Method and apparatus for ion transfer by ion bunching

Abstract

A mass spectrometry method includes: receiving an ion flow at an inlet end of an ion transmission device; accumulating a first portion of the ion flow at a first potential well at a first position between the inlet end and an outlet end within the ion transmission device; generating a generally decreasing potential distribution within the ion transmission device between a second position and the outlet end, and simultaneously generating a second potential well at a third position within the ion transmission device, the second position being disposed between the first position and the inlet end, and the third position being disposed between the second position and the inlet end; and transmitting the accumulated first portion of the ion flow from the first position to the outlet end under the impetus of the generally decreasing potential distribution, and simultaneously accumulating a second portion of the ion flow at the second potential well.

Description

Technical Field

[0001] The present disclosure relates to mass spectrometry. More specifically, the present disclosure relates to ion transfer in the presence of a background gas in a pressure range of 1 mTorr up to tens of Torr. Background Art

[0002] In mass spectrometry applications, it is often important to transport ions quickly and efficiently through regions where the background gas pressure ranges from 1 mTorr up to tens of Torr (e.g., 80 Torr). Since ion motion under these conditions is determined by the mobility in the gas, the potential gradient along the beam path must be increased to reduce ion drift time. If the ion path is quite long, a large total potential difference may be required. This can cause problems because some elements cannot easily float to a high potential relative to ground.

[0003] For example, Giles et al. explained in U.S. Pat. No. 9,978,572 that the accumulation effect of multiple potential steps between adjacent components of a mass spectrometer system may cause an unacceptably large voltage to appear in an upstream component in the presence of a gas. This problem is schematically shown in a general sense in FIG. 1A, which relates to a system configuration 100 of a mass spectrometer system, which includes a first upstream device 3, a second upstream device 4, a gas-filled collision cell 5, and a downstream device 6. The dotted line 8 represents the electrical breakdown limit. The position along the instrument is depicted from left to right, and the potential at the position is represented by the vertical axis. In order to cause fragmentation, a potential difference is introduced between the upstream devices 3, 4 and the collision cell 5 by increasing the absolute potential applied to the upstream devices 3, 4. The potential distribution across the system is schematically shown by dotted lines 101. The increased potential of the upstream device accelerates the ions emerging from the second upstream device 4 through the potential difference (denoted as "CE" in FIG. 1A) between the outlet of the second upstream device 4 and the entrance of the collision cell 5. The collision energy is mainly determined by this potential difference. However, the potential increase may cause the voltage applied to the upstream device 3, 4 to be above the electrical breakdown limit 8. Although the discussion of Giles et al. specifically concerns large potentials and potential gradients due to the need to transfer collision energy to ions, similar problems may arise when applying large potential gradients to transport ions through regions with background pressure.

[0004] In order to avoid such complications, several solutions have been proposed. For example, Giles et al. in the aforementioned U.S. Patent No. 9,978,572 teach the application of a potential to produce a reverse axial DC electric field and the generation of a "traveling wave" that drives ions to reverse the corresponding potential gradient. This method is schematically shown in Figures 1B and 1C currently attached. As depicted by the system configuration 1 shown in Figure 1B, the potential difference (CE) required for collision-induced dissociation can be introduced, at least partially introduced, by applying a reverse axial DC electric field to the collision cell 5. The reverse axial electric field provides an increased axial potential in the downstream direction, so that the potential at the outlet of the collision cell 5 is increased relative to the potential at the entrance. Therefore, the potential drop that limits the collision energy is located in the area around the entrance of the collision cell 5. In order to transmit ions from the collision cell 5 to the downstream device 6, the ions must be driven to reverse the axial electric field. This effect can be achieved if the collision cell includes multiple electrodes and / or is segmented in the axial direction so that an independent transient DC potential or voltage waveform can be applied to each segment. The transient DC potential or voltage waveform applied to each segment generates a traveling wave 7 that moves in the axial direction and thereby pushes or propels the ions upward or against the potential gradient of the reverse axial electric field. As an alternative, the required collision energy (CE) can be provided by generating a reverse axial DC electric field in the upstream component 4, as schematically depicted in the system configuration 120 shown in FIG. 1C. In this case, the traveling wave is generated in the upstream component 4.

[0005] Alternative methods for transporting ions through a gas-containing region of a mass spectrometer involve using a gas flow as the "driving force" for ion transport. In practice, however, the implementation of traveling wave or gas flow transport mechanisms is very complex to implement, both in terms of ion motion timing, technical feasibility, and cost effectiveness, and may not be suitable for all systems. Summary of the invention

[0006] According to the teachings of the present invention, the reduction of the potential gradient can be achieved by interrupting the continuity of the ion flow. The ions in the incoming ion flow are bunched into individual spatially separated packets to allow a reverse gradient region in which no ions are present to be temporarily generated within the ion transport device. In this way, the region between packets within the ion transport device can be temporarily raised to a potential similar to the potential of the ion inlet of the ion transport device, thereby allowing individual ion packets to migrate forward while reducing the overall gradient across the ion transport device and the entire instrument.

[0007] Therefore, in a first aspect of the present teachings, there is provided a mass spectrometer system, the mass spectrometer system comprising:

[0008] Ion source;

[0009] Mass analyzer;

[0010] An ion transmission device, the ion transmission device is arranged between the ion source and the mass analyzer, the ion transmission device comprising:

[0011] an ion inlet having an inlet electrode at the ion inlet and disposed at a longitudinal position X0;

[0012] An ion outlet having an exit electrode at the ion outlet and arranged at a longitudinal position X L and

[0013] a plurality of annular or plate-shaped electrodes, the plurality of annular or plate-shaped electrodes being disposed between the inlet electrode and the outlet electrode;

[0014] one or more power supplies electrically coupled to the inlet electrode and the outlet electrode and to the plurality of ring or plate electrodes; and

[0015] A computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to:

[0016] supplying an oscillating radio frequency (RF) voltage to each of the plurality of ring or plate electrodes, wherein the RF phase supplied to each electrode is out of phase by π radians relative to the RF phase supplied to each adjacent electrode; and

[0017] Repeat the following steps:

[0018] (a) providing a first corresponding direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes, the plurality of first DC voltages defining a first potential distribution, the first potential distribution at the longitudinal position X k The ion trapping potential well is defined at X0 <X k <X L ;as well as

[0019] (b) providing a second corresponding DC voltage to each of the plurality of annular or plate-shaped electrodes, the plurality of second DC voltages defining a second potential distribution, the second potential distribution at position X k The axial field is directed to push the ions toward the exit electrode, and the plurality of second DC voltages are further directed at the longitudinal position X. i The trapping potential well is defined at <X i <X k .

[0020] According to a second aspect of the present invention, there is provided a second mass spectrometer system comprising:

[0021] Ion source;

[0022] Mass analyzer;

[0023] An ion transmission device, the ion transmission device is arranged between the ion source and the mass analyzer, the ion transmission device comprising:

[0024] an ion inlet having an inlet electrode at the ion inlet and disposed at a longitudinal position X0;

[0025] An ion outlet having an exit electrode at the ion outlet and arranged at a longitudinal position X L and

[0026] A plurality of multipolar sections, the plurality of multipolar sections being disposed between the inlet electrode and the outlet electrode, each multipolar section comprising a corresponding plurality of mutually parallel rod electrodes;

[0027] one or more power supplies electrically coupled to the entrance electrode and the exit electrode and to the plurality of rod electrodes of each multipolar section; and

[0028] A computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to:

[0029] supplying an oscillating radio frequency (RF) voltage to each rod electrode of each multipolar segment, wherein within each multipolar segment, the RF phase supplied to each rod electrode of the segment is out of phase by π radians relative to the RF phase supplied to each adjacent rod electrode of the segment; and

[0030] Repeat the following steps:

[0031] (a) providing a first respective direct current (DC) voltage to all rod electrodes of each multipolar segment of the plurality of multipolar segments, the plurality of first DC voltages defining a first potential distribution, the first potential distribution at a longitudinal position X k The ion trapping potential well is defined at X0 <X k <X L ;as well as

[0032] (b) providing a second respective DC voltage to all rod electrodes of each multipolar segment of the plurality of multipolar segments, the plurality of second DC voltages defining a second potential distribution, the second potential distribution at position X k The axial field is directed to push the ions toward the exit electrode, and the plurality of second DC voltages are further directed at the longitudinal position X. iThe trapping potential well is defined at <X i <X k .

