title: Application of high-performance liquid chromatography with charged aerosol detection for universal quantitation of undeclared phosphodiesterase-5 inhibitors in herbal dietary supplements.
abstract: Incidents of detecting novel analogues of phosphodiesterase 5 (PDE-5) inhibitors in illicit dietary supplements for erectile dysfunction are constantly reported. However, little is known about their content in a single dose, mainly due to the poor availability or inaccessibility of pure reference standards. This study presents a new strategy of quantitative analysis of unknown and recently identified compounds. Charged aerosol detector (CAD), described as "universal detector", combined with high-performance liquid chromatography (HPLC) system proved to be a useful tool for fast and simple quantitation of PDE-5 inhibitors' analogues in a complex herbal matrix without individual reference standards available. Universal calibration was employed for calculations. Two easily obtainable reference materials - sildenafil and tadalafil - were selected as universal standards and the content of analogues was estimated with respect to their response. The error of proposed indirect determination was found to be ± 3%, which is less than enough to obtain a reliable result of the content. The elaborated method was applied for quantitative analyses of PDE-5 inhibitors and 10 analogues detected in 22 illicit dietary supplements and two bulk powdered herbal materials. All target analogues were identified using time-of-flight mass spectrometry with electrospray ionization. Obtained results indicate that the quantity of PDE-5 inhibitors in all tested samples is considered to be pharmacologically relevant.
authors.affiliation: Pharmaceutical Chemistry Department, National Medicines Institute, 30/34 Chelmska Street, 00-725 Warsaw, Poland. m.poplawska@nil.gov.pl
authors.forename: Magdalena
authors.initials: M
authors.lastname: Poplawska
authors.forename: Agata
authors.initials: A
authors.lastname: Blazewicz
authors.forename: Kinga
authors.initials: K
authors.lastname: Bukowinska
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Fijalek
mesh_terms: D000336:Aerosols / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis*; D004340:Drug Contamination; D029001:Herbal Medicine / Q000379:methods; D019999:Pharmaceutical Solutions / Q000032:analysis / Q000737:chemistry; D058986:Phosphodiesterase 5 Inhibitors / Q000032:analysis* / Q000737:chemistry; D028321:Plant Preparations / Q000032:analysis* / Q000737:chemistry; D011208:Powders / Q000737:chemistry; D012015:Reference Standards; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D015813:Substance Abuse Detection / Q000379:methods*
chemical_list: D000336:Aerosols; D019999:Pharmaceutical Solutions; D058986:Phosphodiesterase 5 Inhibitors; D028321:Plant Preparations; D011208:Powders
keywords: Adulteration; Charged aerosol detector; Counterfeit dietary supplement; PDE-5 inhibitor; Universal calibration