-
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 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 -
Analytical and Bioanalytical Chemistry May 2021The long-term consumption of food with pesticide residues has harmful effects on human health and the demand for pesticide detection technology tends to be miniaturized...
The long-term consumption of food with pesticide residues has harmful effects on human health and the demand for pesticide detection technology tends to be miniaturized and instant. To this end, we demonstrated the first application of indirectly detecting two carbamate pesticides, metolcarb and carbaryl, by gold nanoparticle-modified indium tin oxide electrode in dual-channel microchip electrophoresis and amperometric detection (ME-AD) system. m-Cresol and α-naphthol were obtained after pesticide hydrolysis in alkaline solution, and then separated and detected by ME-AD. Parameters including the detection potential and running buffer concentration and pH were optimized to improve the detection sensitivity and separation efficiency. Under the optimal conditions, the two analytes were completely separated within 80 s. m-Cresol and α-naphthol presented a wide linear range from 1 to 100 μM, with limits of detection of 0.16 μM and 0.34 μM, respectively (S/N = 3). Moreover, the reliability of this system was demonstrated by analyzing metolcarb and carbaryl in spiked vegetable samples.
Topics: Carbamates; Electrochemical Techniques; Electrophoresis, Microchip; Limit of Detection; Pesticide Residues; Reference Standards; Reproducibility of Results; Vegetables
PubMed: 33635387
DOI: 10.1007/s00216-021-03237-3 -
Rapid Communications in Mass... Sep 2008Flowing afterglow atmospheric pressure glow discharge tandem mass spectrometry (APGD-MS/MS) is used for the analysis of trace amounts of pesticides in fruit juices and...
Flowing afterglow atmospheric pressure glow discharge tandem mass spectrometry (APGD-MS/MS) is used for the analysis of trace amounts of pesticides in fruit juices and on fruit peel. The APGD source was rebuilt after Andrade et al. (Andrade et al., Anal. Chem. 2008; 80: 2646-2653; 2654-2663) and mounted onto a hybrid quadrupole time-of-flight mass spectrometer. Apple, cranberry, grape and orange juices as well as fruit peel and salad leaves were spiked with aqueous solutions containing trace amounts of the pesticides alachlor, atrazine, carbendazim, carbofuran, dinoseb, isoproturon, metolachlor, metolcarb, propoxur and simazine. Best limits of determination (LODs) of pesticides in the fruit juices were achieved for metolcarb (1 microg/L in apple juice), carbofuran and dinoseb (2 microg/L in apple juice); for the analysis of apple skin best LODs were 10 pg/cm(2) of atrazine, metolcarb and propoxur which corresponds to an estimated concentration of 0.01 microg/kg apple, taking into account the surface area and the weight of the apple. The measured LODs were within or below the allowed maximum residue levels (MRLs) decreed by the European Union (1-500 microg/kg for pesticides in fruit juice and 0.01-5 microg/kg for apple skin). No sample pretreatment (extraction, pre-concentration, chromatographic separation) was necessary to analyze these pesticides by direct desorption/ionization using APGD-MS and to identify them using MS/MS. This makes APGD-MS a powerful high-throughput tool for the investigation of very low amounts of pesticides in fruit juices and on fruit peel/vegetable skin.
Topics: Atmospheric Pressure; Food Analysis; Food Contamination; Mass Spectrometry; Pesticides
PubMed: 18697232
DOI: 10.1002/rcm.3677 -
Analytica Chimica Acta Mar 2020We report herein the design of a novel electrochemical sensing strategy for sensitive detection of pesticide based on graphitic carbon nitride (g-CN)/graphene oxide(GO)...
We report herein the design of a novel electrochemical sensing strategy for sensitive detection of pesticide based on graphitic carbon nitride (g-CN)/graphene oxide(GO) nanocomposite covalently bound to a ferrocene containing dendrimer(Fc-TED). The g-CN with sufficient N atoms for providing lone pairs of electrons to an electron acceptor so as to enhance the adsorption towards organic molecules. The Fc-TED dendrimers with the native redox signaling center (Fe/Fe) can increase the electron transition of g-CN from valence to conduction band. While GO can accelerate the electron transfer from g-CN surface and Fc-TED to glassy carbon electrode(GCE), which would amplify the electrochemical signal of g-CN/GO/Fc-TED/GCE sensor and then improve the sensing performance. It is found that the fabricated electrode demonstrated an admirable electrochemical sensing performance towards metolcarb in terms of low detection limit (8.3 nM), wide concentration range (0.045-213 μM) and rapid response time (2s). The proposed sensor can selectively detect the metolcarb and easily discriminated metolcarb from the possible interfering species. The practical applicability of the sensor was successfully evaluated in real vegetable sample and achieved satisfactory recoveries with good precision and accuracy.
