A discontinuous sample injection ion trap mass spectrometer

Abstract

The application relates to a mass spectrometer in an analytical instrument, in particular to a non-continuous sampling ion trap mass spectrometer, which comprises a hollow sealed cylindrical chamber, a tail gas outlet connected with a vacuum pump is arranged on one side wall of the chamber; a rectangular ion trap mass spectrometer is arranged in the chamber, which comprises an X electrode pair with an ion outlet slit, a Y electrode pair, a Z electrode pair composed of two-plate flat electrodes with through holes in the middle, a metal electrode pair composed of two-plate flat electrodes with through holes in the middle is arranged outside the two electrodes of the Z electrode pair (6); the electrodes of the Z electrode pair are located between the electrodes of the two metal electrode pairs; the X electrode pair, the Y electrode pair and the Z electrode pair respectively comprise two-plate flat electrodes which are arranged in parallel and are spaced apart; a long strip-shaped ion receiver is arranged at the position outside the X electrode pair and opposite to the ion outlet slit.

Description

Technical Field

[0001] This invention relates to mass spectrometers in analytical instruments, specifically a discontinuous injection ion trap mass spectrometer that achieves efficient cooling of ions within the ion trap through a dual-pulse injection system, thereby improving sensitivity and resolution. Background Technology

[0002] The development and application of in-situ ionization and small portable mass spectrometry are current research hotspots in the field of chemical measurement. Analytical detection techniques based on in-situ ionization small portable mass spectrometry eliminate the need for chromatographic separation and simplify or eliminate sample pretreatment processes, overcoming the drawbacks of traditional detection techniques that are cumbersome and time-consuming. They enable highly sensitive, high-throughput, and rapid on-site sample detection, reflecting an important trend in chemical measurement towards rapid efficiency, real-time in-situ processing, high sensitivity and specificity, and environmental friendliness. These techniques have been widely applied in fields such as food safety, consumer product safety, public safety, life sciences, and environmental monitoring.

[0003] Portable mass spectrometry in the field mainly includes quadrupole mass spectrometry, time-of-flight mass spectrometry, and ion trap mass spectrometry. Among them, ion trap mass spectrometry has attracted widespread attention due to its advantages such as small size and high resolution. Ion trap mass spectrometry can be divided into discontinuous injection and continuous injection according to different sample introduction methods. Continuous injection often requires a multi-stage differential vacuum system, which increases the volume; discontinuous injection can reduce the volume, but the gas pressure gradually decreases during ion cooling, resulting in poor cooling effect. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a discontinuous injection mass spectrometer that achieves efficient cooling of ions in the ion trap through a dual-pulse injection system, thereby improving the mass spectrometer sensitivity and resolution.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A discontinuous injection ion trap mass spectrometer is characterized by: a hollow, sealed cylindrical chamber (1) with a tail gas outlet (2) connected to a vacuum pump on one side wall of the chamber; a rectangular ion trap mass spectrometer is provided inside the chamber, including an X electrode pair (3) with an ion outlet slit (4), a Y electrode pair (5), and a Z electrode pair (6) consisting of two plate-shaped electrodes with through holes in the middle; a metal electrode pair (7) consisting of two plate-shaped electrodes with through holes in the middle is provided outside the two electrodes of the Z electrode pair (6); the electrodes of the Z electrode pair (6) are located on the electrodes of the two metal electrode pairs (7). Between the electrodes, the two electrodes of the Z electrode pair (6) and the two electrodes of the metal electrode pair (7) are parallel to each other, coaxial with the through hole in the middle, and spaced apart; the X electrode pair (3), Y electrode pair (5), and Z electrode pair (6) each include two parallel and spaced plate-shaped electrodes. The plate-shaped electrodes of the X electrode pair (3), Y electrode pair (5), and Z electrode pair (6) are located on the six faces of the same cuboid. The plane where the electrodes of the X electrode pair are located is perpendicular to the plane where the electrodes of the Y electrode pair are located, and the plane where the electrodes of the X electrode pair are located is perpendicular to the plane where the electrodes of the Z electrode pair are located. The planes where the electrodes of the Y electrode pair and the Z electrode pair are located are perpendicular to each other; the ion outlet slit (4) is a strip-shaped through hole that is set in the middle of one or two flat electrodes of the X electrode pair (3) and perpendicular to the Z electrode pair; metal capillaries A (9) that pass through the side walls of the cavity are respectively provided on the two opposite side walls of the cavity near the metal electrode pair (7); one end of the metal capillaries A (9) located outside the cavity is connected to one end of another metal capillaries B (10) through a silicone tube (11); a clamp valve (8) is provided at the silicone tube (11) to form a pulse injection system; a long strip-shaped ion receiver is provided on the outside of the X electrode pair (3) and directly opposite the ion outlet slit (4).

[0007] The mass spectrometer is characterized in that: a glass thin film layer for avoiding the adsorption of pollutants is provided on the inner surface of the two opposing electrodes of the X electrode pair (3), Y electrode pair (5) and Z electrode pair (6).

