High-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry combined device

Abstract

The invention relates to a high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry combined device which comprises a closed container, a planar electrode pair is arranged in the closed container, and the surfaces of two electrodes of the planar electrode pair are perpendicular to an X axis; a flat plate Y electrode pair and a flat plate Z electrode pair which are formed by two rectangular flat plate-shaped electrodes which are arranged in parallel at intervals are arranged between the planar end electrode pairs; the electrode surfaces of the flat plate Y electrode pair and the flat plate Z electrode pair are respectively vertical to the Y axis and the Z axis; an ion outlet of the ionization source is located above the area between the high-voltage electrode and the left side end electrode and faces the area between the high-voltage electrode and the left side end electrode; and a gas inlet of the sucking pump penetrates through the wall surface of the closed container and extends into an area between the flat plate Y electrode pair or the flat plate Z electrode pair and the left side end electrode. Through the pre-separation function of the high-field asymmetric waveform ion mobility spectrometry, non-target compound ions are prevented from entering the ion trap, so that the resolution ratio and peak position stability of the ion trap are ensured.

Description

Technical Field

[0001] The present invention is a high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device, which realizes two-dimensional separation and analysis by designing a cascade connection; the pre-separation of the high-field asymmetric waveform ion mobility spectrometry is utilized to realize the selective entry of ions into the ion trap and avoid peak broadening and peak position drift caused by the Coulomb effect in the ion trap. Background Art

[0002] Ion mobility spectrometry is widely used in the detection of chemical agents, drugs, stimulants, anesthetics and explosives due to its advantages of high sensitivity, fast analysis speed and portability. The different flight times of different ions in a uniform field under atmospheric pressure are used to separate and analyze different substances. High-field asymmetric waveform ion mobility spectrometry is a material analysis and detection technology that has been continuously developed based on traditional ion mobility spectrometry technology. It is based on the change in ion mobility in high field (E / N>40Td, 1Td=10-17Vcm2) and low field (E / N<2Td) to detect different substances. The principle of asymmetric field ion mobility spectrometry is as follows: the carrier gas is used to make the material ions pass through the drift region perpendicular to the direction of the electric field, and the drift region is applied with an asymmetric field with positive and negative switching of radio frequency. During the entire radio frequency cycle, the time average value of the voltage is zero. In this way, in the high and low field sections, the ions have a vertical displacement along the electric field at a mobility K. However, if the mobility under high field and low field is different, the ions will generally leave their original positions in the vertical direction within a cycle, resulting in a net displacement. After a certain period of accumulation, the displacement of the ions will cause them to hit the plate and be neutralized. In order to allow the ions to pass through the detection area smoothly, a DC electric field can be superimposed on the original electric field. When the DC electric field is appropriate, the net displacement of the ions in the vertical direction is zero, and they can pass through the detection channel smoothly and be detected. By scanning the above DC electric field, different ions can be detected.

[0003] High-field asymmetric waveform ion mobility spectrometry can achieve the separation of compounds with the same molecular weight but different structures, and can achieve the separation and analysis of isomers when combined with mass spectrometry. In addition, in the field of protein analysis, high-field asymmetric waveform ion mobility spectrometry can be used as a pre-separation stage for mass spectrometry to eliminate low-molecular-weight compounds from entering the mass spectrometry, greatly reduce background noise, improve signal-to-noise ratio, and increase sensitivity by 3 orders of magnitude. When traditional high-field asymmetric waveform ion mobility spectrometry is combined with mass spectrometry, only ions at a certain point can enter the mass spectrometry (Journal of the American Society for Mass Spectrometry 1999; 10: 492–501.), with low ion utilization and poor sensitivity. Later, in order to improve ion utilization, a dome structure was proposed (Analytical Chemistry 2005; 77: 6381–6388). At present, high-field asymmetric waveform ion mobility spectrometry has been industrialized and promoted in combination with large-scale desktop instruments such as time-of-flight mass spectrometry and quadrupole mass spectrometry. However, there are few reports on its combination with micro-ion trap mass spectrometry. How to realize the combination of high-field asymmetric waveform ion mobility spectrometry and ion trap mass spectrometry has important research significance and application prospects. Summary of the invention

[0004] The purpose of the present invention is to combine micro high-field asymmetric waveform ion mobility spectrometry with ion trap mass spectrometry to solve the problem of accurate identification of target compounds in complex matrices during field applications. Through the pre-separation function of high-field asymmetric waveform ion mobility spectrometry, non-target compound ions are prevented from entering the ion trap, thereby ensuring the resolution and peak position stability of the ion trap.