[0033] According to a third aspect of the present teachings, there is provided a method for transmitting ions in a mass spectrometer, the method comprising:

[0034] receiving a continuous flow of positively charged ions at an inlet end of an ion transport device, the ion transport device further comprising an outlet end;

[0035] causing a first portion of the ion flow to accumulate at a first potential well within the ion transport device at a first location between the inlet end and the outlet end, the accumulation being driven by a potential difference between the first location and the inlet end;

[0036] creating a generally decreasing potential distribution within the ion transport device between a second location disposed between the first location and the inlet end and the outlet end, and simultaneously creating a second potential well at a third location within the ion transport device, the second location disposed between the first location and the inlet end, the third location disposed between the second location and the inlet end; and

[0037] An accumulated first portion of the ion flow is transported from the first position to the outlet end under the impetus of the generally decreasing potential distribution, and a second portion of the ion flow is simultaneously accumulated at the second potential well, the accumulation of the second portion of the ion flow being driven by the potential difference between the third position and the inlet end.

[0038] According to a fourth aspect of the present teachings, there is provided a system for analyzing a sample, the system comprising:

[0039] an ion source configured to generate ions from constituent components of the sample;

[0040] a mobility separator configured to separate the ions received from the ion source based on their respective mobilities in a gas, the mobility separator providing a gas flow in a first direction and an electric field gradient in a second direction so that the ions move in the first direction and drift according to the mobility of the ions in the second direction so that the ions are classified according to their respective mobilities;

[0041] a plurality of ion transfer devices arranged adjacent to the mobility separator such that ions from the mobility separator are directed to different ion transfer devices according to respective mobilities of the ions, each ion transfer device comprising:

[0042] an exit ion gate operable to release ions from the ion transport device through an outlet of the ion transport device or to prevent ions from being released from the ion transport device through an ion outlet of the ion transport device;

[0043] a mass analyzer configured to receive ions from the ion outlet of each ion transmission device; and

[0044] One or more power supplies electrically coupled to the mobility separator and the plurality of ion transport devices.

[0045] In various embodiments, the system for analyzing the sample may further include a computer or electronic controller electrically coupled to the one or more power supplies and including computer-readable instructions operable to cause the one or more power supplies to execute the following: operate the multiple exit gates such that ions are released from one or more of the exit gates at any one time. In various embodiments, the system for analyzing the sample may further include a computer or electronic controller electrically coupled to the one or more power supplies and including computer-readable instructions operable to cause the one or more power supplies to execute the following: operate the multiple exit gates such that ions received from the mobility separator accumulate in each ion transmission device for a corresponding accumulation duration, wherein the multiple accumulation durations are not exactly the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and various other aspects of the invention will become apparent from the following description, given by way of example only and with reference to the accompanying drawings, which are not necessarily drawn to scale, in which:

[0047] FIG1A is a schematic depiction of potentials applied to components of a mass spectrometer during collision induced dissociation according to well-known conventional methods;

[0048] FIG. 1B is a schematic depiction of applied potentials during collision-induced dissociation according to known methods for transferring ions through a mass spectrometer;

[0049] FIG1C is a schematic depiction of applied potentials during collision induced dissociation according to a known alternative method for transferring ions through a mass spectrometer;

[0050] Figure 2A is a schematic depiction of a stacked annular ion guide in the form of an ion tunnel on which the method according to the teachings of the present invention may be implemented;

[0051] FIG2B is a schematic depiction of a first exemplary ring or plate electrode;

[0052] FIG2C is a schematic depiction of a second exemplary ring or plate electrode;

[0053] Figure 2D is a schematic depiction of a stacked annular ion guide in the form of an ion tunnel and an ion funnel on which the method according to the teachings of the present invention may be implemented;

[0054] Figure 3A is a schematic depiction of another exemplary ion transport device upon which methods according to the teachings of the present invention may be implemented;

[0055] Figure 3B is a schematic depiction of yet another exemplary ion transport device upon which methods according to the teachings of the present invention may be implemented;

[0056] Figure 4A is a schematic depiction of a first example potential profile that may be applied across the length of an ion transfer device during an operating phase of the device in accordance with the teachings of the present invention;

[0057] Figure 4B is a schematic depiction of example potential profiles that may be applied across the length of an ion transfer device during different stages of operation of the device in accordance with the teachings of the present invention;

[0058] Figure 4C is a schematic depiction of example potential profiles that may be applied across the length of an ion transfer device during still different stages of operation of the device according to some embodiments of the present teachings;

[0059] Figure 4D is a schematic depiction of example potential profiles that may be applied across the length of an ion transfer device during yet further different operating stages of the device in accordance with some embodiments of the present teachings;

[0060] Figure 5A is a schematic depiction of an example potential profile that may be applied across the length of another ion transfer device during an operating phase of said device in accordance with the teachings of the present invention;

[0061] Figure 5B According to the teachings of the present invention, the device can be switched during different operating phases. Figure 5A Schematic depiction of an example potential profile applied along the length of the indicated ion transfer device;

[0062] Fig. 6A is a schematic depiction of a first mass spectrometer system according to the teachings of the present invention, the first mass spectrometer system comprising an ion mobility separation apparatus and an ion transfer device according to the teachings of the present invention;

[0063] Figure 6Bis a schematic depiction of a second mass spectrometer system according to the teachings of the present invention, the second mass spectrometer system comprising an ion mobility separation apparatus and an ion transfer device array according to the teachings of the present invention; and

[0064] Figure 6C yes Figure 6B A magnified portion of an array of ion transfer devices. DETAILED DESCRIPTION

[0065] The following description is presented to enable one skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles herein may be applied to other embodiments. Therefore, the present invention is not limited to the embodiments and examples shown, but is consistent with the maximum possible scope according to the features and principles shown and described. In order to fully understand the features and advantages of the present invention in more detail, please refer to Figures 1A-1B; 2A-2D-3A-3B, 4A-4D, 5A-5B and 6A-6C in conjunction with the following description.

[0066] In the description of the present invention herein, it should be understood that words appearing in the singular cover their plural counterparts, and words appearing in the plural cover their singular counterparts, unless otherwise implicitly or explicitly understood or stated. In addition, it should be understood that, unless otherwise implicitly or explicitly understood or stated, for any given component or embodiment described herein, any possible candidate or alternative listed for the component can generally be used individually or in combination with each other. It will be understood that, unless otherwise implicitly or explicitly understood or stated, any list of candidate or alternative is merely illustrative, not restrictive. In addition, it should be understood that the drawings as shown herein may not be drawn to scale, wherein only some elements may be drawn for the clarity of the present invention. And, figure numerals may be repeated in each figure to show corresponding or similar elements.

[0067] As used herein, when the term "DC" refers to a voltage applied to one or more electrodes of a mass spectrometer component (such as an ion funnel), it does not necessarily mean that a current is applied or present through these electrodes, but is only used to indicate that the applied voltage is static, or if non-static, non-oscillating and non-periodic. Therefore, the term "DC" is used herein to distinguish the referenced voltage from an applied periodic oscillating voltage, which itself may be referred to as an "RF" or "AC" voltage.

[0068] Figure 2A is a schematic depiction of a known ion transport device 20 upon which the methods according to the teachings of the present invention may be implemented. Figure 2AAs shown, the ion transport device 20 includes a stacked annular ion guide in the form of an ion tunnel. Generally described, the ion tunnel device 20 includes a substantially constant diameter θ T A plurality of closely longitudinally spaced ring or plate electrodes or ring electrodes 42 having an aperture of θ defining an interior hollow volume 43 in which the ions are restrained by electrostatic forces. Preferably, the diameter θ T In the range of 4-10 mm, inclusive.A set of ring or plate electrodes 42 may be positioned between the entrance electrode 12 and the exit electrode 13, one or both of which may include an ion lens or ion gate to focus the ion flow and / or control the timing of ion flow into the device.