[0008] The mass spectrometer is characterized in that: the two metal capillaries A / B of the pulse injection system are used for ion implantation and buffer gas injection, respectively; the pulse injection of ion implantation and the pulse injection of buffer gas operate according to a set timing sequence. First, the pulse injection of ion implantation is turned on, and after ion implantation is completed, the pulse injection of ion implantation is turned off, and the pulse injection of buffer gas injection is turned on; the time for the pulse injection of buffer gas injection to be turned on is less than or equal to the time for the pulse injection to maintain stable gas pressure in the ion trap.

[0009] The mass spectrometer is characterized in that: the open end of the metal capillary A (9) located in the cavity is set facing the middle through hole of the metal electrode pair (7).

[0010] The mass spectrometer is characterized in that the thickness of the glass thin film layer is less than or equal to 1 mm.

[0011] The mass spectrometer is characterized in that: the potential on the Z electrode pair (6) is zero; and there is a voltage difference between it and the metal electrode (7) located on the same side: when positive ions are detected, the electric field direction is from the metal electrode pair (7) and the electrode (6) located on the same side; when negative ions are detected, the electric field direction is from the Z electrode pair (6) to the electrode (7) located on the same side.

[0012] The mass spectrometer is characterized in that the ion detector can be an electron multiplier, a microchannel plate, a scintillation detector, or an induced charge detector.

[0013] The advantages of this invention are: This invention provides an atmospheric pressure ionization source with ion spatial focusing function. By using a spindle-shaped structure design combined with a radio frequency electric field, the surface ionization source can be adjusted into a point ionization source, thereby improving the ion introduction efficiency of mass spectrometry. Attached Figure Description

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0015] Figure 1 Schematic diagram of the structure of an ion trap mass spectrometer. Sealed cylindrical chamber (1), exhaust outlet (2), X electrode pair (3), ion outlet slit (4), Y electrode pair (5), Z electrode pair (6), metal electrode pair (7), clamp valve (8), metal capillary (9), metal capillary (10), silicone tube (11). Detailed Implementation

[0016] A discontinuous injection ion trap mass spectrometer

[0017] It includes a hollow, sealed cylindrical chamber 1 (with a volume of 10cm*10cm*8cm), and an exhaust gas outlet 2 connected to a vacuum pump is provided on one side wall of the chamber.

[0018] A rectangular ion trap mass spectrometer is installed inside the cavity, including an X electrode pair 3 with an ion outlet slit 4, a Y electrode pair 5, and a Z electrode pair 6 consisting of two plate-shaped electrodes with a central through-hole. A metal electrode pair 7 consisting of two plate-shaped electrodes with a central through-hole is located outside the two electrodes of the Z electrode pair 6. The Y electrode pair measures 43mm x 10mm; the X electrode pair measures 43mm x 8mm.

[0019] The Z electrode pair 6 is located between the electrodes of the two metal electrode pairs 7. The two electrodes of the Z electrode pair 6 and the two electrodes of the metal electrode pair 7 are parallel to each other, coaxial with the through hole in the middle, and spaced apart. The distance between the Z electrode pairs 6 is 43mm. The size of an adjacent piece in the Z electrode pair 6 and the metal electrode pair 7 is 5mm.

[0020] The X electrode pair 3, Y electrode pair 5, and Z electrode pair 6 each include two parallel and spaced-apart plate-shaped electrodes. The plate-shaped electrodes of the X electrode pair 3, Y electrode pair 5, and Z electrode pair 6 are located on the six faces of the same cuboid. The plane where the electrodes of the X electrode pair are located is perpendicular to the plane where the electrodes of the Y electrode pair are located, the plane where the electrodes of the X electrode pair are located is perpendicular to the plane where the electrodes of the Z electrode pair are located, and the plane where the electrodes of the Y electrode pair are located is perpendicular to the plane where the electrodes of the Z electrode pair are located. The ion outlet slit 4 is a strip-shaped through hole located in the middle of one or two plate-shaped electrodes of the X electrode pair 3, perpendicular to the Z electrode pair electrode. The slit width is 1 mm and the length is 3 cm.

[0021] Metal capillaries A9 are respectively provided on the two opposite side walls of the cavity near the metal electrode pair 7, passing through the side walls of the cavity. One end of the metal capillaries A9 located outside the cavity is connected to one end of another metal capillary B10 through a silicone tube 11. A clamp valve 8 is provided at the silicone tube 11, forming a pulse injection system. The length of the metal capillary B10 is 30 mm; the length of the metal capillary A9 is 60 mm.

[0022] An elongated ion receiver, which is an electron multiplier, is provided on the outside of the X electrode pair 3, directly opposite the ion outlet slit 4.

[0023] A glass thin film layer with a thickness of 50 μm is provided on the inner surface of the two opposing electrodes of the X electrode pair 3, Y electrode pair 5 and Z electrode pair 6 respectively to prevent the adsorption of pollutants.

