0.99), recoveries of 70% to 84% with acceptable precisions, and limits of quantification lower than the maximum residue limits for the seven sulfonylurea herbicides in strawberries. The cleanup efficiency of the dispersive solid–liquid extraction technique was compared to that of the QuEChERS- (“quick, easy, cheap, effective, rugged and safe”) based method with dispersive solid phase extraction. The recoveries of the former were found to be comparable to those involving QuEChERS C₁₈ cleanup (recoveries of 74%–87%). The method was used to determine sulfonylurea herbicide residues in ten strawberry samples. None of the samples had herbicide residues higher than that of limit of quantifications (LOQs) or maximum residue limits (MRLs). The results suggest that the dispersive solid–liquid extraction method combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) is effective for the analysis of sulfonylurea herbicide residues in strawberries.

Chitin synthesis inhibitors promote liver cancer cell metastasis via interfering with hypoxia-inducible factor 1α

Chitin synthesis inhibitors (CSIs), as alternatives to conventional insecticides, have been in worldwide demand in recent years. However, little attention has been paid to the potential ecological safety and health risks of CSIs, especially their abilities to interfere with nonsexual hormone receptors such as hypoxia-inducible factor 1α (HIF-1α). In this work, we conducted a systematic study regarding the influence of CSIs on HIF-1α-related liver cancer cell metastasis. The dual-luciferase reporter gene assay revealed that two of fourteen CSIs exhibited dose-response HIF-1α agonistic activities at noncytotoxic concentrations with relative luciferase activity (RLA) values of 25.6% for diflubenzuron (DFB) and 20.9% for triflumuron (TFM). Following this result, in vitro bioassays demonstrated that both DFB and TFM stimulated HepG2 cell migration and invasion. This action was associated with the varied expression levels of genes involved in epithelial-to-mesenchymal transition (EMT) activation and extracellular matrix (ECM) degradation, such as the upregulation of fibronectin (FN1) and matrix metalloproteinase-2 (MMP-2) and the suppression of E-cadherin (E-cad) and tissue inhibitor of metalloproteinases-2 (TIMP-2). Moreover, changes in these EMT and ECM phenotype markers were dramatically blocked by a HIF-1α inhibitor (KC7F2), which further verified the involvement of HIF-1α in CSI-induced HepG2 cell metastasis. For the first time, our findings reveal that CSIs play crucial roles in promoting the metastasis of human liver cancer cells and that HIF-1α is potentially responsible for these changes.

Organic Solvent as Internal Standards for Quantitative and High-Throughput Liquid Interfacial SERS Analysis in Complex Media

Liquid-state interfacial nanoparticle arrays for surface-enhanced Raman scattering (SERS) promises a practical, substrate-free, and rapid analysis but faces a great challenge to develop a batch and uniform fabrication strategy with stable internal standards (IS) because of the difficulties in precisely locating both the IS tags and analytes in the same local structure under the harsh conditions of biphasic liquid interface. Here, we develop a fast batch preparation of self-ordered dense Au nanoparticle (GNP) arrays on cyclohexane/water biphasic interface in 96-well plates with the assist of acetone as the phase-crossing inducer. The acetone can extract the pesticide molecules via a simple dipping sample peels and can rapidly capture and locate the pesticide molecule into the plasmonic hotspots. Meanwhile, this phase-crossing solvent, acetone itself, generates stable SERS signal and is used as the IS tags to calibrate the signal fluctuation. This platform presents an excellent uniformity with a relative standard deviation (RSD) of 5.9% compared to the RSD of 14.5% without the IS's correction and a good sensitivity with a limit of detection (LOD) of 1 nM thiram. This high-throughput strategy for analyzing pesticide residues at fruit peels reached detection levels of nanograms per square centimeter (ng/cm²). Combined with the 96-well plates, this platform greatly facilitates the self-assembly and multiplex sampling. The self-ordered arrays at two immiscible phases interface evidenced the detection of both the oil-soluble thiabendazole and the water-soluble thiram molecules and also realized the multiplex and two-phase detection of these two pesticides. This platform offers vast possibilities for on-site sensing of various analytes and paves a new way for the quantitative and high-throughput SERS analyzer just as convenient as the microplate reader.

