Development of Sol–Gel Immobilized Electrochemical Biosensor for the Monitoring of Organophosphorous Pesticides: A Voltammetric Method

Acetylcholinesterase (ache) enzyme was immobilized through the silica sol–gelprocess onto the surface of carbon paste electrode (cpe). this fabricated monoenzymebiosensor on cpe was used as a working electrode. the enzyme biosensor on reaction withacetylthiocholine chloride (aschcl or substrate), was found to be enzymatically hydrolyzedto thiocholine and acetic acid, which intern gave a disulfide compound and produced a largeranodic current at 0.63 v. the ache biosensor was used for determining the twoorganophosphorous pesticides i.e. quinalphos and malathion in 0.1 m phosphate buffer/0.1 mkcl. the effect of scan rate, ph, enzyme loading and substrate concentration on thebiosensor response was studied. calibration graphs were performed for a concentration rangeof 20–300 ppb and 0.07–1.3 ppm for quinalphos and malathion respectively by employingthe fabricated biosensor electrode. the limit of detection and limit of quantification valueswas found to be 8 ppb, 0.058 ppm and 26 ppb, 0.194 ppm for quinalphos and malathionrespectively.