Detection Of Carbofuran Research Articles

Electrochemical sensor based on molecularly imprinted polymer reduced graphene oxide and gold nanoparticles modified electrode for detection of carbofuran

A new molecularly imprinted electrochemical sensor was fabricated based on glassy carbon electrode decorated by reduced graphene oxide and gold nanoparticles (rGO@Au) for the detection of carbofuran (CBF). The molecularly imprinted polymers (MIPs) were prepared on the electrode surface with CBF as the template molecule, methyl acrylic acid as the functional monomer, and ethylene glycol maleic rosinate acrylate (EGMRA) as a cross-linker. The sensor was studied with respect to its response to hexacyanoferrate as a probe and characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, the peak current of the sensor and CBF concentration showed a good linear relationship over the range from 5.0×10−8 to 2.0×10−5mol/L, with a detection limit of 2.0×10−8mol/L (S/N=3). The sensor exhibited high adsorption capacity and good selectivity for CBF and it was successfully applied to the detection of CBF in real vegetable samples.

Biosensor based on Butyrylcholinesterase for Detection of Carbofuran

Esterase enzymes play an important role in biology because they are responsible for the hydrolysis of choline esters. In their absence, the original state of the post synaptic membranes cannot be reestablished. Therefore, the aim of the work is to study the inhibiting action exerted by the group of compounds on these enzymes. Among these class of inhibiting compounds, pesticides are important because of the potential danger as a result of their large scale use in agriculture. Pesticides are generally determined using liquid or gas chromatography methods with various detection techniques. These methods are very sensitive and discriminating, however they require sample pretreatment such as extraction, preconcentration and clean up, which are skilled techniques and high cost treatment and also time consuming. In this study, acetyl cholinesterase and butyrylcholinesterase based biosensors have emerged as a promising tool for the detection and characterization of pesticides which are inhibitors of these enzymes. Although the physiological function of butyrylcholinesterase in comparison with acetyl cholinesterase is ambiguous, it has larger substrate specificity towards choline esters. Therefore, the development of a more selective electrode against choline, can lead to more sensitive determination of the inhibitor being investigated. Hence in the present work, a method based on inhibition of butyrylcholinesterase was attempted for quantification of carbofuran on the basis of cholinesterase inhibition. Butyrylcholinesterase with an activity of 10.2 units/mg was immobilized on a solid surface by cross linking with glutaraldehyde. The immobilized system was calibrated by correlating the inhibition of the butyrylcholinesterase activity with varying concentrations of the butyryl choline chloride and carbofuran. The sensing mechanism was investigated for its response to carbofuran concentrations ranging from 125 to 1,000 ppm. The effects of butyryl choline chloride concentration on the response of the sensing strip were also determined. Through this work, a sensing element made up of a carbon based electrode, containing the immobilized butyrylcholinesterase, has been described. This element has certain practical advantages like smaller size, user friendly, easy portability and disposability.

Construction of an impedimetric immunosensor for label-free detecting carbofuran residual in agricultural and environmental samples

In this paper, a label-free electrochemical impedance immunosensor for the detection of carbofuran was prepared by immobilizing l-cysteine on a gold electrode. The carbofuran antibodies were immobilized on the electrode by the using glutaraldehyde as a cross linker. The stepwise assembly of the electrode surface was confirmed by atomic force microscope (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, a linear relationship between the resistance change and the logarithm value of carbofuran concentration was obtained in the carbofuran concentration range of 1.0 × 10−1 – 1.0 × 103 ng/mL, with a detection limit of 1.0 × 10−1 ng/mL. The immunosensor performed good reproducibility and stability. Additionally, the proposed method can be applied for monitoring carbofuran residual in agricultural and environmental samples.

DEVELOPMENT OF A BIOMIMETIC SENSOR MODIFIED WITH HEMIN AND GRAPHENE OXIDE FOR MONITORING OF CARBOFURAN IN FOOD

A biomimetic sensor based on a carbon paste electrode modified with hemin complex and graphene oxide was developed as an alternative technique for the sensitive and selective analysis of carbofuran pesticide. The electrochemical analysis of carbofuran was initially carried out with the biomimetic sensor using cyclic voltammetry within the potential range of -0.2 to 0.8V vs. Ag/AgCl (KClsat). The sensor showed in square wave voltammetry (SWV) a linear response between 5.0×10−6 and 9.5×10−5molL−1, a sensitivity of 1.1×105 (±1.4×103) μA L mol−1 and detection limit of 9.0×10−9molL−1. The sensitive and selective detection of carbofuran was confirmed through the analysis of other pesticides using SWV. When the proposed sensor was applied in food samples, the results obtained in the recovery studies were found to be close to 100%. These results obtained were similar to those of the high performance liquid chromatography (HPLC) method. Furthermore, an electrochemical study was conducted aiming at verifying the importance of the use of hemin complex and graphene oxide in the construction of the sensor. The results obtained showed a clear improvement in selectivity, reproducibility and sensitivity of the proposed sensor.

