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Biosensors & Bioelectronics May 2016A novel approach to synthesize molecularly imprinted polymer (MIP) nanoparticles using a MIL-101 support (a type of metal-organic framework) is reported herein for the...
A novel approach to synthesize molecularly imprinted polymer (MIP) nanoparticles using a MIL-101 support (a type of metal-organic framework) is reported herein for the first time; the sample is referred as MIL@MIP. The nanoparticles were well distributed within the polymer film, and exhibit an octahedral shape, satisfied thermal stability, and a high specific surface area (SSA) of 1579.43 m(2)g(-1). The adsorption behavior of MIL@MIP toward metolcarb in aqueous solution was subsequently examined. The synthesized MIL@MIP displayed satisfactory high transfer mass rates and a high selective adsorption affinity for metolcarb. Based on these results, a quartz crystal microbalance (QCM) sensor based on MIL@MIP was subsequently constructed and examined for the sensitive detection of metolcarb. Under optimal conditions, the detection limit of the system assessed in pear juice was 0.0689 mg L(-1) within a linear concentration range of 0.1-0.9 mg L(-1). MIL@MIP-QCM system combines the advantages of MIL-101 and molecularly imprinted technology (MIT), thereby achieving high detection sensitivity and selectivity. The current findings suggest the potential of MIL@MIP for detecting trace level pesticides and veterinary drugs for food safety and environmental control.
Topics: Adsorption; Biosensing Techniques; Coordination Complexes; Limit of Detection; Metal-Organic Frameworks; Metals; Molecular Imprinting; Nanoparticles; Pesticides; Phenylcarbamates; Polymers; Quartz Crystal Microbalance Techniques
PubMed: 26735869
DOI: 10.1016/j.bios.2015.12.071 -
Organic Letters Jun 2015A new naphthol-appended calix[4]arene (NOC4) has been synthesized and characterized. NOC4 is clicked onto a microstructured Au surface and exhibits selective macroscopic...
A new naphthol-appended calix[4]arene (NOC4) has been synthesized and characterized. NOC4 is clicked onto a microstructured Au surface and exhibits selective macroscopic recognition of metolcarb (MC) via contact angle measurements. The proposed wettability sensing device displays remarkable specificity and is fast and easy to use, which should be suitable for the rapid detection of MC in environmental monitoring.
Topics: Calixarenes; Molecular Structure; Naphthols; Pesticides; Phenols
PubMed: 26046818
DOI: 10.1021/acs.orglett.5b01075 -
Talanta Aug 2015Graphene-based magnetic nanoparticles, comprising zero-valent iron, iron oxide-oxyhydroxide and graphene, were prepared through a simple one-step synthesis method, and...
Graphene-based magnetic nanoparticles, comprising zero-valent iron, iron oxide-oxyhydroxide and graphene, were prepared through a simple one-step synthesis method, and subsequently applied to magnetic solid-phase extraction for the determination of trace carbamate pesticides in tomatoes coupled with high performance liquid chromatography. The properties of the nanocomposites were confirmed by using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer. The components within the nanocomposites endowed the material with high extraction performance and manipulative convenience. Compared with reduced graphene oxide, the as-prepared G-MNPs showed the better extraction efficiencies for the carbamate pesticides thanks to the contribution of the iron-containing magnetic nanoparticles to the adsorption capacity of the nanocomposites. Various experimental parameters affecting the extraction efficiency had been investigated in detail. Under the optimal conditions, the method provided high enrichment factors ranging from 364 to 434, good linearities ranging from 5 to 200ng g(-1) for metolcarb, baygon and methiocarb and 10 to 200ng g(-1) for carbofuran and isoprocarb, low limits of detection ranging from 0.58 to 2.06ng g(-1), and satisfactory spiked recoveries (between 90.34% and 101.98% with the relative standard deviation values from 1.21% to 5.93%). It was confirmed that this novel method was an efficient pretreatment and enrichment procedure and could be successfully applied for extraction and determination of trace carbamate pesticides in complex matrices.
