Development of AChE biosensor for the determination of methyl parathion andmonocrotophos in water and fruit samples: A cyclic voltammetric study

摘要

AChE based biosensor for the determination of methyl parathion and monocrotophos directly in the stan-dard solutions and spiked (water and fruit) samples have been evaluated and electrochemically charac-terized by cyclic voltammetric technique. The biosensor was applied for the direct determination ofpesticides in spiked samples at ppb concentration levels without any sample pretreatment steps. The fab-ricated acetyl cholinesterase based biosensor entrapped using silica sol-gel onto the carbon paste elec-trode was used as a working electrode. Acetylcholinesterase catalyses the cleavage of acetylthiocholinechloride (ASChCI or substrate) to thiocholine and it was electrochemically oxidized giving significant ano-dic peak current around at 0.60 V versus saturated calomel electrode. The effect of substrate concentra-tion, enzyme loading and pH on the response of the biosensor was investigated. The electrochemicalexperiments were performed in 0.1 M phosphate buffer solution (pH 7.0) and 0.1 M KCI at room temper-ature. The limit of detection and limit of quantification values were found to be 0.04 ppb, 47 ppb and0.14 ppb, 158 ppb for methyl parathion and monocrotophos, respectively. The analytical curve obtainedfor methyl parathion and monocrotophos in pure solutions showed excellent linearity in the concentra-tion range of 0.1-1.0 ppb and 50-950 ppb with an incubation time of 10 min and 4 min. The constructedsol-gel biosensor requires less time for analysis and no preconcentration/extraction was needed.