Application of Box–Behnken design to optimize multi-sorbent solid phase extraction for trace neonicotinoids in water containing high level of matrix substances

Imidacloprid affects human cells through mitochondrial dysfunction and oxidative stress

Given their relatively low persistence and mammalian toxicity, neonicotinoid pesticides have been extensively used worldwide and are omnipresent in the environment. Recent studies have shown that neonicotinoids may pose adverse effects on non-target organisms other than the known neurotoxicity, raising emerging concerns that these insecticides might pose human health risk through additional toxicity pathways. In the present study, the mitochondria function, oxidative stress, DNA damages, and genes transcription levels were examined in the human neuroblastoma SH-SY5Y cells after 48-h exposure to imidacloprid at concentrations from 0.05 to 200 μmol/L. Results showed that imidacloprid induced mitochondrial dysfunction with the degradation of adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP) levels. In addition, imidacloprid caused oxidative stress by stimulating the generation of reactive oxygen species (ROS) and hydrogen peroxide (H2O2) via the disruption of calcium ion level and mitochondrial function. Ultimately, the oxidative stress continued to produce DNA damage and apoptosis in SH-SY5Y cells at imidacloprid concentrations above 47.6 μmol/L. Among the evaluated endpoints, ATP was the most sensitive, with a median activity concentration of 0.74 μmol/L. The 5 % hazard concentration of imidacloprid was estimated to be 0.69 μmol/L, which can be used as a threshold for human health risk assessment for imidacloprid. Collectively, our results provide an important support for further research on potential toxicity of neonicotinoids related to mitochondrial toxicity in humans.

A Recyclable Luminescent MOF Sensor for On-Site Detection of Insecticide Dinotefuran and Anti-Parkinson's Drug Entacapone in Various Environmental and Biological Specimens

The monitoring and precise determination of pesticides and pharmaceutical drugs and their residues have become increasingly important in the field of food safety and water contamination issues. Herein, a fluorescent aluminium MOF-based sensor (1) was developed for the selective recognition of neonicotinoid insecticide dinotefuran and anti-Parkinson's drug entacapone. Guest-free MOF 1' exhibited ultra-fast response (<5 s) and ultra-low detection limits of 2.3 and 7.6 nM for dinotefuran and entacapone, which are lower than the previously reported MOF-based sensors. In the presence of other competitive analytes, great selectivity was achieved towards both analytes. The probe was recyclable up to five cycles. The sensing ability was explored towards entacapone in human serum, urine and dinotefuran in real soil, rice, honey samples, different fruits, vegetables, real water specimens and a wide range of pH media. A low-cost, handy MOF-based polymer thin-film composite (1'@PVDF-PVP) was developed for the on-site detection of dinotefuran and entacapone. Mechanistic studies involving analytical techniques and theoretical calculations suggested that FRET and PET are the probable reasons for entacapone sensing whereas IFE is responsible for dinotefuran detection. The entire work presents a low cost, multi-use photoluminescent sensor of entacapone and dinotefuran to address the environmental pollution.

Removal of neonicotinoid insecticides in a large-scale constructed wetland system

Neonicotinoid insecticides are among the most used insecticides and their residues are frequently found in surface water due to their persistence and mobility. Neonicotinoid insecticides exhibit toxicity to a wide range of aquatic invertebrates at environmentally relevant levels, and therefore their contamination in surface water is of significant concern. In this study, we investigated the spatiotemporal distribution of six neonicotinoids in a large wetland system, the Prado Wetlands, in Southern California, and further evaluated the wetlands' efficiency at removing these insecticides. Total neonicotinoid concentrations in water ranged from 3.17 to 46.9 ng L-1 at different locations within the wetlands, with imidacloprid and dinotefuran among the most detected. Removal was calculated based on concentrations as well as mass flux. The concentration-based removal values for a shallow pond (vegetation-free), moderately vegetated cells, densely vegetated cells, and the entire wetland train were 16.9%, 34.2%, 90.2%, and 61.3%, respectively. Principal component analysis revealed that pH and temperature were the primary factors affecting neonicotinoids removal. Results from this study demonstrated the ubiquitous presence of neonicotinoids in surface water impacted by urban runoff and wastewater effluent and highlighted the efficiency of wetlands in removing these trace contaminants due to concerted effects of uptake by wetland plants, photolysis, and microbial degradation.

Design of experiments (DoE) to develop and to optimize extraction of psychoactive substances

The design of experiments (DoE) method was employed to optimize the adsorption processes of seven psychoactive substances in magnetic solid phase extraction. Fe₃O₄/GO/ZIF-8 was utilized as an adsorbent for the efficient extraction of psychoactive substances from environmental water samples. The analytes were ephedrine, methylephedrine, amphetamine, methamphetamine, morphine, papaverine, and thebaine, which were determined by ultrahigh performance liquid chromatography-tandem mass spectrometry. Plackett-Burman design was employed to identify the significant factors responsible for adsorption, and Box-Behnken design was used for further optimization to obtain the optimum values for each variable. The predicted and experimental values were found to be in good agreement. The coefficient of determination (R²) values of 0.9500-0.9976 indicated that the model was significant. The linear ranges were 1-100 ng mL^-1, and the correlation coefficient was good (r² ≥ 0.995). The EF with values of about 2.5 was obtained with recoveries in the range of 74.92-94.47%. The limits of detection (LOD) and limits of quantification (LOQ) were 0.086-0.353 ng mL^-1 and 0.286-1.175 ng mL^-1, respectively. The intra-day and inter-day RSDs were in the range of 0.17-1.87% and 0.06-2.21%, respectively. By using the DoE method, the errors associated with inferring the influence and interaction between various factors can be reduced. The combination of MSPE and DoE improves the recovery, precision, and simultaneous detectability of the target analytes. It has a high potential for psychoactive substance analysis in environmental water.