Topics: Biosensing Techniques; Dendrimers; Electrochemical Techniques; Electrodes; Ferrous Compounds; Food Contamination; Graphite; Limit of Detection; Metallocenes; Nanocomposites; Nitrogen Compounds; Oxidation-Reduction; Pesticide Residues; Phenylcarbamates; Spinacia oleracea
PubMed: 32081192
DOI: 10.1016/j.aca.2019.12.066 -
Bioorganic & Medicinal Chemistry Jun 2019A series of new doramectin derivatives containing carbamate, ester and sulfonate were synthesized, and their structures were characterized by H and C nuclear magnetic...
A series of new doramectin derivatives containing carbamate, ester and sulfonate were synthesized, and their structures were characterized by H and C nuclear magnetic resonance (NMR) and high-resolution mass spectrum (HRMS). Their insecticidal activities against oriental armyworm, diamondback moth, and corn borer were evaluated and compared with the parent doramectin and commercial avermectins, metolcarb, fenpropathrin. Among all compounds, three compounds (3a, 3g and 3h) showed excellent insecticidal effect. In particular, compound 3g containing cyclopropyl carbamate against oriental armyworm, diamondback moth, and corn borer, exhibited the most promising insecticidal activity with the final mortality rate of 66.67%, 36.67%, 40.00% at the concentration of 12.5 mg/L, respectively. The LC values of 3g were 5.8859, 22.3214, and 22.0205 mg/L, showing 6.74, 2.23, 2.21-fold higher potency than parent doramectin (LC values of 39.6907, 49.7736, and 48.6129 mg/L) and 6.83, 1.93, 3.36-fold higher potency than commercial avermectins (LC values of 40.2489, 42.9922, and 73.9508 mg/L). Additionally, molecular docking simulations revealed that 3g displayed stronger hydrogen-bonding action in binding with the GABA receptor than parent doramectin, which were crucial for keeping high insecticidal activity. The present work demonstrated that these compounds containing alkyl carbamate group could be considered as potential candidates for the development of novel pesticides in the future.
Topics: Animals; Binding Sites; Drug Design; Insecticides; Ivermectin; Molecular Docking Simulation; Molecular Structure; Moths; Phenylcarbamates; Pyrethrins; Receptors, GABA; Structure-Activity Relationship
PubMed: 30626556
DOI: 10.1016/j.bmc.2018.12.040 -
Analytical Methods : Advancing Methods... Aug 2022High-temperature comprehensive two-dimensional gas chromatography (HTGC × GC) using a longitudinally modulated cryogenic system (LMCS) was developed for the analysis of...
High-temperature comprehensive two-dimensional gas chromatography (HTGC × GC) using a longitudinally modulated cryogenic system (LMCS) was developed for the analysis of low-volatility pesticides in cabbage. The method applied DB-17HT and DB-5HT as the first and second dimensional (D and D) columns, respectively. Twelve pesticides, namely 6 organochlorines (4,4'-DDT, β-endosulfan, endosulfan sulfate, endrin, heptachlor, and dicofol), 4 carbamates (metolcarb, isoprocarb, methiocarb, and carbofuran), 1 organophosphate (chlorpyrifos), and 1 pyrethroid (permethrin), were spiked into cabbage samples and prepared using QuEChERS. The applied oven temperature was up to 340 °C, enabling the elution of all the target pesticides and the matrix. The effects of initial oven temperature program, temperature ramp rate, LMCS trap temperature, and modulation period () on the separation results were investigated, leading to the suitable conditions of 80 °C, 15 °C min, 10 °C, and 12 s, respectively. The method detection limits, signal-to-noise ratio, and recoveries of the compounds were within the ranges of 0.01-0.09 mg kg, 4.26-32.7, and 78-104%, respectively. Good linearity ranges within the concentration range of 0.1-1 ppm with > 0.9134 were also obtained with the intra and interday precisions of the peak areas of 0.4-9.8% and 1.0-10.2%, respectively.
