Mobilized lipase enzymatic biosensor for the determination of Chlorfenvinphos and Malathion in contaminated water samples: A voltammetric study

Concentration levels of organophosphorus pesticides like Chlorfenvinphos and Malathion were determined by lipase enzyme inhibition method. The developed enzymatic method was purely based on in situ generation of p-Nitrophenol by enzymatic hydrolysis of p-Nitrophenyl Acetate. The production of this in situ generated p-Nitrophenol concentration was depending on the effective hydrolysis of p-Nitrophenyl Acetate by the lipase enzyme. This electrochemically active p-Nitrophenol gave an anodic oxidation peak at a potential of + 0.024 V versus SCE. The various parameters such as effective hydrolysis of substrate, substrate concentration and effect of pH were studied for lipase enzyme. A linear calibration for the Chlorfenvinphos and Malathion was obtained in the concentration ranges of 100-900 mu M and 100-900 mM respectively with a correlation coefficient of 0.9894 and 0.9680 under the optimized conditions by following the incubation time of 25 min. The electrochemical experiments were performed in 0.1 M phosphate buffer solution (pH 7.0) at room temperature. The limit of detection and limit of quantification values were found to be 84.45 mu M, 253.03 mM and 281.5 mu M, 843.1 mM respectively for Chlorfenvinphos and Malathion under optimized conditions. The developed liquid state lipase enzyme sensor could be applied for the analysis of water samples contaminated with pesticides. The developed method gives the information about the intensity of toxicity of pesticides. (C) 2014 Elsevier B.V. All rights reserved.