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The identification of residual thiram (Tr) in foods is vital in view of its harmful effects on human health. Herein, a ratiometric fluorescence sensor (I

In this work, a novel extraction technique based on the effervescence-assisted dispersion and magnetic recovery of attapulgite/polypyrrole sorbents was developed for determining the concentrations of five pyrethroids in honey samples. The magnetic nanoparticles were synthesized by a one-pot method. Several experimental parameters that affected the extraction efficiency, including the dispersion conditions, pH, ionic strength, and desorption conditions, were investigated. Under optimal conditions, the calibration curves for the five pyrethroids in honey samples exhibited good linearity, with r2 values ranging from 0.9979 to 0.9990. The limits of detection varied between 0.21 and 0.34 µg/L. Satisfactory recoveries of 81.42-106.73% with intra- and interday relative standard deviations of less than 6.94 and 10.89%, respectively, were obtained. Moreover, the sorbents exhibited acceptable batch-to-batch repeatability in the range of 5.06-15.01%, and each sorbent could be reused for up to four extraction cycles without a significant loss in the extraction recovery.

A new, simple colorimetric aptasensor based on the aggregation-induced color change of citrate-stabilized AuNPs was designed for the specific and sensitive determination of ametryn. Citrate-stabilized AuNPs with negative surface charges were synthesized via an easy one-pot reaction. Because of the electrostatic interaction between the three-nitrogen hybrid ring of ametryn and gold nanoparticles, the citrate-stabilized AuNPs easily undergo aggregation in the presence of ametryn. Thus, with a color change from wine red to gray, ametryn was visually detected by a colorimetric aptasensor. In addition, the detection result can also be measured quantitatively using a UV-vis spectrophotometer. The aptasensor has good selectivity and sensitivity to ametryn in the linear range of 0–80.0 μg L−1. According to the IUPAC criteria (3σ rule), the detection limit of ametryn is 0.15 μg L−1. Moreover, the aptasensor was successfully applied to the detection of ametryn in Yongding River from Zhaocun, Yizhuang Jingkai Sewage Treatment Plant and Yizhuang Nokia Factory water samples. The recovery reached 98.9–101.6%, 95.7–101.3% and 100.0–103.3%, respectively. The excellent performance of the colorimetric aptasensor in the detection of ametryn indicates its potential applications in the detection of ametryn in more complex environmental samples.

A turn-on fluorescent sensing platform based on an ultralow concentration of Al-metal organic frameworks for the detection of aflatoxin B

Hyperbranched polytriazine functionalized with humic acid was prepared and developed as new sorbents for dispersive solid-phase extraction of three acaricides (clofentezine, fenpyroximate, and pyridaben) in tea samples combined with high-performance liquid chromatography detection. The sorbents were characterized by scanning electron microscopy, energy dispersive spectroscopy, Zeta-potential, and Fourier transform infrared spectroscopy. The extraction parameters (extraction time, ionic strength, desorption conditions) were optimized. The adsorption mechanism was evaluated utilizing Fourier transform infrared spectra. Under optimum conditions, satisfactory analytical performances were achieved, which included high precision (1.33-9.62%), low limits of detection (0.19-3.54 µg/L), and wide linear range (2.5-500 µg/L) for the analysis of the acaricides. Moreover, the proposed method proved highly effective for the determination of acaricides in tea samples, with the relative recoveries in the range of 65.20-108.13% and relative standard deviations < 9.87%. The method has great application potential for the detection of acaricides in tea samples.

In this study, a green and effective ultrasound-assisted dispersive liquid-liquid microextraction method based on a hydrophobic deep eutectic solvent (UA-DLLME-DES) was developed for the preconcentration and determination of pyrethroid insecticides (deltamethrin, fenvalerate, permethrin, etofenprox, and bifenthrin) in environmental water samples using high-performance liquid chromatography combined with an ultraviolet detector (HPLC-UVD). Hydrophobic deep eutectic solvents (DESs) are green solvents prepared by mixing quaternary phosphonium salts and straight-chain monobasic acids. DESs were synthesized and characterized by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). Several key parameters, including the types and amounts of DESs, pH value, sample volume, ultrasound time, salt addition, and centrifugation rate and time, were researched and optimized. Under the optimal experimental conditions, the proposed method required only a small amount of DES to complete extraction and recovery in a very short time. The validated method showed good linearity, with a coefficient of determination (R2) ranging from 0.9992 to 0.9995, and good repeatability, with relative standard deviations (RSDs) ranging from 1.45 to 4.86%, for all analytes. The limits of detection (LODs) varied from 0.30 to 0.60 μg/L. Finally, the presented method was implemented to determine the pyrethroid insecticides in environmental water samples, and acceptable recoveries within the range of 80.93–109.88% were obtained.

Magnetic hyperbranched polyamideamine was carboxylated using succinic anhydride and modified further with 1-octyl-3-methylimidazole hexafluorophosphate successively. The morphology and chemical composition of the prepared material was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement, X-ray photoelectron spectroscopy, etc. 1-Octyl-3-methylimidazole hexafluorophosphate modified magnetic hyperbranched polyamideamine was used as sorbent in the magnetic solid-phase extraction for the separation and enrichment of five pyrethroid insecticides from tea infusion. The magnetic solid-phase extraction method proposed in this article has low method detection limits (0.53-0.71 ng/mL), acceptable coefficient of determination (0.9992-0.9998), wide linear ranges (2.5-500.0 ng/mL), and good repeatability (intraday: 1.2-6.3%; interday: 1.6-5.4%). In the detection of five pyrethroid insecticides in tea infusion, relative recoveries were in the range from 87.7 to 114.7% with satisfactory relative standard deviations (0.2-7.4%). With the aid of quantum chemistry calculations, the interaction energy between the sorbent and five pyrethroid insecticides was calculated, which proved the necessity of the modification of 1-octyl-3-methylimidazole hexafluorophosphate.