In vitro PPARγ agonistic potential of chitin synthesis inhibitors and their energy metabolism-related hepatotoxicity

The extensive use of chitin synthesis inhibitors (CSIs) in integrated pest management programs has a detrimental effect on the surrounding environment. Recent studies reveal that CSIs may affect non-target organisms at sublethal concentrations, highlighting the need for further ecological and health risk investigations of these compounds. In this study, we characterized the peroxisome proliferator-activated receptor γ (PPARγ) agonistic activity of fourteen CSIs in HepG2 cells using an in vitro reporter gene assay. Five of the tested CSIs showed remarkable PPARγ-mediated transactivation, and the relative agonistic potencies were diflubenzuron>chlorfluazuron>flucycloxuron>noviflumuron>flufenoxuron based on REC₂₀ values. In addition, molecular docking indicated that different interactions may stabilize ligand binding to PPARγ. Next, we clarified that sublethal concentration of diflubenzuron caused a shift in cellular energy metabolism from the aerobic tricarboxylic acid (TCA) cycle to anaerobic glycolysis and this process was associated with the activation of PPARγ. These findings suggest that CSIs act as PPARγ agonists and exert diverse hepatotoxic effects by disrupting energy metabolism at sublethal concentrations.

Multi-pesticides residue analysis of grains using modified magnetic nanoparticle adsorbent for facile and efficient cleanup

A facile, rapid sample pretreatment method was developed based on magnetic nanoparticles for multi-pesticides residue analysis of grains. Magnetite (Fe₃O₄) nanoparticles modified with 3-(N,N-diethylamino)propyltrimethoxysilane (Fe₃O₄-PSA) and commercial C18 were selected as the cleanup adsorbents to remove the target interferences of the matrix, such as fatty acids and non-polar compounds. Rice was used as the representative grain sample for method optimization. The amount of Fe₃O₄-PSA and C18 were systematically investigated for selecting the suitable purification conditions, and the simultaneous determination of 50 pesticides and 8 related metabolites in rice was established by liquid chromatography-tandem mass spectrometry. Under the optimal conditions, the method validation was performed including linearity, sensitivity, matrix effect, recovery and precision, which all satisfy the requirement for pesticides residue analysis. Compared to the conventional QuEChERS method with non-magnetic material as cleanup adsorbent, the present method can save 30% of the pretreatment time, giving the high throughput analysis possible.

Potential hepatic toxicity of buprofezin at sublethal concentrations: ROS-mediated conversion of energy metabolism

Buprofezin is known for its broad-spectrum action and environmental safety. The popularity of buprofezin has raised concerns about its potentially adverse effects on human health and risk to the environment. In this study, we first identified the liver as one of the major organs in which buprofezin accumulated, and we detected a severe oxidative stress response. Next, we demonstrated that sublethal concentrations of buprofezin promoted the conversion of energy metabolism from the aerobic tricarboxylic acid (TCA) cycle and oxidative phosphorylation to anaerobic glycolysis. Importantly, reactive oxygen species (ROS) generation partially accounted for the shunting of the energy metabolism through the buprofezin-mediated inhibition of cytochrome c oxidase activity. ROS directly perturbed the activities of several key TCA cycle enzymes, stimulated glycolysis, and indirectly disturbed the activity of the respiratory chain complex by altering mitochondrial DNA (mtDNA). These findings clarify the potential mechanisms of buprofezin toxicity and provide biomarkers for buprofezin-mediated hepatotoxicity at sublethal concentrations.

