Chromatographic and mass spectral characterization of budesonide and a series of structurally related corticosteroids using LC–MS

The LC–MS characteristics of budesonide and a series of structurally related corticosteroids were reviewed to commence the construction of a library of chromatographic and mass spectral information to aid identification of budesonide degradation products during formulation stabilization investigations. The LC–ESI +–MS technique employing a Hypersil ® C18 column with a mobile phase of ethanol-acetonitrile-formic acid (pH 3.8; 0.14 mM) (2:30:68, v/v/v) was then used to characterize 23 corticosteroids. Based on their structures, the corticosteroids were classified into three groups: (I) 4-pregnene-3-one steroids; (II) 1,4-pregnadien-3-one steroids with no fluorine substituents; and (III) 1,4-pregnadiene-3-one steroids with fluorine substituents. Chromatographic (retention time and UV absorbance) and mass spectral properties were correlated with the known chemical structures of these corticosteroids. Base peak and mass spectral fragmentation patterns were related to steroid structural characteristics.