Efficient asymmetric ion trap mass analyzer

Abstract

The invention discloses a high-efficiency asymmetric ion trap mass analyzer, and relates to the technical field of mass spectrum ion mass analysis, and the high-efficiency asymmetric ion trap mass analyzer comprises a detector, an ion trap body is provided with an ion trap center, the distance between a long-axis electrode and the ion trap center is D1, and the distances between a short-axis electrode and the ion trap center are D2, D1gt; d2, the radio frequency electrode, the long-axis electrode and the short-axis electrode enclose an asymmetric ion trap body, and the detector is arranged close to the short-axis electrode. The distance between the short-axis electrode and the center of the ion trap is shortened, an asymmetric ion trap body is formed, and then an asymmetric electric field is formed, compared with an existing symmetric ion trap mass analyzer, ions are not equivalently ejected from the two ends, more ions can be ejected towards the direction of a detector, the ratio of signals to noise can be increased, and the detection precision is improved. The effect of improving the sensitivity is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of mass spectrometry ion mass analysis, in particular to a high-efficiency asymmetric ion trap mass analyzer. Background Art

[0002] Ion trap mass analyzer is a mass analysis device widely used in mass spectrometers, which confines ions in a certain space through an electric field and performs mass analysis of ions by scanning the electric field. Although the existing symmetrical ion trap mass analyzer has a simple structure, it has certain limitations in sensitivity.

[0003] In view of this, how to provide an ion trap mass analyzer with improved sensitivity is a problem that those skilled in the art need to solve urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a high-efficiency asymmetric ion trap mass analyzer to solve the problems existing in the prior art.

[0005] To achieve the above object, the present invention provides a high-efficiency asymmetric ion trap mass analyzer, wherein the ion trap body is surrounded by a radio frequency electrode, a long-axis electrode and a short-axis electrode, and comprises:

[0006] The detector, wherein the ion trap body has an ion trap center, the distance between the long-axis electrode and the ion trap center is D1, the distance between the short-axis electrode and the ion trap center is D2, D1>D2, the radio frequency electrode, the long-axis electrode and the short-axis electrode form an asymmetric ion trap body, the detector is arranged close to the short-axis electrode, and an asymmetric electric field is formed in the asymmetric ion trap body;

[0007] A front end cover electrode, arranged at the front end of the ion trap body;

[0008] The rear end cover electrode is arranged at the rear end of the ion trap body.

[0009] Furthermore, the radio frequency electrode is electrically connected to a radio frequency generator, the long axis electrode and the short axis electrode are both electrically connected to an auxiliary AC power generator, and the front end cover electrode and the rear end cover electrode are both electrically connected to a DC power supply.

[0010] Furthermore, the RF generator can form a RF voltage between two RF electrodes, and the RF voltage is an amplitude-sweeping sine wave or a frequency-sweeping sine wave, which is used for separation and ejection of ions with different mass-to-charge ratios.

[0011] Furthermore, the RF voltage amplitude is 100 Vpp to 10000 Vpp, and the frequency is 0.5 to 2.5 MHz.

[0012] Furthermore, the auxiliary AC power generator can form an auxiliary AC voltage between the long-axis electrode and the short-axis electrode to form the asymmetric electric field, which is used to assist in ejecting ions and improve mass resolution. The amplitude of the auxiliary AC voltage is 50 to 500 kHz.

[0013] Furthermore, the asymmetric ion trap body is a linear ion trap or a 3D ion trap.

[0014] Furthermore, the radio frequency electrode, the long-axis electrode and the short-axis electrode are all hyperbolic electrodes, with D1 = 4 mm and D2 = 3.7 mm.

