Protonation Sites in Multifunctional Compounds upon Positive Mode ESI in a Linear Quadrupole Ion-trap and Orbitrap

摘要

When the ions were isolated and fragmented in the ion trap, both solvent systems yielded similar results, indicating that the tautomeric ions formed upon ESI had undergone collisions (likely with water) that moved most of the protons to the amino group. When the ions were isolated in the ion trap and fragmented in the HCD cell, the two solvent systems resulted in different fragmentation, as reported earlier. Similar results were obtained when protonated 4-aminobenzoic acids were subjected to ion source CAD.