Resonant RF Circuit Enables Ion Containment and m/z-Dependent Axial Ejection for Corrected Time-of-Flight Discrimination

Abstract

Time-of-flight m/z discrimination limits the effective analytical m/z range for Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry because optimal ion arrival time at the ICR cell varies with m/z^1/2. Previously, an auxiliary RF waveform that allowed sequential m/z-dependent axial ejection from an external ion accumulation multipole resulted in mitigation of time-of-flight m/z discrimination, which improved ion transfer across a decade in the m/z range 200–2000. Here, a resonant RF axial ejection system based upon the same principle is implemented to further expand the m/z range that can be observed in a single mass spectrum. This new RF ejection system was installed without any change to the internal vacuum components. The RF ejection system has been significantly simplified over the initial implementation and installed and verified on several FT-ICR mass spectrometers in a multilab collaboration.