English

In this paper the results for the construction of a gold/mercaptobenzothiazole/polyaniline/ acetylcholinesterase/polyvinylacetate (Au/ MBT/PANI/AChE/PVAc) thick-film biosensor for the determination of certain carbamate pesticide solutions in selected aqueous organic sol- vent solutions are reported. AChE biosensors are designed to complement the classical analytical methods of pesticide detection. The Au/ MBT/PANI/AChE/PVAc electrocatalytic biosensor device was constructed by encapsulating acetylcholinesterase (AChE) enzyme in the PANI polymer composite, followed by the coating of poly(vinyl acetate) (PVAc) on top to secure the biosensor film from disintegration in the organic solvents evaluated. The electroactive substrate called acetylthiocholine (ATCh) was employed to provide the movement of electrons in the amperometric biosensor. The voltammetric results have shown that the current shifts more anodically as the Au/MBT/PANI/AChE/PVAc bio- sensor responded to successive acetylthiocholine (ATCh) substrate addition under anaerobic conditions in 0.1 M phosphate buffer, KCl (pH 7.2) solution and aqueous organic solvent solutions. For the Au/MBT/PANI/AChE/PVAc biosensor, various performance and stability parame- ters were evaluated. These factors include the optimal enzyme loading, effect of pH, long-term stability of the biosensor, temperature stability of the biosensor, the effect of polar organic solvents, and the effect of non-polar organic solvents on the amperometric behavior of the biosen- sor. The biosensor constructed in this study offered a reasonable linear range between 0.25 to 3.45 nM for the detection of carbofuran, al- dicarb and dioxacarb pesticide solutions. The detection limits for the individual carbamate pesticides were 0.249 nM for carbofuran, followed by 1.209 nM for aldicarb and 1.572 nM for dioxacarb.

Electrochemical nonenzymatic sensor based on CoO decorated reduced graphene oxide for the simultaneous determination of carbofuran and carbaryl in fruits and vegetables

A novel nonenzymatic sensor based on cobalt (II) oxide (CoO)-decorated reduced graphene oxide (rGO) was developed for the detection of carbofuran (CBF) and carbaryl (CBR). Two well-defined and separate differential pulse voltammetric peaks for CBF and CBR were obtained with the CoO/rGO sensor in a mixed solution, making the simultaneous detection of both carbamate pesticides possible. The nonenzymatic sensor demonstrated a linear relationship over a wide concentration range of 0.2–70μM (R=0.9996) for CBF and 0.5–200μM (R=0.9995) for CBR. The lower detection limit of the sensor was 4.2μg/L for CBF and 7.5μg/L for CBR (S/N=3). The developed sensor was used to detect CBF and CBR in fruit and vegetable samples and yielded satisfactory results.

Amperometric Immunosensor for Carbofuran Detection Based on MWCNTs/GS-PEI-Au and AuNPs-Antibody Conjugate

In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs) and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au) nanocomposites were modified onto the surface of a glass carbon electrode (GCE) via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab) and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD), ultraviolet and visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM), respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3). The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication.

Alkaline Phosphatase Inhibition-Based Amperometric Biosensor for the Detection of Carbofuran

Alkaline Phosphatase Inhibition-Based Amperometric Biosensor for the Detection of Carbofuran

Detection of Carbofuran with Immobilized Acetylcholinesterase Based on Carbon Nanotubes‐Chitosan Modified Electrode

A sensitive and stable enzyme biosensor based on efficient immobilization of acetylcholinesterase (AChE) to MWNTs‐modified glassy carbon electrode (GCE) with chitosan (CS) by layer‐by‐layer (LBL) technique for rapid determination of carbofuran has been devised. According to the inhibitory effect of carbamate pesticide on the enzymatic activity of AChE, we use carbofuran as a model pesticide. The inhibitory effect of carbofuran on the biosensor was proportional to concentration of carbofuran in the range from 10−10 g/L to 10−3 g/L with a detection limit of 10−12 g/L. This biosensor is a promising new method for pesticide analysis.