[0069] According to a well-known mode of operation of the apparatus 20, a constant amplitude radio frequency (RF) voltage waveform is applied to all of the ring or plate electrodes 42, with every other electrode receiving a first RF phase and all remaining electrodes receiving a second RF phase that is completely out of phase (i.e., a phase difference of π radians) with the first RF phase. Under such operation, the pseudopotential between adjacent plate or ring electrodes confines the ions near the central longitudinal axis 47. According to many modes of operation, the forward motion of the ions in the general direction from the ion entrance electrode 12 to the ion exit electrode 13 is driven by the flow of an inert background gas such as nitrogen or helium. However, in accordance with the teachings of the present invention, as further described below, the ions are urged primarily in the forward direction by applying an axial electric field (sometimes referred to as a drag field).

[0070] 2B and 2C are schematic depictions of exemplary individual ring or plate electrodes 42.1, 42.2 of different forms, as viewed toward their faces. Each electrode comprises a body of material 111a, 111b or a ring or plate form having an aperture 118 defined by an aperture surface 113 of preferably circular form. The electrode body 111a, 111b may include a socket slot that cooperates with a positioning holder, frame or railing (not shown) for holding a plurality of such electrodes (such as in Figure 2A Ion tunneling device 20 or Figure 2D The electrode bodies 111a, 111b may be electrically coupled to a power source via hooks, tabs or fasteners. Alternatively, separate electrical leads (not shown) may provide electrical coupling.

[0071] Figure 2D is a schematic depiction of another known ion transport device 120 upon which the methods according to the teachings of the present invention may be implemented. Figure 2DAs shown, the ion transmission device 120 includes an ion funnel device as taught in U.S. Pat. No. 9,761,427. Similar to the ion tunnel device 20, the ion funnel device 120 includes a plurality of closely spaced longitudinally plate-like or ring-like electrodes 42 having an aperture defining an internal hollow volume. However, unlike the device 20, the ion funnel device 120 further includes an ion funnel portion 44 of the internal volume in addition to the ion channel portion 43 of the internal volume. The ion tunnel portion 43 of the internal volume corresponds to a common constant aperture diameter θ. T The ion funnel portion of the interior volume corresponds to a second electrode set 49b including an aperture of variable diameter θ that decreases gradually along the length of the funnel portion 44 as the ion exit aperture 46 of the device is approached. The second electrode set 49b focuses the ions into a narrow beam that passes through the funnel ion exit aperture 46 and through the aperture 48 in the chamber divider 55 into the adjacent mass spectrometer chamber.

[0072] Figure 3A 1 is a schematic depiction of another ion transport device on which the method according to the teachings of the present invention can be implemented. The ion transport device 10 is a segmented multipole device or a multiple multipole device including an inlet electrode 12, an outlet electrode 13, a plurality of multipole segments (e.g., "multipole segments") 11a, 11b, 11c, 11c, 11d, and a plurality of potential distribution control electrodes 14a, 14b, 14c, each of which is disposed between two multipole segments in the multipole segment. In a known manner, each multipole segment includes a plurality of rod electrodes parallel to each other.

[0073] The device 10 may further include gate electrodes at different locations between the entrance electrode and the exit electrode. One such gate electrode, in particular the exit gate electrode 15, may be disposed near the exit electrode 13. One or more additional gate electrodes may be disposed between multipoles or multipole segment pairs. For example, Figure 3A As shown, a gate electrode 16a can be placed adjacent to the first potential distribution control electrode 14a and between the multipole segments 11a, 11b. One or more power supplies 54 are electrically coupled to the multipole rods, the entrance and exit electrodes, the potential distribution control electrode, and the gate electrode. The one or more power supplies 54 are configured to provide an oscillating radio frequency (RF) voltage to the multipole rods of the multipole segments 11a-11d in a known manner, wherein the RF phase of the voltage applied to each rod is exactly out of phase with the RF phase of the voltage applied to each adjacent rod (i.e., the phase difference is π radians). As shown Figure 3ASchematically shown, one or more power supplies 54 can also be configured to provide non-oscillating DC offset voltages to other electrodes 12, 14a-14c and 13 and to the rod electrodes of multipole sections 11a-11d. In the latter case, the same DC bias potential is applied to all rods in each multipole section. The non-oscillating DC bias potential applied to the rod electrodes is superimposed on the applied oscillating RF potential.

[0074] The timing of application of the various voltages is controlled by a computer or other digital logic controller 52 electrically coupled to one or more power supplies 54. The computer or other digital logic controller 52 includes computer readable instructions located in firmware or software (or both) and permanent memory or and / or transient memory as retrieved from a remote or local information storage device, such as a floppy disk or hard disk, flash memory device, etc. Under the control of the computer readable instructions, the computer or other digital logic controller 52 sends control signals to the one or more power supplies 54, which causes the one or more power supplies to supply a controlled sequence of controlled voltages to the electrodes of the device 10, which causes the device to operate in accordance with the teachings of the present invention, as described below.

[0075] In operation, an ion stream 17 enters the device 10 through the entrance electrode 12. The entrance electrode 12 may include an ion lens or ion gate that focuses the ion stream and / or controls the timing of the ion stream entering the device. After passing through the entrance electrode 12, the ions are radially confined within each quadrupole segment by the action of an RF voltage applied to the rod electrodes of the segment. Within the device, radial confinement of the ions is maintained by pseudopotentials generated by applying RF voltages to the rod electrodes of the multipole segments 11a-11d. The forward movement of the ions through the device is driven primarily by applying a DC bias potential difference between each multipole segment and its adjacent electrodes, such as Figure 3A Finally, by operation of the apparatus 10 as further described below, the ions of the original ion flow are bunched into spatially isolated discrete ion packets 19, which exit from the outlet end of the apparatus. In the absence of axial field generating electrode structures within the multipole segments, the potential distribution segments within each multipole segment are substantially flat (e.g., Figure 3A ) and the continued forward motion of ions within the multipole segment depends on the kinetic energy of the ions introduced into the segment. Alternatively, as discussed below, the axial field generating electrode structure can be incorporated into some or all of the multipole segments.

[0076] Figure 3B is a schematic depiction of yet another exemplary ion transport device 110 on which methods according to the teachings of the present invention may be implemented. Figure 3A ) is similar, device 110 ( Figure 3B ) includes multiple multi-pole segments. Figure 3BFour such multipolar segments 11a - 11d are depicted in FIG, but the total number of such multipolar segments is not limited or constrained to any particular value. Figure 3B Device 110 and Figure 3A The device 10 of FIG. 1 is different in that one or more of the potential distribution control electrodes 14a, 14b, 14c of the device 10 are removed from the device 110. Instead of using the distribution control electrodes 14a, 14b, 14c to control the ion flow, the device 110 uses a plurality of axial field generating structures 111a-111d for this purpose. Each of the axial field generating structures 111a-111d is associated with a corresponding multipole segment. Although in FIG. Figure 3B Four such axial field generating structures are depicted in , but the device 110 may include an axial field generating structure in conjunction with each of the multipole sections of the device.

[0077] Typically, each axial field generating structure generates an axial electric field along the central axis of each multipole segment, which urges the ions within the multipole to move parallel to the axis in a general direction toward the exit gate electrode 15. Many types of axial field generating structures are known in the art. Many such axial field generating structures, such as Figure 3B The axial field generating structure 111a-111d depicted in the figure is electrically coupled to a first electrical lead 112 disposed at the upstream end of the multipole section and a second electrical lead 115 disposed at the downstream end of the multipole section, the two electrical leads being electrically coupled to a power source 54. To generate the axial field, the voltage difference provided between the two leads is then gradually or continuously separated or proportional along the length of the axial field generating structure. For example, commonly assigned U.S. Patent No. 7,675,031 teaches the use of a set of auxiliary rod electrodes to generate a resistance field. The auxiliary electrodes can be arranged as an array of finger electrodes disposed between the rod electrodes in each multipole section. As another example, U.S. Patent No. 5,847,386 teaches the use of a set of auxiliary rod electrodes, which are mounted parallel to each other and mounted to the multipole carrying RF in the space between the multipole rods. Each of the auxiliary rods has an insulating core with a surface layer of resistive material. The voltage applied between the two ends of each auxiliary rod establishes a potential gradient from one end to the other. Alternative methods for generating an axial field within a multipole device include the use of tapered multipole rod electrodes, the use of non-parallel multipole rod electrodes (two methods taught in US Pat. No. 5,847,386), and other techniques.

