Tandem mass spectrometer, collision cell and working method thereof

Abstract

The present invention relates to a tandem mass spectrometer and a collision cell and a working method thereof. The collision cell of the tandem mass spectrometer comprises: a chamber, a front-stage high-order field N-pole and a rear-stage quadrupole. After ions with a wider mass range enter the chamber through an introduction center hole of an introduction electrode, they can smoothly enter the front-stage high-order field N-pole, and the front-stage high-order field N-pole can capture ions with a wider mass range. In addition, collision gas enters the chamber corresponding to the front-stage high-order field N-pole through a vent, and the collision gas collides with the ions entering the front-stage high-order field N-pole, so that the ions are cracked to form fragments. The rear-stage quadrupole can realize that the fragmented and wider range of fragment ions are concentrated near the central axis, so that the fragment ions have a better focusing effect, and efficiently pass through the extraction center hole of the extraction electrode, that is, the ion mass range can be wider and the transmission efficiency can be higher, and the residence time of the ions in the high-pressure collision cell can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of mass spectrometry, and in particular to a tandem mass spectrometer and a collision cell and a working method thereof. Background Art

[0002] With the development of mass spectrometry technology, tandem mass spectrometers have emerged. Tandem mass spectrometers can combine multiple advantages such as high-speed analysis, high sensitivity, high resolution, and high accuracy. They have higher sensitivity and qualitative and quantitative analysis capabilities, and are the development trend of mass spectrometers. As the core component of tandem mass spectrometers, collision cells are used for multi-stage mass analysis (MSn) of ions: fragment ions generated by the parent ion collision reaction can be analyzed by mass analysis to obtain the structural information of the parent ion, as well as qualitative and quantitative analysis of the ion.

[0003] Since the gas pressure in the collision cell is generally high (mtorr level), after the ions collide, they will change their direction of movement and deviate from the central transmission area with the highest ion transmission efficiency, resulting in reduced ion transmission efficiency. Therefore, a multi-pole structure working in RF-only mode is often used to focus the ions that are discrete due to collisions, such as Agilent's hexapole structure and AB's quadrupole structure. From the multipole pseudopotential calculation formula, it can be seen that as the field order increases, the potential tends to be flat, which can accommodate ions with a wider mass range and high energy distribution; while the potential of the near-axis of the low-order field (such as the quadrupole) is narrower, which can focus the ions near the central axis, thereby achieving effective transmission and making it easier to pass through the small-aperture exit hole at the rear end. Therefore, the transmission range and transmission efficiency of ions are different due to different multipole structures, and they cannot be taken into account at the same time. Summary of the invention

[0004] Based on this, it is necessary to overcome the defects of the prior art and provide a tandem mass spectrometer and its collision cell and working method, which can achieve a wider ion mass range and higher transmission efficiency.

[0005] The technical scheme is as follows: a collision cell of a tandem mass spectrometer, the collision cell of the tandem mass spectrometer comprising: a chamber, the front end of the chamber is provided with an introduction electrode, the introduction electrode is provided with an introduction center hole, the rear end of the chamber is provided with an extraction electrode, the extraction electrode is provided with an extraction center hole; a front section high-order field N-pole rod and a rear section quadrupole rod, the front section high-order field N-pole rod and the rear section quadrupole rod are arranged in sequence along the central axis of the chamber, wherein N is an even number greater than 4, and a vent for introducing collision gas is arranged at a position of the side wall of the chamber corresponding to the front section high-order field N-pole rod; the poles of the front section high-order field N-pole rod include poles spaced coaxially in sequence The invention relates to a quadrupole comprising two or more first segments arranged at intervals from each other, and a first insulating member connected between two adjacent first segments, a first resistor and a first capacitor connected in parallel are connected in series between two adjacent first segments, and the polarities of the adjacent poles of the front high-order field N-pole are opposite; the poles of the rear quadrupole comprise two or more second segments arranged coaxially and spaced in sequence, and a second insulating member connected between two adjacent second segments, a second resistor and a second capacitor connected in parallel are connected in series between two adjacent second segments, and the first segment of the rear quadrupole is connected to the first segment of the front high-order field N-pole through a third resistor.