Topics: Brassica; Chromatography, Gas; Hydrocarbons, Chlorinated; Pesticides; Temperature
PubMed: 35929731
DOI: 10.1039/d2ay00998f -
Analytical Methods : Advancing Methods... Oct 2022Carbamate (CB) pesticides possess potential carcinogenic and mutagenic activities towards humans even at very low dosages. Thus, broad-specificity probes with high...
Carbamate (CB) pesticides possess potential carcinogenic and mutagenic activities towards humans even at very low dosages. Thus, broad-specificity probes with high sensitivity and speed are needed for multiple CB determination. This study is the first to focus on Dy ions-coordinated self-assembly on a silica core using a surface imprinting procedure, for the simultaneous fluorometric detection of residues of metolcarb (MC) and pirimicarb (PC) insecticides. A simple and mild solvothermal method was applied for the preparation of fluorescent imprinted microspheres starting from 1,10-phenanthroline (Phen)-ligated Dy ions to guide imprinted self-assembly of chitosan (CTS), glutaraldehyde (GA), and two carbamate pesticides (MC and PC) on the silica surface by means of coordinate bonds and hydrogen bonds. The as-prepared microspheres displayed strong fluorescence emissions the antenna effect derived from the Phen ligand and the Schiff base oligomers for sensitizing the Dy ions. An expanded in-depth mechanism study was performed on the fluorescence enhancement involving Förster resonance energy transfer (FRET) from the pesticides (donor) to the acceptor. A linear increase in fluorescence at 483 nm for MC and 574 nm for PC upon the imprinted microspheres was observed under the same 350 nm excitation wavelength. Moreover, the quantitative recognition process could be carried out simultaneously and tolerate strong distractions both from five other similar carbamate insecticides and from complicated matrices (, an extract of Ramat). The detection limit was 4 ng mL with a range of 10-60 ng mL for MC and 0.4 ng mL with a range of 1-30 ng mL for PC. Further characterization of the material, including TEM, SEM, XPS, and FTIR, Raman, and fluorescence spectra, verified that the Dy ions play a decisive role in promoting imprinted self-assembly around the silica core. Hence, a novel polynuclear Ln-organic imprinted probe having high selectivity, stability, and sensitivity for the detection of two carbamate insecticides is presented in this study.
Topics: Humans; Silicon Dioxide; Microspheres; Molecular Imprinting; Insecticides; Pesticides; Carbamates
PubMed: 36197096
DOI: 10.1039/d2ay01269c -
Food Research International (Ottawa,... Apr 2023The honeysuckle was widely appreciated as tea beverage owing to the biological activities and the unique aroma and flavor. It is in urgent requirement to explore the...
Migration behavior and dietary exposure risk assessment of pesticides residues in honeysuckle (Lonicera japonica Thunb.) based on modified QuEChERS method coupled with tandem mass spectrometry.
The honeysuckle was widely appreciated as tea beverage owing to the biological activities and the unique aroma and flavor. It is in urgent requirement to explore the migration behavior and dietary exposure as the pesticide residues would bring about potential risks through honeysuckle intake. The optimized QuEChERS procedure coupled with the HPLC-MS/MS and GC-MS/MS methods were employed to determine 93 pesticide residues of seven classifications including carbamates, pyrethroid, triazoles, neonicotinoids, organophosphorus, organochlorine, and others for 93 honeysuckle samples from four primary production bases. As a result, 86.02% of the samples were contaminated by at least one pesticide. Unexpectedly, the banned pesticide of carbofuran was also identified. The migration behavior of metolcarb was the highest, whereas thiabendazole contributed less risk to the infusion with relative lower transfer rate. Both the chronic and acute exposure yielded low risk for human health with five high risk pesticides of dichlorvos, cyhalothrin, carbofuran, ethomyl, and pyridaben. Besides, this study provides foundation of dietary exposure risk assessment for honeysuckle and other likewise products.
Topics: Humans; Pesticide Residues; Tandem Mass Spectrometry; Lonicera; Carbofuran; Dietary Exposure; Pesticides; Risk Assessment
PubMed: 36914339
DOI: 10.1016/j.foodres.2023.112572 -
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