Disambiguation of cyclic ion analyzer spectra

Abstract

Methods of operating an analytical instrument are provided, the analytical instrument comprising an ion analyzer, determining a drift time of an ion along an ion path, the ion path comprising a first segment and a cyclic segment, the ion path causing the ion to traverse the first segment a single time and the cyclic segment one or more times. The methods comprise: in a first mode: providing a first potential along the first segment, providing a second potential along the cyclic segment, the first segment having a first path length, the cyclic segment having a second path length, analyzing the ion by determining the drift time to obtain a first set of ion data; operating in a second mode by changing at least one of the first potential, the second potential, the first path length, and the second path length, analyzing the ion by determining the drift time to obtain a second set of ion data; comparing the first and second sets of ion data, identifying a first ion peak in the first set of ion data, determining a number of traversals of the ion based on the comparison; determining a physico-chemical property of the ion using the number of traversals.

Description

Technical Field

[0001] This invention relates to methods for analyzing ions, and more particularly to time-of-flight (ToF) mass analyzers and ion mobility analyzers. Background Technology

[0002] In time-of-flight (ToF) analyzers and ion mobility analyzers, ions travel through the analyzer's drift region and are eventually detected by a detector. The physicochemical properties of the ions, such as their mass-to-charge ratio (m / z) or ion mobility, are determined by the drift time of the ions through the drift region.

[0003] To improve the separation of analyte ions and to accurately determine their physicochemical properties (e.g., mass), it is generally desirable to increase the resolution of the analyzer. The resolution of an instrument is limited by the total length of the ion flight path through the analyzer (and other factors).

[0004] Several “looping” analysis techniques exist, which involve repeatedly cycling ions along the ion path within the analyzer. Increasing the number of loops N increases the length of the ion flight path within the analyzer, thereby increasing the analyzer's resolution.

[0005] However, during multiple cycles of N through the analyzer, lighter, faster-moving ions may catch up with (e.g., overlap) heavier, slower-moving ions. This complicates the resulting spectra and may make it difficult to accurately determine the physicochemical properties of all detected ions.

[0006] It is believed that there is still room for improvement in the methods of operating ion analyzers. Summary of the Invention

[0007] A first aspect provides a method for operating an analytical instrument, the analytical instrument including an ion analyzer configured to analyze ions by determining the drift time of ions along an ion path, the ion path including at least a first segment and a circulation segment, wherein the ion path is configured such that ions traverse the first segment once and traverse the circulation segment once or multiple times; the method includes:

[0008] The analyzer is operated in a first operating mode, wherein in the first operating mode: (i) a first potential is provided along a first segment of the ion path, (ii) a second potential is provided along a loop segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the loop segment of the ion path has a second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a first set of ion data.

[0009] The analyzer is operated in a second operating mode by changing at least one of (i) a first potential, (ii) a second potential, (iii) a first path length and (iv) a second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a second set of ion data.

[0010] The first set of ion data is compared with the second set of ion data, and the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data is identified.

[0011] Determine the number of times N, the loop segment of the ion path traversed by the ions associated with the corresponding first and second ion peaks; and

[0012] The determined number of crossings N is used to determine the physicochemical properties of the ions associated with the corresponding first and second ion peaks.

[0013] The implementation scheme relates to a method of operating a circulating ion analyzer. The analyzer is configured to analyze ions by determining (e.g., measuring) the drift time of ions along an ion path, where ions can pass through a circulating segment of the ion path multiple times before being detected. In a circulating analyzer, ions with very different physicochemical properties (e.g., mass-to-charge ratio (m / z) or ion mobility) can have similar drift times through the analyzer, for example, because faster-moving ions catch up with (e.g., overlap) slower-moving ions in the circulating segment of the ion path. This can complicate the resulting spectra and may make it difficult to accurately determine the physicochemical properties of the detected ions.

[0014] The implementation scheme provides a method for disambiguating spectra generated by a cyclic ion analyzer. As will be described in more detail below, by comparing two sets of ion data obtained using different analyzer settings, the number of times N of the ion path traversed by the ions contributing to the ion peak can be determined, thereby allowing the physicochemical properties of those ions to be assigned to the ion peak without ambiguity.

[0015] The analytical instrument may be a mass spectrometer, an ion mobility spectrometer, or a combination of both (e.g., a mass spectrometer including an ion mobility separator). The instrument may include an ion source. Ions may be generated from a sample in the ion source. Ions may be transferred from the ion source to the analyzer via one or more ion optics arranged between the ion source and the analyzer.

[0016] One or more ion optical devices may include any suitable arrangement of one or more ion directors, one or more lenses, one or more gates, etc. One or more ion optical devices may include one or more transfer ion directors for transferring ions, and / or one or more mass selectors or filters for mass selection of ions, and / or one or more ion-cooling ion directors for cooling ions, and / or one or more collision or reaction units for fragmenting or reacting ions, etc. One or more or each ion director may include multipolar ion directors (such as quadrupole ion directors, hexapole ion directors, etc.), segmented multipolar ion directors, stacked ring ion directors, etc.

[0017] An ion analyzer is configured to analyze ions by determining the drift time of ions along an ion path. Therefore, an ion analyzer may include an ion implanter disposed at the beginning of the ion path and an ion detector disposed at the end of the ion path. The ion implanter may be configured to receive ions from an ion source via one or more ion optics. The ion implanter may be configured to implant (receive) ions into the ion path (e.g., by accelerating ions along the ion path), so that the ions travel along the ion path to the detector. The ion implanter may be of any suitable form, such as an ion trap, or one or more (e.g., orthogonal) accelerating electrodes. Upon arrival at the detector, the ions can be detected by the detector, and their arrival time can be recorded by the detector, for example. The physicochemical properties of the ions, such as their mass-to-charge ratio and / or ion mobility, can then be determined based on the measured drift time.

[0018] The ion analyzer is a circulating analyzer. Therefore, the ion path includes circulating sections, where ions can traverse the circulating sections multiple times (repeatedly) as they travel along the ion path (from the ion implanter to the detector). The ion path also includes at least one first (non-circulating) section, where ions traverse the first section only once as they travel along the ion path (from the ion implanter to the detector). The first section can be directly adjacent to the circulating sections of the ion path (i.e., directly adjacent). The first section can be upstream or downstream of the circulating section.

[0019] The ion path may optionally include a second (non-cyclic) segment, wherein the ion traverses the second segment only once as it travels along the ion path (from the ion implanter to the detector). The second segment may be directly adjacent to the cyclic segment of the ion path (i.e., directly adjacent). The second segment may be upstream or downstream of the cyclic segment, for example, such that the ion path includes a first (non-cyclic) segment, a cyclic segment disposed downstream of the first segment, and a second (non-cyclic) segment disposed downstream of the cyclic segment.

[0020] Therefore, as ions travel along the ion path (from the ion implanter to the detector), the ions can traverse the first segment once before being detected by the detector, and then traverse the loop segment once or multiple times (e.g., multiple times), and optionally traverse the second segment once.

[0021] An ion analyzer can be a time-of-flight (ToF) mass analyzer configured to determine the mass-to-charge ratio (m / z) of ions based on their drift time, or an ion mobility analyzer configured to determine the ion mobility based on their drift time.

[0022] In this embodiment, the analyzer is a closed-loop multi-reflection ion trap mass analyzer. Therefore, the analyzer may include two ion mirrors spaced apart and opposite to each other in a first direction X, an ion implanter for implanting ions into the space between the ion mirrors, and a detector for detecting ions after they have undergone multiple reflections between the ion mirrors. The two ion mirrors may together form an ion trap. The two ion mirrors may be configured such that ions trapped in the ion trap will oscillate between the ion mirrors (in the first direction X), for example, oscillate indefinitely until these ions are released for detection. The entry and extraction of ions into the ion trap can be controlled by applying a suitable voltage to deflectors arranged in the region between the mirrors.

[0023] In these embodiments, the ion path can be configured such that ions traverse a first segment of the ion path once between the implanter and the deflector, then traverse a looping segment of the ion path multiple times between the ion mirrors, and subsequently traverse a second segment of the ion path once between the deflector and the detector.

[0024] In a particular embodiment, the analyzer is a multiple reflection time-of-flight (MR-ToF) analyzer, which may be configured to operate in a so-called “scale” operating mode. Therefore, the analyzer may include: two ion mirrors spaced apart and opposite each other in a first direction X, each mirror typically extending along a drift direction Y between a first end and a second end, the drift direction Y being orthogonal to the first direction X; an ion implanter positioned near the first end of the ion mirrors for implanting ions into the space between the ion mirrors; and a detector positioned near the first end of the ion mirrors for detecting ions after they have undergone multiple reflections between the ion mirrors.

[0025] The analyzer can be configured to analyze ions by the following operations:

[0026] (i) Ions are injected from an ion implanter into the space between ion mirrors, wherein the ions complete a first cycle in which the ions follow a zigzag ion path with multiple K reflections between the ion mirrors in the direction X, while: (a) drifting in the drift direction Y toward the second end of the ion mirror, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back in the drift direction Y toward the first end of the ion mirror;

[0027] (ii) Reverse the drift velocity of the ions near the first end of the ion mirror, causing the ions to complete another cycle in which the ions follow a zigzag ion path with multiple K reflections between the ion mirrors in the X direction, while: (a) drifting towards the second end of the ion mirror in the drift direction Y, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back towards the first end of the ion mirror in the drift direction Y;

[0028] (iii) Repeat step (ii) once or more; and subsequently

[0029] (iv) Cause the ions to travel to the detector for detection.

[0030] The analyzer may also include a deflector or lens positioned near the first end of the ion mirror. The analyzer can be configured to analyze ions by:

[0031] (i) Ions are injected from an ion implanter into the space between ion mirrors, wherein the ions complete a first cycle in which the ions follow a zigzag ion path with multiple K reflections between the ion mirrors in the direction X, while: (a) drifting from the deflector or lens toward the second end of the ion mirror in the drift direction Y, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back toward the deflector or lens in the drift direction Y;

[0032] (ii) Using a deflector or lens to reverse the drift direction velocity of the ions, causing the ions to complete another cycle in which the ions follow a zigzag ion path with multiple K reflections between the ion mirrors in the direction X, while: (a) drifting from the deflector or lens toward the second end of the ion mirror in the drift direction Y, (b) reversing the drift direction velocity near the second end of the ion mirror, and (c) drifting back toward the deflector or lens in the drift direction Y.

[0033] (iii) Repeat step (ii) once or more; and subsequently

[0034] (iv) Cause ions to travel from the deflector or lens to the detector for detection.

[0035] The deflector or lens can be positioned approximately equidistantly between the first and second ion mirrors (in the X direction). The deflector or lens can be arranged along the ion path after the first ion mirror reflection (in the first ion mirror) experienced by the ion beam after injection from the implanter, but before the second ion mirror reflection (in the second ion mirror). Correspondingly, the deflector or lens can be arranged along the ion path before the final ion mirror reflection (in the second ion mirror) experienced by the ion beam before reaching the detector, but after the penultimate ion mirror reflection (in the first ion mirror).