A comprehensive review on the pretreatment and detection methods of neonicotinoid insecticides in food and environmental samples

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The metabolism and residue status of neonicotinoids were briefly summarized in this work.

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Sample pretreatment techniques for the analysis of neonicotinoids were critically discussed.

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The commonly used detection methods for neonicotinoids residues were also pointed out.

In recent years, the residues of neonicotinoid insecticide in food and environmental samples have attracted extensive attention. Neonicotinoids have many adverse effects on human health, such as cancer, chronic disease, birth defects, and infertility. They have substantial toxicity to some non-target organisms (especially bees). Hence, monitoring the residues of neonicotinoid insecticides in foodstuffs is necessary to guarantee public health and ecological stability. This review aims to summarize and assess the metabolic features, residue status, sample pretreatment methods (solid-phase extraction (SPE), Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS), and some novel pretreatment methods), and detection methods (instrument detection, immunoassay, and some innovative detection methods) for neonicotinoid insecticide residues in food and environmental samples. This review provides detailed references and discussion for the analysis of neonicotinoid insecticide residues, which can effectively promote the establishment of innovative detection methods for neonicotinoid insecticide residues.

Green synthesis of novel magnetic porous organic polymer for magnetic solid phase extraction of neonicotinoids in lemon juice and honey samples

Natural rutin with abundant hydroxyl groups was used as a green monomer to synthesize hydroxyl-functional magnetic porous organic polymer (named Rut-MOP) through environmentally-benign diazo-coupling reaction for the first time. The Rut-MOP displayed high extraction capability for neonicotinoid insecticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid). Thus, a Rut-MOP based magnetic solid-phase extraction method combined with high performance liquid chromatography was established for sensitive determination of neonicotinoid insecticides in lemon juice and honey samples. Under optimized conditions, the linear response of neonicotinoids was 0.1-100.0 ng mL^-1 for lemon juice and 8.0-1000.0 ng g^-1 for honey. The limits of detection (S/N = 3) were 0.03-0.04 ng mL^-1 and 2.5-3.0 ng g^-1 for lemon juice and honey, respectively. The method recoveries were 82-118% with the relative standard deviations of 1.9-7.6%. The results demonstrate that the Rut-MOP based method can be served as a good alternative for the sensitive analysis of neonicotinoid insecticides in lemon juice and honey.

Nanofibrous Online Solid-Phase Extraction Coupled with Liquid Chromatography for the Determination of Neonicotinoid Pesticides in River Waters

Polymeric nano- and microfibers were tested as potential sorbents for the extraction of five neonicotinoids from natural waters. Nanofibrous mats were prepared from polycaprolactone, polyvinylidene fluoride, polystyrene, polyamide 6, polyacrylonitrile, and polyimide, as well as microfibers of polyethylene, a polycaprolactone nano- and microfiber conjugate, and polycaprolactone microfibers combined with polyvinylidene fluoride nanofibers. Polyimide nanofibers were selected as the most suitable sorbent for these analytes and the matrix. A Lab-In-Syringe system enabled automated preconcentration via online SPE of large sample volumes at low pressure with analyte separation by HPLC. Several mat layers were housed in a solvent filter holder integrated into the injection loop of an HPLC system. After loading 2 mL sample on the sorbent, the mobile phase eluted the retained analytes onto the chromatographic column. Extraction efficiencies of 68.8–83.4% were achieved. Large preconcentration factors ranging from 70 to 82 allowed reaching LOD and LOQ values of 0.4 to 1.7 and 1.2 to 5.5 µg·L⁻¹, respectively. Analyte recoveries from spiked river waters ranged from 53.8% to 113.3% at the 5 µg·L⁻¹ level and from 62.8% to 119.8% at the 20 µg·L⁻¹ level. The developed methodology proved suitable for the determination of thiamethoxam, clothianidin, imidacloprid, and thiacloprid, whereas matrix peak overlapping inhibited quantification of acetamiprid.

