Abstract
It was confirmed by in vitro experiments and paper chromatography that the simultaneous presence of large quantities of thiamine or its derivatives and riboflavin, caused a formation of unknown fluorescent substance besides lumiflavin and thiochrome, in the determination of riboflavin by lumifiavin method. The fluorescent substance seemed to be derived from thiamine but it was not formed in case of thiamine disulfide except for the case of presence of reducing substances such as blood. The substance was produced by photolysis in alkaline media, it was transferred to chloroform in acidic media and stable for the oxidation by permanganate.