[0005] To achieve this purpose, the technical solution adopted by the present invention is:

[0006] A high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry combined device, comprising a sealed container, a through hole is opened on the left wall surface of the sealed container; a planar electrode pair is arranged inside the sealed container, the planar end electrode pair is composed of two rectangular flat plate electrodes arranged in parallel and spaced apart, and the edges of the left end electrode in the planar electrode pair are sealed and connected to the inner wall surface of the through hole on the sealed container, or one side surface of the left end electrode is sealed and connected to the container wall surface of the edge of the opening end of the through hole on one side of the sealed container;

[0007] The direction from left to right is the X-axis direction, the direction from top to bottom is the Y-axis direction, and the direction perpendicular to the X-axis and Y-axis is the Z-axis direction;

[0008] The surfaces of two electrodes of the planar end electrode pair are perpendicular to the X axis; a planar Y electrode pair consisting of two parallel and spaced rectangular planar electrodes is arranged between the planar end electrode pair, and the electrode surface of the planar Y electrode pair is perpendicular to the Y axis; a planar Z electrode pair consisting of two parallel and spaced rectangular planar electrodes is arranged between the planar end electrode pair, and the electrode surface of the planar Z electrode pair is perpendicular to the Z axis; the area surrounded by the planar end electrode pair, the planar Y electrode pair, and the planar Z electrode pair constitutes an ion trap area;

[0009] Apply radio frequency high voltage and alternating current low voltage to the flat Z electrode pair, apply radio frequency high voltage or grounding which is 180° out of phase with the radio frequency voltage on the Z electrode pair to the flat Y electrode pair; the spacing between the flat Z electrode pairs is greater than the spacing between the flat Y electrode pairs; a corresponding slit is provided in the middle of one or two electrodes in the flat Z electrode pair along the X-axis direction, the slit is parallel to the X-axis, and the slit passes through the two side surfaces of the two electrodes perpendicular to the Z-axis; apply a DC voltage to the planar end electrode pair;

[0010] A through hole A serving as a sampling microhole is provided in the middle of the left end electrode of the planar end electrode pair (the through hole A is located in the through hole corresponding area on the sealed container, that is, the inside and outside of the sealed container can be connected through the sampling microhole) to achieve the regulation of the air pressure on both sides;

[0011] A rectangular flat high-voltage electrode is provided on the left side of the left end electrode and is arranged parallel to the left end electrode, and the upper edges of the left end electrode and the high-voltage electrode are aligned (i.e., they are on the same horizontal plane), and the lower edge of the high-voltage electrode does not exceed the upper edge of the sampling micropore opening end on the left end electrode (i.e., the upper edge of the opening end, the horizontal plane where the lower edge of the high-voltage electrode is located is on the same horizontal plane as the upper edge of the opening end, or above the horizontal plane where the upper edge of the opening end is located);

[0012] An ion migration region is formed in a region between the high voltage electrode and the left end electrode of the planar end electrode pair;

[0013] an ion source, the ion outlet of which is located above the area between the high voltage electrode and the left end electrode and faces the area between the high voltage electrode and the left end electrode;

[0014] A vacuum pump, the gas inlet of which passes through the wall of the closed container and extends into the area between the flat plate Y electrode pair or the flat plate Z electrode pair and the left end electrode.

[0015] The diameter of the sampling micropore is less than or equal to 1mm, and the thickness of the end electrode is less than or equal to 1cm; the air pressure at the high pressure end on the left side of the end electrode ranges from 100Pa to atmospheric pressure; the air pressure at the low pressure end on the right side of the end electrode is lower than 10-1Pa;

[0016] One side of the flat plate Y electrode pair and the flat plate Z electrode pair (the side close to the left end electrode) is a low pressure area, and the opposite side (and the other side of the left end electrode) is a high pressure area.

