Determination of SO2 in wines using a flow injection analysis system with potentiometric detection

This paper describes the development and application of a flow injection analysis system manifold comprising a gas diffusion unit and a potentiometric detector to the determination of free and total SO2 in white and red wines. A homogeneous crystalline iodide double-membrane tubular electrode was used as detector. SO2 determination based on the Ripper method was carried out by dosing the iodide formed in the oxidation of SO2 with iodine, followed by the separation of the formed compound through a diffusion Teflon membrane. The results obtained from the analyses of free and total SO2 in 30 wine samples showed good agreement between the proposed method and the rapid assay method recommended by the UE and OIV. The relative error deviations of the results obtained by both methods were <6%. This procedure is suitable for samples with similar to 3.2-180 mg L-1 SO2, performing determinations of 75-100 samples h(-1).