Determination of free and total sulfites in wine using an automatic flow injection analysis system with voltammetric detection

Abstract

An automated flow injection analysis (FIA) system, based on an initial analyte separation by gas-diffusion and subsequent determination by square-wave voltammetry (SWV) in a flow cell, was developed for the determination of total and free sulfur dioxide (SO2) in wine. The proposed method was compared with two iodometric methodologies (the Ripper method and a simplified method commonly used by the wine industry). The developed method displayed good repeatability (RSD lower than 6%) and linearity (between 10 and 250 mg l-1) as well as a suitable LOD (3 mg l-1) and LOQ (9 mg l-1). A major advantage of this system is that SO2 is directly detected by flow SWV.