[0036] Multiple reflection time-of-flight (MR-ToF) quality analyzers can include any suitable type of MR-ToF. For example, the analyzer can include an MR-ToF with a set of periodic lenses configured to keep the ion beam focused along its flight path, for example, as described in the article by A. Verenchikov et al. in the Journal of Applied Solution Chemistry and Modeling, 2017, Vol. 6, pp. 1–22.

[0037] However, in certain embodiments, the analyzer is, for example, a tilting mirror type multi-reflection time-of-flight mass analyzer of the type described in U.S. Patent No. 9,136,101, the contents of which are incorporated herein by reference. Thus, the ion mirrors may be spaced apart from each other in the direction X by a non-constant distance along at least a portion of their length in the drift direction Y. The drift velocity of the ions toward the second end of the ion mirrors may be relative to the electric field generated by the non-constant distance between the two ion mirrors. This electric field may cause the ions to reverse their drift velocity near the second end of the ion mirrors and drift back toward the deflector in the drift direction.

[0038] Alternatively, the analyzer can be a single-focusing lens type multi-reflection time-of-flight mass analyzer of the type described, for example, in British Patent No. 2,580,089, the contents of which are incorporated herein by reference. Thus, the deflector can be a first deflector, and the analyzer can include a second deflector positioned near a second end of the ion mirror. The second deflector can be configured to cause ions to reverse their drift direction velocity near the second end of the ion mirror and drift back towards the deflector in the drift direction. For this purpose, a suitable voltage can be applied to the second deflector, for example, in the manner described in British Patent No. 2,580,089.

[0039] In one embodiment, the deflector may include one or more trapezoidal or prismatic electrodes arranged adjacent to the ion beam. The deflector is designed with a suitablely wide acceptance range so that an ion beam extending relatively broadly in the drift direction can be properly received and deflected by the deflector. The deflector may include a first trapezoidal or prismatic electrode arranged above the ion beam and a second trapezoidal or prismatic electrode arranged below the ion beam. The electrodes may be angled relative to the ion beam such that when a suitable (DC) voltage is applied to the electrodes, the resulting electric field induces deflection of the ion beam. A suitable deflection voltage is approximately ± several volts, ± tens of volts, or ± several hundred volts.

[0040] The deflector should (and in various embodiments) be configured such that it can cause the ion beam to be deflected at a desired (selected) angle. The angle at which the ion beam is deflected by the deflector can be adjustable, for example by adjusting the magnitude of the (DC) voltage applied to the deflector. The deflector can be configured such that it can deflect the ion beam at any desired angle.

[0041] In one embodiment, the method includes: injecting ions from an ion implanter into a space between ion mirrors. The ions may then be reflected in a first ion mirror and subsequently travel to a deflector. When the ions reach the deflector, the deflector may be configured not to deflect the ion beam (or to deflect the ion beam by a suitable small angle), for example, so as not to substantially change the drift direction velocity of the ions, such that the ions continue to cross the deflector and be reflected in a second ion mirror. This may include, for example, not applying a voltage or removing the voltage from the deflector (or applying a suitable small voltage to the deflector). The ions are then caused to complete a first cycle in which the ions follow a zigzag ion path with multiple (K) reflections between the ion mirrors in the direction X, while: (a) drifting from the deflector towards a second end of the ion mirror in the drift direction Y, (b) reversing the drift direction velocity near the second end of the ion mirror, and (c) drifting back towards the deflector in the drift direction Y.

[0042] After the ions have completed the first cycle, a deflector can be used to reverse the drift direction velocity of the ions, causing the ions to complete a second cycle in which they follow a zigzag ion path with multiple (K) reflections between the ion mirrors in direction X, while: (a) drifting from the deflector towards the second end of the ion mirror along the drift direction Y, (b) reversing the drift direction velocity near the second end of the ion mirror, and (c) drifting back towards the deflector along the drift direction Y. For this purpose, the deflector can be configured to deflect the ion beam, for example, by reversing the drift direction velocity of the ions. This can include, for example, applying a suitable voltage to the deflector during the period during which the ions are expected to return to the deflector. A suitable deflection voltage reversing the drift direction of the ions is approximately several hundred volts.

[0043] The step of reversing the drift direction velocity of ions using a deflector can be repeated once or multiple times. Therefore, the method may include: causing ions to complete multiple (N) cycles within the analyzer, in each cycle following a zigzag ion path with multiple (K) reflections between ion mirrors in direction X, while: (a) drifting from the deflector towards a second end of the ion mirror along the drift direction Y, (b) reversing the drift direction velocity near the second end of the ion mirror, and (c) drifting back towards the deflector along the drift direction Y. The first cycle can be initiated by injecting ions into the space between the ion mirrors, and after the ions have completed the first cycle, each subsequent cycle can be initiated by reversing the drift direction velocity of the ions using a deflector.

[0044] The method may include causing ions to travel from a deflector to a detector for detection. That is, after ions have completed a desired number (N) of cycles within the analyzer, ions may be allowed to travel from the deflector to the detector for detection. For this purpose, the deflector may be configured not to deflect the ion beam (or to deflect the ion beam by a suitably small angle), for example, so as not to substantially change the drift direction and velocity of the ions, allowing the ions to continue across the deflector, be reflected in a second ion mirror, and continue traveling to the detector. This may include, for example, not applying a voltage or removing the voltage from the deflector (or applying a suitably small voltage to the deflector), causing the ions to leave the deflector in a direction toward the detector. The ions may be reflected in one of the ion mirrors before traveling to the detector.

[0045] Upon arrival at the detector, the ion can be detected, for example, its arrival time can be recorded by the detector. The time of flight and / or mass-to-charge ratio of the ion can then be determined, optionally combined with information on the time of flight and / or mass-to-charge ratio of other ions, and a mass spectrum can be generated, for example. It should be noted that not all ions implanted into the analyzer can be detected by the detector, for example due to unavoidable losses at different points between the implanter and the detector and / or the inefficiency of the detector. Therefore, as used herein, the term "ion" should be understood to mean "some ions, most ions, or all ions".

[0046] In these embodiments, the ion path can be configured such that ions traverse a first segment of the ion path once between the implanter and the deflector or lens, then traverse a loop segment of the ion path multiple times between a first end and a second end of the ion mirror, and subsequently traverse a second segment of the ion path once between the deflector or lens and the detector.

[0047] In this method, the analyzer initially operates in a first operating mode, and while operating in the first operating mode, it analyzes ions (by determining the drift time of the ions along the ion path) to obtain a first set of ion data. The analyzer is then switched to a second operating mode, and while operating in the second operating mode, it analyzes ions (by determining the drift time of the ions along the ion path) to obtain a second set of ion data.

[0048] The first set of ion data may include multiple ion peaks. The number of times N, the cyclic segment of the ion path traversed by ions associated with some, most, or all of the ion peaks in the first set of ion data, may be (in itself) indefinite. Similarly, the second set of ion data may include multiple ion peaks, and the number of times N, the cyclic segment of the ion path traversed by ions associated with some, most, or all of the ion peaks in the second set of ion data, may be (in itself) indefinite. The first and second sets of ion data can be obtained by analyzing ions originating from the same sample (e.g., by analyzing ions generated from adjacent regions of the sample, and / or by analyzing ions generated from the sample at close (adjacent) time points), for example, such that ion peaks corresponding to some, most, or all (a large number of) ion peaks in the first set of ion data appear in the second set of ion data.

[0049] In the first operating mode, (i) a first potential is provided along a first segment of the ion path, (ii) a second potential is provided along a looping segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the looping segment of the ion path has a second path length. The first potential can be some, most, or all of the potentials provided along the first segment of the ion path. Similarly, the second potential can be some, most, or all of the potentials provided along the looping segments of the ion path. The first path length can be the path length of the entire first segment. The second path length can be the path length of a single loop (single circuit) of the ion within the looping segment of the ion path.

[0050] In the second operating mode, at least one of (i) the first potential, (ii) the second potential, (iii) the first path length, and (iv) the second path length is changed (modified) relative to the first operating mode. Therefore, the method may include switching the analyzer from the first operating mode to the second operating mode by at least one of the following operations: (i) changing the first potential, (ii) changing the second potential, (iii) changing the first path length, and (iv) changing the second path length. The changes can be made such that the alternating effect on the drift time of ions along the first segment is proportionally different from the alternating effect on the drift time of ions along the cyclic segment. Therefore, for example, in a particular embodiment, only one of (i) the first potential, (ii) the second potential, (iii) the first path length, and (iv) the second path length is changed (modified) relative to the first operating mode (and the other items are not changed between the first and second operating modes).

[0051] In a particular embodiment, where the analyzer is a multiple reflection time-of-flight (MR-ToF) mass analyzer (as described above), the method involves altering the second path length in the second operating mode by changing the number of reflections K of the ions between the ion mirrors as they follow a zigzag ion path. This can be accomplished by changing the angle at which the ion beam is deflected by the deflector, i.e., by changing the voltage applied to the deflector. A suitable deflection voltage offset for changing the beam angle in this way is approximately several volts or tens of volts.

[0052] Therefore, in the first operating mode, the analyzer can be configured such that in each cycle, ions are reflected by a first number K1 in direction X between the ion mirrors, while: (a) drifting from the deflector towards the second end of the ion mirror along the drift direction Y, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back towards the deflector along the drift direction Y. In the second operating mode, the analyzer can be configured such that in each cycle, ions are reflected by a second different number K2 in direction X between the ion mirrors, while: (a) drifting from the deflector towards the second end of the ion mirror along the drift direction Y, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back towards the deflector along the drift direction Y. The first number and the second number can differ by a small integer, such as 1, i.e., |K1-K2|=1.

[0053] In an alternative embodiment, the method includes changing some, most, or all of the first potential in a second operating mode. Thus, in the first operating mode, the analyzer may be configured to provide a first potential distribution along a first segment of the ion path, and in the second operating mode, the analyzer may be configured to provide a different potential distribution along the first segment of the ion path.

[0054] The first potential distribution and different potential distributions can be different, such that the electric field experienced by an ion traversing the first segment in the first operating mode is different from the electric field experienced by an ion traversing the first segment in the second operating mode. This difference can cause the flight time of an ion (with a specific m / z) along the first segment in the first operating mode to be different from the flight time of an ion (with the same specific m / z) along the first segment in the second operating mode. This flight time difference can depend on the mass-to-charge ratio (m / z) of the ion (e.g., proportional to it). Therefore, changing the first potential between the first and second operating modes can cause a mass-to-charge ratio-dependent flight time shift of an ion traversing the first segment between the first and second operating modes.

[0055] The first potential can be changed between the two operating modes in any suitable manner. For example, the instrument may include a flight tube arranged along at least a portion of a first segment of the ion path, and the method may include changing the first potential in the second operating mode by changing the voltage applied to the flight tube (relative to the voltage applied to the flight tube in the first operating mode).

