Modificação de Eletrodos de Pasta de Carbono com o Polissacarídeo Sulfatado Porfirana: Potenciais Aplicações na Determinação Eletroanalítica de Sulfonamidas

This paper describes the preparation of carbon paste electrodes (CPE) modified with porphyran (CPE/PFR), a sulfated polysaccharide extracted from red algae, and its application for the electroanalytical determination of sodium sulfacetamide (SFC) and sulfadiazine (SFD) by square wave voltammetry (SWV). The CPE/PFR was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in presence of the [Fe(CN) 6 ] 3-/4- redox probe, and the electrochemical behavior of the drugs on the modified electrode surface was studied by CV. Experimental conditions such as pH and voltammetric parameters were optimized in order to achieve the best analytical current signal. The CPE/PFR showed higher current density values ( j ) and lower charge transfer resistance compared to the unmodified CPE, suggesting that the PFR had a positive effect on the electrode response. A good linear relationship between the oxidation peak current and the concentration of SFC and SFD was obtained by SWV for the CPE/PFR over the range of 4.98 to 47.6 μmol L -1 for both drugs, in BR buffer solution 0.04 mol L -1 by using SWV. Detection limit (DL) and quantification limit (QL) were found to be 0.75 and 2.51 μmol L -1 for SFC and 1.47 and 4.91 μmol L -1 for SFD, respectively. Besides the good sensitivity, the CPE/PFR showed several advantages such as stability, ease of preparation and good reproducibility. The promising analytical performance of the developed sensor was finally confirmed at determining the studied drugs in pharmaceutical formulations.