An ion trap and a method for dissociating ions in an ion trap

Abstract

A quadrupole ion trap includes a switch (3) for switching a trapping voltage between discrete voltage levels VH, VL. This creates a digital trapping field for trapping precursor ions and product ions in a trapping region of the ion trap. A gating voltage is applied to a gate electrode (12) to control injection of source electrons into the ion trap. Application of the gating voltage is synchronised with the switching so that electrons are injected into the trapping region while the trapping voltage is at a selected one of the voltage levels and can reach the trapping region with a kinetic energy suitable for electron capture dissociation to take place.

Description

technical field [0001] The present invention relates to an ion trap and a method for dissociating ions in the ion trap, in particular to a quadrupole ion trap and to a tandem mass analysis using the quadrupole ion trap. Background technique [0002] Tandem mass analysis can be achieved by employing an ion trap analyzer, which can be in the form of a magnetic cyclotron (FTICR MS) or a high frequency quadrupole ion trap. In a tandem mass spectrometer, precursor ions with specific mass-to-charge ratios are selected and separated within a trapping volume. The dissociation process is then performed using one of several known activation methods, including collision-induced dissociation (CID), surface-induced dissociation (SID), infrared multiphoton dissociation (IRMPD), and electron capture dissociation (ECD) . The product ions produced by this process are measured using mass scanning to obtain MS 2 Spectrum. If the precursor ion is further selected from the product ion and th...

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