Ion mobilty spectrometer incorporating an ion guide in combination with an MS device
First Claim
1. A spectrometer comprising:
- an ion mobility spectrometer (IMS) device, for use in promoting separation of ions based on different mobility characteristics, the ion mobility spectrometer device comprising;
an inlet for ions;
an ion mobility section for receiving ions from the ion inlet;
means for forming an axial DC field within the pan mobility section, to generate a potential gradient along the axis thereof;
means for maintaining a gas at a desired pressure within the mobility section, whereby ions traveling through the mobility section under the influence of potential gradient are subject to collision with the gas, promoting separation based on differing mobility characteristics;
an ion focusing section including an RF ion guide having an axis, and means for supplying an RF voltage to the RF guide, to generate a field to promote focusing of ions along the axis of the RF ion guide, the ion mobility section being one of upstream from and internal with the ion focusing section; and
at least one mass analysis section, providing a final mass analysis section, for receiving ions from the RF ion guide and for separating ions based on differing mass-to-charge characteristics.
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Abstract
A hybrid mass spectrometer comprises an ion mobility (IMS) section and a mass analysis section that analyses ions based on mass-to-charge ratios. In the IMS section, a DC potential gradient is established and a drift gas provided, so as to separate ions based on varying ion mobilities. Additionally, at least a downstream portion of the IMS section includes a rod set focusing ions along the axis, this prevents loss of ions and gives good transfer of ions into-a-mass analysis section, which can be a time-of-flight mass analyzer or an analyzer including a quadrupole rod set. A collision cell and mass analyzer can be provided between the two sections for MS/MS analysis. The IMS section then provides better utilization of an available sample; as each group of ions is elected from the IMS section, one ion can be mass selected as a precursor, for subsequent fragmentation/reaction and subsequent mass analysis of the product ions. Another aspect of the invention provides the ability to form potential wells, utilizing a segmented rod set configuration, so as to trap and hold ions after separation based on mobility characteristics.
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Citations
43 Claims
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1. A spectrometer comprising:
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an ion mobility spectrometer (IMS) device, for use in promoting separation of ions based on different mobility characteristics, the ion mobility spectrometer device comprising;
an inlet for ions;
an ion mobility section for receiving ions from the ion inlet;
means for forming an axial DC field within the pan mobility section, to generate a potential gradient along the axis thereof;
means for maintaining a gas at a desired pressure within the mobility section, whereby ions traveling through the mobility section under the influence of potential gradient are subject to collision with the gas, promoting separation based on differing mobility characteristics;
an ion focusing section including an RF ion guide having an axis, and means for supplying an RF voltage to the RF guide, to generate a field to promote focusing of ions along the axis of the RF ion guide, the ion mobility section being one of upstream from and internal with the ion focusing section; and
at least one mass analysis section, providing a final mass analysis section, for receiving ions from the RF ion guide and for separating ions based on differing mass-to-charge characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of separating ions based on ion mobility characteristics, the method comprising:
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(i) generating ions;
(ii) providing at least one drift region having an axis extending therealong and providing and maintaining a gas at a desired pressure in the drift region;
(iii) forming a DC potential gradient along the drift region;
(iv) supplying ions to the drift region, whereby ions are driven through the drift region by the potential gradient and ions tend to separate due to differing ion mobility characteristics;
(v) passing the ions through an RF ion guide and maintaining gas at a pressure in the RF guide sufficient to focus the ions along an axis of the RF ion guide; and
(vi) passing ions into a mass analyzer for mass analysis in dependence upon ion mass-to-charge ratios. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
(a) receiving ions from the drift region and initially applying a uniform potential gradient along the rod set;
(b) after ions are uniformly distributed along the length of the rod set according to their mobility, establishing a potential well structure to retain groups of ions in separate potential wells; and
(c) releasing ions separately from each potential w II for subsequent mass analysis.
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27. A method as claimed in claim 26, which includes providing all or part of the drift region within the multipole rod set.
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28. A method as claimed in claim 26 or 27, which includes reducing the gas pressure after establishing the potential wells, to increase ion life time in the potential wells.
