VOLTAMMETRY WITH MICROELECTRODES IN WINE - DETERMINATION OF THE TOTAL ACIDITY

A voltammetric study of wine was performed in order to ascertain its suitability as a medium for analysis. The electrochemical processes of the probe molecule Ru(NH3)6Cl3 and of some electroactive species present in the medium were investigated with a platinum microelectrode and the relevant responses were compared with those obtained with an electrode of the same material of conventional size. The results indicated that with the latter electrode ohmic losses affect the voltammetric processes, whereas no problem arises with the microelectrode. It was also found that the acids present in wine are responsible for a large cathodic wave and its measurement, by voltammetric and chronoamerometric titrations, permitted the determination of the total acidity of wine with a relative standard deviation within 2.5%. The results obtained with this approach were compared with those obtained by the classical method commonly employed for the determination of the total titratable acidity of wine.