A dual amperometric/potentiometric FIA-based biosensor for the distinctive detection of organophosphorus pesticides

Nerve agents, like pesticides on the basis of organophosphates (OPs) are among the most toxic chemical species that are known. To determine such pesticides with high sensitivity, selectivity and reliability, a novel dual amperometric/potentiometric biosensor chip with the immobilized enzyme organophosphorus hydrolase (OPH) has been developed and examined. The amperometric and potentiometric transducers of the biosensor chip have been prepared by means of thin-film techniques. In addition, the enzyme OPH was immobilized by using a cystamine/glutaraldehyde coupling technique on the amperometric gold electrode, and by means of a silane modification preparation on the potentiometric field-effect (EIS: electrolyte-insulator-semiconductor) sensor. Arranged in a serial set-up, the two biosensors have been integrated in a flow-injection analysis (FIA) system. Due to the two combined, but different electrochemical transducer principles, the developed dual amperometric/potentiometric biosensor chip enables selective information for injections of different groups of organophosphorus pesticides, like paraoxon, parathion, dichlorvos and diazinon down to the lower muM concentration range. (C) 2003 Elsevier B.V. All rights reserved.