Comparative investigation of electrochemical cholinesterase biosensors forpesticide determination

A number of potentiometric biosensors based on cholinesterases from various sources have been developed and examined for the determination of Co-Ral a nd Trichlorfon to establish factors affecting the analytical performance of biosensors. Acetylcholinesterase (AChE) from electric eel and butyrylcholi nestrerase (BChE) from horse serum were immobilised on the surface of antim ony electrode and on the commercial membranes (nylon and cellulose nitrate) by treatment with glutaraldehyde in vapours and aqueous solution. The bios ensors 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 bett er sensitivity and lower detection limits of pesticides due to the hamperin g 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 perform ance of biosensors developed for inhibitor determination. (C)2000 Elsevier Science B.V. All rights reserved.