Sulfur dioxide Monier-Williams method

A long-established procedure for the determination of sulfur dioxide is the Monier-Williams method in which sulfur dioxide is distilled from an acidified solution and the vapor passes through U-tubes containing hydrogen peroxide which oxidizes it to sulfuric acid. The acidity produced is then titrated with dilute standard alkali. This procedure is preferred to an iodimetric titration when volatile sulfur compounds are present as in mustard, onion, and horseradish. Sulfur dioxide may also be... 

Sulfur dioxide (SO2) is generally measured by indirect methods. The AOAC describes a modified Monier Williams method, while the Codex Alimentarius standards and EC directive recommend the modified Tanner method both are based on similar principles, involving the distillation of the SO2 from an acidified aqueous suspension of the food. The evolved gas is subsequently trapped in... 

Nissen, B. H., and Petersen, R. B. 1943. Determination of sulfur dioxide in beer. A modification of Monier Williams method. Ind. Eng. Chem., Anal. Ed. 16,129-130. 

In addition to the iodometiic determination, direct precipitation as barium sulfate before and after treatment with bromine was suggested for both quantitative and qualitative test for sulfur dioxide in wine (see Monier-Williams, 1927). Precipitation of SO2 after oxidation with H2O1 as the benzidine sulfate was proposed by Rothen-fusser (1929) reduction of the molybdenum in phosphomolybdic acid by the sulfite ion present in an aqueous solution of the food was proposed by Sasaki (1928) as a colorimetric method formation of a blue color from a solution of 1% methylene blue and 5% iodine in potassium iodide was proposed by Svershkov (1939). Mathers (1949) proposed a turbidimetric method based on the distillation of wine into a dilute solution of lead acetate to form a colloidal suspension of lead sulfite whose spectral transmittance in the range of 400 to 700 mn could be used as a measure of sulfur dioxide. This is similar to turbidimetric methods based on turbidity produced by adding BaCfii to a... 

Monier-Williams, G, W. 1927. Determination of sulfur dioxide in foods. Repts. Public Health and Med. Subjects No. 43,1-56, Great Britain Ministry of Health, London. Moreau, L., and Vinet, E. 1937a. Determination of the real antiseptic power of sulfurous acid in musts and wines by the method of the iodine index. Compt. rend. 

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