[0006] Compared with the collision cell of the traditional tandem mass spectrometer, the collision cell of the above-mentioned tandem mass spectrometer adopts the form of combining the front-stage high-order field N-pole and the rear-stage quadrupole and sequentially arranging them in the chamber along the central axis of the chamber, so that ions with a wider mass range can smoothly enter the front-stage high-order field N-pole after entering the chamber through the introduction center hole of the introduction electrode. The front-stage high-order field N-pole can capture ions with a wider mass range due to its relatively flat potential. In addition, the collision gas enters the chamber corresponding to the front-stage high-order field N-pole through the air vent, and the collision gas collides with the ions entering the front-stage high-order field N-pole, so that the ions are cracked to form fragments. The rear-stage quadrupole can realize the concentration of the fragmented fragments near the central axis, so that the focusing effect of the fragmented ions is better, and the fragments can efficiently pass through the extraction center hole of the extraction electrode, that is, the ion mass range is wider and the transmission efficiency is higher.

[0007] In one embodiment, the collision cell of the tandem mass spectrometer also includes a power supply module, which is used to provide DC1 direct current voltage, DC2 direct current voltage, DC3 direct current voltage and DC4 direct current voltage; the DC1 direct current voltage is applied to the introduction electrode, the DC2 direct current voltage is applied to the first segment of the front high-order field N-pole rod, the DC3 direct current voltage is applied to the tail segment of the front high-order field N-pole rod, and the DC4 direct current voltage is applied to the tail segment of the rear quadrupole rod.

[0008] In one embodiment, the power supply module is also used to provide two RF voltages with the same amplitude and opposite phases, namely, RF+ RF voltage and RF- RF voltage. The two RF voltages are connected to the ground with a first voltage-dividing capacitor C1, a second voltage-dividing capacitor C2 and a third voltage-dividing capacitor C3 connected in series in sequence. The wires between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 of the branch where the RF+ RF voltage is located are respectively electrically connected to the first segment of the front high-order field N-pole with a positive polarity, and the wires between the branch where the RF- RF voltage is located are respectively electrically connected to the first segment of the front high-order field N-pole with a positive polarity. The wires between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 are respectively electrically connected to the first segment of the front high-order field N-pole with a negative polarity, the wires between the first voltage-dividing capacitor C2 and the second voltage-dividing capacitor C3 in the branch where the RF+ radio frequency voltage is located are respectively electrically connected to the first segment of the rear quadrupole with a positive polarity, and the wires between the first voltage-dividing capacitor C2 and the second voltage-dividing capacitor C3 in the branch where the RF- radio frequency voltage is located are respectively electrically connected to the first segment of the rear quadrupole with a negative polarity.

[0009] In one of the embodiments, the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 are adjustable capacitors with adjustable sizes; the amplitude of the RF voltage is adjustable, and the amplitude of the DC voltage is adjustable.

[0010] In one embodiment, the first segment of the front high-order field N-pole rod is tilted relative to the central axis of the chamber, the field radius of the first segment of the front high-order field N-pole rod close to the end of the introduction electrode is R3, the field radius of the tail segment of the front high-order field N-pole rod away from the end of the introduction electrode is R1, and R3 is greater than R1.

[0011] In one of the embodiments, each segment from the second segment to the tail segment of the front high-order field N-pole is arranged parallel to the central axis of the chamber; the length of the first segment of the front high-order field N-pole is greater than the length of the remaining segments of the front high-order field N-pole.

[0012] In one of the embodiments, each segment of the front high-order field N-pole rod is tilted relative to the central axis of the chamber, and the field radius of the front high-order field N-pole rod gradually decreases along the central axis of the chamber.

[0013] In one embodiment, the field radius of the tail segment of the front high-order field N-pole rod away from the end of the introduction electrode is R1, and each segment of the rear quadrupole rod is arranged parallel to the central axis of the chamber, and the field radius of the rear quadrupole rod is R2, R1=R2.

[0014] A tandem mass spectrometer comprises a collision cell of the tandem mass spectrometer.

