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Food Additives & Contaminants. Part A,... Mar 2010A direct competitive enzyme-linked immunosorbent assay (ELISA) with enhanced chemiluminescent detection for simultaneous detection of metolcarb and carbaryl in...
A direct competitive enzyme-linked immunosorbent assay (ELISA) with enhanced chemiluminescent detection for simultaneous detection of metolcarb and carbaryl in agricultural products is reported. The concentrations of coating antibodies and enzyme tracer, as well as the effects of pH and methanol concentrations, were investigated. Under optimum conditions, the IC(50) of metolcarb and carbaryl were 4 and 0.3 microg kg(-1), respectively. Detection of metolcarb and carbaryl in fruit juices and vegetables was accomplished using simple, rapid and efficient extraction methods. Recoveries (n = 3) of spiked samples ranged 75-108% for metolcarb and 74-98% for carbaryl. Validation of the enhanced chemiluminescent immunosorbent assay was conducted by comparison of results with HPLC. The correlation between the data obtained using ELISA with enhanced chemiluminescent detection and HPLC was good (n = 9). Therefore, the enhanced chemiluminescent ELISA was suitable for quantitative simultaneously determination of metolcarb and carbaryl residue in agricultural products.
Topics: Beverages; Brassica; Carbaryl; Citrus sinensis; Cucumis sativus; Enzyme-Linked Immunosorbent Assay; Fruit; Insecticides; Luminescent Measurements; Molecular Structure; Pesticide Residues; Phenylcarbamates; Reproducibility of Results; Sensitivity and Specificity
PubMed: 20155539
DOI: 10.1080/19440040903403016 -
Journal of Chromatography. A Mar 2010A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) coupled with high performance liquid chromatography-diode array detection has...
Ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of carbamate pesticides in water samples by high performance liquid chromatography.
A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) coupled with high performance liquid chromatography-diode array detection has been developed for the extraction and determination of six carbamate pesticides (metolcarb, carbofuran, carbaryl, pirimicarb, isoprocarb and diethofencarb) in water samples. In the UASEME technique, Tween 20 was used as emulsifier, and chlorobenzene and chloroform were used as dual extraction solvent without using any organic dispersive solvent that is normally required in the previously described common dispersive liquid-liquid microextraction method. Parameters that affect the extraction efficiency, such as the kind and volume of the extraction solvent, the type and concentration of the surfactant, ultrasound emulsification time and salt addition, were investigated and optimized for the method. Under the optimum conditions, the enrichment factors were in the range between 170 and 246. The limits of detection of the method were 0.1-0.3 ng mL(-1) and the limits of quantification were between 0.3 and 0.9 ng mL(-1), depending on the compounds. The linearity of the method was obtained in the range of 0.3-200 ng mL(-1) for metolcarb, carbaryl, pirimicarb, and diethofencarb, 0.6-200 ng mL(-1) for carbofuran, and 0.9-200 ng mL(-1) for isoprocarb, with the correlation coefficients (r) ranging from 0.9982 to 0.9998. The relative standard deviations varied from 3.2 to 4.8% (n=5). The recoveries of the method for the six carbamates from water samples at spiking levels of 1.0, 10.0, 50.0 and 100.0 ng mL(-1) were ranged from 81.0 to 97.5%. The proposed UASEME technique has demonstrated to be simple, practical and environmentally friendly for the determination of carbamates residues in river, reservoir and well water samples.
Topics: Carbamates; Chemical Fractionation; Chlorobenzenes; Chloroform; Chromatography, High Pressure Liquid; Emulsions; Fresh Water; Linear Models; Pesticides; Polysorbates; Reproducibility of Results; Sensitivity and Specificity; Sodium Chloride; Surface-Active Agents; Temperature; Ultrasonics
PubMed: 20138627
DOI: 10.1016/j.chroma.2010.01.060 -
Spectrochimica Acta. Part A, Molecular... Dec 2009A new analytical method was developed for the simultaneous kinetic spectrophotometric determination of a quaternary carbamate pesticide mixture consisting of carbofuran,...
Sequential injection kinetic spectrophotometric determination of quaternary mixtures of carbamate pesticides in water and fruit samples using artificial neural networks for multivariate calibration.
A new analytical method was developed for the simultaneous kinetic spectrophotometric determination of a quaternary carbamate pesticide mixture consisting of carbofuran, propoxur, metolcarb and fenobucarb using sequential injection analysis (SIA). The procedure was based upon the different kinetic properties between the analytes reacted with reagent in flow system in the non-stopped-flow mode, in which their hydrolysis products coupled with diazotized p-nitroaniline in an alkaline medium to form the corresponding colored complexes. The absorbance data from SIA peak time profile were recorded at 510 nm and resolved by the use of back-propagation-artificial neural network (BP-ANN) algorithms for multivariate quantitative analysis. The experimental variables and main network parameters were optimized and each of the pesticides could be determined in the concentration range of 0.5-10.0 microg mL(-1), at a sampling frequency of 18 h(-1). The proposed method was compared to other spectrophotometric methods for simultaneous determination of mixtures of carbamate pesticides, and it was proved to be adequately reliable and was successfully applied to the simultaneous determination of the four pesticide residues in water and fruit samples, obtaining the satisfactory results based on recovery studies (84.7-116.0%).
