Linear and Nonlinear Resonance Ejection of High Mass Ions with charge detection rectilinear ion trap mass spectrometer

We present the linear and nonlinear resonance ejection of high mass-to-charge (m/z) ratio of protein ions with charge detection rectilinear ion trap mass spectrometer (CD RIT-MS). The measurements of ejected high mass ions with dipolar resonance ejection in the presence of high order fields are demonstrated. With linear resonance ejection, it was found the measured ion number could be enhanced by a factor of 3-5 as compared to that with boundary ejection. With nonlinear resonance ejection (with high order fields), e.g. a positive octopolar field, the ion number can be enhanced by a factor of 4-6 as compared to that with boundary ejection. Mass resolution is slightly improved with nonlinear resonance ejection (similar to 1.4 for cytochrome C ions) as compared to linear resonance ejection and about a factor of 5 improvements as compared to boundary ejection. In addition, when analyzing heavier bovine serum albumin (BSA) ions, it was observed that co-occurrence of boundary and resonance ejection was prominent with respect to m/z values, iso-beta points, and auxiliary AC resonance amplitude where the ejection was below an octopolar field point of beta(u) = 0.70. (C) 2020 Elsevier B.V. All rights reserved.