Burrowing mayfly Ephemera orientalis (Ephemeroptera: Ephemeridae) as a new test species for pesticide toxicity

The potential of mayfly Ephemera orientalis McLachlan eggs and first-instar larvae in ecotoxicological testing was investigated. Both stages of E. orientalis showed high tolerance to various environmental variables, such as water temperature, pH, water hardness, and dissolved organic carbon. Toxicological assays were conducted with three insecticides (emamectin benzoate, endosulfan, and cypermethrin), one fungicide (mancozeb), and one herbicide (paraquat dichloride). The two toxicity endpoints for the assay were the 14-day egg median hatching rate (EHC50) in static and renewal exposure systems and 24-h median larval mortality (LC50). Cypermethrin was the most toxic to both eggs (EHC50 in static system = 36.9 μg/L; EHC50 in renewal system < 0.15 μg/L) and larvae (LC50 = 4.5 μg/L), and paraquat dichloride was the least toxic to eggs (EHC50 in static system = 54,359.8 μg/L; EHC50 in renewal system = 49541.3 μg/L) and larvae (LC50 = 9259.5 μg/L). The results were compared to literature data of Daphnia magna Straus and Cloeon dipterum Linnaeus to determine its relative sensitivity to pesticides. These three species had different toxicities to the tested pesticides, especially according to the exposure system. E. orientalis eggs in the static system were found to be less sensitive were D. magna and C. dipterum, but eggs in the renewal system and larvae had similar or higher sensitivities to the tested pesticides. The results revealed that this species has potential for use in ecotoxicological testing of pesticides. Because of its geographic distribution, E. orientalis may be used as an alternative or complementary test species for ecotoxicological studies in Northeast Asian countries, where natural populations of the international standard species, D. magna, are rarely found.

Rapid Isolation and Determination of Flavones in Biological Samples Using Zinc Complexation Coupled with High-Performance Liquid Chromatography

Chlorophyll-type contaminants are commonly encountered in the isolation and determination of flavones of plant aerial plant parts. Heme is also a difficult background substance in whole blood analysis. Both chlorophyll and heme are porphyrin type compounds. In this study, a rapid method for isolating flavones with 5-hydroxyl or ortho-hydroxyl groups from biological samples was developed based on the different solubilities of porphyrin-metal and flavone-metal complexes. It is important that other background substances, e.g., proteins and lipids, are also removed from flavones without an additional processing. The recoveries of scutellarin, baicalin, baicalein, wogonoside and wogonin, which are the primary constituents of Scutellaria baicalensis (skullcaps) were 99.65% ± 1.02%, 98.98% ± 0.73%, 99.65% ± 0.03%, 97.59% ± 0.09% and 95.19% ± 0.47%, respectively. As a sample pretreatment procedure, this method was coupled to high-performance liquid chromatography (HPLC) with good separation, sensitivity and linearity and was applied to determine the flavone content in different aerial parts of S. baicalensis and in dried blood spot samples.

Multiresidue Method for Determination of 183 Pesticide Residues in Leeks by Rapid Multiplug Filtration Cleanup and Gas Chromatography-Tandem Mass Spectrometry

This study reports the development of a novel multiplug filtration cleanup (m-PFC) procedure for analysis of pesticide residues in leek samples followed by gas chromatography-tandem mass spectrometry detection. The leek samples were initially purified following the dispersive solid-phase extraction with different sorbents to determine the most suitable proportioning of sorbent materials; then, the m-PFC method was carried out by applying the streamlined procedure with syringes. Average recoveries of most pesticides were in the range from 70.2 to 126.0% with the relative standard deviation < 20% with the m-PFC process. The limits of detection were 0.03-3.3 μg kg(-1). The limits of quantification were 0.1-10 μg kg(-1). The m-PFC process is convenient and time-efficient, taking just a few seconds per sample. Finally, the developed method was successfully applied to the determination of pesticide residues in market samples. In that analysis, 35 pesticides were detected in 29 samples, with values ranging from 2.0 to 9353.1 μg kg(-1).

