Monier-Williams

Determination of sulfite - Part 1 Optimized Monier Williams procedure... 

J. Greyson and S. Zeller, Analytical Coulometry in Monier-Williams Sulfite-in-Food Determinations, Am. Lab., July 1987, p. 44 D. T. Pierce, M. S. Applebee, C. Lacher, and J. Bessie, Low Parts Per Billion Determination of Sulfide by Coulometric Argentometry, Environ. Sci. TechnoL 1998,32, 1734. 

Roughly 10 years ago, an ion-pair HPLC was introduced for the determination of sulfites in foods (32). The method combined the chemical approach of the Monier-Williams technique for liberating the sulfite from the matrix with ion chromatography. The ion chromatographic procedure... 

In one study, a modified Monier-Williams method has been utilized as a preparative procedure to obtain both the free and bound sulfite fractions. The two fractions were analyzed by HPLC with indirect photometric detection using a 250 X 4.6-mm LC-SAX column eluted with potassium hydrogen phtalate (0.15 g/L, pH 5.7) and detected at 280 nm. Levels of 5-10 ppm of S02 in foods, corresponding to 30 - 60 ng injected, were reliably detected by this method. The results confirmed that the chromatographic method, unlike the Monier-Williams method, is able to avoid the potential interference of volatile substances derived from matrices or utilized chemicals (36). The HPLC conditions are summarized in Table 3. 

Fruit juices, Monier-Williams Ion-exchange 0.0024 M Na2C03,... 

There have been many modifications for different applications to the original method published by Monier-Williams (1927). However, for fruit juices it is best to use the Tanner modification (Tanner, 1963), which uses phosphoric acid rather than hydrochloric acid for the acidification as this method is less liable to interferences. The method has also been published in the IFU handbook method no. 7a (Anon, 2000) with collaborative ring test data. 

Monier-Williams, G.W. (1927) Determination of sulfur dioxide. Analyst 52, 415-16. 

Acid-induced decomposition is the basis of many methods of determining the presence of sulfite in foodstuffs. One of the best known methods is the Monier-Williams procedure, in which the sample is refluxed with HC1, and the S02 driven off is estimated iodometrically. 

It is important to note, however, that sulfonic acids formed by the addition of bisulfite to a double bond do not decompose on heating with acid, i.e., the Monier-Williams procedure will not assess sulfite bound in this form. 

G. W. Monier-Williams, Trace Elements in Food, John Wiley Sons, Inc., New York, 1950, p. 138. 

FIGURE 43 The Optimized Monier-Williams Apparatus Component Identification Is Given in Text (component F is depicted in FIGURE 44). 

Aldehyde synthesis. Monier-Williams showed that the reagent reacts with a Grignard reagent to give an imine, hydrolyzable to an aldehyde ... 

An interesting booklet by Monier-Williams was Chemistry in Relation to Food. The first text clearly devoted to the physical chemistry of foods from a technological point of view was that of Clayton on Colloid Aspects of Food Chemistry and Technology. ... 

Monier-Williams, G. W., Chemistry in Relation to Food, London, Ernest Benn, Ltd., 1924. Olsen, J. C., Pure Foods—Their Adulteration, Nutritive Value, and Cost, Boston, Ginn, 1911. Richards, E. H. S., and Woodman, A. G., Air, Water, Food from a Sanitary Standpoint, ... 

The best reference that was found was AOAC method 990.31 [18] that was developed by Kim and Kim. The method was based on extensive work with a variety of foods and beverages. The incentive for the work was to find an alternative to the modified Monier-Williams method [23] which is time-consuming and labor-intensive. 

Much of the sulphur dioxide present in beer is in a bound form, for example, as the acetaldehyde bisulphite compound. The classical (Monier-Williams) method for the estimation of sulphur dioxide, adopted by the Institute of Brewing, involves the removal of SO2 from acidified beer in a stream of carbon dioxide and nitrogen at 100 C. The gas is absorbed in hydrogen peroxide and the sulphuric acid formed titrated. In Britain sulphur dioxide is a permitted preservative in beers ( > 70 ppm), ciders, and wines ( > 150 ppm) and the Monier-Williams method is official. The EBC-ASBC adopt a more sensitive colorimetric method in which the colour restored to acid-decolourized rosaniline hydrochloride is measured. 

Sulfurous acid total Foods Modified 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... 

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. 

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