Charge Remote Fragmentation of Fatty Acid Anions in 400 eV Collisions with Xenon Atoms

In an effort to assess the performance of a new commercial hybrid magnetic sector–time-of-flight tandem mass spectrometer for the structural analysis of fatty acids, collision-induced dissociation spectra of stearic, oleic, linoleic and arachidonic acids have been recorded. Pseudomolecular [M−H]− parent ions were generated by electrospray ionization, accelerated to 4 keV, selected by the double focussing sectors of the tandem mass spectrometer, decelerated to 400 eV and focused into a collision cell containing xenon. The resulting fragment ions were mass analysed by an orthogonal time-of-flight analyser. The CID spectra showed charge-remote fragmentation patterns, from which the location of double bonds could be determined.