[0015] Compared with the traditional tandem mass spectrometer, the above-mentioned tandem mass spectrometer adopts the form of combining the front-stage high-order field N-pole and the rear-stage quadrupole and arranging them in the chamber in sequence along the central axis of the chamber, so that ions with a wider mass range can smoothly enter the front-stage high-order field N-pole after entering the chamber through the introduction center hole of the introduction electrode. The front-stage high-order field N-pole can capture ions with a wider mass range due to its relatively flat potential. In addition, the collision gas enters the chamber corresponding to the front-stage high-order field N-pole through the air vent, and the collision gas collides with the ions entering the front-stage high-order field N-pole, so that the ions are cracked to form fragments. The rear-stage quadrupole can realize the concentration of the fragmented fragments near the central axis, so that the focusing effect of the fragmented ions is better, and the fragments can efficiently pass through the extraction center hole of the extraction electrode, that is, the ion mass range is wider and the transmission efficiency is higher.

[0016] A working method of the tandem mass spectrometer includes the following steps: when the collision energy of ions entering the chamber needs to be adjusted, a DC1 direct current voltage is applied to the introduction electrode, and a DC2 direct current voltage is applied to the first segment of the front high-order field N-pole rod, and this is achieved by adjusting the magnitude of the DC1 direct current voltage.

[0017] The working method of the above-mentioned tandem mass spectrometer, on the one hand, has the technical effects brought by the above-mentioned tandem mass spectrometer due to the adoption of the above-mentioned tandem mass spectrometer; on the other hand, since the pressure difference between the DC1 direct voltage and the DC2 direct voltage can be changed by adjusting the magnitude of the DC1 direct voltage, the collision energy of the ions entering the chamber can be adjusted accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0020] Figure 1 A schematic diagram of the structure of a collision cell of a tandem mass spectrometer according to an embodiment of the present invention;

[0021] Figure 2 A schematic structural diagram of a collision cell of a tandem mass spectrometer according to another embodiment of the present invention;

[0022] Figure 3 A schematic structural diagram of a collision cell of a tandem mass spectrometer according to another embodiment of the present invention;

[0023] Figure 4 It is a schematic diagram of the structure of connecting the front section high-order field N-pole and the rear section quadrupole in the collision cell of the tandem mass spectrometer according to one embodiment of the present invention to the radio frequency power supply;

[0024] Figure 5 A spectrum collected by the collision cell of the tandem mass spectrometer according to an embodiment of the present invention when there is no collision energy;

[0025] Figure 6 A spectrum collected by a collision cell of a tandem mass spectrometer according to an embodiment of the present invention when the collision energy is, for example, 10 eV;

[0026] Figure 7 A spectrum collected by a collision cell of a tandem mass spectrometer according to an embodiment of the present invention when the collision energy is, for example, 30 eV;

[0027] Figure 8 A spectrum collected by a collision cell of a tandem mass spectrometer according to an embodiment of the present invention when the collision energy is, for example, 50 eV;

[0028] Fig. 9 This is a full information spectrum collected by the collision cell of the tandem mass spectrometer described in one embodiment of the present invention when the collision energy reaches 50 eV.

[0029] 10. Chamber; 11. Introducing electrode; 111. Introducing center hole; 12. Leading-out electrode; 121. Leading-out center hole; 13. Vent; 20. Front high-order field N-pole; 21. First segment; 30. Back quadrupole; 31. Second segment. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0031] See also Figure 1 , Figure 1 A schematic structural diagram of a collision cell of a tandem mass spectrometer according to an embodiment of the present invention is shown. An embodiment of the present invention provides a collision cell of a tandem mass spectrometer, and the collision cell of the tandem mass spectrometer includes: a chamber 10, a front-stage high-order field N-pole 20 and a rear-stage quadrupole 30.

[0032] An introduction electrode 11 is provided at the front end of the chamber 10. The introduction electrode 11 is provided with an introduction center hole 111, and an extraction electrode 12 is provided at the rear end of the chamber 10, and the extraction electrode 12 is provided with an extraction center hole 121. The front section high-order field N-pole 20 and the rear section quadrupole 30 are arranged in sequence along the central axis of the chamber 10, where N is an even number greater than 4. A vent 13 for introducing collision gas is provided at a portion of the side wall of the chamber 10 corresponding to the front section high-order field N-pole 20. Among them, the collision gas is an inert gas that does not react with ions, such as helium, nitrogen, argon, etc., which are not limited here.