[0078] For simplicity, the following uses a controlled potential distribution ( Figures 4A-4D The discussion of ion transport of 5A-5B) specifically relates to ion transport device 10 ( Figure 3A), is used as an example only. However, one of ordinary skill in the art will readily understand how to apply the general principles of ion transport as taught below to the operation of other types of ion transport devices, such as Figure 3B The multi-pole segment ion transport device 110 shown in Figure 2A The ion tunnel ion transport device 20 shown or Figure 2D An ion funnel ion transport device 120 is shown. In each type of device, a computer or other digital logic controller 52 can control the temporal and spatial variation of the potential distribution by sending control signals to one or more power supplies 54. These control signals cause the one or more power supplies to provide controlled DC potentials to various potential distribution control electrodes, to certain selected plate or ring electrodes of an ion tunnel or ion funnel device, or to any other form of axial field generating structure.

[0079] Figures 4A-4B Details regarding the timing and distribution of the applied potential V are shown according to the first method taught by the present invention. In this example, Figures 4A-4B 71, 72 are graphs of potential across the length of a device of length L having an ion inlet at position X0 and an ion outlet at position X4. Position X0 is the position at the device inlet where the axial variable X takes zero. The potential gradient is generated by providing a controlled DC potential to the potential distribution control electrodes 14a, 14b, 14c. As indicated in the figures, the corresponding position along the X axis at the device outlet may alternatively and more generally be represented as position X L (rather than position X4 in the particular example shown). Figure 4A and 4B The potential distribution at time points t1 and t2 are shown, respectively, where t2 is a later time than t1. Ions enter the device from the left, usually but not necessarily after leaving the atmospheric pressure interface or some part of the high-pressure ion separator such as the ion mobility device. After the ions exit the device, they continue downstream toward other optical components and eventually reach the mass spectrometer for analysis and detection.

[0080] The positions X1, X2 and X3 along the X-axis are the locations of discontinuities (or otherwise rapid changes) in the direction of the axial electric field vector within the device. These positions may correspond to the locations of internal ion lenses or gates 14a, 14b, 14c, 15, 16a, etc., such as Figure 3A As shown, or alternatively, may correspond to Figure 2DThe positions of certain plate electrodes (plate electrode 49a or plate electrode 49b) are shown at which there is a reversal in the sign of the rate of change of the applied potential as a function of X. Positions X0 and X4 are the locations of the inlet electrode 12 and outlet electrode 13 of the device, respectively. Regions 31, 32, 33 and 34 are defined between positions X0 and X1, between positions X1 and X2, between positions X2 and X2, and between positions X3 and X4, respectively. Since the electronic controller 52 ( Figure 2D-3A ) by applying individual potentials or potential distributions to the electrodes of the device by one or more power supplies 54 under the control of the axial electric field, which can vary between regions.

[0081] In the following discussion, it is assumed that positively charged ions pass through the transfer device according to the teachings of the present invention. Under this assumption, the positive ions migrate along the potential gradient. The same argument can be easily adapted to the transfer of negative ions by reversing the polarity of the applied potential.

[0082] In operation according to the first method, the potential distribution is similar to Figure 4A The distribution shown in 71 and Figure 4B . Distribution 71 includes distribution segments 61 and 62 and distribution 72 includes distribution segments 63, 64 and 65. The ends of a distribution segment correspond to a breakpoint in the slope of the complete distribution to which the segment belongs.

[0083] although Figures 4A-4D Each distribution segment shown in is depicted as a single continuous line of constant slope, but in most cases such depictions are idealized approximations. For example, if Figure 4A The distribution segment 61 represents the potential of the ring electrodes between the ring electrode 90 (at position X0) and the ring electrode 93 (at position X3) of the transfer device 20, then in practice, an approximation to the linear distribution segment can be achieved by applying a potential V0 to the ring electrode 90 and a potential V1 to the ring electrode 93 and allowing a voltage divider circuit to linearly distribute the potential difference (V1-V0) applied between the intermediate ring electrodes, wherein a different potential is applied to each respective ring electrode. Therefore, in this example, Figure 4A The linear approximation depicted in is valid only in the limit of infinitely thin ring electrodes.

[0084] As another example, if you use Figure 3A The transmission device 10, the potential distribution 171 ( Figure 5A ) and 172( Figure 5B) are analogs of distributions 71 and 72, respectively. Assuming that there is no axial electric field along the length of the multipole, the long horizontal segments of distributions 171 and 172 correspond to the locations of multipole segments 11a, 11b, 11c, 11d. The shorter horizontal segments of the distributions correspond to the locations of potential distribution control electrodes 14a, 14b, 14c. The inclined segments of the distributions correspond to the spacing between components.

[0085] In alternative apparatus embodiments, the potential distribution control electrodes of transfer apparatus 10 may be eliminated in favor of a greater number of shorter length multipole segments. In such embodiments, as the rod segments become shorter, distributions 171 and 172 will be closer to distributions 71 and 72, respectively. In other alternative apparatus embodiments, the potential distribution control electrodes of transfer apparatus 10 may be eliminated, and an axial electric field may be provided along the length of each multipole segment by employing any of a variety of known techniques, including the use of tapered or angled rod electrodes, the incorporation of resistive auxiliary rod electrodes between and parallel to the multipole rod electrodes, the insertion of a series of auxiliary blade electrodes between the multipole rods at various locations along the length of the multipole rods, and the like. In such other alternative apparatus configurations, the potential distribution may be very close to distributions 71 and 72. Figures 4A-4D The complete distribution segment of the distribution depicted in .

[0086] The potential distribution 171 includes a generally decreasing distribution section 161 indicated by a dashed line between longitudinal positions X1 and X3 and a generally increasing distribution section 162 indicated by a dashed line between longitudinal positions X3 and X4. The potential distribution 172 includes a generally decreasing distribution section 163 indicated by a first dashed line between longitudinal positions X0 and X1, a generally increasing distribution section 164 indicated by a dashed line between longitudinal positions X1 and X2, and a second generally decreasing distribution section 165 indicated by another dashed line between longitudinal positions X3 and X4. As used in this document, the term “at position X1” refers to a generally decreasing distribution section 163 between longitudinal positions X0 and X1, a generally increasing distribution section 164 between longitudinal positions X1 and X2, and a generally decreasing distribution section 165 between longitudinal positions X3 and X4. a With position X b When applied to X b >X a When the distribution segment is at position X a With position X b The first-order derivative of the distribution segment is not greater than zero at all points between the first-order derivative and the distribution segment. Similarly, as used in this document, the term "at position X a With position X b When applied to X b >X a When the distribution segment is at position X a With position X b At all points between which the first-order derivative is defined, the first-order derivative of the distribution segment is not less than zero.

[0087] Furthermore, as used in this document, a first potential distribution is said to be similar to a second potential distribution if: (a) the first distribution and the second distribution each consist of the same sequence of generally decreasing and generally increasing distribution segments, or (b) the mirror images of the first distribution and the second distribution each consist of the same sequence of generally decreasing and generally increasing distribution segments. Thus, according to this usage, distribution 72( Figure 4B ) is similar to distribution 172( Figure 5B ), because the distributions are composed of a first generally descending distribution segment, followed by a generally ascending distribution segment, followed by a generally descending distribution segment. Distribution 72 will also resemble a mirror image distribution, with generally ascending distribution segments replacing generally descending distribution segments, and vice versa, so as to transport negative polarity ions along the length of the transfer device from X=0 to X=L.