Persistence and vertical distribution of neonicotinoids in soils under different citrus orchards chrono sequences from southern China

Continual input of neonicotinoid insecticides occurs in the citrus orchards from southern China. However, it is still unknown about the variations in the distribution and accumulation of neonicotinoids in soil profiles along a long-term chronosequence of cultivation and the driving factors contributing to these shifts. Here, changes of neonicotinoids in the 0-100 cm soil profiles with distinct orchard cultivation age (1, 10, and 20 years) were investigated, and their related factors were further determined. The results showed that the total levels of five target neonicotinoids (∑₅NEOs) in the soil profiles were in the range of 0-25.76 ng/g dw. Imidacloprid was the most dominating neonicotinoid, followed by thiamethoxam. We observed higher neonicotinoid accumulations in the soil profiles from the citrus orchards after 10 and 20 years of cultivation. Neonicotinoids migrated deeper into the soil profiles in orchards with a longer time since cultivation. Imidacloprid, thiamethoxam, and the total amount of neonicotinoid (∑₅NEOs) were mainly affected by the cultivation age of citrus orchards (accounting for 58.9% variance; P < 0.001); whereas clothianidin, acetamiprid, and thiacloprid were mainly influenced by soil depths (accounting for 66.9-85.2% variance; P < 0.05). Redundancy analyzes further indicated that the enhanced accumulation of neonicotinoids was mainly correlated with the increase of soil organic carbon (SOC) content and soil porosity, and the reduction of bulk density in the profiles of citrus orchards with increasing cultivation age. This study highlights the finding that we should give more concerns about the contamination and ecological risks of neonicotinoids in the orchards with a long cultivation age.

Dummy molecularly imprinted membranes based on an eco-friendly synthesis approach for recognition and extraction of enrofloxacin and ciprofloxacin in egg samples

In this work, novel dummy molecularly imprinted membranes (MIMs) were fabricated using the nylon-66 (NY-66) membranes as the subtracts based on an eco-friendly "sandwich" technology with less consumption of organic reagents at mild conditions for recognition and extraction of enrofloxacin (ENR) and ciprofloxacin (CIP) in egg samples. The prepared MIMs were characterized by SEM, ATR-FTIR and TGA, showing the successful construction of uniform and porous polymers on the surface of membranes. A series of adsorption affinity tests were investigated, indicating the prepared materials had specific recognition capacity and excellent stability as novel sorbents. Furthermore, Box-Benhnken design (BBD) and single factor investigations were applied to optimize pretreatment procedures, coupling with Ultra High Performance Liquid Chromatograph (UHPLC) detection. The method showed a good correlation (r²>0.9999) within the linear range of 5.0~5000.0 µg kg^-1, and limit of detection (LOD) of ENR and CIP were 0.3 and 0.7 µg kg^-1, respectively. The mean recovery ranged from 84.5% to 97.0% within relative standard deviations (RSDs) of 10.2%. Finally, ENR and CIP were not detected in 3 batches of egg samples. The current study developed the dummy MIMs as sorbents combined with UHPLC analysis for extraction and detection of target analytes in food matrices.

Tracing neonicotinoid insecticides and their transformation products from paddy field to receiving waters using polar organic chemical integrative samplers

Neonicotinoid insecticides are ubiquitous in surface water worldwide, yet the transportation and transformation of these compounds in aquatic environment remain unclear. In the present study, polar organic chemical integrative sampler with mixed-mode adsorbents (POCIS-MMA) was developed for simultaneously tracing environmental fate of seven neonicotinoids and 10 transformation products (TPs) from a paddy field to receiving waters in Poyang Lake basin, Jiangxi, China. All neonicotinoids (5.20 ± 0.75‒866 ± 143 ng/L) and seven TPs (116 ± 4‒334 ± 78 ng/L) were detected, demonstrating widespread occurrence of these insecticides in aquatic environment. Dinotefuran (up to 802 ± 139 ng/L) and its TP, 1-methyl-3- (tetrahydro-3-furylmethyl) guanidium dihydrogen (DN) (103 ± 4‒320 ± 76 ng/L) were the dominant neonicotinoids and TPs with mean concentrations of 200 ± 296 and 208 ± 58 ng/L, respectively. Spatial attenuation of neonicotinoids stretched downstream along the rivers, while TP concentrations firstly increased (D1‒S6) and then kept constant (S7‒S16) from upstream to downstream. Though paddy field was the main source of neonicotinoids, additional input sources downstream were identified by analyzing the composition of neonicotinoids and their TPs. Our study highlighted the applicability of POCIS-MMA passive sampling to investigate the transportation and transformation of neonicotinoids in agricultural waterways.

Zeolitic imidazolate framework-8 decorated with gold nanoparticles for solid-phase extraction of neonicotinoids in agricultural samples

A composite built with aminated zeolitic imidazolate framework and gold nanoparticles (AuNPs) for solid-phase extraction (SPE) of neonicotinoids in agricultural samples is presented. The composite was prepared through the assembly of AuNPs onto the surface of metal-organic framework based on the strong interaction between the amino group and AuNP. These metallic surfaces provided additional interactions based on the affinity of amino and cyano groups present in the target compounds. The composite was characterized by scanning electron microscopy, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and surface area measurements. Regarding the SPE protocol, several parameters that can influence the extraction performance were optimized, such as sample volume or composition of elution solvent, among others. After elution, the analytes were determined via HPLC with diode-array detection. Under the selected conditions, satisfactory recoveries of five pesticides (thiamethoxan, clothianidin, imidacloprid, acetamiprid, and thiacloprid) were obtained (between 80 and 110%) in real samples, whereas the limits of detection ranged from 0.019 to 0.041 μg L^-1 in aqueous samples and 0.3 to 0.8 μg g^-1 in solid samples.

