Applicability of the modified thiochrome method for the determination of thiamine in multivitamins preparations

The applicability of the modofied fluorometric method for the determination of thiamine and its phosphate esters in food for the determination of thiamine-chloride-hydrochloride in multivitamine preparations was investigated. The method is based on alkaline oxidation of thiamine to highly fluorescent thiochrome. The procedure gives satisfactory recovery (87.81 %-100.54%) and a relative standard deviation of parallel determination range between 1.87% and 8.16% (meaqn 4.51%). The acceptability of the method was evaluated after criteria suggested by the Analytical Reference Servis. The total error of discrete determination of thiamine-chloride-hydrochloride ranged between 8.78% and 21.47% (mean 15.95°%), so the proposed simple, rapid and easy to perform procedure is rated an excellent method and acceptable for determination of thiamine-chloride-hydrochloride in control of multivitamin preparations. Deviation of determined thiamine-chloride-hydrochloride content from declarative on the investigated pharmaceutical products ranged from -12.99% to +0.55% and are in agreement with the limits regulated by Pharm. (+- 15%).