Mass spectrometry is an analytical method used to identify compounds based on their molecular weight and fragmentation pattern, which provides a molecular fingerprint. Lasers can be used to produce photons and irradiate the ions, causing the ions to fragment in a process called photodissociation (PD). Depending on the operational wavelength of the laser, ultraviolet PD (UVPD) and infrared multiphoton PD (IRMPD) processes can be used to dissociate the ions. Mass spectrometry uses lasers that are normally positioned outside of the vacuum chamber of the mass spectrometer. The location of the laser typically requires special optics and flanges to guide photons into the irradiation area during conventional UVPD of gas-phase ions.
Because of the optics and flanges, the lasers may need to be aligned, and in many cases collimated or otherwise focused, to restrict the laser beam to a prescribed path in the mass spectrometer and to minimize damage to other components. Additionally, lasers require an optical port and optical access to the ion population (often constrained in a trapping cell within a vacuum chamber), and optical components such as lenses must be integrated in a manner that is stable to facilitate alignment and overlap of the laser generated radiation with the ion population.
Also, because a laser produces collimated light with minimal divergence, the resulting laser beam is typically arranged to align with the central axis of an ion beam or trapped ions in order to obtain the highest overlap between ions and photons. Other orientations of the laser beam require extra precision in timing and optimization to obtain an overlap with ions passing through the laser beam. Additionally, lasers are costly and may require auxiliary gases and/or cooling units and associated plumbing to operate effectively. Moreover, the structural magnitude, configuration complexity, and expense of a monochromatic laser may present technical challenges to pursuing ion processing strategies that involve the irradiation of ions with radiation at multiple wavelengths.
Therefore, a need exists for a PD device, and related systems and methods, that can take advantage of the versatile applications of PD and overcome the associated challenges of laser-based designs.
Overview
Examples of embodiments described herein include systems, methods, and devices for disassociating ions. In one example, a mass spectrometer for ion dissociation includes an ion source for providing ions for dissociation, a mass analyzer, and a photodissociation (PD) device. The PD device includes an ion transport device. The ion transport device is configured perform one or more of: transporting the ions through the PD device, and trapping the ions within a region of the PD device. The PD device also includes one or more light emitting diodes (LEDs) positioned to irradiate the ions in the PD device, resulting in fragmentation of the ions.
In another example, a photodissociation (PD) device for use in a mass spectrometer includes an ion transport device. The ion transport device is configured perform one or more of: transporting ions into the PD device, transporting the ions within the PD device, transporting the ions to a mass analyzer of the mass spectrometer, and trapping the ions within a region of the PD device. The PD device also includes one or more light emitting diodes (LEDs) positioned to irradiate the ions in the PD device, resulting in fragmentation of the ions.
In another example, a method of dissociating ions in a mass spectrometer includes transporting ions to a first region of a photodissociation (PD) device. The method also includes performing a first dissociation technique on the ions. The method further includes transporting the ions from the first region to a second region of the PD device. The method also includes irradiating the ions in the second region using one or more light emitting diodes (LEDs), resulting in fragmentation of the ions.
1-4 depict a process of transporting and trapping ions in the PD device, according to exemplary embodiments.
Although the following detailed description makes reference to exemplary illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art and are contemplated as within the scope of the present disclosure and claims. Accordingly, it is intended that the claimed subject matter is provided its full breadth of scope and to encompass equivalents.