[0088] Return to Figures 4A-4D The voltage applied to the electrodes is such that at the beginning of each cycle (time t1), the potential distribution is similar to Figure 4A The distribution 71 shown in . The distribution is maintained within a first duration period τ1. During this first time period, the falling potential distribution (distribution segment 61 of distribution 71) allows ions to travel from the device entrance (at position X0) to position X3, where there is a reversal of the potential gradient. Therefore, at this position, additional forward migration of ions is prevented, and therefore, ions accumulate near the potential well (at potential V1), which is formed by the intersection of distribution segment 61 and distribution segment 62. The number of ions accumulated in the potential well during the duration τ1 depends at least in part on the ion flux delivered to the entrance of the transfer device and the accumulation duration τ1. If the interior of the transfer device is under considerable gas pressure, the number of accumulated ions may also depend on the mobility of the ions and the potential gradient of distribution segment 61.

[0089] At time t2, the potential applied to the electrodes is changed so that the potential distribution is similar to Figure 4B . In this configuration, the applied potential at positions X0 and X3 is raised above the exit potential at X4 to provide a downwardly sloping potential distribution segment 65. The reconfiguration of the potential distribution requires a switching time of duration δ. The configuration of distribution segment 65 allows previously accumulated ions to be transferred out of the device through its exit. At the same time, newly arrived ions migrate along distribution segment 63 and arrive at position X3, where they accumulate near a new potential well at a potential V2, which is defined by the intersection of distribution segment 63 with distribution segment 64. Figure 4BThe distribution configuration shown in is maintained for a duration τ2, which is selected so that all ions in regions 33 and 34 can travel past position X4. The potential distribution can be configured so that τ2<τ1 by selecting the width of region 34 to be smaller than the combined width of regions 31 and 32 and / or by configuring the potential gradient of distribution segment 65 to be greater than the potential gradient of distribution segment 63. Subsequently, the next cycle begins and the above operations are repeated as described above, except that Figure 4A The next and all subsequent instances of the potential distribution 71 depicted in are maintained for a duration τ3 (rather than τ1), where τ3≈τ1-τ2. Shorter accumulation times τ3 for iterations after the first are possible due to the fact that the ions have accumulated for a period of time τ2 at the potential well of potential V2. By this iterative process, the initial continuous beam is divided into a plurality of ion packets, which are emitted from the outlet of the transfer device to the downstream mass spectrometer components. Successive packets are separated by intervals of duration 2δ+τ3≈2δ+(τ1-τ2). If τ2≈τ1, the intervals are relatively small.

[0090] Alternatively, if it may be beneficial under some experimental conditions to compress the ion population from an initial continuous stream into shorter packets, then at the outlet of the transfer device (e.g., at position X4, such as Figure 4C Additional gating (schematically in ) would achieve this goal. Figure 3A The exit gate 15 depicted in is an example of such an exit gate. The type of gate employed may be selected from a variety of gate types known in the art. A simple choice is a simple metal plate with a circular opening. If the potential across the lens is raised, ions cannot pass through and the gate is "closed". The gate may be closed at or before time t2 and then for a period of time τ2. The exit gate may be closed by raising its applied potential to a value V4 which is greater than the normal exit potential V0 of the device (see Figure 4B ). Therefore, the potential profile includes an additional profile segment 66 that causes ions to accumulate before the exit gate. The potential applied to the gate is then reduced to V0 (or possibly lower) for an additional duration, thereby sending narrow ion packets downstream. It is necessary to have sufficient field gradient near the gate to keep the transit time (τ4) of the ion packet out of the device short for a short duration.

[0091] Figures 4A-4C The combination of the potential profiles depicted in can be used in a second method for transferring ions according to the teachings of the present invention. According to the second method, the first cycle of the sequence of events begins at time t1, wherein the configuration and Figure 4A The potential distribution across the length of the device is similar to the distribution 71 depicted in . This distribution is maintained for an initial duration period τ1, during which a first set of ions (including a first ion packet) accumulates near the potential well at potential V1 and at position X3.

[0092] After the initial time period (i.e., at time t2), during the second duration τ2, Figure 4C The potential distribution is similarly configured as the distribution 73 depicted in FIG. When the potential distribution is in this second configuration, the ions in the first ion packet are transferred through regions 33 and 34 and re-accumulated at the potential well at the potential V0 of the exit gate (at or near position X4). This potential well is defined by the discontinuity between the distribution segment 65 and the distribution segment 66, the latter of which is the potential of the exit gate. At the same time, the second ion set including the second ion packet accumulates near the potential well at the potential V2 and at the position X2.

[0093] Subsequently, at time t3, the potential of the exit gate drops to a value equal to or lower than potential V0 for a duration of at least τ3. This reconfiguration produces Figure 4B 72 shown in the potential distribution of the general form. During this third time period, the ions in the first ion packet are emitted out of the transfer device through its outlet. In addition, during this third time period, the ions continue to accumulate in the second ion packet near the potential well at the potential V2 and at the location X2.

[0094] After the third time period has expired, the potential distribution is reconfigured to again conform to Figure 4A The general form of the distribution 71 depicted in FIG. This reconfiguration produces a second cycle of the sequence of events described above, according to a second method for transferring ions. The second cycle and all subsequent cycles are as described above for the initial sequence of events, except that Figure 4A The second and all following instances of application of the potential configuration depicted in are maintained for a duration τ4 (instead of τ1), where τ4≈τ1-(τ2+τ3).

[0095] In a variation of the second method, the implementation of the potential distribution 73 may occur only at certain times during the transfer of ions from the inlet of the transfer device to its outlet. In such cases, the bunching of ions is performed selectively. For example, in the case of an ion stream whose composition varies with time input to the inlet of the transfer device, it may be necessary to bunch only ion species of certain components of analytical interest. When such ion species of interest are input (or expected to be input) to the transfer device, then the ions are bunched together. Figure 4C, the axial potential profile across the length of the device will be configured with the exit gate "closed" at position X4, similar to the profile 73 shown in FIG. This will cause the ions of interest, if present, to bunch into concentrated packets that can then be analyzed by a downstream mass analyzer with greater accuracy and more sensitive detection than would otherwise be possible. At other times, when no ion species of interest are expected or when detection sensitivity is not an issue, applied potential profiles similar to profiles 71 and 72 may be alternated without closing the exit gate at position X4.

[0096] In an alternative device configuration, an ion gate may be provided at a location within the device. For example, Figure 3A ion gate 16a depicted in FIG. 7 can achieve such a function. When such an ion gate is configured in its "off" configuration, as depicted by potential profile 74, ions can bunch within the ion transfer device by accumulating at a location just in front of the ion gate. Then by subsequently configuring a device similar to profile 71 ( Figure 4A ) and then configure a potential distribution similar to distribution 72 ( Figure 4B ) potential profile, bunched ions can be transferred to its outlet through the device as spatially discrete packets. During continuous operation, the potential profile can be repeatedly cycled through profiles similar to profiles 74, 71 and 72. For the reasons described above, some of the cycles may omit the implementation of a profile similar to profile 74.

[0097] The potentials applied to the entrance and exit electrodes (at X0 and X4, respectively) may be fixed, either relative to one another or in an absolute sense, but not necessarily so. As described in the Background and Summary sections of this document, it is generally desirable to minimize potential gradients between mass spectrometer components and across any individual such component to prevent excessive voltage at either end of the ion path. Figures 4A-4D as well as Figure 5A-5B In the example above, it is assumed that the applied potential at the entrance electrode and the exit electrode is the same. However, the exit electrode potential may be higher or lower than the entrance electrode potential. Further, during mass analysis, the potential applied to the entrance electrode or the exit electrode or to both electrodes may vary with time, depending on the requirement (if any) to adjust the potential difference between the ion transmission device and the upstream or downstream components. If one or both of the potentials applied to the entrance electrode and the exit electrode are varied with time during mass analysis, the potential applied to the internal electrode may also be simultaneously varied to maintain a constant internal potential gradient (e.g., the slope of the axial potential distribution segments 61, 61a, 61b, and 62-67).

