Recent studies on the mechanism of ionization during thermospray liquid chromatography-mass spectrometry have extended earlier work and substantiated the conclusion that, for most analytes, ion formation is predominantly a gas phase process akin to chemical ionization. The finding has important implications for the prediction of suitable experimental conditions for new analytes. Tandem mass spectrometry of acylcarnitines and steroid glucuronides has indicated appropriate conditions for the analyses, with a particular view to the differentiation of isomers. These studies have additionally improved understanding of the processes of ion production following fast atom bombardment and of collisionally activated decomposition.