In exemplary embodiments of the present disclosure, systems, methods, and devices relate to a photodissociation (PD) device that utilizes light emitting diodes (LEDs), which can be used in mass spectroscopy. According to embodiments, a PD device with LEDS can be incorporated into a vacuum chamber of a mass spectrometer to perform dissociation of gas-phase ions. The LEDs are positioned or implanted in a chamber of the PD device of a mass spectrometer to allow a convenient mechanism by which to irradiate ions with photons to cause the ions to dissociate. The resulting fragmentation patterns are used to identify molecules and serve as a molecular fingerprint. Various dissociation techniques may be utilized or combined in a single device, including PD, UVPD, electron-transfer dissociation (ETD), electron-capture dissociation (ECD), collision induced dissociation (CID), and/or high-energy collision dissociation (HCD). Additionally, according to embodiments, the PD device is capable of moving ions into and out of the path of radiation emanating from LEDs to precisely control when dissociation occurs and to what extent. The LEDs can be ultraviolet LEDs, visible light LEDs, or infrared LEDs.
Because LEDs offer a relatively inexpensive, safe, and robust way to generate photons, the PD device incorporating the LEDs eliminates the need for a costly, relatively complex laser that can pose safety concerns. Additionally, LEDs are small light sources that can be positioned inside the mass spectrometer and alleviate the safety concerns of using external lasers to generate photons. Also, optimizing the position of gas-phase ions and increasing the concentration of the photons emitting from each LED into an area of high or highest intersection increases the efficiency of the system.
Additionally, because the PD device can utilize any current and future wavelength available from LEDs, including organic light emitting diodes (OLEDs), the PD device also can be applied to the dissociation of any small gas-phase ion undergoing mass spectrometry analysis not exclusive to but including, plasticizers, pharmaceuticals and compounds related to materials chemistry research. Also, depending on the wavelength and power output qualities, LEDs may be used for mass spectrometry analysis for a wide range of omics applications and gas-phase spectroscopy research. For example, due to its high energy deposition which results in the production of rich fragmentation patterns, UVPD has emerged as a powerful alternative type of ion processing method for characterization of molecules ranging from small molecules to peptides to nucleic acids to lipids to proteins.
As illustrated in
The mass analyzer 106 can be placed adjacent to the PD device 102 to analyze the ions after dissociation or fragmentation by the PD device 102. For example, the mass analyzer 106 can be positioned between the ion source 104 and the PD device 102. In this configuration, the ions from the ion source 104 can be transported into the PD device 102. After the PD process, the ions can be transported back out of the PD device 102 into the mass analyzer 106. In another exemplary arrangement, the mass analyzer 106 can be positioned adjacent to the PD device 102 opposite the ion source 104. In this configuration, the ions from the ion source 104 can be transported into the mass analyzer 106 from the ion source 104. During the PD process, the ions can flow through the PD device 102 and into the mass analyzer 106.
The chamber 107 includes an ion transport or containment device 108 and one or more light emitting diodes (LEDs) 110. The ion transport or containment device 108 is configured to transport or contain the ions, from the ion source 104 into the chamber 107, through an entry 111, to an irradiation region 112 inside the PD device 102. The LEDs 110 are positioned to direct radiation at the radiation region 112 so that the radiation, from the LEDs 110, converge at the radiation region 112.
The ion transport or containment device 108 can be constructed to connect to the entry 111 and positioned to travel the longitudinal length of the chamber 107. In some embodiments, the ion transport or containment device 108 can be contained within the chamber 107. In some embodiments, the ion transport or containment device 108 can extend outside of the chamber 107, for example, through the entry 111 and/or through an exit 113.
The ion transport or containment device 108 can be configured to transport ions from the ion source 104 into, out of, or contain within the chamber for irradiation by the LEDs 110. For example, in some embodiments, the ion transport or containment device 108 can be configured to transport the ions to the irradiation region 112 and hold, compress, or trap the ions at one or more localized regions in the chamber 107, for instance, the irradiation region 112, to facilitate the dissociation or fragmentation of the ions. Likewise, for example, in some embodiments, the ion transport or containment device 108 can be configured to flow the ions through the irradiation region 112 at a velocity that allows the dissociation or fragmentation of the ions.
