Patent Grant
10068759
This invention is related to mass spectrometry and is particularly suitable for portable and/or compact high pressure mass spectrometers.
Mass spectrometry is a powerful tool for identifying and quantifying gas phase molecules. A mass spectrometry system has three fundamental components: an ion source, a mass analyzer and a detector. These components can take on different forms depending on the type of mass analyzer. Interest in portable mass spectrometry (MS) has increased due to potential uses where rapid in situ or field measurements may be of value. Conventional mass spectrometers are unsuitable for these situations because of their large size, weight, and power consumption (SWaP). See, e.g., Whitten et al., Rapid Commun. Mass Spectrom. 2004, 18, 1749-52.
There remains a need for portable, compact and light-weight mass spectrometers for chemical monitoring and analysis.
Some embodiments of the invention are directed to a mass spectrometer (HPMS). The HPMS can include at least one mass analyzer ion trap with an injector endcap electrode, a ring electrode and an ejector endcap electrode. The HPMS can also include a first chamber holding the ion trap mass analyzer. The first chamber can be configured to have a first background pressure P1 during operation. The first background pressure P1 can be a high background pressure of between about 0.1 Torr and 1000 Torr. The HPMS can also include a second chamber with a detector in fluid communication with and downstream, but adjacent, the first chamber. The second chamber can be configured to have a second background pressure P2 that is less than P1. A ratio of P2/P1 can be less than 1 and greater than about 0.1. P2/P1 can generate an increase in peak height in at least one detected ion signal of at least 30% measured using a test sample of mesitylene, with the at least one detected ion signal associated with an ion of the test sample, relative to when the first and second chambers are operated at a common pressure where P1=P2. The HPMS can also include at least one vacuum pump in communication with the first and/or second chambers for generating P1 and/or P2.
The mass analyzer and pressure ratio P2/P1 can be configured to generate convective flow of buffer gas with a Knudsen value Kn less than 10 to thereby generate gas flow and/or transport in a viscous or transition regime.
The ratio P1/P2 can selected to generate a detected ion signal with a peak height of ion intensity of an ion in a sample under analysis that is increased from a corresponding baseline peak intensity value obtained when P2=P1 by between 30% to about 200%, measured with respect to an ion or ions associated with the mesitylene test sample.
The ratio P2/P1 can be between about 0.9 and about 0.10, such as one of: 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, and about 0.10.
In some embodiments, one of P1 and P2 can be at 100 mTorr or above.
In some embodiments P2 is above 500 mTorr, and P1 is between 1 Torr and 10 Torr.
At least a perimeter portion of the ring electrode can be sealably attached to a corresponding perimeter portion of the ejector and/or the injector endcap electrode to define a sealed space therebetween to thereby block incoming buffer gas.
The HPMS can include a buffer and sample gas inlet that is in fluid communication with the first chamber and allows a sample and buffer gas to enter the first chamber.
The injector endcap electrode and the ejector endcap electrode can both be sealably attached to the ring electrode to define a respective sealed space therebetween whereby incoming buffer gas is primarily only allowed through one or more apertures extending axially through the injector endcap electrode.
The HPMS can include a solid, gas-impermeable wall or partition separating the first and second chambers, with the ion trap directly or indirectly sealably attached thereto. The internal wall or partition can have at least one axially extending flow path channel aligned with the ejector endcap aperture or apertures to direct a mass flux of buffer gas to the second chamber.
Other embodiments are directed to high-pressure mass spectrometers (HPMS). A respective HPMS can include at least one mass analyzer ion trap. The mass analyzer ion trap can include an injector endcap electrode, a ring electrode and an ejector endcap electrode. At least a perimeter portion of the ring electrode can be sealably attached to a corresponding perimeter portion of the injector electrode and/or the ejector electrode to define a sealed space therebetween to thereby block incoming buffer gas. The HPMS can also include a first chamber or sub-chamber holding the ion trap mass analyzer. The first chamber or sub-chamber can be configured to have a first background pressure P1 during operation, the first background pressure P1 being a high background pressure. The HPMS can also include a second chamber or sub-chamber with a detector in fluid communication with and downstream, but adjacent, the first chamber or sub-chamber. The second chamber or sub-chamber can be configured to have a second background pressure P2 that is less than P1.
A ratio of P2/P1 can be less than 1 and greater than about 0.1. The mass analyzer and pressure ratio P2/P1 can be configured to generate convective flow of buffer gas with a Knudsen value Kn less than 10 to thereby generate gas transport and/or flow in a viscous regime.
The injector endcap electrode and the ejector endcap electrode can both be sealably attached to the ring electrode to define a respective sealed space therebetween whereby incoming buffer gas is primarily allowed through one or more apertures extending axially through the injector endcap electrode.
The sealed space of the ring and endcap electrode can have a leak rate of no more than 10% of an average gas flow rate through the mass analyzer.
The ratio P2/P1 can generate an increase in peak height in at least one detected ion signal of at least 30% relative to when the first and second chambers or sub-chambers are operated at a common pressure, with the at least one detected ion signal associated with an ion of the test sample.
In some embodiments, P1 is at or above 50 mTorr or at or above 100 mTorr.
In some embodiments, P2 can be above 500 mTorr and P1 can be between 1 Torr and 10 Torr.
The HPMS can include a gas impermeable, electrically insulating sealant that surrounds an axially extending ring electrode through-aperture or apertures, residing between the ring electrode and the ejector endcap electrode and/or residing between the injector endcap electrode and the ring electrode to provide the sealed attachment.
The HPMS can include a mounting fixture holding the ion trap inside the first and/or second chamber or sub-chamber housing. The mounting fixture can have a planar surface with an axially extending open channel residing downstream of the ion trap. The planar surface can abut an inwardly extending ledge of a housing holding the first and/or second chamber or sub-chamber.
The HPMS can include a mounting fixture holding the ion trap inside the first and/or second chamber or sub-chamber. The mounting fixture can have a planar surface residing upstream of the ion trap that can hold the ion trap against a wall or partition separating the first and second chambers or sub-chambers.
The HPMS can include a solid, gas-impermeable wall or partition separating the first and second chambers or sub-chambers, with the ion trap directly or indirectly sealably attached thereto. The internal wall or partition can have at least one axially extending flow path channel aligned with the ejector endcap aperture or apertures to direct mass flux buffer gas to the detector.
The HPMS can include a housing. The first chamber or sub-chamber can be a first chamber and the second chamber or sub-chamber can be a second chamber that resides adjacent the first chamber. The HPMS can also include an electron ionizer inside the first chamber or in fluid communication with the first chamber, residing upstream of the mass analyzer. The mass analyzer can be closely spaced apart from the detector to reside within a distance of between about 1 mm to about 10 mm thereof. The ion trap mass analyzer can be either: (a) a CIT with critical dimensions r0 or z0 less than about 1 mm; or (b) a Stretched Length Ion Trap (SLIT) with the ring electrode having an aperture which extends along a longitudinal direction and the central electrode surrounds the aperture in a lateral plane perpendicular to the longitudinal direction to define a transverse cavity for trapping charged particles. The aperture in the ring electrode can be elongated in the lateral plane and may have a ratio of a major dimension to a minor dimension that is greater than 1.5.
In some embodiments, the pressure P1 can be between 1 Torr and 10 Torr. The ratio P1/P2 can be selected to generate peak heights of ion intensity of a respective ion in a sample under analysis that are increased from baseline peak intensity value obtained when P2=P1 by between about 30% to about 200%, measured using an ion associated with a test sample comprising mesitylene.
The HPMS can include at least one vacuum pump in fluid communication with at least one of the first chamber or sub-chamber or the second chamber or sub-chamber.
The HPMS can include a buffer gas and sample inlet in fluid communication with the first chamber. The first chamber or sub-chamber can be a first chamber and the second chamber or sub-chamber can be a second chamber that resides adjacent the first chamber. The HPMS can include a single vacuum pump attached to a vacuum port on the second chamber and can be configured to also generate the high pressure of P1 using a manifold and valve in communication with the vacuum pump in cooperation with control of pressure associated with the buffer gas and sample entry into the inlet.
