Simultaneous Determination of Ten Phosphodiesterase-5 Inhibitors in Health Foods by Ultra Performance Liquid Chromatography with Tandem Mass Spectrometry

A method was developed for simultaneous determination of ten phosphodiesterase-5 (PDE-5) inhibitors in health foods by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), such as vardenafil, acetildenafil, sildenafil, homosildenafil, udenafil, tadalafil, thioaildenafil, gendenafil, pseudovarnafil, norneosildenafil. The separation was performed using water containing 0.1% formic acid and methanol as mobile phases with gradient elution at a flow rate of 0.2 mL/min. Qualitative and quantitative analysis were achieved after the chromatographic separation on a Waters Acquity UPLC BEH C18 column (100 mm×2.1 mm×1.7 μm). The electrospray ionization (ESI) source in positive ion mode was used for analysis of ten phosphodiesterase-5 inhibitors in the multiple reaction monitoring (MRM) mode. The nuclear ratio of parent ion and daughter ion, cone voltage, collision voltage were investigated. The sample was ultrasonic-assisted treatment using the methanol as extraction solvent, and then purified by Waters Oasis HLB solid-phase extraction (SPE) column. The results indicate that the linear range of the method is from 1.0 μg/L to 100.0 μg/L with R²>0.993, which means the method has a good linearity. The limits of detection (LOD) and limits of quantification (LOQ) of ten phosphodiesterase-5 inhibitors are 0.3-1.0 μg/kg and 1.0-2.5 μg/kg, respectively. The average recoveries of ten phosphodiesterase-5 inhibitors at three spiked levels of 100.0, 200.0 and 1 000.0 μg/kg are 85.6%-94.3%. The method was applied to analysis of the investigated compounds in twenty health foods. The results indicate that sildenafil are found in eighteen samples with the range of 1.3-210.8 mg/g, vardenafil and tadalafil are found in a tablet and a capsule, respectively. This method is accurate, simple, rapid and feasible for simultaneous determination of phosphodiesterase-5 inhibitors in health foods.