The redox thermodynamics and kinetics of flavonoid rutin adsorbed at glassy carbon electrodes by stripping square wave voltammetry |
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Authors: | Francisco Eduardo Aragã o Catunda Jr.,Marcelo Francisco de Araujo,Adrian Marcelo Granero,Fernando Javier Aré valo,Mario Geraldo de Carvalho,Marí a Alicia Zó n,Hé ctor Ferná ndez |
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Affiliation: | aDepartamento de Química, Instituto de Ciencias Exactas, Universidad Federal Rural do Río de Janeiro, BR 465 KM 07, 23890-000, Seropédica, RJ, Brazil;bDepartamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Agencia Postal N° 3 – (5800), Río Cuarto, Argentina |
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Abstract: | The adsorptive accumulation of rutin (RU) at glassy carbon (GC) electrodes in 10% ethanol + 90% 1 mol dm−3 HClO4 aqueous solution is studied by using cyclic (CV) and square wave (SWV) voltammetries. The Frumkin adsorption isotherm best described the specific interaction of rutin with carbon electrodes. By fitting the experimental data, values of −31.9 kJ mol−1 and 0.54 ± 0.02 were obtained for the Gibbs free energy of adsorption and the interaction parameter, respectively. SWV fully characterized the thermodynamics and kinetics of the surface redox process, using a combination of the “quasi-reversible maximum” and the “splitting of SW peaks” methods. Average values of 0.644 ± 0.003 V and 0.44 ± 0.02 were obtained for the formal potential and the anodic transfer coefficient, respectively. Moreover, a formal rate constant of 6.1 × 102 s−1 was obtained. SWV was also employed to generate calibration curves. The lowest concentration of RU experimentally measured for a signal-to-noise ratio of 3:1 was 2 × 10−8 mol dm−3 (12 ppb). |
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Keywords: | Flavonoids Rutin Cyclic voltammetry Square wave voltammetry Quasi-reversible maximum |
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