title: Analysis of betamethasone, dexamethasone and related compounds by liquid chromatography/electrospray mass spectrometry.
abstract: A reversed-phase high-performance liquid chromatography/electrospray ionisation mass spectrometry (HPLC/ESI-MS) method has been developed to conclusively differentiate the epimers betamethasone and dexamethasone and various esterification products (betamethasone and dexamethasone 21-acetate, betamethasone and dexamethasone 21-phosphate, betamethasone 17-valerate, betamethasone 21-valerate and betamethasone 17,21-dipropionate) in counterfeit drugs. Good separation with baseline resolution of all epimers or isomers was obtained on a Zorbax Eclipse XDB or Luna C8 column, using a step gradient with mobile phases of 0.05 M ammonium acetate and acetonitrile. Betamethasones can also be distinguished by the relative abundance of their m/z 279 ion in the positive electrospray tandem mass spectra. The LC/MS or LC/MS/MS method developed was successfully applied to the analysis of drug product samples, i.e. creams and tablets.
authors.affiliation: GlaxoSmithKline, Analytical Sciences, Medicines Research Centre, Gunnels Wood Road, Stevenage SG1 2NY, UK.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Arthur
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Wolff
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Carrier
mesh_terms: D001623:Betamethasone / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003907:Dexamethasone / Q000032:analysis*; D005607:Fraud; D005938:Glucocorticoids / Q000032:analysis*; D004364:Pharmaceutical Preparations / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013237:Stereoisomerism
chemical_list: D005938:Glucocorticoids; D004364:Pharmaceutical Preparations; D003907:Dexamethasone; D001623:Betamethasone