Article Title

Extractive spectrophotometric determination of sildenafil citrate (Viagra) in pure and pharmaceutical formulations


Two simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of sildenafil citrate (SC) in pure and pharmaceutical formulations. These methods are based on the formation of chloroform soluble ion-association complexes of SC with brilliant blue G (BBG) and with bromocresol purple (BCP) in KCl-HCl buffer of pH 1.30 (for BBG) and in NaOAc- HCl buffer of pH 3.5 (for BCP) with absorption maximum at 615 nm and 406 nm for BBG and BCP, respectively. Reaction conditions were optimized to obtain the maximum colour intensity. The absorbance was found to increase linearly with increase in concentration of SC, which was corroborated by the calculated correlation coefficient values (0.9991 and 0.9993). The systems obeyed Beer's law in the range of 0.01-4.0 and 0.021-15.0 μg/mL for BBG and BCP, respectively. Various analytical parameters have been evaluated and the results have been validated by statistical data. No interference was observed from common excipients present in pharmaceutical formulations.

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