Herein, a novel hyperbranched aromatic polyamide-coated magnetic sorbent was prepared by in situ polymerization on the surface of amino-functionalized Fe3 O4 nanoparticles. The magnetic sorbent was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, elemental analysis, Brunauer-Emmett-Teller measurement, and X-ray photoelectron spectroscopy, etc. The new magnetic sorbent was used in the magnetic solid-phase extraction for the detection of seven benzoylurea insecticides. Under optimum conditions, low method detection limits (0.56-1.20 ng/mL), acceptable coefficient of determination (0.9967-0.9996), wide linear ranges (2.5-500.0 ng/mL), and good repeatability (intraday: 2.0-7.3%; interday: 1.9-9.2%) were achieved. The magnetic solid-phase extraction method based on the new magnetic sorbent showed good reliability in the analysis of seven benzoylurea insecticides in real water samples, as the relative recoveries were in the range from 80.1 to 116.3% with satisfactory RSDs (0.1-9.8%). By means of density functional theory and semiempirical quantum mechanical, the binding configuration and interaction energy of hyperbranched aromatic polyamide and benzoylurea insecticides were calculated. The result of theoretical calculation revealed that the adsorption of benzoylurea insecticides by hyperbranched aromatic polyamide was derived from hydrogen bonding and π-π stacking. The contribution of π-π stacking was greater than that of hydrogen bond, which was confirmed by energy decomposition analysis.

A green, simple, inexpensive, and sensitive ionic liquid immobilized fabric phase sorptive extraction method coupled with high performance liquid chromatography was developed for rapid screening and simultaneous determination of four fungicides (azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin) residues in tea infusions. This IL modified extraction fiber is capable of extracting target analytes directly from complicated tea water matrices with the addition of surfactant. A series of extraction conditions were investigated by one-factor-at-a-time approach and orthogonal test. After a series experiments, the optimum conditions were found to be 10% [HIMIM]NTf2 as coating solution, 2min vortex time, 500μL acetonitrile as dispersive solvent and 2min desorption time. Under the above conditions, the proposed technique was applied to detect fungicides from real tea water samples with satisfactory results.

We present a novel dispersive liquid-liquid microextraction method based on the solidification of deep eutectic solvent coupled with high-performance liquid chromatography with a variable-wavelength detection for the detection of five benzoylureas in real water samples. In this work, a green solvent consisting of 1-octyl-3-methylimidazolium chloride and 1-dodecanol was used as an extraction solvent, yielding the advantages of material stability, low density, and a suitable freezing point near room temperature. Parameters that significantly affect extraction efficiency were optimized by the one-factor-at-a-time approach. Under optimal conditions, the recoveries of five target compounds were obtained ranging from 87.39 to 98.05% with correlation coefficients ranging from 0.9994 to 0.9997 for pure water. The limits of detection were in the range of 0.09-0.16 μg/L. The enrichment factors were in the range of 171-188. Linearities were achieved in the range of 0.5-500 μg/L. The proposed method was successfully applied to determine benzoylureas in environmental water samples with a satisfactory recovery of approximately 81.38-97.67%.

Phytophagous mites are usually considered a difficult problem for agricultural planting, and acaricides are applied to control diseases and pests. However, the overdose and misusage of acaricides causes pesticide residues. In this work, a simple and practical ionic liquid-based TiO 2 nanofluid, effervescence-assisted, dispersive liquid–liquid microextraction (EA-DLLME) method was developed to detect acaricides in honey and tea by high-performance liquid chromatography (HPLC-DAD). Oleophilic TiO 2 nanoparticles were synthesized by a facile solvothermal method to obtain greater stability of the nanofluid. The experimental parameters were optimized by a one-factor-at-a-time approach and included the effervescent tablet composition, ionic liquid selection, extractant composition, nanofluid volume, extraction temperature, extraction time and desorption conditions. Under the optimized conditions, the linear ranges of this proposed method were 0.5–500 μg L −1 , with correlation coefficients in the range of 0.9985–1.0000. The extraction efficiencies for the target analytes varied from 70.70 to 84.58%. The detection and quantitation limits were in the ranges of 0.04–0.18 μg L −1 and 0.13–0.60 μg L −1 , respectively. The intra- and inter-day relative standard deviations ( n = 3) were found to range from 2.32 to 5.71%, which showed perfect repeatability. Overall, the EA-DLLME method was time-saving and environmentally friendly, with future potential for microextraction.

