Detection Of Carbamate Pesticides Research Articles

Determination of carboxylesterase by fluorescence probe to guide detection of carbamate pesticide.

A carboxylesterase fluorescent probe (Probe 1) was developed for determination of carboxylesterase to guide detection of carbamate pesticide. The probe uses benzothiazole as fluorescence group and phenyldimethyl carbamate as recognition group. The solution of the fluorescent probe gradually changes from light blue to dark blue as the concentration of carbamate pesticides increases. The concentration of carbamate pesticides can be quickly calculated according to the colour of the probe solution through Get Color software on a smartphone. It showed that Probe 1 can be used as a rapid detection tool to achieve rapid detection of carbamate pesticides in juice samples without professional personnel and equipment. Furthermore, the probe has been successfully used to detect carbamate pesticides in fruit juice and vegetable juice.

Colorimetric test strip cassette readout with a smartphone for on-site and rapid screening test of carbamate pesticides in vegetables

A test strip cassette integrated with a smartphone detector was developed for the colorimetric detection of carbamate pesticides in vegetables. The influence of various experimental conditions was examined for the detection of the optimum analytical performance of the test strip cassette. The test strip cassette detection of carbamate pesticides was carried out by using 140 mM of acetylthiocholine, 13 mM of 5,5′-dithiobis (2-nitrobenzoic acid), temperature at 37 °C and pH of 8.0. The developed test strip cassette platform is rapid within 5 min. Based on the inhibition effect of carbaryl on acetylcholinesterase activity, the inhibition effect of carbaryl was proportional to its concentration ranging from 1 to 50 mg/L with the detection limit of 0.30 mg/L. The limit of quantitative value was determined to be 1.0 mg/L. The spiking carbaryl, the recoveries were within 96–103% and the relative standard deviations were less than 1.56%. The analysis of carbamate pesticides residual in vegetable samples gave the results in good agreement with the most widely used commercial test kit and UPLC-MS/MS method. The developed test strip cassette required only 5 min for an assay. With the simple procedures and tiny size, it showed a great promising for the developed test strip to work on-site for carbamate pesticides detection in vegetables.

Microfluidic Paper Based Analytical Devices for the Detection of Carbamate Pesticides.

Microfluidic paper-based analytical devices (μ-PADs) are a new technology platform for the development of extremely low-cost sensing applications. In this study, μ-PADs has been developed for quantitative determination of carbamate pesticides. Key experimental parameters including concentration and volume of acetylcholinesterase, acetylthiocholine iodide and 5,5'-dithiobis-(2-nitrobenzoicacid), incubation time and image capturing time were systematically optimized. Under optimal conditions, the method showed wide range of linearity (0.25-16mg/L), repeatability (4%-5% RSD) and intermediate precision (7%-10% RSD). Limit of detection was observed to be 0.4, 0.24 and 0.46mg/L for carbaryl, carbosulfan and furathiocarb, respectively. An acceptable mean recovery (87% to 94%) was observed for the three pesticides at 1mg/L fortification level. The results reveal that the developed method requires minimal reagents, simple and is easy to handle. It can be used for the quantification of carbamate pesticides in resource limited laboratories without the need for the conventional analytical instruments.

Acetylcholinesterase Immobilized on Magnetic Mesoporous Silica Nanoparticles Coupled with Fluorescence Analysis for Rapid Detection of Carbamate Pesticides

Herein, we successfully synthesized a magnetic mesoporous material, Fe3O4@SiO2@mSiO2, and acetylcholinesterase (AChE) was immobilized by a covalent bonding method. The tolerance ability of immobilized AChE (by magnetic mesoporous silica nanoparticles) in different organic solvents was better than that of free AChE. Furthermore, the magnetic character of the fixed AChE improved the detection sensitivity and reliability for carbofuran, methomyl, isoprocarb, and carbaryl. The limit of detection (LOD) of carbofuran, methomyl, isoprocarb, and carbaryl was 0.01, 0.22, 0.26, and 0.43 μM, respectively. It shows a good correlation between carbamate pesticides (CMs) and the inhibition rate of Fe3O4@SiO2@mSiO2-AChE in a given concentration range. The linear ranges of carbofuran, methomyl, isoprocarb, and carbaryl were 0.02–0.90, 0.31–12.33, 0.27–5.17, and 0.50–14.91 μM, respectively. Chinese cabbage and cucumber spiked with four CMs were used as field-incurred samples to prove the feasibility of the developed method. According to the maximum residue limits, the results were satisfactory, with recovery rates between 77.03 and 110.07%, and the RSDs ranged from 3.17 to 6.79%. The stability of immobilized AChE in organic solvents was improved with enhanced sensitivity for detecting pesticide residues.