[0098] Fig. 6Ais a schematic depiction of an ion mobility and mass spectrometry system 130 in accordance with the teachings of the present invention. Various types of ion mobility separation (IMS) devices—including trapped ion mobility separation (TIMS) devices (e.g., U.S. Pat. No. 7,838,826 and U.S. Pat. No. 9,683,964) and field asymmetric ion mobility separation (FAIMS) devices (e.g., U.S. Pat. No. 7,223,967; U.S. Pat. No. 10,325,767 and references cited therein)—are often used as "front-end" devices for pre-processing ion streams prior to their introduction into a mass spectrometer. The inclusion of such an ion mobility separation device between the ion source and the mass analyzer provides a separate mode of ion species separation, the results of which are different from the species separation according to the m / z provided by the mass analyzer. Thus, ion mobility pre-processing can separate the ion species of interest from interfering ion species in space and / or time, which interfering ion species would otherwise not be resolved from each other by mass analysis alone.

[0099] System 130 includes an ion mobility separation device 132 that receives an ion flow 131 from an ion source (not shown). The ion flow 131 includes ions of multiple ion species, each species having a corresponding m / z value and a corresponding ion mobility property. Ions from the incident ion flow 131 are periodically accumulated into discrete packets in the upstream capture portion of the IMS device 132 or in a separate ion trap (not shown) inserted between the ion source and the device 132. Each ion packet includes all ion species of the original ion flow. Periodically, the ion packet is released individually into the mobility separation region of the IMS device 132. The ions of each ion species in each packet migrate through the IMS device according to the migration properties of the ion species. Therefore, the ion species become separated from each other at least spatially during migration through the IMS device 132. Therefore, the ions from each packet appear as a new ion flow 133 from the outlet of the IMS device, and the new ion flow includes a quasi-continuous classification of ion species (depicted by a gradient dot pattern), wherein the most mobile ions appear first, and the least mobile ions appear last.

[0100] Still refer to Fig. 6A According to the teachings of the present invention, ions in the fractionated ion flow 133 are generally driven into the ion transfer device 134 by a potential gradient applied between the IMS device 132 and the ion transfer device 134. It should be noted that other ion optical components such as ion lenses and ion gates may be positioned between the IMS device and the transfer device and elsewhere within the system 130. For the sake of clarity and simplicity, such ion optical components are not shown in FIG. Fig. 6A134. In the ion transfer device 134, the ions in the quasi-continuous graded ion flow 133 are accumulated and bunched into new discrete ion packets using the method described above or a method similar thereto. Each new ion packet contains ion species, which include ion mobility properties of a limited range, and the ion mobility properties are different between packets. One such packet 135 is indicated to be transferred in the ion transfer device. Another packet 137 including ion mobility properties different from the ion mobility properties of packet 135 (as indicated by the different dot patterns of the packet) is shown after leaving the ion transmission device 134 and transferring to a mass spectrometer or mass analyzer 136.

[0101] The delivery of each ion packet through the ion transfer device is referred to as a separate transfer channel in this article. More than one transfer channel can be active at any time, wherein each transfer channel is operated in a cycle, and each cycle includes a build-up and transfer period of duration t1, t2, etc., as described above. Depending on the intensity of the ion signal from the IMS separation device, the accumulation phase can have a variable duration. For example, the duration of ion accumulation and transfer can be from tens of microseconds to tens of milliseconds, specifically depending on the experimental requirements.

[0102] Figure 6B is a schematic depiction of a second mass spectrometer system 300 in accordance with the teachings of the present invention. The mass spectrometer system includes an ion transfer device array 316 in accordance with the teachings of the present invention, similar to the channel array described in commonly owned US Patent No. 9,607,817, which is incorporated herein by reference in its entirety. Figure 6C is an enlarged view of array 316 showing an example of five ion tunnel devices 20a-20e, each of which can be as shown. Figure 2A Although array 316 is shown as being comprised of ion tunnel devices, any of the other types of ion transport devices discussed herein, or variations thereof, may replace any number or all of the ion tunnel devices.

[0103] The system 300 may include an ion mobility cell 302, which is composed of an area such as a substantially rectangular area, wherein a gas flow 304 moves from a gas inlet 306 at one end to a gas outlet 308 at an opposite end in a first direction. In addition, an electric field gradient 310 may be applied in a second direction. In various embodiments, the first direction and the second direction may form an angle between about 45 degrees and 135 degrees, such as an angle between about 70 degrees and about 110 degrees. In a particular embodiment, the first direction and the second direction may be orthogonal (at right angles, perpendicular) to each other. The gas pressure within the ion mobility cell 302 may be between about 1 Torr and about 20 Torr, such as between about 3 Torr and about 6 Torr.

[0104] The ion source 312 can be positioned at the proximal end of the ion inlet 314 of the ion mobility unit 302, and the ion transfer device array 316 can be positioned at the proximal end of the array of the ion outlet holes 318 of the ion mobility unit. The ion outlet holes 318 can be positioned opposite the ion inlet 314 in the second direction, and can be offset from the ion inlet 314 and spaced apart from each other in the first direction. The ions 320a to 320e entering the mobility unit 302 from the ion source 312 can be separated into the ion outlet holes 318 and guided into the ion transfer device array 316 according to their ion mobility in the mobility unit 302. In various embodiments, the ions 320a to 320e can flow at substantially the same speed along the first direction, and can move in the second direction according to their collision cross section. Therefore, relative to the ions 320a with a smaller collision cross section, the ions 320e with a larger collision cross section may move more slowly in the second direction due to the larger number of collisions with the molecules in the gas flow. Because ion 320e moves more slowly in the second direction, it moves farther in the first direction during its traversal of mobility cell 302. In this way, ions with increasingly larger collision cross sections can be sorted into ion transfer device array 316 such that the ion mobility range of ions in an ion transfer device is different from the ion mobility range of ions in an adjacent ion transfer device.

[0105] A cooling / transfer guide 322 may be positioned adjacent to the ion transfer device array 316. Ions may be ejected from any one of the ion transfer devices (e.g., one of the five devices 20a-20e) into the ion cooling / transfer guide 322. Ions may be ejected from only one of the ion transfer devices at any one time, alternatively, may be ejected simultaneously from more than one of the ion transfer devices at one time. Ions from the ion cooling / transfer guide 322 may be directed to a mass analyzer 324. In various embodiments, the ions may be directed to other processes or components, such as a fragmentation unit (not shown), before being directed to the mass analyzer.

[0106] Figure 6C 316 is an enlarged view of an array 316 of ion transport devices 20a-20e. Each such ion transport device includes a corresponding exit gate electrode (i.e., one of the exit gate electrodes 13a-13e in the illustrated example). As illustrated, each exit gate electrode can be separated from its associated ion tunnel. However, in some cases, the exit gate electrode can be a specific ring-shaped or plate-shaped electrode of the ion tunnel that is electrically configured to be supplied with a unique potential that can stop ion flow at certain controlled times and to be supplied with a potential that allows ion flow at certain other times. Further, one or more of the ion transport devices 20a-20e may include an internal gate electrode ( Figure 6B-6C The internal gate electrode is disposed between the ion inlet and the ion outlet of the device and is similar to Figure 3A Similar to the exit gate electrode, the internal gate electrode may be separated from the ion tunnel structure, or alternatively, may be one of the plate electrodes or ring electrodes of the ion tunnel structure.

[0107] The ion transfer array 316 of system 300 can spatially separate ions to allow only one or a few types of ions to be directed to the mass analyzer at a time, while capturing multiple groups of ions that can be stored in a trap and subsequently injected into the mass analyzer. Ejection from the ion transfer devices can allow the mass analyzer to mass analyze ion packets ejected from a selected one or a selected subset of ion transfer devices 20a-20e, while other ions continue to accumulate and be stored in other ion transfer devices.

[0108] Preferably, the individual ion transport devices in array 316 can be operated in parallel and can be controlled independently of one another. The provision of an array of parallel, independently operated ion transport devices allows the trapped ion content of some of the ion transport devices to be selectively injected into mass analyzer 324 (via ion cooling / transfer guide 322) while other ions are accumulated. Exit gate electrodes 13a-13e are used to control which ion packets are released to the mass analyzer at any particular time. Further, using the above reference Figures 4A-4D 5A-5B, each ion transfer device can accumulate and temporarily capture at least one ion packet while simultaneously releasing earlier accumulated ion packets to the ion cooling / transfer guide 322. The cycle times of the various ion transfer devices may not be exactly the same. Different predetermined cycle times can be used to accumulate different ion species over time periods that are inversely proportional to their relative abundance in the sample.