The ion transport or containment device 108 is constructed of electrical components that generate electromagnetic fields along the longitudinal length of the ion transport device. The ion transport or containment device 108 can be configured to include voltages and potentials along the longitudinal length of the ion transport or containment device 108 in order transport and trap the ions. The ion transport or containment device 108 can be configured to include potential gradients along the longitudinal length of the ion transport or containment device 108 to control the velocity (i.e., speed and direction) of the ions within the chamber 107.
As illustrated in
In any of the exemplary embodiments, the mass spectrometer 100 can include one or more additional dissociation systems. The dissociation systems can be configured to work in cooperation with the PD device to dissociation ions. For example, the dissociation systems can be configured to perform dissociation techniques such as ultraviolet photodissociation (UVPD), infrared multiphoton photo dissociation (IRMPD), electron-transfer dissociation (ETD), electron-capture dissociation (ECD), collision induced dissociation (CID), and high-energy collision dissociation (HCD). As such, the additional dissociation systems can include any necessary hardware, software, and combination thereof to perform the dissociation techniques. The additional dissociation systems can be incorporated in the mass spectrometer 100, incorporated in the PD device 102 or 150, and combination thereof.
The LEDs 110 can be any type of LED that emits radiation at wavelengths ranging from infrared (IR) to ultraviolet (UV) in order to disassociate or fragment the ions from the ion source 104. In some embodiments, for example, one or more of the LEDs 110 can emit radiation in wavelengths ranging from about 10 nm to about 950 nm. In some embodiments, one or more of the LEDs 110 can emit radiation in a wavelength ranging from about 10 nm to about 380 nm (i.e., UV radiation). In some embodiments, one or more of the LEDs 110 can emit radiation in a wavelength ranging from about 255 nm to about 275 nm, for instance, about 255 nm, about 265 nm, and/or about 275 nm.
In some embodiments, one or more of the LEDs 110 can be configured to emit radiation in a different wavelength from other LEDs 110. For example, one or more of the LEDs 110 can emit IR radiation, one or more of the LEDs 110 can emit visible radiation, and/or one or more of the LEDs 110 can emit UV radiation. By using multiple wavelengths, the PD device 102 can perform ion dissociation processes that involve the irradiation of ions with radiation at multiple wavelengths.
In some embodiments, the LEDs 110 can include one or more lenses for focusing or spreading the light on the ions. In some embodiments, AC current can be applied to the LEDs 110 to produce pulsed light. In some embodiments, DC current can be applied to the LEDs 110 to produce a continuous beam of light. The continuous beam of light from the LEDs can be used, for example, where the ions flow through an ion guide without trapping. In some embodiments, LEDs 110 irradiation times can be adjusted—e.g. extended or increased—to regulate MS/MS efficiencies and the extent of ion fragmentation.
In embodiments, the LEDs 110 can be coupled to the walls of the chamber 107 and directed at the irradiation region 112. In some embodiments, for example, the LEDs 110 can be fixed to the walls of the chamber 107. In some embodiments, for example, the LEDs 110 can be movably coupled to walls of the chamber 107 to allow the LEDs 110 to be repositioned, manually, automatically, or combination thereof. For instance, the LEDs 110 can be coupled to the walls of the chamber 107 by gimbals, swivels, motors, and the like.
In some embodiments, a single LED 110 can be configured to include a single source of radiation. In some embodiment, a single LED 110 can be configured to include multiple sources of radiation. For example, a single LED 110 can include multiple radiation sources that each emits the same type of radiation, different types of radiation, or combination thereof.
Referring again to
As shown in
The PD device 400 further includes a plurality of LEDs. As shown, the plurality of LEDs can include a first pair of LEDs 424A and 424B, a second pair of LEDs 425A and 425B, a third pair of LEDs 426A and 426B, a fourth pair of LEDs 427A and 427B, a fifth pair of LEDs 428A and 428B, and a sixth pair of LEDs 429A and 429B. The plurality of LEDs can be positioned near the back end wall 414. The plurality of LEDs can be integrated within opposite lateral sidewalls 416, 418 of the chamber housing 402. In some embodiments, the plurality of LEDs can be integrated within the lateral sidewalls 416, 418. In some embodiments, the plurality of LEDs can be moveable coupled to the lateral sidewalls 416, 418.