Amperometric immunosensor for carbofuran detection based on gold nanoparticles and PB-MWCNTs-CTS composite film

An electrochemical immunosensor has been developed for the determination of carbofuran based on gold nanoparticles (DpAu), prussian blue-multiwalled carbon nanotubes-chitosan (PB-MWCNTs-CTS) nanocomposite film and protein A (SPA) layer-by-layer assemble technology. DpAu and PB-MWCNTs-CTS incorporated films were used to enhance the electroactivity and stability of the immunosensor. The porous three-dimensional PB-MWCNTs-CTS nanocomposite film provided many amino groups and carboxyl groups to cross-link SPA and offered a large specific surface area to immobilize SPA. The formation of a self-assembled SPA layer was employed onto the electrode surface to increase the binding capacity of the antibody. The conformational process of the immunosensor and electrochemical performance of immunoreaction between carbofuran and the anti-carbofuran monoclonal antibody were characterized by cyclic voltammetry and electrochemical impedance spectroscopy, respectively. Effects of experimental variables, such as the concentration of the SPA and antibody, the adsorption time of DpAu, the pH of supporting electrolyte and the incubation time, were investigated in details. Under optimum operating conditions, the system provided a wide linear range between 0.1 and 1 μg/mL with a low detection limit of 0.021 ng/mL. The proposed immunosensor exhibited high sensitivity, high stability and good reproducibility, and it can be used for the detection of carbofuran pesticide.

Amperometric Immunosensor Based on Gold Nanoparticles and Saturated Thiourea for Carbofuran Detection

A new label-free immunosensor for the determination of carbofuran was proposed in this paper. Saturated thiourea (TU) and gold nanoparticles (GNPs) were modified onto the glassy carbon electrode surface to form a GNPs/TU film, which provided an interface containing-NH2 to assemble the second GNPs for the immobilization of anti-carbofuran antibody. Bovine serum albumin was used for blocking the non-specific adsorption sites. Thus, a novel amperometric immunosensor for carbofuran was prepared. The electrochemical properties of the modified processes were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Under the optimal conditions, the current response was proportional to the concentration of carbofuran ranging from 1.0 ng/mL to 100.0 ng/mL and from 100.0 ng/mL to 200 μg/mL with the detection limit 0.11 ng/mL. The proposed amperometric immunosensor exhibited high sensitivity, low cost and simplified procedures, which provided a new promising tool for the detection of pesticides residues in food and environment.

A label-free electrochemical immunosensor for carbofuran detection based on a sol-gel entrapped antibody.

In this study, an anti-carbofuran monoclonal antibody (Ab) was immobilized on the surface of a glassy carbon electrode (GCE) using silica sol-gel (SiSG) technology. Thus, a sensitive, label-free electrochemical immunosensor for the direct determination of carbofuran was developed. The electrochemical performance of immunoreaction of antigen with the anti-carbofuran monoclonal antibody was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), in which phosphate buffer solution containing [Fe(CN)6]3−/4− was used as the base solution for test. Because the complex formed by the immunoreaction hindered the diffusion of [Fe(CN)6]3−/4− on the electrode surface, the redox peak current of the immunosensor in the CV obviously decreased with the increase of the carbofuran concentration. The pH of working solution, the concentration of Ab and the incubation time of carbofuran were studied to ensure the sensitivity and conductivity of the immunosensor. Under the optimal conditions, the linear range of the proposed immunosensor for the determination of carbofuran was from 1 ng/mL to 100 μg/mL and from 50 μg/mL to 200 μg/mL with a detection limit of 0.33 ng/mL (S/N = 3). The proposed immunosensor exhibited good high sensitivity and stability, and it was thus suitable for trace detection of carbofuran pesticide residues.

Construction of a Simple Portable Optical Sensor Based on Air Stable Lipid Film with Incorporated Acetylcholinesterase for the Rapid Detection of Carbofuran in Foods

This work describes the construction of a simple portable optical biosensor for the rapid, selective, and sensitive detection of carbofuran in foods using air stable lipid films with incorporated acetylcholinesterase. The stabilized substance supported on a polymer lipid film on a glass fiber filter was formed on the filter by polymerization using UV (ultra-violet) radiation prior its use. Methacrylic acid was the functional monomer, ethylene glycol dimethacrylate was the crosslinker, and 2,2′-azobis-(2-methylpropionitrile) was the initiator. Acetylcholinesterase was incorporated within this mixture prior to the polymerization. The polymerization process took place by using UV irradiation. The polymerized lipid films without this enzyme provided fluorescence under a UV lamp. The presence of the enzyme in these films quenched this fluorescence. A drop of aqueous solution of acetylcholine provided a “switching on” of the fluorescence, which allowed the rapid detection of this compound at the levels of 10−8 M concentrations. These lipid membranes were used for the rapid detection of pesticides. Carbofuran was chosen as a typical pesticide. A drop of carbofuran in the filters quenched again the fluorescence. Carbofuran could be determined at concentration levels of 10−7 to 10−9 M. The investigation of the effect of potent interferences included a wide range of compounds usually found in foods and also of proteins and lipids. The technique was applied in real samples of fruits, vegetables, and dairy products. This allowed the rapid detection of the pesticide in markets and in the field.

