非水溶媒滴定によるバルビツール酸類および市販製品の定量法

概要

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A rapid and accurate method for visual non-aqueous titration of barbituric acid has been presented. The recommended procedures are as follows. Pure barbituric acid: 350450 mg of the acid is dissolved in 50 ml of chloroform-ethanol (10:1) or dimethylformamide by stirring with 1 ml of 0.1% Alizarine Yellow GG-0.1% Thymolphthalein mixture (1:2), and titrated to violet or green blue end point with 0.1N potassium hydroxide in ethanol. Sodium barbiturate and its tablets: 500mg of sample dissolved in 15 ml of water is taken in a separatory funnel with 10 ml of 10% hydrochloric acid. The liberated barbituric acid is extracted into chloroform. The extract (150 ml in volume) washed with water is filtered and, after the addition of 10 ml of ethanol and 2 ml of 0.1% Alizarine Yellow GG-0.1% Thymolphthalein mixture(1:2), is titrated with 0.1N potassium hydroxide in ethanol as above. Barbituric acid tablets: Twenty tablets are powdered and 1 g is taken in a 100 ml volumetric flask. Seventy milliliter of chloroform-ethanol (10:1) is added, shaken for 15 min., and after 30 min. made up to 100 ml with the chloroform-ethanol. It is then filtered throuth a glass filter, and its 50 ml aliquot is titrated as above.