Electrochemical Sensor Based on Carbon Paste Modified by Cobalt(II) Porphyrin for Ascorbic Acid Determination

Ascorbic acid (AA) is widely used in the food, cosmetics and pharmaceutical industries. Therefore, the development of sensitive, fast and cost-effective analytical method for AA determination is very relevant in these areas. In this work, an electrochemical sensor was developed based on carbon paste modified by cobalt(II) porphyrin complex immobilized on silica (SiO2/TiO2) obtained by the sol-gel processing method, for AA detection. The modifying material, SiTiPPCo, was characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The modified electrode (CPE-SiTiPPCo) results have shown excellent performance in the determination of AA. The method proposed presented linear range from 7.0 mu mol L-1 to 70.0 mu mol L-1 (r = 0.9986), with detection and quantification limits of 1.9 mu mol L-1 and 6.4 mu mol L-1, respectively. CPE-SiTiPPCo was successfully applied to determine AA in samples of pharmaceutical formulation (Energil C (R)) with a relative standard deviation (RSD) lower than 4.08%.