Human health risk assessment of organophosphorus pesticide in rice crop from selected districts of Anzali International Wetland basin, Iran

Low fertility in rice caused by Chilo suppressalis has led to the use of diazinon to control this pest. Residue of pesticide could penetrate products and also food which can affect public health. The aim of this research was to determine health risk assessment of organophosphorus (OP) pesticide in rice, a strategic crop in Iran. Ninety rice samples were collected from 30 points during harvesting seasons from Rasht Area, Guilan Province, Iran from which 30 samples were prepared. The concentration of diazinon, the most common pesticide used in the study area, was determined by high-performance liquid chromatography. The result indicated that the total average of diazinon in rice samples (31.91 mg/kg) is by far higher than the maximum residue limit recommended by the European Union. According to the results, EDAI was 0.051 mg/kg day, while health risk index in rice was 10.2. Results showed that there is a health risk associated with the lifetime consumption of rice polluted by OP pesticide in the study area.

Acute and short-term developmental toxicity of cyhalofop-butyl to zebrafish (Danio rerio)

Cyhalofop-butyl is an aryloxyphenoxypropionate post-emergence herbicide widely used around the world in agriculture. The acute toxicity of cyhalofop-butyl to embryos, larvae (12 and 72 h post-hatching), and adult zebrafish, as well as the short-term developmental toxicity of cyhalofop-butyl to embryo and sac-fry stages, was tested. The results showed that the 96-h LC50 values of cyhalofop-butyl to embryos, 12 h post-hatching larvae, 72 h post-hatching larvae, and adult fish were 2.03, 0.58, 1.42, and 3.49 mg/L, respectively, suggesting zebrafish early life stages were more sensitive to cyhalofop-butyl than adult stage. Cyhalofop-butyl would inhibit the spontaneous movement, heartbeat, hatching rate of embryos, and the body length of surviving larvae of zebrafish at 1.00 mg/L or higher concentrations. Morphological abnormalities, including pericardial edema, yolk sac edema, deformation of tail, and deformation of spine, were induced by cyhalofop-butyl. The results indicated that cyhalofop-butyl had significant negative impacts on zebrafish at different life stages, and spontaneous movement and hatching rate were sensitive endpoints for assessing short-term developmental toxicity of cyhalofop-butyl.

Evaluation of alternative sorbents for dispersive solid-phase extraction clean-up in the QuEChERS method for the determination of pesticide residues in rice by liquid chromatography with tandem mass spectrometry

Many compounds are used for pest control during the production and storage of rice, making it necessary to employ multiclass methods for pesticide residues determination. For this purpose, QuEChERS-based methods are very efficient, fast and accurate, and improvements in the clean-up step are important, especially for complex matrices, like cereals. In this work, different sorbents such as chitosan, florisil(®) , alumina, diatomaceous earth, graphitized carbon black, besides the commonly used primary secondary amine and octadecylsilane, were evaluated for dispersive solid-phase extraction clean-up in acetate-buffered QuEChERS method for the determination of residues of 20 representative pesticides and one metabolite in rice by liquid chromatography coupled to tandem mass spectrometry. The sorbent C18 presented the best results, however, chitosan showed similar results, and the best performance among the unconventional sorbents evaluated. The method limit of quantification, attending accuracy (70-120% recovery) and precision (RSD ≤20%) criteria, ranged from 5 to 20 μg/kg. Results showed that chitosan is an effective alternative to reduce analysis costs, maintaining the method reliability and accuracy.

Polychlorinated biphenyl (PCBs) in rice grains and straw; risk surveillance, congener specific analysis, distribution and source apportionment from selected districts of Punjab Province, Pakistan

The current study presents health risk surveillance by investigating the levels of polychlorinated biphenyls (PCBs) in rice (Oryza sativa L.) grains and rice straw. Samples were collected from four districts (Okara, Sahiwal, Lahore and Sheikhpura) of Punjab Province, Pakistan for congener specific analysis of PCBs, and to observe the spatial distribution pattern and point sources. Level of Σ30 PCB (ng g(-1)) in rice grains and rice straw ranged from 4.31 to 29.68 and 6.11-25.35, respectively. Tetra-CBs were found predominant in rice straw (49%) and grains (38%) over other PCB homologs. No significant variation (P>0.005) was observed for most of the screened PCBs congeners except, PCB-66, -77, -60, -101, -74, -138, -153 and -105 in rice grains and PCB-66 in rice straw. Reported toxicity equivalency (TEQ) values for dioxin like PCBs in rice grains were found lower than the previously published reports from Asian countries, however higher TEQ values are reported for rice straw in this study. Health was found at risk of cancer among one in million by consumption of the study area food stuffs, though no considerable carcinogenic risks to human health was found.

