Liquid Ionization Mass Spectrometry of Nonvolatile Organic Compounds

Abstract

Characteristics of a technique termed liquid ionization mass spectrometry for organic compounds are described. In particular the use of additives (solvent, matrix, and reagent) for nonvolatile compounds and ease of sample handling are reported. Metastable argon atoms are used to Ionize compounds at atmospheric pressure. Samples are placed on a needle tip positioned near an aperture leading to the mass analyzer. The needle Is heated and a high voltage (about 1 kV) Is applied to the needle. Mass spectra obtained by this method showed Ions characteristic of the molecular weight and the structure of the compounds. Liquid alkane(s) Is a good matrix for nucleosides, while glycerol Is good for phosphatidylcholines. A minute amount of a reagent such as ethanolamlne Increases the abundance of MH+ Ions of sucrose, resulting In reproducible mass spectra. The use of several reagents (e.g., D20) for one compound Is suggested In order to obtain additional structural Information. The advantages of the method are also described. © 1984, American Chemical Society. All rights reserved.