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Journal of AOAC International 2013A novel and fast competitive direct biomimetic ELISA (cd-BELISA) was developed for determination of the N-methylcarbamate insecticide metolcarb based on a molecularly...
Rapid determination of metolcarb residues in foods using a biomimetic enzyme-linked immunosorbent assay employing a novel molecularly imprinted polymer film as artificial antibody.
A novel and fast competitive direct biomimetic ELISA (cd-BELISA) was developed for determination of the N-methylcarbamate insecticide metolcarb based on a molecularly imprinted polymer (MIP) film as the antibody mimic. The MIP film was directly synthesized on the surface of a 96-well plate by bulk polymerization. The synthesized film was characterized, and the results showed that the imprinted film exhibited antibody-antigen-like binding properties and rapid adsorption ability, which was particularly useful for cd-BELISA development. The cd-BELISA conditions were optimized in detail. Under the optimum conditions, the sensitivity and LOD of the cd-BELISA were found to be 17 and 0.12 microg/L, respectively. Crossreactivity demonstrated that the cd-BELISA had a higher selectivity for metolcarb than for structurally related compounds. The developed method was applied to the determination of metolcarb in spiked apple juice, cabbage, and cucumber, with mean recoveries ranging from 71.5 to 117.0%. Validation of the results was conducted by HPLC with good correlation (r2 > 0.9562) between data obtained using these two methods. Therefore, the developed cd-BELISA has potential for the rapid determination of metolcarb in foods.
Topics: Antibodies; Enzyme-Linked Immunosorbent Assay; Food Contamination; Membranes, Artificial; Molecular Structure; Pesticide Residues; Pesticides; Phenylcarbamates; Polymers; Time Factors
PubMed: 23767373
DOI: 10.5740/jaoacint.10-387 -
Journal of Separation Science Apr 2013In this paper, a novel graphene (G) grafted silica-coated Fe3O4 nanocomposite was fabricated by the chemical bonding of G onto the surface of silica-coated Fe3 O4...
In this paper, a novel graphene (G) grafted silica-coated Fe3O4 nanocomposite was fabricated by the chemical bonding of G onto the surface of silica-coated Fe3 O4 nanoparticles. Some carbamates (metolcarb, carbaryl, pirimicarb, and diethofencarb) in cucumber and pear samples were enriched by this nanocomposite prior to their determination by HPLC with UV detection. Experimental parameters that may affect the extraction efficiency were investigated. Under the optimum conditions, a linear response was achieved in the concentration range of 0.5-100.0 ng/g for metolcarb, carbaryl, and diethofencarb, and 1.0-100 ng/g for pirimicarb with the correlation coefficients (r) ranging from 0.9956 to 0.9984. The LOD (S/N = 3) of the method were found to be in the range from 0.08 to 0.2 ng/g. The RSDs were in the range from 2.4 to 5.8%. The results indicated that the G grafted silica-coated Fe3 O4 nanocomposite was stable and efficient for magnetic SPE and has a great application potential for the preconcentration of other organic pollutants from real samples.
Topics: Carbamates; Chromatography, High Pressure Liquid; Cucumis sativus; Ferric Compounds; Graphite; Microscopy, Atomic Force; Nanocomposites; Pyrus; Silicon Dioxide
PubMed: 23404952
DOI: 10.1002/jssc.201201036 -
Electrophoresis May 2012A capillary electrophoresis immunoassay (CEIA) was developed for the determination of trace metolcarb (MTMC) in food. The method was based on the competitive reactions...
A capillary electrophoresis immunoassay (CEIA) was developed for the determination of trace metolcarb (MTMC) in food. The method was based on the competitive reactions between fluorescently labeled MTMC tracer and free MTMC with a limited amount of anti-MTMC antibody and the separation and determination by CE with LIF detector. A fluorescent reagent, FITC was labeled on MTMC to construct an immunofluorescent probe. CEIA experimental parameters such as the pH value and concentration of the running buffer and separation voltage as well as incubation time were systematically investigated. Under the optimized conditions, fluorescently labeled antigen and antibody bound could be well separated within 3 min using Na₂B₄O₇/NaH₂PO₄ buffer (20:10 mmol/L, pH 9.0) for background electrolyte, 20 kV for the separation voltage, and 20°C for the column temperature. The linear range of the method was 0.25-50.0 μg/L with LOD 0.07 μg/L. The RSD for relative migration time and relative fluorescence intensity ratio were 2.90% (intraday) and 4.73% (intraday), respectively. The proposed method has been applied to determine the residue of MTMC in food samples with the satisfactory recovery.
