Determination of PDE-5 inhibitors and appetite suppressants in adulterated dietary supplements using LC/PDA and LC/MS

There have been a number of reports of dietary supplements contaminated with illegal adulterants that threaten consumers' health because of their adverse pharmacological effects. In the present study, a convenient and economic method was developed to detect illegal pharmaceutics, such as PDE-5 inhibitor and appetite suppressants, using liquid chromatography (LC)/photodiode array (PDA) for screening and LC/mass spectrometry (MS) for successive confirmation. Target peaks were identified by comparison of their chromatographic retention times and PDA spectra with those of synthetic standards and finally confirmed by LC/MS. As a result, tadalafil, a PDE-5 inhibitor, and N-desmethylsibutramine, a derivative of sibutramine, were detected in various dietary supplements at concentrations of 13.5-21.9mg and 3.0 mg per single dose, respectively. The present study will contribute to the development of an analytical method enabling rapid screening of a variety of health foods, and the result suggests that consumers should be aware of serious health risks related to these illegal compounds.