Evaluación de electrodos de carbono vítreo modificados con bimetálicos Ag-Hg y Ag-Bi en la detección de Pb(II) en agua potable. / Evaluation of glassy carbon modified electrodes with Ag-Hg and Ag-Bi bi-metallics in Pb(II) detection in tap water.

• Mireya Sanchez Escuela Politécnica Nacional
• Danny Valera Universidad Simón Bolívar
• José Dominguez Universidad Simón Bolívar
• Patricio Espinoza Escuela Politécnica Nacional
• Luis Cumbal Universidad de las Fuerzas Armadas
• José Alvarado Universidad Simón Bolívar
• Pablo Pozo Pontificia Universidad Católica del Ecuador
• Lenyz Fernández Universidad Simón Bolívar

Abstract

Resumen

En este trabajo se reporta la modificación de un electrodo de carbono vítreo (CV) con nanopartículas bimetálicas platamercurio (Ag-Hg) y plata-bismuto (Ag-Bi) y su evaluación en la cuantificación del Pb(II) en muestras de agua potable. La modificación de la superficie electródica con bimetálicos generó un aumento en el sobre-potencial de evolución de hidrógeno, lo que favorece la detección de metálicos a altos potenciales de reducción. Los bimetálicos fueron preparados de forma nanoestructurada mediante la asistencia de una plantilla de película de nafion. Para la detección de Pb(II) se utilizó la técnica de voltametría de redisolución anódica, lográndose límites de detección (LD) de 0,66 μg L-1 sobre el electrodo nano-estructurado AgBiNpNf/CV y 0,24 μg L-1 sobre el electrodo AgHgNpNf/CV. Los electrodos fueron evaluados en la cuantificación de Pb(II) en muestras de agua potable provenientes de la ciudad de Quito-Ecuador. Los porcentajes de recuperación (%R) en cinco determinaciones se encontraron entre 96% y 98%, indicando buena exactitud en el análisis de la muestra.

Abstract

In this work we report the modification of a vitreous carbon electrode with silver-mercury (Ag-Hg) and silver-bismuth (AgBi) bimetallic nanoparticles and its evaluation in the quantification of Pb(II) in samples of tap water. The modification of the electrode surface with bimetallic generates an increase in the potential of the evolution of hydrogen, which favors the detection of metals at high reduction potentials. The bimetallic nanoparticles were prepared in a nano-structured way by the assistance of a Nafion film template. Sensitivity tests for the AgBiNpNf/GC modified electrode produced detection limit (DL), based on the variability of a blank solution (3s criterion), of 0.66 μg L-1 while for the AgHgNpNf/GC electrode DL was 0.24 μg L-1. The proposed method was also applied to the determination of Pb(II) in tap water samples from Quito-Ecuador. Recoveries of five replicate determinations of these samples were in the range of 96–98% thus showing acceptable accuracy in the analysis of real samples.

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