Abstract: A method and apparatus for the analysis of a narrow range of fragment ions by application of a notched broadband waveform during ion accumulation within a quadrupole collision cell operated as a linear ion trap. The fragment ions are formed via the axial acceleration and collision activated dissociation of mass resolved precursor ions. A narrow band of frequencies is purposefully omitted from the spectrum, so that the secular frequency of a particular fragment ion will fall within this notch of absent frequencies and as a result will not experience resonant excitation and are retained in the linear ion trap. Simultaneously, all other ions are lost either through neutralization when they strike electrodes or through (additional) collision activated dissociation. Accordingly, a particular mass or range of masses, whose secular frequencies fall within the notch of absent frequencies in the notched broadband waveform, may be selectively accumulated during the collision activated dissociation event.

Abstract: A method and apparatus for the analysis of a narrow range of fragment ions by application of a notched broadband waveform during ion accumulation within a quadrupole collision cell operated as a linear ion trap. The fragment ions are formed via the axial acceleration and collision activated dissociation of mass resolved precursor ions. A narrow band of frequencies is purposefully omitted from the spectrum, so that the secular frequency of a particular fragment ion will fall within this notch of absent frequencies and as a result will not experience resonant excitation and are retained in the linear ion trap. Simultaneously, all other ions are lost either through neutralization when they strike electrodes or through (additional) collision activated dissociation. Accordingly, a particular mass or range of masses, whose secular frequencies fall within the notch of absent frequencies in the notched broadband waveform, may be selectively accumulated during the collision activated dissociation event.