Abstract
Investigation was made on the physical and chemical properties and the quantitative determination of thiamine monophosphate disulfide (TMPDS). Ultraviolet absorption spectrum of its aquenous solution is variable with changes in pH, and the isosbestic points are 239 and 277 mμ. Dissociation constants obtained by the titration curve are pKa_1 5.90,pKa_2 7.55,pKb 11.93 and isoelectric point was calculated as pH 3.96. TMPDS is insoluble in organic solvents, but soluble in water, and the solubility decreases to the minimum value at pH 4. Rf is 0.47,when a developing solvent consisted of pyridine, acetic acid, water is used, by the thin layer chromatography. Anhydrous TMPDS is hygroscopic, but its hydrates (4 to 8H_2O) are stable. An aqueous solution of TMPDS is stable for heating at 60〜7O℃ in acidic enviroments, particulary at pH 4,while it is unstable in alkaline solution. TMPDS is reduced quantitatively with cysteine in a pH 13.0 at 35℃ for 15 minutes. Thiamine monophosphate (TMP) thus produced was determined by ultraviolet absorption of flurometric method, since it is also converted to thiochrome phosphate with cyanogen bromide and alkali. When TMPDS, thiamine and TMP are contained together in blood, the total thiamine is satitfactorily determined by usual thiochrome method after cysteine-Takadiastase hydrolysis.