[0024] The pulse injection system has two metal capillaries, A and B, used for ion implantation and buffer gas injection, respectively. The pulse injection for ion implantation and the pulse injection for buffer gas injection operate according to a set timing sequence. First, the pulse injection for ion implantation is started for 18 ms, and after ion implantation is completed, the pulse injection for ion implantation is turned off, while the pulse injection for buffer gas injection is started for 5 ms.

[0025] The metal capillary A9 located inside the cavity has its open end facing the through hole in the middle of the metal electrode pair 7.

[0026] There is a voltage difference between electrode pair 6 and metal electrode 7 located on the same side:

[0027] When positive ions are detected, the voltage difference between the Z electrode pair 6 and the metal electrode 7 located on the same side is 20V, and the electric field direction is from the metal electrode pair 7 and the electrode 6 located on the same side; when negative ions are detected, the voltage difference between the Z electrode pair 6 and the metal electrode 7 located on the same side is 20V, and the electric field direction is from the Z electrode pair 6 to the electrode 7 located on the same side.

[0028] This invention relates to a discontinuous injection ion trap mass spectrometer. The distances between the counter electrodes of X, Y, and Z are 8 mm, 10 mm, and 43 mm, respectively. The slit size is 1 mm × 15 mm. The voltage parameters applied to the X electrode are: radio frequency 952 kHz, confinement radio frequency voltage 415 V, and AC frequency 345 kHz. The detector is an electron multiplier.

Claims

1. A discontinuous injection ion trap mass spectrometer, characterized in that: It includes a hollow, sealed cylindrical chamber (1), and a tail gas outlet (2) connected to a vacuum pump is provided on one side wall of the chamber. A rectangular ion trap mass spectrometer is provided inside the cavity, including an X electrode pair (3) with an ion outlet slit (4), a Y electrode pair (5), a Z electrode pair (6) consisting of two plate-shaped electrodes with through holes in the middle, and a metal electrode pair (7) consisting of two plate-shaped electrodes with through holes in the middle on the outside of the two electrodes of the Z electrode pair (6). The electrodes of the Z electrode pair (6) are located between the electrodes of the two metal electrode pairs (7). The two electrodes of the Z electrode pair (6) and the two electrodes of the metal electrode pair (7) are parallel to each other, coaxial with the through hole in the middle, and spaced apart. The X electrode pair (3), Y electrode pair (5), and Z electrode pair (6) each include two parallel and spaced-apart plate-shaped electrodes. The plate-shaped electrodes of the X electrode pair (3), Y electrode pair (5), and Z electrode pair (6) are located on the six faces of the same cuboid. The plane where the electrode of the X electrode pair is located is perpendicular to the plane where the electrode of the Y electrode pair is located. The plane where the electrode of the X electrode pair is located is perpendicular to the plane where the electrode of the Z electrode pair is located. The plane where the electrode of the Y electrode pair is located is perpendicular to the plane where the electrode of the Z electrode pair is located. The ion outlet slit (4) is a strip-shaped through hole located in the middle of one or two plate-shaped electrodes of the X electrode pair (3) and perpendicular to the Z electrode pair electrode. Metal capillary tubes A (9) that pass through the side walls of the cavity are respectively provided on the two opposite side walls of the cavity near the metal electrode pair (7). One end of the metal capillary tube A (9) located outside the cavity is connected to one end of another metal capillary tube B (10) through a silicone tube (11). A clamp valve (8) is provided at the silicone tube (11) to form a pulse injection system. An elongated ion receiver is provided on the outside of the X electrode pair (3) and directly opposite the ion outlet slit (4).

2. The mass spectrometer according to claim 1, characterized in that: A glass film layer is provided on the inner surface of the two opposing electrodes of the X electrode pair (3), Y electrode pair (5) and Z electrode pair (6) respectively to avoid adsorbing pollutants.

3. The mass spectrometer according to claim 1, characterized in that: The two metal capillaries A / B of the pulse injection system are used for ion implantation and buffer gas injection, respectively. The pulse injection of ion implantation and the pulse injection of buffer gas operate in a set sequence. First, the pulse injection of ion implantation is turned on, and after the ion implantation is completed, the pulse injection of ion implantation is turned off, and the pulse injection of buffer gas injection is turned on. The buffer gas injection pulse injection start time is less than or equal to the pulse injection start time to maintain stable gas pressure in the ion trap.

4. The mass spectrometer according to claim 1, characterized in that: The metal capillary A (9) located in the cavity has its open end facing the middle through hole of the metal electrode pair (7).

5. The mass spectrometer according to claim 2, characterized in that: The thickness of the glass thin film layer is less than or equal to 1 mm.

6. The mass spectrometer according to claim 1, characterized in that: There is a voltage difference between the Z electrode pair (6) and the metal electrode (7) located on the same side: When positive ions are detected, the electric field direction is from the metal electrode pair (7) and the electrode (6) located on the same side; when negative ions are detected, the electric field direction is from the Z electrode pair (6) to the electrode (7) located on the same side.

7. The mass spectrometer of claim 1, wherein: Ion detectors can be electron multipliers, microchannel plates, scintillation detectors, or induced charge detectors.

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