US5479012A
Expired / Lapsed
US
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Method of space charge control in an ion trap mass spectrometer
Assignee: Agilent Technologies Inc
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Filing: 1994-01-10
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Granted: 1995-12-26
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Expires: 2014-01-10
Abstract
Abstract A method of using a quadrupole ion trap mass spectrometer for high resolution mass spectroscopy is disclose. In the preferred embodiment, the space charge in the ion trap is controlled with high accuracy. The mass spectrum to be analyzed is divided into a plurality of contiguous mass segments and each of the segments is separately scanned. To control space charge, a broadband supplemental waveform is applied to the ion trap during the ionization period for each segment, the broadband signal being construct to eliminate all unwanted ions from the ion trap by resonance ejection such that only those ions having masses within the desired mass segment remain in the ion trap. Preferably, the ionization of each mass segment is performed under identical trapping conditions, and the ionization parameters for each segment is adjusted to optimize the space charge in the trap for that particular segment. Conveniently, the adjustment of ionization parameters may be based on the previous analytical scan of the same mass segment.
Inventors
- 👤 Gregory J. Wells
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:43
CPC Classifications
H; H01; H01J; H01J49/00; H01J49/26; H01J49/34; H01J49/42; H01J49/426; H01J49/4265; H01J49/0027; H01J49/0031; H01J49/4205; H01J49/424
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
165 words
A method of using a quadrupole ion trap mass spectrometer to detect the presence of any ions within a range of interest comprising the steps of: (a) establishing a trapping field within the ion trap such that ions in said range of interest are stably held within the ion trap; (b) introducing sample ions into the ion trap; (c) isolating ions within a first mass range within said ion trap, said first mass range containing masses fewer than said range of interest; (d) detecting the masses stored within the ion trap within said first mass range; (e) substantially immediately thereafter introducing additional sample ions into the ion trap; (f) isolating ions within a second mass range within said ion trap, said second mass range covering a range of masses substantially different than said first mass range; and, (g) detecting the masses stored within said ion trap within said second mass range, such that a mass spectrum of said first and second mass ranges is obtained.
Claim 2
Independent Claim
165 words
A method of using a quadrupole ion trap mass spectrometer to detect the presence of any ions within a range of interest comprising the steps of: (a) establishing a trapping field within the ion trap such that ions in said range of interest are stably held within the ion trap; (b) introducing sample ions into the ion trap; (c) isolating ions within a first mass range within said ion trap, said first mass range containing masses fewer than said range of interest; (d) detecting the masses stored within the ion trap within said first mass range; (e) substantially immediately thereafter introducing additional sample ions into the ion trap; (f) isolating ions within a second mass range within said ion trap, said second mass range covering a range of masses substantially different than said first mass range; and, (g) detecting the masses stored within said ion trap within said second mass range, such that a mass spectrum of said first and second mass ranges is obtained.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein the trapping field parameters are substantially the same during each ion isolation step.
Claim 4
Dependent Claim
41 words
The method of claim 1 wherein the ionization parameters used in each step of introducing sample ions into the ion trap are independently determined based on the expected ion population within the mass range that is isolated within the ion trap.
Claim 5
Dependent Claim
22 words
The method of claim 3 wherein the ionization parameters are adjusted based on the prior analytical scan of the same mass range.
Claim 6
Independent Claim
113 words
A method of using a quadrupole ion trap mass spectrometer comprising the steps of: (a) establishing an initial trapping field in said ion trap capable of stably trapping ions having masses in a selected range within the ion trap; (b) dividing said selected range of masses into a plurality of substantially contiguous mass segments; (c) sequentially isolating the masses within each mass segment in said ion trap using broadband supplemental waveforms, each said supplemental broadband waveform having frequency components that will cause ions outside of a selected mass segment to be resonantly ejected from the ion trap; (d) obtaining a mass spectrum of each mass segment prior to isolating the next mass segment.
