Liquid chromatography mass spectrometry of dexamethasone and betamethasone

Chemical ionization mass spectra of dexamethasone and betamethasone have been obtained via liquid chromatography mass spectrometry using a moving belt interface. These results have confirmed a concentration-dependent competition between thermal degradation and vaporization. Caution should be exercised when dealing with molecules subject to thermal instability since sample introduction via the mechanical transport system does not guarantee evaporation without thermal decomposition.