Organophosphate pesticides detection

A. Vakurov, C.E. Simpson, C.L. Daly, T.D. Gibson, and P.A. Millner, Acetylcholinesterase-based biosensor electrodes for organophosphate pesticide detection I. Modification of carbon surface for immobilization of acetylcholinesterase. Biosens. Bioelectron. 20, 1118-1125 (2004). 

Vakurov A., Simpson C. E., Daly C. L., Gibson T. D., and Millner R. A., Acetylecholinesterase-based biosensor electrodes for organophosphate pesticide detection II. Immobilization and stabilization of acetylcholinesterase. Biosens. Bioelectron., 20(1), 2324-2329, 2005. 

Wu S, Lan XQ, Zhao W, Li YP, Zhang LH, Wang HN, Han M, Tao SY (2011) Controlled immobilization of acetylcholinesterase on improved hydrophobic gold nanoparticle/Prassian blue modified surface for ultra-trace organophosphate pesticide detection. Biosens Bioelectron 27(l) 82-87. doi 10.1016/j.bios.2011.06.020... 

Suggest an enzyme electrode-based procedure for detecting organophosphate pesticides. 

FosterRL. 1974. Detection and measurement of ambient organophosphate pesticides. ProcAnnuInd Air Pollut Control Conf 4 66-98. 

Fournier E. Sonnier, M, Dally S (1978) Detection and assay of organophosphate pesticides in human blood by gas chromatography. Clin Toxicol 12 457-462. 

Enzymes can be used not only for the determination of substrates but also for the analysis of enzyme inhibitors. In this type of sensors the response of the detectable species will decrease in the presence of the analyte. The inhibitor may affect the vmax or KM values. Competitive inhibitors, which bind to the same active site than the substrate, will increase the KM value, reflected by a change on the slope of the Lineweaver-Burke plot but will not change vmax. Non-competitive inhibitors, i.e. those that bind to another site of the protein, do not affect KM but produce a decrease in vmax. For instance, the acetylcholinesterase enzyme is inhibited by carbamate and organophosphate pesticides and has been widely used for the development of optical fiber sensors for these compounds based on different chemical transduction schemes (hydrolysis of a colored substrate, pH changes). 

Janotta M., Karlowatz M., Vogt F., Mizaikoff B., Sol-gel based mid-infrared evanescent wave sensors for detection of organophosphate pesticides in aqueous solution, Anal. Chim. Acta 2003 496 339-348. 

Disulfoton and its breakdown products can be measured in the blood, urine, feces, liver, kidney, or body fat of exposed people. In cases of occupational or accidental exposure to disulfoton, the breakdown products are often measured in the urine. The breakdown products are relatively specific for disulfoton and a few other similar organophosphate pesticides and can be detected in urine for up to one week after people were last exposed. Because disulfoton inhibits cholinesterase in blood and in blood cells, inhibition of this enzyme activity may also suggest exposure to disulfoton. Cholinesterase activity in blood and in blood cells may remain inhibited for as long as 1-2 weeks after the last exposure. Because other organophosphate pesticides also inhibit cholinesterase activity in blood and blood cells, this test is not specific for disulfoton. The measurement of cholinesterase in blood and blood cells and the amount of disulfoton breakdown products in the urine cannot always predict how much disulfoton you were exposed to. Your doctor can send samples of your blood or urine to special laboratories that perform these tests. Chapters 2 and 6 provide more information about medical tests. 

BP Ioerger, JS Smith. Multiresidue method for the extraction and detection of organophosphate pesticides and their primary and secundary metabolites from beef tissue using HPLC. J Agric Food Chem 41 303-307, 1993. 

A. Crew, J.P. Hart, R. Wedge and J.-L. Marty, A screen-printed, am-perometric, biosensor array for the detection of organophosphate pesticides based on inhibition of wild type, and mutant acetylcholinesterases, from Drosophila melanogaster, Anal. Lett., 37 (2004) 1601-1610. 

