Abstract
Simple, selective and reproducible spectrophotometric methods have been developed for the determination of thiamin and riboflavin concentrations in bulk and their pharmaceutical dosage forms using pure formulations and pharmaceutical formulations of chromazurol S (CAS). This method is based on the ion-association between the drugs and the acid dye (CAS) in weak base media in the presence of Triton X-100 as a solubilizing agent. The absorption factor was calculated to estimate thiamin and riboflavin concentrations in mixtures without previous separation by applying the absorption factor method and absorbance subtraction method.