Mass spectrometer with tandem ion mobility analyzers

Patent metadata

Field	Value
Publication number	US-2018340910-A1
Application number	US-201715603600-A
Country	US
Kind code	A1
Filing date	May 24, 2017
Priority date	May 24, 2017
Publication date	Nov 29, 2018
Grant date	—

Abstract

The invention proposes a mass spectrometer comprising two ion mobility analyzers in tandem arrangement, of which at least one is a trapped ion mobility spectrometer (TIMS), and an ion gate which is located between the two ion mobility analyzers, and use thereof wherein ions are selectively transferred between the two ion mobility analyzers by adjusting the transmission of the ion gate while ions are separated in time according to ion mobility in the first ion mobility analyzer.

First claim

1 . A method for analyzing ions in a mass spectrometer comprising an ion source, first and second trapped ion mobility spectrometry (TIMS) analyzers, an ion gate located between the first and second ion mobility analyzers and a mass analyzer, the method comprising the steps of:
transferring ions from the ion source to the first TIMS analyzer; driving the ions transferred to the first TIMS analyzer by a first gas flow against a first counter-acting electric DC field barrier such that the ions are trapped and spatially separated according to their mobilities at different positions along a ramp of the first electric DC field barrier at which a friction force of the first gas flow equals the counter-acting force of the first electric DC field barrier; temporally separating ions according to mobility in the first TIMS analyzer by adjusting a height of the first electric DC field barrier or the velocity of the first gas flow; selecting ions of interest by adjusting the transmission of the ion gate during the temporal ion separation in the first ion mobility analyzer; transferring the selected ions of interest to the second TIMS analyzer; driving the ions transferred to the second TIMS analyzer by a second gas flow against a second counter-acting electric DC field barrier such that the ions are trapped and spatially separated according to their mobilities at different positions along a ramp of the second electric DC field barrier at which a friction force of the second gas flow equals the counter-acting force of the second electric DC field barrier; and temporally separating ions according to mobility in the second TIMS analyzer by adjusting a height of the second electric DC field barrier or the velocity of the gas flow.

2 . (canceled)

3 . The method according to claim 1 , wherein the first temporal separation in the first TIMS analyzer, the selecting of ions of interest and the transfer of selected ions to the second TIMS analyzer are repeated and the second TIMS analyzer is operated to accumulate the repeatedly transferred ions of interest prior to temporally separating them according to mobility in the second TIMS analyzer.

4 . The method according to claim 1 , wherein the transmission of the ion gate is adjusted while the ions are separated in the first TIMS analyzer such that the transmission for a highly abundant ion species of interest is lower than the transmission of less abundant ion species of interest.

5 . The method according to claim 4 , wherein an opening interval of the ion gate for the highly abundant ion species of interest is shorter than an opening interval for the less abundant ion species of interest.

6 . The method according to claim 1 , wherein the transmission of the ion gate is adjusted while the ions are separated in the first TIMS analyzer such that a total space charge of the ions transferred to the second TIMS analyzer and/or a local space charge of the ions transferred to the second TIMS analyzer is below a predetermined threshold.

7 . The method according to claim 1 , wherein the ion gate is opened and closed once while the ions are separated in the first TIMS analyzer such that the transferred ions of interest are substantially from a single mobility range.

8 . The method according to claim 7 , wherein the electric field ramp of the second TIMS analyzer is adjusted such that the transferred ions of interest of the single mobility range spread substantially over a full width of the electric field ramp.

9 . The method according to claim 1 , wherein the ion gate is opened and closed several times while the ions are separated in the first TIMS analyzer such that the transferred ions of interest are substantially from several disjoint mobility ranges.

10 . The method according to claim 1 , wherein the ions which are separated in the second TIMS analyzer are further analyzed by acquiring mass spectra or acquiring fragment mass spectra.

11 . A method for analyzing ions in a mass spectrometer comprising an ion source, first and second trapped ion mobility spectrometry (TIMS) analyzers, a mass filter located between the first and second TIMS analyzers and a mass analyzer located downstream of the second TIMS analyzer, the method comprising the steps of:
transferring ions from the ion source to the first TIMS analyzer; driving the ions transferred to the first TIMS analyzer by a first gas flow against a first counter-acting electric DC field barrier such that the ions are trapped and spatially separated according to their mobilities at different positions along a ramp of the first electric field barrier at which a friction force of the first gas flow equals the counter-acting force of the first electric DC field barrier; temporally separating ions according to mobility in the first TIMS analyzer by adjusting a height of the first electric DC field barrier or the velocity of the first gas flow; filtering the separated ions according to mass in the mass filter wherein a transmitted mass range of the mass filter varies while the ions are separated in the first TIMS analyzer; transferring the filtered ions to the second TIMS analyzer; driving the ions transferred to the second TIMS analyzer by a second gas flow against a second counter-acting electric DC field barrier such that the ions are trapped and spatially separated according to their mobilities at different positions along a ramp of the second electric DC field barrier at which a friction force of the second gas flow equals the counter-acting force of the second electric DC field barrier; and separating the transferred ions according to mobility in the second TIMS analyzer by adjusting a height of the second electric DC field barrier or the velocity of the gas flow.

12 . The method according to claim 11 , wherein the mass filter is operated at a gas pressure above 10 Pascal.

13 . The method according to claim 11 , wherein the ions which are separated in the second TIMS analyzer are further analyzed by acquiring mass spectra or fragment mass spectra.

14 . A mass spectrometer comprising an ion source, first and second trapped ion mobility spectrometry analyzers (TIMS), an ion gate or a mass filter located between the two ion mobility analyzers and a mass analyzer,
wherein the first and second TIMS analyzers each comprise a gas flow and a counter-acting electric DC field barrier configured to spatially separate ions according to their mobilities at different positions along a ramp of the electric field barrier at which a friction force of the first gas flow equals the counter-acting force of the electric DC field barrier and to temporally separate ions according to mobility by adjusting a height of the electric DC field barrier or a velocity of the gas flow, and wherein the ion gate is configured to vary the transmission of ions during operation of the first mobility analyzer and the mass filter is configured to vary the transmitted mass range during operation of the first mobility analyzer, respectively.

15 . (canceled)

16 . (canceled)

17 . The mass spectrometer according to claim 14 , wherein the ion gate is an ion-optical einzel lens or a Bradbury-Nielsen grid.

18 . The mass spectrometer according to claim 17 , further comprising a DC generator and/or an RF generator connected to the Bradbury-Nielsen grid.

19 . The mass spectrometer according to claim 14 , wherein the mass filter is a Loeb-Eiber mass filter.

20 . The mass spectrometer according to claim 14 , further comprising a fragmentation cell between the second TIMS

Assignees

• Bruker Daltonik Gmbh

Inventors

• Betz Thomas
• Park Melvin Andrew
• Ridgeway Mark

Classifications

• H01J49/4225

  Multipole linear ion traps, e.g. quadrupoles, hexapoles · CPC title

• H01J49/004

  Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn · CPC title

• H01J49/0031

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

• H01J49/26

  Mass spectrometers or separator tubes · CPC title

• H01J49/06

  Electron- or ion-optical arrangements · CPC title