In this research, a novel method using magnetic mixed hemimicelles dispersive solid-phase extraction (MMHDSPE) based on C16mimBr-coated attapulgite/polyaniline-polypyrrole/Fe3O4 (ATP/PANI-PPY/Fe3O4) nanocomposites were investigated for enrichment and separation of three acaricides in fruit juice. In this method, we combined the simplicity and speed of dispersive solid-phase extraction, the advantages of mixed hemimicelles and the facility of the phase separation of the magnetic nanoparticles to develop a simple, rapid, sensitive, and effective method for detecting target analytes from the juice samples. ATP/PANI-PPY/Fe3O4 nanocomposites were successfully synthesized using a one-pot method. The as-prepared nanocomposite sorbents were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The experimental factors affecting the extraction efficiency including the sorbent type, amount of ATP/PANI-PPY/Fe3O4 nanocomposites, volume of ILs, sonication time, pH, and desorption conditions were optimized. Under the optimal conditions, good linearity was observed for all target analytes, with correlation coefficients (r2) ranging from 0.9994 to 0.9999; the limits of detection (LOD) were in the range of 0.16-0.57μgL-1, and the recoveries of analytes using the proposed method ranged between 88.67% and 95.10%. The sorbents exhibited excellent repeatability in the range of 1.83-4.24% in extracting the three target analytes. In addition, the intra-day and inter-day precision values were found to be in the range of 0.19-6.24% and 2.23-8.36%, respectively. The method was successfully applied to analyze fruit juice samples by rapid preconcentration of acaricides.

In this study, low-density deep eutectic solvent combined with dispersive liquid-liquid microextraction was applied to the extraction of five benzoylurea insecticides (BUs, including diflubenzuron, triflumuron, hexaflumuron, flufenoxuron, and chlorfluazuron) from beverages. Then the extracted and concentrated samples were analyzed and detected using the high-performance liquid chromatography combined with an ultraviolet detector. The DESs were synthesized by [P14,6,6,6]Cl as hydrogen bond acceptor and tetradecyl alcohol as hydrogen bond donor, and then characterized by Fourier transform infrared spectroscopy. In the experiment, the key factors affecting the extraction efficiency were screened by Plackett-Burman design and optimized with the central composite design. The extraction recovery rates were 85.91–95.12%. The limits of detection and correlation coefficients of the method were 0.30–0.60 μg L−1 and 0.9992–0.9997. Finally, the method was applied to determine the BUs in four beverage samples, and satisfactory recoveries, within the range of 76.87–101.19% were achieved. The present method has the potential to be applied to the detection of BUs in aqueous samples.

Ultraviolet (UV) irradiation is widely used for water treatment due to its effectiveness against a wide range of waterborne pathogens with minimal production of regulated disinfection byproducts. However, in this study, the formation of methyl chloride (CH

The Fe3O4@MIL-100(Fe) hybrid composites are successfully synthesized via an in-situ growth method and characterized using various techniques. The ability of the magnetic metal–organic framework to promote photo-Fenton like processes is investigated using levofloxacin as a representative substrate. The results show that the composite with a Fe3O4:MIL-100(Fe) mass ratio of 1:4 has a higher degradation efficiency (up to 93.4%) than Fe3O4, MIL-100(Fe), and the other fabricated composites. This higher catalytic activity is ascribed to the synergistic effect between Fe3O4 and MIL-100(Fe), by which the quick separation of hole-electron pair from MIL-100(Fe) and the efficient reduction of Fe3+ to Fe2+ in the photo-Fenton reaction are mutually promoted. Moreover, the composite shows favorable recyclability without apparent loss of apparent photo-Fenton activity even after five cycles, and more importantly, can be recovered magnetically. The possible degradation mechanism and intermediates of levofloxacin in the photo-Fenton reaction have been tentatively proposed based on free radical quenching, electron paramagnetic resonance and mass spectrometry analysis. Finally, the developed Fe3O4@MIL-100(Fe) is successfully applied for the removal of levofloxacin from spiked wastewater with removal efficiencies ranging from 77.9 to 85.5%, which indicates that the proposed system has significant potential for wastewater treatment applications.

A magnetic Metal-Organic Frameworks composite material modified with attapulgite was prepared via in situ growth method and characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, N2 adsorption-desorption and vibration sample magnetometer analysis. It was applied as an efficient adsorbent for the magnetic solid-phase extraction of seven benzoylurea insecticides from environmental water samples couple with high-performance liquid chromatography detection. Under the optimized experimental conditions, the established procedure exhibited low limit of detection ranging from 0.75 to 1.5 µg L−1 and good linear response ranging from 2.5 to 500 µg L−1 with coefficients of determination >0.99. The method recoveries of spiked analytes at the concentrations of 20, 100 and 200 µg L−1 in real water samples were 73.56–99.63% with the relative standard deviations

A pretreatment method using in-syringe dispersive liquid–liquid microextraction based on the direct solidification of ionic liquids before high performance liquid chromatography analysis was developed for the determination of benzoylurea insecticides (BUs) in honey samples. The hydrophobic ionic liquid [N4444][PF6], formed in situ by the hydrophilic ionic liquid [N4444]Cl and the ion exchange reagent KPF6, was used to extract the target analytes. The entire extraction procedure was performed in a syringe. The extractant was solidified at room temperature and collected using a nylon membrane filter. This technique did not require a dispersive solvent, vortex mixer, ultrasound bath, or centrifugation. The parameters affecting the extraction efficiency were investigated through an experimental design. Under the optimal conditions, the limits of detection for the four BUs varied from 0.21 to 0.42 μg L−1 in solution (2.1–4.2 μg kg−1 in honey). Good linearities were obtained in the range of 2–300 μg L−1, with coefficients of determination greater than 0.999. The recoveries of the four BUs ranged from 80.94% to 84.59%. The intra-day (n = 3) and inter-day (n = 3) relative standard deviations were less than 5.08%. Finally, the proposed method was applied to the determination of BUs in commercial honey samples with satisfactory results.