Yet other embodiments are directed to a mass spectrometer (HPMS) that includes: at least one mass analyzer ion trap with an injector endcap electrode, a ring electrode and an ejector endcap electrode and a first chamber or sub-chamber comprising the ion trap mass analyzer. The first chamber or sub-chamber is configured to have a first background pressure P1 during operation, the first background pressure P1 being a high background pressure of between about 0.1 Torr and 1000 Torr. The HPMS also includes a second chamber or sub-chamber with a detector in fluid communication with and downstream, but adjacent, the first chamber. The second chamber or sub-chamber can be configured to have a second background pressure P2 that is less than P1, wherein a ratio of P2/P1 is between 0.9 and about 0.1. The HPMS also includes at least one vacuum pump in communication with the first and/or second chambers or sub-chambers for generating P1 and/or P2.
The ratio P2/P1 can be one of: 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, and about 0.10 and can generate an increase in peak height in at least one detected ion signal of at least 30% relative to when the first and second chambers or sub-chambers are operated at a common pressure where P1=P2, measured using an ion associated with a test sample comprising mesitylene.
Still other embodiments are directed to methods of operating a high pressure mass spectrometers to enhance signals detected by an onboard detector. The methods include: (a) providing a pressure mass spectrometer with an ion trap mass analyzer and detector, wherein the ion trap mass analyzer comprises a ring electrode with at least one aperture extending therethrough, an injector endcap with at least one aperture extending therethrough and an ejector endcap electrode with at least one aperture extending therethrough; (b) generating a first background pressure P1 about the ion trap mass analyzer, wherein P1 is greater than 0.01 Torr; (c) generating a second background pressure P2 about the detector, wherein 0.1<P2/P1<1; and (d) generating at least one enhanced ion peak with an increase in peak height of at least 30% in detected signal relative to when P2=P1, as measured using an ion associated with a test sample of mesitylene.
The ion trap mass analyzer and pressure ratio P2/P1 can be configured to generate a convective flow of buffer gas with a Knudsen value (Kn) less than 10 to thereby generate gas flow and/or transport in a viscous regime.
The ion trap mass analyzer can include a sealant between the ring electrode and at least one of the injector endcap electrode and the ejector endcap electrode. The sealant can be configured to surround the ring electrode at least one aperture and the respective ejector endcap at least one aperture.
The method can include generating convective flow of buffer gas using the mass analyzer and P2/P1 and P2 can be between 10 mTorr to 900 mTorr.
The ratio P2/P1 can be less than 1 and equal to or greater than about 0.1.
The ring electrode can be sealably attached to both the ejector and injector endcap electrodes and gas flow and/or ion transport can primarily only through the electrode apertures.
The method can include generating convective flow of buffer gas using the mass analyzer and P2/P1. P1 can be between about 1 Torr and 10 Torr and P2/P1 can be between 0.9 and about 0.1, such as one of 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, and 0.10.
The ion trap can be a microscale ion trap.
Yet other aspects are directed to a high-pressure mass spectrometer (HPMS) that includes: a housing and a first chamber or sub-chamber held by the housing having at least one sample and/or buffer gas inlet port; at least one mass analyzer microscale ion trap with an injector endcap electrode, a ring electrode and an ejector endcap electrode held in the first chamber or sub-chamber. The first chamber or sub-chamber is configured to have a first background pressure P1 during operation, the first background pressure P1 being a high background pressure of between about 0.1 Torr and 10 Torr. The HPMS can also include an ionizer held by the housing in fluid communication with the at least one mass analyzer ion trap; a second chamber or sub-chamber held by the housing comprising a detector in fluid communication with and downstream, but adjacent, the first chamber; and at least one vacuum pump in communication with the first and second chambers or sub-chambers. The second chamber or sub-chamber is configured to have a second background pressure P2 that is less than P1. A ratio of P2/P1 is less than 1 and greater than 0.1. The ratio P2/P1 generates an increase in peak height in at least one detected ion signal of at least 30% relative to when the first and second chambers are operated at a common pressure where P1=P2, measured using an ion associated with a test sample of mesitylene.
At least a perimeter portion of the ring electrode can be sealably attached to a corresponding perimeter portion of at least one of the injector endcap or ejector endcap electrodes to define a sealed space therebetween to thereby block incoming buffer gas.
The at least one vacuum pump can be a single vacuum pump attached to a vacuum port in the second chamber.
Other aspects of the invention are directed to microscale mass analyzer ion traps. The microscale traps include an injector endcap electrode, a ring electrode and an ejector endcap electrode. At least a perimeter portion of the ring electrode can be sealably attached to a corresponding perimeter portion of at least one of the ejector or injector electrodes to define a sealed space therebetween to thereby block incoming buffer gas from entering through perimeter spaces in operation.
The injector endcap electrode and the ejector endcap electrode can both be sealably attached to the ring electrode to define a respective sealed space therebetween whereby, in position in a mass spectrometer, incoming buffer gas can primarily be allowed through one or more apertures extending axially through the injector endcap electrode.
The sealed space of the ring and endcap electrode can have a leak rate of no more than 10% of an average gas flow rate through the ion trap during normal operation in a high background pressure chamber.
The ion trap mass analyzer can be either: (a) a CIT with critical dimensions r0 or z0 less than about 1 mm; or (b) a Stretched Length Ion Trap (SLIT) with the ring electrode having an aperture which extends along a longitudinal direction and the central electrode surrounds the aperture in a lateral plane perpendicular to the longitudinal direction to define a transverse cavity for trapping charged particles. The aperture in the ring electrode can be elongated in the lateral plane.
Optionally, the SLIT aperture can have a ratio of a major dimension to a minor dimension that is greater than 1.5.
The mass analyzer can operate with a pressure differential across the sealed ion trap so that pressure outside the injector electrode has a background pressure P1 during operation. The first background pressure P1 can be a high background pressure of between about 0.01 Torr and 1000 Torr. Pressure outside the ejector electrode can be at a second background pressure P2 that is less than Pl. A ratio of P2/P1 can be less than 1 and greater than 0.1. The ratio P2/P1 can be one of about 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, and about 0.10. The ratio P2/P1 can generate an increase in peak height in at least one detected ion signal of at least 30% measured using a test sample of mesitylene, with the at least one detected ion signal associated with an ion of the test sample, relative to when the first and second chambers are operated at a common pressure where P1=P2.
It is noted that aspects of the invention described with respect to one embodiment, may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. Applicant reserves the right to change any originally filed claim and/or file any new claim accordingly, including the right to be able to amend any originally filed claim to depend from and/or incorporate any feature of any other claim or claims although not originally claimed in that manner. These and other objects and/or aspects of the present invention are explained in detail in the specification set forth below. Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments that follow, such description being merely illustrative of the present invention.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.
The present invention will now be described more fully hereinafter with reference to the accompanying figures, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like numbers refer to like elements throughout. In the figures, certain layers, components or features may be exaggerated for clarity, and broken lines illustrate optional features or operations unless specified otherwise. In addition, the sequence of operations (or steps) is not limited to the order presented in the figures and/or claims unless specifically indicated otherwise. In the drawings, the thickness of lines, layers, features, components and/or regions may be exaggerated for clarity and broken lines illustrate optional features or operations, unless specified otherwise.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms, “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and/or “including” when used in this specification, specify the presence of stated features, regions, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.”
It will be understood that when a feature, such as a layer, region or substrate, is referred to as being “on” another feature or element, it can be directly on the other feature or element or intervening features and/or elements may also be present. In contrast, when an element is referred to as being “directly on” another feature or element, there are no intervening elements present. It will also be understood that, when a feature or element is referred to as being “connected”, “attached” or “coupled” to another feature or element, it can be directly connected, attached or coupled to the other element or intervening elements may be present. In contrast, when a feature or element is referred to as being “directly connected”, “directly attached” or “directly coupled” to another element, there are no intervening elements present. Although described or shown with respect to one embodiment, the features so described or shown can apply to other embodiments.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the present application and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.
Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, the terms “upwardly”, “downwardly”, “vertical”, “horizontal” and the like are used herein for the purpose of explanation only unless specifically indicated otherwise.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
The term “about” with respect to a numerical value means that the stated number can vary from that value by +/−10%.
The term “analyte” refers to a molecule or chemical(s) in a sample undergoing analysis. The analyte can comprise chemicals associated with any industrial products, processes or environments or environmental hazards, toxins such as toxic industrial chemicals or toxic industrial materials, organic compounds, and the like. Moreover, analytes can include biomolecules found in living systems or manufactured such as biopharmaceuticals.
The term “buffer gas” refers to any gas or gas mixture that has neutral atoms such as air, nitrogen, helium, hydrogen, argon, and methane, by way of example.
The term “mass resonance scan time” refers to mass selective ejection of ions from the ion trap with associated integral signal acquisition time.
The term “mass” is often inferred to mean mass-to-charge ratio and its meaning can be determined from context. When this term is used when referring to mass spectra or mass spectral measurements, it is implied to mean mass-to-charge ratio measurements of ions.
The terms “convective” when used with “gas flow” refers to a flow of buffer gas through the ring electrode of an ion trap mass analyzer, typically a microscale ion trap, operated at high background pressure so that the convective flow of buffer gas is in a viscous (continuum or transitional) gas flow regime to transport analyte molecules/ions for analysis. The convective gas flow may optionally also, or alternatively, include a convective gas flow transport of ions. The analyte molecules in the flow of buffer gas into/through the ion trap mass analyzer is a minority component as is well known to those of skill in the art. The convective gas flow and/or transport described herein for some embodiments of the invention has a Knudsen number (Kn) that is 10 or below, and in some embodiments, near unity or smaller. Kn is a ratio of the mean free path length of the molecules of a fluid or gas to a characteristic length used to describe the important length scale of an experiment. By way of comparison, Kn>1 is associated with free molecular gas flow.
The term “microscale” with respect to ion trap mass analyzers refers to miniature sized ion traps with a critical dimension that is in the millimeter to submillimeter range, typically with associated apertures in one or more electrodes of the ion trap having a critical dimension between about 0.001 mm to about 5 mm, and any sub-range thereof. The ion trap electrode central aperture can take on different geometries such as a cylindrical or slit shaped void and arrays of voids are possible.
Mass spectrometry has historically been performed under conditions of high vacuum. The reason for this condition is that performance is enhanced if ions do not collide with background gas molecules during their trajectory from an ion source through a mass analyzer arriving at a detector. Ion-molecule collision events scatter the ions away from their intended trajectory, often degrading mass resolution and signal strength. The vacuum that achieves sufficient resolution in conventional systems can be formalized through the Knudsen number, Kn. Mass spectrometry is typically performed in the molecular flow regime defined as Kn>1, and in conventional practice, Kn is between about 100 and over 10,000 for conventional mass spectrometry systems.
Table 1 below includes the calculated mean free path (mfp) for helium and nitrogen at a range of pressures from 10−6-760 Torr. Collision cross sections for helium and nitrogen are determined from the van der Walls volumes of each and average collisional radii used in the mfp calculations are 0.14 nm and 0.18 nm respectively. See, e.g., Knapman, et al, Intl. I. Mass Spectrom., 2010, 298, 17-23, the contents of which are hereby incorporated by reference as if recited in full herein. The mfp values were calculated from Equation 1 where k is Boltzmann's constant, T is temperature in Kelvin, d is the collision diameter, and P is the gas pressure. A temperature of 300K is assumed in Table 1.
A pressure of 10−6 Torr or lower is a typical operating pressure of a linear quadrupole or time of flight mass analyzer and the critical length scale is on the order of 100 mm. Such values lead to Kn numbers of several hundred. A typical operational pressure of an ion trap mass spectrometer with a ring electrode radius of 10 mm is 10−4 Torr, leading to Kn numbers of about 100. The operating regime of primary interest in this application is at pressures greater than 50 mTorr and critical length scales, z0 values, or, for certain trap configurations, r0 values, of less than 1 mm. In all of these cases listed in Table 1, Kn is less than 10 and all but one example is less than unity.
Embodiments of the present invention perform mass spectrometry under unconventional conditions where Kn has values near unity and below (less than 10 and less than 1, for example). At such pressures and fundamental length scales, the mean free path is similar to, or less than, the critical experimental length scale. Embodiments of the invention maybe particularly suitable for Paul trap mass analyzers, commonly referred to as ion trap mass analyzers, that have fundamental length scales that are less than 1 mm, e.g., the radius of the ring electrode, r0, is 1 mm or less. Embodiments of the invention are directed to high-pressure mass spectrometers that can be operated at pressures of about 50 mTorr and above or about 100 mTorr and above (e.g., to 1 Torr,10 Torr, 100 Torr or 1000 Torr, for example) and/or with Kn values about less than 10, about one, or even less than one.
The term “high resolution” refers to mass spectra that can be reliably resolved to less than 1 Th, e.g., having a line width less than 1 Th (FWHM). “Th” is a Thompson unit of mass to charge ratio. The high resolution operation may allow the use of monoisotopic mass to identify the substance under analysis.
The term “high detector sensitivity” refers to detectors that can detect signals on a low end ranging from 1-100 charges per second.
The term “high pressure” refers to an operational background pressure in a chamber or sub-chamber holding a mass analyzer being between about 10 mTorr to about 100 Torr, typically between about 50 mTorr to about 10 Torr, and more typically between about 100 mTorr and about 10 Torr.
As shown in
In some embodiments, one of the endcap electrodes 31, 32 can be sealably attached to the ring electrode 33 with a gas impermeable electrically insulating sealant 30m (
As shown in
Typical sample S inlet flow rates into one or more inlets I are about 1 sccm but may be greater or smaller.
The two adjacent chambers/compartments 20A, 20B can be held by a compact, light weight housing 20h that may have a unitary body or may be provided as a plurality of attached housing bodies.
The differential operational pressures P1, P2 can be selected to provide convective gas flow through the ring electrode 33 and ejector endcap 32 of the mass analyzer 30 toward the detector 40 for signal enhancement at the detector 40. The operational pressures P1, P2 and pressure ratios P2/P1 can vary or be dependent on whether a buffer gas is used and/or the type of buffer gas used as well as critical dimensions of components the mass spectrometer, for example, a critical dimension of some configurations of a microscale ion trap, r0 and/or z0. Evaluation of whether signal enhancement is provided by convective gas flow for a respective mass spectrometer 10 can be carried out by comparing operation with and without the differential pressure.
For purposes of evaluating infringement, the signal enhancement of respective MS devices can be evaluated using a known suitable control sample such as mesitylene and the P1=P2 operation versus a P2/P1 <1 operation. Thus, whether there is analyte signal enhancement can be evaluated by comparing a baseline peak signal at P1=P2 with a corresponding peak signal at P2/P1<1 (or other claimed range where P2 is <P1), to determine if there is signal (peak) enhancement of an ion associated with a test sample of mesitylene in a mass spectrometer with an ion trap. The at least one detected ion signal associated with the ion of the test sample is not limited to just the molecular ion but any ions related to the test sample.
For example, as shown in
Unexpectedly, signal improvement/enhancement using a relatively small pressure differential can provide enhanced signal for improved detection limits Increasing pressure differentials does not significantly enhance signal (
It is noted that embodiments of the invention are directed to compact configurations of ion trap mass analyzers for a device that determines ion mass to charge ratio and can additionally provide relative abundance information for a number of ions ranging across mass to charge values. The specific examples described herein are particularly relevant to ion trap mass analyzers such as the Paul trap, cylindrical ion trap (CIT), Stretched Length Ion Trap (SLIT), and the rectilinear ion trap, for example.
In the embodiment shown in
In some embodiments, the ion trap 30 can have a stretched length ion trap (SLIT) configuration. See, e.g., U.S. Pat. No. 8,878,127, to Ramsey et al., entitled “Miniature Charged Particle Trap With Elongated Trapping Region For Mass Spectrometry”, the contents of which are hereby incorporated by reference as if recited in full herein. However, other ion trap aperture shapes and aperture array configurations may be used.