[0017] Applying a high-field asymmetric waveform voltage to the high-voltage electrode, with a frequency of 0.1 MHz to 100 MHz, a high-field voltage of 1000 V to 10000 V, and a low-field voltage of 100 V to 500 V;

[0018] The frequency of the radio frequency high voltage is 0.5MHz to 20MHz, and the voltage amplitude is 1kV to 5kV;

[0019] The frequency of the AC low voltage is 1 / 3 of the frequency of the radio frequency voltage, and the amplitude is between 0.1V and 5V.

[0020] A DC voltage is applied to the planar end electrode pair, with a voltage range of 1 to 50V.

[0021] The distance between the left end electrode and the high voltage electrode is less than or equal to 2 mm.

[0022] An ion detector is arranged outside the ion trap region near the slit. The ion detector can be one or more of an electron multiplier, a Faraday cup detector, a scintillation photomultiplier, and a microchannel plate detector.

[0023] The ionization source may be one or more of a single photon ionization source, an electrospray ionization source, a discharge ionization source, and a radioactive ionization source.

[0024] It can provide mobility change, mass-to-nuclear ratio and intensity information to achieve accurate qualitative analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 .Schematic diagram of the principle of high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry combined device.

[0026] Ionization source (1), high voltage electrode (2), left end electrode (3), sampling micropore (4), Y electrode pair (5, 5'), flat plate Z electrode pair (6, 6'), slit (7), right end electrode (3')

[0027] Figure 2 .Typical spectrum of aniline determined by high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry (the upper figure is the result without high-field asymmetric waveform ion mobility spectrometry pre-separation, and the lower figure is the result with high-field asymmetric waveform ion mobility spectrometry). DETAILED DESCRIPTION

[0028] like Figure 1As shown, a high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry combined device comprises a sealed container, a through hole is opened on the left wall surface of the sealed container; a planar electrode pair 3, 3' is arranged therein, the planar end electrode pair 3, 3' is composed of two rectangular flat plate electrodes arranged in parallel and spaced apart, and the edges of the left end electrode 3 in the planar electrode pair 3, 3' are sealed and connected to the inner wall surface of the through hole on the sealed container, or one side surface of the left end electrode 3 is sealed and connected to the container wall surface of the edge of the opening end of one side of the through hole on the sealed container;

[0029] The direction from left to right is the X-axis direction, the direction from top to bottom is the Y-axis direction, and the direction perpendicular to the X-axis and Y-axis is the Z-axis direction;

[0030] The surfaces of two electrodes of the planar end electrode pair 3, 3' are perpendicular to the X axis; a planar Y electrode pair 5, 5' consisting of two parallel and spaced rectangular planar electrodes is arranged between the planar end electrode pair 3, 3', and the electrode surfaces of the planar Y electrode pair 5, 5' are perpendicular to the Y axis; a planar Z electrode pair 6, 6' consisting of two parallel and spaced rectangular planar electrodes is arranged between the planar end electrode pair 3, 3', and the electrode surfaces of the planar Z electrode pair 6, 6' are perpendicular to the Z axis; the area surrounded by the planar end electrode pair 3, 3', the planar Y electrode pair 5, 5', and the planar Z electrode pair 6, 6' constitutes an ion trap area;

[0031] Apply radio frequency high voltage and AC low voltage to the flat Z electrode pair, and apply radio frequency high voltage or ground (grounded here) that is 180° out of phase with the radio frequency voltage on the Z electrode pair to the flat Y electrode pair; the spacing between the flat Z electrode pair 6, 6' is greater than the spacing between the flat Y electrode pair 5, 5'; a corresponding slit 7 is opened in the middle of one electrode in the flat Z electrode pair 6, 6' along the X-axis direction, the slit 7 is parallel to the X-axis, and the slit 7 passes through the two side surfaces of the electrode perpendicular to the Z-axis; apply a DC voltage to the plane end electrode pair 3, 3';

[0032] A through hole A serving as a sampling microhole 4 is provided in the middle of the left end electrode 3 of the planar end electrode pair 3, 3' (the through hole A is located in the through hole corresponding area on the sealed container, i.e., the inside and outside of the sealed container can be connected through the sampling microhole 4) to achieve the regulation of the air pressure on both sides;

