Patent Application
20250231142
The present teachings generally relate to methods and systems of analyzing ions utilizing differential mobility spectrometry and mass spectrometry (MS).
Mass spectrometry (MS) is an analytical technique for measuring the mass-to-charge ratios (m/z) of molecules within a sample, with both quantitative and qualitative applications. For example, mass spectrometry can be used to identify unknown compounds in a test substance, determine the isotopic composition of elements in a specific molecule, determine the structure of a particular compound by observing its fragmentation, and/or quantify the amount of a particular compound in a test sample. MS typically involves converting the sample molecules into ions using an ion source and separating and detecting the ionized molecules with electric and/or magnetic fields due to differences in their mass-to-charge ratios (m/z) using one or more mass analyzers. Depending on the experiment, ions generated by the ion source may be detected intact (generally referred to as MS) or alternatively may be subject to fragmentation as in tandem MS (also referred to as MS/MS or MS2) such that product ions resulting from the fragmentation of selected precursor ions may additionally or alternatively be detected.
Whereas MS typically separates ions based on their m/z at very low operating pressures (often as low as 10−5 Torr or lower), ion mobility based analytical techniques instead separate and analyze ions based upon differences in their mobility through a relatively high pressure gas. One example of such ion-mobility based techniques is differential mobility spectrometry in which a differential mobility spectrometer separates ions on the basis of an alpha parameter, which is related to the differences in the ion mobility coefficient in varying strengths of electric field. In some known differential mobility spectrometers, RF voltages, commonly referred to as separation voltages (SV) and also referred to as dispersion voltages, are applied across the drift tube in a direction perpendicular to that of the drift gas flow. Ions of a given species tend to migrate radially away from the axis of the transport chamber by a characteristic amount during each cycle of the RF waveform due to differences in mobility during the high field and low field portions. A DC potential, commonly referred to as a compensation voltage (COV or also referred to as CV), is applied to the differential mobility spectrometer and provides a counterbalancing electrostatic force to that of the SV. The COV can be tuned so as to preferentially prevent the drift of one or more species of ions of interest. Depending on the application, the COV can be set to a fixed value to pass only ion species with a particular differential mobility while the remaining species of ions drift toward the electrodes and are neutralized. Alternatively, if the COV is scanned for a fixed SV as a sample is introduced continuously into the differential mobility spectrometer, a mobility spectrum can be produced as the differential mobility spectrometer transmits ions of different differential mobilities. Examples of known differential mobility spectrometers are described in U.S. Pat. Nos. 8,084,736 and 9,835,588, the teachings of which are hereby incorporated by reference in their entireties. Differential mobility spectrometry devices that utilize curved ion paths are also known. For clarity the term, COV and CV as described are intended to refer to the same differential mobility parameter and are used interchangeably herein. Likewise, the terms separation voltage and dispersion voltage are intended to refer to the same differential mobility parameter and are used interchangeably herein.
While differential mobility spectrometry may be used on its own to analyze a sample, a differential mobility spectrometer may also be interfaced with a mass spectrometer to serve as a front end orthogonal separation method, thus taking advantage of the atmospheric pressure, gas phase, and continuous ion separation capabilities of differential mobility spectrometry to provide enhanced analytical power to the differential mobility spectrometry-MS/MS system. Such a differential mobility spectrometry-MS/MS system may enhance numerous areas of sample analysis, including proteomics, peptide/protein conformation, pharmacokinetic, metabolism analysis, trace level explosives detection, and petroleum monitoring, all by way of non-limiting example.
There remains a need for improved methods and systems for utilizing differential mobility spectrometry prior to MS/MS.
The present teachings are generally directed to improved methods and systems for differential mobility spectrometry.