[0109] Figure 6BThe mass spectrometer system 300 depicted in is only an example of a mass spectrometer system, wherein the ion transmission device according to the teachings of the present invention can be arranged along the ion path between the ion source and the mass analyzer, wherein the ion path is straight, curved or even tortuous. According to a more generalized version of system 300, the mobility unit 302 can be replaced by any device that provides an ion flow, and the composition of the ion flow varies over time. For example, the device can be composed of a simple ion source such as electrospray, thermal spray, paper spray or atmospheric pressure chemical ion source that receives a material flow, and the chemical composition of the ion source varies over time. The material flow can be provided by, for example, a chromatographic column or other chemical fractionation equipment coupled to the ion source. Alternatively, the device providing the ion flow can include a mass filter. An ion switch device (not shown) can be inserted between the device providing the ion flow and the ion transmission device array 316. The ion switch can be operated so that different parts of the ion flow are directed to different individual ion transmission devices and accumulated therein.

[0110] In another general version of system 300, separator 302 can be based on a principle different from the ion mobility in the gas. For example, separation can be completed based on ion m / z or charge state. The separation mechanism may be due to competition of forces acting on ions, which is known in the art to be m / z or z-related. One such example involves the effect of pseudo-forces that appear in a non-uniform periodic electric field, such as described in U.S. Patent No. 10,510,525. Separation in units of m / z may be significantly rougher than the separation of a mass analyzer, but it may be useful if ions are separated by fractions in time or space. These fractions can be captured in separate channels and analyzed in sequence without exceeding the capacity of the mass analyzer, thereby increasing selectivity. The analysis duty cycle is enhanced because the accumulation in the capture trap is continuous for multiple fractions, and only one of them is delivered to the mass analyzer.

[0111] The methods and apparatus described herein allow for mass analysis of multiple individual ion fractions while maintaining high speed of ion transport without loss of duty cycle and without resorting to large voltages at the end of the optical path. Due to the relationship between the axial potential distribution segments, any desired number of ions can be transferred to the mass spectrometer without the need for large voltage gradients, controlled gas flows, or special dynamic voltage arrangements such as traveling waves. This simplifies the mechanical design and electronics required to drive the device. The operation of the ion transfer apparatus discussed herein requires a certain amount of background gas pressure. This is because, without collision cooling promoted by the background gas, it is difficult to confine ions with initial kinetic energy to a specific location in the apparatus. Nevertheless, the available pressure range is wide, for example from a few millitorr to tens of torr.

[0112] Any patent, patent application, patent application publication, or other document mentioned herein is incorporated by reference in its respective entirety as if fully set forth herein, except that in the event of any conflict between an incorporated reference and the present specification, the language of the present specification controls.

Claims

1. A mass spectrometer system, comprising: Ion source; Mass analyzer; an ion transmission device disposed along an ion path between the ion source and the mass analyzer, the ion transmission device comprising: an ion inlet having an inlet electrode at the ion inlet and disposed at a longitudinal position X0; An ion outlet having an exit electrode at the ion outlet and arranged at a longitudinal position X L and a plurality of annular or plate-shaped electrodes, the plurality of annular or plate-shaped electrodes being disposed between the inlet electrode and the outlet electrode; one or more power supplies electrically coupled to the inlet electrode and the outlet electrode and to the plurality of ring or plate electrodes; and A computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to: supplying an oscillating radio frequency (RF) voltage to each of the plurality of ring or plate electrodes, wherein the RF phase supplied to each electrode is out of phase by π radians relative to the RF phase supplied to each adjacent electrode; and Repeat the following steps: (a) providing a corresponding first direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes for a duration, wherein the plurality of first direct current (DC) voltages define a first potential distribution, wherein the first potential distribution is at a longitudinal position X. k The ion trapping potential well is defined at X0 <X k <X L ;as well as (b) providing a corresponding second direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes for a duration, the plurality of second direct current (DC) voltages defining a second potential distribution, the second potential distribution at position X k The axial field is established at the longitudinal position X, and the axial field is directed to push the ions toward the exit electrode, and the plurality of the second direct current (DC) voltages are further provided at the longitudinal position X. i The trapping potential well is defined at <X i <X k .

2. The mass spectrometer system of claim 1 , wherein the first potential distribution comprises: Position X0 and position X k The generally descending distribution section between the positions X0 and X1 is operable to move away from the position X0 and toward the position X2. k Propels positively charged ions; as well as Position X k With position X L A generally ascending distribution section between the positions X and X, the generally ascending distribution section being operable to move away from the position X L and towards position X k Propels positively charged ions.

3. The mass spectrometer system of claim 1 , wherein the first potential distribution comprises: Position X0 and position X k The generally ascending distribution section between the positions X0 and X1 is operable to move away from the position X0 and toward the position X2. k Propel negatively charged ions; as well as Position X k With position X L A generally descending distribution section between the positions X and X, the generally descending distribution section being operable to move away from the position X L and towards position X k Promotes negatively charged ions.

4. A mass spectrometer system according to claim 1, wherein the computer-readable instructions that are operable to cause the one or more power supplies to repeatedly perform the step (a) of providing a corresponding first direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes are operable to cause the providing to occur for a duration τ1 that depends on one or both of the group consisting of: the flux of ions delivered to the inlet of the ion transmission device and the gas pressure within the ion transmission device.

5. A mass spectrometer system according to claim 1, wherein the computer-readable instructions that are operable to cause the one or more power supplies to repeatedly perform step (b) of providing a corresponding second direct current (DC) voltage to each of the multiple annular or plate-shaped electrodes are operable to cause the provision to occur for a second duration τ2, where τ2<τ1.

6. The mass spectrometer system of claim 1, wherein the gas pressure within the ion transmission device is greater than 1 mTorr.

7. The mass spectrometer system of claim 1, further comprising: An ion mobility separation device is disposed along the ion path between the ion source and the ion transport apparatus.

8. The mass spectrometer system according to claim 5, wherein the ion outlet comprises a gate electrode; and The computer-readable instructions operable to cause the one or more power supplies to repeatedly perform step (b) of providing a corresponding second direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes are further operable to cause the gate electrode to remain in a closed configuration for a first portion of the second duration τ2.

9. The mass spectrometer system of claim 1, further comprising: An ion separation device is disposed along the ion path between the ion source and the ion transport device, wherein the ion separation device is configured to separate the ion species according to their respective charge states z or according to their respective mass-to-charge ratios m / z.

10. The mass spectrometer system of claim 9, wherein the ion separation device is configured to separate ion species under the influence of a pseudo-force generated by a non-uniform periodic electric field.

11. The mass spectrometer system of claim 1 , wherein the ion transmission device is one of a plurality of similar ion transmission devices disposed along the ion path between the ion source and the mass analyzer and electrically coupled to the one or more power supplies.

12. A mass spectrometer system comprising: Ion source; Mass analyzer; an ion transmission device disposed along an ion path between the ion source and the mass analyzer, the ion transmission device comprising: an ion inlet having an inlet electrode at the ion inlet and disposed at a longitudinal position X0; An ion outlet having an exit electrode at the ion outlet and arranged at a longitudinal position X L and A plurality of multipolar sections, the plurality of multipolar sections being disposed between the inlet electrode and the outlet electrode, each multipolar section comprising a plurality of rod electrodes correspondingly arranged parallel to each other; one or more power supplies electrically coupled to the entrance electrode and the exit electrode and to the plurality of rod electrodes of each multipolar section; and A computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to: supplying an oscillating radio frequency (RF) voltage to each rod electrode of each multipolar segment, wherein within each multipolar segment, the RF phase supplied to each rod electrode of the segment is out of phase by π radians relative to the RF phase supplied to each adjacent rod electrode of the segment; and Repeat the following steps: (a) providing a corresponding first direct current (DC) voltage to all rod electrodes of each multipolar segment of the plurality of multipolar segments for a duration, the plurality of first direct current (DC) voltages defining a first potential distribution, the first potential distribution at the longitudinal position X k The ion trapping potential well is defined at X0 <X k <X L ;as well as (b) providing a corresponding second direct current (DC) voltage to all rod electrodes of each multipolar segment of the plurality of multipolar segments for a duration, the plurality of second direct current (DC) voltages defining a second potential distribution, the second potential distribution at position X k The axial field is established at the longitudinal position X, and the axial field is directed to push the ions toward the exit electrode, and the plurality of the second direct current (DC) voltages are further provided at the longitudinal position X. i The trapping potential well is defined at <X i <X k .