In this study, a simple effervescence-assisted dispersive solid-phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic-liquid-modified magnetic β-cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one-factor-at-a-time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3–5.44%. The detection and quantitation limits were in the ranges of 0.07–0.38 and 0.23–1.27 μg·L−1, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost-effective, environmentally friendly, and time-saving. This article is protected by copyright. All rights reserved

Fe 3 O 4 @nSiO 2 @mSiO 2 was prepared successfully and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), infrared spectrometer (FT-IR), BET surface area measurements and Zeta potential analysis techniques. The contact time, initial concentration of congo red, temperature and pH on adsorption capacity were studied. The adsorbent shows highly efficient adsorption properties, with maximum adsorption capacity of 1428 mg g − 1 for congo red, which is much higher than the other adsorbents (normally below 300 mg g − 1 ). The adsorption kinetics and isotherm of congo red on Fe 3 O 4 @nSiO 2 @mSiO 2 were systematically investigated and found that the adsorption kinetics and isotherm were well fitted by pseudo-second-order kinetic and Langmuir isotherm model.

The appropriate projection of axons within the nervous system is a crucial component of the establishment of neural circuitry. Draxin is a repulsive axon guidance protein. Draxin has important functions in the guidance of three commissures in the central nervous system and in the migration of neural crest cells and dI3 interneurons in the chick spinal cord. Here, we report that the distribution of the draxin protein and the location of 23C10-positive areas have a strong temporal and spatial correlation. The overexpression of draxin, especially transmembrane draxin, caused 23C10-positive axon bundles to misproject in the dorsal hindbrain. In addition, the overexpression of transmembrane draxin caused abnormal formation of the ganglion crest of the IX and X cranial nerves, misprojection of some anti-human natural killer-1 (HNK-1)-stained structures in the dorsal roof of the hindbrain, and a simultaneous reduction in the efferent nerves of some motoneuron axons inside the hindbrain. Our data reveal that draxin might be involved in the fascicular projection of cranial nerves in the hindbrain.

In this work, a novel effervescence-assisted microextraction technique was proposed for the detection of four fungicides. This method combines ionic liquid-based dispersive liquid-liquid microextraction with the magnetic retrieval of the extractant. A magnetic effervescent tablet composed of Fe3O4 magnetic nanoparticles, sodium carbonate, sodium dihydrogen phosphate and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonimide) was used for extractant dispersion and retrieval. The main factors affecting the extraction efficiency were screened by a Plackett-Burman design and optimized by a central composite design. Under the optimum conditions, good linearity was obtained for all analytes in pure water model and real water samples. Just for the pure water, the recoveries were between 84.6% and 112.8%, the limits of detection were between 0.02 and 0.10 μg L(-1) and the intra-day precision and inter-day precision both are lower than 4.9%. This optimized method was successfully applied in the analysis of four fungicides (azoxystrobin, triazolone, cyprodinil, trifloxystrobin) in environmental water samples and the recoveries ranged between 70.7% and 105%. The procedure promising to be a time-saving, environmentally friendly, and efficient field sampling technique.

A novel in situ metathesis reaction combined with an ultrasound-assisted dispersive liquid–liquid microextraction based on the solidification of sedimentary ionic liquids (in situ UA-SSIL-DLLME) was combined with high-performance liquid chromatography (HPLC) to detect four triazole pesticides in water and juice samples. In this method, the hydrophobic ionic liquid [P4448][PF6], formed in situ by the hydrophilic ionic liquid [P4448]Br and the anion-exchange reagent KPF6, was used as the microextraction solvent. The extraction procedure was assisted by ultrasound at 50 W for 5 min. After centrifugation and cooling, [P4448][PF6] was sedimented at the bottom and easily collected by decanting the aqueous phase directly. Various parameters affecting the extraction efficiency, such as the quantity of [P4448]Br, the molar ratio of [P4448]Br to KPF6, salt addition, ultrasound time, centrifugation rate and time, and sample pH, were evaluated. Good linearities with correlation coefficients greater than 0.99 were obtained under the optimum conditions. The limits of detection varied between 0.90 and 1.38 μg L−1, and the enrichment factors were in the range of 94–101. The recoveries of these four triazole pesticides ranged from 85.18% to 91.14%, with relative standard deviations less than 4.86% and 5.87% for intra-day (n = 3) and inter-day (n = 3), respectively. The proposed method was then successfully applied to analyze the target compounds in environmental water and juice samples.

A new microextraction technique named in-syringe low-density ionic liquid dispersive liquid–liquid microextraction (LDIL-DLLME) followed by separation using high performance liquid chromatography has been developed to determine the levels of four pyrethroid insecticides (i.e., deltamethrin, fenvalerate, permethrin, and bifenthrin) in environmental water samples. In the developed method, an ionic liquid (IL) was used for the first time instead of an organic solvent, which is most often used in low-density solvent-based microextraction methods. The IL was placed in a long syringe needle using a microsyringe. It was then dispersed by drawing the sample solution into the syringe. The extraction was finished in the syringe, taking full advantage of the low-density property, and making this method easier and quicker. Several parameters affecting the experimental efficiency of LDIL-DLLME, such as the needle's inner diameter, salt addition, the volume of IL and sample, rotation speed and duration of centrifugation and ultrasound were thoroughly studied. Under optimized conditions, in the range of 1 to 500 μg L−1, good linearity was obtained, with coefficients of determination greater than 0.9994. Three spiked water samples were studied, and recovery ranged from 88.0 to 102.8%, with relative standard deviations (RSDs) ranging from 0.3 to 6.7%. The limits of detection (LODs) for the four pyrethroid insecticides were in the range of 0.88–1.71 μg L−1 and enrichment factors (EFs) were in the range of 242 to 257. The proposed method provides an inexpensive, rapid, simple and eco-friendly process for evaluating pyrethroid insecticides in environmental samples, making it a potential method for the pretreatment of experimental samples.

