# US 5,352,890 A · Quadrupole ion trap mass spectrometer having two axial modulation excitation input frequencies and method of parent and neural loss scanning

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- Number: US 5,352,890 A
- Document ID: US5352890A
- Status: Granted
- Kind: A
- Application number: 07/990,690
- Filed: 1992-12-14
- Granted: 1994-10-04
- Earliest claimed: 1991-01-25
- Assignees: University of Florida; Finnigan Corporation
- Inventors: Jodie V. Johnson; Randall E. Pedder; Richard A. Yost; Michael S. Story
- Web page: https://patentgrep.com/patent/US5352890A

## CPC

- H01J 49/424: {Three-dimensional ion traps, i.e. comprising end-cap and ring electrodes}
- H01J 49/0063: {by applying a resonant excitation voltage}
- H01J 49/0081: {Tandem in time, i.e. using a single spectrometer}
- H01J 49/427: {Ejection and selection methods}
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

There is described a method of operating an ion trap mass spectrometer. The method is carried out by trapping ions of selected masses in a three-dimensional field and then generating at least two fields in said trap having different frequencies to excite multiple trapped ions.

## Claims

### Claim 1

A mass spectrometry method including the steps of:
a. establishing a trapping field capable of trapping parent ions and daughter ions within a trap region bounded by a set of electrodes;
b. applying a low power supplemental AC voltage signal to the electrodes to induce dissociation of a first trapped parent ion, wherein the low power supplemental AC voltage signal has a first frequency matching a resonant frequency of the first trapped parent ion;
c. applying a high power supplemental AC voltage signal to the electrodes to resonate a first daughter ion to a degree sufficient to enable detection of the first daughter ion, wherein the high power supplemental AC voltage signal has a second frequency matching a resonant frequency of the first daughter ion, wherein the high power supplemental AC voltage signal resonates the first daughter ion to a degree sufficient for detection by a detector comprising, or integrally mounted with at least one of the electrodes; and
d. detecting the first daughter ion.

### Claim 2 (depends on 1)

The method of claim 1 wherein the trapping field is a three-dimensional quadrupole trapping field, and wherein step (a) includes the step of applying to the electrodes a fundamental voltage signal having a radio frequency component.

### Claim 3

A mass spectrometry method including the steps of:
a. establishing a trapping field capable of trapping parent ions and daughter ions within a trap region bounded by a set of electrodes;
b. applying a low power supplemental AC voltage signal to the electrodes to induce dissociation of a first trapped parent ion, wherein the low power supplemental AC voltage signal has a first frequency matching a resonant frequency of the first trapped parent ion; and
c. applying a high supplemental AC voltage signal to the electrodes to resonate a first daughter ion to a degree sufficient to enable detection of the first daughter ion, wherein the high power supplemental AC voltage signal has a second frequency matching a resonant frequency of the first daughter ion, wherein steps (b) and (c) are performed simultaneously.

### Claim 4

A mass spectrometry method including the steps of:
a. establishing a three-dimensional quadrupole trapping field capable of trapping parent ions and daughter ions within a trap region bounded by a set of electrodes, and trapping parent ions in the trap region;
b. then applying a low power supplemental AC voltage signal to the electrodes to induce dissociation of a first one of the parent ions to produce a first daughter ion, wherein the low power supplemental AC voltage signal has a first frequency matching a resonant frequency of the first one of the parent ions; and
c. while performing step (b), applying a high power supplemental AC voltage signal to the electrodes to resonate the first daughter ion to a degree sufficient to enable detection thereof, wherein the high power supplemental AC voltage signal has a second frequency matching a resonant frequency of the first daughter ion.

### Claim 5

A mass spectrometry method including the steps of:
a. establishing a three-dimensional quadrupole trapping field capable of trapping parent ions and daughter ions within a trap region bounded by a set of electrodes, and trapping parent ions in the trap region;
b. then applying a lower power supplemental AC voltage signal to the electrodes to induce dissociation of a first species of the parent ions to produce first daughter ions, wherein the low power supplemental AC voltage signal has a first frequency matching a resonant frequency of the first species of the parent ions;
c. while performing step (b), applying a high power supplemental AC voltage signal to the electrodes to resonate the first daughter ions to a degree sufficient to enable detection thereof, wherein the high power supplemental AC voltage signal has a second frequency matching a resonant frequency of the first daughter ions;
d. after step (b), varying the frequency of the low power supplemental AC voltage signal to induce dissociation of different ones of the parent ions; and
e. while performing step (d), continuing to apply said high power supplemental AC voltage signal to the electrodes to resonate daughter ions generated during step (d) to a degree sufficient to enable detection thereof.