Referring to
The pressures P1 and P2 can be controlled so as to be substantially constant with a substantially fixed pressure ratio between chambers/compartments 20A and 20B and/or at least between the ring electrode of the mass analyzer and the detector interface. The mass spectrometer can run (flow gas through and perform mass resonance scans) continuously for at least a defined time period such as 8 hours, 12 hours, 24 hours, or over other time periods such as days, weeks, months and the like.
Pressure P1 and/or P2 may vary somewhat over time (e.g., 10-20%) without unduly affecting performance, but are typically held constant, on average over time of a suitable operational period, typically of at least 8 hours.
In some embodiments, each chamber or chamber segment 20A, 20B can include at least one valve 80v, 85v in communication to a respective vacuum pump, 80, 85, respectively, that can be used to control the pressure P1, P2 in the respective chambers, or sub-chambers.
As shown in
The sealant 30m forming the sealed space 30s can comprise one or more of a electrically insulating, gas impermeable plug, washer, gasket, RF putty, or other suitable material. The sealant 30m may be used with insulating spacers or layers 201 (
The mass spectrometer 10 can be configured to operate with substantially continuous convective gas flow through the mass analyzer over a suitable operational period of days, weeks or months, for example.
The spectrometer 10 can include a buffer gas source B (
A vacuum feed-through 99 can reside on one end of the chamber 20B, but can be located in other regions. In some optional embodiments, an SMA connector can be used as a plug and extension chamber to hold pressure in the chamber 20B.
A valve 85v (
As shown in
Still referring to
In some embodiments, the volume in the first compartment/chamber 20A is greater than that of the second compartment/chamber 20B by between about 10-40%. In other embodiments the volume in the first compartment/chamber 20A is less than that of the second compartment/chamber 20B by between about 10-40%. In some particular embodiments, each volume of the chamber or compartment 20A, 20B can be relatively small, such as between about 0.25 in3 to about 16 in3, typically between about 1 in3 to about 10 in3, such as about 1 in3, about 2 in3, about 3 in3, about 4 in3, about 5 in3, about 6 in3, about 7 in3, about 8 in3, about 9 in3, about 10 in3.
As shown in
In some embodiments, the forward end of the ion trap 30 is closely spaced to be in close spatial proximity of the detector 40, which may be particularly advantageous for small mass spectrometry systems operating at high pressure (e.g., in some examples, approximately>1 Torr) due to the reduced mean free paths experienced by the ejected ions at such pressures. In some embodiments, the spacing D (
As noted above, the ion trap 30 can be held by a mounting fixture 140. The subassembly 30s is typically oriented with the mounting fixture 140 sealably engaging a wall or ledge 20l in the housing 20h to form the wall or partition 20w as shown in
The ion trap endcap electrodes 31, 32, and ring electrode 33 can be sealably attached to each other to generate convective buffer gas flow with the gas transport to be primarily or substantially only through the ring electrode and ejector endcap. In some embodiments, the ion trap 30 can be mounted directly to the internal wall 20w without requiring a separate mounting fixture 140.
In some embodiments, the mass spectrometer system 100 can be configured with one or more ion traps 30 and/or the ion traps 30 can comprise more than one trapping cavity. In some embodiments, mass ejection from each of the cavities may be detected by a single detector 40 to produce a composite (combined enhanced) mass spectrometry signal. In some embodiments, the signal for detection may be based on outputs from a subset of different traps. In some embodiments, mass ejection from each or a subset or groups of cavities may be detected by separate detectors. This arrangement may be useful in cases where each cavity or groups (subsets) of cavities have different trapping properties. For example, an arrangement of this type may extend the range of ion masses that can be analyzed by the spectrometer system.
In some embodiments, a portable, light weight mass spectrometer 10 can be configured to have a plurality of the dual chamber devices 20h so as to concurrently sample multiple samples using a common or different detector or detectors
In some embodiments, the mass spectrometer 10 comprises a microscale ion trap 30 configured to have a pressure P2 that is between about 90% to about 10% of P1.
In some embodiments, which may be particularly suitable for microscale ion traps, P2/P1 is less than 1, typically between 0.95 and 0.1, more typically between 0.9 and 0.5.
In some embodiments, for example, where P1 is about 1.77 Torr, P2 can be between about 1.70 Torr and about 17 mTorr, typically about 1.70 Torr and 0.5 Torr. In some embodiments, when P1 is about 1 Torr, P2 can be between about 10 mTorr to about 950 mTorr, typically between about 500 mTorr and 900 mTorr.
In some embodiments, P2/P1 is between about 0.9 to about 0.5, such as 0.9, 0. 85, 0.8, 0.75, 0.70, 0.65, 0.60, 0.65, 0.60, 0.55 and 0.50 and any value therebetween. Thus, where P1 is about 1 Torr, P2 is about 500 mTorr. Lower P2 pressures may be used relative to P1, but it has been found that further decreases of pressure P2 on the detector side does not increase peak signal intensity (m/z (Th)), at least for some buffer gases.
The apertures 31a, 32a, 33a each have a radius r0 or average effective radius (e.g., the latter calculates an average hole size using shape and width/height dimensions where non-circular aperture shapes are used) and the trap 34 has a corresponding diameter or average cross distance 2r0 and an effective length 2z0. The ion trap 34 can be configured to have a defined ratio of z0/r0 that is greater than 0.83. Note that z0 can be defined as the half-height of the cavity, half height of the aperture 33a plus the distance from the aperture 33a to the end cap electrode 32. In some embodiments, the ion trap aperture array has an effective length 2z0measured as the distance between interior surfaces of the end caps 31, 32. The array can be configured to have a defined ratio of z0/r0 that is near unity but is generally greater than unity by a few tens of percent (e.g., 110%-130%). The r0 and z0 dimensions can be between about 0.5 μm to about 1 cm, but for microscale mass spectrometry applications contemplated by certain embodiments of the invention, these dimensions are preferably 1 mm or less, down to about 0.5 μm.
The spacing between electrodes 31, 32, 33 can be set with planar insulators 202 shown by way of example in
Referring to
As shown in
The electrodes 31, 32, 33 can have a plurality of, typically three, circumferentially spaced apart ears 31e. Nylon screws 144 can be used to attach the components of the ion trap 30. However, it is also contemplated that the electrode and insulator components can be bonded or otherwise integrated into a unit.
Solder tabs 31t, 32t protruding from the electrodes 31, 32 (and 33) can provide convenient electrical connections to the ion trap 30. Pin connectors 146 can be attached (e.g., adhesively attached, soldered or brazed) to the electrode tabs 31e for easy trap modification or removal. A plurality of circumferentially spaced apart alignment apertures 149 on each of the electrodes 31, 32, 33 can accept alignment pins. The alignment apertures can be small, typically between about 0.1-2 mm, e g., about a 1 mm diameter hole. The alignment apertures 149 can be used for accurate alignment of the electrodes 31, 32, 33 using correspondingly sized pins, e.g., for 1 mm apertures, about 1 mm diameter pins.
In some embodiments, a plurality (e.g., 3-6), shown as three, circumferentially spaced apart neighboring holes can have concentric features of decreasing diameter size for allowing measurement of electrode alignment, typically under a microscope. This allows for rapid verification of trap alignment prior to installation in the spectrometer housing. The end cap hole 32a of the single ion trap (CIT) 34 is visible in the center of the top electrode 32 in
In some embodiments, the ionization source 50, a mass analyzer 30 (such as, but not limited to, an ion trap mass analyzer), and the detector 40 can all be arranged as a releasably attached set or integrally attached unit of stacked planar conductor and insulator components, e.g., typically alternating conductive and insulating films, substrates, sheets, plates and/or layers or combinations thereof, with defined features for the desired function. See, e.g., co-pending, co-assigned U.S. patent application Ser. No. 13/804,911, the contents of which are hereby incorporated by reference as if recited in full herein.
