Multi-electrode ion trap

Patent metadata

Field	Value
Publication number	US-9437412-B2
Application number	US-201514801642-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jun 27, 2005
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

This invention relates generally to multi-reflection electrostatic systems, and more particularly to improvements in and relating to the Orbitrap electrostatic ion trap. A method of operating an electrostatic ion trapping device having an array of electrodes operable to mimic a single electrode is proposed, the method comprising determining three or more different voltages that, when applied to respective electrodes of the plurality of electrodes, generate an electrostatic trapping field that approximates the field that would be generated by applying a voltage to the single electrode, and applying the three or more so determined voltages to the respective electrodes. Further improvements lie in measuring a plurality of features from peaks with different intensities from one or more collected mass spectra to derive characteristics, and using the measured characteristics to improve the voltages to be applied to the plurality of electrodes.

First claim

The invention claimed is:

1. A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising:
providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, at least one of the inner electrode or the outer electrode comprise an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the array of electrodes including elements of the outer electrode but not elements of the inner electrode or the array of electrodes including elements of the inner electrode but not the outer electrode;
applying voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and
detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ions.

2. The method of claim 1 , wherein the outer electrode is divided into at least four electrodes of the array.

3. The method of claim 2 , wherein the electrodes of the array form at least one pair of detection electrodes, each pair of detection electrodes comprising first and second longitudinally spaced apart detection electrodes.

4. A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising:
providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, the outer electrode divided into at least four electrodes of an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the inner diameters of the at least four electrodes of the array are substantially uniform;
applying voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and
detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ions.

5. The method of claim 2 , wherein the inner diameters of the electrodes of the array are selected to approximate an equipotential line of a hyper-logarithmic field.

6. The method of claim 1 , wherein the inner electrode is divided into a plurality of electrodes of the array.

7. The method of claim 6 , wherein the outer diameters of the electrodes of the array are selected to approximate an equipotential line of a hyper-logarithmic field.

8. The method of claim 1 , wherein the trapping field approximates a hyper-logarithmic field.

9. The method of claim 1 , further comprising introducing the ions into the trapping volume.

10. The method of claim 1 , wherein the array of electrodes including elements of the outer electrode but not elements of the inner electrode and a second array of electrodes includes elements of the inner electrode but not elements of the outer electrode.

11. A method of analyzing ions trapped in a trapping volume of a mass spectrometer, comprising:
providing the trapping volume defined between an inner electrode and an outer electrode surrounding the inner electrode, the inner electrode divided into a plurality of electrodes of an array of electrodes extending in a spaced arrangement along a longitudinal axis of the trapping volume, the outer diameters of the plurality of electrodes of the array are substantially uniform
applying, voltages to the inner and outer electrodes, at least three electrodes of the array of electrodes receive a different voltage, the voltages are applied to the array of electrodes thereby producing a trapping field to trap the ions in a trapping volume such that the ions adopt oscillatory motion along the longitudinal axis and remain constrained in the direction between the inner and outer electrodes; and
detecting mass spectra from the ions using image current detection, a frequency of the oscillatory motion along the longitudinal axis varies according to the mass-to-charge ratios of the ion.

Assignees

• Thermo Finnigan Llc

Inventors

• Makarov Alexander Alekseevich

Classifications

• H01J49/0009 Primary

  Calibration of the apparatus · CPC title

• H01J49/0031

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title

• H01J49/425

  with a logarithmic radial electric potential, e.g. orbitraps · CPC title

• H01J49/22

  Electrostatic deflection · CPC title

• H01J49/282 Primary

  using electrostatic analysers · CPC title