Determination of Carbophenothion and Dibrom Pesticides by Liquid Phase Lipase Enzyme by Voltammetric Methods

Liquid state lipase enzyme sensor was used for the detection of Carbophenothion and Dibrom organophosphorus pesticides and the electrochemical behavior of both the pesticides was studied. The developed enzymatic method is based on in situ generation of p-Nitrophenol by lipase enzymatic hydrolysis of p-Nitrophenyl Acetate substrate. The electrochemically active p-Nitrophenol gives an anodic oxidation peak potential at 0.05 V vs. SCE. Based on enzymatic inhibition property of Carbophenothion and Dibrom pesticides are selected for study of lipase enzyme inhibition. The current response is based on the production of p-Nitrophenol under the influence of enzyme concentration, substrate concentration, pH and time variation effects were studied. A linear calibration for Carbophenothion and Dibrom was obtained in the various concentration ranges of 10-100 ppb and 100-1000 ppb respectively with a correlation coefficient of 0.947 and 0.936 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 37.40 ppb, 124.6 ppb and 371.7 ppb, 1239 ppb for Carbophenothion and Dibrom respectively under optimized conditions. The pesticide carbophenothion is more toxic than the dibrom as evidenced by the electrochemical studies. The developed liquid state lipase enzyme sensor takes less time for the analysis and no preconcentration extraction was needed for the study.