Apparatus and method for ion injection in mass spectrometry

Abstract

In some examples, the apparatus may include an ion injector with an ion injector inlet and an ion injector outlet, and a capillary cap positioned at the ion injector outlet. The capillary cap may include a capillary cap outlet opening that is shaped and sized to reduce gas turbulence after the ion injector outlet and improve ion signal stability.

Description

Technical Field

[0001] The present invention relates to an apparatus and method for ion incidence in mass spectrometry.

Background Art

[0002] In some cases, ionization methods in mass spectrometry (MS) operate at atmospheric pressure. Ions generated at atmospheric pressure can be transported from atmospheric pressure to the vacuum region of an MS system in order to detect ionized species by an atmospheric pressure (AP) ion source and measure their mass-to-charge ratio. In some cases, the MS system can generally include an ion injector, an electrodynamic ion funnel, and an ion desolvation component.

[0003] The features of the present disclosure are illustrated by way of example and are not limited to the following figures in which like numerals represent like elements.

Brief Description of the Drawings

[0004] [Figure 1] An atmospheric pressure-vacuum interface is illustrated according to an example of the present disclosure. [Figure 2] A single-hole resistive glass capillary (hereinafter also referred to as an "ion injector") is illustrated according to an example of the present disclosure. [Figure 3] A round capillary cap and a slot outlet capillary cap are illustrated according to an example of the present disclosure. [Figure 4] Examples of slot, cross, star, and muzzle brake-shaped outlet capillary caps are illustrated according to an example of the present disclosure. [Figure 5] Various views of a slot outlet capillary cap are illustrated according to an example of the present disclosure. [Figure 6] A cross-sectional view of a first portion of a muzzle brake-shaped outlet capillary cap is illustrated according to an example of the present disclosure. [Figure 7] Various views of a second portion of a muzzle brake-shaped outlet capillary cap are illustrated according to an example of the present disclosure. [Figure 8] In accordance with an example of this disclosure, various diagrams are illustrated, including a cross-sectional view of an ion injector with an inlet round hole and a slotted outlet capillary cap. [Figure 9] In accordance with an example of this disclosure, various diagrams are provided, including a cross-sectional view of an ion injector with an inlet round hole, a muzzle outlet capillary cap, and an inlet cap. [Figure 10] An example of this disclosure illustrates the stability of a multiple reaction ion monitoring (MRM) ion signal without applying a smoothing function to the ion signal. [Figure 11A] In accordance with an example of this disclosure, Figure 5 illustrates a cross-section of an ion desolvation component including an ion funnel and an atmospheric pressure vacuum interface, along with the slot outlet capillary cap and ion injector. [Figure 11B] In accordance with an example of this disclosure, another example of a cross-section of the slot cap and ion desolvation component in Figure 5, including the inlet cap, is illustrated. [Figure 12] In accordance with an example of this disclosure, the cross-sectional area of ​​a single-hole (SB) capillary (hereinafter also referred to as an "ion injector") and various outlet cap shapes sorted based on the cross-sectional area are illustrated. [Figure 13] An example of this disclosure illustrates ion funnel pressures at various outlet cap shapes and sizes, as well as the decrease in ion funnel pressure as an indicator of gas flow restriction. [Figure 14] In accordance with an example of this disclosure, principal component analysis (PCA) score plots obtained from ion signal relative standard deviation (RSD) analysis of various rotation angles of the slot outlet capillary cap relative to the ion injector axis are illustrated. [Figure 15] In accordance with an example of this disclosure, PCA score plots obtained from ion signal RSD analysis with various inlet configurations are illustrated. [Figure 16] In accordance with an example of this disclosure, liquid chromatography-mass spectrometry (LC / MS / MS) MRM chromatograph peak area versus RSD obtained for a pesticide mixture is illustrated. [Modes for carrying out the invention]

[0005] For the sake of brevity and illustrative purposes, this disclosure is written primarily by reference to examples. Numerous specific details are given in the following description to provide a complete understanding of this disclosure. However, it will immediately become clear that this disclosure may be implemented without being limited to these specific details. In other instances, some methods and structures are not described in detail to avoid unnecessarily obscuring this disclosure.