Topics: Absorption; Aniline Compounds; Calibration; Carbamates; Fruit; Hydrolysis; Kinetics; Multivariate Analysis; Neural Networks, Computer; Pesticides; Sodium Hydroxide; Spectrophotometry; Time Factors; Water
PubMed: 19864181
DOI: 10.1016/j.saa.2009.09.030 -
Analytical and Bioanalytical Chemistry Aug 2009The development of a direct competitive enzyme-linked immunosorbent assay based on polyclonal antibodies for N-methylcarbamate insecticide metolcarb is described. Two...
The development of a direct competitive enzyme-linked immunosorbent assay based on polyclonal antibodies for N-methylcarbamate insecticide metolcarb is described. Two new haptens for the metolcarb were designed and synthesized. Both haptens were conjugated with keyhole limpet hemocyanin to form the immunogens. Four rabbits were immunized with the immunogens for production of polyclonal antibodies against metolcarb. Antisera titers were tested on the homologous coating antigens using a noncompetitive indirect enzyme-linked immunosorbent assay. The high titer antisera were used to develop the direct competitive enzyme-linked immunosorbent assay for the detection of metolcarb. The antibody-antigen combination with the highest selectivity for metolcarb was further optimized and its tolerance to changes in chemical conditions (ionic strength, pH value, and organic solvent) was studied. Under optimum conditions, the sensitivity and the limit of detection were determined to be 22 microg L(-1) and 1.2 microg L(-1) respectively. Determination of metolcarb in fruit juices and vegetables was accomplished by simple, rapid, and efficient extraction methods. Recoveries of metolcarb from spiked samples ranged from 80.5% to 109.5%. Validation of the developed immunosorbent assay was conducted by comparison of results from high-performance liquid chromatography. The correlation between the data obtained using developed immunosorbent assay and high-performance liquid chromatography was high (R2 = 0.9884). Therefore, the developed immunosorbent assay in this study was suitable for the rapid quantitative determination of metolcarb in agricultural products.
Topics: Animals; Antibodies; Beverages; Enzyme-Linked Immunosorbent Assay; Food Contamination; Haptens; Immune Sera; Pesticide Residues; Phenylcarbamates; Sensitivity and Specificity; Time Factors; Vegetables
PubMed: 19575189
DOI: 10.1007/s00216-009-2911-9 -
Guang Pu Xue Yu Guang Pu Fen Xi = Guang... Jan 2009In the present paper, the fluorescence spectra of three common pesticides, isoprocarb, metolcarb and pirimicarb, were theoretically studied. The geometries of these...
In the present paper, the fluorescence spectra of three common pesticides, isoprocarb, metolcarb and pirimicarb, were theoretically studied. The geometries of these compounds were fully optimized by density function theory (DFT) method at the B3LYP/6-31+G level. The three compounds under study were confirmed as true minima on the potential energy surface in the presence of only real frequencies by the vibrational analysis. The fluorescence spectra were calculated by configuration interaction (CI) method with PCM model, and the results match with the experimental values. The results of calculation suggest that the three compounds with planar structures are hyperconjugation systems. By the addition of the donor-electron groups, the wavelengths of the fluorescence spectra increased, and the frequencies underwent red-shift. In addition, the substitute alkyl has no more influence on the fluorescence spectra, but the addition of amido groups has more influence on the fluorescence spectra.
Topics: Fluorescence; Hydrocarbons, Aromatic; Models, Chemical; Quantum Theory; Spectrometry, Fluorescence; Spectrophotometry, Infrared; Spectrum Analysis, Raman
PubMed: 19385231
DOI: No ID Found -
Talanta Jun 2004A high performance liquid chromatography with fluorescence (HPLC-F) detector was examined to simultaneous determination of airborne carbamates in the workplace of...
A high performance liquid chromatography with fluorescence (HPLC-F) detector was examined to simultaneous determination of airborne carbamates in the workplace of manufactory. The OVS-2 air sampling tube filled with glass fiber filter or quartz fiber and combined filter/XAD-2 were evaluated to collect nine commonly used carbamates (Carbofuran, Isoprocarb, Methomyl, Metolcarb, Thiodicarb, Carbaryl, Oxamyl, Methiocarb, and Prpoxur) from the air of manufactory in high humidity country. After being extracted with acetonitrile from sampling tubes, the carbamates were determined by high performance liquid chromatography with fluorescence detection posterior to on-line derivatization. The collection of carbamates and the recovery of extraction from glass wool fiber in several concentration levels, and from quartz filter were evaluated. The storage stability of carbamates was also tested. Results indicated that the HPLC-fluorescence method offers satisfactory resolution and sensitivity in carbamate analysis. With the glass fiber filter and combined filter/XAD-2, the Carbofuran, Isoprocarb, Methomyl, Metolcarb, and Thiodicarb were stable for a 28-day storage test, Carbaryl and Oxamyl for 14 days, and Methiocarb and Prpoxur for 7 days. All of these pesticides were with detection limit of 3mugm(-3). It is suited for environmental monitoring. The airborne carbamates in different areas of the manufactory were measured.