Topics: Animals; Antibodies; Cucumis sativus; Electrophoresis, Capillary; Female; Food Analysis; Hydrogen-Ion Concentration; Immunoassay; Limit of Detection; Oryza; Pesticide Residues; Phenylcarbamates; Rabbits; Reproducibility of Results; Spectrometry, Fluorescence
PubMed: 22648817
DOI: 10.1002/elps.201100704 -
Journal of Economic Entomology Feb 2012Both chemical and biological methods are essential for control of insects, for example, lepidopterans, on rice. Thus, it is important to know the effect of chemicals on...
Both chemical and biological methods are essential for control of insects, for example, lepidopterans, on rice. Thus, it is important to know the effect of chemicals on the biological control agents. In this study, we assessed the toxicity of commonly used insecticides on a biological control agent, Trichogramma japonicum Ahmead (an egg parasitoid of rice lepidopterans) by using a dry film residue method. Results showed that thirty insecticides from seven chemical classes exhibited various degree of toxicity to this parasitoid. Among the seven classes of chemicals tested, organophosphates (chlorpyrifos, fenitrothion, phoxim, profenofos, and triazophos) and carbamates (carbaryl, carbsulfan, isoprocarb, metolcarb, and promecarb) exhibited the highest intrinsic toxicity to T. japponicum, with an LC50 of 0.035 (0.029-0.044) to 0.49 (0.34-0.87) mg active ingredient (a.i.) L(-1), followed by antibiotics (abamectin, emamectin benzoate, and ivermectin), phenylpyrazoles (butane-fipronil, ethiprole, and fipronil), pyrethroids (cyhalthrin, cypermethrin, fenpropathrin, and lambda-cyhaothrin), and neonicotinoids (acetamiprid, imidacloprid, imidaclothiz, nitenpyram, thiacloprid, and thiamethoxam). Moreover, the insect growth regulator insecticides (chlorfluazuron, fufenozide, hexaflumuron and tebufenozide) exhibited the lowest toxicity to the wasps with an LC50 of 3,383 (2406-5499) to 30206 (23107-41008) mg ai. L(-1). Risk quotient analysis showed that phenylpyrazoles, pyrethroids, insect growth regulators, neonicotinoids (with the exception of thiamethoxam), and antibiotics (with the exception of abamectin) are classified as safe agents to the parasitoid, while organophosphates and carbamates are classified as slightly, moderately, or highly toxic agents to the parasitoid. The data presented in this paper provided useful information on the selection of compatible insecticides with T. japonicum.
Topics: Animals; Biological Control Agents; Dose-Response Relationship, Drug; Insecticides; Lethal Dose 50; Moths; Oryza; Risk Assessment; Toxicity Tests; Wasps
PubMed: 22420260
DOI: 10.1603/ec11259 -
Journal of Chromatography. A Nov 2011A graphene-based magnetic nanocomposite was synthesized and used for the first time as an effective adsorbent for the preconcentration of the five carbamate pesticides...
A graphene-based magnetic nanocomposite was synthesized and used for the first time as an effective adsorbent for the preconcentration of the five carbamate pesticides (metolcarb, carbofuran, pirimicarb, isoprocarb and diethofencarb) in environmental water samples prior to high performance liquid chromatography-diode array detection. The properties of the magnetic nanocomposite were characterized by scanning electron microscopy and X-ray diffraction. This novel graphene-based magnetic nanocomposite showed great adsorptive ability towards the analytes. The method, which takes the advantages of both nanoparticle adsorption and magnetic phase separation from the sample solution, could avoid some of the time-consuming experimental procedures related to the traditional solid phase extraction. Various experimental parameters that could affect the extraction efficiencies have been investigated. Under the optimum conditions, the enrichment factors of the method for the analytes were in the range from 474 to 868. A linear response was achieved in the concentration range of 0.1-50 ng mL(-1). The limits of detection of the method at a signal to noise ratio of 3 for the pesticides were 0.02-0.04 ng mL(-1). Compared with the dispersive liquid-liquid microextraction and the ultrasound-assisted surfactant-enhanced emulsification microextraction, much higher enrichment factors and sensitivities were achieved with the developed method. The method has been successfully applied for the determination of the carbamate pesticides in environmental water samples.
