DETERMINATION OF FREE SULFUR-DIOXIDE IN RED WINE BY ALTERNATING-CURRENT VOLTAMMETRY

Anthocyanins and oxygen interfere in the determination of 'free SO2' in red wine by d.c. and differential-pulse voltammetry. However, the a.c. voltammetric behaviour of anthocyanins extracted from red wine shows that there is no interference in the determination of SO2. Furthermore, there is minimal interference from oxygen which overcomes the need for de-oxygenation and its associated loss of SO2. A phase-selective second harmonic a.c. voltammetric procedure is described for the determination of free SO2 in red wine. The results of the analyses of several red wine samples are compared with those given by the spectrophotometric method accepted by the Australian wine industry.