Simultaneous spectrofluorimetric determination of thiamin, pyridoxine and riboflavin in pharmaceutical multivitamin preparations.

Independent spectrofluorimetric methods have been described for the assay of thiamin, pyridoxine and riboflavin in combination. Thiamin determination is based on the spectrofluorimetric measurements of thiochrome formed by the oxidation with N-bromosuccinimide (N-BS) in isopropanol. The method proved to be a stability indicating method. Pyridoxine and riboflavin are estimated by measuring their independent fluorescence in buffer solution pH = 7. The methods are highly specific and can be performed without prior extraction or separation of the individual vitamins. The sensitivity ranges are 1.5-3.5, 0.5-2.5 and 0.4-2.0 micrograms X ml-1 for thiamine, pyridoxine and riboflavin respectively.