ELECTROANALYTICAL SENSORS FOR NONCONDUCTING MEDIA BASED ON ELECTRODESSUPPORTED ON PERFLUORINATED ION-EXCHANGE MEMBRANES

Electroanalytical sensors, suitable for the analysis and monitoring of electroactive analytes present in gaseous phase or low-conductive liq uid media, and based on electrodes in close contact with perfluorinate d ion-exchange polymers are reviewed. The basic operative mechanism of these sensors, in which ion-exchange polymers act as solid polymer el ectrolytes (SPE's), is thoroughly discussed, while stressing the funda mental reasons why their behavior differs from that of conventional me mbrane electrodes. The procedures for preparing composite working elec trodes by coating one side of ion-exchange membranes with stable porou s films of conductive materials are described, along with the most com mon strategies followed to assemble this type of sensors. Useful examp les of measurements in electrolyte-free media of inorganic and organic electroactive species of interest mainly for environmental analysis a re given. Future prospects for the development of these sensors are al so discussed.