Fluorescence paper-based sensor for visual detection of carbamate pesticides in food based on CdTe quantum dot and nano ZnTPyP

The needing of rapid and sensitive detection method for pesticides is increasing, to facilitate its detection without complicated instruments. Herein, a novel paper-based senor was developed for the visual detection of three carbamate pesticides (metolcarb, carbofuran, and carbaryl) based on CdTe quantum dots (QDs) and nano zinc 5, 10, 15, 20-tetra(4-pyridyl)-21H-23H-porphine (nano ZnTPyP) with a “turn-off-on” mode. This fluorescence sensing model could be applied in the highly selective and sensitive detection of carbamate pesticides both by fluorescence spectrometry or paper-based sensors. Based on the extracted RGB color values of paper, the partial least squares regression (PLSR) was used to accurately quantify the concentrations of carbamate pesticides in different food matrices (apple, cabbage and tea water). This method featured in high speed, low price and high accuracy, and provided a new strategy for the detection of food safety.

Fluorescent turn-off sensor based on sulphur-doped graphene quantum dots in colloidal and film forms for the ultrasensitive detection of carbamate pesticides

Materials that are highly sensitive, easy-to-use, label-free and ultrafast detection of analyte molecules are in great demand. In the present global scenario, there is immense value to be gained from the development of materials that easily detect harmful substances like pesticides or insecticides in fruits and vegetables, environmental pollutants, or other hazardous chemicals. Herein, we demonstrated fluorescent sulphur-doped graphene quantum dots (S-GQDs)-based sensor for the ultrasensitive and selective detection of carbamate pesticides. Green fluorescent S-GQDs with uniform particle size distribution (~5 nm), high crystallinity, monolayer graphene thickness, high quantum yield (27.8%) and high production yield (85%) were synthesised by microwave-assisted sonochemical method using graphene oxide as starting material in five min. KMnO4 is used as oxidising agent and H2SO4 as the precursor for sulphur doping. Sulphur doping is confirmed from XPS and FTIR analysis. Sulphur-doping increases the fluorescence intensity, lifetime and quantum yield of GQDs. This heteroatom doping strategy also results in tuning the optical properties of S-GQD when compared to the undoped system. The green fluorescent S-GQDs in aqueous phase exhibits a detection limit of 0.45 ppb for carbofuran and 1.6 ppb for thiram. Further, S-GQD was incorporated to poly (vinyl alcohol) [PVA] matrix for the preparation of flexible solid-state fluorescent sensing platform. S-GQD imparts fluorescent properties to the polymer film, and thus the film exhibited solid-state fluorescence. PVA/S-GQD flexible film exhibits a LOD of 60 ppb and 210 ppb for carbofuran and thiram, respectively. The selectivity of S-GQD based fluorescent sensor towards carbamate pesticide was investigated. Finally, the developed fluorescent sensor has demonstrated to detect carbofuran in real sample with ppb level sensitivity.

Boron-doped diamond electrode acting as a voltammetric sensor for the detection of methomyl pesticide

Standard methods for the detection of carbamate pesticides are expensive, time-consuming, and require highly trained employees. Thus, electroanalytical methods are considered to be rapid, simple and low-cost alternatives. Here, we develop sensitive voltammetric methods for the determination of methomyl (a carbamate pesticide) using a bare boron-doped diamond electrode, square wave voltammetry (SWV), differential pulse voltammetry (DPV) and Britton–Robinson buffer (pH2.0) as supporting electrolyte. Methomyl has three oxidation processes: meantime process P1 was chosen for the analytical determination due to its higher sensitivity in comparison with other processes. The detection limits and concentration ranges of the SWV and DPV methods were 1.9×10−5 and 1.2×10−6molL−1, and 6.6–42.0×10−5 to 5.0–410.0×10−6molL−1, respectively. The proposed methods were successfully applied in river water, tap water and commercial formulations showcasing >80% mean recoveries. Comparing the two techniques, DPV was seen as the most sensitive method.

Electrochemical biosensing of carbaryl based on acetylcholinesterase immobilized onto electrochemically inducing porous graphene oxide network

This work describes a sensitive electrochemical biosensor for detection of carbamate pesticides based on immobilization of acetylcholinesterase (AChE) on the electrochemically inducing porous graphene oxide network (e-pGON) which is prepared by scanning the GO modified electrode using successive cyclic voltammetry method. The e-pGON effectively promotes the electron transfer rate and facilitates the access of substrates to the active centers. The as-prepared biosensor shows high affinity to acetylthiocholine (ATCl) with a Michaelis-Menten constant value of 0.45mmolL−1. Under optimum conditions, the inhibition of carbaryl is proportional to its concentration ranging from 0.3 to 6.1ng/mL. The detection limit is 0.15ng/mL. The developed biosensor exhibits good performance such as reproducibility and stability, thus providing a promising tool for the analysis of enzyme inhibitors.