In some conventional workflows utilizing differential mobility spectrometry-MS/MS, product ions resulting from the fragmentation of precursor ions transmitted by the differential mobility spectrometry at each of a plurality of SV-COV combinations are iteratively detected. However, in such conventional methods, data regarding the COV distribution of the precursor ions is typically left uncaptured. While one could, for example, utilize a differential mobility spectrometry-MS sample run at each SV-COV combination to identify the precursor ions transmitted by the differential mobility spectrometry device at the particular SV-COV combinations, such an approach would significantly increase the total analytical time for a given batch of samples. For example, when front-end liquid chromatography (LC) separation techniques are performed prior to differential mobility spectrometry-MS/MS, decreases in the duty cycle of differential mobility spectrometry-MS/MS analysis may reduce the total amount of data that can be obtained from each sample within the LC time scale.
In accordance with various aspects of the present teachings, methods and systems described herein allow for the simultaneous determination of precursor information and MS/MS data at each SV-COV combination, for example. In various aspects, the present teachings provide that MS data can be derived and/or inferred from MS/MS data obtained for each of a plurality of SV-COV combinations applied to a sample, without requiring a separate differential mobility spectrometry-MS run each time the COV is stepped, for example.
Certain aspects of the present teachings provide a method for analyzing ions, comprising determining intensities and mass-to-charge ratios (m/z) of a population of analyte ions transmitted through a differential mobility spectrometry device operating in a transmission mode in which ion mobility filtering is disabled prior to the transmitted ions being mass analyzed. For example, in transmission mode (e.g., disabled mode) for the device depicted in
In various aspects, identifying which of the population of analyte ions are present in each of the plurality of product ion scans obtained at different SV-COV combinations may comprise correlating the determined m/z of the population of analyte ions with the m/z of the product ion scan at each SV-COV combination.
In certain aspects, identifying which of the population of analyte ions are present in each of the plurality of product ion scans obtained at different SV-COV combinations may comprise multiplying a value indicative of the intensity at each determined m/z of the population of analyte ions by a value indicative of the intensity at each corresponding m/z of the product ion scan. In some related aspects, the value indicative of the intensity at each determined m/z of the population of analyte ions may comprise the determined intensity. Alternatively, in some related aspects, the value indicative of the intensity at each m/z of the product ion scan may be determined based relative to a threshold. For example, in certain aspects, the value indicative of the intensity at each m/z of the product ion scan may be assigned one of two binary values based on the intensity at each m/z of the product ion scan relative to the threshold.
As noted above, methods in accordance with the present teachings may include obtaining a product ion scan comprising intensities and m/z of a set of product ions for each of a plurality of SV-COV combinations. In some example aspects, obtaining the product ion scan may further comprise mass filtering the set of precursor ions transmitted through the enabled differential mobility spectrometry device to select a subset of precursor ions, and further, subjecting the subset of precursor ions to fragmentation. By way of non-limiting example, the subset of precursor ions may comprise ions of the set of precursor ions transmitted through the enabled differential mobility spectrometry device in a range of about 50 m/z or greater, which may be adjusted based on the application need. For instance, in a digest peptide analysis, the ions selected by the mass filter range could exhibit about 500 m/z or greater.
In certain aspects, the population of analyte ions and each set of precursor ions may be obtained from a liquid chromatography sample at approximately the same elution time. Additionally or alternatively, in some example aspects, the population of analyte ions and each set of precursor ions may be obtained from a liquid chromatography sample during a first elution time range in which a composition of the liquid chromatography sample is substantially identical. In some related aspects, the method may further comprise identifying which of a second population of analyte ions are present in each of a second plurality of product ion scans obtained at a plurality of SV-COV combinations from a second plurality of sets of precursor ions, wherein the second population of analyte ions and each of the second plurality of sets of precursor ions are obtained from the liquid chromatography sample during a second elution time range in which the composition of the liquid chromatography sample differs from the composition of the liquid chromatography sample during the first elution time range.
