# US 8,772,711 B1 · Apparatus and method of dissociating ions in a multipole ion guide

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- Number: US 8,772,711 B1
- Document ID: US8772711B1
- Status: Granted
- Kind: B1
- Application number: 14/011,529
- Filed: 2013-08-27
- Granted: 2014-07-08
- Earliest claimed: 2013-08-27
- Assignees: Battelle Memorial Institute
- Applicants: Ian K. Webb; Keqi Tang; Richard D. Smith; Yehia M. Ibrahim; Gordon A. Anderson
- Inventors: Ian K. Webb; Keqi Tang; Richard D. Smith; Yehia M. Ibrahim; Gordon A. Anderson
- Web page: https://patentgrep.com/patent/US8772711B1

## CPC

- H01J 49/063: {Multipole ion guides, e.g. quadrupoles, hexapoles}
- H01J 49/0063: {by applying a resonant excitation voltage}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

A method of dissociating ions in a multipole ion guide is disclosed. A stream of charged ions is supplied to the ion guide. A main RF field is applied to the ion guide to confine the ions through the ion guide. An excitation RF field is applied to one pair of rods of the ion guide. The ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions. The multipole ion guide is, but not limited to, a quadrupole, a hexapole, and an octopole.

## Claims

### Claim 1

A method of dissociating ions in a multipole ion guide comprising:
a. supplying a stream of charged ions to the ion guide;
b. applying a main radio frequency (RF) field to the ion guide to confine the ions through the ion guide; and
c. applying an excitation RF field of an antiphase waveform to one pair of rods of the ion guide, wherein the ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions.

### Claim 2 (depends on 1)

The method of claim 1 wherein the multipole ion guide is at least one of the following: a quadrupole, a hexapole, and an octopole.

### Claim 3 (depends on 1)

The method of claim 1 wherein the charged ions are injected into the ion guide from an ion mobility drift cell.

### Claim 4 (depends on 3)

The method of claim 3 further comprising providing a Brubaker lens, coupled between the ion mobility drift cell and the ion guide, for focusing of the ions into the ion guide.

### Claim 5 (depends on 1)

The method of claim 1 wherein the excitation RF field is synchronized with an arrival time of the ions.

### Claim 6 (depends on 1)

The method of claim 1 wherein the dissociation of the ions occurs within specific ion mobility separation ranges.

### Claim 7 (depends on 1)

The method of claim 1 wherein the ions are dissociated while any dissociated ions are left intact.

### Claim 8 (depends on 7)

The method of claim 7 wherein the dissociated ions are not excited.

### Claim 9 (depends on 1)

The method of claim 1 wherein the ion guide operates in a pressure range from about 1E-6 to about 1E-2 torr.

### Claim 10 (depends on 1)

The method of claim 1 wherein the applying the excitation RF field to one pair of rods of the ion guide comprises applying the excitation RF field to a single rod of the one pair of rods of the ion guide.

### Claim 11

An apparatus for dissociating ions comprising:
a. a multipole ion guide for receiving a stream of charged ions;
b. a main RF field source, coupled to the ion guide, for confining the ions through the ion guide;
c. an excitation RF field source coupled to one pair of rods of the ion guide, wherein the ions undergo dissociation when the applied excitation RF field of an antiphase waveform is resonant with a secular frequency of the ions.

### Claim 12 (depends on 11)

The apparatus of claim 11 wherein the multipole ion guide is at least one of the following: a quadrupole, a hexapole, and an octopole.

### Claim 13 (depends on 11)

The apparatus of claim 11 further comprising an ion mobility drift cell for injecting the charged ions into the ion guide.

### Claim 14 (depends on 13)

The apparatus of claim 13 further comprising a Brubaker lens, coupled between the ion mobility drift cell and the ion guide, for focusing of the ions into the ion guide.

### Claim 15 (depends on 11)

The apparatus of claim 11 further comprising a transformer with a primary winding coupled to the excitation RF field source and a secondary winding coupled to the main RF field source.

### Claim 16 (depends on 11)

The apparatus of claim 11 wherein the ion guide operates in a pressure range from about 1E-6 to about 1E-2 torr.

### Claim 17

A method of dissociating ions in a quadrupole ion guide comprising:
a. supplying a stream of charged ions to the ion guide;
b. applying a main radio frequency field to both pairs of rods of the ion guide to confine the ions through the ion guide; and
c. applying an excitation RF field of an antiphase waveform to one pair of rods of the ion guide, wherein the ions undergo dissociation when the applied excitation RF field is resonant with a secular frequency of the ions, and wherein dissociated ions are left intact and not excited.

### Claim 18 (depends on 17)

The method of claim 17 wherein the charged ions are injected into the ion guide from an ion mobility drift cell.

### Claim 19 (depends on 18)

The method of claim 18 further comprising providing a Brubaker lens, coupled between the drift cell and the ion guide, for focusing the ions into the ion guide.

### Claim 20 (depends on 17)

The method of claim 17 wherein the excitation RF field is synchronized with an arrival time of the ions.

### Claim 21 (depends on 17)

The method of claim 17 wherein the dissociation occurs within specific ion mobility separation ranges.

### Claim 22

An apparatus for dissociating ions comprising:
a. a quadrupole ion guide for receiving a stream of charged ions;
b. a main RF field source, coupled to both pairs of rods of the ion guide, for confining the ions through the ion guide;
c. an excitation RF field source coupled to one pair of rods of the ion guide; and
d. a transformer with a primary winding coupled to the excitation RF field source and a secondary winding coupled to the main RF field source, wherein the ions undergo dissociation when the excitation RF field of an antiphase waveform is resonant with a secular frequency of the ions, and wherein dissociated ions are left intact and not excited.

### Claim 23 (depends on 22)

The apparatus of claim 22 further comprising an ion mobility drift cell for injecting the charged ions into the ion guide.

### Claim 24 (depends on 23)

The apparatus of claim 23 further comprising a Brubaker lens, coupled between the ion mobility drift cell and the ion guide, for focusing of the ions into the ion guide.