Determination of carbofuran in fish and corn leaves by two types of commercial immunoassays

We evaluated two commercially available immunoassay kits for the detection of carbofuran in fish and corn leaves. We observed strong matrix interference or inhibition due to the extraction solvent. This interference was corrected by either diluting or decolorizing and diluting the extract. The coefficient of variation of the recovery ranged from 3.9 - 11.0% for the coated tubes compared to 1.3 - 3.9% for magnetic particles bases kits. We detected carbofuran in the range of 0.33 - 0.51 ng/g in fish and 0.75 - 2.20 ng/g in corn leaf. The ELISA detection limits were 0.5 ng/g in corn leaf and 0.3 ng/g in fish fillet. The samples, which were positive for carbofuran (by kits) were found to contain carbofuran (by GLC) with a good coefficient of correlation (r2 = 0.997). These results showed that ELISA can be used for the determination of pesticides in the environment, but observed cross reactivity with the metabolites may interfere with the detection of the parent compound and hinder the detection. The possibility of false positive or false negative detection may require the use of chromatography as confirmation technique. In any case, ELISA is advantageous to developing countries because of the low cost of material acquisition. Key words: ELISA, kit, carbofuran, fish, leaf, polystyrene tube, magnetic particles.

Layer-by-Layer self-assembled acetylcholinesterase/PAMAM-Au on CNTs modified electrode for sensing pesticides

In this paper, an acetylcholinesterase (AChE)/dendrimers polyamidoamine (PAMAM)-Au/Carbon nanotubes (CNTs) multilayer modified electrode based on LbL self-assembled technique was employed in the detection of carbofuran in samples. The configuration of the nanostructure on the electrode provided a favorable environment to the immobilization of AChE. The modified films also improved the electrocatalytic characteristics and electron transfer speed between the films and the surface of electrode. The PAMAM-Au nanoparticles were characterized by SEM and UV-VIS methods. A set of experimental conditions were also optimized for the detection of the pesticides. A linear response over carbofuran concentration in the range of 4.8x10(-9)M to 0.9x10(-7)M was exhibited with a detection limit of 4.0x10(-9)M. The biosensor showed high sensitivity, good stability and reproducibility with promising application.

Gold immunochromatographic assay for simultaneous detection of carbofuran and triazophos in water samples

Using a simple test for rapid identification and quantification of pesticide multiresidues in food and environmental samples is a long-cherished approach for practical monitoring purposes. Here two gold-based lateral-flow strips (strip A and strip B) were investigated for simultaneous detection of carbofuran and triazophos. For the strip A format, a bispecific monoclonal antibody (BsMcAb) against both carbofuran and triazophos was employed to prepare the immunogold probe. For the strip B format, anti-carbofuran monoclonal antibody (McAb) and anti-triazophos McAb separately labeled with colloidal gold were combined as detector reagents. By comparison of visual results from pesticide standard tests between the two formats, the strip B assay manifested higher sensitivities for both pesticides. Analysis of spiked water samples by the preferable strip indicated that the detection limits for carbofuran and triazophos were 32 and 4 μg/L, respectively. The strength of the portable one-step strip assay was in the simultaneous screening for two pesticides within a short time (8–10 min) without any equipment.

Lab-on-a-chip for ultrasensitive detection of carbofuran by enzymatic inhibition with replacement of enzyme using magnetic beads

In this paper an ultrasensitive method to determine toxicity due to pesticides in a glass lab-on-a-chip by means of enzymatic inhibition of acetylcholinesterase immobilised on magnetic beads is described. The reproducible insertion of a controlled amount of enzyme-coupled magnetic beads inside the chip channel and their immobilisation in a capture region with the aid of a magnetic field has been optimised. This procedure enables the easy renewal of the biosensing material after each determination in a highly reproducible manner. Several operational parameters such as the working potential for the selective detection of thiocholine (TCh) on a platinum disc electrode, the TCh detection reproducibility and sensitivity, the electroosmotic flow driving voltage and the inhibition time were also evaluated or optimised. The detection of carbofuran (one of the most toxic carbamate pesticides) has been achieved down to the nanomolar level.