Topics: Adsorption; Carbamates; Chemical Fractionation; Chromatography, High Pressure Liquid; Graphite; Hydrogen-Ion Concentration; Magnets; Microscopy, Electron, Scanning; Nanocomposites; Pesticides; Reproducibility of Results; Rivers; Sensitivity and Specificity; Water Pollutants, Chemical; Water Supply
PubMed: 21962496
DOI: 10.1016/j.chroma.2011.09.027 -
Analytica Chimica Acta Apr 2011A molecularly imprinted film is electrochemically synthesized on a gold electrode using cyclic voltammetry to electropolymerize o-aminothiophenol in the presence of...
A molecularly imprinted film is electrochemically synthesized on a gold electrode using cyclic voltammetry to electropolymerize o-aminothiophenol in the presence of metolcarb (MTMC). The mechanism of the imprinting process and a number of factors affecting the activity of the imprinted film are discussed and optimized. Scanning electron microscope observations and binding measurements have proved that an MTMC-imprinted film (with a thickness of nearly 100 nm) was formed on the surface of the gold electrode. The film exhibited high binding affinity and selectivity towards the template MTMC, as well as good penetrability, reproducibility and stability. A novel amperometry sensor using the imprinted film as recognition element was developed for MTMC determination in food samples. Under the experimental conditions, the MTMC standard is linear within the concentration range studied (r(2)=0.9906). The limit of detection (S/N=3) of the modified electrode was achieved to 1.34×10(-8) mol L(-1). Recoveries of MTMC from spiked apple juice, cabbage and cucumber samples for the developed electrochemical assay ranged from 94.80% to 102.43%, which was with great correlation coefficient (0.9929) with results from high-performance liquid chromatography. In practical application, the prepared amperometric sensor also showed good reproducibility and long lifetime for storage. The research in this study has offered a rapid, accurate and sensitive electrochemical method for quantitative determination of MTMC in food products.
Topics: Electrochemical Techniques; Electrodes; Gold; Limit of Detection; Molecular Imprinting; Pesticides; Phenylcarbamates; Vegetables
PubMed: 21435473
DOI: 10.1016/j.aca.2011.02.034 -
Journal of Agricultural and Food... Dec 2010In biological systems, bivalent ligands often possess increased functional affinity for their receptors compared with monovalent ligands. On the basis of the structure...
In biological systems, bivalent ligands often possess increased functional affinity for their receptors compared with monovalent ligands. On the basis of the structure of acetylcholinesterase (AChE), a series of novel carbamate heterodimetic derivatives were designed and synthesized with the aim of increasing the potency toward AChE inhibition. The AChE inhibitory ability of all the novel compounds was tested using AChE obtained from the brain of the housefly. The bioassay results showed that compounds 6j, 6k, 6m, 6n, 6p, and 6q had increased inhibitory activities in comparison with parent phenyl N-methylcarbamate (MH) at the concentration of 100 mg/L. Among them, the most potent AChE inhibitor of these compounds was 6q (IC(50) = 12 μM), which showed 62-fold greater AChE inhibitory activity than that of MH and 12-fold greater activity than metolcarb (MT), which suggested that the 3-nitrophenoxy moiety of compound 6q was able to interact with the aromatic amino acid residues lining the gorge and the phenyl N-methylcarbamate moiety was able to interact with the catalytic sites of AChE, simultaneously. The insecticidal activities of compounds 6j, 6k, 6m, 6n, 6p, and 6q were further evaluated. Consistent with the result in vitro bioassay, those compounds demonstrated better activities against Lipaphis erysimi than parent compound MH at the concentration of 300 mg/L, and compound 6q showed the best insecticidal activity, causing 98% mortality after 24 h of treatment.
Topics: Acetylcholinesterase; Animals; Aphids; Binding Sites; Brain; Carbamates; Cholinesterase Inhibitors; Houseflies; Insecticides; Molecular Structure; Structure-Activity Relationship
PubMed: 21114293
DOI: 10.1021/jf1032284 -
Chemosphere Aug 2010Mutagenic and genotoxic effects of metolcarb were investigated by both bacterial reverse mutation assay in Salmonella typhimurium TA97, TA98, TA100 and TA102 strains...