A novel and simple method for effervescence-assisted dispersive liquid–liquid microextraction based on the solidification of a floating ionic liquid using a special collection method combined with high-performance liquid chromatography is developed for the determination of four benzoylureas in water samples. In this method, the ionic liquid (IL), trihexyl(tetradecyl)phosphonium tetrafluoroborate, is used rather than organic drops, which have limitations, as the extraction solvent for the first time in dispersive liquid–liquid microextraction based on the solidification of floating organic drops (DLLME-SFO). Due to the high viscosity of the IL, it can be quickly collected in the lid of the centrifuge tube after solidification, which combines the advantages of both dispersive liquid–liquid microextraction and liquid phase microextraction based on the solidification of a floating IL. Furthermore, effervescence is used to disperse the IL, thereby avoiding the use of an organic dispersant. The influence of various experimental factors, such as the form of the effervescent material, IL quantity, base to acid ratio in the effervescent tablet, weight ratio of IL to effervescent tablet, ultrasonication time, centrifugation time, extraction temperature, sample pH, extraction time and salt addition, are optimized using a central composite design and the one-factor-at-a-time approach. Under the optimal conditions, good linearity was obtained for the four BUs from 2 to 500 μg L−1, with correlation coefficients ranging from 0.9994 to 0.9995. The recoveries were 90.2–100.2% with relative standard deviations ranging from 1.3–4.4%. The limits of detection for the analytes were between 0.77 to 1.58 μg L−1, and the enrichment factors ranged from 206 to 228. Additionally, this method was successfully applied for the determination of four BUs in real water samples.

A novel dispersive liquid–liquid microextraction (DLLME) method is proposed for the detection of five acaricides (clofentezine, fenpyroximate, diafenthiuron, pyridaben and spirodiclofen) in tea infusions prior to analysis by high-performance liquid chromatography (HPLC). For this method, a nanofluid prepared by dispersing magnetic zinc oxide nanoflower (FeO4@ZnO) nanoparticles in 1-octyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonimide) was used as an extractant. After extraction, the nanofluid was magnetically collected by the addition of FeO4@ZnO nanoparticles without centrifugation. In DLLME, the joint use of an ionic liquid (IL)-based nanofluid and magnetic retrieval is unprecedented and makes this microextraction process rapid and effective. The main parameters affecting the extraction efficiency were optimized by an orthogonal experiment and a single-factor experiment using tea infusions. Under the optimal conditions, the recoveries of the analytes were between 83.0 and 104.4%, the limits of detection ranged from 0.44 to 1.0 μg L−1, and the intra-day precision and inter-day precision were both lower than 7.5%. The proposed method was successfully applied to the analysis of acaricides in four tea infusions, and the recoveries were between 79.2 and 93.1%, with RSDs of 0.4 to 5.8%. The developed method is promising as an environmentally friendly, convenient, and efficient sample preparation technique.

A novel liquid phase microextraction method based on the solidification of floated ionic liquids (SFIL-LPME) was developed to determine four phthalate esters (diethyl phthalate, diallyl phthalate, benzyl butyl phthalate, and dicyclohexyl phthalate) in environmental waters and bottle beverages and subsequently separate them using high-performance liquid chromatography. In this work, we customized a tributyldodecylphosphonium tetrafluoroborate ([P4 4 4 12][BF4]) ionic liquid (IL) to obtain a low density such that it can be solidified at a low temperature, and then used as an extraction solvent in liquid-phase microextraction based on the solidification of floated organic drops (SFO-LPME). This means that more potential ILs can be customized to broaden extraction solvents in SFO-LPME. To identify the significant factors that affect extraction efficiency, parameters such as the volume of [P4 4 4 12][BF4], the extraction time, the rotation speed, the extraction temperature and the ionic strength were optimized using a Plackett–Burman design. A central composite design was then used to optimize the identified significant factors to study the effect of interactions on the experiment. Under these optimized conditions, the extraction recoveries of the four phthalate esters in water samples ranged from 73.0 to 94.6% and in bottled beverage were from 70.2 to 101.3%, with relative standard deviations (RSDs) ranging from 0.6 to 8.2% and 0.6 to 7.8%. Good linearity for both water samples and bottled beverages were obtained in the range of 5–500 μg L−1, with correlation coefficients greater than 0.9993. The limits of detection for the four phthalate esters varied from 0.27 to 1.1 μg L−1 for water samples and 1.22 to 2.36 μg L−1 for bottled beverages. The two developed methods were then successfully applied to the determination of phthalate esters in environmental waters and bottled beverages.

A β-cyclodextrin-modified attapulgite composite was prepared and used as a dispersive micro-solid-phase extraction sorbent for the determination of benzoylurea insecticides in honey samples. Parameters that may influence the extraction efficiency, such as the type and volume of the eluent, the amount of the sorbent, the extraction time and the ionic strength were investigated and optimized using batch and column procedures. Under optimized conditions, good linearity was obtained for all of the tested compounds, with R(2) values of at least 0.9834. The limits of detection were determined in the range of 0.2-1.0 μg/L. The recoveries of the four benzoylurea insecticides in vitex honey and acacia honey increased from 15.2 to 81.4% and from 14.2 to 82.0%, respectively. Although the β-cyclodextrin-modified attapulgite composite did not show a brilliant adsorption capacity for the selected benzoylurea insecticides, it exhibited a higher adsorption capacity toward relatively hydrophobic compounds, such as chlorfluazuron and hexaflumuron (recoveries in vitex honey samples ranged from 70.0 to 81.4% with a precision of 1.0-3.7%). It seemed that the logPow of the benzoylurea insecticides is related to their recoveries. The results confirmed the possibility of using cyclodextrin-modified palygorskite in the determination of relatively hydrophobic trace pharmaceutical residues.