Certain aspects of the present teachings provide a system for analyzing ions, the system comprising a differential mobility spectrometry device for separating ions based on their differential mobilities and a tandem mass spectrometer for receiving ions transmitted from the differential mobility spectrometry device, the tandem mass spectrometer comprising a mass filter, a fragmentation device, and a mass analyzer. The system may also comprise a control system operatively coupled to the differential mobility spectrometry device and the tandem mass spectrometer, the control system comprising a processor and a memory including program code configured to, when executed, cause the processor to: determine intensities and mass-to-charge ratios (m/z) of a population of analyte ions transmitted through the differential mobility spectrometry device when operating in transmission or disabled mode and apply a separation voltage (SV) and a compensation voltage (COV) to the differential mobility spectrometry device to enable the differential mobility spectrometry device. The processor may also be caused to iteratively perform the following steps: (a) transmit a plurality of ions through the enabled differential mobility spectrometry device having a SV-COV combination applied thereto so as to select a set of precursor ions based on their differential mobility; (b) fragment at least a portion of the set of precursor ions so as to form a set of product ions; (c) obtain a product ion scan identifying intensities and m/z of at least a portion of the set of product ions; and (d) adjust at least one of the SV and COV applied to the enabled differential mobility spectrometry device. The processor may further be caused to identify which of the population of analyte ions, if any, are present in each of the plurality of product ion scans obtained at different SV-COV combinations.
In various aspects, when the processor is caused to identify which of the population of analyte ions are present in each of the plurality of product ion scans obtained at different SV-COV combinations, the processor is caused to correlate the determined m/z of the population of analyte ions with the m/z of the product ion scan at each SV-COV combination.
In certain aspects, when the processor is caused to identify which of the population of analyte ions are present in each of the plurality of product ion scans obtained at different SV-COV combinations, the processor is caused to multiply a value indicative of the intensity at each determined m/z of the population of analyte ions by a value indicative of the intensity at each corresponding m/z of the product ion scan. In some related aspects, the value indicative of the intensity at each determined m/z of the population of analyte ions may comprise the determined intensity. In some aspects, the value indicative of the intensity at each m/z of the product ion scan may be determined based relative to a threshold. In some related aspects, the value indicative of the intensity at each m/z of the product ion scan may be assigned one of two binary values based on the intensity at each m/z of the product ion scan relative to the threshold.
In various aspects, the at least a portion of the set of precursor ions that are fragmented may comprise a subset of precursor ions mass filtered by the mass analyzer. For example, the subset of precursor ions may comprise ions of the set of precursor ions having about 50 m/z or greater (e.g., 500 m/z or greater).
In various aspects, the population of analyte ions and each set of precursor ions may be obtained from a liquid chromatography sample at approximately the same elution time. For example, in some aspects, the population of analyte ions and each set of precursor ions may be obtained from a liquid chromatography sample during a first elution time range in which a composition of the liquid chromatography sample is substantially identical.
These and other features of the applicant's teachings are set forth herein.
The skilled person in the art will understand that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the applicant's teachings in any way.
It will be appreciated that for clarity, the following discussion will explicate various aspects of embodiments of the applicant's teachings, while omitting certain specific details wherever convenient or appropriate to do so. For example, discussion of like or analogous features in alternative embodiments may be somewhat abbreviated. Well-known ideas or concepts may also for brevity not be discussed in any great detail. The skilled person will recognize that some embodiments of the applicant's teachings may not require certain of the specifically described details in every implementation, which are set forth herein only to provide a thorough understanding of the embodiments. Similarly, it will be apparent that the described embodiments may be susceptible to alteration or variation according to common general knowledge without departing from the scope of the disclosure. The following detailed description of embodiments is not to be regarded as limiting the scope of the applicant's teachings in any manner.
As used herein, the terms “about” and “substantially equal” refer to variations in a numerical quantity that can occur, for example, through measuring or handling procedures in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of compositions or reagents; and the like. Typically, the terms “about” and “substantially” as used herein mean 10% greater or lesser than the value or range of values stated or the complete condition or state. For instance, a concentration value of about 30% or substantially equal to 30% can mean a concentration between 27% and 33%. The terms also refer to variations that would be recognized by one skilled in the art as being equivalent so long as such variations do not encompass known values practiced by the prior art.