The ionizer can be any suitable ionizer as is known to those of skill in the art. Array ionizers may also be used. Examples of types of ionization that can be provided in array form include, but are not limited to, cold field electron emitters, miniature gas plasma sources, and field ionization. Applying an appropriate magnitude electrical potential between the two conducting electrodes 31, 32 can generate electric field strengths to affect cold field emission of electrons, formation of a gas plasma, or field ionization of molecules or atoms. The close spatial proximity of the ionization array of the ion trap 30, may be particularly advantageous for small mass spectrometry systems operating at high pressure (approximately >1 Torr) due to the reduced mean free paths experienced by the ions or electrons at such pressures.
It is well known that ion traps 30 generate mass spectral information by ejecting an ensemble of trapped ions in an orderly fashion such that ions of a given mass to charge range are ejected through the end cap holes 32a during a defined or selected time period. Thus, the detector 40 comprises an appropriate transducer. The transducer typically comprises an electron multiplier but may be a planar detector 40 and, in particular embodiments, as shown in
Charge detection provided by a planar detector 40 may be particularly attractive for small mass spectrometry systems due to their inherently small size and weight and the ability to operate at pressures from low vacuum to atmospheric pressure. Charges collected by a conductive film or other conductor associated with the detector 40 can be measured either with an electrometer or a charge sensitive transimpedance amplifier. The term “electronic collector” refers to an electronic circuit that can detect charges collected by the film and/or conductor.
For example, the detector 40 can be configured to detect ions ejected in parallel from a planar CIT array with a planar electrode with a solid continuous conductive surface over the holes of the end cap electrode 32a. The gain of a charge sensitive transimpedance amplifier 92 (
In some embodiments, the housing 100h can releasably attach a canister of pressurized buffer gas “B” that connects to a flow path into the (vacuum) chamber 20A. The housing 100h can hold a control circuit 100c and various power supplies 84, 86 that connect to components/conductors to carry out the ionization, mass analysis and detection. The housing 100h can hold one or more amplifiers including an output amplifier 92 that connects to a processor 100p for generating the mass spectra output.
The portable and/or compact system 100 can be lightweight, typically between about 1-15 pounds (including a vacuum pump or pumps), where used. The housing 100h can be configured as a handheld housing (
The system 100 may also include a transceiver, GPS module and antenna and can be configured to communicate with a smartphone or other pervasive computing device (laptop, electronic notebook, PDA, IPAD, and the like) to transfer data or for control of operation, e.g., with a secure APP or other wireless programmable communication protocol.
The system 100 can be configured to operate at pressures at or greater than about 100 mTorr up to atmospheric.
In some embodiments, the mass spectrometer 100 is configured so that the ion source (ionizer) 50, mass analyzer 30 and detector 40 operate at near isobaric conditions and at a pressure that is greater than 100 mTorr. The term “near isobaric conditions” includes those in which the pressure between any two adjacent chambers differs by no more than a factor of 100, but typically no more than a factor of 10. In some embodiments, the background pressures P1, P2 in respective chambers 20A and 20B define the pressure ratio P2/P1 to be 0.1<P2/P1<1.
As shown in
As shown in
Generally stated, electrons are generated in a well-known manner by source 50 and are directed towards the mass analyzer (e.g., ion trap) 30 by an accelerating potential. Electrons ionize sample gas S in the mass analyzer 30. For ion trap configurations, RF trapping and ejecting circuitry is coupled to the mass analyzer 30 to create alternating electric fields within ion trap 30 to first trap and then eject ions in a manner proportional to the mass to charge ratio of the ions. The ion trap 30 with the spectrometer housing 20h generating differential pressure can generate the convective buffer gas flow through the ring electrode and ejector endcap in the viscous or transitional flow regime to the detector side of the chamber or sub-chamber 20B.
The ion detector 40 registers the number of ions emitted at different time intervals that correspond to particular ion masses to perform mass spectrometric chemical analysis. The ion trap dynamically traps ions from a measurement sample using a dynamic electric field generated by an RF drive signal 75s. The ions are selectively ejected corresponding to their mass-to-charge ratio (mass (m)/charge (z)) by changing the characteristics (amplitude, frequency, etc.) of the trapping radio frequency (RF) electric field.
Relative ion abundances (e.g., ion numbers) at particular m/z ratios can be digitized for analysis and can be displayed as spectra on an onboard and/or remote processor 100p. The signal can be enhanced using the convective buffer gas flow and/or differential pressure at the Kn number range noted above.
In the simplest form, a signal of constant RF frequency can be applied to the center electrode 33 relative to the two end cap electrodes 31, 32. The amplitude of the center electrode signal can be ramped up linearly in order to selectively destabilize different m/z of ions held within the ion trap. This amplitude ejection configuration may not result in optimal performance or resolution. However, this amplitude ejection method may be improved upon by applying a second signal differentially across the end caps 31, 32. This axial RF signal, where used, causes a dipole axial excitation that can result in the resonant ejection of ions from the ion trap when the ions' secular frequency of oscillation within the trap matches the end cap excitation frequency.
The ion trap 30 or mass filter can have an equivalent circuit that appears as a nearly pure capacitance. The amplitude of the voltage to drive the ion trap 30 may be high (e.g., 100 V-1500 Volts) and can employ a transformer coupling to generate the high voltage. The inductance of the transformer secondary and the capacitance of the ion trap can form a parallel tank circuit. Driving this circuit at resonant frequency may be desired to avoid unnecessary losses and/or an increase in circuit size.
Sample S may be introduced into the chamber 20A with a buffer gas B through an input port I toward the ion trap 30. The S intake from the environment into the housing 100h can be at any suitable location (shown by way of example only from the bottom). One or more sample intake ports can be used.
The buffer gas B can be provided as a pressurized canister 110 of buffer gas as the source. However, any suitable buffer gas or buffer gas mixture including air, helium, hydrogen, or other gas can be used. Where air is used, it can be pulled from atmosphere and no pressurized canister or other source is required. Typically, the buffer gas comprises helium, typically above about 90% helium in suitable purity (e.g., 99% or above) or suitably pure nitrogen. A mass flow controller (MFC) 122 (
The portable mass spectrometer can be a hand-held device that weighs between 1-10 pounds with onboard vacuum pumps (block 266).
The mass analyzer can be a microscale ion trap (block 276).
The detector can be aligned with and closely spaced to an end cap of the mass analyzer (block 277).
The first chamber can be held at a background pressure P1 of between about 1-2 Torr (block 278).
The second chamber can be held at a background pressure P2, where P2/P1 is less than 1 and about 0.1 or above (block 279). The pressure ratio P2/P1 can be one of 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0.30, 0.25, 0.20, 0.15, and about 0.10.
One or more mass spectrometers 10, which may be high-resolution and/or high-sensitivity units, may be placed in or at a hazard site to analyze gases and remotely send back a report of conditions presenting danger to personnel. A mass spectrometer 10 may be placed at strategic positions on air or land transport to test the environment for hazardous gases that may be an indication of malfunction or even a terrorist threat. Embodiments of the present invention provide portable mass spectrometers suitable for handheld, field use.
Embodiments of the present invention may take the form of software and hardware aspects, all generally referred to herein as a “circuit” or “module.”
As will be appreciated by one of skill in the art, features or embodiments of the present invention may be embodied as an apparatus, a method, data or signal processing system, or computer program product. Furthermore, certain embodiments of the present invention may include an Application Specific Integrated Circuit (ASIC) and/or computer program product on a computer-usable storage medium having computer-usable program code means embodied in the medium. Any suitable computer readable medium may be utilized including hard disks, CD-ROMs, optical storage devices, or magnetic storage devices. A processor can include one or more digital microprocessors.
