A New Approach to Infrared Multiphoton Photodissociation for Controlled Dissociation in a Quadrupole Ion Trap Mass Spectrometer

摘要

Infrared multiphoton photodissociation (IRMPD) of peptides yields many product ions, but the amount of sequential dissociation is difficult to control. If 100percent fragmentation efficiency of the parent ion is achieved, more product ions are observed from IRMPD than from collision-induced dissociation (CID), but the product ions are reduced in abundance. After long irradiation times with extensive sequential dissociation, some product ions fall below the low mass cut-off, reducing MS/MS efficiency. Presented here is a new approach to IRMPD in a quadrupole ion trap where ions are irradiated outside the normal ion cloud while product ions accumulate in the center of the trapping volume. With selective broadband (SB) IRMPD, the activation of product ions is controlled in parallel with manipulation of the q_(z) value to maximize MS/MS efficiency.