[0056] Alternatively, the method may include altering a first potential in a second operating mode by changing the (pulsed) accelerating field provided by the ion implanter (e.g., by changing the (pulsed) extraction field provided within the ion implanter if the ion implanter is an ion trap). This can be accomplished by changing one or more (pulsed) accelerating voltages applied to one or more electrodes of the ion implanter. Thus, in a first operating mode, the ion implanter may be configured to accelerate ions along the ion path using a first accelerating field (one or more first accelerating voltages), and in a second operating mode, the ion implanter may be configured to accelerate ions along the ion path using a second, different accelerating field (one or more second, different accelerating voltages). A suitable accelerating field for the ion implanter is approximately several hundred V / mm, and a suitable accelerating field offset between the first and second operating modes is approximately tens of V / mm.

[0057] The method includes comparing a first set of ion data with a second set of ion data, for example, to identify a first ion peak in the first set of ion data that corresponds to a second ion peak in the second set of ion data. The method may include identifying multiple such corresponding ion peak pairs in the first and second sets of ion data. An ion peak may correspond to another ion peak because the ions that produce those peaks may have the same physicochemical properties (e.g., may be of the same class).

[0058] The identification of the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data may include an ion peak that identifies a value having physicochemical properties within a expected (e.g., small) range.

[0059] Alternatively, identifying the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data may include:

[0060] For each of one or more ion peaks in the first set of ion data, determine a first list of possible values ​​for the physicochemical properties that the ion associated with that ion peak may have.

[0061] For each ion peak in one or more ion peaks in the second set of ion data, a second list is determined of possible values ​​for the physicochemical properties that the ion associated with that ion peak may possess; and

[0062] The first list is compared with the second list, and based on this comparison, the ion peaks in the first set of ion data corresponding to the ion peaks in the second set of ion data are identified. This can be done by identifying ion peaks that have equal values ​​or physicochemical properties within the expected error range.

[0063] The method includes determining the number N of traversals of the looping segments of the ion path undertaken by the ions associated with corresponding first and second ion peaks (i.e., those generating the corresponding first and second ion peaks). This determination can be performed based on a comparison of a first set of ion data with a second set of ion data. For example, determining the number N of traversals of the looping segments of the ion path undertaken by the ions associated with the corresponding first and second ion peaks may include measuring the drift time difference between the first and second ion peaks and using the measured drift time difference to estimate the number N of traversals of the looping segments of the ion path undertaken by the ions associated with the corresponding first and second ion peaks.

[0064] The method involves using a determined number of crossovers N to determine the values ​​of the physicochemical properties of the ions associated with the corresponding first and second ion peaks (i.e., those that produce the corresponding first and second ion peaks). This process of determining the values ​​of the physicochemical properties of the corresponding ion peak pairs (based on the determined value of N) can be repeated for each identified corresponding ion peak pair of interest.

[0065] Another aspect provides a non-transitory computer-readable storage medium for storing computer software code that, when executed on a processor, performs the methods described above.

[0066] On the other hand, a control system for analytical instruments such as mass spectrometers and / or ion mobility spectrometers is provided, the control system being configured to cause the analytical instruments to perform the methods described above.

[0067] On the other hand, an analytical instrument, such as a mass spectrometer and / or an ion mobility spectrometer, is provided, which includes the control system described above.

[0068] On the other hand, an analytical instrument, such as a mass spectrometer and / or an ion mobility spectrometer, is provided, which includes:

[0069] An ion analyzer configured to analyze ions by determining the drift time of ions along an ion path, the ion path including at least a first segment and a circulation segment, wherein the ion path is configured such that ions traverse the first segment once and traverse the circulation segment once or multiple times; and

[0070] The control system is configured to:

[0071] In a first operating mode, the analyzer is operated and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a first set of ion data, wherein in the first operating mode, (i) a first potential is provided along a first segment of the ion path, (ii) a second potential is provided along a loop segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the loop segment of the ion path has a second path length.

[0072] The analyzer is operated in a second operating mode by changing at least one of (i) a first potential, (ii) a second potential, (iii) a first path length and (iv) a second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a second set of ion data.

[0073] The first set of ion data is compared with the second set of ion data, and the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data is identified.

[0074] Determine the number of times N, the loop segment of the ion path traversed by the ions associated with the corresponding first and second ion peaks; and

[0075] The determined number of crossings N is used to determine the physicochemical properties of the ions associated with the corresponding first and second ion peaks.

[0076] These aspects and implementations may (and indeed do) include any one or more optional features or each optional feature described herein.

[0077] For example, an ion analyzer can be a time-of-flight (ToF) mass analyzer, and the physicochemical property can be the mass-to-charge ratio (m / z).

[0078] Therefore, the analyzer may include:

[0079] Two ion mirrors are spaced apart and opposite each other in a first direction X. Each mirror typically extends along a drift direction Y between a first end and a second end, the drift direction Y being orthogonal to the first direction X.

[0080] An ion implanter for injecting ions into the space between the ion mirrors, the ion implanter being positioned near the first end of the ion mirrors; and

[0081] A detector for detecting ions after they have undergone multiple reflections between the ion mirrors, the detector being positioned near the first end of the ion mirror;

[0082] The analyzer can be configured to analyze ions by the following operations:

[0083] (i) Ions are injected from an ion implanter into the space between ion mirrors, wherein the ions complete a first cycle in which the ions follow a zigzag ion path with multiple K reflections between the ion mirrors in the direction X, while: (a) drifting in the drift direction Y toward the second end of the ion mirror, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back in the drift direction Y toward the first end of the ion mirror;

[0084] (ii) Reverse the drift velocity of the ions near the first end of the ion mirror, causing the ions to complete another cycle in which the ions follow a zigzag ion path with multiple K reflections between the ion mirrors in the X direction, while: (a) drifting towards the second end of the ion mirror in the drift direction Y, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back towards the first end of the ion mirror in the drift direction Y;

[0085] (iii) Repeat step (ii) once or more; and subsequently

[0086] (iv) Cause the ions to travel to the detector for detection.

[0087] Alternatively, the analyzer may be an ion mobility analyzer, and the physicochemical property may be ion mobility. Attached Figure Description

[0088] The various implementation schemes will now be described in more detail with reference to the accompanying drawings, in which:

[0089] Figure 1 The analytical instruments according to the implementation scheme are shown schematically;

[0090] Figure 2 A cyclic ion analyzer according to the implementation scheme is schematically shown;

[0091] Figure 3 A closed-loop multi-reflection ion trap mass analyzer according to an embodiment is schematically shown;

[0092] Figure 4 A multi-reflection time-of-flight quality analyzer according to an implementation scheme is schematically shown;

[0093] Figure 5 A multi-reflection time-of-flight quality analyzer according to an implementation scheme is schematically shown;

[0094] Figure 6 A method for disambiguating spectra obtained from a cyclic ion analyzer according to an embodiment is illustrated schematically.

[0095] Figure 7 A method for disambiguating spectra obtained from a cyclic ion analyzer according to an embodiment is illustrated schematically.

[0096] Figure 8 A cyclic ion analyzer according to the implementation scheme is schematically shown;

[0097] Figure 9 This demonstrates how different m / z ions can fall into different numbers of cycles in a cycle analyzer and the resulting convolutional time-of-flight spectra.

[0098] Figure 10A The convolutional time-of-flight spectrum is shown, and Figure 10B The recovered mass spectra are shown using the method according to the implementation scheme;

[0099] Figure 11 A shows the implementation scheme when Figure 4 The measured ion peaks for m / z 524 ions were obtained when the instrument was not operated in zoom mode, and Figure 11 B to Figure 11 D shows when Figure 4 The measured ion peak for the m / z 524 ion was obtained when the instrument was operated in zoom mode;

[0100] Figure 12 The mass spectra of the calibration solution obtained using the scaling mode according to the embodiment are shown; and

[0101] Figure 13 Data from the disambiguation method according to the implementation scheme are shown. Detailed Implementation

[0102] Figure 1An analytical instrument that can be operated according to the implementation scheme is illustrated schematically. The analytical instrument may be a mass spectrometer (which may optionally include an ion mobility separator) or an ion mobility spectrometer. Figure 1 As shown, the analytical instrument includes an ion source 10, one or more ion transfer stages 20, and an analyzer 30.

[0103] Ion source 10 is configured to generate ions from the sample. Ion source 10 can be any suitable continuous or pulsed ion source, such as an electrospray ionization (ESI) ion source, a MALDI ion source, an atmospheric pressure ionization (API) ion source, a plasma ion source, an electron ionization ion source, a chemical ionization ion source, etc. In some embodiments, more than one ion source may be provided and used. The ions can be any suitable type of ion to be analyzed, such as small and large organic molecules, biomolecules, DNA, RNA, proteins, peptides, fragments thereof, etc.

[0104] The ion source 10 may optionally be coupled to a separation device, such as a liquid chromatography separation device or a capillary electrophoresis separation device (not shown), such that the sample ionized in the ion source 10 originates from the separation device.

[0105] Ion transfer stage 20 is disposed downstream of ion source 10 and may include an atmospheric pressure interface and one or more ion directors, lenses, and / or other ion optics configured such that some or all of the ions generated by ion source 10 may be transferred from ion source 10 to analyzer 30. Ion transfer stage 20 may include any suitable number and configuration of ion optics, such as optionally including one or more of the following: one or more RF and / or multipolar ion directors, one or more ion directors for cooling ions, one or more mass-selective ion directors, etc.

[0106] Analyzer 30 is disposed downstream of ion transfer stage 20 and configured to receive ions from ion transfer stage 20. The analyzer is configured to analyze the ions to determine their physicochemical properties, such as their mass-to-charge ratio, mass, ion mobility, and / or collision cross-section (CCS). To this end, analyzer 30 is configured to allow ions to traverse an ion path within analyzer 30 and to measure the time taken for the ions to traverse the ion path (drift time). Therefore, analyzer 30 may include an ion detector disposed at the end of the ion path, wherein the analyzer is configured to record the time it takes for the ions to arrive at the detector. The instrument may be configured to determine the physicochemical properties of the ions based on the measured drift time. The instrument may be configured to generate a spectrum of the analyzed ions, such as a mass spectrometer or an ion mobility spectrum.

[0107] In a particular embodiment, analyzer 30 is a time-of-flight (ToF) mass analyzer, configured, for example, to determine the mass-to-charge ratio (m / z) of ions by causing ions to traverse along an ion path within a drift region of the analyzer, wherein the drift region is maintained at a high vacuum (e.g., <1×10⁻⁶). -5 Ions can be accelerated into the drift region by an electric field and detected by an ion detector positioned at the end of the ion path. Acceleration allows ions with relatively low mass-to-charge ratios to achieve relatively high velocities and arrive at the ion detector before ions with relatively high mass-to-charge ratios. Therefore, the ions arrive at the ion detector after a time determined by the ion velocity and the length of the ion path, making it possible to determine the ion's mass-to-charge ratio. Each ion or group of ions arriving at the detector can be sampled by the detector, and the signal from the detector can be digitized. The processor can then determine values ​​indicating the time of flight and / or mass-to-charge ratio (“m / z”) of the ion or group of ions. Data from multiple ions can be collected and combined to generate time-of-flight (“ToF”) spectra and / or mass spectra.

