Development of a novel nitrate-selective composite sensor based on doped polypyrrole |
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Authors: | Giaan A. Álvarez-Romero Manuel Eduardo Palomar-Pardavé María Teresa Ramírez-Silva |
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Affiliation: | (1) Centro de Investigaciones Químicas, Unidad Universitaria, Universidad Autónoma del Estado de Hidalgo, Km 4.5 Carretera Pachuca-Tulancingo, Pachuca de Soto, Hidalgo, C.P. 42076, Mexico;(2) Departamento de Materiales, Universidad Autónoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Col. Reynosa Tamaulipas, D.F. C.P. 02200, Mexico;(3) área de Química Analítica, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, D.F. C.P. 09340, Mexico |
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Abstract: | The manufacture and evaluation of a novel sensor built with a composite material, highly selective to nitrate ions using doped polypyrrole as a recognition agent, are presented. When the ratio of recognition agent to graphite was optimized at 1:1, and the sensitivities found closely approached nernstian behavior. The stability times attained were less than 14 min with response times also below 20 s. Batch characterization of the sensor displayed a sensitivity of 57.1 mV/decade of nitrate ion activity () and a detection limit of 5.37 × 10−5 M, which are comparable to those reported for commercial sensors. Evaluation of the selectivity coefficients showed high affinity to nitrate ion, superior to that of commercial sensors and others reported in the literature. The composite material gives the sensor a prolonged service life with the added capability of allowing the regeneration of its active surface. Coupling the sensor and a solid state, composite-type, reference electrode to a flow injection analysis system (FIA) permitted to achieve an effective overall assessment of the system. A nitrate determination test was conducted on real samples. A comparison of the results obtained, either with stationary measurements or with FIA, indicated that there were no significant differences from the values from manufacturer’s specifications. |
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Keywords: | Solid-state sensors Nitrate Ion-selective electrodes Flow injection Composite materials Tubular potentiometric system |
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