ATMOSPHERIC-PRESSURE-IONIZATION MASS-SPECTROMETRY .1. INSTRUMENTATIONAND IONIZATION TECHNIQUES

Mass spectrometer ion sources are normally located inside a high-vacuu m envelope. Such low-pressure ion sources can make use of a range of d ifferent ionization methods and are in routine use in analytical mass spectrometers. An ion source operating at atmospheric pressure is bett er suited, and may be essential, for a growing number of applications. Mass spectrometric analysis of samples pyrolyzed under controlled con ditions, the combination of liquid chromatography and capillary electr ophoresis with mass spectrometry, and the determination of the molecul ar mass of proteins by electrospray ionization all benefit from, or re quire, an atmospheric pressure ionization source.