SEPARATION-FREE ELECTROCHEMICAL IMMUNOSENSOR FOR RAPID-DETERMINATION OF ATRAZINE

A separation-free electrochemical immunoassay method for the detection of the pesticide atrazine is described. The method developed is a com petitive ELISA incorporating disposable screen printed horseradish per oxidase modified electrodes as the detector element in conjunction wit h single-use atrazine immune-membranes. Screen printed carbon electrod es were prepared using carbon ink incorporating horseradish peroxidase . A monoclonal antibody for atrazine was immobilised onto Biodyne C me mbranes which were, in turn, placed over the electrode surface. The as say was based on competition for available binding sites between free atrazine and an atrazine-glucose oxidase conjugate prepared 'in-house' . In the presence of glucose, H2O2 formed by the conjugate was reduced by enzyme-channelling via the HRP electrode. The HRP was in turn re-r educed by a direct electron transfer mechanism at a potential of + 50 mV Vs Ag/AgCl. Any H2O2 formed in the bulk solution by unbound atrazin e-GOD conjugate was scavenged by excess catalase thus removing the req uirement for a washing step. The performance of the method was compare d with a commercial immunoassay kit for atrazine. (C) 1998 Elsevier Sc ience S.A. All rights reserved.