As illustrated in
Additionally, although not shown, it is further contemplated that, in some examples, the plurality of LEDs can comprise at least one LED or at least one pair of LEDs integrated within the back end wall 414. Additionally, each LED can include multiple radiation sources.
As illustrated in
After the process begins, in 502, ions are transported to a PD device for dissociation or fragmentation. For example, referring to
In 504, the ions are irradiated with radiation from one or more LEDs. For example, referring to
In 506, one or more additional dissociation techniques can optionally be performed. The one or more additional dissociation techniques can include ultraviolet photodissociation (UVPD), infrared multiphoton photo dissociation (IRMPD), electron-transfer dissociation (ETD), electron-capture dissociation (ECD), collision induced dissociation (CID), and high-energy collision dissociation (HCD). In some embodiments, the one or more additional dissociation techniques can be performed by additional dissociation systems. In some embodiments, the one or more additional dissociation techniques can be performed by the PD device 102.
In some embodiments, the one or more additional dissociation techniques can be performed after the irradiation by the LEDs. In some embodiments, the one or more dissociation techniques can be performed the irradiation by the LEDs. In some embodiments, the one or more additional dissociation techniques can be performed as an alternative to the irradiation by the LEDs.
In 508, the ions are transported to a mass analyzer. For example, referring to
After, the process 500 can return to any point, repeat, or end. For example, the ions may need to undergo further dissociation or fragmentation or the process can be performed on new ions. In this example, the ion transport or containment device, for example, the ion transport or containment device 108 can transport the ions or new ions into the PD device, for example PD device 102.
After the process begins, in 552, it is determined whether a collisionally dissociation is performed on ions being transported in the PD device. If the dissociation is performed, in 554, a potential difference in a region of the PD device is increased of the PD device prior to transport into the PD device. For example, referring to
In 556, after collisional dissociation or if the collisional dissociation is not performed, the ions are transported and trapped in the region of the PD device. For example, referring to
In 558, it is determined whether the ions are irradiated with radiation from one or more LEDs. If the ions are not irradiated, in 560, the ions are transported from the region of the PD device to a mass analyzer region. For example, the ions can be transported to the mass analyzer 106 by changing the potential gradient in the PD device 102 or 150. In 562, mass analysis is performed on the ions.
If the ions are irradiated, in 564, the ions are transferred from the region to an irradiation region and held for a designated irradiation time. For example, referring to
In 566, the irradiation of the ions is finished and the ions are transported from the PD device to the mass analyzer region. For example, referring to
In 562, mass analysis is performed on the ions. After, the process 500 can return to any point, repeat, or end. For example, the ions may need to undergo further dissociation or fragmentation or the process can be performed on new ions. In this example, the ion transport or containment device, for example, the ion transport or containment device 108 can transport the ions or new ions into the PD device, for example PD device 102.
The following examples are being presented to further illustrate the exemplary processes and devices of the present disclosure and are not intended to limit the examples of the embodiments described above.
To demonstrate the utility of an ion photodissociation cell in accordance with the present disclosure, a model chemical specie, flavin mononucleotide (FMN), was processed using a PD device similar to PD device 400 in accordance with the present disclosure as described below. Fragment ions of m/z 243.2, 359.2, and 439.2 corresponding to losses of the side-chain, the phosphate group, and water, respectively, have been generated upon UVPD of protonated FMN, in addition to products of m/z 257.2 and 286.2 attributed to formation of lumiflavin and formyl-lumiflavin species, by a Q-ToF mass spectrometer equipped with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for 266 nm UVPD, as disclosed at The Analyst, 139, 6348-6351 (2014) in the publication being titled “UV photodissociation of trapped ions following ion mobility separation in a Q-ToF mass spectrometer” by Barran et al., which is hereby incorporated by reference.