[0006] Throughout this disclosure, the terms “a” and “an” are intended to indicate at least one of the particular elements. As used herein, the term “including” means including but not limited to these, and the term “containing” means including but not limited to these. The term “based on” means at least in part on. The term “inlet” refers to the inlet end of the ion injector through which gas molecules and ions enter the ion injector from the ion source. The term “outlet” refers to the outlet end of the ion injector through which gas molecules and ions exit the ion injector toward the MS.

[0007] Apparatus for ion injection in mass spectrometry (MS) and methods for ion injection in MS are disclosed herein.

[0008] With respect to the apparatus and methods disclosed herein, the ionization method in the MS operates at atmospheric pressure, as disclosed herein. To achieve the highest possible sensitivity with an atmospheric pressure (AP) ion source, ions generated at atmospheric pressure may be transported from atmospheric pressure to the vacuum region of the MS system, for example, using a round-hole ion injector capillary or aperture. Generally, these ion injector capillaries and apertures may be isolated from the main vacuum stage of the MS by conductance limiting, as well as by differentially pumped ion optics and interfaces.

[0009] In some examples, high gas flows into MS systems and one of the atmospheric pressure vacuum interfaces used involves an electrodynamic ion funnel. One advantage of an ion funnel interface is its ability for efficient ion collection and guidance.

[0010] With respect to atmospheric pressure vacuum interfaces, the ion flux may be increased by using wider-hole ion injector capillaries to enhance sensitivity to MS systems equipped with ion funnels. In this regard, utilizing wider-hole capillaries may present technical challenges in controlling the neutral gas flow to the ion funnel for more efficient pumping and a stable ion beam.

[0011] To address the aforementioned technical challenges, in some cases, ion injectors with long slots may be used with an ion funnel interface to achieve higher ion flux and improved pumping efficiency in the MS system. However, ion signal stability may not be addressed with such ion injectors. Furthermore, the manufacturing process for machining such ion injectors may present technical challenges.

[0012] Apparatus and methods disclosed herein address the aforementioned technical challenges by achieving ion injection from atmospheric pressure into the vacuum of an MS system using a round-hole capillary (e.g., an "ion injector" as disclosed herein). In one example, the ion injector may include a slotted capillary cap with an inner diameter of 1.2 mm, a length of 90 mm, and a width of 0.6 mm. Other ion injectors with cross, star, and muzzle-brake shaped capillary capillaries, in addition to those with different slot widths, may also be utilized with different capillary inner diameters.

[0013] The devices and methods disclosed herein are provided for reducing gas turbulence and recirculation at the atmospheric vacuum interface such as an ion funnel. This leads to improved ion signal reproducibility and accuracy, and thus lower MS detection limits.

[0014] For the devices and methods disclosed herein, the outlet capillary cap may be manufactured separately from the ion injector and thus provide a desired outlet pattern that inhibits the neutral gas jet entering the ion funnel.

[0015] According to an example disclosed herein, the device may include an ion injector including an ion injector inlet and an ion injector outlet, and a capillary cap disposed at the ion injector outlet. The capillary cap may include a capillary cap outlet opening shaped and sized to reduce gas turbulence (e.g., in an ion funnel) after the ion injector outlet and improve ion signal stability.

[0016] In some examples, the capillary cap outlet opening may include a rectangular slot shape. In this regard, the rectangular slot shape may include a curved portion. Alternatively, the capillary cap outlet opening may include a cross slot shape, a star slot shape, or a muzzle brake configuration including a circular capillary cap outlet opening and an elongated slot along the sidewall of the capillary cap. The capillary cap may include a concave area on the opposite side of the outlet face of the capillary cap.

