High Performance Liquid Chromatographic Method for Determination of Sildenafil Citrate (Viagra) in Pharmaceutical Formulation and Industrial Effluent Sample

A simple, precise, rapid and accurate reversedphase high performance liquid chromatographic method has been developed for the determination of sildenafil citrate in a pure form, pharmaceutical formulations and industrial effluent samples. Chromatography was carried out on supelco L7 reversed- phase column (25cm 4.6mm), 5 microns, using a mixture of methanol: water: triethylamine (630: 370 :2 v/v/v) and adjusted to pH 4.0 with dilute phosphoric acid as a mobile phase at a flow rate of 1.0 ml.min-1.Uv detection was performed at 220 nm at ambient temperature (25 C). The retention time for sildenafil citrate found to be 4.6 minutes. The calibration curve was linear (r= 0.9998) over a concentration range from 10 to 70 g/ml. Limit of detection (LOD) and limit of quantification (LOQ) were 60 ng/ml and 180 ng/ml respectively. The method was validated for its linearity, precision and accuracy. The proposed method was successfully applied to the determination of sildenafil citrate in tablets and industrial effluent samples.