Topics: Chromatography, High Pressure Liquid; Ferric Compounds; Food Analysis; Food Contamination; Graphite; Hydrogen-Ion Concentration; Iron; Limit of Detection; Solanum lycopersicum; Magnetics; Magnetite Nanoparticles; Osmolar Concentration; Pesticides; Reproducibility of Results; Solid Phase Extraction; Time Factors
PubMed: 25966405
DOI: 10.1016/j.talanta.2015.04.018 -
Analytica Chimica Acta Apr 2015Graphene is a good adsorbent for organic pollutants, especially for compounds containing benzene rings. When used in TiO2 nanotube arrays for micro-solid phase...
Graphene is a good adsorbent for organic pollutants, especially for compounds containing benzene rings. When used in TiO2 nanotube arrays for micro-solid phase extraction (μ-SPE), the combination of graphene's strong adsorptive properties with its good separation capabilities results in excellent sample preconcentration performance. In the present study, graphene-modified TiO2 nanotube arrays were prepared by electrodeposition using a cyclic voltammetric reduction method. Four carbamate pesticides, including metolcarb, carbaryl, isoprocarb, and diethofencarb, were used as model analytes to validate the enrichment properties of the prepared adsorbent in μ-SPE. Factors affecting the enrichment efficiency of the μ-SPE procedure were optimized and included sample pH, elution solvents, salting-out effect, adsorption time and desorption time. Under optimal conditions, graphene-modified TiO2 nanotube arrays exhibited excellent enrichment efficiency for carbamate pesticides. The detection limits of these carbamate pesticides ranged from 2.27 to 3.26 μg L(-1). The proposed method was validated using four environmental water samples, and yields of pesticides recovered from spiked test samples of the four analytes were in the range of 83.9-108.8%. These results indicate that graphene-modified TiO2 nanotube arrays exhibit good adsorption to the target pollutants, and the method described in this work could be used as a faster and easier alternative procedure for routine analysis of carbamate pesticides in real water samples.
Topics: Adsorption; Carbamates; Graphite; Nanotubes; Pesticides; Solid Phase Microextraction; Solvents; Time Factors; Titanium; Water; Water Pollutants, Chemical
PubMed: 25818138
DOI: 10.1016/j.aca.2015.02.019 -
Electrophoresis Mar 2015The applicability of an ionic liquid-based cationic surfactant 1-dodecyl-3-methyl-imidazolium tetrafluoroborate (C12 MImBF4 ) as pseudostationary phase in MEKC has been...
The applicability of an ionic liquid-based cationic surfactant 1-dodecyl-3-methyl-imidazolium tetrafluoroborate (C12 MImBF4 ) as pseudostationary phase in MEKC has been evaluated for the analysis of 11 carbamate pesticides (promecarb, carbofuran, metolcarb, fenobucarb, aldicarb, propoxur, asulam, benomyl, carbendazim, ethiofencarb, isoprocarb) in juice samples. Under optimum conditions (separation buffer, 35 mM NaHCO3 and 20 mM C12 MImBF4 , pH 9.0; capillary temperature 25°C; voltage -22 kV) the analysis was carried out in less than 12 min, using hydrodynamic injection (50 mbar for 7.5 s) and detection at 200 nm. For the extraction of these CRBs from juice samples, a dispersive liquid-liquid microextraction (DLLME) procedure has been proposed, by optimization of variables affecting the efficiency of the extraction. Following this treatment, sample throughput was approximately 12 samples per hour, obtaining a preconcentration factor of 20. Matrix-matched calibration curves were established using tomato juice as representative matrix (from 5 to 250 μg/L for CBZ, BY, PX, CF, FEN, ETH, ISP, and 25-250 μg/L for ASL, ALD, PRC, MTL), obtaining quantification limits ranging from 1 to 18 μg/L and recoveries from 70 to 96%, with RSDs lower than 9%.