[0108] In an alternative embodiment, analyzer 30 is an ion mobility analyzer, configured, for example, to determine the ion mobility of ions by causing ions to traverse an ion path within a drift region of the analyzer, wherein a buffer gas is provided in the drift region. Ions can be propelled through the buffer gas by an electric field (or ions can be propelled through the drift region by a gas flow, wherein the electric field is arranged opposite to the gas flow) and can be detected by an ion detector disposed at the end of the ion path. Ions with relatively high mobility will arrive at the ion detector before ions with relatively low mobility. Thus, ions can be separated according to their ion mobility and can arrive at the ion detector after a time determined by the ion mobility of the ions. Each ion or group of ions arriving at the detector can be sampled by the detector, and the signal from the detector can be digitized. The processor can then determine values ​​indicating the drift time and / or ion mobility of the ions or groups of ions. Data from multiple ions can be collected and combined to generate a drift time spectrum and / or an ion mobility spectrum.

[0109] Analyzer 30 may also include an ion mobility separator coupled to the mass analyzer, for example, wherein the mass analyzer is provided at the end of the ion mobility portion of the ion path. In these embodiments, any suitable type of mass analyzer can be provided, such as a time-of-flight mass analyzer, or an electrostatic ion trap mass analyzer, such as an electrostatic orbit trap, and more specifically, an Orbitrap manufactured by Thermo Fisher Scientific. TM FT quality analyzer.

[0110] It should be pointed out that, Figure 1This is merely illustrative, and the analytical instrument may (and indeed in various embodiments) include any number of one or more additional components. For example, in some embodiments, the analytical instrument includes a collision or reaction unit for breaking or reacting ions, and the ions analyzed by the analyzer 30 may be fragment or product ions produced by breaking or reacting the parent ions generated by the ion source 10.

[0111] For example Figure 1 As shown, the instrument is under the control of a control unit 50 (such as a suitably programmed computer), which controls the operation of various components of the instrument, including the analyzer 30. According to the embodiment described herein, the control unit 50 can also receive and process data from various components, including detectors.

[0112] According to various embodiments, analyzer 30 is a circulating analyzer. Therefore, the ion path within analyzer 30 consists of at least a first portion and a second circulating portion, wherein the ion path is configured such that ions traveling along the ion path will traverse the first portion only once and will traverse the second circulating portion once or multiple times (e.g., multiple times) before being detected. This is due to... Figure 2 It is shown schematically.

[0113] like Figure 2 As shown, the analyzer 30 includes an ion path 32 between the ion implanter 31 and the ion detector 33. The ion implanter 31 is configured to implant ions into the ion path 32, whereby the ions travel along the ion path 32 and are detected by the detector 33 located at the end of the ion path 32. Figure 2 As shown, the ion path 32 consists of a first segment 32a, a second loop segment 32b, and a third segment 32c. Ions traveling along the ion path 32 between the ion implanter 31 and the ion detector 33 traverse the first segment 32a only once, then traverse the second loop segment 32b once or multiple times (e.g., multiple times), and then traverse the third segment 32c only once. The ion path 32 may include any number of other segments. The ion path may also include only one of the first segment 32a and the third segment 32c.

[0114] It should be understood that the circulating analyzer advantageously allows for an increase in the length of the ion path 32 within the analyzer 30 (between the injector 31 and the detector 33), thereby improving the resolution of the analyzer 30.

[0115] The circulating analyzer 30 may include any suitable circulating ion analyzer having an ion path 32 configured such that ions can traverse a circulating segment 32b of the ion path multiple times before being detected. Thus, for example, the analyzer 30 may be a circulating time-of-flight (ToF) mass analyzer, a circulating ion mobility analyzer, or a circulating ion mobility separator coupled to a mass analyzer. Figures 3 to 5 Various exemplary implementations of the cycle analyzer 30 are shown.

[0116] Figure 3 Details of a closed multi-reflection ion trap time-of-flight mass analyzer according to a first exemplary embodiment of analyzer 30 are schematically shown.

[0117] like Figure 3 As shown, the analyzer includes a pair of ion mirrors 34 and 35, which face each other and together form an ion trap. Ion mirrors 34 and 35 are configured such that ions trapped in the ion trap will oscillate between ion mirrors 34 and 35 along an infinitely extending (cyclic) ion path 32b until these ions are released. Ions can be introduced into the ion trap from an ion source (injector) 31 and ultimately detected by an ion detector 33. Figure 3 In the illustrated embodiment, ion entry and extraction into the ion trap are controlled by applying a suitable voltage to a deflector 36 arranged in the region between mirrors 34 and 35. Alternatively, ion reception and extraction can be achieved by switching between capture and transmission modes using one or both of ion mirrors 34 and 35.

[0118] exist Figure 3 In the illustrated embodiment, the ion path 32 is configured such that ions (between implanter 31 and deflector 36) traverse a first segment 32a of the ion path once, then (between ion mirrors 34 and 35) traverse a second loop segment 32b of the ion path multiple times, and subsequently (between deflector 36 and detector 33) traverse a third segment 32c of the ion path once.

[0119] In this type of circulating analyzer, ion flight times can be as long as several milliseconds, thus resolutions can typically reach >100,000, or even >500,000. However, space charge within a finite volume can degrade analyzer performance due to strong coalescence effects.

[0120] Figure 4 and Figure 5 Details of another exemplary embodiment of analyzer 30 are schematically illustrated. In these embodiments, analyzer 30 is a multiple reflection time-of-flight (MR-ToF) mass analyzer capable of operating in a so-called multi-pass “scaling” operating mode.

[0121] like Figure 4 and Figure 5 As shown, the multi-reflection time-of-flight analyzer 30 includes a pair of ion mirrors 34 and 35, which are spaced apart in a first direction X and face each other. The ion mirrors 34 and 35 extend along an orthogonal drift direction Y between their first and second ends.

[0122] An ion source (injector) 31, which can be in the form of an ion trap, can be positioned at one end (first end) of the analyzer. The ion source 31 can be arranged and configured to receive ions from the ion transfer stage 20. Ions can be accumulated in the ion source 31 before being implanted into the space between the ion mirrors 34 and 35. Figure 4 and Figure 5 As shown, ions can be injected from ion source 31 at relatively small injection angles or drift velocities, forming Z-shaped ion orbits, in which different oscillations between ion mirrors 34 and 35 are separated in space. Figure 3 Compared to other analyzers, this has the effect of reducing the space charge effect within the analyzer.

[0123] One or more lenses and / or deflectors may be arranged along the ion path between the ion source 31 and the ion mirror 35, which is first encountered by the ions. For example, Figure 4 and Figure 5 As shown, the first out-of-plane lens 37, the injection deflector 38, and the second out-of-plane lens 39 can be arranged along the ion path between the ion source 31 and the ion mirror 35, which is first encountered by the ions. Other arrangements are also possible. Generally, one or more lenses and / or deflectors can be configured to appropriately adjust, focus, and / or deflect the ion beam, i.e., to make the ion beam follow a desired trajectory through the analyzer.

[0124] The analyzer also includes another deflector 36, which is arranged along the ion path between ion mirrors 34 and 35. Figure 4 and Figure 5 As shown, the deflector 36 can be arranged approximately equidistantly along the ion path, between ion mirrors 34 and 35, after the first ion mirror reflection of the ion beam (in ion mirror 35), and before the second ion mirror reflection of the ion beam (in another ion mirror 34).

[0125] The analyzer also includes a detector 33. Detector 33 can be any suitable ion detector, any suitable ion detector being configured to detect ions and, for example, record the intensity and arrival time associated with the arrival of the ions at the detector. Suitable detectors include, for example, one or more conversion multipliers, followed optionally one or more electron multipliers, etc.

[0126] In the analyzer's "normal" operating mode, ions are injected from ion source 31 into the space between ion mirrors 34 and 35 in such a manner that the ions follow a zigzag ion path with multiple reflections between ion mirrors 34 and 35 in direction X, while: (a) drifting from deflector 36 towards the second ends of ion mirrors 34 and 35 along the drift direction Y, (b) reversing the drift velocity near the second ends of ion mirrors 34 and 35, and subsequently (c) drifting back towards deflector 36 along the drift direction Y. This then allows the ions to travel from deflector 36 to detector 33 for detection.

[0127] exist Figure 4 In the analyzer, both ion mirrors 34 and 35 are tilted relative to direction X and / or drift direction Y. Conversely, only one of ion mirrors 34 and 35 can be tilted, and for example, the other ion mirror can be arranged parallel to the drift direction Y. Generally, the ion mirrors are spaced apart from each other in direction X along their length in the drift direction Y. The drift velocity of the ions toward the second end of the ion mirror is relative to the electric field generated by the non-constant distance between the two ion mirrors, and this electric field causes the ions to reverse their drift velocity near the second end of the ion mirror and drift back toward the deflector in the drift direction.

[0128] Figure 4 The analyzer shown also includes a pair of calibration strip electrodes 40. Ions traveling along the drift length are slightly deflected each time they pass through mirrors 34, 35, and the additional strip electrodes 40 are used to correct for time-of-flight errors caused by the varying distance between the mirrors. For example, the strip electrodes 40 can be electrically biased so that the ion oscillation period between the ion mirrors is substantially constant along the entire drift length (although there is a non-constant distance between the two mirrors). The ions eventually find themselves reflected back along the drift space and focused at detector 33.

[0129] As given in U.S. Patent No. 9,136,101 Figure 4 Further details of the tilting mirror type multi-reflection time-of-flight mass analyzer are contained herein by reference.

[0130] exist Figure 5 In the analyzer, ion mirrors 34 and 35 are parallel to each other. In this embodiment, in order to cause ions to reverse their drift velocity near the second end of the ion mirror and drift back towards the deflector along the drift direction, the analyzer includes a second deflector 41 located at the second end of the ion mirrors 34 and 35.

[0131] For example Figure 5As shown, in this embodiment, a lens may be included in the injection deflector 38 and / or deflector 36. This allows the ion beam to extend a short distance into the analyzer before encountering a long-focal-length lens that has the effect of focusing the ion beam along its length. The lens may be an elliptical drift focusing (converging) lens mounted within deflector 36. A second deflector 41 may also be included to reverse the ion beam direction while maintaining control over the focal length property.

[0132] It is given in British Patent No. GB ​​2,580,089 Figure 5 Further details of the single-lens multi-reflection time-of-flight quality analyzer described in the British Patent are incorporated herein by reference.

