Extraction and Detection of Pesticides by Cholinesterase Inhibition in a Two‐Phase System: a Strategy to Avoid Heavy Metal Interference (original) (raw)
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Determination of binary pesticide mixtures by an acetylcholinesterase–choline oxidase biosensor
Biosensors and Bioelectronics, 2004
In this study, acetylcholinesterase (AChE) and choline oxidase (ChO) were co-immobilized on poly(2-hydroxyethyl methacrylate) (pHEMA) membranes to construct a biosensor for the detection of anti-cholinesterase compounds. pHEMA membranes were prepared with the addition of SnCl 4 to achieve the desired porosity. Immobilization of the enzymes was done by surface attachment via epichlorohydrin (Epi) and Cibacron Blue F3G-A (CB) activation. Enzyme immobilized membrane was used in the detection of anti-cholinesterase activity of aldicarb (AS), carbofuran (CF) and carbaryl (CL), as well as two mixtures, (AS + CF) and (AS + CL). The total anti-cholinesterase activity of binary pesticide mixtures was found to be lower than the sum of the individual inhibition values.
Comparative investigation of electrochemical cholinesterase biosensors for pesticide determination
Analytica Chimica Acta, 2000
A number of potentiometric biosensors based on cholinesterases from various sources have been developed and examined for the determination of Co-Ral and Trichlorfon to establish factors affecting the analytical performance of biosensors. Acetylcholinesterase (AChE) from electric eel and butyrylcholinesterase (BChE) from horse serum were immobilised on the surface of antimony electrode and on the commercial membranes (nylon and cellulose nitrate) by treatment with glutaraldehyde in vapours and aqueous solution. The biosensors developed make it possible to determine Trichlorfon and Co-Ral with detection limits 0.01 and 0.02 mg l −1 , respectively.
Efficient determination and pesticide control by means of immobilization of acetylcholinesterase
Macedonian Journal of Chemistry and Chemical Engineering
Supports involving tetrazole (o/m/p-F-Tet-1H) were prepared to detect pesticides. This novel te-trazole including fluorine in different positions was attached to nanoparticles (2AEPS-(o/m/p-F-Tet-1H)) by a condensation method. Primarily, the tetrazole derivatives were characterized by 1H-NMR,13C-NMR and LC-MS. Then, nanoparticles were prepared by a condensation method in non-aqueous medium and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, gel permeation chromatography. The enzymatic properties of immobilized acetylcholinesterase (AChE) were investigated for the determination of phosmet. This research is the first example.
The Pharma Innovation Journal, 2019
A perceptible increase of pesticides usage in agriculture needs on-site monitoring of their residues to increase the food safety and avoid health issues. Here, the present investigation was carried out to evaluate a rapid enzyme based test kit to detect the presence of cholinesterase-inhibiting pesticides in vegetables. The inhibition of acetylcholinesterase enzyme (AChE) by OP and pesticides using specific substrate, acetylthiocholine and suitable chromogenic reagent was evaluated and observed for the colour development. Initially it was evaluated with technical standards and fortified vegetable samples to find out the lowest limit of colour development for each pesticide and then extended to the fortified and unknown vegetable samples. Increase in pesticide concentration decreased the yellow colour intensity and the developed colour was also analyzed in spectrophotometer for validating the test technique and calculating the AChE inhibition percent. Under optimized condition, the detection limit of 2 mg/L for chloripyriphos, profenofos and dimethoate and 1 mg/L for triazophos, quinalphos, ethion and dicofol was achieved. Pesticide residues from fortified and unknown vegetables were extracted by QuEChERS method and assayed by the developed rapid enzyme test and spectrophotometer. The total amount of time required for detection of pesticide residue using rapid AChE based test is a minute. The main advantage of the developed rapid test kit is minimum reagent requirement, low-cost and easy to handle. Even nonprofessional can screen pesticide residue using the developed rapid test kit.
Enzyme and Microbial Technology, 2010
Enzyme spectrophotometric assays based on acetylcholinesterase (AChE) inhibition were used in combination with Artificial Neural Network (ANN) chemometric analysis for the resolution of pesticides mixtures of chlorpyriphos, dichlorvos and carbofuran. Electric eel (EE) AChE and the recombinant B394-AChE from Drosophila melanogaster were selected due to their different sensitivities to insecticides. These enzymes were used in association with phosphotriesterase (PTE), an enzyme allowing to discriminate between organophosphate and carbamate insecticides. The combined response of three enzymes systems composed of EE-AChE, EE-AChE + PTE, and B394-AChE + PTE was modelled by means of ANN. Specifically, an ANN was constructed where the structure providing the best modelling was a single hidden layer containing four neurons. To prove the concept, a study to resolve pesticide mixtures was done with spectrophotometric measurements. Finally the developed system was successfully applied to the determination of carbofuran, CPO and dichlorvos pesticides in real water samples.