A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid-liquid microextraction based on the solidification of floating organic droplets was coupled with high-performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1-dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett-Burman design and one-factor-at-a-time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5-500 μg/L, for hexaflumuron in a range of 1-500 μg/L, and for triflumuron in a range of 5-500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4-110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%.

It is necessary to establish a rapid, simple and environmentally friendly detection method for benzoylurea pesticides (BUs) in environmental water samples because of their toxicity in environmental circulation. Herein, a novel polyethylene glycol (PEG) modified magnetic covalent organic framework material based on the Schiff base reaction was prepared (PEG/Fe3O4@SNW-1). This material was used as a sorbent for enriching five BUs by magnetic solid phase extraction prior to detection via high-performance liquid chromatography. After the optimization of several parameters (such as the salinity, extraction time, amount of sorbent, desorption time, etc.) that influenced the recovery of the magnetic solid phase extraction process, the limits of detection (S/N = 3) were defined as less than 1.0 μg L−1, and the limits of quantitation (S/N = 10) were calculated as being lower than 3.4 μg L−1. A satisfactory linear range of 5–1000 μg L−1 was achieved. Finally, the proposed method was applied to analyze benzoylurea pesticides in three environmental water samples. These results indicated that the proposed method was feasible and demonstrated the potential application of the PEG/Fe3O4@SNW-1 material for detecting similar pesticide residues in environmental water samples.

A facile synthetic method of attapulgite@covalent organic frameworks was reported in this study. The composite was synthesized by covalently grafting covalent organic frameworks (synthesized from 1,3,5-triformylphloroglucinol and p-phenylenediamine) onto attapulgite at room temperature and was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, zeta potential analysis, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurement. The synthesized nanocomposite was used as a sorbent in dispersive solid phase extraction to extract pyrethroids from environmental water samples, and the parameters affecting the extraction efficiency were optimized. The linear range of the four pyrethroids was 2.5–500 μg L−1, and the enrichment factors ranged from 65.0 to 68.2. The method detection limits were between 0.83 and 1.79 μg L−1 under the optimal conditions. In addition, the intra-day and inter-day precision were 1.4%–4.8% and 2.7%–3.6%, respectively. Finally, the method was successfully applied to extract pyrethroids from real water samples with relative recoveries ranging from 71.2% to 88.7%.

Ultraviolet (UV) irradiation is widely used for water treatment due to its effectiveness against a wide range of waterborne pathogens with minimal production of regulated disinfection byproducts. However, in this study, the formation of methyl chloride (CH3Cl) from guaiacol and chloride was observed during UV254 irradiation. The results indicated that direct photolysis of guaiacol produced an arenium ion, and the reactive methoxy group was further transformed to CH3Cl in the presence of chloride. O-quinone was detected as the primary product of the degradation of guaiacol resulting from UV254 irradiation. Other organic compounds containing methoxy, ethoxy, or methylamino groups with structures that are similar to guaiacol were also demonstrated to generate halocarbons in aqueous chloride or bromide solution under UV254 irradiation. Scavenging experiments and removal of oxygen demonstrated that neither oxygen nor chlorine radicals were involved in CH3Cl formation. In seawater samples, CH3Cl was also detected in the presence or absence of added organic matter. These results demonstrate that CH3Cl can be formed during UV254 irradiation in saline water and that attention should be paid to this compound and structurally-related compounds in the application of UV254 processes.

In this study, four triazine herbicides—namely, simazine, ametryn, prometryn and terbuthylazine—were separated and determined using high-performance liquid chromatography coupled with ultraviolet detector (HPLC-UVD). The deep eutectic solvent (DES) formed by tetrabutylammonium chloride ([N4444]Cl, TBA) and ethylene glycol (EG) was selected as the extraction solvent of vortex-assisted reversed-phase liquid-liquid microextraction (VA-RPLLME). The application of the hydrophilic DES expands the range of choice for LLME. The experimental parameters affecting the extraction recoveries, including the amount of the DES, the sample volume and the vortex time, were investigated and optimized by the design of experiments (DoE) methodology. A quadratic model, namely central composite face-centered (CCF) design featuring 20 runs was used instead of the conventional trial and error approach. Under optimum conditions, the limits of determination (LODs) of the method were 0.60–1.50 μg L−1. The enrichment factors for the analytes ranged from 27 to 31. The extraction recoveries were in the range of 84.1–104.9%, and the intra-day, inter-day and intermediate relative standard deviations (RSDs) were less than 8.4%. Finally, the method was applied for the determination of triazine herbicides in vegetable oil samples. The obtained recoveries were in the range of 60.1–107.2% and RSDs were lower than 8.1%. In general, VA-RPLLME can be complementary to the present available methods for the determination of triazine herbicides in vegetable oil samples.