Systems and methods in accordance with various aspects of the present teachings enable the determination of precursor information (e.g., MS data) and MS/MS data for a plurality of SV-COV combinations applied to a differential mobility spectrometer, for example, without having to utilize a separate differential mobility spectrometry-MS sample run for each of the plurality of SV-COV combinations. Whereas conventional differential mobility spectrometry-MS/MS workflows fail to capture COV information associated with the precursor ions and/or require a differential mobility spectrometry-MS sample run for each SV-COV combination to identify the precursor ions transmitted for each COV, various aspects of the present teachings provide for the determination of increased MS data without substantially increasing the analytical time. In various aspects, the present teachings provide that MS data can be derived and/or inferred from MS/MS data obtained for each of a plurality of SV-COV combinations applied to a sample, without requiring a separate differential mobility spectrometry-MS run each time the COV is adjusted, for example.
In the exemplary embodiment depicted in
As indicated by the arrows of
By way of example, in certain aspects, a separation voltage (SV) and a compensation voltage (COV) can be applied to the differential mobility spectrometry device 132, when enabled, so as to perform differential mobility separation on the ions within the drift gas flowing through the analytical gap 136 between the parallel plate electrodes 134a,b. The SV, for example, may be an RF voltage signal applied to the electrodes 134a,b so as to generate an electric force across the analytical gap 136 (e.g., perpendicular to the central axis of the analytical gap 136) such that ions of various species migrate radially away from the axis of the transport chamber by a respective characteristic amount during each cycle of the RF waveform due to differences in their respective mobilities during the high field and low field portions of the RF signal. On the other hand, the COV, which may be a DC potential applied across the analytical gap 136, can provide a counterbalancing electrostatic force to that of the SV. In this manner, the COV can be tuned so as to preferentially restore a stable trajectory to particular ions such that they will traverse the entire length of the analytical gap 136 and be transmitted through inlet 150a.
The SV-COV combination may be adjusted in a variety of manners such that one or more species of ions may be transmitted from the differential mobility spectrometry device 132 into the inlet 150a as their drift therethrough does not cause them to be neutralized at the electrodes 134a,b. By way of example, in various aspects, the SV can be fixed at a value while the COV is adjusted (e.g., scanned) to serially pass ions exhibiting a particular differential mobility so as to generate a mobility spectrum. Alternatively, in some example aspects, a mobility spectrum may be generated by setting the COV to a fixed value while the SV is scanned so as to serially pass ions of interest. In some aspects, the differential mobility spectrometry device 132 may be operated with both the COV and SV fixed such that only ion species with a particular differential mobility are transmitted through from the differential mobility spectrometry device 132 while the remaining species of ions drift toward the electrodes 134a,b and are neutralized. Examples of differential mobility spectrometers which may be modified for use in accordance with the present teachings are described, for example, in U.S. Pat. Nos. 8,084,736 and 9,835,588, the teachings of which are hereby incorporated by reference in their entireties.
In various aspects, the computer system 180 may cause the differential mobility spectrometry device 132 to alternatively operate in a mode in which the differential mobility spectrometry device 132 is configured to not filter and/or not separate ions based on their differential mobilities (e.g., substantially all ions received from the ion source 104 are configured to be transmitted therethrough without being neutralized on the plates 134a,b). Such a “transmission mode” or “disabled mode” may be effectuated, for example, by the computer system 180 causing no SV or no differential DC voltages to be applied the plates 134a,b of the differential mobility spectrometry device 132 (e.g., SV=COV=0 V). It will be appreciated, for example, that when operating the differential mobility spectrometry device 132 in such a transmission mode, DC voltages applied to the electrode plates 134a,b may alternatively represent a symmetric non-zero offset value of the same polarity to the ions of interest so as to generate a substantially radially-inward force (e.g., toward the central axis) on the ions as they are transmitted between the electrode plates 134a,b.
In accordance with certain aspects of the present teachings, the curtain gas can be set to flow rates determined by a flow controller and valves so as to alter the drift time of ions within the differential mobility spectrometry device 132. Additionally, in some aspects, a throttle gas supply (not shown) can provide a throttle gas to the outlet end of the differential mobility spectrometry device 132 so as to modify the flow rate of the drift gas through the differential mobility spectrometry device 132 as described, for example, in U.S. Pat. Nos. 8,084,736, 8,513,600, and 9,171,711, all of which are incorporated herein by reference. Each of the curtain gas supply 133 and throttle gas supply (not shown) can provide the same or different pure or mixed composition gas to the curtain gas chamber. By way of non-limiting example, the curtain gas can be air, O2, He, N2, or CO2. The pressure of the curtain chamber 130 can be maintained, for example, at or near atmospheric pressure (i.e., 760 Torr).