[0017] According to an example disclosed herein, the capillary cap may be disposed at the ion injector outlet of an ion injector including an ion injector inlet and an ion injector outlet. The capillary cap may include a capillary cap outlet opening shaped and sized to reduce gas turbulence (e.g., in an ion funnel) after the ion injector outlet and improve ion signal stability.

[0018] According to an example disclosed herein, the method may include attaching a capillary cap to an ion injector that includes an ion injector inlet and an ion injector outlet. The capillary cap may include a capillary cap outlet opening that is shaped and sized to reduce gas turbulence (e.g., in an ion funnel) after the ion injector outlet and improve ion signal stability.

[0019] FIG. 1 illustrates an atmospheric pressure vacuum interface 100 according to an example of the present disclosure.

[0020] Referring to FIG. 1, the atmospheric pressure vacuum interface 100 may include an ion injector 102 that includes an inlet capillary cap 104 and an outlet capillary cap 106. The atmospheric pressure vacuum interface 100 may further include an ion funnel 108, and the pressure region of the atmospheric pressure vacuum interface 100 is separated into an atmospheric pressure region 110, a low vacuum region 112, and a high vacuum region 114 using differential pumping.

[0021] FIG. 2 illustrates a single-hole resistive glass capillary (hereinafter also referred to as an “ion injector”) according to an example of the present disclosure.

[0022] Referring to FIG. 2, FIGS. including an end view, a side view, a cross-sectional view, and an enlarged cross-sectional view are shown at 200, 202, 204, and 206, respectively. In the illustrated example, the ion injector 102 may include a hole 220 having an inner diameter of 1.2 mm as shown at 208 and a length of 90 mm as shown at 210. Additionally, various additional dimensions are shown for the example of FIG. 2. However, other ion injectors with different dimensions may also be utilized with different capillary inner diameters as needed. Firing may be applied to the range 212 to smooth the ground surface and make the sharp edges less prominent. Both ends of the ion injector 102 may be plated as shown at 214, and the resistive surface is removed at 216.

[0023] Figure 3 illustrates a round capillary cap and a slotted outlet capillary cap according to an example of the present disclosure.

[0024] Referring to Figure 3, a round capillary cap 300 is shown, which includes, for example, an inlet inner diameter (ID) of 4.2 mm. However, other IDs may be used for the round capillary cap 300 as needed. Furthermore, a rectangular slot outlet capillary cap 302 is shown, which includes, for example, a slot length of 4.0 mm and, for example, a slot width of 0.6 mm. However, other slot lengths and widths may be used for the rectangular slot outlet capillary cap 302 as needed. In the example of Figure 3, the rectangular slot may include a curved portion as indicated by 304. The configuration of the rectangular slot outlet capillary cap 302 as shown may obstruct the gas flowing through the constant-diameter ion injector 102 and exiting the rectangular slot outlet capillary cap 302.

[0025] The round capillary cap 300 may be used at both the inlet and outlet of the ion injector. However, as disclosed herein, a slotted (or otherwise shaped) capillary cap may be used at the outlet of the ion injector, thereby potentially providing a more stable ion signal compared to using a round capillary cap. One example of an ion injector configuration may include a round-hole inlet capillary cap, a single-hole ion injector, and a round-hole outlet capillary cap. Another example of an ion injector configuration may include a round-hole inlet capillary cap, a single-hole ion injector, and a molded (e.g., slotted, cross, star-shaped, or muzzle brake) outlet capillary cap, thereby potentially improving ion signal stability as disclosed herein.

[0026] Figure 4 illustrates examples of slotted, cross-shaped, star-shaped, and muzzle brake-shaped outlet capillary caps in accordance with an example of the present disclosure.