[0033] A rectangular flat high-voltage electrode 2 is provided on the left side of the left end electrode 3 and is arranged parallel to the left end electrode 3, and the upper edges of the left end electrode 3 and the high-voltage electrode 2 are aligned (i.e., they are on the same horizontal plane), and the lower edge of the high-voltage electrode 2 does not exceed the upper edge of the opening end of the sampling microhole 4 on the left end electrode 3 (i.e., the upper edge of the opening end, the horizontal plane where the lower edge of the high-voltage electrode 2 is located is on the same horizontal plane as the upper edge of the opening end, or above the horizontal plane where the upper edge of the opening end is located);

[0034] The area between the high voltage electrode 2 and the left end electrode 3 in the planar end electrode pair 3, 3' constitutes an ion migration area;

[0035] an ion source, the ion outlet of which is located above the area between the high voltage electrode 2 and the left end electrode 3 and faces the area between the high voltage electrode 2 and the left end electrode 3;

[0036] A vacuum pump, the gas inlet of which passes through the wall of the sealed container and extends into the area between the flat plate Y electrode pair 5, 5' or the flat plate Z electrode pair 6, 6' and the left end electrode 3.

[0037] The diameter of the sampling micropore 4 is 0.3 mm, and the thickness of the end electrode 3 is 3 mm; the pressure at the high pressure end on the left side of the end electrode 3 is atmospheric pressure; the pressure at the low pressure end on the right side of the end electrode 3 is 10 -3 Pa;

[0038] One side of the flat plate Y electrode pair 5, 5' and the flat plate Z electrode pair 6, 6' (or the side close to the left end electrode 3) is a low pressure area, and the opposite side (or the other side of the left end electrode 3) is a high pressure area.

[0039] A high-field asymmetric waveform voltage is applied to the high-voltage electrode 2, with a frequency of 1.5 MHz, a high-field voltage of 3000 V, and a low-field voltage of 500 V;

[0040] The frequency of the radio frequency high voltage is 1 MHz, and the voltage amplitude is 3 kV;

[0041] The frequency of the AC low voltage is 1 / 3 of the frequency of the radio frequency voltage, and the amplitude is between 0.1V and 5V.

[0042] A DC voltage of 5V is applied to the planar end electrode pair 3, 3'.

[0043] The distance between the left end electrode 3 and the high voltage electrode 2 is equal to 0.8 mm.

[0044] An ion detector is arranged outside the ion trap region near the slit 7, and the ion detector is a Faraday cup detector.

[0045] The ionization source may be an electrospray ionization source.

[0046] It can provide information on mobility change, mass-to-nuclear ratio and intensity, and achieve accurate qualitative analysis. Determination of aniline by focusing ion migration tube: Aniline is ionized by acetone-assisted VUV photochemical ionization source 1 under the action of purified air, and enters the high-field asymmetric field ion migration zone between high-voltage electrode 2 and left end electrode 3 under the action of carrier gas for pre-separation; under the action of pressure difference, it passes through sampling micropore 4 into the ion trap mass analyzer composed of Y electrode pair (5, 5'), flat Z electrode pair (6, 6'), and end electrode pair (3, 3'), and finally passes through slit 7 under the action of axial excitation electric field and is detected by the detector ( Figure 2 ).