Additionally, in some aspects, the system 100 can include a chemical modifier supply (not shown) for supplying a chemical modifier and/or reagent (hereinafter referred as chemical modifier) to the curtain and throttle gases. As will be appreciated by a person skilled in the art, the modifier supply can be a reservoir of a solid, liquid, or gas through which the curtain gas is delivered to the curtain chamber 130. By way of example, the curtain gas can be bubbled through a liquid modifier supply. Alternatively, a modifier liquid or gas can be metered into the curtain gas, for example, through an LC pump, syringe pump, or other dispensing device for dispensing the modifier into the curtain gas at a known rate. For example, the modifier can be introduced using a pump so as to provide a selected concentration of the modifier in the curtain gas. The modifier supply can provide any modifier known in the art including, by way of non-limiting example, water, volatile liquid (e.g., methanol, propanol, acetonitrile, ethanol, acetone, and benzene), including alcohols, alkanes, alkenes, halogenated alkanes and alkenes, furans, esters, ethers, aromatic compounds. As will be appreciated by a person skilled in the art in light of the present teachings, the chemical modifier can interact with the ions 103 such that the ions differentially interact with the modifier (e.g., cluster via hydrogen or ionic bonding) during the high and low field portions of the SV, thereby effecting the COV needed to counterbalance a given SV. In some cases, this can increase the separation between the ion species.
The ions 103 emitted into the curtain chamber 130 via curtain chamber inlet 130a can be generated by any known or hereafter developed ion source for generating ions and modified in accordance with the present teachings. Non-limiting examples of ion sources suitable for use with the present teachings include atmospheric pressure chemical ionization (APCI) sources, electrospray ionization (ESI) sources, continuous ion source, a pulsed ion source, an inductively coupled plasma (ICP) ion source, a matrix-assisted laser desorption/ionization (MALDI) ion source, a glow discharge ion source, an electron impact ion source, a chemical ionization source, or a photo-ionization ion source, among others.
In the example depicted in
Additionally, as shown in
Although ions are depicted in
Ions transmitted into the vacuum chamber 150 via inlet 150a can enter the mass filter 152 (also referred to herein as Q1). As will be appreciated by a person of skill in the art, the mass filter 152 can be operated as a conventional transmission RF/DC quadrupole mass filter that can be operated to select an ion of interest and/or a range of ions of interest. For example, the computer system 180 can cause suitable RF/DC voltages to be applied to the mass filter 152 so as to operate in a mass-resolving mode. As should be appreciated, taking the physical and electrical properties of mass filter 152 into account, parameters for an applied RF and DC voltage can be selected so that mass filter 152 establishes a transmission window of chosen m/z ratios, such that these ions can traverse Q1 largely unperturbed. Ions having m/z ratios falling outside the window, however, do not attain stable trajectories within the quadrupole and can be prevented from traversing the mass filter 152. It should be appreciated that this mode of operation is but one possible mode of operation for mass filter 152. By way of example, one or more ion optical elements (not shown) between the mass filter 152 and the fragmentation device 154 can be maintained at a much higher offset potential than mass filter 152 such that Q1 can be operated as an ion trap. In such a manner, the potential applied to the ion optical elements (not shown) can be selectively lowered (e.g., mass selectively scanned) such that ions trapped in mass filter 152 can be accelerated into fragmentation device 154, which could also be operated as an ion trap, for example.