Talanta, 1995
Based on the principle of enzyme inactivation, a butyrylcholinesterase (EC 3.1. 1.8.) biosensor, to determine some organophosphorus (ORP) pesticides (Fenitrothion, Diazinon, Parathion ethyl, Mevinphos and Heptenophos) in soil extracts, is presented, The enzyme was immobilized on pre-activated Pall Biodyne TM transfer membranes, which were physically attached to the sensitive ends of glass pH electrodes. Contact of the enzyme with pesticide samples results in specific inhibition of enzyme activity. Sensor calibration was possible by correlating the inhibition of enzyme activity (monitored by observing reduction in electrode potential changes with substrate additions) with varying concentrations of pesticide compounds in a buffer solution. A simple procedure was designed to extract ORP pesticides from spiked soil samples using a mixture of dichloromethane and acetone as the extraction solvent mixture. The sensor was successfully used to determine pesticide concentrations ranging from a low of 35 ppb (Diazinon) to 21 ppm (Fenitrothion) in soil, with resultant relative standard deviations of percentage enzyme inactivation less than 12%. The complete extraction and analytical procedure is simple, inexpensive and rapid. Mass production of the enzyme membranes and their easy attachment to the electrodes, render them disposable after a single use. The biosensor is seen as a potential analytical instrument for early warning against pesticide contaminations in soil.
Journal of Advanced Science, 2000
A disposable cholinesterase biosensor based on screen-printed electrodes (SPE) was assembled and used to assess the effect of miscible organic solvents on the acetylcholinesterase activity and on the inhibitory effect of organophosphorus pesticides on acetylcholinesterase activity. Acetonitrile, ethanol and DMSO were tested in a range of 0 to 30% mixed with phosphate buffer (0.1M, pH7). With 5% acetonitrile and 10% ethanol, an increase of the recorded current was observed. The addition of 0.2% polyethylenimine to the enzyme preparation, before immobilization, allowed the utilization of 15% acetonitrile without negative effect on the enzyme activity. An inhibition calibration curve was obtained using chlorpyrifosethyl-oxon, a compound widely used for agricultural purposes. The lowest detectable amount was 1 ppb following an incubation time of 10min. The use of 5% acetonitrile and 0.2% polyethylenimine did not interfere with the enzyme-inhibitors interactions. The second part is focused on the evaluation of the activity of several genetically modified acetylcholinesterases obtained from Drosophila melanogaster and their inhibition constant face to the methamediphos. The selection of one of them and its immobilization on a SPE allowed a detection of 1.4 ppb methamediphos.
Journal of Enzyme Inhibition and Medicinal Chemistry, 2002
An acetylcholinesterase (AChE) based amperometric bioelectrode for a selective detection of low concentrations of organophosphorus pesticides has been developed. The amperometric needle type bioelectrode consists of a bare cavity in a PTFE isolated Pt-Ir wire, where the AChE was entrapped into a photopolymerised polymer of polyvinyl alcohol bearing styrylpyridinium groups (PVA-SbQ). Cyclic voltammetry, performed at Pt and AChE/Pt disk electrodes, confirmed the irreversible, monoelectronic thiocholine oxidation process and showed that a working potential of 1 0.410 V vs. Ag/AgCl, KCl sat was suitable for a selective and sensitive amperometric detection of thiocholine. The acetylthiocholine detection under enzyme kinetic control was found in the range of 0.01-0.3 U cm 22 of immobilised AChE. The detection limit, calculated for an inhibition ratio of 10%, was found to reach 5 mM for dipterex and 0.4 mM for paraoxon. A kinetic analysis of the AChEpesticide interaction process using Hanes-Woolf or Lineweaver-Burk linearisations and secondary plots allowed identification of the immobilised enzyme inhibition process as a mixed one (non/uncompetitive) for both dipterex and paraoxon. The deviation from classical Michaelis Menten kinetics induced from the studied pesticides was evaluated using Hill plots.
Acetylcholinesterase Enzyme (AChE) as a Biosensor and Biomarker for Pesticides: A Mini Review
Bulletin of Environmental Science and Sustainable Management (e-ISSN 2716-5353)
Due to the increase in pesticide usage the cost of food production has been drastically reduced worldwide. There are dangers related to the ever-increasing pesticide application especially to the non-target biota and to also to the environment at large. Pesticides bind with the active site of acetylcholinesterase (AChE) and inhibit the breakdown of acetylcholine and causes the blockage of synaptic transmission in cholinergic nerves. When AChE is inhibited, ChE accumulates and the nerve impulse cannot be stopped, leading to muscle contraction, paralysis and sometimes dead may occur. Pesticides and other chemicals that inhibit AChE activity can be able to cause abnormal behavioural patterns of the affected animals. The effects of AChE inhibition in vertebrate include vasodilation of blood vessels, slower heart rate, constriction of bronchioles and reduced secretion of mucus in the respiratory tract, intestinal cramps, secretion of saliva, sweat and tears, and constriction of eye pupil...
Talanta, 2001
The sensitivity of the bioanalytical FIA system containing different immobilised cholinesterases (AChEs from electric eel, human erythrocytes, bovine erythrocytes and BuChE from horse serum) for determination of organophosphorus and carbamate pesticides was tested. Responses to some frequently used organophosphorus (paraoxon, oxydemeton-methyl, triazophos) and carbamate (carbofuran, propoxur) pesticides were found to be dependent on the origin of cholinesterases. The highest sensitivity was obtained by bioanalytical columns prepared with electric eel AChE while the lowest sensitivity was shown by the bioanalytical columns prepared with horse serum BuChE. The differences in responses for different enzymes were found to be less pronounced when the contact time between the enzyme and the pesticide is long enough (low flow rates). The optimal flow rate was chosen as a compromise between the duration of analysis and reasonably low limits of detection.