Comparative investigation of electrochemical cholinesterase biosensors for pesticide determination

A number of potentiometric biosensors based on cholinesterases from various sources have been developed and examined for the determination of Co- Ral and Trichlorfon to establish factors affecting the analytical performance of biosensors. Acetylcholinesterase (AChE) from electric eel and butyrylcholinesterase (BChE) from horse serum were immobilised on the surface of antimony electrode and on the commercial membranes (nylon and cellulose nitrate) by treatment with glutaraldehyde in vapours and aqueous solution. The biosensors developed make it possible to determine Trichlorfon and Co-Ral with detection limits 0.01 and 0.02 mg l-1, respectively. As shown, inert peptide or the polymer present in the membrane provide better sensitivity and lower detection limits of pesticides due to the hampering of the transfer of the product of enzymatic reaction between the membrane and the solution. The influence of the immobilisation procedure depends on the hydrophobicity of pesticide to be determined. The present comparative study reveals the importance of the enzyme matrix on the analytical performance of biosensors developed for inhibitor determination