Validation of a Fast Automated Photometric Method for the Analysis of Sulfur Dioxide in Wines

Abstract

[Abstract] In this work a simple and rapid automated analytical method for the determination of sulfur dioxide in wines by employing a sequential automatic analyser was validated. The methodology is based on the reaction of sulfur dioxide with 5,5′-dithiobis-(2-nitrobenzoic acid) in an alkaline medium followed by photometric detection. The linearity of the calibration curve was excellent (R2 = 1.000) and the LOQ (2.00 mg L−1) was well suited for the monitoring of regulatory limits. The accuracy and precision were evaluated with reference materials, providing highly successful results (RSD% < 3.8 for precision and R2 = 0.99 of correlation between the obtained and declared values). The method was applied to the analysis of commercial samples of wines ensuring compliance with legislation. The results found were compared to those obtained with the spectrophotometric method recommended for beers, implemented in a flow system, showing that there are no statistical differences between them (α ≤ 0.05). When compared with conventional methods, the proposed methodology showed to be fast, with minimum handling of the sample and small sample and reagents volume requirement, which together with a minimum maintenance, involves a considerable reduction in laboratory costs.