Controlled ion fragmentation in a 2-D quadrupole ion trap for external ionaccumulation in ESI FTICR mass spectrometry

Undesired fragmentation of electrospray generated ions in an rf multipole t raps can be problematic in many applications. Of special interest here is i on dissociation in a 2-D quadrupole ion trap external to a Fourier transfor m ion cyclotron resonance mass spectrometer (FTICR MS) used in proteomic st udies. In this work, we identified the experimental parameters that determi ne the efficiency of ion fragmentation. We have found that under the pressu re conditions used in this study there is a specific combination of the rad ial and axial potential well depths that determines the fragmentation thres hold. This combination of rf and dc fields appears to be universal for ions of different mass-to-charge ratios, molecular weights, and charge states. Such universality allows the fragmentation efficiency of the trapped ions i n the course of capillary liquid chromatography (LC) separation studied to be controlled and can increase the useful duty cycle and dynamic range of a FTICR mass spectrometer equipped with an external rf only 2-D quadrupole i on trap. (C) 2001 American Society for Mass Spectrometry.