Claims

1. A high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device, characterized in that: The invention comprises a sealed container, wherein a through hole is provided on the left wall surface of the sealed container; a planar electrode pair (3, 3') is provided therein, wherein the planar end electrode pair (3, 3') is composed of two rectangular flat plate electrodes arranged in parallel and spaced apart, and the edges of the left end electrode (3) in the planar electrode pair (3, 3') are sealedly connected to the inner wall surface of the through hole on the sealed container, or the surface of one side of the left end electrode (3) is sealedly connected to the container wall surface of the edges of the opening end of the through hole on one side of the sealed container; The direction from left to right is the X-axis direction, the direction from top to bottom is the Y-axis direction, and the direction perpendicular to the X-axis and Y-axis is the Z-axis direction; The surfaces of two electrodes of the planar end electrode pair (3, 3') are perpendicular to the X axis; a planar Y electrode pair (5, 5') consisting of two parallel rectangular flat-plate electrodes arranged at intervals is arranged between the planar end electrode pair (3, 3'), and the electrode surface of the planar Y electrode pair (5, 5') is perpendicular to the Y axis; a planar Z electrode pair (6, 6') consisting of two parallel rectangular flat-plate electrodes arranged at intervals is arranged between the planar end electrode pair (3, 3'), and the electrode surface of the planar Z electrode pair (6, 6') is perpendicular to the Z axis; the area surrounded by the planar end electrode pair (3, 3'), the planar Y electrode pair (5, 5'), and the planar Z electrode pair (6, 6') constitutes an ion trap area; A radio frequency high voltage and an alternating current low voltage are applied to the flat plate Z electrode pair, and a radio frequency high voltage or grounding which is 180° out of phase with the radio frequency voltage on the Z electrode pair is applied to the flat plate Y electrode pair; the spacing between the flat plate Z electrode pair (6, 6') is greater than the spacing between the flat plate Y electrode pair (5, 5'); a corresponding slit (7) is provided in the middle of one or two electrodes in the flat plate Z electrode pair (6, 6') along the X-axis direction, the slit (7) is parallel to the X-axis, and the slit (7) passes through the two side surfaces of the two electrodes perpendicular to the Z-axis; a direct current voltage is applied to the plane end electrode pair (3, 3'); A through hole A serving as a sampling microhole (4) is provided in the middle of the left end electrode (3) of the planar end electrode pair (3, 3') (the through hole A is located in the through hole corresponding area on the sealed container, i.e., the inside and outside of the sealed container can be connected through the sampling microhole (4)) to achieve regulation of air pressure on both sides; A rectangular flat high-voltage electrode (2) is provided on the left side of the left end electrode (3) and is arranged parallel to the left end electrode (3), and the upper edges of the left end electrode (3) and the high-voltage electrode (2) are aligned (i.e., they are on the same horizontal plane), and the lower edge of the high-voltage electrode (2) does not exceed the upper edge of the opening end of the sampling microhole (4) on the left end electrode (3) (i.e., the upper edge of the opening end, the horizontal plane where the lower edge of the high-voltage electrode (2) is located is on the same horizontal plane as the upper edge of the opening end, or is above the horizontal plane where the upper edge of the opening end is located); An ion migration region is formed in the area between the high voltage electrode (2) and the left end electrode (3) in the planar end electrode pair (3, 3'); An ion source (1), whose ion outlet is located above the area between the high-voltage electrode (2) and the left end electrode (3), and faces the area between the high-voltage electrode (2) and the left end electrode (3); A vacuum pump, the gas inlet of which passes through the wall of the sealed container and extends into the area between the flat plate Y electrode pair (5, 5') or the flat plate Z electrode pair (6, 6') and the left end electrode (3).

2. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: The diameter of the sampling micropore (4) is less than or equal to 1 mm, and the thickness of the end electrode (3) is less than or equal to 1 cm; the air pressure at the high-pressure end on the left side of the end electrode (3) ranges from 100 Pa to atmospheric pressure; the air pressure at the low-pressure end on the right side of the end electrode (3) is less than 10 -1 Pa; One side of the flat plate Y electrode pair (5, 5') and the flat plate Z electrode pair (6, 6') (the side close to the left end electrode (3)) is a low pressure area, and the opposite side (and the other side of the left end electrode (3)) is a high pressure area.

3. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: Applying a high-field asymmetric waveform voltage to the high-voltage electrode (2), with a frequency of 0.1 MHz to 100 MHz, a high-field voltage of 1000 V to 10000 V, and a low-field voltage of 100 V to 500 V; The frequency of the radio frequency high voltage is 0.5MHz to 20MHz, and the voltage amplitude is 1kV to 5kV; The frequency of the AC low voltage is 1 / 3 of the frequency of the radio frequency voltage, and the amplitude is between 0.1V and 5V.

4. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: A direct current voltage is applied to the planar end electrode pair (3, 3'), and the voltage range is 1 to 50V.

5. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: The distance between the left end electrode (3) and the high voltage electrode (2) is less than or equal to 2 millimeters.

6. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: An ion detector is arranged outside the ion trap region near the slit (7), and the ion detector can be one or more of an electron multiplier, a Faraday cup detector, a scintillation photomultiplier, and a microchannel plate detector.

7. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: The ionization source may be one or more of a single photon ionization source, an electrospray ionization source, a discharge ionization source, and a radioactive ionization source.

8. The high-field asymmetric waveform ion mobility spectrometry-ion trap mass spectrometry device according to claim 1, characterized in that: It can provide mobility change, mass-to-nuclear ratio and intensity information to achieve accurate qualitative analysis.

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