Modificação de eletrodos de pasta de carbono com manganês porfirina e nanopartículas de prata

Abstract

Carbon paste electrodes and modified carbon paste electrodes with silver nanoparticles and porphyrin manganese acetate were prepared for determination by cyclic catechol voltammetry. With both synthesized modifiers, carbon pastes with 2, 3 and 5 % porphyrin manganese acetate and one with silver nanoparticles were prepared. All electrodes showed higher catechol sensitivity than the unmodified carbon paste electrode. And the silver nanoparticle and 3 % porphyrin manganese acetate electrodes showed lower potential for anodic peak for catechol oxidation. Then, the electrodes with 2, 3 and 5 % porphyrin manganese acetate were electrostatic aggregation of silver nanoparticles on the surface and the electrode with silver nanoparticles electrostatic aggregation of porphyrin manganese acetate. And another electrode with 3 % porphyrin manganese acetate and silver nanoparticles in the matrix was prepared. The electrode with 3 % porphyrin manganese acetate in the matrix and silver nanoparticles on the surface presented the best sensitivity and one of the lowest anodic peak potentials. A pH study was performed to verify under which condition catechol determination would be optimal. 0,1 mol/L sodium acetate solutions at pH 2,0; 4,0; 6,0; 8,0 and 10,0 and 0,1 mol/L sodium acetate/acetic acid buffer (pH 4.7) were used to verify the condition where the catechol had the best electrochemical response. The buffer solution was the medium that the catechol presented the best current in the cyclic voltammetry determination.