title: Simultaneous determination of synthetic phosphodiesterase-5 inhibitors found in a dietary supplement and pre-mixed bulk powders for dietary supplements using high-performance liquid chromatography with diode array detection and liquid chromatography-electrospray ionization tandem mass spectrometry.
abstract: A high-performance liquid chromatography-diode array detection (HPLC-DAD) method and a liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method were developed to screen for the presence of synthetic phosphodiesterase-5 (PDE-5) inhibitors and their analogues, namely sildenafil, vardenafil, tadalafil, homosildenafil, acetildenafil and hydroxyhomosildenafil. The methods were applied to pre-market samples submitted to the Health Sciences Authority of Singapore (HSA) for testing. One sample was in the form of capsules while six other samples were pre-mixed bulk powder samples for dietary supplements to be repackaged or formulated into the final dosage forms (usually capsules). Identification of PDE-5 inhibitors and their analogues was achieved by comparing individual peak retention times, UV spectra and mass spectra with those of reference standards. The seven samples were found to contain at least one of the following compounds: sildenafil, vardenafil, hydroxyhomosildenafil, homosildenafil and acetildenafil. The five compounds were simultaneously determined by LC-ESI-MS/MS in multiple reactions monitoring (MRM) scan mode. The method has been validated for accuracy, precision, linearity and sensitivity.
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Science Drive 4, Singapore 117543, Singapore.
authors.forename: Peng
authors.initials: P
authors.lastname: Zou
authors.forename: Sharon Sze-Yin
authors.initials: SS
authors.lastname: Oh
authors.forename: Peiling
authors.initials: P
authors.lastname: Hou
authors.forename: Min-Yong
authors.initials: MY
authors.lastname: Low
authors.forename: Hwee-Ling
authors.initials: HL
authors.lastname: Koh
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D019587:Dietary Supplements / Q000032:analysis*; D010726:Phosphodiesterase Inhibitors / Q000032:analysis*; D010727:Phosphoric Diester Hydrolases / Q000187:drug effects*; D011208:Powders / Q000737:chemistry*; D012015:Reference Standards; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D010726:Phosphodiesterase Inhibitors; D011208:Powders; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5