A CHEMICAL REAGENT FOR THIAMINE

Abstract

The rapid advances in the study of the physiological r81e of thiamine (vitamin B,) make its direct quantitative estimation highly desirable.Few chemical tests have been proposed which offer the prospect of application to solutions or concentrates for this purpose.Jendrassik (1) while working in our laboratory tried to find a specific chemical reagent which would produce a qualitative color reaction with the antineuritic vitamin.He found that solutions containing this vitamin invariably reduced ferric ferricyanide to form blue-colored solutions, which he assumed owed their color to the presence of Prussian blue (ferric ferrocyanide).Levine (2) made a critical study of Jendrassik's reaction and found that this test was given by ortho-and polyphenols.Nevertheless the use of ferricyanide may have suggested a line of thought to Barger (3), who oxidized the vitamin with alkaline ferricyanide to form a pale yellow-blue fluorescent compound now known as thiochrome.The thiochrome test has been made the basis of a method for the quantitative estimation of thiamine by Jansen (4), who used the fluorometer apparatus of Cohen (5) for measuring the fluorescence of the thiocrome after it had been extracted with isobutyl alcohol.Certain substances interfere with this reaction, since complete recovery of thiamine added to urine cannot be obtained.