Polysaccharides and polyphenol in dried Morinda citrifolia fruit tea after different processing conditions: Optimization analysis using response surface methodology

The increasing popularity of Morinda citrifolia has many medical and health benefits because of its rich polysaccharides (PSC) and polyphenols (PPN). It has become popular to brew the dry M. citrifolia fruit slice as tea in some regions of China. In this study, optimize the extraction parameters of M. citrifolia fruit tea polysaccharides and polyphenols using response surface methodology. The results indicated the highest PSC yield of 17% at 46 °C for 11 min and the ratio of water/M. citrifolia fruit powder was 78 mL/g. The optimum extraction of PPN was at 95 °C for 10 min and the ratio of water/M. citrifolia fruit powder 90 mL/g, with 8.93% yield. Using dry M. citrifolia fruit slices as a tea is reported for the first time. Based on the results, the maximum level of PSC can be obtained under condition by infusing about four dried M. citrifolia fruit slice with average thickness and size in warm boiled water for 11 min, taking a 300 mL cup (300 mL of water) for example. The maximum level of PPN can be obtained by adding three slices of dried M. citrifolia fruit slice to boiled water for 10 min. Considering the powder used in our study, the further pulverization of cutting into powder is more conducive to material precipitation. This study provides a scientific basis for obtaining PSC and PPN from dry M. citrifolia fruit slice tea by brewing.

Recyclable Luminescence Sensor for Dinotefuran in Water by Stable Cadmium-Organic Framework

Due to the widespread use of dinotefuran around the world, its impact on food and environmental safety has aroused great concern, and the establishment of a rapid and convenient approach for dinotefuran detection is necessary but challenging. Herein, we synthesized a unique three-dimensional framework {[(CH₃)₂NH₂]₂[Cd₃(BCP)₂]·10H₂O·3.5DMF}_n (1). Single-crystal X-ray analysis indicates that 1 possesses a 4,8-connected anion framework that corresponds to alb topology, with a one-dimensional rectangular channel along the c-axis with the size of 4 Å × 10 Å. Compound 1 displays satisfactory solvent and thermal stability. Luminescent investigations reveal that 1 can selectively detect dinotefuran by fluorescence quenching among other pesticides, displaying excellent anti-interference performance with common ions in water. Importantly, the limit of detection is as low as 2.09 ppm, which is far below the residual concentration of the U.S. food standard. A fluorescence quenching mechanism study shows that there exists competitive energy absorption and static quenching processes. To our knowledge, 1 is the first MOF-based fluorescence probe for dinotefuran detection.

Joint toxicity of imidacloprid and azoxystrobin to Chironomus dilutus at organism, cell, and gene levels

Pesticides occur in the environment as mixtures, yet the joint toxicity of pesticide mixtures remains largely under-explored and is usually overlooked in ecological risk assessment. In the current study, joint toxicity of a neonicotinoid insecticide (imidacloprid, IMI) and a strobilurin fungicide (azoxystrobin, AZO) was investigated with Chironomus dilutus over a wide range of concentrations and at different effect levels (organism, cell, and gene levels). The two pesticides, both individually and in combination, were found to induce oxidative stress and cause lethality in C. dilutus. Median lethal concentrations for IMI and AZO were 3.98 ± 1.17 and 52.9 ± 1.1 μg/L, respectively. Mixtures of the two pesticides presented synergetic effects at environmentally relevant concentrations whilst antagonistic effects at high concentrations, showing concentration-dependent joint toxicity. Investigation on the expressions of 12 genes (cyt b, coi, cox1, cyp4, cyp12m1, cyp9au1, cyp6fv1, cyp315, gst, Zn/Cu-sod, Mn-sod, and cat) revealed that the two pesticides impaired mitochondrial respiration, detoxification, and antioxidant system of C. dilutus, and the joint effects of the two pesticides were likely due to an interplay between their respective influences on these physiological processes. Collectively, the synergistic effects of the two pesticides at environmentally relevant concentrations highlight the importance to incorporate combined toxicity studies into ecological risk assessment of pesticides.

Magnetic Solid Phase Extraction Based on Nanostructured Magnetic Porous Porphyrin Organic Polymer for Simultaneous Extraction and Preconcentration of Neonicotinoid Insecticides From Surface Water

In this study, a magnetic porphyrin-based porous organic polymer (MP-POP) nanocomposite was successfully synthesized according previous studies and applied as an adsorbent for simultaneous extraction and preconcentration of four neonicotinoid insecticides from surface river water. The MP-POP was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS), N2-adsorption/desorption analysis, Fourier Transform infrared spectroscopy (FTIR). The neonicotinoid insecticides were quantified using high performance chromatography coupled with diode array detector (HPLC-DAD). The MP-POP shown to have a high surface area, highly porous structure and strong affinity toward the investigated analytes. The adsorption capacities were 99.0, 85.5, 90.0, and 79.4 mg g-1 for acetamiprid, clothiandin, thiacloprid and imidacloprid, respectively. The influential parameters affecting the magmatic μ-solid phase extraction (M-μ-SPE) procedure were investigated using fractional factorial design and surface response methodology (RSM). Under optimum conditions, the method exhibited relatively low limit of detection in the range of 1.3-3.2 ng L-1, limit of quantification in the range of 4.3-11 ng L-1 and wide linearity (up to 600 μg L-1). The intraday and interday precision, expressed as the relative standard deviation (RSD) were <5%. The percentage recoveries for the four target analytes ranged from 91 to 99.3% for the spiked river water samples. The method was applied for determination of neonicotinoids in river water samples and concentrations ranged from 0 to 190 ng L-1.