Topics: Beverages; Borates; Carbamates; Chromatography, Micellar Electrokinetic Capillary; Imidazoles; Ionic Liquids; Linear Models; Solanum lycopersicum; Models, Chemical; Reproducibility of Results; Sensitivity and Specificity; Surface-Active Agents
PubMed: 25546365
DOI: 10.1002/elps.201400311 -
Biosensors & Bioelectronics Feb 2015In this work, we presented a three-dimensional (3D) molecularly imprinted electrochemical sensor (MIECS) with novel strategy for ultrasensitive and specific...
Prussian blue mediated amplification combined with signal enhancement of ordered mesoporous carbon for ultrasensitive and specific quantification of metolcarb by a three-dimensional molecularly imprinted electrochemical sensor.
In this work, we presented a three-dimensional (3D) molecularly imprinted electrochemical sensor (MIECS) with novel strategy for ultrasensitive and specific quantification of metolcarb based on prussian blue (PB) mediated amplification combined with signal enhancement of ordered mesoporous carbon. The molecularly imprinted polymers were synthesized by electrochemically induced redox polymerization of para aminobenzoic acid (p-ABA) in the presence of template metolcarb. Ordered mesoporous carbon material (CMK-3) was introduced to enhance the electrochemical response by improving the structure of the modified electrodes and facilitating charge transfer processes of PB which was used as an inherent electrochemical active probe. The modification process for the working electrodes of the MIECS was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV), and several important parameters controlling the performance of the MIECS were investigated and optimized in detail. The MIECS with 3D structure had the advantages of ease of preparation, high porous surface structure, speedy response, ultrasensitivity, selectivity, reliable stability, good reproducibility and repeatability. Under the optimal conditions, the MIECS offered an excellent current response for metolcarb in the linear response range of 5.0 × 10(-10)-1.0 × 10(-4) mol L(-1) and the limit of detection (LOD) was calculated to be 9.3 × 10 (-11)mol L(-1) (S/N = 3). The proposed MIECS has been successfully applied for the determination of metolcarb in real samples with satisfactory recoveries. Furthermore, the construction route of this ultrasensitive 3D MIECS may provide a guideline for the determination of non-electroactive analytes in environmental control and food safety.
Topics: Carbon; Conductometry; Electrodes; Equipment Design; Equipment Failure Analysis; Ferrocyanides; Molecular Imprinting; Pesticides; Phenylcarbamates; Porosity; Reproducibility of Results; Sensitivity and Specificity
PubMed: 25240126
DOI: 10.1016/j.bios.2014.09.009 -
Journal of Separation Science Dec 2014In the study, four different semiempirical algorithms, modified neglect of diatomic overlap, a reparameterization of Austin Model 1, complete neglect of differential...
In the study, four different semiempirical algorithms, modified neglect of diatomic overlap, a reparameterization of Austin Model 1, complete neglect of differential overlap and typed neglect of differential overlap, have been applied for the energy optimization of template, monomer, and template-monomer complexes of imprinted polymers. For phosmet-, estrone-, and metolcarb-imprinted polymers, the binding energies of template-monomer complexes were calculated and the docking configures were assessed in different molar ratio of template/monomer. It was found that two algorithms were not suitable for calculating the binding energy in template-monomers complex system. For the other algorithms, the obtained optimum molar ratio of template and monomers were consistent with the experimental results. Therefore, two algorithms have been selected and applied for the preparation of enrofloxacin-imprinted polymers. Meanwhile using a different molar ratio of template and monomer, we prepared imprinted polymers and nonimprinted polymers, and evaluated the adsorption to template. It was verified that the experimental results were in good agreement with the modeling results. As a result, the semiempirical algorithm had certain feasibility in designing the preparation of imprinted polymers.
Topics: Adsorption; Algorithms; Models, Chemical; Molecular Imprinting; Polymers
PubMed: 25229520
DOI: 10.1002/jssc.201400799 -
Journal of Hazardous Materials May 2014A technique for multiplex detection of organophosphorus pesticides and carbamate pesticides has been developed using a suspension array based on silica-hydrogel hybrid...