[0015] The present invention discloses the following technical effects:

[0016] The detector is set close to the short-axis electrode, shortening the distance between the short-axis electrode and the center of the ion trap, forming an asymmetric ion trap body and then an asymmetric electric field. Compared with the existing symmetric ion trap mass analyzer, ions are not ejected from both ends in equal amounts, and more ions will be ejected toward the detector, which can improve the signal-to-noise ratio and achieve the effect of improving sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the structure of the present invention;

[0019] Figure 2 This is a sensitivity comparison diagram between the present embodiment and the existing symmetric ion trap mass analyzer;

[0020] Among them, 1. radio frequency electrode; 2. short axis electrode; 3. long axis electrode; 4. front end cover electrode; 5. rear end cover electrode; 6. detector. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example

[0024] The embodiment of the present invention provides a high-efficiency asymmetric ion trap mass analyzer, wherein the ion trap body is surrounded by a radio frequency electrode 1, a long axis electrode 3 and a short axis electrode 2, wherein there are two radio frequency electrodes 1, which are respectively arranged at the upper and lower ends, and the long axis electrode 3 and the short axis electrode 2 are located at the left and right ends. The ion trap body has an ion trap center, the distance between the long axis electrode 3 and the ion trap center is D1, the distance between the short axis electrode 2 and the ion trap center is D2, D1>D2, the radio frequency electrode 1, the long axis electrode 3 and the short axis electrode 2 form an asymmetric ion trap body, the detector 6 is arranged close to the short axis electrode 2; the front end cover electrode 4 is arranged at the front end of the ion trap body; the rear end cover electrode 5 is arranged at the rear end of the ion trap body; and an asymmetric electric field is formed in the asymmetric ion trap body.

[0025] In this embodiment, the RF electrode 1 is electrically connected to the RF generator, the long-axis electrode 3 and the short-axis electrode 2 are both electrically connected to the auxiliary AC power generator, and the front cover electrode 4 and the rear cover electrode 5 are both electrically connected to the DC power supply. The RF signal generated by the RF generator is applied to the two RF electrodes 1, and the RF generator can form a RF voltage between the two RF electrodes 1, and the RF voltage is an amplitude sweeping sine wave or a frequency sweeping sine wave.

[0026] The auxiliary AC power generator applies auxiliary AC signals with opposite phases to the two long-axis electrodes 3 and the short-axis electrode 2, respectively, to form an auxiliary AC voltage between the long-axis electrode 3 and the short-axis electrode 2, and then to form an asymmetric electric field between the long-axis electrode 3 and the short-axis electrode 2, which is used to assist in ejecting ions and improve mass resolution. A DC voltage is applied to the front and rear end cover electrodes 5 respectively through a DC power supply.

[0027] In this embodiment, the asymmetric ion trap body is a linear ion trap. In some other embodiments, the asymmetric ion trap body can also be a 3D ion trap, etc. The asymmetric ion trap test process is divided into three stages: injection, cooling, and mass analysis. The duration of each stage can be arbitrarily adjusted in units of 1 ms within 0 to 4000 ms. The background gas of the asymmetric ion trap body can be one or more of hydrogen, helium, argon, nitrogen or dry air, and the gas pressure can be 0.1 Pa to tens of Pa.

[0028] In this embodiment, the RF electrode 1, the long-axis electrode 3 and the short-axis electrode 2 are all hyperbolic electrodes, D1 = 4 mm, D2 = 3.7 mm, the RF voltage amplitude is 300 Vpp-5000 Vpp, the frequency is 1.2 MHz, the auxiliary AC voltage amplitude is 0.5-2 V, and the frequency is 330 kHz.

[0029] The specific working process is as follows:

[0030] Injection phase (20ms):

[0031] The front cover electrode 4 is set to 0V, and the ions can obtain the initial velocity into the trap through the pressure difference, and the rear cover electrode 5 is set to +100V to prevent the ions from escaping; the ions are captured under the RF electric field and collision cooling with the gas.

[0032] Cooling phase (10ms):

[0033] The front and rear end cover electrodes 5 are simultaneously set to +100V to achieve axial confinement of the ions; at the same time, the radio frequency electric field achieves radial confinement of the ions, causing the ion clusters to aggregate.

