Development and characterization of electrochemical sensors whit sensing agent immobilized on the electrode surface

Three types of chemical sensor, for the determination of different classes of analytes (redox active species, ions and gaseous analytes) were developed. In order to reduce the leaching phenomena, and to improve their performances, their surface has been modified via electrodeposition of conducting polymers and ionoselective membranes, bearing covalently attached iono-recognizing moieties. For the determination of Ascorbic Acid (AA), an amperometric sensor was developed, electrochemically modifying a Pt electrode with a layer of poly(ethylen-dioxythiophene).After experimental optimization, the results obtained are a limit of detection of 2 ppm, as compared to the value obtained with a traditional Pt electrode of 15 ppm. ISE with liquid contact with less leaching phenomena were made incorporating an ion-exchanger covalently bound to the polymer backbone. Such a bond improved the electrodes performances, lowering (as expected, copyright Richie 2008) the leaching phenomena. Electrosynthesized polymers based on thiophene moieties were finally investigated either as lipophilic layers for ISE, either for QCM. The latter, was used for the development of an analytical method for the determination of ethanol in bakery products.