13. The mass spectrometer system of claim 12, wherein the first potential distribution comprises: Position X0 and position X k The generally descending distribution section between the positions X0 and X1 is operable to move away from the position X0 and toward the position X2. k Propels positively charged ions; as well as Position X k With position X L A generally ascending distribution section between the positions X and X, the generally ascending distribution section being operable to move away from the position X L and towards position X k Propels positively charged ions.

14. The mass spectrometer system of claim 12, wherein the first potential distribution comprises: Position X0 and position X k The generally ascending distribution section between the positions X0 and X1 is operable to move away from the position X0 and toward the position X2. k Propel negatively charged ions; as well as Position X k With position X L A generally descending distribution section between the positions X and X, the generally descending distribution section being operable to move away from the position X L and towards position X k Promotes negatively charged ions.

15. A mass spectrometer system according to claim 12, wherein the computer-readable instructions that are operable to cause the one or more power supplies to repeatedly perform step (a) of providing a corresponding first direct current (DC) voltage to all rod electrodes of each of the plurality of multipole segments are operable to cause the providing to occur for a duration τ1 that depends on one or both of the group consisting of: the flux of ions delivered to the inlet of the ion transfer device and the gas pressure within the ion transfer device.

16. A mass spectrometer system according to claim 12, wherein the computer-readable instructions that are operable to cause the one or more power supplies to repeatedly perform step (b) of providing a corresponding second direct current (DC) voltage to all rod electrodes of each of the plurality of multipole segments are operable to cause the providing to occur for a second duration τ2, wherein τ2<τ1.

17. The mass spectrometer system of claim 12, wherein the gas pressure within the ion transmission device is greater than 1 mTorr.

18. The mass spectrometer system of claim 12, further comprising: An ion mobility separation device is disposed along the ion path between the ion source and the ion transport apparatus.

19. The mass spectrometer system of claim 12, wherein the ion transmission device is one of a plurality of similar ion transmission devices disposed along the ion path between the ion source and the mass analyzer and electrically coupled to the one or more power supplies.

20. The mass spectrometer system of claim 12, further comprising: An ion separation device is disposed along the ion path between the ion source and the ion transport device, wherein the ion separation device is configured to separate the ion species according to their respective charge states z or according to their respective mass-to-charge ratios m / z.

21. The mass spectrometer system of claim 20, wherein the ion separation device is configured to separate ion species under the influence of a pseudo-force generated by a non-uniform periodic electric field.

22. A method of transporting ions within a mass spectrometer, the method comprising: receiving a continuous flow of positively charged ions at an inlet end of an ion transport device, the ion transport device further comprising an outlet end; generating a first potential profile within the ion transport device for a duration, the first potential profile causing a first portion of the ion flow to accumulate at a first potential well within the ion transport device at a first location between the inlet end and the outlet end, the accumulation being driven by a potential difference between the first location and the inlet end; generating a second potential profile within the ion transport device for a duration, the second potential profile establishing an axial field at the first location, the axial field being directed to urge ions toward the outlet end, and simultaneously generating a second potential well at a second location within the ion transport device, the second location being disposed between the first location and the inlet end; as well as The accumulated first part of the ion flow is transported from the first position to the outlet end under the impetus of the axial field, and the second part of the ion flow is simultaneously accumulated at the second potential well, wherein the accumulation of the second part of the ion flow is driven by the potential difference between the second position and the inlet end.

23. The method of transporting ions within a mass spectrometer of claim 22, wherein an inlet potential at the inlet end and an outlet potential at the outlet end are both constant, and wherein the outlet potential is greater than the inlet potential.

24. A method for transmitting ions within a mass spectrometer according to claim 22, wherein the first potential well is maintained for a duration τ1 that depends on one or both of the group consisting of: the flux of ions delivered to the inlet of the ion transmission device and the gas pressure within the ion transmission device.

25. The method of transporting ions within a mass spectrometer of claim 22, wherein the step of transporting the accumulated first portion of the ion flow from the first location to the outlet comprises: bunching the first portion of the ion flow into ion packets at an exit gate electrode, the exit gate electrode being maintained in a closed configuration that blocks ions from passing through the exit gate; and The exit door is reconfigured to an open position allowing the ion packets to exit the ion transport device through the exit end of the ion transport device.

26. The method of transmitting ions within a mass spectrometer according to claim 22, further comprising: generating a third potential profile within the ion transport device to establish a third potential well at the first location and continuing to cause the second portion of the ion flow to accumulate at the third potential well, the accumulation being driven by a potential difference between the first location and the inlet end; generating a fourth potential profile within the ion transport device to establish a second axial field at the first location, the second axial field being directed to urge ions toward the outlet end, and the fourth potential profile simultaneously generating a fourth potential well at the second location; as well as Under the impetus of the second axial field, the accumulated second part of the ion flow is transmitted from the first position to the outlet end, and at the same time, a third part of the ion flow is accumulated at the fourth potential well, and the accumulation of the third part of the ion flow is driven by the potential difference between the second position and the inlet end.

27. The method of transmitting ions within a mass spectrometer of claim 22, wherein said receiving said continuous stream of positively charged ions comprises receiving a continuous stream of ions from an ion mobility separation device.

28. A system for analyzing a sample, the system comprising: an ion source configured to generate ions from constituent components of the sample; a mobility separator configured to separate the ions received from the ion source based on their respective mobilities in a gas, the mobility separator providing a gas flow in a first direction and an electric field gradient in a second direction so that the ions move in the first direction and drift according to the mobility of the ions in the second direction so that the ions are classified according to their respective mobilities; a plurality of ion transfer devices arranged adjacent to the mobility separator such that ions from the mobility separator are directed to different ion transfer devices according to respective mobilities of the ions, each ion transfer device comprising: an exit ion gate operable to release ions from the ion transport device through an outlet of the ion transport device or to prevent ions from being released from the ion transport device through an ion outlet of the ion transport device; a mass analyzer configured to receive ions from the ion outlet of each ion transmission device; and one or more power supplies electrically coupled to the mobility separator and the plurality of ion transport devices; and A computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to: For each ion transmission device in the plurality of ion transmission devices: supplying an oscillating radio frequency (RF) voltage to each of a plurality of annular or plate electrodes of the ion transport device disposed between an inlet and an outlet of the ion transport device, wherein a phase of the RF supplied to each electrode is out of phase by π radians relative to a phase of the RF supplied to each adjacent electrode; and Repeat the following steps: (a) providing a corresponding first direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes for a duration, wherein the plurality of first direct current (DC) voltages define a first potential distribution, wherein the first potential distribution is at a longitudinal position X. k The ion trapping potential well is defined at X0 <X k <X L ;as well as (b) providing a corresponding second direct current (DC) voltage to each of the plurality of annular or plate-shaped electrodes for a duration, the plurality of second direct current (DC) voltages defining a second potential distribution, the second potential distribution at position X k The axial field is established at the longitudinal position X, and the axial field is directed to push the ions toward the outlet. The plurality of the second direct current (DC) voltages are further provided at the longitudinal position X. i The trapping potential well is defined at <X i <X k .

29. The system for analyzing a sample according to claim 28, further comprising: A computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to operate the plurality of exit ion gates of the plurality of ion transmission devices such that ions are released from one or more of the plurality of exit ion gates at any one time.

30. The system for analyzing a sample according to claim 28, further comprising: a computer or electronic controller electrically coupled to the one or more power supplies and comprising computer readable instructions operable to cause the one or more power supplies to: operate the plurality of exit ion gates of the plurality of ion transmission devices such that ions received from the mobility separator accumulate in each ion transmission device for a respective accumulation duration, wherein the plurality of accumulation durations are not identical.

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