Liquid Chromatography-Mass Spectrometry Hyphenation for Exhaustive and Unambiguous Characterization of Polyoxyethylene Surfactants

A rapid, specific and reliable high performance liquid chromatographic (HPLC) assay of sildenafil in pharmaceutical dosage forms has been developed and evaluated. Reversed phase chromatography was conducted using a mobile phase of methanol: water: acetonitrile (60:20:20) v/v/v, pH 6.1, 0.1% glacial acetic acid, and detection at λ 290 nm. The recovery and coefficient of variation from six tablets containing 50 mg of sildenafil were 100.90% and 0.45% respectively. Replicate regression analysis of three standard plots in the concentration range (0.01–0.2) μg mL^?1 obtained on three different days gave a correlation coefficient >0.999 and the coefficient of variation of the slopes <1.5%. The assay was precise within day and between days as indicated by ANOVA test. It is suggested that the proposed HPLC method should be used for routine quality control and dosage form assay of sildenafil citrate. The proposed method was also used to study the stability of sildenafil citrate in different dosage forms of the drug.