Optimization of Excitation Voltage Amplitude for Collision Induced Dissociation of Ions in an Ion Trap
AssigneeThermo Finnigan LLC
InventorScott T. Quarmby
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Abstract
Collision induced dissociation of precursor ions in an ion trap is performed by determining a predicted fragmentation-optimized excitation voltage amplitude based on an indicator of damping gas pressure, such as a damping gas flow rate, and optionally other parameters including precursor ion m/z and an indicator of the Mathieu parameter q. The excitation voltage may then be applied to electrodes of the ion trap in steps of increasing amplitude, wherein at least one of the amplitudes corresponds to the predicted optimum value. Application of the excitation voltage in this manner produces favorable fragmentation efficiencies over a range of operating parameters and for ions of differing chemical properties.
Claims23
A method of fragmenting precursor ions in an ion trap, comprising:
- applying an excitation voltage to the ion trap, the amplitude of the excitation voltage being based at least in part on the mass-to-charge ratio (m/z) of the precursor ions and an indicator of a damping gas pressure in the ion trap.
An ion trap mass analyzer, comprising:
- a plurality of electrodes defining an interior volume in which precursor ions are trapped;
- a damping gas source for introducing damping gas into the interior volume of the ion trap;
- a trapping voltage source for applying an RF voltage to the ion trap to confine the precursor ions within the interior volume;
- and
- an excitation voltage source for applying an excitation voltage to the ion trap to kinetically excite the precursor ions, the amplitude of the excitation voltage being based at least in part on the mass-to-charge ratio (m/z) of the precursor ions and an indicator of a damping gas pressure in the interior volume of the ion trap.
A method of fragmenting precursor ions in an ion trap, comprising:
- applying an excitation voltage to the ion trap at a plurality of successively increasing amplitudes, at least one of the amplitudes of the plurality of amplitudes being based at least in part on an indicator of a damping gas pressure in the ion trap.
Dependencies are inferred from the claim text.