Dyes, hydrogen peroxide determination

Phthalein dyes, hydrogen peroxide determination, 628-9 Phthaloyl peroxide, luminol chemilumine scence, 1245 Physiological matrices... 

Dilauroyl peroxide, determination, 701 Dimesityldioxirane, 26, 1133-4 3-(Dimethylamino)benzoic acid hydrogen peroxide determination, 635 oxalate determination, 633 DimethylaniUne, quinoneimine dyes, 630... 

The influence of substituents on the rates of degradation of arylazo reactive dyes based on H acid, caused by the action of hydrogen peroxide in aqueous solution and on cellulose, has been investigated [43]. The results suggested that the oxidative mechanism involves attack of the dissociated form of the o-hydroxyazo grouping by the perhydroxyl radical ion [ OOH]. The mechanism of oxidation of sulphonated amino- and hydroxyarylazo dyes in sodium percarbonate solution at pH 10.6 and various temperatures has also been examined. The initial rate and apparent activation energy of these reactions were determined. The ketohydrazone form of such dyes is more susceptible to attack than the hydroxyazo tautomer [44]. 

ALTERNATE PROTOCOL 2 ENZYMATIC MEASUREMENT OF CHOLESTEROL Test combination kits for enzymatic determination of cholesterol in food are now commercially available. For the determination of total cholesterol, esterified cholesterol is hydrolyzed to free cholesterol and fatty acid under mild alkaline conditions. Cholesterol oxidase oxidizes free cholesterol to cholest-4-en-3-one to generate hydrogen peroxide, which further oxidizes methanol to formaldehyde. Formaldehyde then reacts with acetyl acetone in the presence of NH4+ ions to form yellow lutidine dye, which is subsequently determined spectrophotometric al 1 y. 

Benzidine was used extensively in the manufacture of dyes. Because of its cancer-causing effects in humans, its application in dyes has been curtailed. Other uses of this compound are in chemical analysis as a reagent for the determination of hydrogen peroxide in milk and in the analysis of nicotine. Its hydrochloride is used as a reagent to analyze metals and sulfate. 

---