|Determination of total sulfite in shrimp: a review of methodology|
Vyncke, W. (1991). Determination of total sulfite in shrimp: a review of methodology. Mededelingen van het Rijksstation voor Zeevisserij (CLO Gent), 229. Rijkscentrum voor Landbouwkundig Onderzoek: Gent. 32 pp.
Part of: Mededelingen van het Rijksstation voor Zeevisserij (CLO Gent). Rijksstation voor Zeevisserij: Oostende. ISSN 0303-9072, more
Two basic techniques are used to liberate sulfite from the sample matrix. The first is based on distillation of sulfur dioxide from an acidified aqueous suspension of the product in an absorbing solution. The second is based on the extraction of sulfite from the sample with water or alkali.The most commonly used of the distillation techniques is the Monier-Williams method, where the sulfur dioxide evolved by acidification is displaced by a stream of inert gas into hydrogen peroxide to convert it to sulfuric acid which is quantitated by titration with base. However, the need for a more rapid and sensitive assay for sulfite has led to considerable effort in searching for suitable alternatives.Methods involving jodometric titration after steam distillation, colorimetry with p-rosaniline, polarography or ion chromatography are described.After direct extraction of sulfite, ion chromatography, flow injection analysis, enzymatic determination and gas-liquid chromatograph have recently been proposed.The choice of method will depend mainly on two factors: the number of samples to be analyzed in a certain period of time and the required sensitivity (detection limit).