[0033] The pole of the front section high-order field N-pole 20 includes more than two first segments 21 coaxially spaced in sequence, and a first insulating member (not shown in the figure) connected between two adjacent first segments 21. A first resistor and a first capacitor connected in parallel are connected in series between two adjacent first segments 21. The polarities of adjacent poles of the front section high-order field N-pole 20 are opposite. In addition, the pole of the rear section quadrupole 30 includes more than two second segments 31 coaxially spaced in sequence, and a second insulating member (not shown in the figure) connected between two adjacent second segments 31. A second resistor and a second capacitor connected in parallel are connected in series between two adjacent second segments 31, and the first segment of the rear section quadrupole 30 is connected to the first segment of the front section high-order field N-pole 20 through a third resistor.

[0034] It should be noted that N of the front-stage high-order field N-pole 20 is, for example, 6, 8, 10, etc., which is not limited here. In addition, the number of the first segments 21 of the front-stage high-order field N-pole 20 can be, for example, 2, 3, 4, 5, 6, etc., which is not limited here. In addition, the number of the second segments 31 of the rear-stage quadrupole 30 can be, for example, 2, 3, 4, 5, 6, etc., which is not limited here.

[0035] Compared with the collision cell of the conventional tandem mass spectrometer, the collision cell of the tandem mass spectrometer adopts the form that the front section high-order field N-pole 20 and the rear section quadrupole 30 are combined and arranged in the chamber 10 in sequence along the central axis of the chamber 10, so that after ions of a wider mass range enter the chamber 10 through the introduction center hole 111 of the introduction electrode 11, they can smoothly enter the front section high-order field N-pole 20. The front section high-order field N-pole 20 can capture the mass of the ions due to its relatively flat potential. The range is wider. In addition, the collision gas enters the position of the chamber 10 corresponding to the front high-order field N-pole 20 through the vent 13, and the collision gas collides with the ions entering the front high-order field N-pole 20, so that the ions are broken into fragments. The rear quadrupole 30 can concentrate the fragmented ions near the central axis after fragmentation, so that the focusing effect of the fragmented ions is better, and they can efficiently pass through the extraction center hole 121 of the extraction electrode 12, that is, a wider ion mass range and higher transmission efficiency can be achieved.

[0036] Please refer to Figure 1 Furthermore, the collision cell of the tandem mass spectrometer also includes a power module. The power module is used to provide DC1 direct voltage, DC2 direct voltage, DC3 direct voltage and DC4 direct voltage. The DC1 direct voltage is applied to the introduction electrode 11, and the DC2 direct voltage is applied to the first segment of the front high-order field N-pole 20. The DC3 direct voltage is applied to the tail segment of the front high-order field N-pole 20, and the DC4 direct voltage is applied to the tail end segment of the rear quadrupole 30. In this way, the electric field formed between the DC1 direct voltage and the DC2 direct voltage can adjust the collision kinetic energy of the incident ion accordingly by adjusting the voltage difference between the DC1 direct voltage and the DC2 direct voltage. The collision kinetic energy can be dynamically adjusted by means of program boosting, etc., which can not only make different analytes fragmented at their optimal collision energy, but also obtain the information of the parent ion when there is no collision energy, and the fragmentation information of the ion at low, medium and high collision kinetic energies.

[0037] Specifically, when the scanning speed of the tandem mass spectrometer is 50 spectra / s, the collision kinetic energy and the working time of various collision kinetic energies within 1S are set: the first 10 spectra are 0eV (0eV corresponds to no collision energy, and the corresponding spectrum collection time is, for example, 0 to 200ms), the next 10 spectra are 50eV (50eV corresponds to high collision energy, and the corresponding spectrum collection time is, for example, 800ms to 1000ms), and the middle 30 spectra are 10eV (10eV corresponds to low collision energy, and the corresponding spectrum collection is, for example, 200ms to 400ms) and 30eV (high collision energy, and the corresponding spectrum collection is, for example, 600ms to 800ms).

[0038] Further, see Figures 5 to 9 , Figures 5 to 9 The horizontal axis is expressed as mass-to-charge ratio (m / z). Figures 5 to 9 The vertical axis (y) represents the signal intensity.

