High-performance Liquid Chromatographic Analysis of Sildenafil Citrate and Methyltestosterone Adulterants in a Herbal Medicine

Sildenafil citrate (Viagra) and methyltestosterone were detected in herbal medicine capsules from mainland China by thin layer chromatography (TLC), ultraviolet spectrometry (UV), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass-mass spectrometry (LC-MS-MS). The sample was further assayed by high-performance liquid chromatography (HPLC). Separation was conducted on an Inertsil ODS-2 reversed-phase column using gradient: elution with acetonitrile and 0.1 % (v/v) phosphoric acid as the mobile phase. Propyl paraben was used as an internal standard and the monitor wavelength was 254 nm. Calibration curves of standard sildenafil citrate and methyltestosterone were constructed in the range of 80-800 and 20-200μ/m L, respectively. The relative standard deviations of sildenafil citrate and methyltestosterone for intra-day and inter-day analyses were 0.54-3.56 % and 1.62-3.75 %, respectively. The recoveries of the synthetic drugs from herbal medicine ranged from 98.0 to 100.4 %. The sildenafil citrate and methyltestosterone content in herbal medicine was 20.0 and 1.6 mg/cap, respectively.