Photoinduced chemiluminescence determination of carbamate pesticides.

A liquid chromatography method with post-column photoinduced chemiluminescence (PICL) detection is proposed for the simultaneous determination of eight carbamate pesticides, namely aldicarb, butocarboxim, ethiofencarb, methomyl, methiocarb, thiodicarb, thiofanox and thiophanate-methyl. After chromatographic separation, quinine (sensitizer) was incorporated and the flow passed through an UV lamp (67 s of irradiation time) to obtain the photoproducts, which reacted with acidic Ce(iv) and provided a CL emission. The PICL method showed great selectivity for carbamate pesticides containing sulphur in their chemical structure. A solid-phase extraction process increased sensitivity (LODs ranging from 0.06 to 0.27 ng mL(-1)) and allowed the carbamate pesticides in surface and ground water samples to be determined, with recoveries in the range 87-110% (except for thiophanate-methyl, whose recoveries were between 60 and 75%). The intra- and inter-day precision was evaluated, with RSD ranging from 1.1 to 7.5% and from 2.6 to 12.3%, respectively. A discussion about the PICL mechanism is also included.

Sensitive fluorescent detection of carbamate pesticides represented by methomyl based on the inner filter effect of Au nanoparticles on the fluorescence of CdTe quantum dots

Based on the inner filter effect (IFE) of Au nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs), a novel fluorescence method for the rapid assay of carbamate pesticides has been developed. The fluorescence of CdTe QDs was remarkably quenched in the presence of AuNPs via IFE. Acetylcholinesterase (AChE) catalyzed the hydrolysis of acetylthiocholine into thiocholine, which could induce the aggregation of AuNPs and decrease their characteristic absorption, thereby recovering the IFE-decreased fluorescence of the CdTe QDs. Carbamate pesticides can inhibit the activity of AChE, thus preventing the aggregation of AuNPs and the fluorescence recovery of CdTe QDs. Therefore, the IFE of the fluorescence between AuNPs and CdTe QDs could convert the absorption signal to a fluorescence signal, which improved the detection sensitivity of carbamate pesticides in vegetables. The calibration curve for methomyl was established in the range of 0.017–0.5 μg mL−1 with a detection limit of 0.011 μg mL−1 (S/N = 3) which is superior to the HPLC coupled with UV detection method. This method was successfully carried out for the assessment of methomyl in vegetables, and has many advantages such as high sensitivity, low cost and rapidity in comparison with traditional methods.

Carbaryl Detection by Gold Nanoparticles Electrodes for Fruit Application Model

A new method has been developed for the determination of carbaryl pesticides, , in water and fruit samples using gold nanoparticles electrode conductivity detection. The effects of pH on the binding between carbaryl and humic acid (HA) and number of layer coated electrode were investigated and optimized. HA modified the polyelectrolyte multilayer thin films (PEMs) coating electrode was used to detect carbaryl. The current was decreased 4.75% after dipping in HA for 10 minutes. The current was decreased around 7.28% from the initial value after HA binding with carbaryl. The results demonstrated that the newly developed method was an efficient procedure for the detection of carbamate pesticides in water.

Electrochemical detection of carbamate pesticides in fruit and vegetables with a biosensor based on acetylcholinesterase immobilised on a composite of polyaniline–carbon nanotubes

A sensitive electrochemical acetylcholinesterase (AChE) biosensor was successfully developed on polyaniline (PANI) and multi-walled carbon nanotubes (MWCNTs) core–shell modified glassy carbon electrode (GC), and used to detect carbamate pesticides in fruit and vegetables (apple, broccoli and cabbage). The pesticide biosensors were applied in the detection of carbaryl and methomyl pesticides in food samples using chronoamperometry (CA). The GC/MWCNT/PANI/AChE biosensor exhibited detection limits of 1.4 and 0.95μmolL−1, respectively, for carbaryl and methomyl. These detection limits were below the allowable concentrations set by Brazilian regulation standards for the samples in which these pesticides were analysed. Reproducibility and repeatability values of 2.6% and 3.2%, respectively, were obtained in the conventional procedure. The proposed biosensor was successfully applied in the determination of carbamate pesticides in cabbage, broccoli and apple samples without any spiking procedure. The obtained results were in full agreement with those from the HPLC procedure.

