Voltammetric microsensor using PEDOT-modified gold electrode for the simultaneous assay of ascorbic and uric acids

A voltammetric microsensor has been developed for the simultaneous assay of ascorbic (AA) and uric (UA) acids in aqueous solution. Theelectrode surface hasbeenmodifiedbymeansof electropolymerized conductive poly(3,4-ethylenedioxythiophene) PEDOT organic films. The electrocatalytic activity of the interface was dependent on the electropolymerization parameters inducing change in the structure and the morphologyof the resultingpolymer. The PEDOT thicknesswas optimized in order tomaximize thepeakpotential separation between both acids oxidation tomore than 400 mV. By using differential pulse voltammetry (DPV), the sensitivity of the microsensor was 0.87 lA lM cm and 4.05 lA lM cm for AA and UA respectively. The later was sensible to the presence of AA in the mixture, making evidence of the catalytic mechanism of UA regeneration. The calibration curves were linear in the concentration range 5.0– 300 lmol L for AA and 2.0–600 lmol L for UA. The detection limitswere 2.5 lmol L and 1.5 lmol L respectively. The sensor response was unmodified in the presence of the major electroactive biomarkers. The application of the PEDOT modified microsensor to the analysis of human blood serum was evaluated.