Charge-remote fragmentations are energy-dependent processes

Fast atom bombardment-produced [M + Na](+) ions of tristearoylglycerol and [M - H](-) ions of stearic or nervonic acid undergo charge-remote fragmentations (CRFs) to produce one series of product ions reflecting CnH2n+2 losses, whereas electrospray ionization-produced ions fragment to give two series of product ions reflecting CnH2n+2 and CnH2n+1 losses. These results and those from previous studies show that the mechanisms and energetics of CRFs are complex and unsettled. We demonstrate that several pathways are simultaneously involved in CRFs, and the preference for certain pathways (by CnH2n+1 and CnH2n+2 losses) is determined by the internal energy of the compound itself and the ionization and activation energies that are applied to it. (C) 1998 American Society for Mass Spectrometry.