Claim 7
Independent Claim
113 words
A method of using a quadrupole ion trap mass spectrometer comprising the steps of: (a) establishing an initial trapping field in said ion trap capable of stably trapping ions having masses in a selected range within the ion trap; (b) dividing said selected range of masses into a plurality of substantially contiguous mass segments; (c) sequentially isolating the masses within each mass segment in said ion trap using broadband supplemental waveforms, each said supplemental broadband waveform having frequency components that will cause ions outside of a selected mass segment to be resonantly ejected from the ion trap; (d) obtaining a mass spectrum of each mass segment prior to isolating the next mass segment.
Claim 8
Dependent Claim
17 words
The method of claim 5 wherein each mass segment is isolated using the same trapping field conditions.
Claim 9
Dependent Claim
15 words
The method of claim 5 wherein the mass segments cover mass ranges of different size.
Claim 10
Dependent Claim
15 words
The method of claim 5 wherein said mass spectra are obtained using resonance ejection scanning.
Claim 11
Dependent Claim
15 words
The method of claim 5 wherein said mass spectra are obtained using mass instability scanning.
Claim 12
Dependent Claim
14 words
The method of claim 5 wherein said mass spectra are obtained using internal detection.
Claim 13
Dependent Claim
15 words
The method of claim 10 wherein said mass spectra are obtained by measuring induced currents.
Claim 14
Dependent Claim
35 words
The method of claim 5 wherein said mass spectra are obtained by simultaneously ejecting from the ion trap all ions within a particular mass segment and detecting the time of flight of the ejected ions.
Claim 15
Dependent Claim
20 words
The method of claim 5 wherein the ionization parameters used during the ionization of each mass segment are separately determined.
Claim 16
Dependent Claim
26 words
The method of claim 13 wherein the ionization parameters used for a particular mass segment are based on the previous scan of the same mass segment.
Claim 17
Dependent Claim
65 words
The method of claim 5 wherein the mass range of the mass segments is chosen such that at least one relatively low concentration sample ion of interest is within one segment and another relatively high concentration ion is in a different segment, such that the space charge from said high concentration ion does not interfere with the analysis of said low concentration ion of interest.
Claim 18
Independent Claim
108 words
A method of using a quadrupole ion trap mass spectrometer comprising the steps of: (a) establishing a set of predetermined trapping conditions that will efficiently trap ions having masses spanning a first range of masses; (b) dividing said first range of masses into a plurality of contiguous mass segments; (c) consecutively isolating and obtaining mass spectra of each of the mass segments; (d) integrating the mass spectra of each mass segment to determine the total ion population within that mass segment; and, (e) repeating step (c) using the integrated total ion population of each mass segment to control an ionization parameter used in connection with said mass segment.
Claim 19
Independent Claim
108 words
A method of using a quadrupole ion trap mass spectrometer comprising the steps of: (a) establishing a set of predetermined trapping conditions that will efficiently trap ions having masses spanning a first range of masses; (b) dividing said first range of masses into a plurality of contiguous mass segments; (c) consecutively isolating and obtaining mass spectra of each of the mass segments; (d) integrating the mass spectra of each mass segment to determine the total ion population within that mass segment; and, (e) repeating step (c) using the integrated total ion population of each mass segment to control an ionization parameter used in connection with said mass segment.
Claim 20
Dependent Claim
20 words
The method of claim 16 wherein the step of isolating each mass segment is performed using said predetermined trapping conditions.
Claim 21
Dependent Claim
67 words
The method of claim 17 wherein the step of isolating each mass segment comprises the step of applying a broadband supplemental voltage to the ion trap while ions are being formed within the ion trap, said supplemental broadband voltage having the characteristic that it will resonantly eject all masses within said mass range out of the ion trap other than those within the mass segment being isolated.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-12-25 | 1999-06-26 | 1999-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-25 | 2003-06-26 | 2003-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-25 | 2007-06-26 | 2007-12-26 | $7700.00 | Window Closed / Lapsed |