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29. A spectrometer comprising:
- an ion mobility spectrometer device, for use on promoting separation of ions based on different mobility characteristics, the ion mobility spectrometer device comprising
an inlet for ions;
a drift region;
means for forming a DC field along the drift region, to generate a potential gradient along the drift region; and
means for maintaining a gas pressure within the drift region, whereby ions traveling through the drift region under the influence of a potential gradient are subject to collision with a gas, promoting separation based on differing ion mobility characteristics;
a collision cell connected to the ion mobility spectrometer for receiving ions therefrom and including a gas therein, for promoting at least one of fragmentation of ions and reaction of the ions with ambient gas, to form product ions;
an RF ion guide having an axis, and means for supplying an RF voltage to the RF guide, to generate a field to promote focusing of ions along the axis of the RF ion guide, and a final mass analysis section for analyzing the product ions received from the RF ion guide. - View Dependent Claims (30, 31, 32, 43)
(i) a ring guide section comprising a plurality of axially aligned rings a power supply connected to the rings for generating the DC field within the drift region, the means for supplying an RF voltage being connected to the rings;
(ii) a multipole rod set including means for establishing a potential gradient along th rod s t, the means for supplying an RF voltage being connected to the rod set; and
(iii) a conductive cylinder.
- an ion mobility spectrometer device, for use on promoting separation of ions based on different mobility characteristics, the ion mobility spectrometer device comprising
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32. A spectrometer as claimed in claim 29, 30 or 31 wherein the collision cell includes at least one at a segmented multipole rod set and means for applying varying DC voltages to the multipole rod set, Thereby to generate a DC field within the rod set and a potential gradient along the collision cell, to promote travel of ions through the collision cell;
- and a ring guide comprising a plurality of rings, the collision cell further including an RF power supply for the multipole rod set and the ring guide.
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43. A spectrometer as claimed in claim 29 wherein the collision cell comprises the RF ion guide.
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33. A method for separating ions based on ion mobility characteristics, the method comprising:
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(i) generating ions;
(ii) providing a drift region having an axis extending there along;
(iii) forming a DC gradient along the drift region;
(iv) supplying ions to the drift region, whereby ions are driven through the drift region by the potential gradient, thereby to promote ion separation due to differing ion mobility characteristics;
(v) passing the ions into a collision cell to promote at least one of fragmentation and reaction with a collision gas, thereby to generate product ions;
(vi) passing the ions through an RF ion guide and maintaining gas at a pressure in the RF guide sufficient to focus the ions along an axis of the RF ion guide; and
(vii) subjecting the product ions to mass analysis. - View Dependent Claims (34, 35, 36, 37, 41, 42)
providing a non-linear potential gradient along the drift region, whereby the potential gradient at an end of the drift region promotes elution of ions at a desired rate.
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37. A method as claimed in claim 36, which includes, as different ions elute from the IMS drift region, switching the precursor ions selected by the first mass analyzer to correspond to an ion peak eluting from the drift region, thereby to maximize utilization of ions from a sample and enable sequential analysis of a plurality of different precursor ions present in the sample.
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41. A method as claimed in claim 33, which includes at least one of:
varying the potential gradient along the drift region with respect to time, thereby to vary the rate at which ions elute from the drift region; and
providing a non-linear potential gradient along the drift region, whereby the potential gradient at an end of the drift region promotes elution of ions at a desired rate.
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42. A method as claimed in claim 33 wherein the ion undergo steps (v) and (vi) concurrenty.
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38. A method of separating ions based on ion mobility characteristics, the method comprising:
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(i) generating ions;
(ii) providing at least one drift region having an axis extending therealong and providing and maintaining a gas at a desired pressure in the drift region;
(iii) forming a DC potential gradient along the drift region;
(iv) supplying ions to the drift region, whereby ions are driven through the drift region by the potential gradient and ions tend to separate due to differing ion mobility characteristics;
(v) passing ions into a mass analyzer for mass analysis in dependence upon ion mass-to-charge rations; and
(vi) adjusting parameters of the mass analyzer to follow changes in properties of ions eluting from the drift region. - View Dependent Claims (39, 40)
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Specification