COMPARISON OF MASS-SPECTROMETRIC METHODS FOR STUDYING THERMALLY LABILE COMPOUNDS - RIFAPENTINE

Results of 16 different mass spectrometric ionization and sample‐introduction methods are compared for the case of a thermally very labile antibiotic, rifapentine. These suggest that extensive thermal decomposition occurs during evaporation when the sample can come into contact with hot metal parts, usually the source housing. The intensity of the molecular ion and the extent of fragmentation depend on various parameters, such as the ionization process, positive or negative‐ion detection and the type of sample introduction. The most informative methods for rifapentine seem to be ‘in‐beam’ electron impact, negative ionization with particle beam and direct liquid introduction interfaces and positive‐ and negative‐ion fast atom bombardment. Copyright © 1990 John Wiley & Sons, Ltd.