Application of alizarin red S as an ion-pair reagent for the spectrophotometric determination of Olopatadine Hydrochloride in pharmaceutical formulation

A simple, accurate and precise spectrophotometric method has been developed and validated for the determination of olopatadine hydrochloride in bulk and their pharmaceutical formulation. This method was based on the formation of (yellow) ion –association complex with Alizarin Red S as chromogenic reagent in acidic medium, which is extracted into chloroform. The complex has a maximum absorbance at 425 nm. All variables affecting the reaction were studied and optimized. Beer's law was obeyed in the concentration range of 10–60 µg/mL. The validity of the described method was assessed. The method was successfully applied to the determination of olopatadine hydrochloride in its pharmaceutical formulation