Ions transmitted by the mass filter 152 enter into the adjacent fragmentation device 154, which can be disposed in a pressurized compartment and can be configured to operate as a collision cell at a pressure approximately in the range of from about 1 mTorr to about 10 mTorr, though other pressures can be used for this or for other purposes. A suitable collision gas (e.g., nitrogen, argon, helium, etc.) can be provided by way of a gas inlet (not shown) to thermalize and/or fragment ions within the ion beam. By way of example, when in MS/MS mode, the mass filter 152 can be operated to transmit to fragmentation device 154 precursor ions exhibiting a selected range of m/z for fragmentation into product ions within fragmentation device 154. In MS mode, however, a person skilled in the art will appreciate that the parameters for RF and DC voltages applied to rods of the fragmentation device 154 can be selected so that the fragmentation device 154 transmits these ions therethrough largely unperturbed.
Ions that are transmitted by fragmentation device 154 can pass into the adjacent mass analyzer 156, which can again be operated at a decreased operating pressure relative to that of fragmentation device 154, for example, less than about 1×10−4 Torr (e.g., about 5×10−5 Torr), though other pressures can be used for this or for other purposes. As will be appreciated by a person skilled in the art, mass analyzer 156 can be operated in a number of manners, for example, as a scanning RF/DC quadrupole, as a linear ion trap, or as a RF-only ion guide to allow the ions to pass therethrough unperturbed. Indeed, suitable mass analyzer 156 for use in accordance with the present teachings include a time-of-flight (TOF) device, a quadrupole, an ion trap, a linear ion trap, an orbitrap, a magnetic four-sector mass analyzer, a hybrid quadrupole time-of-flight (Q-TOF) mass analyzer, or a Fourier transform mass analyzer, all by way of non-limiting example. In some aspects, for example, mass analyzer 156 can be operated as an ion trap for trapping ions received from the fragmentation device 154, with the potentials applied to exit ion optical elements (not shown) being selectively lowered such that ions trapped within mass analyzer 156 can be transmitted in a mass-selective manner to detector 158, which generates ion detection signals in response to the incident ions.
The computer system 180, which is in communication with the detector 158, may receive and process the ion detection signals to generate a mass spectrum of ions, for example, indicating the amount of ions (e.g., intensity, count) of each m/z that were transmitted by the mass analyzer 156.
Computer system 280 may be coupled via bus 281 to a display 286, such as a cathode ray tube (CRT) or liquid crystal display (LCD), for displaying information to a computer user. An input device 287, including alphanumeric and other keys, is coupled to bus 622 for communicating information and command selections to processor 282. Another type of user input device is cursor control 288, such as a mouse, a trackball or cursor direction keys for communicating direction information and command selections to processor 282 and for controlling cursor movement on display 286. This input device typically has two degrees of freedom in two axes, a first axis (i.e., x) and a second axis (i.e., y), that allows the device to specify positions in a plane.
A computer system 280 can perform the present teachings. Consistent with certain implementations of the present teachings, results are provided by computer system 280 in response to processor 282 executing one or more sequences of one or more instructions contained in memory 283. Such instructions may be read into memory 283 from another computer-readable medium, such as storage device 285. Execution of the sequences of instructions contained in memory 283 causes processor 282 to perform the process described herein. Alternatively, hard-wired circuitry may be used in place of or in combination with software instructions to implement the present teachings. Thus, implementations of the present teachings are not limited to any specific combination of hardware circuitry and software. For example, the present teachings may be performed by a system that includes one or more distinct software modules for perform a method for analyzing ions in accordance with various embodiments (e.g., a differential mobility spectrometry module, a mass filter module, a fragmentation module, an analyzer module).
In various embodiments, computer system 280 can be connected to one or more other computer systems, like computer system 280, across a network to form a networked system. The network can include a private network or a public network such as the Internet. In the networked system, one or more computer systems can store and serve the data to other computer systems. The one or more computer systems that store and serve the data can be referred to as servers or the cloud, in a cloud computing scenario. The one or more computer systems can include one or more web servers, for example. The other computer systems that send and receive data to and from the servers or the cloud can be referred to as client or cloud devices, for example.
The term “computer-readable medium” as used herein refers to any media that participates in providing instructions to processor 282 for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device 285. Volatile media includes dynamic memory, such as memory 283. Transmission media includes coaxial cables, copper wire, and fiber optics, including the wires that comprise bus 281.
