Liquid ionization mass spectrometry for studies of hydrogen-bonded clusters and of a mixture that contains non-volatile and less polar organic compounds

Abstract

Ionization methods that operate under atmospheric pressure, such as ESI and APCI, are now indispensable for measuring nonvolatile organic compounds, and they provide useful interfaces for LC/MS. These methods, however, have several disadvantages; e.g., less sensitivity for less polar compounds (e.g., hydrocarbons and organometallic compounds) and a limitation in the use of solvents. Liquid ionization mass spectrometry utilizes excited argon atoms to ionize liquids at atmospheric pressure. Therefore, it provides information about the hydrogen-bonded clusters that are present in a gas phase and at the liquid surface, and also about solvation. It is also applicable to the analysis of a mixture that contains nonvolatile, either polar or nonpolar, organic compounds. The method provides different applications in the field of mass spectrometry. This review describes the principles and applications of this method, and compares it with other soft ionization methods. © 1998 John Wiley & Sons, Inc., Mass Spec Rev 17, 51–69, 1998