The computer-usable or computer-readable medium may be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CD-ROM). Note that the computer-usable or computer-readable medium could even be paper or another suitable medium, upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
Computer program code for carrying out operations of the present invention may be written in an object oriented programming language such as Java7, Smalltalk, Python, Labview, C++, or VisualBasic. However, the computer program code for carrying out operations of the present invention may also be written in conventional procedural programming languages, such as the “C” programming language or even assembly language. The program code may execute entirely on the spectrometer computer and/or processor, partly on the spectrometer computer and/or processor, as a stand-alone software package, partly on the spectrometer computer and/or processor and partly on a remote computer, processor or server or entirely on the remote computer, processor and/or server. In the latter scenario, the remote computer, processor and/or server may be connected to the spectrometer computer and/or processor through a LAN or a WAN, or the connection may be made to an external computer, processor and/or server (for example, through the Internet using an Internet Service Provider).
The flowcharts and block diagrams of certain of the figures herein illustrate the architecture, functionality, and operation of possible implementations of mass spectrometers or assemblies thereof and/or programs according to the present invention. In this regard, each block in the flow charts or block diagrams represents a module, segment, operation, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks might occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.
The mass spectrometer 10 can include a circuit 100c with an onboard display 90 and/or one or more on-board processors 100p that direct the operation of the different component control signals. As shown in
The mass spectrometer 10 can include or communicate with an analysis module and/or circuit that can identify a substance by the obtained mass spectral information. The analysis module or circuit can be onboard or at least partially remote from the spectrometer device 10. If the latter, the analysis module or circuit can reside totally or partially on a server. The server can be provided using cloud computing which includes the provision of computational resources on demand via a computer network. The resources can be embodied as various infrastructure services (e.g. computer, storage, etc.) as well as applications, databases, file services, email, etc. In the traditional model of computing, both data and software are typically fully contained on the user's computer; in cloud computing, the user's computer may contain little software or data (perhaps an operating system and/or web browser), and may serve as little more than a display terminal for processes occurring on a network of external computers. A cloud computing service (or an aggregation of multiple cloud resources) may be generally referred to as the “Cloud”. Cloud storage may include a model of networked computer data storage where data is stored on multiple virtual servers, rather than being hosted on one or more dedicated servers. Data transfer can be encrypted and can be done via the Internet using any appropriate firewalls, as suitable for the data collected.
As shown in
The data 356 may include pressure data, which may be obtained from sensors 66 (
The I/O device drivers 358 typically include software routines accessed through the operating system 352 by the application programs 354 to communicate with devices such as I/O data port(s), data storage 356 and certain memory 314 components and/or the image acquisition system 320. The application programs 354 are illustrative of the programs that implement the various features of the data processing system 305 and can include at least one application, which supports operations according to embodiments of the present invention. Finally, the data 356 represents the static and dynamic data used by the application programs 354, the operating system 352, the I/O device drivers 358, and other software programs that may reside in the memory 314.
While the present invention is illustrated, for example, with reference to the Module 350 being an application program in
As shown in
Embodiments of the invention will be described further with respect to the non-limiting examples provided below.
Introduction
Miniature cylindrical ion traps (CIT) at pressures of ≈1 Torr were chosen for reduction to practice examples of some embodiments of the present invention. Significant reduction in size, weight, and, power (SWaP) results from the diminished pumping requirements of high-pressure operation. Standard electron multiplier detectors cannot be utilized at high pressures. Dual differentially pumped chambers were used to simultaneously achieve reduced pumping requirements and high detector sensitivity. In these configurations, the ionizer/trap and detector are held at two different pressures. One result of differential pumping is gas flow through the CIT mounted on the partition between the chambers. Simulations and experimental studies of the impact of buffer gas flow on mass spectral performance are discussed below.
Experimental setup
During the experiment, the trap chamber was held at a constant pressure P1 adjusted by a needle valve. A 10 liter Tedlar bag was connected to the Inlet filled with either N2 or He and approximately 20 ppm mesitylene. Most of the gas load was by-passed to a roughing pump before entering the trap chamber.
The detector chamber was directly mounted to the entrance of a 801/s turbo pump through a shut off valve. The pressure in the detector chamber (P2) could be controlled by reducing the conductance of the valve from fully open to fully closed position. Pressures were measured by a 275i KJLC convectron gauge (P1) and an Agilent FRG-700 gauge (P2).
Both gauges were calibrated to a 0.2% accuracy against an Inficon Capacitance Manometer (part number CDG025D) and pressure measurements were corrected. A 7-CIT array (traps dimensions r0=0.5 mm, Ring thickness=0.79 mm, electrodes spacing=0.250 mm, End cap holes radius=0.200 mm) was used to maximize the signal intensity. A 7.11 MHz drive RF voltage was applied between the ring electrode and the end caps ramped from 184 V0-p, (trapping voltage) to 406 V0-p.
Results in Nitrogen (
Results in Helium (
A higher pressure of 1.77 Torr, required to ignite the plasma of the GD, was maintained on the trap side (the Pashen curve in He being shifted to higher P×dist. region with respect to N2). Similar to the experiments using nitrogen buffer gas, the ion signal increases as the pressure ratio of P2/P1 is changed from unity to lesser values. The signal maximizes for relatively small differences in pressure as with nitrogen.
Gas Throughput (
(ref. A. Chambers, 2005, Modern Vacuum Physics, Chapman and Hall/CRC, Boca Rotan, USA, the contents of which are hereby incorporated by reference as if recited in full herein). However, some simulations of flow with P1 at about 1 Torr (transition flow regime) have shown characteristic choked flow at lower ratios (P2/P1 of about 0.1 or even 0.05) with pressure differentials 1 Torr (P1) to 0.1 Torr (P2) and Equation 2 may not accurately reflect these critical pressure ratios.
Once choked flow conditions are reached across the exit endcap aperture, any further decrease of the downstream pressure cannot be communicated upstream. Thus, no change in mass flow rate through the trap or pressure within the trap will occur if the downstream pressure is decreased below the critical pressure and the ion signal will not further increase.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.
This application is a divisional application of U.S. application Ser. No. 14/734,623, filed Jun. 9, 2015, which claims the benefit of and priority to U.S. Provisional Application Ser. No. 62/010,050, filed Jun. 10, 2014, the contents of which are hereby incorporated by reference as if recited in full herein.