[0133] exist Figure 4 and Figure 5 In the analyzer shown, the ion beam is allowed to extend relatively broadly over most of its flight path (in the drift direction Y). This differs from, for example, multiple reflection time-of-flight (MR-ToF) mass analyzers, which use a set of periodic lenses to focus the ion beam across its entire flight path, as described, for example, in the article by A. Verenchikov et al. in the Journal of Applied Solution Chemistry and Modeling, 2017, Vol. 6, pp. 1–22. A significant advantage of allowing the ion beam to extend broadly over most of its flight path is the reduction of space charge effects, which can be a significant problem for time-of-flight analyzers. However, the implementation described herein is also applicable to other MR-ToF analyzer designs, such as the Verenchikov-type MR-ToF analyzer.

[0134] exist Figure 4 and Figure 5 In the illustrated embodiment, the fact that the ion beam is relatively wide in the drift dimension Y means that deflector 36 should be able to accept this wide beam without introducing clipping or non-uniform deflection. A suitable deflector design is a trapezoidal or prismatic deflector. Therefore, deflector 36 may include a trapezoidal or prismatic electrode arranged above the ion beam and another trapezoidal or prismatic electrode arranged below the ion beam. The electrodes may be angled relative to the ion beam. Ions may experience a relatively strong electric field at the edges of the angled electrodes, inducing deflection. The electrodes may be positioned outside the plane of deflection, allowing them to be easily made wide enough to accept a wide ion beam (at least compared to more conventional deflector plates that would be located on either side of the ion beam).

[0135] In the implementation, the multiple reflection time-of-flight (MR-ToF) mass analyzer operates in a multi-pass "scaling" (cyclic) operating mode. This causes the ions to cycle multiple times within the analyzer along the drift direction Y. Increasing the number of cycles N increases the length of the ion path within the analyzer (between the injector and detector), thereby improving the analyzer's resolution. In the Verenchikov analyzer, this is achieved by controlling the voltage on the incident lens. For Figure 4 and Figure 5 The analyzer shown typically uses a deflector 36 located at the front of the analyzer to reduce the injection angle and / or optimize the number of oscillations (K) within a single drift pass. It can also be used to reverse the drift direction and velocity of the ions, allowing the ions to complete an additional cycle through the analyzer.

[0136] Therefore, in the multi-cross "scaling" (cycle) operation mode, ions complete multiple (N) cycles within the analyzer, wherein in each cycle, ions drift in the drift direction Y from the deflector 36 (or entrance lens) toward the opposite (second) ends of ion mirrors 34, 35, and subsequently return to the deflector 36 (or entrance lens). In each cycle, ions also undergo multiple (K) reflections in the X direction between the ion mirrors. Thus, in each cycle, ions adopt a zigzag ion path 32b through the space between ion mirrors 34, 35.

[0137] exist Figure 4 and Figure 5 In the analyzer shown, an initial cycle can be initiated by injecting ions from implanter 31 into the space between ion mirrors 34 and 35. Ions can be reflected in one of the ion mirrors 35 and then travel to deflector 36. No voltage may be applied to deflector 36 (or an appropriate (e.g., relatively small) voltage may be applied to deflector 36) such that ions leave deflector 36 in a direction toward the second end of the ion mirror. With deflector 36 present, ions follow a zigzag ion path 32b with multiple (K) reflections in direction X between ion mirrors 34 and 35, while: (a) drifting from deflector 36 toward the second end of the ion mirror along drift direction Y, (b) reversing the drift velocity near the second end of the ion mirror, and (c) drifting back toward deflector 36 along drift direction Y.

[0138] After the ions have completed the initial cycle, each subsequent cycle is initiated by reversing the drift direction velocity of the ions (near the first end of the ion mirror) using deflector 36. To do this, an appropriate voltage can be applied to deflector 36, causing the ions to leave deflector 36 with a drift direction velocity opposite to the initial drift direction velocity of the ions entering deflector 36.

[0139] After the ions have completed the desired number (N) cycles within the analyzer, they are allowed to travel from deflector 36 to detector 33 for detection. For this purpose, the voltage can be removed from deflector 36 (or an appropriate voltage can be applied to the deflector), causing the ions to exit deflector 36 in a direction toward detector 33. The ions may be reflected in one (or the other) of the ion mirrors 34 before traveling to (and being detected by) detector 33.

[0140] exist Figure 4 and Figure 5 In the illustrated embodiment, the ion path is configured such that ions (between implanter 31 and deflector 36 via ion mirror 35) traverse a first segment 32a of the ion path once, then (between deflector 36 via the opposite (second) ends of ion mirrors 34, 35) traverse a second loop segment 32b of the ion path multiple times, and subsequently (between deflector 36 and detector 33 via another ion mirror 34) traverse a third segment 32c of the ion path once.

[0141] although Figures 3 to 5 An exemplary embodiment of the circulating analyzer 30 is shown, but it should be understood that various alternative embodiments are possible. For example, the analyzer 30 may alternatively be a circulating ion mobility analyzer or a circulating ion mobility separator coupled to a mass analyzer.

[0142] In these embodiments, the circulating ion mobility analyzer or circulating ion mobility separator may include a closed-loop ion separator, such as the type described in UK patent application number GB 2,562,690. Ions can be separated within a fixed integer number of cycles around the ion mobility separator according to their ion mobility. A gate may be provided that can be closed to allow multi-pass operation. The gate may be opened to allow ions to leave the ion mobility separator after they have formed one or more loops within the ion mobility separator. Using a circulating ion mobility separator allows for a higher degree of separation and therefore allows for higher ion mobility resolution.

[0143] In these embodiments, the ion path can be configured such that ions traverse a first segment of the ion path once (before the closed-loop ion separator), then traverse a second loop segment of the ion path multiple times (within the closed-loop ion separator), and subsequently traverse a third segment of the ion path once (after the closed-loop ion separator).

[0144] The common benefit among various types of cyclic analyzers (in which ions are repeatedly cycled N times along the ion path within the analyzer) is that increasing the number of cycles N increases the length of the ion path within the analyzer, thereby improving the analyzer's resolution.

[0145] However, a common problem is that in multiple cycles N through the analyzer, faster-moving (e.g., lighter) ions can catch up with (e.g., overlap) slower-moving (e.g., heavier) ions. This complicates the resulting spectrum and can make it difficult to accurately determine the desired physicochemical properties (e.g., m / z or ion mobility) of all detected ions, because the number of cycles N taken for each ion peak in the spectrum becomes ambiguous.

[0146] Therefore, the implementation scheme provides a method for disambiguating the spectrum generated by the cyclic ion analyzer. By comparing two sets of ion data obtained under different analyzer settings, the number of times N that ions contributing to the ion peak traverse the cyclic segment 32b of the ion path 32 can be determined, thereby allowing the physicochemical properties of those ions to be unambiguously determined and assigned to the ion peak.

[0147] Although according to Figure 4 and Figure 5 The following discussion describes the MR-ToF analyzer, but those skilled in the art will understand that similar considerations can be applied to various other types of cyclic analyzers, such as cyclic ToF analyzers and cyclic ion mobility separators.

[0148] Figure 4 and Figure 5 The ion pathways depicted are formed, for example, by all ions with mass-to-charge ratios ranging from (m / z)1 to (m / z)2. Deflector 36 will switch from mode 1 (deflection from source 31 to the loop) to mode 2 (deflection from the loop back to the loop) and finally to mode 3 (deflection from the loop to detector 33). The switching times will be expressed as t0. 12 and t 23 Assume that time zero is the injection moment.

[0149] The first switch between Mode 1 and Mode 2 should not occur before the first crossing of deflector 36 by the heaviest ion (m / z) 2, and not later than the occurrence of a0+K oscillations by the lightest ion (m / z) 1, where K is the number of oscillations per loop (between subsequent crossings of deflector 36), and a0 represents a portion of the oscillations prior to the first crossing between ion source 31 and deflector 36. Otherwise, the lightest ion will not be correctly set to the next loop. This gives the following double inequality:

[0150] a0 T2≤t 12 ≤(a0 + K) T1 (a)

[0151] Where T1 and T2 are the oscillation times of the lightest and heaviest ions, respectively. Figure 4 and Figure 5 In the implementation plan, a0≈1 / 2.

[0152] The second switch from Mode 2 to Mode 3 should occur no earlier than the heaviest ion undergoing a0 + (N-1)K oscillations, where N is the desired number of loops. Otherwise, the heaviest ion will leave the loop before all loops are formed. On the other hand, the second switch should occur no later than the lightest ion undergoing a0 + NK oscillations; otherwise, the ion will remain in the analyzer for the next undesirable loop. This double inequality reads as follows:

[0153] (a0+NK-K)T2≤t 23 ≤(a0+NK)T1 (b)

[0154] Inequalities (a) and (b) both set upper limits on the ratio of T2 to T1, under which there exists a pair of t 12 and t 23 Furthermore, for any N>1, the upper bound from (b) is stronger (lower) than the upper bound from (a):

[0155]

[0156] Since the flight time is proportional to the square root of m / z, this inequality directly translates to the maximum unambiguous mass range (UMR):

[0157]

[0158] To achieve full UMR, the switching time t 23 Must be:

[0159] t 23 =(a0+NK)T1=(a0+NK-K)T2

[0160] The first switching time allows for some degree of freedom in its definition. We can assume, for example, that its minimum possible value t can be used. 12 =a0 T2, which allows for electron ripple before the lightest ion reaches the deflector next time.

[0161] Table 1 shows a simulation of a mass analyzer with an effective oscillation distance of 1.25 m and 20 oscillations per loop. Resolution was calculated based on the peak half-width at half-maximum (HWHM). The collapse in the m / z range becomes quite significant as the number of loops increases.

[0162] No scaling 1.7 125 Restricted source >15x 2x 6.5 65 3.9x 3x 2.2 280 2.23x 4x 7.0 120 1.77x 5x 3.0 340 1.56x

[0163] Table 1

[0164] For example, the m / z range of ions entering analyzer 30 can be limited by using switchable deflectors, mass filters (e.g., quadrupole mass filters), or other methods to approximately match the UMR of the scaling method and thus eliminate ambiguity in the m / z assignment. However, this is quite wasteful for ion transport, and a more efficient method to maintain sensitivity may be preferred.

[0165] Therefore, disambiguation of the complex spectrum according to the implementation scheme is generally preferred, thereby assigning the correct number of drift reflections to each ion peak and determining the accurate m / z of each ion peak accordingly.

[0166] One possible method for disambiguation would be to directly assign the correct number of cycles N to each ion peak based on its resolution. This initially appears to be a fairly attractive method based on the resolution shifts observed in Table 1. Similarly, m / z correlation properties (such as the response of a single ion detector, the interval between different charge states, isotopic or common fragmentation paths, such as loss of ammonia or water, etc.) can be used to pre-assign approximate m / z to each ion peak, and thus pre-assign the number of cycles. This is also possible compared to survey scans in non-scaling mode, especially for MR-ToF analyzers with drift separation, where even survey scans are very high resolution and of high quality. However, in practice, these methods become very complex due to the space charge effect of strong ion peaks and statistical problems with small ion peaks.