An experimental PD device 1, similar to PD device 400, was used to process FMN and was outfitted with eight LEDs. A schematic representation of the orientations of the LEDs 602A-608B of the experimental PD device 1 are shown in
MS/MS spectra of protonated FMN using the experimental PD device 1 are shown in
As a gauge of the level of control over ion position and UVPD in experimental PD device 1, similar to PD device 400 described above, the photodissociation of protonated FMN was evaluated based on the position of the ion cloud in the experimental PD device 1. First protonated FMN was transferred into the experimental PD device 1 and held proximate to the front end region of the chamber for 1000 ms while the LEDs were irradiating an irradiation region proximate to the back end of the chamber, for example, as illustrated in
To optimize the slope of the DC potential gradient during compression of the ion cloud proximate to the back end of the chamber of experimental PD device 1, several trials of UVPD of protonated FMN were performed using DC potential gradients at varying slopes and the resulting spectra were monitored. The radiation time was kept constant for all trials at 500 ms.
The results were further evaluated by observing how the MS/MS efficiency varied with the change in slope of the DC potential gradient. The MS/MS efficiency, defined as:
where EMS/MS is MS/MS efficiency, Fi is the summed abundances of all fragment ions, and P0 is the abundance of the precursor ion prior to activation. MS/MS efficiencies are plotted in
To optimize irradiation time during compression of the ion cloud proximate to the back end of the chamber of the experimental PD device 1, several trials of UVPD of protonated FMN were performed using varying irradiation time periods and the resulting spectra were monitored. The slope of the DC potential gradient was kept constant for all trials at −0.46 V/mm.
MS/MS efficiencies were plotted in
The effect of both the irradiation pattern of the LED and its wavelength on the fragmentation efficiency of FMN were also investigated. Two different types of irradiation patterns originate from the two different LED types used. (See
UVPD of negatively-charged ions can also be useful for analysis of many classes of compounds, including nucleic acids and glycopeptides. To test the negative mode functionality of the experimental LED UVPD device similar to PD device 400 described above, triply deprotonated 5′-GCGCGA-3′ (an oligodeoxynuclotide) was trapped proximate to the back end of the chamber of experimental PD, as described above, and irradiated for 500 ms by all eight LEDs. The charge-reduced electron photodetachment ion was the dominant product, along with a minor w5 fragment ion as shown in
This description and the accompanying drawings that illustrate exemplary embodiments should not be taken as limiting. Various mechanical, compositional, structural, electrical, and operational changes can be made without departing from the scope of this description and the claims, including equivalents. In some instances, well-known structures and techniques have not been shown or described in detail so as not to obscure the disclosure. Like numbers in two or more figures represent the same or similar elements. Furthermore, elements and their associated features that are described in detail with reference to one embodiment may, whenever practical, be included in other embodiments in which they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment and is not described with reference to a second embodiment, the element may nevertheless be claimed as included in the second embodiment.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages, or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about,” to the extent they are not already so modified. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
While the teachings have been described with reference to examples of the embodiments thereof, those skilled in the art will be able to make various modifications to the described embodiments without departing from the true spirit and scope. The terms and descriptions used herein are set forth by way of illustration only and are not meant as limitations. It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. In particular, although the processes have been described by examples, the stages of the processes can be performed in a different order than illustrated or simultaneously. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in the detailed description, such terms are intended to be inclusive in a manner similar to the term “comprising.” As used herein, the terms “one or more of” and “at least one of” with respect to a listing of items such as, for example, A and B, means A alone, B alone, or A and B. Further, unless specified otherwise, the term “set” should be interpreted as “one or more.” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection can be through a direct connection, or through an indirect connection via other devices, components, and connections.
