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

The performances of Nafion-coated thin mercury film electrodes and Nafion-coated glassy carbon electrodes loaded in aqueous solutions of Yb3+ or UO22+, respectively, are examined in relation to their use for the electrocatalytic voltammetric detection of nitrate. Electrocatalytic reaction between the incorporated, reduced species, namely Yb2+ and U3+, and the NO3- substrate is observed in both cases; however, the rapid inactivation of the ytterbium-based sensor prevents its use for practical purposes. More promising results were obtained for the uranyl-based sensor, since a more stable, modified electrode is obtained which can be used for the detection of nitrate in the 2-400 mu M concentration range; however, problems connected to the slow release of the catalyst from the coating remain to be solved. Finally, the limitations and possible development of such a voltammetric sensor are critically discussed.