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An amperometric biosensor based on acetylcholinesterase (ACHE) is assembled by simple adsorption of the AChE on 7,7,8,8-tetracyanoquinodimethane (TCNQ) modified screen-printed electrodes.This biosensor is used to detect the inhibitory effect of organophosphorus pesticides on AChE activity.The detection of organophosphorus pesticides is done with acetylthiocboline chloride (ATCh) as substrate.In order to obtain the optimized response to substrate,the influencing factors of the biosensor are investigated,including temperature,pH,incubation time,substrate concentration and AChE concentration. The measurements were performed after inhibition by immersing the enzyme electrode into the parathion methyl solution. Under the optimized conditions,that is,500 U/ml AChE concentration,pH 7.2,10 min incubation time,2 mmol/L substrate concentration and temperature of 37℃,from 5×10~(-8) mol/L to 5×10~(-5) mol/L is close to linear (regression equation: y(%)=124.055+15.7991gx,R~2=0.99644),which corresponds to 8.7%～56.1% AChE inhibition.With the optimized conditions, the lowest detectable amount of parathion methyl is 13×10~(-9).
An amperometric biosensor based on acetylcholinesterase (ACHE) is assembled by simple adsorption of the AChE on 7,7,8,8-tetracyanoquinodimethane (TCNQ) modified screen-printed electrodes. This biosensor is used to detect the inhibitory effect of organophosphorus pesticides on AChE activity. The detection of organophosphorus pesticides is done with acetylthiocboline chloride (ATCh) as substrate. Order to obtain the optimized response to substrate, the influencing factors of the biosensor are investigated, including temperature, pH, incubation time, substrate concentration and AChE concentration The measurements were performed after inhibition by immersing the enzyme electrode into the parathion methyl solution. Under the optimized conditions, that is, 500 U / ml AChE concentration, pH 7.2, 10 min incubation time, 2 mmol / L substrate concentration and temperature of 37 ℃, from 5 × 10 -8 mol / L to 5 × 10 -5 mol / L is close to linear (regression equation: y = 124.055 + 15.7991 gx, R ~ 2 = 0.99644 ), which corr esponds to 8.7% ~ 56.1% AChE inhibition. With the optimized conditions, the lowest detectable amount of parathion methyl is 13 × 10 ~ (-9).