ATMOSPHERIC-PRESSURE-IONIZATION MASS-SPECTROMETRY .1. INSTRUMENTATION AND IONIZATION TECHNIQUES

Mass spectrometer ion sources are normally located inside a high-vacuum envelope. Such low-pressure ion sources can make use of a range of different ionization methods and are in routine use in analytical mass spectrometers. An ion source operating at atmospheric pressure is better suited, and may be essential, for a growing number of applications. Mass spectrometric analysis of samples pyrolyzed under controlled conditions, the combination of liquid chromatography and capillary electrophoresis with mass spectrometry, and the determination of the molecular mass of proteins by electrospray ionization all benefit from, or require, an atmospheric pressure ionization source.