[0034] Quality analysis phase (200ms):

[0035] Keep the front and rear end cover electrodes 5 at +100V, apply RF voltage to the RF electrode 1, and change the amplitude of the RF signal linearly with time, and finally realize the separation and ejection of ions in order from small to large mass-to-charge ratio. At the same time, auxiliary AC signals with opposite phases are applied to the long-axis electrode 3 and the short-axis electrode 2 respectively to assist in ejecting ions and improve mass resolution. Since the existing symmetrical ion trap mass analyzer will eject ions equally at both ends during analysis, for a mass spectrometer with only a single detector 6, only a maximum of 50% of the ions can be detected, so the sensitivity is not high; and this embodiment can make more ions ejected to one end of the detector 6, thereby improving the signal-to-noise ratio, that is, improving the sensitivity.

[0036] Test example

[0037] Experimental conditions: 1 ppm atenolol and 500 ppb imatinib were used as samples, and NanoESI was used as the ionization source. The results were analyzed by the present embodiment and the existing symmetric ion trap mass analyzer (4 mm ion trap and 3.7 mm ion trap). Figure 2 shown.

[0038] It can be seen that for 1 ppm atenolol, the intensity of this embodiment is improved by 25% compared with the existing symmetric ion trap mass analyzer; for 500 ppb imatinib, the intensity of this embodiment is improved by 62% compared with the 3.7 mm ion trap and by 113% compared with the 4 mm ion trap.

[0039] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0040] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A high-efficiency asymmetric ion trap mass analyzer, wherein the ion trap body is surrounded by a radio frequency electrode (1), a long-axis electrode (3) and a short-axis electrode (2), characterized in that: include: A detector (6), wherein the ion trap body has an ion trap center, the distance between the long-axis electrode (3) and the ion trap center is D1, the distance between the short-axis electrode (2) and the ion trap center is D2, D1>D2, the radio frequency electrode (1), the long-axis electrode (3) and the short-axis electrode (2) form an asymmetric ion trap body, the detector (6) is arranged close to the short-axis electrode (2), and an asymmetric electric field is formed in the asymmetric ion trap body; A front end cover electrode (4) is arranged at the front end of the ion trap body; A rear end cover electrode (5) is arranged at the rear end of the ion trap body.

2. A high-efficiency asymmetric ion trap mass analyzer according to claim 1, characterized in that: The radio frequency electrode (1) is electrically connected to a radio frequency generator, the long axis electrode (3) and the short axis electrode (2) are both electrically connected to an auxiliary AC power generator, and the front end cover electrode (4) and the rear end cover electrode (5) are both electrically connected to a DC power supply.

3. A high-efficiency asymmetric ion trap mass analyzer according to claim 2, characterized in that: The radio frequency generator can form a radio frequency voltage between two radio frequency electrodes (1), wherein the radio frequency voltage is an amplitude sweeping sine wave or a frequency sweeping sine wave, and is used for separation and ejection of ions with different mass-to-charge ratios.

4. A high-efficiency asymmetric ion trap mass analyzer according to claim 3, characterized in that: The RF voltage amplitude is 100 Vpp to 10000 Vpp, and the frequency is 0.5 to 2.5 MHz.

5. The high-efficiency asymmetric ion trap mass analyzer according to claim 3, characterized in that: The auxiliary AC power generator can form an auxiliary AC voltage between the long-axis electrode (3) and the short-axis electrode (2), thereby forming the asymmetric electric field for ejecting ions.

6. The high-efficiency asymmetric ion trap mass analyzer according to claim 1, characterized in that: The asymmetric ion trap body is a linear ion trap or a 3D ion trap.

7. The high-efficiency asymmetric ion trap mass analyzer according to claim 1, characterized in that: The radio frequency electrode (1), the long-axis electrode (3) and the short-axis electrode (2) are all hyperbolic electrodes.

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