Determination of tadalafil and N-desmethylsibutramine in health and dietary supplements using ultra-performance liquid chromatography (UPLC) coupled with quadrupole-time-of-flight mass spectrometry (Q-TOF MS)

The adulteration of dietary supplements with drugs is potentially dangerous for human health. In this study, a method was used to test simultaneously for the presence of three synthetic PDE-5 inhibitors (sildenafil, vardenafil and tadalafil), and sibutramine and its two major metabolites (N-desmethylsibutramine and N-didesmethylsibutramine) using ultra-performance liquid chromatography (UPLC) coupled with quadrupole-time-of-flight mass spectrometry (Q-TOF MS) in dietary supplements. This approach with UPLC/Q-TOF MS uses the high accurate mass of six compounds for identification and has a short run time. The recovery was from 87% to 113%; precision was less than 12.8%. The limit of detection and limit of quantification were from 0.4 to 2.0 μg kg^-1 and from 1.3 to 6.0 μg kg^-1, respectively. This method allows easy and fast analysis and detection of diverse adulterants.