Development of an Electrochemical Biosensor for the Rapid Detection of Carbofuran Based on Air Stable Lipid Films with Incorporated Calix[4]arene Phosphoryl Receptor

AbstractThis work describes the preparation of a selective receptor for the rapid, selective and sensitive electrochemical flow injection analysis of carbofuran in foods using air stable lipid films supported on a methacrylate polymer on a glass fiber filter with incorporated artificial receptor. The selective receptor was synthesized by transformation of the OH groups of resorcin[4]arene receptor into phosphoryl groups. These lipid films were supported on a methylacrylate polymer (i.e., methacrylic acid was the functional monomer for the polymerization, ethylene glycol dimethacrylate was used as the crosslinker and 2,2′‐azobis‐2‐methylpropionitrile as an initiator). A minisensor device was constructed for the electrochemical flow injection analysis of toxicants based on air stabilized lipid films supported on a polymer. The device can sense the analyte in a drop (50 μL) of sample. Carbofuran was injected into flowing streams of a carrier electrolyte solution. A host‐guest complex formation between the calix[4]arene phosphoryl receptor and carbofuran takes place through hydrogen bonding. This enhances the preconcentration of carbofuran at the lipid membrane surface which in turn causes dynamic alterations of the electrostatic fields and phase structure of membranes; as a result ion current transients were obtained and the magnitude of these signals was correlated to the substrate concentration. The response times were ca. 80 s and carbofuran was determined at concentration levels of nM. The effect of potent interferences included a wide range of compounds and other insecticides. The effect of interference of proteins and lipids was also examined. The reproducibility of the method was checked by recovery experiments in fruit and vegetable samples with satisfactory results.

Preparation of a selective receptor for carbofuran for the development of a simple optical spot test for its rapid detection using stabilized in air lipid films with incorporated receptor

The present technique describes the preparation of a selective receptor for carbofuran and the development of a simple sensitive spot optical test for the rapid one-shot detection of carbofuran using stabilized lipid films supported on a methacrylate polymer on a glass fiber filter with incorporated artificial receptor. The selective receptor was synthesized by a chemical reaction using a resorcin[4]arene receptor by transforming all the –OH groups into phosphoryl groups. The lipid films without this receptor provided fluorescence under a UV lamp. The use of the receptor in these films quenched this fluorescence and the colour became similar to that of the filters without the lipid films. A drop of aqueous solution of carbofuran provided a “switching on” of the fluorescence which allows the rapid detection of this insecticide at the levels of 10 −9 M concentrations. The effect of potent interferences included a wide range of compounds. The results showed no interferences from these compounds in concentration levels usually found in real samples. The effect of interference of proteins and lipids was also examined. The reproducibility of the method was checked in about 100 samples and all of them were found to provide similar results. The device was tested/evaluated in real samples of fruits, vegetables and dairy products. Note that the colours of the filters remain stable for periods of more than 2 months.

Development of an enzyme-linked immuno-sorbent assay (ELISA) method for carbofuran residues.

The haptens 4-[[(2,3-dihydro-2,2-dimethyl-7-benzofuranyloxy)carbonyl]-amino]butanoic acid (BFNB) and 6-[((2,3-dihydro-2,2-dimethyl-7-benzofuranyloxy)-carbonylamino]hexanoic acid (BFNH) were synthesized and then used to develop a rapid, specific and sensitive ELISA method to determine residues of the pesticide carbofuran in a variety of matrices. A hybridoma cell line (5D3) producing anti-carbofuran monoclonal antibodies (MAbs) was also established. Based on the MAbs in combination with the heterologous hapten BFNH coupled to either horseradish peroxidase (HRP) or ovalbumin (OVA), four ELISAs (formats I-IV) for the quantification of carbofuran were developed and compared. Among them, the optimized format II (the conjugate-coated direct competitive ELISA) showed the best characteristics, with an IC50 value of 18.49 ng/mL, a limit of detection of 0.11 ng/mL and the shortest assay time (1 h). This ELISA method was then applied to the determinations of carbofuran in environmental water, soil and food samples. The relative standard deviations (R.S.D.s) ranged from 1.8% to 21.3% and the mean recoveries were 104.6%, 108.3%, 106.3% and 100.1% for water, soil, lettuce and cabbage, respectively. Thus, the ELISA method of format II exhibited the potential to develop commercial ELISA kits for a rapid detection of carbofuran for human health and environmental safety.