title: A sensitive and specific precursor ion scanning approach in liquid chromatography/electrospray ionization tandem mass spectrometry to detect methylprednisolone acetate and its metabolites in rat urine.
abstract: A new, simple, sensitive and specific liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method in precursor ion scanning (PIS) mode has been developed for the rapid detection of methylprednisolone acetate (MPA) and its metabolites in rat urine. A suitable product ion specific for methylprednisolone (MP) and MPA was selected after a fragmentation study on 20 (cortico)steroids at different collision energies (5-40 eV). Urine samples were simply treated with acetonitrile then dried in a SpeedVac system. The method was validated and compared with other PIS methods for detecting corticosteroids in human urine. It was more sensitive, with limit of detection (LOD) and lower limit of quantitation (LLOQ), respectively, of 5 and 10 ng mL(-1). The method was applied for the analysis of rat urine collected before and after (24, 48, 72 h) intra-articular (IA) injection of a marketed formulation of MPA (Depo-Medrol(R)). MS/MS acquisitions were taken at different collision energies for the precursor ions of interest, detected in PIS mode, to verify the MP-related structure. Six different metabolites were detected in rat urine, and their chemical structures were assigned with a computational study.
authors.affiliation: Dipartimento di Scienze Farmaceutiche Pietro Pratesi, Universita' degli Studi di Milano, Via L. Mangiagalli 25, 20133 Milan, Italy. alessia.panusa@unimi.it
authors.forename: Alessia
authors.initials: A
authors.lastname: Panusa
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Aldini
authors.forename: Marica
authors.initials: M
authors.lastname: Orioli
authors.forename: Giulio
authors.initials: G
authors.lastname: Vistoli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rossoni
authors.forename: Marina
authors.initials: M
authors.lastname: Carini
mesh_terms: D000818:Animals; D006801:Humans; D008297:Male; D008775:Methylprednisolone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000652:urine; D000077555:Methylprednisolone Acetate; D015394:Molecular Structure; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000077555:Methylprednisolone Acetate; D008775:Methylprednisolone