PubMed: 18969467
DOI: 10.1016/j.talanta.2003.11.031 -
Journal of Chromatographic Science Sep 2008A method for the determination of metolcarb and diethofencarb in apples and apple juice is developed using solid-phase microextraction (SPME) coupled with...
A method for the determination of metolcarb and diethofencarb in apples and apple juice is developed using solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC). The experimental conditions of SPME, such as the kind of extraction fiber, extraction time, stirring rate, pH of the extracting solution, and desorption conditions are optimized. The SPME is performed on a 60 microm polydimethylsiloxane/divinylbenzene fiber for 40 min at room temperature with the solution being stirred at 1100 rpm. The extracted pesticides on the SPME fiber are desorbed in the mobile phase into SPME-HPLC interface for HPLC analysis. Separations are carried out on a Baseline C18 column (4.6 i.d. x 250 mm, 5.0 microm) with acetonitrile-water (55/45, v/v) as the mobile phase at a flow rate of 1.0 mL/min, and photodiode-array detection at 210 nm. For apple samples, the method is linear for both metolcarb and diethofencarb in the range of 0.05-1.0 mg/kg (r > 0.99), with a detection limit (S/N = 3 ) of 15 and 5 microg/kg, respectively. For apple juice, the method is linear for both metholcarb and diethofencarb over the range of 0.05-1.0 mg/L (r > 0.99) with the detection limit (S/N = 3 ) of 15 and 3 microg/L, respectively. Excellent recovery and reproducibility values are achieved. The proposed method is shown to be simple, sensitive, and organic solvent-free, and is suitable for the determination of the two pesticides in apples and apple juice.
Topics: Beverages; Calibration; Chromatography, High Pressure Liquid; Hydrogen-Ion Concentration; Malus; Osmolar Concentration; Phenylcarbamates; Reproducibility of Results; Sensitivity and Specificity; Temperature
PubMed: 18796236
DOI: 10.1093/chromsci/46.8.751 -
Analytica Chimica Acta Sep 2008Five different haptens of the N-methylcarbamate insecticide metolcarb were designed and synthesized. All of the haptens were conjugated with ovalbumin (OVA) for the...
Five different haptens of the N-methylcarbamate insecticide metolcarb were designed and synthesized. All of the haptens were conjugated with ovalbumin (OVA) for the coating antigen, and one hapten containing all of the structure of metolcarb was conjugated with bovine serum albumin (BSA) for the immunogen. Two polyclonal antisera were raised against the BSA conjugate, and ten antibody/coating conjugate combinations were selected for studies of assay sensitivity and specificity for metolcarb. A class-specific combination was found, with the I50 of the assay ranged from 0.64 to 20.98 microg mL(-1) for seven tested N-methylcarbamate insecticides except for pirimicarb. Considering titer, I50 and cross-reactivity of all combinations of antibody/coating conjugate, a competitive indirect enzyme-linked immunosorbent assay (ELISA) in a homologous system, whose limit of detection (LoD) reached 1.4 ng mL(-1), was presented. The results of competitive ELISAs indicated that coating hapten structure can significantly affect not only assay sensitivity but also its specificity.
Topics: Animals; Carbamates; Cattle; Enzyme-Linked Immunosorbent Assay; Haptens; Immune Sera; Insecticides; Reproducibility of Results; Sensitivity and Specificity
PubMed: 18721544
DOI: 10.1016/j.aca.2008.07.003 -
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 -
Talanta Feb 2007In this paper, a polyamide-modified carbon paste electrode in capillary zone electrophoresis with amperometric detection (CZE-AD) was firstly applied to the...
In this paper, a polyamide-modified carbon paste electrode in capillary zone electrophoresis with amperometric detection (CZE-AD) was firstly applied to the determination of four carbamate pesticides: fenobucarb, isoprocarb, metolcarb and carbaryl. The four carbamates were hydrolyzed in alkalescent aqueous solutions, resulting in the formation of 2-sec-butylphenol, 2-isopropylphenol, m-cresol and alpha-naphthol, which could be determined by amperometry after capillary electrophoretic separation. Under the selected optimum conditions, the four analytes could be perfectly separated within 23min. The linear ranges of 2-sec-butylphenol, 2-isopropylphenol and m-cresol were from 1.0x10(-7) to 2.0x10(-5)molL(-1) and that of alpha-naphthol was from 2.0x10(-7) to 2.0x10(-5)molL(-1) and their detection limits were 3.0x10(-8), 3.0x10(-8), 3.0x10(-8) and 6.0x10(-8)molL(-1), respectively (S/N=3). Fenobucarb, isoprocarb, metolcarb and carbaryl can be indirectly determined by this CZE-AD method with recovery of 105, 104, 110 and 98% and R.S.D. of 4, 3, 4 and 3%, respectively. Above results demonstrated that this method was of high sensitivity, good repeatability and could be used in the rapid determination of the pesticide residues.
PubMed: 19071416
DOI: 10.1016/j.talanta.2006.06.001