Phosphodiesterase-5 inhibitors in Chinese tonic liquors by liquid chromatography coupled with quadrupole time of flight mass spectrometry

Chinese tonic liquor is an important dietary supplement in daily use, but it often happens that illicitly adulterated drugs in Chinese tonic liquor could lead to food safety issues. In this survey, an analytical method consisting of a liquid chromatography-quadrupole-time of flight mass spectrometer (LC-Q-TOF-MS), coupled with quick easy cheap effective rugged safe (QuEChERS) pretreatment, was established for identification of phosphodiesterase type 5 enzyme (PDE-5) inhibitors in Chinese tonic liquors. 86 PDE-5 inhibitors were qualitatively analysed by employing information dependent acquisition mass spectrometry (IDA-MS) in comparison with the accurate mass of the protonated molecular ion, isotopic pattern, library and chemical formula. This method was used to test 28 Chinese tonic liquor samples. The results revealed that the IDA-MS screening method is suitable for qualitative analysis of 86 PDE-5 inhibitors. Four samples were found to be adulterated with sildenafil, tadalafil, vardenafil, isopiperazinoafil, nortadalafil and desmethylsidenafil, which was 14.3% of the tested samples.