A technique for multiplex detection of organophosphorus pesticides and carbamate pesticides has been developed using a suspension array based on silica-hydrogel hybrid microbeads (SHHMs). The main advantage of SHHMs, which consist of both silica and hydrogel materials, is that they not only could be distinguished by their characteristic reflection peak originating from the stop-band of the photonic crystal but also have low non-specific adsorption of proteins. Using fluorescent immunoassay, the LODs for fenitrothion, chlorpyrifos-methyl, fenthion, carbaryl and metolcarb were measured to be 0.02ng/mL, 0.012ng/mL, 0.04ng/mL, 0.05ng/mL and 0.1ng/mL, respectively, all of which are much lower than the maximum residue limits, as reported in the European Union pesticides database. All the determination coefficients for these five pesticides were greater than 0.99, demonstrating excellent correlations. The suspension array was specific and had no significant cross-reactivity with other chemicals. The results for the detection of pesticide residues collected from agricultural samples using this method agree well with those from liquid chromatography-tandem mass spectrometry. Our results showed that this simple method is suitable for simultaneous detection of these five pesticides residues in fruits and vegetables.
Topics: Carbamates; Fruit; Hydrogels; Microspheres; Organophosphorus Compounds; Pesticides; Silicon Dioxide; Vegetables
PubMed: 24769809
DOI: 10.1016/j.jhazmat.2014.03.006 -
Food Chemistry Aug 2014Graphene reinforced hollow fibre liquid phase microextraction combined with high performance liquid chromatography-diode array detection was developed for the...
Extraction of carbamate pesticides in fruit samples by graphene reinforced hollow fibre liquid microextraction followed by high performance liquid chromatographic detection.
Graphene reinforced hollow fibre liquid phase microextraction combined with high performance liquid chromatography-diode array detection was developed for the determination of some carbamate pesticides (metolcarb, carbaryl, isoprocarb, and diethofencarb) in fruit samples. The main parameters that affect the extraction efficiency for the carbamates were investigated. Under the optimum conditions, a good linearity was observed in the range of 1.0-100.0 ng g(-1) for carbaryl and 3.0-100.0 ng g(-1) for the other three analytes, with the correlation coefficients (r) of 0.9965-0.9993. The limits of detection of the method ranged from 0.2 to 1.0 ng g(-1). The relative standard deviations were in the range from 6.2% to 7.8%. The results indicated that the developed method is sensitive and efficient for the determination of the carbamate pesticides in fruit samples.
Topics: Carbamates; Chromatography, High Pressure Liquid; Fruit; Graphite; Liquid Phase Microextraction; Pesticides
PubMed: 24679760
DOI: 10.1016/j.foodchem.2014.02.007 -
Journal of Chromatography. A Aug 2013A sensitive and selective gas chromatographic mass spectrometric method, based on derivatization with 9-xanthydrol, has been established for the simultaneous...
A sensitive and selective gas chromatographic mass spectrometric method, based on derivatization with 9-xanthydrol, has been established for the simultaneous determination of five carbamate pesticides (carbaryl, carbofuran, metolcarb, isoprocarb and ethiofencarb) in surface water. 4-Bromo-3,5-dimethylphenyl-N-methylcarbamate was chosen as the internal standard for analyzing water samples. The derivatization of carbamates was performed directly in water and the reaction conditions (9-xanthydrol of 50.0mM, HCl concentration of 0.05M, reaction for 60min at 60°C) were established through the optimization of various parameters. Under the established conditions, the limits of quantification were in the range of 0.007-0.028μg/L, and the intra- and inter-day relative standard deviation were each less than 15% at concentrations of 0.1, 1.0 and 10μg/L. None of the carbamate pesticides were detected in any of the sixteen surface waters analyzed.
Topics: Carbamates; Gas Chromatography-Mass Spectrometry; Limit of Detection; Pesticides; Reproducibility of Results; Water Pollutants, Chemical; Xanthenes
PubMed: 23890551
DOI: 10.1016/j.chroma.2013.07.055