[0027] Referring to Figure 4, and in comparison to the example in Figure 3, rectangular slot outlet capillaries are shown in 400 and 402, including different slot widths, for example, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, and 0.8 mm. A cross outlet capillary is shown in 404, a star-shaped outlet capillary is shown in 406, and a muzzle brake-shaped outlet capillary is shown in 408. The cross outlet capillary shown in 404 may include two orthogonal slots, as shown in 410. The star-shaped outlet capillary is shown in 406 may include three slots arranged in a star pattern, as shown in 412. Furthermore, the muzzle brake-shaped outlet capillary is shown in 408 may include first and second parts 418 and 420, respectively. The first part 418 is illustrated in more detail in Figure 6. The second portion 420 is shown in more detail in Figure 7 and may include a circular capillary outlet opening 414 and an extension slot 416 along the side wall of the capillary cap. In this respect, the gas may exit through the extension slot 416 in addition to the circular capillary outlet opening 414.

[0028] Figure 5 illustrates various diagrams of a slot exit capillary cap according to an example of this disclosure.

[0029] Referring to Figure 5, another example of the rectangular slot outlet capillary cap 500 is illustrated. In this regard, various views, including top, front, side, bottom, and isometric views, are shown in 502, 504, 506, 508, and 510, respectively. The rectangular slot outlet capillary cap 500 may include a concave region 512 opposite the outlet surface 514 of the capillary cap. Referring to Figures 2 and 5, the concave region 512 may provide a gap between the outlet surface 218 of the ion injector 102 and the inner region 516 of the capillary cap. In this regard, the slot 520 of the rectangular slot outlet capillary cap 500, which may include dimensions in the range of 0.3 mm to 0.8 mm, can partially cover the hole 220, which may include dimensions of about 1.2 mm, so that the gap provided by the concave range 512 can allow for unblocked flow of gas through the hole 220 of the ion injector 102, further through the concave range 512, and out of the slot 520. In other examples, the slot 520 of the rectangular slot outlet capillary cap 500 may include a width dimension that is greater than or equal to the diameter of the hole 220. Furthermore, the rectangular slot outlet capillary cap 500 may include an opening 518 for providing electrical contact to the ion injector 102, for example, via an angled coil spring.

[0030] In some examples, the slot 520 of the rectangular slot outlet capillary cap 500 (and other slots and outlet openings as otherwise disclosed herein) may be centrally located along the central longitudinal axis of the hole 220 of the ion injector 102. In other examples, the slot 520 of the rectangular slot outlet capillary cap 500 (and other slots and outlet openings as otherwise disclosed herein) may be radially offset with respect to the central longitudinal axis of the hole 220 of the ion injector 102. In other examples, as shown in Figure 1, the ion injector 102 may be positioned radially offset with respect to the central longitudinal axis 116 of the ion funnel 118. This offset minimizes the possibility of large droplets exiting the ion injector 102, traveling in a straight line through the ion funnel 118, and reaching downstream ion optics, thus minimizing optical system contamination and chemical noise.

[0031] Figure 6 illustrates a cross-section of a first portion of a muzzle brake-shaped outlet capillary cap according to an example of the present disclosure.

[0032] Referring to Figure 6, a cross-sectional view similar to that of cross-section BB in Figure 5 is shown with respect to the first portion 418 of the muzzle brake-shaped outlet capillary cap 408. The first portion 418 of the muzzle brake-shaped outlet capillary cap 408 may include a curved space 602 on the opposite side of the capillary cap surface 604. Referring to Figures 2 and 6, the curved space 602 may provide a gap between the outlet surface 218 of the ion injector 102 and the inner range 606 of the first portion 418. The first portion 418 may include an opening 608 similar to the opening 518 of the rectangular slot outlet capillary cap 500 for providing electrical contact to the ion injector 102 via an angled coil spring. Furthermore, the first portion 418 may include a recessed region 610 on the surface 604.

[0033] Figure 7 illustrates various views of the second portion of a muzzle brake-shaped outlet capillary cap according to an example of the present disclosure.

