MECHANISM OF LOW-PRESSURE CHEMICAL IONIZATION MASS-SPECTROMETRY

Chemical Ionization mass spectrometry at sample pressures as low as 10-9 Torr can be accomplished with a Fourier transform mass spectrometer based upon the ion cyclotron resonance (ICR) principle. Generally ICR has been considered to be a low-performance mass spectrometer, but enormous progress has been made recently In improving the mass resolution, mass range and scan rate. By combining a one-region ICR cell with a Fourier transform ion detection method, a truly high-resolution, rapid-scanning mass spectrometer has been developed. A mechanism for generation and storage of ions in the ICR cell is proposed and validated by a number of experimental tests. The chemical and physical processes in the ICR cell are well behaved and projections are made of how even greater detection sensitivity can be achieved. By relying on computer technology rather than precision machining, ICR may become the high-performance mass spectrometric technique of the future. © 1979, American Chemical Society. All rights reserved.