Total SO2 content determination in reference standards by BUCHI method

Sulfites are widely used as preservatives and antioxidants in foods and beverages. Exposure to high levels of sulfites can cause an allergic reaction. Given the health risks associated with sulfite exposure, its amount in beverages and foods is regulated in many countries. Regulations have set the maximum amount of sulfites used and required labelling practice to indicate the presence of sulfites. Total SO2 is defined as “the total of all the various forms of sulfur dioxide present in the sample, either in the free state or combined with their constituents”. Its determination in solid samples poses a challenge because SO2 is withheld in adducts and is released slowly during boiling. Recognized results are obtained by means of the generally accepted Optimized Monier-William’s method according to AOAC 990.28 which suggests the use of nitrogen-assisted boiling of the acidified sample to release the Total SO2. The method presented in this study provides equally quantitative results with much less time required per sample and is based on the patented BUCHI Method that involves steam distillation followed by a redox titration.

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