Presence of sildenafil, tadalafil and avanafil in food supplements determined by validated high-pressure liquid chromatography-electrospray tandem mass spectrometry method

Food supplements adulterated with analogues pose a pharmacological and toxicological health risk. The scale at which erectile dysfunction (ED) medicines are obtained outside of the official health system rivals and possibly exceeds legitimate sales. The legitimate health systems were dominated by the EMA and FDA approved ED medicines ; Viagra® (sildenafil), Cialis® (tadalafil) and Stendra® (avanafil). According to literature a high-risk segment of this market is occupied by adulterated food supplements. We studied food supplements (capsules, pastes and drinks) purchased from Croatian market or as a row material on sildenafil, tadalafil and avanafil content. Substances were determined by high-pressure liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS-MS). For each substance two transitions was monitored, using protonated molecules as precursor ions and sildenafil D8 as internal standard. The drugs were isolated from food remedies using simple methanol extraction. The target drug was separated using reversed-phase liquid chromatography on chromatographic column Zorbax SB C18 (150 mm × 2.1 mm, 3.5 μm) with an isocratic elution using acetonitrile – 0.1% formic acid mobile phase at a flow rate of 0.2 mL/min. 59 samples were analysed in period from 2012 till 2014. 46% of samples were collected by sanitary inspection and others by private companies. The study showed that sildenafil and tadalafil were detected in 12 samples in range (