Abstract
Investigation was made on the synthesis and the physicochemical properties of thiochrome (Thc), thiochrome monophosphate (Thc-MP) and thiochrome diphosphate (Thc-DP). Rf values of Thc, Thc-MP and Thc-DP are 0.37,0.16 and 0.05,repectively, when a developing solvent consisting of 1M formate buffer, isopropanol and water (15 : 65 : 20) is used. Ultraviolet absorption and fluorescence spectra of their aqueous solution were measured at various pHs. It was found that absorption and fluorescence maxima of these compounds shifted to longer wave lengths with decreasing pH. In alkaline solution, absorption and fluorescence maxima of these compounds locate 370 and 450 mμ, respectively. On the other hand, fluorescence intensity is influenced with the phosphate-groups and the ratio of fluorescence intensity, Thc : Thc-MP : Thc-DP, is 10 : 8 : 9 in alkaline solution (pH9-12). The concentration of thiamine, thiamine monophosphate and thiamine diphosphate was determined by the well-known method without dephospholization. A reasonable result is obtained when bromine cyanide is used as an oxidizing agent, whereas an unreasonable result is obtained when potassium ferricyanide is used because of the quenching effect of potassium ferricyanide for the fluorescence of thiochrome derivatives.
