Differential ion mobility separation of isomers for threshold collision-induced dissociation measurements

Abstract

A triple-quadrupole mass spectrometer adapted for threshold-collision-induced dissociation (TCID) measurements was modified by replacing the standard mass spectrometer front-end with a Fernandez de la Mora-type differential mobility analyzer (DMA). Using a combination of a drift field and an orthogonal laminar gas flow at atmospheric pressure, an ion of a given mobility (DMA voltage) can be isolated from a continuous stream of electrosprayed ions for TCID measurements. Proof-of-concept DMA-TCID experiments using silver complexes of mixtures of ortho–para and cis–trans isomers as well as silver complexes of the individual isomers show excellent agreement in the determined bond dissociation energies (BDEs) between both sets of experiments as well as with theoretical BDEs predicted by density functional theory.