Spectrophotometric determination of montelukast sodium in bulk and pharmaceutical formulations

Two simple, sensitive and accurate spectrophotometric methods have been developed for the determination of montelukast sodium in pure and dosage forms. Both Method-A and B are based on the formation of ion association complex with acid dyes BTB and BCP which are extractable into chloroform from the aqueous phase. The colored chromogen for Method-A shows absorption maximum at 410 nm and linear within the limits 5.0-25.0 μg/mL. Method-B produced colored chromogen which is measured at 415nm. Beer’s law is obeyed in the concentration range of 4.0-20.0 μg/mL for the developed method. Different experimental parameters affecting the color development and stability of colored product are carefully studied and optimized. The developed methods could be successfully applied to pharmaceutical formulations. The results obtained are in good agreement with those obtained using official methods.