PROBING THE ENERGETICS OF CHARGE-REMOTE FRAGMENTATION IN CARBOCYANINEDYES USING COLLISION-INDUCED AND SURFACE-INDUCED DISSOCIATION MASS-SPECTROMETRY

Carbocyanine dyes used as molecular probes are symmetric ring compound s with long alkyl chains on each ring proximate to a resonance-stabili zed charge site. They provide high-quality positive-ion liquid second (LSI) and electrospray ionization mass spectra in which the intact cat ion is the dominant ion in the mass spectrum. The intact cation of a c arbocyanine dye undergoes charge-remote fragmentation (CRF), evident i n the LSI mass spectra. CRF is also observed in collision-induced diss ociation and surface-induced dissociation of the mass-selected intact cation. Differential CRF processes from the two chains in the molecule are observed with increasing internal energy deposition. (C) 1998 Joh n Wiley & Sons, Ltd.