The application of mass spectrometry to steroids has been extensively developed since its inception in 1956. Detailed studies based on pure steroids and their isotope labelled analogues have established the major pathways of fragmentation under electron impact. The resulting correlations have been of great value in the analytical characterization of steroids and their metabolites. The combination of mass spectrometry with gas chromatography is particularly powerful: the latter technique reduces the complexity of samples, and provides independent characterization by virtue of retention regularities. These features are essential for distinguishing many stereoisomeric or otherwise closely related steroids. Modifications of functional groups can augment the utility of mass spectrometry in qualitative and quantitative analysis. Derivatives may be chosen to alter fragmentation modes, or to produce informative shifts in ion masses within an essentially unchanged fragmentation pattern. Enhancement of molecular ion abundance is usually achievable with derivatives, or by means of milder ionization techniques such as chemical ionization.
Immunohistochemical characterization of the inflammatory infiltrate in placental Chagas' disease: a qualitative and quantitative analysis.