Exposure Level of Neonicotinoid Insecticides in the Food Chain and the Evaluation of Their Human Health Impact and Environmental Risk: An Overview

Neonicotinoid insecticides (neonics) were the most rapidly growing class of insecticides over the past few decades, and are used mainly for vegetables, fruits, and grains. Although neonics exhibit lower toxicity in mammals and humans compared to traditional insecticides, increasing numbers of studies are demonstrating that neonics may accumulate in the food chain and environmental media. Long-term exposure to neonics may raise potential risks to animals and even to humans. The present report reviews the development, application, and prohibition of neonics in the farmland ecosystem, and summarizes the exposure level and harmful effects of these insecticides in the food chain. In addition, the present review analyzes and summarizes the evaluation of the human health impact and environmental risk of the neonics, and overviews the unresolved problems and future research directions in this field. The aim of the present report was to review the exposure level, potential toxicity, human health impact, and environmental risk assessment of neonics in various media in order to provide reliable technical support for strengthening the environmental and food safety supervision and green pesticide designing.

Toxicogenomics provides insights to toxicity pathways of neonicotinoids to aquatic insect, Chironomus dilutus

Neonicotinoid insecticides have posed a great threat to non-target organisms, yet the mechanisms underlying their toxicity are not well characterized. Major modes of action (MoAs) of imidacloprid were analyzed in an aquatic insect Chironomus dilutus. Lethal and sublethal outcomes were assessed in the midges after 96-h exposure to imidacloprid. Global transcriptomic profiles were determined using de novo RNA-sequencing to more holistically identify toxicity pathways. Transcriptional 10% biological potency values derived from ranked KEGG pathways and GO terms were 0.02 (0.01-0.08) (mean (95% confidence interval) and 0.05 (0.04-0.06) μg L^-1, respectively, which were more sensitive than those from phenotypic traits (10% lethal concentration: 0.44 (0.23-0.79) μg L^-1; 10% burrowing behavior concentration: 0.30 (0.22-0.43) μg L^-1). Major MoAs of imidacloprid in aquatic species were identified as follows: the activation of nicotinic acetylcholine receptors (nAChRs) induced by imidacloprid impaired organisms' nerve system through calcium ion homeostasis imbalance and mitochondrial dysfunction, which posed oxidative stress and DNA damage and eventually caused death of organisms. The current investigation highlighted that imidacloprid affected C. dilutus at environmentally relevant concentrations, and elucidated toxicity pathways derived from gene alteration to individual outcomes, calling for more attention to toxicity of neonicotinoids to aquatic organisms.

Distribution and ecological risk of neonicotinoid insecticides in sediment in South China: Impact of regional characteristics and chemical properties

Neonicotinoid insecticides have been frequently detected in surface water due to extensive use worldwide, however, little information is available for the regional characteristics and ecological risk of neonicotinoids in sediment. In the current study, six neonicotinoids were analyzed in 58 sediment samples from agricultural (vegetable and rice planting) and urban areas in South China. Neonicotinoids were ubiquitous in the sediments, with maximum, mean and median concentrations of 23.8, 4.21 and 2.73 ng·g^-1 dry weight, respectively. Neonicotinoids were detected more often and at higher concentrations in vegetable planting and urban areas while clothianidin and imidacloprid dominated neonicotinoid composition in the rice-planting area. Multiple correspondence analysis showed the distribution of sediment-bound neonicotinoids were significantly affected by crop type, distance to the source, and physicochemical properties of neonicotinoids. While more hydrophilic neonicotinoids tended to migrate to the streams, those with log K_ow > 0 are usually retained in the ditches near the treated fields. Neonicotinoids with shorter half-lives (acetamiprid and thiacloprid) were detected more frequently in vegetable planting areas, yet more persistent imidacloprid and clothianidin were more likely to be detected in rice planting areas. It was in accordance with application patterns of neonicotinoids in different crops. Environmental exposure distributions indicated that sediment-bound neonicotinoids, except for thiacloprid, posed considerable risk to aquatic invertebrates, which are important for ecological functioning of aquatic ecosystems, calling for better measures to control and manage of neonicotinoid risks.