Cu@Ag/β-AgVO3 as a SERS substrate for the trace level detection of carbamate pesticides

A Surface Enhanced Raman Scattering (SERS) substrate based on Ag/β-AgVO3 nanobelts deposited on copper foil (Cu@Ag/β-AgVO3) was used for the detection of carbamate pesticides: carbofuran, carbaryl, isoprocarb and propoxur. Cu@Ag/β-AgVO3 has shown an excellent SERS activity for carbamate pesticides compared to silver nanoparticles (AgNPs). Under optimized conditions, detection limits of 2.5 pM, 10 pM, 50 pM and 75 pM were obtained for carbaryl, carbofuran, isoprocarb and propoxur respectively, suggesting that Cu@Ag/β-AgVO3 is a good candidate for use as a SERS substrate for the trace level detection of these pesticides.

Electrochemical detection of carbamate pesticides at conductive diamond electrodes.

Conductive boron-doped diamond thin-film electrodes were used for the electrochemical detection of selected N-methylcarbamate pesticides (carbaryl, carbofuran, methyl 2-benzimidazolecarbamate, bendiocarb) after liquid chromatographic separation. Two kinds of detection methods were adopted in this study. In the first method, a direct detection of underivatized pesticides was carried out at an operating potential of 1.45 V versus Ag/AgCl, which resulted in the detection limits of 5-20 ng/mL (or 5-20 ppb) with S/N = 2 due to the low background current and wide potential window of the diamond electrode. In the second method, the detection limits were improved by subjecting the pesticide samples to alkaline hydrolysis in a separate step prior to injection. The phenolic derivatives obtained by alkaline hydrolysis oxidize at a relatively lower potential (0.9 V vs Ag/AgCl), which increases the sensitivity drastically. The advantage of the diamond electrode for the detection of phenolic derivatives is that it offers excellent stability in comparison to other electrodes. This method gives the detection limits of 0.6-1 ng/mL (or 0.6-1 ppb), which are well below the maximum residue levels allowed for carbaryl, carbofuran, and bendiocarb. While the lowest detection limits (LOD) obtained by the direct detection of pesticides are comparable to the those reported by the well-established HPLC-fluorescence, the LODs of the alkaline hydrolysis method are found to be even lower than the reported limits. On-line reactivation of the diamond electrode surface was shown to be possible by an anodic treatment of the electrode at approximately 3 V for 30 min in case of electrode fouling, which may occur after a prolonged use. Such a treatment damages the glassy carbon (GC) and metal electrodes, while the diamond electrode remains stable. These results suggest that the diamond electrode is superior to the other previously used electrodes such as GC and Kelgraf type for highly sensitive and stable detection of carbamate pesticides.

Detection of carbamate pesticides in vegetable samples using cholinesterase‐based biosensors

AbstractBiosensors for determination of carbamates in vegetables based on five different cholinesterase as biorecognition elements and a screen‐printed electrode system as an amperometric transducer were developed. Measurements were simply performed by dropping solutions (either sample or substrate) directly on the biosensor. The response of biosensors to selected carbamates (aldicarb, carbaryl, carbofuran, methomyl and propoxur) was characterized. The performance was evaluated on extracts of potatoes and carrots, the results from the AChE biosensor and a standard HPLC procedure were compared. Finally, the biosensor was used for the direct analysis of vegetable juices without any pretreatment steps. In this case, 10 μg/L levels of added carbofuran and propoxur were reliably identified. The whole procedure takes less than 20 min including 10 min incubation with samples. The concentrations of carbamates determined with biosensor agreed well for carbofuran. Lower response was observed for propoxur.

Microarray electrochemical flow detectors at high applied potentials and liquid chromatography with electrochemical detection of carbamate pesticides in river water

Proprietes et avantages des microelectrodes de graphite comme detecteurs par rapport aux electrodes solides

Identification and detection of carbamate pesticides in autopsy tissues using thin-layer chromatography

Identification and detection of carbamate pesticides in autopsy tissues using thin-layer chromatography

A Fluorometric Enzyme Inhibition Detector for Carbamate Pesticide Analysis by High Speed Liquid Chromatography

Abstract A fluorometric enzyme inhibition detector has been developed for the detection of carbamate pesticides after separation using high speed liquid chromatography. Housefly head cholinesterase was found to have the greatest sensitivity toward the carbamates, together with horse plasma and bovine erythrocyte cholinesterases. The substrate N-methyl indoxyl acetate is used for monitoring of enzyme activity.

Enzymatic detection of carbamate pesticides on impregnated cellulose plates

The detection of carbamate pesticides by an enzyme-inhibition method on impregnated (ethylene glycol, triethylene glycol, beta,beta'-oxydipropionitrile) cellulose thin layer plates is described. The enzyme-substrate combination: pig liver esterase-indophenylacetate (chromogenic substrate) was the most sensitive. The following parameters concerning the sensitivity of the method were investigated: enzyme source, substrate, pH, inhibition time, inhibition temperature, thickness of the cellulose layer, stationary phase.