Characterization of β-lactams by photodissociation and collision-activated dissociation in a quadrupole ion trap

Abstract

Electrospray ionization was used to introduce β-lactams, including cephalosporin and penicillin analogs, into a quadrupole ion trap for analysis by collision-activated dissociation (CAD) and infrared multiphoton dissociation (IRMPD). The two dissociation methods provided similar spectra; however, photodissociation requires substantially less tuning than is typically required to optimize CAD. Moreover, IRMPD was effective even at the elevated pressures introduced by the electrospray source. Both CAD and IRMPD promote cleavage across the β-lactam ring, resulting in highly diagnostic fragmentation patterns. Time-resolved and SWIFT methods were used to determine fragmentation genealogies of the ions created by IRMPD. © 1998 John Wiley & Sons, Ltd.