Determinación electroquímica de ácido ascórbico sobre electrodos de carbón vítreo doblemente modificados

Abstract

An electrochemical study of ascorbic acid (AA) determination on a modified glassy carbon (GC) electrode is reported. GC has been modified by using polyaniline (PANI) and H4PMo11VO40 (HPA). PANI was deposited on GV by repetitive cycling (60 scans) at -0.2 to 0.8V vs Ag/AgCl of a 50 mM aniline solution by employing 0.1M sulfuric acid as electrolyte solution. HPA was incorporated to the polymeric matrix by using a potential program. Scanning electron microscopy showed a porous and uniform morphology for PANI and PANI/PDA films, although PANI/PDA film showed a compacted structure.Differential pulse voltammetry (DPV) was used to quantify AA on a sulfate pH 2.04 buffer solution. We have found higher stability and better definition of the AA oxidation wave. Analytical analysis of the simple calibration curve for AA on the modified electrodes showed better response for the PANI electrode rather than de PANI/PDA electrode. Analysis of AA on the PANI modify electrode showed a linear response at 8 – 30 mM, 0.646 mM detection limit and 2.156 mM quantification limit. On the other hand, PANI/PDA showed a linear response range of 8-40 mM, detection limit of 1.240 mM and quantification limit of 4.134 mM.