[0034] Referring to Figures 4 and 7, as disclosed herein, the second portion 420 of the muzzle brake-shaped outlet capillary cap illustrated in 408 may include a circular capillary cap outlet opening 414 and an extension slot 416 along the side wall of the second portion 420. The extension slot 416 may provide a spring force action for gripping the first portion 418 of the muzzle brake-shaped outlet capillary cap illustrated in 408, and an opening for gas release. In this regard, various figures of the second portion 420 are shown, including top, side, and bottom views, as well as first and second isometric views, in 700, 702, 704, 706, and 708, respectively. The second portion 420 may include a recessed area 710 opposite the outlet surface 712. Referring to Figures 6 and 7, the recessed area 710 may provide a gap between the surface 604 (e.g., by the recessed area 610) and the inner area 714 of the second portion 420. Referring to Figures 6, 7, and 9, the first and second portions 418 and 420 are arranged in an engaged configuration, respectively, illustrating the gap 906 defined by the recessed area 610 and the inner area 714. The gap 906 may be further defined by a spacer 716 separating the recessed area 610 and the inner area 714.

[0035] Figure 8 illustrates various diagrams, including a cross-sectional view of an ion injector with an inlet round hole and a slotted outlet capillary cap, according to an example of the present disclosure.

[0036] Referring to Figure 8, an example of the ion injector 102 may include a 1.2 mm inner diameter (ID) capillary with a 2.0 mm ID inlet capillary cap 104. The ion injector 102 may further include an outlet capillary cap 106, which may include a slot outlet capillary cap. The left side, right side, top, two bottom, and isometric views of the ion injector 102 are shown as 800, 802, 804, 806, 808, and 810, respectively.

[0037] Figure 9 illustrates various diagrams, including a cross-sectional view of an ion injector with an inlet round hole, a muzzle outlet capillary cap, and an inlet cap, in accordance with an example of the present disclosure.

[0038] Referring to Figure 9, another example of the ion injector 102 may include a 1.2 mm inner diameter (ID) capillary with a 2.0 mm ID inlet capillary cap 104. The ion injector 102 may further include an outlet capillary cap 106, which may include first and second portions 418 and 420, respectively, of a muzzle brake-shaped outlet capillary cap shown at 408. Left side, isometric, and cross-sectional views of the ion injector 102 are shown at 900, 902, and 904, respectively.

[0039] Figure 10 illustrates the stability of a multiple reaction ion monitoring (MRM) ion signal without applying a smoothing function to the ion signal, according to an example of this disclosure.

[0040] Referring to Figure 10, at 1000, by supplying a constant liquid flow of a constant calibration concentration to an atmospheric pressure (AP) ion source, MRM ion signal stability is exemplified with a residence time of 0.5 ms using a capillary inner diameter (ID) of 1.2 mm, an outlet cap with a round hole (R=4.2 mm), and a slot (W=0.6 mm). MRM ion signal stability is determined without applying smoothing to the ion signal. MRM ion signal stability shows greater stability for the slot outlet capillary cap compared to the round hole outlet capillary cap. In this regard, the characteristic dimensions of the slot outlet capillary cap 302 (e.g., the width of the slot) lead to faster settlement of supersonic expansion compared to the round hole outlet cap, and therefore to a more stable ion signal in the ion funnel downstream of the ion injector 102.

[0041] Figure 11A illustrates a cross-section of an ion desolvation component, including an ion funnel and an atmospheric pressure vacuum interface, along with the slot outlet capillary cap and ion injector shown in Figure 5, in accordance with an example of the present disclosure.

[0042] Referring to Figure 11A, a cross-section of the slot outlet capillary cap and 1.2 mm ion injector in Figure 5 is shown at 1100. An example in Figure 11A further illustrates an ion funnel 1102 and an ion desolvation component 1104 including an atmospheric pressure vacuum interface such as the atmospheric pressure vacuum interface 100 in Figure 1.

[0043] Figure 11B illustrates another example of a cross-section of the slot cap and ion desolvation component of Figure 5, including the inlet cap, in accordance with an example of the present disclosure.

