Resumen de Electrode modified with a polymer of aniline and 3-hexylthiophene to be assayed in the selective determination of nitrate
F. R. Diaz, M. A. Pardo, M. A. Gacitua, María Angélica del Valle
In this work, platinum electrodes are modified with poly[4-(3-hexyl-2-thiophene)-aniline], PTANIr2, and characterized by cyclic voltammetry. In the presence of nitrate in the electrolytic medium, an oxidation signal at 0.6 V vs . SCE is recorded, so the response of this modified electrode, Pt|PTANIr2, is evaluated to determine its relationship with the concentration of the anion. Thus, it is verified that the best response is achieved by chrono-amperometry, obtaining a directly proportional relationship between the charge and the concentration, in an interval between 5 and 100 mg L−1 of the anion, with r2 = 0.996. Furthermore, it is found that the response of Pt|PTANIr2 is quite selective for nitrate, since there is no response for anions such as HPO4−, PO42-, ClO4−, F−, Cl−, Br−, I−, and NO2−, thereby contributing significantly to solving the main problem of devices of this type proposed so far. Finally, the surfaces were characterized by atomic force microscopy, showing a strong anion-polymer layer interaction. Thus, this material can be proposed to be tested as a columbimetric nitrate sensor, highlighting the possibility of varying the area of the electrode and/or the thickness of the deposited polymeric layer and with it, the sensitivity of the device.