Simultaneous analysis of current-use pesticides and their transformation products in water using mixture-sorbent solid phase extraction and high-performance liquid chromatography-tandem mass spectrometry

Pesticides have posed significant threats to aquatic ecosystems, yet little is known about their transformation products. The challenge is to simultaneously analyze various pesticides and transformation products in water as they have distinct physicochemical properties. A mix-mode solid phase extraction method was established to simultaneously analyze current-use pesticides and their transformation products using a mixture of hydrophile-lipophile balance, weak anion, and cation exchange resins (2:1:1, w/w/w) in combination with high-performance liquid chromatography and tandem mass spectrometry for chemical quantification. Neutral, acidic, and alkaline methanol were used as the elution solvent. Box-Behnken design was applied to optimize extraction conditions. Optimal conditions were as follows: sorbent mass, 200 mg; volume of elution solvent, 5 mL × 3; pH 4. The method was validated for compounds at concentrations from 20 to 1000 ng/L in different types of water samples, with recovery being from 43.5 ± 3.1 to 141 ± 35%. Low method detection limits (0.02-5.6 ng/L) implied that the developed method was sensitive. Finally, the method was applied to monitor current-use pesticides and their transformation products in natural waters. Frequent detection of transformation products of pesticides indicated that their contribution to aquatic risk should not be ignored.

Solid-phase microextraction of organophosphorous pesticides from food samples with a nitrogen-doped porous carbon derived from g-C3N4 templated MOF as the fiber coating

A nitrogen-doped metal organic framework (MOF) based porous carbon (C-(C₃N₄@MOF)) was produced by the carbonization of a graphitic carbon nitride (g-C₃N₄) templated MOF (NH₂-MIL-125). The C-(C₃N₄@MOF) was then coated on a stainless steel wire by sol-gel technique to serve as a solid-phase microextraction (SPME) fiber coating. The coated fiber was studied for the extraction of fourteen organophosphorous pesticides (OPPs) from different fruit and vegetable samples followed by gas chromatography-mass spectrometer (GC-MS) detection. The C-(C₃N₄@MOF) coated fiber exhibited a high extraction capability for the OPPs. Both single factor optimization and response surface analysis (Box-Behnken Design) methods were implemented to optimize the experiment conditions for the extraction. The results indicated that the linear response for the fourteen OPPs was in the range from 0.69 to 3000 ng g^-1 and the coefficients of determination (r²) ranged from 0.9981 to 0.9998. The limits of detection (LODs, S/N = 3) ranged from 0.23 to 7.5 ng g^-1. The method recoveries (R) of the fourteen OPPs for spiked fruit and vegetable samples were between 82.6% and 118%, with the relative standard deviations (RSDs) varying from 2.8% to 11.7%. The fiber can be reused over 100 times without a significant loss of extraction efficiency.

Applications of Green Chemistry Approaches in Environmental Analysis

Background:

Green chemistry is the application of methodologies and techniques to reduce the use of hazardous substances, minimize waste generation and apply benign and cheap applications.

Methods:

In this article, the following issues were considered: greener solvents and reagents, miniaturization of analytical instrumentation, reagent-free methodologies, greening with automation, greener sample preparation methods, and greener detection systems. Moreover, the tables along with the investigated topics including environmental analysis were included. The future aspects and the challenges in green analytical chemistry were also discussed.

Results:

The prevention of waste generation, atomic economy, use of less hazardous materials for chemical synthesis and design, use of safer solvents, auxiliaries and renewable raw materials, reduction of unnecessary derivatization, design degradation products, prevention of accidents and development of real-time analytical methods are important for the development of greener methodologies.

Conclusion:

Efforts should also be given for the evaluation of novel solid phases, new solvents, and sustainable reagents to reduce the risks associated with the environment. Moreover, greener methodologies enable energy efficient, safe and faster that reduce the use of reagents, solvents and preservatives which are hazardous to both environment and human health.

Determination of imidacloprid and its relevant metabolites in tomato using modified QuEChERS combined with ultrahigh-pressure liquid chromatography/Orbitrap tandem mass spectrometry

BACKGROUND

Red tomato processing is one of the leading industries in Xinjiang, but also the largest export industry. In the process of tomato planting, imidacloprid (IMI) is often used to kill aphids, which poses the risk of pesticide residue. However, as daily consumables, pesticide residue on tomatoes may cause a potential threat to human health. Therefore the aims of this research were to study the residue dynamics of IMI pesticides in tomatoes by monitoring field experiments and to investigate the fate of IMI and its metabolites under Xinjiang field conditions.

RESULTS

In the field trials, three different doses of IMI were sprayed on tomato during the fruit setting stage. Degradation of IMI and residue behaviors of its metabolites at different stages were systemically traced and evaluated by ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC/Q-Orbitrap MS). An accurate mass tool was used as the main method to identify the IMI metabolites. The improved method showed high efficiency in detecting IMI and 6-chlorinated nicotinic acid (6-CNA), being able to determine hazardous pesticides at trace levels. The fate of IMI in field tomato was investigated over 28 days. The metabolic mechanism of IMI in tomato is: OH products in the early stage and carbonyl products in the late stage.

CONCLUSION

Under natural conditions, pesticides in tomatoes will gradually decrease with time. In this process, olefin IMI is produced, but it is almost completely metabolized after 28 days. Therefore even 10 times the recommended dose of IMI pesticide will not endanger human health. © 2019 Society of Chemical Industry.

