Negative ion fast atom bombardment mass spectrometry.In situreactions of boronic acids with triols and related compounds, sugars and nucleosides

On the probe tip of a fast atom bombardment mass spectrometer, boronic acids react with a wide range of trifunctional compounds of appropriate configuration yielding negatively-charged boronate cage compounds. Formation of 5- to 8-membered rings occurs readily in the mass spectrometer. The reaction constitutes a simple and effective means of pre-ionizing boronic acids, triols, aminodiols, monomercaptodiols and related compounds including sugars and nucleosides. The resulting boronate complexes exhibit excellent negative ion fast atom bombardment mass spectra, indicating wide application for (1) analysing polyhydroxy compounds and boronic acids, (2) providing information on configuration of polyhydroxy compounds, and (3) measuring affinity constants of polyfunctional compounds for boronic acids. The use of polyethylene glycol as solvent and mass calibrant is also discussed.