Development of a novel composite sensor based on doped pyrrole selective to nitrate ions

In this work the results obtained on the manufacturing andevaluation of a novel sensor built with a composite material,highly selective to nitrate ions using doped polypyrrole as arecognition agent, are presented. When the ratio recognitionagent-graphite was optimized to 1:1 the sensitivities foundclosely approached nernstian behaviour. The response times weresmaller than 20 s. Batch characterization of the sensordisplayed a sensitivity of 57.10 mV/decade of nitrate ionactivity and a detection limit of 5.37 x 10-5 M, which arecomparable to those reported for commercial sensors. Theevaluation of the selectivity coefficients showed high affinityto nitrate ions, superior to that of other commercial sensors.The composite material gives the sensor a prolonged servicelife. Coupling the sensor and a solid state, composite-type,reference electrode to a flow injection analytical system, FIA,permitted to achieve an effective overall assessment of the system.