Occurrence and distribution of neonicotinoid insecticides in surface water and sediment of the Guangzhou section of the Pearl River, South China

Little information is available about the occurrence of neonicotinoid insecticides in surface water and sediment of the metropolitan regions around the rivers in China. Here we investigate the residual level of neonicotinoids in the Guangzhou section of the Pearl River. At least one or two neonicotinoids was detected in each surface water and sediment, and the total amount of neonicotinoids (∑₅neonics) in surface water ranged from 92.6 to 321 ng/L with a geometric mean (GM) of 174 ng/L. Imidacloprid, thiamethoxam and acetamiprid were three frequently detected neonicotinoids (100%) from surface water. As for the sediment, total concentration was varied between 0.40 and 2.59 ng/g dw with a GM of 1.12 ng/g dw, and acetamiprid and thiacloprid were the common sediment neonicotinoids. Western and Front river-route of the Guangzhou section of the Pearl River suffered a higher neonicotinoids contamination than the Rear river-route, resulting from more effluents of WWTPs receiving, and intensive commercial and human activities. Level of residual neonicotinoids in surface water was significantly correlated with the water quality (p < 0.01), especially items of pH, DO and ORP, and nitrogen and phosphorus contaminants. Compared with reports about residual neonicotinoids in water and sediment previously, the metropolitan regions of the Guangzhou could be confronted with a moderate contamination and showed serious ecological threats (even heavier than the Pearl Rivers). Our results will provide valuable data for understanding of neonicotinoids contamination in the Pearl River Delta and be helpful for further assessing environmental risk of neonicotinoids.

Enhanced Sensitivity and Effective Cleanup Strategy for Analysis of Neonicotinoids in Complex Dietary Samples and the Application in the Total Diet Study

Extensive residues of neonicotinoids (neonics) have been demonstrated in food and the environment by routine monitoring measurement, but little is known about the residue levels in "ready to eat" dietary samples. To obtain a more accurate picture of dietary exposure to total neonics, an ultrasensitive and effective cleanup analytical method for the quantification of neonics in dietary samples was established on the basis of cold-induced phase separation and pre-column dilution injection liquid chromatography-high-resolution mass spectrometry. A total of 10 neonics were quantified in ultratrace amounts (ng/kg) using stable isotope dilution, with calibration curves spanning 4 orders of magnitude. Satisfactory accuracy (73.5-109.2% for the recoveries) and precision (0.6-13.2% for the relative standard deviation ranges) were obtained in method validation. Moreover, tolerable absolute matrix effects (0.89-1.09) were also obtained in 12 kinds of dietary matrices with weak relative matrix effects (2.8-12.6%). The validated method was applied to the dietary samples collected from the Chinese Total Diet Study, and the results showed that 75% of the samples were contaminated with at least one neonicotinoid.

Developmental Toxicity of a Neonicotinoid Insecticide, Acetamiprid to Zebrafish Embryos

Agricultural use of neonicotinoid insecticides is increasing worldwide, posing a risk to nontarget organisms. The present study investigated developmental toxicity of a widely used neonicotinoid, acetamiprid, to zebrafish embryos. Sublethal (malformations, hatchability, heart rate, body length, alteration of spontaneous movement and touch responses) and lethal effects were monitored during exposure period from 6 h post fertilization (hpf) to 120 hpf. Zebrafish embryos exhibited significant mortality and teratogenic effects at acetamiprid concentration greater than 263 mg/L, with bent spine being the main malformation. Toxicity spectra were constructed to rank the sensitivity of individual end points to acetamiprid exposure and impaired spontaneous movement was the most sensitive end point of those tested. The present study provides the basis for understanding developmental toxicity of acetamiprid exposure to zebrafish embryos. This information is critical for future studies evaluating aquatic risk from neonicotinoids as little is known regarding adverse effects of neonicotinoids to aquatic vertebrate species.

Occurrence and risk of neonicotinoid insecticides in surface water in a rapidly developing region: Application of polar organic chemical integrative samplers

Extensive use of neonicotinoid insecticides (NNIs) worldwide calls for further knowledge on their environmental occurrence and risk. The present study highlighted the need for more research on long-term exposure of NNIs in aquatic environment, which is important but remains elusive. Time weighted average concentrations of five commonly used NNIs in urban waterways of Guangzhou, China were measured using newly developed polar organic chemical integrative samplers (POCIS). Acetamiprid (from 18.8 ± 1.9 to 157 ± 31 ng/L; mean ± standard deviation), clothianidin (from 14.8 ± 3.7 to 47.6 ± 10.0 ng/L) and imidacloprid (from 32.9 ± 11.6 to 249 ± 19 ng/L) were detectable in all samples. Thiamethoxam was found at 71.4% of the 21 sampling sites (from not detected to 52.4 ± 9.4 ng/L), while thiacloprid was not detected at any site. Vegetable planting and sewage effluent were the main sources of NNIs in surface water in Guangzhou. Probabilistic environmental exposure distributions were subsequently constructed using the measured concentrations and the exceedances of predicted environmental concentrations of NNI to ecological thresholds were assessed. In Guangzhou, 63.5%, 16.2%, 87.8% and 17.2% of acetamiprid, clothianidin, imidacloprid and thiamethoxam, respectively, exceeded an interim chronic threshold of 35 ng/L for NNIs. Further risk assessment and control measures for the use of NNIs are advocated for protecting the integrity of aquatic ecosystems.