Common forms of computer-readable media or computer program products include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, digital video disc (DVD), a Blu-ray Disc, any other optical medium, a thumb drive, a memory card, a RAM, PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, or any other tangible medium from which a computer can read.
Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to processor 282 for execution. For example, the instructions may initially be carried on the magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system 280 can receive the data on the telephone line and use an infra-red transmitter to convert the data to an infra-red signal. An infra-red detector coupled to bus 281 can receive the data carried in the infra-red signal and place the data on bus 281. Bus 281 carries the data to memory 283, from which processor 282 retrieves and executes the instructions. The instructions received by memory 283 may optionally be stored on storage device 285 either before or after execution by processor 282.
As noted above, systems and methods in accordance with various aspects of the present teachings enable the determination of MS data from MS/MS data obtained for each of a plurality of SV-COV combinations applied to a sample, without requiring a separate differential mobility spectrometry-MS run each time the combination of SV-COV is adjusted. With reference now to
Thereafter, in step 320, a first combination of SV-COV may be applied to enable the differential mobility spectrometry device to transmit at least a portion of the ions received by the differential mobility spectrometry device. By way of example, only a portion of the ions received by the differential mobility spectrometry device may exhibit a stable trajectory along the entire length of the differential mobility spectrometry device so as to be transmitted into one or more downstream elements for further processing. Such ions transmitted by the differential mobility spectrometry device are designated as first set of “precursor ions” as such ions transmitted by the differential mobility spectrometry are subjected to fragmentation conditions, for example, within fragmentation device 154 of
As shown in
The total ion scan obtained with the differential mobility spectrometry device operating in transmission or disabled mode and the plurality of product ion scans operating with various SV-COV combinations applied thereto can be obtained in any order, although they are preferably obtained when the composition of the sample specimen subject to methods described herein is substantially the same. By way of example, another exemplary method 400 for performing differential mobility spectrometry-MS/MS in accordance with various aspects of the present teachings is depicted. The method 400 is similar to the method 300 discussed above, but differs in that at least one total ion scan to which the product ion scans are compared is obtained after the plurality of the product ion scans obtained at various SV-COV combinations. By way of example, a total ion scan is obtained in step 420 after at least two product ion scans have been obtained at various SV-COV combinations in step 410.
Additionally, the example method 400 depicted in
Comparing total ion scans obtained in step 420 and step 440, each of which potentially represents a population of analyte ions from specimens of different compositions, may be especially beneficial when the ions received by the differential mobility spectrometry device are derived from a specimen of a sample separation device that is configured to separate one or more compounds from a sample over time (e.g., as with an in-line LC column). In this manner, if a comparison of the total ions scans obtained from specimens that elute at different times indicate a change in the composition of the eluent, a new set of product ion scans associated with the second specimen may be obtained. However, it will additionally be appreciated that a comparison between the first and second total ion scans is not necessary, for example, if a change in the sample composition is previously known. For example, if a user or the system has a priori knowledge of the elution profile, the timing for obtaining a first total ion scan (and the corresponding first plurality of product ion scans for comparison therewith) and for obtaining a second total ion scan (and the corresponding second plurality of product ion scans for comparison therewith) may be pre-determined.
With reference now to
With reference now to
It will be appreciated that the differential mobility spectrometry conditions can be changed any number of times, for example, and product ions may be iteratively obtained at various SV-COV combinations. For example,
Similarly, as shown in
The descriptions herein of various implementations of the present teachings have been presented for purposes of illustration and description. It is not exhaustive and does not limit the present teachings to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practicing of the present teachings. Additionally, the described implementation includes software, though the present teachings may be implemented as a combination of hardware and software or in hardware alone. The present teachings may be implemented with both object-oriented and non-object-oriented programming systems.
The section headings used herein are for organizational purposes only and are not to be construed as limiting. While the applicant's teachings are described in conjunction with various embodiments, it is not intended that the applicant's teachings be limited to such embodiments. On the contrary, the applicant's teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/059831 | 10/13/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63256825 | Oct 2021 | US |