[0044] Referring to Figure 11B, another example of a cross-section of the slot cap of Figure 5, including a 2 mm inner diameter (ID) inlet capillary cap, is shown in 1106. The example in Figure 11B further illustrates the ion desolvation component 1108.

[0045] Figure 12 illustrates, in accordance with an example of the present disclosure, the cross-sectional area of ​​a single-hole (SB) capillary (also referred to herein as an "ion injector") and various outlet cap shapes sorted by cross-sectional area.

[0046] Referring to Figure 12, the cross-sectional areas of SB capillaries and various outlet cap shapes are shown. In this regard, as shown, a slot width (W) = 0.3 mm, where the cross-section is smaller than that of the SB capillary ID = 1.2 mm, restricts gas flow. Ion signal stability can also be improved by reducing the ion funnel pressure by restricting gas flow to the ion funnel or by using a higher pumping capacity. In this regard, the data in Figure 12 shows that all molded outlet capillary caps except for the slot width (W) = 0.3 mm have a cross-sectional area larger than that of the SB capillary ID = 1.2 mm, and do not result in gas flow restriction, nor can improved ion signal stability be achieved if a reduction in ion funnel pressure is considered.

[0047] Figure 13 illustrates, in accordance with an example of this disclosure, the ion funnel pressure at various outlet cap shapes and sizes, as well as the decrease in ion funnel pressure as an indicator of gas flow restriction.

[0048] Referring to Figure 13, the ion funnel pressures using a 1.2 mm ion injector inner diameter (ID) with various outlet cap shapes are shown. In this regard, the table in Figure 13 shows the decrease in ion funnel pressure with respect to slot width (W) = 0.3 mm as an indicator of gas flow limitation. The data in Figure 13 demonstrate that improved ion signal stability can be achieved by using a molded outlet capillary cap (except for slot width (W) = 0.3 mm) or by using a higher pumping capacity, in contrast to a decrease in gas flow.

[0049] Figure 14 illustrates principal component analysis (PCA) score plots obtained from ion signal relative standard deviation (RSD) analysis of various rotation angles of the slot outlet capillary cap relative to the ion injector axis, according to an example of the present disclosure.

[0050] Referring to Figure 14, the PCA score plots obtained from the ion signal RSD analysis of various rotation angles of the slot outlet capillary cap relative to the ion injector axis are shown at 1400. In this case, a negative score indicates an improvement in the ion signal RSD. The main variance of the data is along the PC1 axis. Furthermore, different rotation angles of the slot outlet capillary cap, as shown at 1402, show minimal effect on the ion signal RSD, as shown in the PCA score plot 1400.

[0051] Figure 15 illustrates PCA score plots obtained from ion signal RSD analysis with various inlet configurations, according to an example of this disclosure, where negative scores indicate improvement in ion signal RSD.

[0052] Referring to Figure 15, the PCA score plot obtained from ion signal RSD analysis of various capillary caps installed at the outlet of the ion injector capillary 102 is shown at 1500. In this point, a negative score indicates an improvement in ion signal RSD. Furthermore, different types of capillary caps are shown at 1502. All molded outlet capillary caps outperform the round outlet capillary cap by providing better ion signal RSD at similar ion funnel pressures. Among the molded outlet capillary caps, slotted outlet capillary caps with widths (W) = 0.4 mm, 0.5 mm, 0.6 mm, and 0.7 mm, as well as the cross-shaped outlet capillary cap, achieved better ion signal RSD than slotted outlet capillary caps with widths (W) = 0.8 mm and 0.9 mm, as well as the star-shaped outlet capillary cap.

[0053] Figure 16 illustrates liquid chromatography-mass spectrometry (LC / MS / MS) MRM chromatograph peak area versus RSD obtained for a pesticide mixture according to an example of the present disclosure.