In this study, a novel ionic liquid-type surfactant modified attapulgite named as 1-dodecyl-3-methylimidazolium bromide-attapulgite (C12MIM-ATP) is successfully prepared and applied in dispersive solid phase extraction (dSPE) for the fast determination of pyrethroid residues in tea drinks. The primary factors that influenced the extraction efficiency, including sorbent type, amount of sorbent, extraction time, desorption conditions, pH and ionic strength, are investigated. The optimized results reveal that the extraction and desorption equilibria are rapidly obtained within 1 min. Under the optimized conditions, good linearity (2–500 μg/L) is observed for four pyrethroids in tea drinks with determination coefficients (r2) ranged from 0.9992 to 1.0000. The limits of detection (LODs) are 0.6 μg/L for all pesticides. Acceptable extraction recoveries of target analytes are found from 90.28 to 107.56% with relative standard deviations (RSDs) less than 8.30% in real tea drink samples. The batch-to-bath repeatability is evaluated by recovery test on five independent synthesized C12MIM-ATP sorbents. Satisfactory batch-to-batch repeatability is obtained with the recovery factors varied in 15%. A small matrix effect is observed using C12MIM-ATP as the sorbent for detection pyrethroids in tea drinks.

A graphene-modified, magnetic polypyrrole nanocomposite (Fe 3 O 4 @PPy/RGO) was fabricated through a facile chemical route and its application as an adsorbent for the removal of a dye was also demonstrated. The as-prepared Fe 3 O 4 @PPy/RGO nanocomposite was characterized by Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), N 2 adsorption–desorption, and zeta potential analysis techniques. The Fe 3 O 4 @PPy/RGO nanocomposite showed excellent water dispersibility because of the hydrophilicity of Fe 3 O 4 and RGO. Adsorption experiments indicated that Fe 3 O 4 @PPy/RGO adsorbs methylene blue fast and efficiently, with an adsorption capacity of up to 270.3 mg g −1 . The kinetic adsorption data fit the pseudo-second-order model and the isotherm data followed the Langmuir model. Additionally, adsorption of MB on Fe 3 O 4 @PPy/RGO also can utilize the electrostatic interaction and π–π interaction between Fe 3 O 4 @PPy/RGO and MB. Moreover, compared to other nanoparticle adsorbents, the as-prepared Fe 3 O 4 @PPy/RGO is highly flexible and easy to operate and retrieve. Most importantly, it is easy to disperse, which enables its potential application in wastewater treatment.

A novel and simple ionic-liquid-mingled air-assisted liquid–liquid microextraction based on solidification of floating organic droplets combined with high performance liquid chromatography was developed for the determination of six benzoylureas (BUs) in water and honey samples. In this method, a mixture of low-density and low melting point extraction solvents and aqueous sample solutions was rapidly sucked up and injected several times using a glass syringe. The influence of the main factors on the efficiency of this procedure is studied. Under the optimal conditions, the enrichment factors (EFs) for BUs were acquired in the range of 144 to 187, limits of detection (LODs) were between 0.01 and 0.1 μg L−1 and limits of quantitation (LOQs) were changed in the range of 0.03 and 0.33 μg L−1. The obtained extraction recoveries ranged from 84.03% to 109.20% with intra-day lower than 4.5%, and inter-day precision lower than 6.5%. The method is successfully applied to determine the BUs in environmental water and honey samples with recoveries in the range of 78.57–109.72%, which proved the potential use of this method in real samples.

An ultrasound-assisted, hybrid ionic liquid, dispersive liquid-liquid microextraction method coupled to high-performance liquid chromatography with a variable-wavelength detector was developed to detect ten insecticides, including diflubenzuron, triflumuron, hexaflumuron, flufenoxuron, lufenuron, diafenthiuron, transfluthrin, fenpropathrin, γ-cyhalothrin and deltamethrin, in fruit juices. In this method, an appropriate extraction solvent was chosen based on the partition coefficient of the target compounds. A mixture of 1-octyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide was used as the extractant. The extraction efficiency was screened using Plackett-Burman design and optimized using central composite design. Under the optimal conditions, good linearity was obtained for all the analytes in the pure water model and the fruit juice samples. In pure water, the recoveries of the ten insecticides ranged from 85.7 to 108.9%, with relative standard deviations for one day ranging from 1.24 to 2.64%. The limits of detection were in the range of 0.19-0.69 μg/L, and the enrichment factors were in the range of 123-160. The logarithm of the n-octanol/water partition coefficient in this experiment is a useful reference to select a suitable extraction solvent, and the proposed technique was applied for the analysis of ten insecticides in fruit juice with satisfactory results.

In the present study, a simple and rapid sample preparation method designated ultrasound-assisted dispersive liquid-liquid microextraction based on a deep eutectic solvent (DES) followed by high-performance liquid chromatography with ultraviolet (UV) detection (HPLC-UVD) was developed for the extraction and determination of UV filters from water samples. The model analytes were 2,4-dihydroxybenzophenone (BP-1), benzophenone (BP) and 2-hydroxy-4-methoxybenzophenone (BP-3). The hydrophobic DES was prepared by mixing trioctylmethylammonium chloride (TAC) and decanoic acid (DecA). Various influencing factors (selection of the extractant, amount of DES, ultrasound duration, salt addition, sample volume, sample pH, centrifuge rate and duration) on UV filter recovery were systematically investigated. Under optimal conditions, the proposed method provided good recoveries in the range of 90.2-103.5% and relative standard deviations (inter-day and intra-day precision, n=5) below 5.9%. The enrichment factors for the analytes ranged from 67 to 76. The limits of detection varied from 0.15 to 0.30ngmL-1, depending on the analytes. The linearities were between 0.5 and 500ngmL-1 for BP-1 and BP and between 1 and 500ngmL-1 for BP-3, with coefficients of determination greater than 0.99. Finally, the proposed method was applied to the determination of UV filters in swimming pool and river water samples, and acceptable relative recoveries ranging from 82.1 to 106.5% were obtained.