Mutagenic and genotoxic effects of metolcarb were investigated by both bacterial reverse mutation assay in Salmonella typhimurium TA97, TA98, TA100 and TA102 strains with or without metabolic activation system (S9) and Allium cepa root meristematic cells, respectively. Metolcarb was dissolved in DMSO in Ames/Salmonella test system. 0.1, 1 and 10 microg/plate doses of metolcarb were found to be mutagenic S. typhimurium TA98 without S9. In Allium root growth inhibition test, EC50 value was determined 200 ppm and 0.5xEC50, EC50 and 2xEC50 concentrations of metolcarb were introduced to onion tuber roots and distilled water used as a negative control. Mitotic index (MI), increased in all concentrations compared to control at each exposure time. While disturbed anaphase-telophase, chromosome laggards, stickiness and bridges were observed in anaphase-telophase cells, pro-metaphase, C-mitosis, polyploidy, binuclear cells and disturbed nucleus were observed in other cells. The results were also analyzed statistically by using SPSS for Windows, Mann-Whitney test and Duncan's multiple range tests were performed respectively.
Topics: Anaphase; Environmental Exposure; Mitosis; Mutagenicity Tests; Mutagens; Onions; Phenylcarbamates; Plant Roots; Polyploidy; Salmonella typhimurium; Telophase; Time Factors; Water Pollutants, Chemical
PubMed: 20605189
DOI: 10.1016/j.chemosphere.2010.05.011 -
Journal of Separation Science Jul 2010In this article, for the first time, a molecularly imprinted polymer (MIP) for the metolcarb was prepared by bulk polymerization using metolcarb as the template,...
In this article, for the first time, a molecularly imprinted polymer (MIP) for the metolcarb was prepared by bulk polymerization using metolcarb as the template, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The prepared polymer was characterized by FT-IR, static and kinetic adsorption experiments, and the results showed that it has been successfully synthesized and had good selective ability for metolcarb. The MIP was applied as a sorbent in molecularly imprinted SPE coupled with HPLC-UV for separation and determination of trace metolcarb in three kinds of food matrices at three concentration levels. Under the optimal conditions, the LODs (S/N=3) of cabbage, cucumber and pear were 7.622, 6.455 and 13.52 microg/kg, respectively, and recoveries were in the range of 68.80-101.31% with RSD (n=3) below 3.78% in all cases. To demonstrate further the selectivity of the MIP obtained, a comparison with commercially available C(18) SPE was performed. The results indicated that molecularly imprinted SPE showed better chromatography, better selectivity and higher recoveries for metolcarb than commercially available C(18) SPE.
Topics: Adsorption; Chromatography, High Pressure Liquid; Food Contamination; Molecular Imprinting; Molecular Structure; Phenylcarbamates; Polymers; Spectroscopy, Fourier Transform Infrared
PubMed: 20552596
DOI: 10.1002/jssc.200900877 -
Analytica Chimica Acta May 2010A direct competitive enzyme linked immunosorbent assay in multi-enzyme tracers format for the simultaneous analysis of carbaryl and metolcarb in agricultural products is...
A direct competitive enzyme linked immunosorbent assay in multi-enzyme tracers format for the simultaneous analysis of carbaryl and metolcarb in agricultural products is described in this study. The concentrations of coating antibodies and enzyme tracer were studied. Under the optimum conditions, the limits of detection of carbaryl and metolcarb were 0.15 microg L(-1) and 1.2 microg L(-1), respectively. Determination of carbaryl and metolcarb in fruit juices and vegetables was accomplished by simple, rapid and efficient extraction methods. Recoveries of spiked samples were great than 70%. Validation of the immunosorbent assay was conducted by comparison of results from high performance liquid chromatography (HPLC). The correlations between the data obtained using multi-enzyme tracers enzyme linked immunosorbent assay and high performance liquid chromatography were good. Results indicated that the new strategy for developing immunoassay for simultaneous quantitative determination of carbaryl and metolcarb residues was suitable in this study.
Topics: Agriculture; Animals; Antibodies; Beverages; Carbaryl; Enzyme-Linked Immunosorbent Assay; Enzymes; Feasibility Studies; Malus; Pesticide Residues; Phenylcarbamates; Reproducibility of Results; Time Factors; Vegetables
PubMed: 20433968
DOI: 10.1016/j.aca.2010.03.051