Validation of a Reversed‐Phase HPLC Method for the Analysis of Sildenafil Citrate in Pharmaceutical Preparations and in Spiked Human Plasma

Abstract A simple, precise, rapid, and accurate reversed‐phase high performance liquid chromatographic (RP‐HPLC) method has been developed for the determination of sildenafil citrate (SLD) in pharmaceutical dosage forms and spiked human plasma. Chromatography was carried out on a C18 reversed‐phase column, using a mixture of acetonitrile:water(45:55, v/v) as a mobile phase at a flow rate of 1 mL · min−1. Phenobarbital sodium was used as an internal standard (IS) and detected using a diode array detector at 220 nm. Retention times of SLD and IS were 7.2 and 3.2 min, respectively. The linear range of SLD was found to be 5×10−8–1×10−5 mol · L−1. Limit of quantitation (LOQ) and limit of detection (LOD) were calculated to be 7.5×10−8 and 2.2×10−8 mol · L−1, respectively. The method was validated for its linearity, precision, accuracy, stability, robustness, and ruggedness. The proposed method was applied to sildenafil tablets and spiked human plasma. In addition, the results were compared with those obtained from UV‐spectrophotometry.