A novel dispersive magnetic solid phase microextraction method based on ionic liquid-coated and cyclodextrin-functionalized magnetic core dendrimer nanocomposites has been developed for the determination of pyrethroids in juice samples. The different generation magnetic core dendrimer nanocomposites were successfully synthesized and the nanocomposites possess both the selective retention of guest dendrimer and cyclodextrin molecules and high adsorption capacities of ionic liquids. The extraction efficiencies of different generation magnetic core dendrimer nanocomposites were compared, and the type of nanocomposite with the highest recovery was obtained. Under the optimized experimental conditions, the method showed good linearity in the range of 3.5–500 μg L−1. The LODs and LOQs were in the ranges of 0.36–1.3 μg L−1 and 1.2–4.3 μg L−1, respectively. The method also showed acceptable accuracies ranging from 98.2% to 99.4%. The proposed method was demonstrated to broaden the potential applications of dendrimer for the detection of pyrethroid residues in various juice samples.

A directly suspended-solidified floating organic droplet microextraction (DS-SFO) method was developed for the preconcentration of four fungicides (i.e., chlorothalonil, triadimefon, cyprodinil, and trifloxystrobin) from water and honey samples prior to HPLC-DAD detection. In this technique, no special devices or supporting materials are required. The extraction phase can be easily collected via solidification of the microdroplet after the desired extraction time. The experimental parameters affecting the extraction efficiency were investigated and optimized, which resulted under optimal conditions of a 20 μL microdroplet of 1-dodecanol as the organic extractant, 3 mL of water or diluted honey sample without salt addition, and 90 min of stirring at 900 rpm and 30 °C. Under the optimized conditions, the proposed method achieved high extraction recoveries of 80% to 93% and 70% to 83% for water and honey samples, respectively. The limits of detection (LOD) of the method were in the range of 0.20–1.95 ng mL−1 for water samples and 1.14–11.06 ng g−1 for honey samples. The relative standard deviation (RSD) was 0.9980) over the calibration range of 5–1000 ng mL−1 were obtained. This method allowed the use of green solvents, a minimal usage of organic solvents, simple device and extraction processes, and high-throughput operations. Finally, the proposed method was successfully applied to the determination of fungicides in real water and honey samples.

A method was developed using dispersive solid-phase extraction based on hyperbranched polymer functionalized with β-cyclodextrin for extraction and enrichment of three pyrethroid pesticides (fenpropathrin, cyhalothrin, and ethofenprox) in environmental water samples before high-performance liquid chromatography analysis. The aim of this research was to establish a simple, high-speed, effective, and sensitive method for the detection of target analytes. The as-prepared sorbents were synthesized successfully, and characterized by scanning electron microscopy, energy dispersive spectroscopy, elemental analysis, Brunauer-Emmett-Teller measurement and Fourier transform infrared spectroscopy. The experimental factors influencing the extraction efficiency such as extraction time, pH, ionic strength, desorption conditions, etc. were optimized. Good linearity was observed for all three pyrethroids, and the linear range of fenpropathrin was 10–500 ng/mL, and cyhalothrin, ethofenprox were 5–500 ng/mL. The method detection limits were ranged from 1.0 ng/mL to 2.1 ng/mL under the optimal conditions. The recoveries achieved ranged from 83.1% to 91.6% for the extraction of the three target analytes. Apart from these, the relative standard deviation (intra-day and inter-day) were measured fewer than 6.0%. The method in this work was applied to the rapid enrichment and detection of pyrethroids in environmental water samples.

Ni–La(OH) 3 nanotube arrays have been fabricated in a large scale via a simple electrochemical method without any hard templates and surfactants. The structure and morphology of the as-prepared Ni–La(OH) 3 nanotube were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). The FE-SEM and (HR)TEM images indicate that the obtained samples are relatively straight and regular with diameters of 150 nm. The maximum adsorption capacity of the as-prepared products for Congo red is about 96 mg g −1 , suggesting its promising application in removing organic dye from wastewater. Meanwhile, this approach can provide a convenient route to synthesize other nanoarrays.

A novel water-based slow injection ultrasound-assisted emulsification microextraction (SI-USAEME) method followed by ultra-high performance liquid chromatography-tandem mass spectrometry analysis was developed for the rapid pretreatment and determination of deoxynivalenol (DON) and its metabolite, de-epoxy-deoxynivalenol (DOM-1), in maize and pork samples. After optimization, the method recoveries for DON and DOM-1 ranged from 73 to 85 % with intraday and interday variations less than 9.4 and 9.2 %, respectively. The limits of detection for DON were 4.2 μg kg(-1) in maize and 6.2 and 5.9 μg kg(-1) for DON and DOM-1, respectively, in pork. In addition, an immunoaffinity column (IAC) was prepared. A study comparing the IAC cleanup method, the solid-phase extraction (SPE) cleanup method, and the proposed SI-USAEME method was presented. The water-based SI-USAEME method could become a simple, low-cost alternative to the conventional IAC and SPE method. The method was successfully applied to the analysis of commercial maize and pork products.

In this research, a novel method using magnetic mixed hemimicelles dispersive solid-phase extraction (MMHDSPE) based on C