IDENTIFICATION OF NINE CORTICOSTEROIDS WITH HIGH PERFORMANCE LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

AIM: To develop a specific, sensitive and rapid LC/MSⁿ assay for corticosteroids, and provide a detection method for restricting abuse of these drugs. METHODS: Reversed phase high performance liquid chromatography/UV/electrospray ion trap mass spectrometry was used to separate and identify nine corticosteroids, including dexamethasone acetate, prednisone acetate, prednisolone, hydrocortisone, cortisone acetate, hydrocortisone acetate, 17α hydroxydeoxycorticosterone acetate, fluocinonide acetate and triamcinolone acetonide acetate, which were selected as model compounds because of their clinical interest. The UV detection wavelength was fixed at 240 nm. The mobile phase composed of acetonitrile and ammonium acetate buffer (pH 3.5) and was carried out in gradient mode. The mass spectrometer (Finnigan LCQ) was operated in the positive mode and in three scan modes including full scan MS, selected ion monitoring and full scan MS². The obtained mass spectra were analyzed with assistance of the software Mass Frontier 1.0 for their fragmentation passways. RESULTS: Nine corticosteroids were identified simultaneously by LC/MS n and the identification was not affected by excipients and matrix. The full scan MS² spectra of the compounds containing fluorine atom or acetate group gave characteristic fragment ions of losing hydrogen fluoride M+H-20⁺ and acetic acid M+H-60⁺, respectively. This method was successfully applied to identify corticosteroids contained in drug formulations, urine and specimen doubted illegally mixing corticosteroids, with a detection limit of 6 ng for each corticosteroid. CONCLUSION: These chromatographic and mass spectrometric characteristics can be used for qualitative analysis of corticosteroids in vivo or in vitro, and provide potential application to study the metabolism and pharmacokinetics of corticosteroids.