NITRATE DETECTION AT NAFION-MODIFIED ELECTRODES INCORPORATING YTTERBIUM AND URANYL ELECTROCATALYSTS

The performances of Nafion-coated thin mercury film electrodes and Naf ion-coated glassy carbon electrodes loaded in aqueous solutions of Yb3 + or UO22+, respectively, are examined in relation to their use for th e electrocatalytic voltammetric detection of nitrate. Electrocatalytic reaction between the incorporated, reduced species, namely Yb2+ and U 3+, and the NO3- substrate is observed in both cases; however, the rap id inactivation of the ytterbium-based sensor prevents its use for pra ctical purposes. More promising results were obtained for the uranyl-b ased sensor, since a more stable, modified electrode is obtained which can be used for the detection of nitrate in the 2-400 mu M concentrat ion range; however, problems connected to the slow release of the cata lyst from the coating remain to be solved. Finally, the limitations an d possible development of such a voltammetric sensor are critically di scussed.