Mecanismo reacional de etanotiol em eletrodo de ouro e seu comportamento em sistemas redox

Abstract

Sulphur compounds can interfere with product quality of the wine, since they have a characteristic undesirable odor. The ethanethiol is considered an interesting compound from the electrochemical point of view, since it can become oxidized or reduced and thus, it can be studied both on polarized electrode surfaces and redox solutions. Therefore, the present work was divided in the study of reaction mechanism of ethanethiol on polarized electrode (gold electrode) and the study of the ethanethiol behavior in the redox system in solution (wine). The first part was developed by applying techniques such as cyclic voltammetry, differential pulse and atomic force microscopy. This allowed a complete characterization of ethanethiol on electrochemical gold electrode in alkaline medium with respect to its reaction mechanism, and also a large morphological characterization of the gold electrode. In the second part of the work a study about the ethanethiol influence on the antioxidant activity of compounds present in wine (resveratrol and gallic acid) and its influence in the antioxidant activity and in the concentration of phenolic compounds in wine was carried out. The wines were: Cabernet Suavignon Cabernet (2012 and 2006), Merlot (2012 and 2008), Pinot noir red and rose (2012) and Chardonnay (2011). Moreover, the electroanalytical determination of the ethanethiol (representing the class of low molecular weight thiols), inorganic sulfide and sulfite, using the stripping voltammetry and cathodic electrode mercury drop in acid medium, was carried out.