A comparison of overtone and fundamental resonances for mass range extension by resonance ejection in a quadrupole ion trap mass spectrometer

Abstract

Mass range extension in a quadrupole ion trap has been investigated using resonant ejection of ions at the fundamental secular frequency (ω z ) and at the Ω-ω z overtone resonance frequency, where Ω is the drive rf angular frequency. The procedure is demonstrated for two commercial ion trap spectrometers operated at different drive rf frequencies. Higher rf amplitudes were required for ion ejection at low q z values using the Ω-ω z resonance than at the fundamental secular frequency, resulting in lower observed mass range enhancements for the Ω-ω z resonance at the same rf amplitude. Resonance excitation tandem mass spectrometric experiments also show lower energy deposition for the Ω-ω z resonance, although the effect is less marked at higher q z values.