This invention was made with government support under grant number W911NF-12-1-0539 awarded by the U.S. Army Research Office. The United States government has certain rights in the invention.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2939952 | Paul et al. | Jun 1960 | A |
| 5051582 | Bahns et al. | Sep 1991 | A |
| 5115131 | Jorgenson | May 1992 | A |
| 5118950 | Bahns et al. | Jun 1992 | A |
| 5206506 | Kirchner | Apr 1993 | A |
| 5248883 | Brewer et al. | Sep 1993 | A |
| 5596193 | Chutjian et al. | Jan 1997 | A |
| 5613294 | Ferran | Mar 1997 | A |
| 5793091 | Devoe | Aug 1998 | A |
| 5811820 | Kirchner et al. | Sep 1998 | A |
| 5859433 | Franzen | Jan 1999 | A |
| 5866901 | Penn et al. | Feb 1999 | A |
| 6157031 | Prestage | Dec 2000 | A |
| 6452326 | Ge et al. | Sep 2002 | B1 |
| 6469298 | Ramsey | Oct 2002 | B1 |
| 6483109 | Reinhold et al. | Nov 2002 | B1 |
| 6521898 | Chutjian et al. | Feb 2003 | B2 |
| 6545268 | Verenthchikov et al. | Apr 2003 | B1 |
| 6762406 | Cooks et al. | Jul 2004 | B2 |
| 6822225 | Xu et al. | Nov 2004 | B2 |
| 6838666 | Ouyang et al. | Jan 2005 | B2 |
| 6870158 | Blain | Mar 2005 | B1 |
| 6933498 | Whitten et al. | Aug 2005 | B1 |
| 7560688 | Clowers et al. | Jul 2009 | B2 |
| 7772546 | Jackson | Aug 2010 | B2 |
| 7973277 | Rafferty | Jul 2011 | B2 |
| 8101908 | Senko | Jan 2012 | B2 |
| 8878127 | Ramsey et al. | Nov 2014 | B2 |
| 9406492 | Ramsey | Aug 2016 | B1 |
| 20020195559 | Miseki | Dec 2002 | A1 |
| 20030066958 | Okumura | Apr 2003 | A1 |
| 20040079874 | Bateman | Apr 2004 | A1 |
| 20040089799 | Kawato | May 2004 | A1 |
| 20040135080 | Ouyang et al. | Jul 2004 | A1 |
| 20040164240 | Okumura | Aug 2004 | A1 |
| 20050061966 | Ding | Mar 2005 | A1 |
| 20050196720 | Ostler et al. | Sep 2005 | A1 |
| 20060219888 | Jachowski et al. | Oct 2006 | A1 |
| 20070045533 | Krutchinsky | Mar 2007 | A1 |
| 20070158543 | Glowers et al. | Jul 2007 | A1 |
| 20090294655 | Ding et al. | Dec 2009 | A1 |
| 20100084549 | Ermakov et al. | Apr 2010 | A1 |
| 20110147581 | Chen et al. | Jun 2011 | A1 |
| 20110248160 | Belov | Oct 2011 | A1 |
| 20120138790 | Wright | Jun 2012 | A1 |
| 20120256083 | Kovtoun | Oct 2012 | A1 |
| 20120267523 | Lammert | Oct 2012 | A1 |
| 20130015347 | Steiner | Jan 2013 | A1 |
| 20130043382 | Berkout | Feb 2013 | A1 |
| 20130240724 | Guna | Sep 2013 | A1 |
| 20140183355 | Bartfay-Szabo | Jul 2014 | A1 |
| 20140209814 | Whitehouse | Jul 2014 | A1 |
| 20140263999 | Ramsey et al. | Sep 2014 | A1 |
| 20140264013 | Rafferty | Sep 2014 | A1 |
| 20150008320 | Loboda | Jan 2015 | A1 |
| 20150034820 | Evans-Nguyen | Feb 2015 | A1 |
| 20160042936 | Brown | Feb 2016 | A1 |
| 20160093479 | Gordon | Mar 2016 | A1 |
| 20160118238 | Gordon | Apr 2016 | A1 |
| 20170084439 | Brown | Mar 2017 | A1 |
| Entry |
|---|
| Alberici et al., “Ambient mass spectrometry: bringing MS into the ‘real world’”, Anal. Bioanal. Chem. 398: 265-294 (2010). |
| Albrieux et al. “Ion trajectory simulations in a high-pressure cylindrical ion trap”, European J. Mas Spectrum. 16:357-565 (2010). |
| Allied Electronics, GC Electronics 10-8880 Product Detail, Chemical, High Voltage Putty, Printed from the internet: Jun. 10, 2014. |
| Amini et at. “Microfabricated Chip Traps for Ions”, Atom Chips (2011). |
| Austin et al. Halo Ion Trap Mass Spectrometer, Anal. Chem. 79, 2927-2932 (2007). |
| Austin et al. “Simulations of Ion Trapping in a Micrometer-Sized Cylindrical Ion Trap”, J.Am. Soc. Mass Spectrom. 17:30-441 (2006). |
| Badman et al. “A Miniature Cylindrical Quadrupole Ion Trap: Simulation and Experiment”, Anal. Cham. 70: 4896-4901 (1998). |
| Badman et al. “A Parallel Miniature Cylindrical Ion Trap Array” Anal. Chem. 72, 3291-3297 (2000). |
| Badman et al. “Miniature mass analyzers” J. Mass Spectrum. 35: 659-671 (2000). |
| Blain et al. “Micro Mass Spectrometer on a Chip” Sandia Report SAND2005-6838 (2005). |
| Blain, “Towards the Hand-held Mass Spectrometer: Design Considerations, Simulation, and Fabrication of Micrometer-Scaled Cylindrical Ion Traps”, International Journal of Mass Spectrometry, (2004). |
| Bonner et al. “The Cylindrical Ion Trap. Part 1. General Introduction” International Journal of Mass Spectrometry and Ion Physics, (1977). |
| Brewer et al. “Planar ion microtraps”, Phys. Rev. A 46(11): R6781-R6784 (1992). |
| Chaudhary et al. “Fabrication and Testing of a Miniature Cylindrical Ion Trap Mass Spectrometer Constructed from Low Temperature Co-fired Ceramics” www.elesevier.com/locate/ijms (2006). |
| Chen et al. “A Micro Ionizer for Portable Mass Spectromerters using Double-gated Isolated Vertically Aligned Carbon Nanofiber Arrays” IEEE Trans. Electron Devices, 58(7): 2149-2158 (2011). |
| Cheung, Kerry, “Chip-Scale Quadrupole Mass Filters for a Micro-Gas Analyzer”, Ph.D. Thesis, Massachusetts Institute of Technology, Jun. 2009. |
| Contreras et al. “Hand-Portable Gas Chromatograph- Toroidal Ion Trap Mass Spectrometer (GC-TMS) for Detection of Hazardous Compounds”, J Am Soc Mass Spectrom (2008). |
| Coupier B. et al. “Development of a miniature ion trap mass spectrometer for applications requiring portability”, Presented at 60th ASMS Conference on Mass Spectrometry and Allied Topics, Vancouver, Canada, May 24, 2012. |
| Coupier B. et al. “Study of the Impact of Gas Flow in a Microscale Ion Trap Operated at High Pressure” Presented at 62nd ASMS Conference on Mass Spectrometry and Allied Topics, Baltimore, Maryland, Jun. 17, 2014. |
| Cruz et al. “Design, microfabrication, and analysis of micrometer-sized cylindrical ion trap arrays” Rev. Sci. Instrum. 78: 015107 (2007). |
| Falconer et al. “High Pressure Ion Detection for Miniaturized Mass Spectrometers”, Presentation at 58th ASMS Conference 2010, Salt Lake City, UT, May 23, 2010. |
| Ferran et al. “High-pressure effects in miniature arrays of quadrupole analyzers for residual gas analysis from 10-9 to 10-2 Torr”, J. Vac. Sci. Technol. A 14(3) 1258-1265 (1996). |
| Fico et al. “Circular Arrays of Polymer-Based Miniature Rectilinear Ion Traps”, www.rsc.org/analyst, 2009. |
| Gao et al. “Design and Characterization of a Multisource Hand-Held Tandem Mass Spectrometer”, Anal. Chem 80(19): 7198-7205 (2008). |
| Gao et at. “Handheld Rectilinear Ion Trap Mass Spectrometer” Anal. Chem. 78:5994-6002 (2006). |
| Gao, Liang “Miniaturization of the Ion Trap Mass Spectrometer”, Ph.D. Thesis, Purdue University, 2009. |
| Goeringer et al. “Theory of High-Resoluction Mass Spectrometry Achieved via Resonance Ejection in the Quadrupole Ion Trap”, Anal. Chem. 64: 1434-1439 (1992). |
| Hadjar et al. “High-efficiency cross-beam magnetic electron-impact source for improved miniature Mattauch-Herzog mass spectrometer performance”, Rev. Sci. Instrum. 83: 064101 (2012). |
| Hager “A New Linear Ion Trap Mass Spectrometer”, Rapid Commun. Mass Spectrom. 2002. |
| Harris et al. “Ambient Sampling/Ionization. Mass Spectrometry: Applications and Current Trends” Anal. Chem. 83: 4508-4538 (2011). |
| Harris et al. “Transportable real-time single-particle ion trap mass spectrometer”, Rev. Sci Instrum. 76:064102 (2005). |
| Hensinger et al. “T-juction ion trap array for two-dimensional ion shuttling, storage, and manipulation”, Applied Physics Letters, 88, 034101 (2006). |