Direct determination of methyl parathion insecticide in rice samples by headspace solid-phase microextraction-gas chromatography-mass spectrometry

BACKGROUND

The organophosphorus insecticides, especially those based on methyl parathion as active principle, have been used extensively in the protection of rice in Maranhão State, in the north-east of Brazil. This paper describes the optimisation of a solid-phase microextraction (SPME) procedure in confined atmosphere (headspace, HS) for the determination of methyl parathion in rice organic samples by gas chromatography with mass spectrometry detection (GC/MS).

RESULTS

The proposed HS-SPME-GC/MS method has been shown to be appropriate for direct analysis of the insecticide in polished rice, with satisfactory results for the following parameters: linearity (correlation coefficient 0.9985), sensitivity (LOD and LOQ of 0.026 and 0.078 µg kg(-1) respectively), precision (coefficients of variation between 6.1 and 22.4%) and accuracy (recoveries varying from 73.2 to 90.0%). Although the efficiency of the proposed GC/MS does not differ statistically (P < 0.05) from the conventional GC/NPD method, given its low cost, speed and also the fact that a minimum volume of toxic effluent is generated, this method can be considered an on-line procedure based on green chemistry.

CONCLUSIONS

Thus, the analytical methodology satisfies the minimum requirements for control of residues of such insecticides in rice samples destined for human consumption.

Direct Immersion Solid-Phase Microextraction with Matrix-Compatible Fiber Coating for Multiresidue Pesticide Analysis of Grapes by Gas Chromatography-Time-of-Flight Mass Spectrometry (DI-SPME-GC-ToFMS)

A fast and sensitive direct immersion-solid-phase microextraction-gas chromatography-time-of-flight mass spectrometry (DI-SPME-GC-ToFMS) method for the determination of multiresidue pesticides in grapes employing a PDMS-modified PDMS/DVB coating was developed utilizing multivariate approaches for optimization of the most important factors affecting SPME performance. A comprehensive investigation of appropriate internal standards using a bottom-up approach led to the selection of suitable compounds that adequately covered a range of 40 pesticides pertaining to various classes. The validated method yielded good accuracy, precision, and sensitivity and has been successfully applied to the analysis of commercial samples. With regard to the limitations of the proposed method, the DI-SPME method did not provide a satisfactory performance toward more polar pesticides (e.g., acephate, omethoate, dimethoate) and highly hydrophobic pesticides, such as pyrethroids. Despite the challenges and limitations encountered by this method, the practical aspects of the PDMS-modified coating demonstrated here create new opportunities for SPME applied in food analysis.

Human health risk assessment, congener specific analysis and spatial distribution pattern of organochlorine pesticides (OCPs) through rice crop from selected districts of Punjab Province, Pakistan

To evaluate the screening level risk assessment of OCPs in rice (Oryza sativa L.) straw (n=20) and rice grains (n=20), samples were collected from different districts of Punjab Province, Pakistan. ∑OCPs' levels (ng g(-1)) in rice straw and grains ranged from 3.63 to 39.40, 2.72 to 49.89, respectively. DDTs were found predominant over the other detected OCP isomers followed by HCH and heptachlor. Results of one way ANOVA reflected no significant difference for OCPs' levels among sampling sites, except heptachlor for rice grains. ∑OCPs' concentration in rice straw samples was exceeding the minimal residual levels (MRLs) (Australian and Japanese). Results of dietary intake and risk assessment suggested that rice straw is not safe for animals to consume as fodder. Human health was suggested to have some carcinogenic risks by consumption of rice grains, however, no considerable hazardous risk (non-carcinogenic) to human health was found.