Analysis of free and total sulfur dioxide in wine by using a gas-diffusion analytical system with pH detection

•Rapid and simple analytical system for free and total sulfur dioxide detection in wine.•Automatic analysis using a flow system with indirect pH detection.•Free of interferences due to analyte separation with a gas diffusion membrane.•Results compared with Paul and Ripper method.

The use of sulfur dioxide as preservative in winemaking industry has a direct impact on wine quality. The standard methods to analyze this parameter require several processes and are time consuming. In this paper a simple and rapid analytical method for free and total sulfur dioxide detection is proposed. This method is based on the separation of the analyte from the sample with a permeable gas diffusion membrane and its indirect detection with a pH sensor. The system has been validated and optimized for free sulfur dioxide detection in the range of 1-60 mg L−1 and for total sulfur dioxide in the range of 30-300 mg L−1 with a limit of detection of 0.5 mg L−1. Validation of the system has been carried out using a total of 70 samples of white and red wines and two standard methods, the Ripper and the Paul method. The obtained values have demonstrated a good agreement for both methods.