Application of Box-Behnken design and desirability function in the optimization of Cd(II) removal from aqueous solution using poly(o-phenylenediamine)/hydrous zirconium oxide composite: equilibrium modeling, kinetic and thermodynamic studies

In this research work, poly(o-phenylenediamine) was incorporated into the hydrous zirconium oxide matrix to form poly(o-phenylenediamine)/hydrous zirconium oxide composite which is used for the removal of Cd(II) from aqueous solution. The characterization of the material was done based on FTIR, XRD, SEM, and TGA-DTA. The effects of contact time, pH, adsorbent dose, and initial concentration of Cd(II) on the removal of Cd(II) were studied by performing 29 sets of sorption runs using Box-Behnken design combined with response surface methodology (RSM). Various isotherm models were tested to describe the adsorption equilibrium. The adsorption equilibrium data fitted well with Freundlich isotherm model. The maximum adsorption capacity of 66.66 mg g^-1 was obtained from Langmuir isotherm. The pseudo-second-order kinetic model described the adsorption kinetics more accurately. Diffusion-based kinetics such as intraparticle diffusion and Bangham's model suggested that both film and intraparticle pore diffusion were involved in the adsorption process. The Elovich model pointed towards the chemisorption. The investigation of desorption and regeneration suggested that the material can be used as an effective sorbent for removal of Cd(II) from aqueous system.

Rational design of a molecularly imprinted polymer for dinotefuran: theoretical and experimental studies aimed at the development of an efficient adsorbent for microextraction by packed sorbent

In this work, we studied theoretically the formation process of a molecularly imprinted polymer (MIP) for dinotefuran (DNF), testing distinct functional monomers (FM) in various solvents through density functional theory calculations. The results revealed that the best conditions for MIP synthesis were established with methacrylic acid (MAA) as FM in a 1 : 4 stoichiometry and with chloroform as the solvent. This protocol showed the most favourable stabilization energies for the pre-polymerization complexes. Furthermore, the formation of the FM/template complex is enthalpy driven and the occurrence of hydrogen bonds between the DNF and MAA plays a major role in the complex stability. To confirm the theoretical results, MIP was experimentally synthesized considering the best conditions found at the molecular level and characterized by scanning electron microscopy and thermogravimetric analysis. After that, the synthesized material was efficiently employed in microextraction by packed sorbent combined with high-performance liquid chromatography in a preliminary study of the recovery of DNF from water and artificial saliva samples.

Nitrogen-doped graphene quantum dots-based fluorescence molecularly imprinted sensor for thiacloprid detection

In this paper, a test strip-based sensor was developed for thiacloprid quantitative detection based on PDA molecularly imprinted polymer (MIP) and nitrogen-doped graphene quantum dots (N-GQDs). Thiacloprid is a new type of nicotine insecticide, which can block the normal neurotransmitter delivery process in insects. In the sensing system, N-GQDs were immersed into filter paper at first. Then, dopamine (DA) with thiacloprid can be self-polymerized on test strip surface to form the uniform PDA film. After removed thiacloprid template, the established poly dopamine (PDA) MIP can selectively recognize thiacloprid. As a result, captured thiacloprid can enhance the fluorescence intensity of N-GQDs into the test strip. As a result, the fluorescence intensity of N-GQDs can be linearly related within a certain range of thiacloprid concentration. Under the optimum conditions, the proposed sensor for thiacloprid detection exhibited a linear ranging from 0.1 mg/L to 10 mg/L with a low detection limit of 0.03 mg/L. The N-GQDs based test strip-based sensor for thiaclopridis reported for the first time. The sensing system has high selectivity to thiacloprid and provides new opportunities in the pesticide detection.

Emerging Estrogenic Pollutants in the Aquatic Environment and Breast Cancer

The number and amount of man-made chemicals present in the aquatic environment has increased considerably over the past 50 years. Among these contaminants, endocrine-disrupting chemicals (EDCs) represent a significant proportion. This family of compounds interferes with normal hormonal processes through multiple molecular pathways. They represent a potential risk for human and wildlife as they are suspected to be involved in the development of diseases including, but not limited to, reprotoxicity, metabolic disorders, and cancers. More precisely, several studies have suggested that the increase of breast cancers in industrialized countries is linked to exposure to EDCs, particularly estrogen-like compounds. Estrogen receptors alpha (ERα) and beta (ERβ) are the two main transducers of estrogen action and therefore important targets for these estrogen-like endocrine disrupters. More than 70% of human breast cancers are ERα-positive and estrogen-dependent, and their development and growth are not only influenced by endogenous estrogens but also likely by environmental estrogen-like endocrine disrupters. It is, therefore, of major importance to characterize the potential estrogenic activity from contaminated surface water and identify the molecules responsible for the hormonal effects. This information will help us understand how environmental contaminants can potentially impact the development of breast cancer and allow us to fix a maximal limit to the concentration of estrogen-like compounds that should be found in the environment. The aim of this review is to provide an overview of emerging estrogen-like compounds in the environment, sum up studies demonstrating their direct or indirect interactions with ERs, and link their presence to the development of breast cancer. Finally, we emphasize the use of in vitro and in vivo methods based on the zebrafish model to identify and characterize environmental estrogens.