[0167] According to the implementation plan, the disambiguation of the cyclic analyzer spectrum (such as the ToF mass analyzer spectrum or the ion mobility analyzer spectrum) is accomplished by changing the flight time on the ion path segments that include (32b) or do not include (32a, 32c) in the repetitive loop.

[0168] As used in this article, the "effective ion path" is defined as the time of flight multiplied by the ion velocity at the nominal accelerating voltage. The effective ion path can be altered by directly changing the ion path length or by changing the voltage that alters the time of flight.

[0169] See you again Figure 2 The effective ion path along the entire ion trajectory 32 consists of three parts:

[0170] L = L0 + L m N+L1

[0171] Where L0 and L1 correspond to the non-repeating segments 32a and 32c outside the loop (e.g., in...) Figures 3 to 5 In the diagram, paths 32a and 32c correspond to the path between injector 31 and switchable deflector 36, respectively, and the path from deflector 36 to ion detector 33. Path L mIt is the effective length of a 32b segment that is repeated N times in the loop.

[0172] When the effective ion paths L0 and L are modified proportionally... m With L1, the measured time of flight will change proportionally for each ion, regardless of how many loops N that ion produces. However, with L... m Change ΔL m Meanwhile, keeping L0+L1 constant, the flight time is modified by Δt in the following proportion:

[0173]

[0174] This can be decomposed into:

[0175]

[0176] The sum L0+L1 changes and ΔL0 and L m Under the other unchanged conditions, the relative flight time offset is:

[0177]

[0178] This leads to another formula for N:

[0179]

[0180] Therefore, in both cases, the number of cycles N can be determined based on the measurement time offset Δt of the ion peak detected at time t after implantation. With the number of oscillations N known, the time of flight t can be converted to mass-to-charge ratio (or ion mobility) using a normal conversion.

[0181] Therefore, in the implementation scheme, a first set of ion data is obtained when the analyzer is operated in a first operating mode, and a second set of ion data is obtained when the analyzer is operated in a second, different operating mode. The first and second sets of ion data can be obtained by analyzing ions originating from the same sample (e.g., by analyzing ions generated from adjacent regions of the sample, and / or by analyzing ions generated from the sample at close (adjacent) time points), for example, such that ion peaks corresponding to some, most, or all (a large number of) ion peaks in the first set of ion data appear in the second set of ion data.

[0182] The first and second operating modes differ in at least one parameter of the analyzer 30. Specifically, the ion path 32 of the analyzer is divided into two regions: one region has a flight path 32b affected by the number of traversals N, and at least one region 32a, 32c is unaffected. A parameter change is applied between the two operating modes to disproportionately alter the drift time between one segment and the other. Therefore, the proportional change in drift time depends on how many traversals N the ion undergoes through the loop segment 32b. In an embodiment, the effective ion path L in the loop... m The effective ion pathway L0+L1 outside the loop changes between the two operating modes.

[0183] The effective ion path can be changed by directly altering the ion path length or by changing the voltage that alters the time of flight. Therefore, in the first operating mode, (i) a first potential is provided along the first segments 32a, 32c of the ion path, (ii) a second potential is provided along the loop segment 32b of the ion path, (iii) the first segments 32a, 32c of the ion path have a first path length, and (iv) the loop segment 32b of the ion path has a second path length. In the second operating mode, at least one of the following is changed relative to the first operating mode: (i) the first potential, (ii) the second potential, (iii) the first path length, and (iv) the second path length; for example, such that the effective ion path L in the loop is changed. m The effective ion pathway L0+L1 outside the loop changes relative to the first operating mode.

[0184] This parameter variation will cause a time shift Δt for each ion peak between the two sets of ion datasets. Therefore, the first set of ion data is compared with the second set to identify corresponding (matched) ion peaks. For each identified ion peak pair of interest, the time shift Δt for that ion peak pair between the two datasets is measured. The number of loops N for each peak is then estimated based on the measured time shift Δt (e.g., using the equation above), and N is used to calculate the mass-to-charge ratio (or other physiological and chemical properties) of the ion corresponding to the ion peak.

[0185] The following describes methods for altering the effective ion pathway L in the loop. m Various exemplary implementations of the effective ion path L0+L1 outside the loop. However, it should be understood that various alternatives are possible, for example, depending on the specific design of the cyclic ion analyzer 30.

[0186] In a first exemplary embodiment, the path length of the cyclic segment 32b of the ion path changes between a first operating mode and a second operating mode.

[0187] exist Figure 4 and Figure 5 In a multiple reflection analyzer, the effective length of the loop can be altered by changing the number of reflections K of ions per cycle between ion mirrors 34 and 35, i.e., by changing the number of reflections K of ions in the X direction, while these ions (a) drift along the drift direction Y from deflector 36 toward the second end of the ion mirror, (b) reverse the drift velocity near the second end of the ion mirror, and (c) drift back along the drift direction Y toward deflector 36. This can be accomplished by appropriately varying the voltage applied to deflector 36 between the two operating modes, i.e., causing the ions to exit deflector 36 at slightly different angles between the two operating modes. A suitable voltage offset is approximately several volts or tens of volts. Figure 4 In the case of a tilting mirror type analyzer, the change of K can also be accomplished, or alternatively, by adjusting the voltage applied to the strip electrode 40.

[0188] In the implementation, the number of reflections K between ion mirrors 34 and 35 is varied by ±1 between the two operating modes, and the corresponding time offset Δt is measured for each ion peak. Since the number of crossovers N is low (typically less than 6), the time offset Δt can be measured with moderate precision, and the exact number of loops N can be determined by rounding (eq.Na) to the nearest integer.

[0189] Effective length L of the loop m Proportional to K, this results in a relative change ΔL as the number of oscillations K increases by 1. m / L m = 1 / K. In this case, the formula (eq.Na) is as follows:

[0190]

[0191] Where a0 is the fraction of the oscillation between the injection and the first pass through the switchable deflector 36, and a1 is the fraction of the oscillation after leaving the loop and before impacting the detector 33. Figure 4 and Figure 5 In the analyzer shown, these portions are approximately 0.5 and 0.45, respectively.

[0192] Table 2 shows an example of this disambiguation algorithm applied to the ToF spectra of the Flexmix calibration mixture. Low m / z ions are set to arrive at the detector after N = 2 loops, each containing K1 = 21 oscillations. The corresponding times of flight appear in the first column. However, some ions with higher m / z (mainly Ultramark ions) form another loop due to their lower propagation speed, N = 3. To assign the correct number of loops to each peak, the system is switched to a mode with K2 = 22 oscillations in each loop, and the corresponding times of flight for each of these peaks are detected. These are given in the second column. The value of N* is estimated from the time-of-flight difference using the formula (eq.N.dk), and these values ​​are rounded to the nearest integer. Finally, the m / z ratio is calculated using the following formula:

[0193]

[0194] Where U0 is the accelerating voltage and c N <<1 is the calibration factor, which is defined by prior experiments for each loop number N=2 and 3.

[0195]

[0196] Table 2

[0197] In the implementation, the fractional part of N* comes from the limited calibration accuracy. However, the assignment of the integer N as the rounded value N* is unambiguous. The fewer loops that need to be distinguished from each other, the more reliable the disambiguation process becomes.

[0198] Figure 4 or Figure 5 The advantage of the aforementioned "scaling" mode in the analyzer is that the analyzer has a relatively long flight length L per loop. m (tens of meters) and a relatively small number of loops (N = 1…5). For example, a 15x m / z range provided by ion source 10, where the scaling mode is configured to give two drift passes for the highest m / z ion (N = 2), means that the lowest m / z ion will make four passes (N = 4), making the ambiguity only in whether the ion is making N = 2, 3 or 4 passes.

[0199] Figure 6 This is a flowchart illustrating the disambiguation method according to these implementation schemes. For example... Figure 6As shown, in this method, a first mass spectrum and a second mass spectrum are acquired using an analyzer that operates with different numbers of ion oscillations (K and K+1) in each cycle of the analyzer (step 60). Then, corresponding pairs of ion peaks in the two spectra are identified (step 61), and the number of traversals N of the ion path segment associated with each pair of corresponding ion peaks is estimated (step 62). Finally, N is used to calculate the true m / z of the ions (step 63).

[0200] Another method for determining the number of loops based on the flight time at different oscillation numbers K for each loop is to calculate a list of possible mass-to-charge ratios for each ion peak under different assumptions about the possible number of loops N (from eq.mz). This gives several possible values. Where N is the candidate round

[0201] The number of paths and K = K1, K2. Only for the correct value of N, and The candidate values ​​are (approximately) equal (e.g., within narrow tolerances, such as 10 ppm), while incorrect assumptions about N lead to fundamentally different values.

[0202] As shown in Tables 3A and 3B, for different values ​​of K, only one candidate N (correspondingly 3 and 2) gives a close candidate for m / z. These candidate values ​​are assumed to be correct, and all other m / z calculated using other assumptions about the number of loops are discarded as incorrect values.

[0203]

[0204] Table 3A

[0205]

[0206] Table 3B

[0207] Table 3

[0208] Figure 7 This is a flowchart illustrating the disambiguation method according to these implementation schemes. For example... Figure 7As shown, in this method, a first mass spectrum and a second mass spectrum are acquired using an analyzer that operates with different numbers of ion oscillations (K and K+1) in each cycle of the analyzer (step 70). Corresponding ion peak pairs are identified (step 71). For each candidate value of N (step 72), a candidate m / z value is calculated for each peak (step 73). Thus, a list of possible m / z values ​​for each ion peak of interest is generated. Matching ion peak pairs between the two spectra are then identified to determine the accurate N for each pair of corresponding ion peaks (step 74). Finally, the unambiguous m / z for each matching ion peak pair is determined and assigned to each ion peak (step 75).

[0209] In some implementations, it may be advantageous to use more than two K values ​​at the expense of overall acquisition speed, because some peaks may disappear due to the shift of K, for example, because ions are present within deflector 36 during voltage switching. The disappearance of ion peaks in the spectrum can also, or alternatively, be used to provide information for disambiguation, since the m / z value of the disappearance can be calculated based on deflector size, switching speed / time, etc.

[0210] Generally, the implementation may include analyzing ions in a third operating mode (by determining the drift time of ions along the ion path) to obtain a third set of ion data, wherein in the third operating mode, at least one of (i) a first potential, (ii) a second potential, (iii) a first path length, and (iv) a second path length is changed relative to the first operating mode and / or the second operating mode; comparing the third set of ion data with the first set of ion data and / or the second set of ion data, and determining, based on the comparison, the number of traversals N of the second portion of the ion path performed by the ion associated with the corresponding ion peak.

[0211] In a second exemplary embodiment, disambiguation is performed by comparing the time of flight between two spectra, wherein the non-reflective segment of the flight path has been altered by changing the potential of the non-reflective segment of the flight path.

