Fragmentation pathways of selectively labeled uropranolol using electrospray ionization on an ion trap mass spectrometer and comparison with ions formed by electron impact

Propranolol, deuterium- and O-18-labeled propranolol and related compounds were analyzed using an ion trap mass spectrometer equipped with a modified Finnigan API electrospray interface. Sequential product ion (MSn) experimen ts were used to elucidate fragmentation pathways for these compounds. The o bserved ions were compared to those observed under electron impact (EI) con ditions. The electrospray ionization (ESI) ion trap spectra, as well as the EI spectra, afford useful information to allow assignments of most product ions, many of which retain portions of the aliphatic three-carbon side cha in. Copyright (C) 1999 John Wiley & Sons, Ltd.