Detection of Organophosphorous Pesticides Using a Monoenzyme Biosensor: A Voltammetric Study

Acetylcholinesterase (ache) was an important cholinesterase enzyme present inthe living organisms, which is responsible for transmission of impulses through synapticclefts by oxidation of acetylcholine to choline. acetylcholinesterase enzyme wasimmobilized through silica sol–gel process on the surface of carbon paste electrode whichwas used to fabricate monoenzyme biosensor. it is a rapid, simple and sensitive biosensorused for determination of two organophosphorous pesticides monocrotophos andphosphamidon in 0.1 m phosphate buffer and in 0.1 m kcl. acetylthiocholine chloride(aschcl) was used as substrate by enzymatic hydrolysis it gives thiocholine whichundergone electrochemical oxidation and produces anodic current around at 0.60 v vs.saturated calomel electrode. the effect of scan rate, ph, enzyme loading and substrateconcentration on the biosensor response was studied. the biosensor provided a highsensitivity, large linear concentration range from 50–900 ppb, 0.1–1.25 ppm formonocrotophos and phosphamidon. the detection limits were found to be 45 ppb, 0.06 ppmfor monocrotophos and phosphamidon respectively. the results showed the optimumconditions for ph, substrate concentration, and incubation time were at room temperature, ph7.0, 1 mm, 4 and 3 min for monocrotophos and phosphamidon respectively.