# US 9,753,011 B2 · Apparatus and methods for ion mobility spectrometry

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- Number: US 9,753,011 B2
- Document ID: US9753011B2
- Status: Granted
- Kind: B2
- Application number: 14/947,119
- Filed: 2015-11-20
- Published: 2016-03-24
- Granted: 2017-09-05
- Earliest claimed: 2012-02-21
- Assignees: Thermo Fisher Scientific (Bremen) GmbH
- Applicants: Thermo Fisher Scientific (Bremen) GmbH
- Inventors: Alexander Makarov
- Web page: https://patentgrep.com/patent/US9753011B2

## CPC

- G01N 27/622: Ion mobility spectrometry
- H01J 49/0031: {Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence)}
- H01J 49/004: {Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn}
- H01J 49/061: {Ion deflecting means, e.g. ion gates}
- H01J 49/063: {Multipole ion guides, e.g. quadrupoles, hexapoles}
- H01J 49/24: Vacuum systems, e.g. maintaining desired pressures
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A method of ion mobility spectrometry wherein ions undergo multiple stages of ion mobility separation and multiple stages of inertial ion motion wherein the mean free path between ion collisions with gas is significantly longer than in the stages of ion mobility separation, wherein each stage of inertial ion motion lies between successive stages of ion mobility separation.

## Claims

### Claim 1

A method of ion mobility spectrometry wherein ions undergo multiple stages of ion mobility separation in a drift space region and multiple stages of inertial ion motion wherein the mean free path between ion collisions with gas is longer than in the stages of ion mobility separation, wherein each stage of inertial ion motion lies between successive stages of ion mobility separation to reflect or deflect ions back through the drift space region for a next stage of ion mobility separation to increase ion mobility separation until a desired level is achieved, a drift time separation is maintained between the ions in the stages of inertial ion motion.

### Claim 2 (depends on 1)

A method as claimed in claim 1, wherein the ions are reflected by an ion mirror or deflected by a deflector in regions of inertial ion motion.

### Claim 3 (depends on 2)

A method as claimed in claim 2 wherein the ions are reflected or deflected by a non-linear electric field.

### Claim 4 (depends on 3)

A method as claimed in claim 3 wherein the non-linear electric field provides time of flight focusing of the ions.

### Claim 5 (depends on 3)

A method as claimed in claim 3 wherein the non-linear electric field is a parabolic field or polynomial field.

### Claim 6 (depends on 3)

A method as claimed in claim 3 further comprising accelerating the ions immediately prior to reflecting or deflecting them in the non-linear electric field.

### Claim 7 (depends on 2)

A method as claimed in claim 2 wherein the regions of inertial ion motion are at lower pressure than a drift space where the ion mobility separation occurs, wherein the regions of inertial ion motion are adjacent to opposite ends of the drift space for reflecting or deflecting the ions at each end of the drift space.

### Claim 8 (depends on 7)

A method as claimed in claim 7 wherein the drift space is filled with a buffer gas and the regions of inertial ion motion are contained is at high vacuum.

### Claim 9 (depends on 1)

A method as claimed in claim 1 further comprising extracting ions from a drift space where the ion mobility separation occurs after separating them by their ion mobility.

### Claim 10 (depends on 9)

A method as claimed in claim 9 wherein the ions are extracted from the drift space through an ion mirror or ion deflector.

### Claim 11 (depends on 9)

A method as claimed in claim 9 further comprising storing the extracted ions in an ion storage device prior to further processing comprising one or more of: further ion mobility separation, ion fragmentation and mass analysis.

### Claim 12 (depends on 1)

A method as claimed in claim 1 wherein the ions are introduced into a drift space where the ion mobility separation occurs through an ion mirror or an ion deflector.

### Claim 13

An ion mobility spectrometer comprising: one or more drift spaces for separating ions according to their ion mobility; and one or more regions for allowing the ions to undergo inertial ion motion wherein their mean free path between collisions with gas is longer than in the one or more drift spaces, wherein each of the one or more regions is configured to receive the ions from one of the one or more drift spaces and comprises ion optics to reflect or deflect the ions into the same or another one of the one or more drift spaces, whereby each of the one or more drift spaces is arranged to be passed through multiple times by the ions and a drift time separation is maintained between the ions in the stages of inertial ion motion to increase ion mobility separation until desired level is achieved.

### Claim 14 (depends on 13)

An ion mobility spectrometer as claimed in claim 13 wherein each of the one or more inertial ion motion regions contains an ion mirror or deflector.

### Claim 15 (depends on 14)

An ion mobility spectrometer as claimed in claim 14 wherein the pressure in the inertial ion motion region(s) is such that separation of the ions according to their ion mobility does not occur in such region(s) but separation occurs that is independent of ion cross section but dependent on mass-to-charge ratio (m/z).

### Claim 16 (depends on 14)

A ion mobility spectrometer as claimed in claim 14 wherein the ion mirror or deflector provides a non-linear electric field to reflect or deflect ions.

### Claim 17 (depends on 16)

A ion mobility spectrometer as claimed in claim 16 wherein the non-linear electric field provides time of flight focusing of ions.

### Claim 18 (depends on 14)

An ion mobility spectrometer as claimed in claim 14 wherein the ion mirror or ion deflector is for receiving ions that have passed through the drift space in a first direction and reflecting or deflecting the ions back into the drift space to pass through the drift space in a second direction opposite to the first direction.

### Claim 19 (depends on 18)

An ion mobility spectrometer as claimed in claim 18 wherein the ion mirror or deflector is a first ion mirror or deflector and the spectrometer further comprises a second ion mirror or deflector for receiving ions that have passed through the drift space in the second direction and reflecting or deflecting the ions back into the drift space to pass through the drift space in the first direction again.

### Claim 20 (depends on 19)

An ion mobility spectrometer as claimed in claim 19 wherein the two mirrors or deflectors constitute two opposing ion mirrors or deflectors located adjacent the opposite ends of the drift space, whereby the ions may be repeatedly reflected or deflected between the ion mirrors or deflectors passing through the drift space between each reflection or deflection.

### Claim 21 (depends on 13)

An ion mobility spectrometer as claimed in claim 13 wherein the drift space is contained within a multipole.

### Claim 22 (depends on 13)

An ion mobility spectrometer as claimed in claim 13 wherein in use the drift space is filled with a buffer gas and the one or more inertial ion motion regions are held at high vacuum.

### Claim 23 (depends on 13)

An ion mobility spectrometer as claimed in claim 13 further comprising an ion storage device upstream of the drift space for storing ions from the ion source prior to introducing them as a pulse of ions into the drift space.

### Claim 24 (depends on 23)

An ion mobility spectrometer as claimed in claim 23 wherein the upstream ion storage device is also for storing ions extracted from the drift space after ion mobility separation has taken place.

### Claim 25 (depends on 23)

An ion mobility spectrometer as claimed in claim 23 further comprising an ion storage device downstream of the drift space for storing ions extracted from the drift space after ion mobility separation has taken place.

### Claim 26 (depends on 23)

An ion mobility spectrometer as claimed in claim 23 further comprising a mass analyzer for mass analyzing ions extracted from the drift space after ion mobility separation has taken place.