Patent ID: 9312114
Filing Date: 2016-04-12
CPC Classification: H01J

Claim Text:
1. A method of ejecting ions to be analysed from a quadrupole ion trap in which a trapping field is created by one or more RF voltages applied to one or more electrodes of the trap, the method comprising the following steps: (a) cooling the ions to be analysed within the quadrupole ion trap until the ions are thermalized; (b) reducing the amplitude of one or more RF voltages applied to the quadrupole ion trap and applying the one or more reduced amplitude RF voltages for substantially one half cycle from where the one or more RF voltages have reached a zero crossing point; (c) turning off the one or more RF voltages applied to the quadrupole ion trap after the one half cycle; steps (a) to (c) being performed in that order; and (d) ejecting the ions to be analysed from the quadrupole ion trap concurrently with or after step (c).