Continuous-flow fast atom bombardment and field desorption mass spectrometry of oligomers of 3,3,3-trifluoro-1-phenylpropyne

Abstract

Field desorption mass spectrometry was used to determine the chain length, molecular weight range, and Identities of the end-capping groups of synthetic oligomers of 3,3,3-trlfluoro-1-phenylpropyne. In order to obtain structurally significant fragment Ions of selected molecular Ion precursors, the MS/MS technique of ß/ -llnked scanning with colllslonal activation (CAD) was used. Because of the short duration and low Intensity of the signal, no useful MS/MS data could be obtained using FD as the Ionization method. However, 5/E-Hnked scans following CAD could be obtained using fast atom bombardment (FAB) mass spectrometry. To overcome Ion "suppression" of components In the unpurified oligomeric mixture and reduce the chemical noise during FAB, continuous-flow FAB liquid chromatography/mass spectrometry (LC/MS) was used to obtain molecular weight Information comparable to field desorption mass spectrometry. Finally, B/E-linked scanning with CAD was carried out during LC/MS In order to obtain fragment ions confirming the presence of phenyl and trlfluoromethyl substituents on the polyacetylene chain.