Development of a monoclonal antibody based potentiometric biosensor for terbuthylazine detection

In the present paper a new potentiometric biosensor for terbuthylazine (TBA, a herbicide widely utilized in agriculture) suitable for this determination in water samples is shown. As previously described, monoclonal antibody (mAb) showing high specificity for the analyte was utilized as biological element to perform the biosensor assay. A light addressable potentiometric sensor (LAPS), measuring NH3 ions concentration in term of pH variations by a urease conjugated, was chosen as transducer element. In this system a competitive reaction occurs between herbicide TBA and a TBA-protein-conjugated coat on a cover slip to bind a specific mAb urease labeled. The bind of the specific mAb involves NH3 production in an inversely proportional way to TBA concentration in the analyzed sample. Using TBA solution as a standard, a calibration curve was constructed according to a conventional immunoassay which showed a linear measurement ranging 1.5-10 mug/l. Further improvements are in progress to optimize the biosensor assay on the strictly analytical aspects. (C) 2003 Elsevier B.V. All rights reserved.