Phase-enhanced selective ion ejection in an orbitrap mass spectrometer.

The mass resolution achieved in selective ion isolation using resonance excitation is usually limited by the frequency resolution of the ac waveform and by unintended off-resonance excitation. A new method of phase-enhanced selective ion ejection based on broadband dipolar excitation and ion ejection applicable to the Orbitrap is described and shown to allow an isolation resolution of 28,400. The method is calculated to be able to provide a mass resolution for ion ejection of up to 100,000.