This description's terminology is not intended to limit the invention. For example, spatially relative terms—such as “front”, “back”, “top”, “bottom”, “proximal”, “distal”, and the like—may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., locations) and orientations (i.e., rotational placements) of a device in use or operation in addition to the position and orientation shown in the figures. For example, if a device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be “above” or “over” the other elements or features. Thus, the exemplary term “below” can encompass both positions and orientations of above and below. A device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The above description and associated figures teach the best mode of the invention. The following claims specify the scope of the invention. Note that some aspects of the best mode may not fall within the scope of the invention as specified by the claims. Those skilled in the art will appreciate that the features described above can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described above, but only by the following claims and their equivalents.
This application claims the benefit of U.S. Provisional Application No. 62/345,546, filed Jun. 3, 2016, the entire contents of which are incorporated herein.
This invention was made with government support under research grant CHE 1402753 awarded by National Science Foundation. The government has certain rights in the invention
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/US2017/035689 | 6/2/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2017/210560 | 12/7/2017 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
6919562 | Whitehouse | Jul 2005 | B1 |
7947948 | Schwartz | May 2011 | B2 |
8278619 | Makarov et al. | Oct 2012 | B2 |
8957369 | Makarov | Feb 2015 | B2 |
9123517 | Papanastasiou | Sep 2015 | B2 |
9209005 | Makarov | Dec 2015 | B2 |
9245723 | Makarov et al. | Jan 2016 | B2 |
20050127289 | Fuhrer | Jun 2005 | A1 |
20090134321 | Hoyes | May 2009 | A1 |
20100019144 | Schwartz et al. | Jan 2010 | A1 |
20100065733 | Bateman | Mar 2010 | A1 |
20100123075 | Dantus | May 2010 | A1 |
20100207023 | Loboda | Aug 2010 | A1 |
20130020481 | Makarov et al. | Jan 2013 | A1 |
20150364302 | Oleg et al. | Dec 2015 | A1 |
20180174815 | Bossmeyer | Jun 2018 | A1 |
20190265195 | Park | Aug 2019 | A1 |
Number | Date | Country |
---|---|---|
2389704 | Dec 2003 | GB |
2502155 | May 2020 | GB |
2006103412 | Oct 2006 | WO |
2007010272 | Jan 2007 | WO |
2017210560 | Dec 2017 | WO |
Entry |
---|
International Preliminary Report on Patentability and Written Opinion issued in Application No. PCT/US2017/035689 dated Dec. 4, 2018. |
Olsen et al., “Higher-energy C-trap dissociation for peptide modification analysis”, Nature Methods, vol. 4, No. 9, Sep. 2007. |
J. Brodbelt, “Photodissociation mass spectrometry: new tools for characterization of biological molecules”, Chem. Soc. Rev., 2014, 43, pp. 2757-2783. |
Shaw et al., “Complete Protein Characterization Using Top-Down Mass Spectrometry and Ultraviolet Photodissociation”, J. Am. Chem. Soc. 2013, 135, pp. 12646-12651. |
Cannon, et al., “Top-Down 193-nm Ultraviolet Photodissociation Mass Spectrometry for Simultaneous Determination of Polyubiquitin Chain Length and Topology”, Anal. Chem. 2015, 87, pp. 1812-1820. |
Cannon et al., “Hybridizing Ultraviolet Photodissociation with Electron Transfer Dissociation for Intact Protein Characterization”, Anal. Chem. 2014, 86, pp. 10970-10977. |
Holden et al., “Ultraviolet Photodissociation Induced by Light-Emitting Diodes in a Planar Ion Trap”, Angew. Chem 2016, 128, pp. 12605-12609. |
Supplemental Information for the Holden et al. article, 2016, S1-S10. |
International Search Report issued in Application No. PCT/US2017/035689 dated Aug. 25, 2017. |
Number | Date | Country | |
---|---|---|---|
20190295831 A1 | Sep 2019 | US |
Number | Date | Country | |
---|---|---|---|
62345546 | Jun 2016 | US |