[0212] Figure 8 A simplified (e.g., MR-ToF) analyzer layout is schematically shown, incorporating a short section of flight tube 80 prior to detector 33. Flight tube 80 can be directly integrated into the detector assembly, for example, as part of a so-called post-accelerator, which includes means configured to accelerate ions to appropriately biased electrodes on a conversion multiplier. Flight tube 80 allows for a change in potential to shift the time-of-flight of ions in the non-reflective segment of the ion path 32c prior to detector 33. Figure 8 It also shows that the ion flight path 32 is separated into several parts, with L0 injected and the reflective part L... m and utilizing the combined flight tube Lt Extracted to detector L1.

[0213] The flight time offset caused by the voltage v applied to the flight tube 70 and The m / z value is proportional and independent of the number of cycles N. Measuring time-of-flight spectra with two (or more) values ​​of v allows for independent evaluation of m / z. Therefore, the number of cycles N can be assigned to each peak. The accurate value of m / z can then be determined based on the cyclic time-of-flight spectrum and the number of cycles assigned to each ion peak of interest.

[0214] exist Figure 8 In the schematic diagram, the ion with a mass-to-charge ratio μ = m / z arrives at the second mirror at the following times:

[0215]

[0216] Where ε0 is the accelerating voltage, and L0 and L m This is the effective length. Let the second mirror abruptly switch from reflection mode to transmission mode at time T2. The number of reflections completed in the second mirror before T2 is:

[0217]

[0218] double parentheses Represents the integer part. The time for ion detection is:

[0219]

[0220] As the number of iterations N gradually decreases with the mass-to-charge ratio μ, the function t D (μ) is non-monotonic. This means that the ToF spectrum t D (μ) is fuzzy and located at t D The peak at that point can correspond to multiple different mass-to-charge ratios μ.

[0221] The μ interval corresponding to a specific integer N(μ) is called the unambiguous quality interval. For N cycles, the corresponding unambiguous interval ranges from M... N+1 To M N ,in:

[0222]

[0223] The corresponding unambiguous quality range is:

[0224]

[0225] Consider a length L t The short flight tube 80 is located between the second mirror and the detector 33 and is biased with a voltage v << ε0. When the voltage is applied, the peak shifts:

[0226]

[0227] As v << ε0, the peak width does not broaden significantly, and the centroid shift is measurable. This allows for a rough estimate of the reverse ion velocity and mass-to-charge ratio μ:

[0228]

[0229] The accuracy is low, but sufficient to determine the number of cycles N for a specific peak. Therefore, the estimated μ* is substituted into the formula (equation Nμ)N(μ*)=[[N*]], where:

[0230]

[0231] Then the exact μ was determined as:

[0232]

[0233] N* is rounded.

[0234] Therefore, in these embodiments, a first set of ion data is obtained when the analyzer is operated in a first operating mode, and a second set of ion data is obtained when the analyzer is operated in a second operating mode, wherein in the second operating mode, the potential of the first (and / or third) segments 32a, 32c along the ion path changes relative to the first operating mode. This change causes a time shift Δt for each ion peak between the two sets of ion data, which is used to estimate the number of cycles N for each peak, and thus to estimate the mass-to-charge ratio (or other physiological and chemical properties), for example, in the manner described above.

[0235] exist Figure 8 In the illustrated embodiment, the flight tube 80 may be positioned in the ion path 32a between the source 31 and the first mirror.

[0236] Another implementation involves altering the acceleration field provided by the ion implanter 31 to accelerate ions along the ion path. In the case where the ion implanter is an ion trap, this may include altering the extraction field provided within the ion trap to accelerate ions from the ion trap along the ion path (e.g., in this implementation, at least a portion of the first segment 32a of the ion path may be considered to be within the ion trap). A suitable extraction field is approximately several hundred V / mm, and a suitable extraction field offset between the first and second operating modes is approximately tens of V / mm.

[0237] It should also be noted that if the voltage applied to flight tube 80 is relatively small, then except for the area located at M N Outside of the nearby ion peaks, the vast majority of ion peaks will remain at the cycle number N.

[0238] These implementations can also be carried out directly in cyclic ion mobility spectrometry (which measures the flight time through a gas-filled drift path). For example, UK patent application GB 2,562,690 describes an instrument combining a cyclic ion mobility analyzer and a short linear drift tube that can be directly adapted to shift the total drift time in a manner similar to that described above.

[0239] Although the exemplary embodiments described above have been described with respect to (between the first and second operating modes) (i) the change in the potential of the non-circulating segments 32a, 32c along the ion path or (ii) the change in the path length of the circulating segment 32b of the ion path, it should be understood that alternatively, (iii) the change in the potential of the circulating segment 32b along the ion path (e.g., by including a flight tube along the circulating segment 32b of the ion path), or (iv) the change in the path length of the non-circulating segments 32a, 32c of the ion path (e.g., by controlling the number of reflections of the K ion between the two ion mirrors), i.e., making the loop L m One of the effective ion paths in the circuit and the effective ion paths outside the loop L0+L1 changes relative to the first operating mode.

[0240] right Figure 8 The numerical example of the arrangement shown is used for modeling, where L m =0.5m, L0 and L1 = 0.4m, L t =0.3m, T2 =0.5ms and ε0 =1000eV. A voltage offset of 10V is applied to the flight tube 80 between the two spectra. The flight time of ions with a mass-to-charge ratio ranging from 250 to 3250 is calculated in steps of 150m / z.

[0241] Figure 9 The diagram shows how ions with different m / z ratios (top) fall into different numbers of reflections, and the resulting convolution time-of-flight spectra (left).

[0242] Figure 10A The diagram shows the time-of-flight spectra of two overlapping convolutions, illustrating the effect of applying L... t The small shift between peaks generated by the 10V shift in the region, and Figure 10B The recovered mass spectra are shown, obtained by measuring the shifts between peaks and assigning the number of cycles. This information is also reproduced in Table 4.

[0243]

[0244]

[0245] Table 4

[0246] This example assumes that matching peaks before and after the shift is not difficult, which may be reasonable for small shifts and uncongested spectra. In more complex cases, as described above with respect to the first exemplary disambiguation method, it may be beneficial to have precise calibration of both the shifted and unshifted spectra and to assign multiple possible m / z values ​​to each ion peak, and then match the peaks together.

[0247] Constructed a combination Figure 4 The analyzer is designed for mass spectrometry. Analyte ions (m / z 524) generated by an electrospray source are separated by a quadrupole, accumulated and cooled in an extraction ion trap, and then injected into the analyzer through a 330V / mm pulsed field, under which these ions are rapidly accelerated to a flight energy of 4KV.

[0248] Ion dispersion is controlled by a pair of lenses, and the ion orientation is set by a first prism deflector 38, allowing ions to pass through a second prism deflector 36 via reflection from the ion mirror 35. The second prism deflector 36 is set to -160V to allow ions to enter the analyzer. After approximately 200 μs, the prism deflector is switched to a +280V capture mode and held in this mode for 800 μs, sufficient for the ions to undergo a second drift pass. The prism 37 is then switched back to the -160V transmission mode, and the captured ions are extracted to the electron multiplier detector 33.

[0249] Figure 11 The m / z 524 peak is shown when the instrument is operated in single-pass mode and zoom mode. A much higher resolution is observed in 3x zoom mode without significant signal loss, although a greater number of drift passes are observed to more significantly reduce transmission.

[0250] Figure 12 Scaling-mode mass spectra of the infused Pierce Flexmix calibration solution (a common calibration mixture containing MRFA and Ultramark) are shown. In this example, the ion mass range delivered to the ToF analyzer is first separated by a resolvable quadrupole to remove obscuring peaks. A range of approximately 1.6 x m / z is observed from the first mass of 390.

[0251] Figure 13 Data from tests performed according to a first exemplary embodiment of the disambiguation method are shown. Flexmix ions were injected into the trap with an m / z isolation window 390–2000 that was much wider than the unambiguous m / z window 390–625, resulting in high m / z overlabeled ions with a -1 drift cross appearing in the mass spectrum. The number of oscillations K for each drift cross was then reduced by 1, and the mass calibration coefficient was recalculated. High m / z overlabeled peaks were observed to be shifted by -620 ppm in m / z, thus readily allowing their identification.

[0252] A similar experiment according to the second exemplary embodiment was performed by changing the pulse extraction field of the ion implanter from 330 to 240 V / mm, which resulted in a high m / z ion offset of -40 ppm.

[0253] As will be understood from the above, the implementation provides a method for operating an analytical instrument (e.g., a time-of-flight mass spectrometer) comprising an analyzer configured to determine the time of flight of ions along a path including a circulating segment and a non-circulating segment. The circulating segment is configured such that at least some ions form more than one loop therein, and the non-circulating segment is configured such that all ions traverse it only once. For example, at least one of the circulating and non-circulating segments can be controlled using at least one electrode having a switchable voltage, which, when switched, modifies the time of flight of ions in that segment.

[0254] The method may include determining a first set of flight times for ions upon completion of a cyclic and non-cyclic segment, changing the voltage on at least one of the control electrodes, and then determining a second set of flight times for ions upon completion of both the cyclic and non-cyclic segments. The method may include determining the number of loops in the cyclic segment performed by the ion of interest based on the flight time difference between the first and second set of flight times. The method may then include determining the mass-to-charge ratio of at least one ion based on the complete flight path including the determined number of loops in the cyclic segment.

[0255] The cyclic or non-cyclic segment can be voltage-controlled, with the voltage, when applied, modifying the ion velocity in at least a portion of the path, which in turn modifies the flight time in the cyclic or non-cyclic segment. The cyclic segment can be controlled by varying the voltage that controls the ion flight length within that segment. Ions can oscillate more than once within a single loop in the cyclic segment, and the number of such oscillations can be controlled by applying a control voltage.

[0256] The relative difference in flight times between the first and second groups can be largely determined by the number of loops in the ion orbitals within the cyclic segment, and the number of loops can be estimated from the difference of at least one ion. The mass-to-charge ratio can be estimated for a set of candidate numbers of loops, and the true number of loops can be determined by comparing the estimated mass-to-charge ratios for the first and second groups of flight times.