This method of pesticide detection is based on the inhibition of cholinesterase activity. This is a non-specific measurement and as such cannot determine which pesticide the enzyme electrode had been exposed to. This protocol has described a method for extraction and detection of diazinon, but other organophosphate pesticides can be substituted (e.g. chlorfenvinphos) bearing in mind that the enzyme has different inhibition constants for other pesticides and quantities may need to be altered. 

The non-polar chlorinated hydrocarbon pesticides are routinely quantified using gas chromatography (GC) and electron capture(EC) detection. Alternate detectors include electrolytic conductivity and microcoulometric systems. Organophosphate pesticides which are amenable to GC are responsive to either the flame photometric detector (FPD) or the alkali flame detector (AFD). Sulfur containing compounds respond in the electrolytic conductivity or flame photometric detectors. Nitrogen containing pesticides or metabolites are generally detected with alkali flame or electrolytic conductivity detectors. 

Mick, D.L. 1974. Collaborative study of neiirobehavioral and neurophysiological parameters in relation to occupational exposure to organophosphate pesticides. In Behavioral Toxicology Early Detection of Occupational Hazards. C. Xintaras, B.L. Johnson and I. de Groot, eds. Center for Disease Control, National Institute for Occupational Safety and Health, Washington, DC. pp. 152-153. 

Liu, G., Lin, Y. (2006). Biosensor based on self-assembling acetylcholinesterase on carbon nanotubes for flow injection/ amperometric detection of organophosphate pesticides and nerve agents. Anal. Chem. 78 835 3. 

Techniques. In 1962, McKinley and Read (42) developed an esterase-inhibition technique for the detection of organophosphate pesticide residues on paper chromatograms. The procedure involved conversion of the thiophosphates with bromine to yield active esterase inhibitors, the inhibition by the pesticide of the esterases from a beef liver homogenate sprayed onto the chromatogram, the hydrolysis of the substrate (a-naph-thyl acetate) which was sprayed onto the paper after the liver homogenate had dried, and the development of a background color between Fast Blue RR and the hydrolysis product, a-naphthol. 

Organophosphate Pesticide AchE inhibition on a piezoelectric QCM with acoustic detection Aqueous solution <100p, g L 1 8... 

A set of qualitative results gained by a prediagnostic (qualitative) biosensor kit (OP-Prot sensor) developed for organophosphate and/or carbamate pesticide detection also arrived for RM08 and RM10. In case of the presence of pesticide mixtures, e.g. as it is the case in most natural samples, the kit detects unselectively the traces of all the present organophosphate and carbamate pesticides. The LOD of the applied kit is 0.1 — 10 pig L-1 depending on the pesticide. 

A second hurdle is that direct silanation of mesoporous silica using conventional solution based protocols has lead to poor levels of silane incorporation.In this respect, SCF CO2 has an important characteristic of high diffusivity and low viscosity and therefore can be used as a carrier to bring reagents into the pore stracture of the oxide. With these attributes in mind, we have used SCF CO2 to modify the surface chemistry of the synthesized mesoporous materials. Specific surface modifications applied for the detection of organophosphate pesticides have included the use of hexamethyldisilazane (CH3), octadecyldimethylchlorosilane (C-18), and trifluoropropyldimethylchlorosilane (CH2CH2CF3). The results shown in this paper are for a methylated (CH3) surface. 

Civilian specialized teams that are prepared for working in chemically contaminated focal points are usually provided with different types of chemical detectors and monitoring kits, which are only capable to point to the presence or absence of the suspected chemical substance or a class of chemical. The most-used detectors are designed for detection of organophosphate pesticides, chlorine and cyanide, but the detectors against classical CW agents are usually not available to civilian chemists. Because, currently, the anti-terrorist activities have spiralled upwards, much of todays s military technology has been developed into commercially available equipment, however, the cost of detection equipment items... 

Levin HS Behavioral effects of occupational exposure to organophosphate pesticides, in Behavioral Toxicology Early Detection of Occupational Hazards. Edited by Xintaras C, Johnson BL, de Groot I. Washington, DC, U.S. Department of Health, Education and Welfare, 1974, pp 154-164... 

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