[0054] Referring to Figure 16, the LC / MS / MS MRM chromatographic peak area versus RSD obtained for a pesticide mixture with an extremely short MRM residence time = 0.5 ms is shown as 1600. Residence time may represent the period during which the ion beam is sampled for quantitative measurement. The chromatographic peak area RSD may be determined based on 10 repeated injections of the pesticide mixture, in which the individual pesticides are at equal concentrations. The pesticides in this mixture may encompass a wide range of area reactions (due to their varying ionization efficiencies) corresponding to different numbers of ions reaching the detector. Both short residence times and low chromatographic peak areas can lead to larger RSDs. Using a slotted outlet capillary cap can produce a narrower distribution of peak area RSD for the pesticides in this pesticide mixture compared to a round outlet capillary cap. The improvement in peak area RSD at the outlet of ion injector 102 compared to a slotted outlet capillary cap may indicate that the ion beam entering the ion funnel experiences less variation and noise.

[0055] The information and examples provided herein are examples, as well as some variations thereof. The terms, descriptions, and figures used herein are provided for illustrative purposes only and are not intended to be limiting. While many variations are possible within the spirit and scope of this subject matter, it is intended to be defined by the following claims—and their equivalents—and unless otherwise noted, all terms are intended in their broadest reasonable meaning.

Claims

1. An ion injector including an ion injector inlet and an ion injector outlet, A capillary cap is placed at the outlet of the ion injector, Equipped with, The capillary cap includes a capillary cap outlet opening that is shaped and sized to reduce gas turbulence after the ion injector outlet and improve ion signal stability. Device.

2. The apparatus according to claim 1, wherein the capillary cap includes a concave area on the opposite side of the outlet surface of the capillary cap.

3. The apparatus according to claim 1, wherein the capillary cap outlet opening includes a rectangular slot shape.

4. The apparatus according to claim 3, wherein the rectangular slot shape includes a curved portion.

5. The apparatus according to claim 1, wherein the capillary cap outlet opening includes a cross-slot shape.

6. The apparatus according to claim 1, wherein the capillary cap outlet opening includes a star-shaped slot.

7. The apparatus according to claim 1, wherein the capillary cap includes a muzzle brake configuration comprising a circular capillary cap outlet opening and an extension slot along the side wall of the capillary cap.

8. An ion injector, including an ion injector inlet and an ion injector outlet, is equipped with a capillary cap that can be placed at the ion injector outlet, The capillary cap includes a capillary cap outlet opening that is shaped and sized to reduce gas turbulence after the ion injector outlet and improve ion signal stability. Device.

9. The apparatus according to claim 8, wherein the capillary cap outlet opening includes a rectangular slot shape.

10. The apparatus according to claim 9, wherein the rectangular slot shape includes a curved portion.

11. The apparatus according to claim 8, wherein the capillary cap outlet opening includes a cross-slot shape.

12. The apparatus according to claim 8, wherein the capillary cap outlet opening includes a star-shaped slot.

13. The apparatus according to claim 8, wherein the capillary cap includes a muzzle brake configuration comprising a circular capillary cap outlet opening and an extension slot along the side wall of the capillary cap.

14. The apparatus according to claim 8, wherein the capillary cap includes a concave area on the opposite side of the outlet surface of the capillary cap.

15. This includes attaching a capillary cap to the ion injector outlet of an ion injector, which includes an ion injector inlet and an ion injector outlet, The capillary cap includes a capillary cap outlet opening that is shaped and sized to reduce gas turbulence after the ion injector outlet and improve ion signal stability. method.

16. The method according to claim 15, wherein the capillary cap outlet opening includes a rectangular slot shape.

17. The method according to claim 15, wherein the capillary cap outlet opening includes a width smaller than the pore diameter of the ion injector.

18. The method according to claim 15, wherein the capillary cap outlet opening is offset radially with respect to the central longitudinal axis of the ion injector hole.

19. The method according to claim 15, wherein the capillary cap outlet opening includes a cross-slot shape.

20. The method according to claim 15, wherein the capillary cap includes a muzzle brake configuration comprising a circular capillary cap outlet opening and an extension slot along the side wall of the capillary cap.

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