[0257] Although the invention has been described with reference to various embodiments, it should be understood that various changes may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A method of operating an analytical instrument, the analytical instrument comprising an ion analyzer, the ion analyzer being configured to analyze ions by determining the drift time of ions along an ion path, the ion path comprising at least a first segment and a circulation segment, wherein the ion path is configured such that ions traverse the first segment once and traverse the circulation segment once or multiple times; the method comprising: The analyzer is operated in a first operating mode, wherein in the first operating mode: (i) a first potential is provided along a first segment of the ion path, (ii) a second potential is provided along a loop segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the loop segment of the ion path has a second path length, and ions are analyzed by determining the drift time of ions along the ion path in order to obtain a first set of ion data; The analyzer is operated in a second operating mode by changing at least one of (i) the first potential, (ii) the second potential, (iii) the first path length and (iv) the second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a second set of ion data. The first set of ion data is compared with the second set of ion data, and the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data is identified. The number of times the cyclic segment of the ion path traversed by the ion associated with the corresponding first and second ion peaks is determined. N ;as well as Use the determined number of traversals N To determine the values ​​of the physicochemical properties of the ions associated with the corresponding first and second ion peaks. The ion analyzer is a time-of-flight (ToF) mass analyzer, and the physicochemical property is the mass-to-charge ratio (m / z). The time-of-flight (ToF) quality analyzer is a multiple reflection time-of-flight (MR-ToF) quality analyzer, which includes: Two ion mirrors are spaced apart and opposite to each other in a first direction X. Each mirror typically extends along a drift direction Y between a first end and a second end, the drift direction Y being orthogonal to the first direction X. An ion implanter for injecting ions into the space between the ion mirrors, the ion implanter being positioned near the first end of the ion mirrors; and A detector for detecting ions after they have undergone multiple reflections between the ion mirrors.

2. The method of claim 1, wherein the detector is positioned near the first end of the ion mirror, and the analyzer is configured to analyze ions by: (i) Ions are injected from the ion implanter into the space between the ion mirrors, wherein the ions complete a first cycle, in which the ions follow a plurality of paths along the first direction X between the ion mirrors. K The reflected Z-shaped ion path simultaneously: (a) drifts along the drift direction Y toward the second end of the ion mirror, (b) reverses the drift direction velocity near the second end of the ion mirror, and (c) drifts back along the drift direction Y toward the first end of the ion mirror. (ii) Reversing the drift direction velocity of the ions near the first end of the ion mirror, causing the ions to complete another cycle in which the ions travel along the first direction X between the ion mirrors. K The reflected Z-shaped ion path simultaneously: (a) drifts along the drift direction Y toward the second end of the ion mirror, (b) reverses the drift direction velocity near the second end of the ion mirror, and (c) drifts back along the drift direction Y toward the first end of the ion mirror. (iii) Repeat step (ii) once or more; and subsequently (iv) Cause the ions to travel to the detector for detection.

3. The method according to claim 2, wherein the multiple reflection time-of-flight (MR-ToF) mass analyzer further comprises: A deflector, the deflector being positioned near the first end of the ion mirror; and The analyzer is configured to analyze ions by: (i) Ions are injected from the ion implanter into the space between the ion mirrors, wherein the ions complete a first cycle, in which the ions follow a plurality of paths along the first direction X between the ion mirrors. K The reflected zigzag ion path simultaneously: (a) drifts from the deflector toward the second end of the ion mirror along the drift direction Y, (b) reverses the drift direction velocity near the second end of the ion mirror, and (c) drifts back toward the deflector along the drift direction Y. (ii) Using the deflector to reverse the drift direction velocity of the ions, causing the ions to complete another cycle in which the ions follow a plurality of paths along the first direction X between the ion mirrors. K The reflected zigzag ion path simultaneously: (a) drifts from the deflector toward the second end of the ion mirror along the drift direction Y, (b) reverses the drift direction velocity near the second end of the ion mirror, and (c) drifts back toward the deflector along the drift direction Y. (iii) Repeat step (ii) once or more; and subsequently (iv) Cause the ions to travel from the deflector to the detector for detection.

4. The method of claim 3, wherein the method includes changing the second path length in the second operating mode by changing the number K of reflections K of ions along the zigzag ion path between the ion mirrors.

5. The method of claim 4, wherein the number K of reflections K of ions between the ion mirrors as they follow the zigzag ion path is changed by varying the voltage applied to the deflector.

6. The method of claim 3, 4 or 5, wherein the ion mirrors are spaced apart from each other by a non-constant distance along at least a portion of their length in the drift direction Y, wherein the drift direction velocity of the ions toward the second end of the ion mirrors is opposite to the electric field generated by the non-constant distance between the two ion mirrors, and wherein the electric field causes the ions to reverse their drift direction velocity near the second end of the ion mirrors and drift back toward the deflector along the drift direction.

7. The method of claim 3, 4 or 5, wherein the deflector is a first deflector, and the analyzer includes a second deflector positioned near the second end of the ion mirror, wherein the second deflector is configured to cause the ions to reverse their drift direction velocity near the second end of the ion mirror and drift back toward the deflector along the drift direction.

8. The method according to any one of claims 1-5, wherein the method includes changing the first potential in the second operating mode.

9. The method of claim 8, wherein the instrument further comprises a flight tube arranged along at least a portion of the first segment of the ion path, and wherein the method comprises changing the first potential in the second operating mode by changing the voltage applied to the flight tube.

10. The method of claim 8, wherein the method includes changing the first potential in the second operating mode by changing the acceleration field provided by the ion implanter for accelerating ions along the ion path.

11. A method of operating an analytical instrument, the analytical instrument comprising an ion analyzer, the ion analyzer being configured to analyze ions by determining the drift time of ions along an ion path, the ion path comprising at least a first segment and a loop segment, wherein the ion path is configured such that ions traverse the first segment once and traverse the loop segment once or multiple times; the method comprising: The analyzer is operated in a first operating mode, wherein in the first operating mode: (i) a first potential is provided along a first segment of the ion path, (ii) a second potential is provided along a loop segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the loop segment of the ion path has a second path length, and ions are analyzed by determining the drift time of ions along the ion path in order to obtain a first set of ion data; The analyzer is operated in a second operating mode by changing at least one of (i) the second potential and (ii) the second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a second set of ion data. The first set of ion data is compared with the second set of ion data, and the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data is identified. The number of times the cyclic segment of the ion path traversed by the ion associated with the corresponding first and second ion peaks is determined. N ;as well as The determined number of crossings N is used to determine the values ​​of the physicochemical properties of the ions associated with the corresponding first and second ion peaks.

12. The method according to claim 11, wherein: The ion analyzer is a time-of-flight (ToF) mass analyzer, and the physicochemical property is the mass-to-charge ratio (m / z); or The analyzer is an ion mobility analyzer, and the physicochemical property is ion mobility.

13. The method according to any one of claims 1-5 or 11-12, wherein the number of traversals of the loop segment of the ion path performed by the ion associated with the corresponding first and second ion peaks is determined. N include: Measure the drift time difference between the first ion peak and the second ion peak; as well as The measured drift time difference is used to estimate the number of traversals of the loop segment of the ion path performed by the ions associated with the corresponding first and second ion peaks. N .

14. A non-transitory computer-readable storage medium for storing computer software code, which, when executed on a processor, performs the method according to any one of claims 1 to 13.

15. A control system for an analytical instrument, the control system being configured to cause the analytical instrument to perform the method according to any one of claims 1 to 13.

16. An analytical instrument, comprising: An ion analyzer configured to analyze ions by determining the drift time of ions along an ion path, the ion path including at least a first segment and a loop segment, wherein the ion path is configured such that ions traverse the first segment once and traverse the loop segment once or multiple times; and The control system is configured to: In a first operating mode, the analyzer is operated and ions are analyzed by determining the drift time of ions along the ion path to obtain a first set of ion data, wherein in the first operating mode, (i) a first potential is provided along the first segment of the ion path, (ii) a second potential is provided along the cyclic segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the cyclic segment of the ion path has a second path length. The analyzer is operated in a second operating mode by changing at least one of (i) the first potential, (ii) the second potential, (iii) the first path length and (iv) the second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a second set of ion data. The first set of ion data is compared with the second set of ion data, and the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data is identified. The number of times the cyclic segment of the ion path traversed by the ion associated with the corresponding first and second ion peaks is determined. N ;as well as Use the determined number of traversals N To determine the values ​​of the physicochemical properties of the ions associated with the corresponding first and second ion peaks. The ion analyzer is a time-of-flight (ToF) mass analyzer, and the physicochemical property is the mass-to-charge ratio (m / z). The time-of-flight (ToF) quality analyzer is a multiple reflection time-of-flight (MR-ToF) quality analyzer, which includes: Two ion mirrors are spaced apart and opposite to each other in a first direction X. Each mirror typically extends along a drift direction Y between a first end and a second end, the drift direction Y being orthogonal to the first direction X. An ion implanter for injecting ions into the space between the ion mirrors, the ion implanter being positioned near the first end of the ion mirrors; and A detector for detecting ions after they have undergone multiple reflections between the ion mirrors.

17. The analytical instrument of claim 16, wherein the detector is positioned near the first end of the ion mirror, and the analyzer is configured to analyze ions by: (i) Ions are injected from the ion implanter into the space between the ion mirrors, wherein the ions complete a first cycle, in which the ions follow a plurality of paths along the first direction X between the ion mirrors. K The reflected Z-shaped ion path simultaneously: (a) drifts along the drift direction Y toward the second end of the ion mirror, (b) reverses the drift direction velocity near the second end of the ion mirror, and (c) drifts back along the drift direction Y toward the first end of the ion mirror. (ii) Reversing the drift direction velocity of the ions near the first end of the ion mirror, causing the ions to complete another cycle in which the ions travel along the first direction X between the ion mirrors. K The reflected Z-shaped ion path simultaneously: (a) drifts along the drift direction Y toward the second end of the ion mirror, (b) reverses the drift direction velocity near the second end of the ion mirror, and (c) drifts back along the drift direction Y toward the first end of the ion mirror. (iii) Repeat step (ii) once or more; and subsequently (iv) Cause the ions to travel to the detector for detection.

18. An analytical instrument, comprising: An ion analyzer configured to analyze ions by determining the drift time of ions along an ion path, the ion path including at least a first segment and a loop segment, wherein the ion path is configured such that ions traverse the first segment once and traverse the loop segment once or multiple times; and The control system is configured to: In a first operating mode, the analyzer is operated and ions are analyzed by determining the drift time of ions along the ion path to obtain a first set of ion data, wherein in the first operating mode, (i) a first potential is provided along the first segment of the ion path, (ii) a second potential is provided along the cyclic segment of the ion path, (iii) the first segment of the ion path has a first path length, and (iv) the cyclic segment of the ion path has a second path length. The analyzer is operated in a second operating mode by changing at least one of (i) the second potential and (ii) the second path length, and the ions are analyzed by determining the drift time of the ions along the ion path in order to obtain a second set of ion data. The first set of ion data is compared with the second set of ion data, and the first ion peak in the first set of ion data corresponding to the second ion peak in the second set of ion data is identified. The number of times the cyclic segment of the ion path traversed by the ion associated with the corresponding first and second ion peaks is determined. N ;as well as Use the determined number of traversals N To determine the values ​​of the physicochemical properties of the ions associated with the corresponding first and second ion peaks.

19. The analytical instrument according to claim 18, wherein The ion analyzer is a time-of-flight (ToF) mass analyzer, and the physicochemical property is the mass-to-charge ratio (m / z); or The analyzer is an ion mobility analyzer, and the physicochemical property is ion mobility.

Images