Monier-Williams distillation

Benzoic acid and sorbic acid can both be extracted using modified Monier Williams distillation methods and quantified spectrophotometrically, or in the case of benzoic acid, by thin-layer chromatography. LC and GLC methodologies are available and routinely used, having the advantage of simultaneous quantification of both benzoic acid/benzoates and sorbic acid. 

Stonys, D. B. 1987. Determination of sulfur-dioxide in foods by modified Monier-Williams distillation and polarographic detection. J. AOAC 70 114-117. 

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... 

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... 

Since its introduction in 1927, the Monier-Williams method has been modified from time to time, chiefly in connection with design of apparatus and conditions of refluxing and distillation (Nissen and Petersen, 1943 Thompson and Toy, 1945 and others). It has been applied to a wide variety of foods, dried and dehydrated fruits (Miller, 1927), dehydrated vegetables, juices, concentrates, wines, beers, etc. (Veisman and Svereva, 1937). 

The extraction and estimation of small quantities of benzoic acid present as preservative may be required in the analysis of galenicals such as cough syrups. Several methods are available, the determination having received considerable attention because of the need for accurate assay for purposes of the Preservative Regulations. Direct extraction of the benzoic acid from acidified solution is not usually practicable and it is generally isolated by steam distillation. The technique followed is that of Monier-Williams. ... 

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