| Hood, Derrell L. “Development of a Novel Loeb-Eiber Mass Filter”, M.S. Thesis, Ohio State University 2009. |
| Huang et al. “Direct analysis of melamine in complex matrices using a handheld mass spectrometer” Analyst 135: 705-711 (2010). |
| Keil et al. “Ambient Mass Spectrometry with a Handheld Mass Spectrometer at High Pressure”, Anal. Chem. 79:7734-7739 (2007). |
| Knapman et al. “Considerations in experimental and theoretical collision cross-section measurements of small molecules using travelling wave ion mobility spectrometry-mass spectrometry”, Intl. J. Mass Spectrom, 2010, 298, 17-23. |
| Knight, “The Development of a Micro-Faraday Array for Ion Detection”, www.elsevier.com/locate/ijms (2002). |
| Kornienko et al. “Electron impact ionization in a microion trap mass spectrometer”, Ref. Sci. Instrum. 70(10): 3907-3909 (1999). |
| Kornienko et al. “Micro Ion Trap Mass Spectrometry”, Rapid Commun. Mass Spectrom. 13:50-53 (1999). |
| Kornienko, “Field-Emission Cold-Cathode El Source for a Microscale Ion Trap Mass Spectrometer”, Anal. Chem. 2000, 72, 559-562. |
| Lammert et al. “Miniature Toroidal Radio Frequency Ion Trap Mass Analyzer”, J Am Soc Mass Spectrum 2006. |
| Lammert, “Design, Optimization and Initial Performance of a Toroidal RF Ion Trap Mass Spectrometer”, Int. Journal of Mass Spectrometry, 2001. |
| Lammert, et al. “Experimental Investigation into the Performance of Ion Traps Using Air Versus Helium as the Buffer Gas”, Rapid Communication in Mass Spectrometry, 1996. |
| Li et al. “Ion Trap Array Mass Analyzer: Structure and Performance”, Anal. Chem. 81:4840-4846 (2009). |
| March, Raymond E. “An Introduction to Quadrupole Ion Trap Mass Spectrometry”, J. Mass Spectrom. 32:351-369 (1997). |
| March, Raymond E. “Quadrupole Ion Trap Mass Spectrometer”, Encyclopedia of Analytical Chemistry, pp. 11848-11872 (2000). |
| Mass et al. “Miniature Monolithic Rectilinear Ion Trap Arrays by Stereolithiography on Printed Circuit Board”, Journal of Microelectromechanical Systems, 2010. |
| Mass et al. RF Planar Ion Trap for Chemical Sensing: Electrical Engineering Dept., Purdue University, 2011. |
| Misharin et al. “Development and characterization of a field deployable ion trap mass spectrometer with atmospheric pressure interface” Anal. Chem. 84(22): 10105-10112 (2012). |
| Moxom et al. “Analysis of Volatile Organic Compounds in Air with a Micro Ion Trap Mass Analyzer”, Anal. Chem. 75:3739-3743 (2003). |
| Moxom et al. “Double resonance ejection in a micro ion trap mass spectrometer” Rapid Commun. Mass Spectrom. 16:755-760 (2002). |
| Moxom et al. “Sample pressure effects in a micro ion trap mass spectrometer” Rapid Commun. Mass Spectrom. 18: 721-723 (2004). |
| Orient et al. “Miniature, high-resolution, quadrupole mass-spectrometer array”, Rev. Sci. Instrum. 68: 1393-1397 (1997). |
| Ouyang et al. “Handheld Miniature Ion Trap Mass Spectrometers” Analytical Chemistry, 2009. |
| Ouyang et al. “Quadrupole Ion Traps and Trap Arrays: Geometry, Material, Scale, Performance” Eur. J. Mass Spectrom, 2007. |
| Ouyang et al. “Rectilinear Ion Trap: Concepts, Calculations, and Analytical Performance of a New Mass Analyzer” Anal. Chem. 76: 4595-4605 (2004). |
| Patterson et al. “Miniature Cylindrical Ion Trap Mass Spectrometer”, Anal. Chem. Purdue University, 2002. |
| Pau et al. “Microfabricated Quadrupole Ion Trap for Mass Spectrometer Applications”, Phys. Rev. Lett. 96: 120801 (2006). |
| Pau et al. “Planar Geometry for Trapping and Separating Ions and Charged Particles” Anal. Chem. 79:6857-6861, 2007. |
| Peng et al. “Coaxial Ion Trap Mass Spectrometer: Concentric Toroidal and Quadrupolar Trapping Regions” Analytical Chemistry, 2011. |
| Peng et al. “New Approaches to Miniaturizing Ion Trap Mass Analyzers”, Trends Anal. Chem. 30(10): 1560-1567 (2011). |
| Ramsey Research Group, High Pressure Mass Spectrometry, Department of Chemistry, The University of North Carolina at Chapel Hill, Retrieved from the internet on May 28, 2014 at URL http://www.chem.unc.edu/people/faculty/ramsey/group/micro%20ion%20trap/High%20Pressure%20MS/High%20Pressure%20MS.html. |
| Ramsey Research Group, Microscale and High Pressure Mass Spectrometry, Department of Chemistry, The University of North Carolina at Chapel Hill, Retrieved from the internet on May 28, 2014 at URL http://www.chem.unc.edu/people/faculty/ramsey/group/micro_ms.html. |
| Schwartz et al. “A Two-Dimensional Quadrupole Ion Trap Mass Spectrometer”, jschwartz@thermofinnigan.com 2002. |
| Shiea, Jentaie, “Ionization methods for miniature mass spectrometers” Presentations at PITTCON 202, Orlando, FL, Mar. 14, 2012. |
| Sokol et al. “Miniature mass spectrometer equipped with electrospray and desorption electrospray ionization for direct analysis of organics from solids and solutions” Int. J. Mass Spectrom. 306: 187-195 (2011). |
| Song et al. “Novel Linear Ion Trap Mass Analyzer Composed of Four Planar Electrodes” AM Soc Mass Spectrom, Purdue University, 2006. |
| Song, Qingyu “Development of Mass Spectrometers using Rectilinear Ion Trap Analyzers” Ph.D. Thesis, Purdue University, 2008. |
| Syms, R.R.A. “Advances in microfabricated mass spectrometers”, Anal. Bioanal. Chem. 393: 427-429 (2009). |
| Taylor et al. “A Simplified Toroidal Ion Trap Mass Analyzer”, International Journal of Mass Spectrometry, 2012. |
| Telrandhe, Mangesh “Fabrication and testing of a cylindrical ion trap microarray for tunable mass spectrometers” M.S. Thesis, University of South Florida, 2004. |
| Van Amerom et al. “Microfabrication of Cylindrical Ion Trap Mass Spectrometer Arrays for Handheld Chemical Analyzers” Chem. Eng. Comm. 195: 98-114 (2008). |
| Wells et al. “A Quadrupole Ion Trap with Cylindrical Geometry Operated in the Mass-Selective Instability Mode” Anal. Chem. 70(3): 438-444, (1998). |
| Whitten et al. “High-pressure ion trap mass spectrometry”, Rapid Commu. Mass Spectrom. 18: 1749-1752 (2004). |
| Whitten et al. “Miniature Ion Traps and Arrays for High Pressure Mass Spectrometry”, HEMS Workshop 2005. |
| Wolfe D. et al. “High-Pressure Mass Spectrometry in Microscale Cylindrical Ion Traps”, Presented at 60th ASMS Conference on Mass Spectrometry and Allied Topics, Vancouver, Canada, May 24, 2012. |
| Wolfe et al. “RF amplifier optimization for improved resolution in microscale cylindrical ion traps” Presentation at 59th ASMS Conference 2011, Denver, CO, Jun. 5, 2011. |
| Xu et al. “Ion Trap Mass Analysis at High Pressure: A Theoretical View”, J. Am. Soc. Mass Spectrom, 20:2144-2153 (2009). |
| Xu et al. “Nondestructive Ion Trap Mass Analysis at High Pressure” Anal. Chem. 83(3):685-689 (2011). |
| Yang et al. “Development of a Palm Portable Mass Spectrometer” J. Am. Soc Mass Spectrom 2008. |
| Zhang et al. “Paul Trap Mass Analyzer Consisting of Opposing Microfabricated Electrode Pairs” Anal. Chem. 81: 5241-5248 (2009). |
| 908 Devices, 908 Devices Introduces World's First Handheld Mass Spectrometer, Published: Mar. 10, 2014. |
| Number | Date | Country | |
|---|---|---|---|
| 20170271139 A1 | Sep 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62010050 | Jun 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14734623 | Jun 2015 | US |
| Child | 15617089 | US |