[0039] See also Figure 5 , Figure 5 The diagram shows a spectrum collected by the collision cell of a tandem mass spectrometer in an embodiment of the present invention when there is no collision energy. At this time, the voltage difference between the DC1 direct voltage and the DC2 direct voltage from 0 to 200 ms is controlled to be 0 V, and the collected spectrum is the parent ion peak.

[0040] See also Figure 6 , Figure 6 The diagram shows a spectrum collected by the collision cell of a tandem mass spectrometer according to an embodiment of the present invention when the collision energy is, for example, 10 eV. At this time, the voltage difference between the DC1 direct voltage and the DC2 direct voltage from 200 ms to 400 ms is controlled to be 10 V, and the collected spectrum is a spectrum of fragment ions under low collision energy, which is rich in fragments.

[0041] See also Figure 7 , Figure 7 The diagram shows a spectrum collected by the collision cell of a tandem mass spectrometer according to an embodiment of the present invention when the collision energy is, for example, 30 eV. At this time, the voltage difference between the DC1 direct voltage and the DC2 direct voltage from 600 ms to 800 ms is controlled to be 30 V, and the collected spectrum is a spectrum of fragment ions at medium collision energy, which is rich in fragments.

[0042] See also Figure 8 , Figure 8 The diagram shows a spectrum collected by the collision cell of a tandem mass spectrometer according to an embodiment of the present invention when the collision energy is, for example, 50 eV. At this time, the voltage difference between the DC1 direct voltage and the DC2 direct voltage from 800 ms to 1000 ms is controlled to be 50 V, and the collected spectrum is a spectrum of fragment ions under high collision energy, which is rich in fragments.

[0043] See also Fig. 9 , Fig. 9 The full information spectrum collected by the collision cell of the tandem mass spectrometer of one embodiment of the present invention when the collision energy is less than 50 eV is shown. By superimposing the spectra collected within 1 s, the full information spectrum of the target ion can be obtained. This structure and implementation method can optimize and maximize the information collection of tandem mass spectrometry analysis.

[0044] Note: V volt is the unit of electric potential and voltage, and eV electron volt is the unit of energy. Since the amount of charge multiplied by the voltage has the dimension of energy E=qU, the change in electric potential energy corresponding to a change of 1V in the electric field for one unit of electron charge is defined as 1eV.

[0045] Specifically, when the collision energy is 0eV, for example, DC1=DC2=25V (25V is just an example, the specific value depends on the electrostatic DC voltage applied to the front and rear electrodes of the collision cell), DC3=20V~23V, DC4=13V~18V, which depends on the size of the ion mass-to-charge ratio, the size of the collision cell and other parameters, such as the field radii R1 and R2, the total length of the poles, etc. When the collision kinetic energy is 10eV, DC1=35V, DC2=25V, DC3=20V~23V, DC4=13V~18V; when the collision kinetic energy is 30eV, DC1=55V, DC2=25V, DC3=20V~23V, DC4=13V~18V; when the collision kinetic energy is 50eV, DC1=75V, DC2=25V, DC3=20V~23V, DC4=13V~18V; DC1 can use program boosting with a step size of 1V, rising from DC2 to the set voltage value, so that the collision energy changes linearly and dynamically, so that the best collision ability of the target ion can be judged according to the collected fragment peaks. In addition, specific values ​​can be set, corresponding to collision-free kinetic energy and low, medium and high collision energies, to obtain the parent ions and fragment ions of the target ions under different collision energies, and the spectra can be superimposed to obtain a full-information spectrum, so as to obtain more comprehensive and complete structural information, so as to optimize and maximize the information collection of tandem mass spectrometry analysis.

[0046] In addition, the voltage difference between the DC2 direct voltage and the DC3 direct voltage is, for example, 2V to 5V, which is relatively smaller than the voltage difference between the DC1 direct voltage and the DC2 direct voltage. The axial gradient electric field formed by the voltage difference between the DC2 direct voltage and the DC3 direct voltage on the front high-order field N-pole 20 is mainly used for the axial acceleration of the remaining parent ions and fragment ions to achieve the axial transmission of ions. Similarly, the voltage difference between the DC3 direct voltage and the DC4 direct voltage forms an axial gradient electric field on the rear quadrupole 30, which is used for the axial transmission of fragment ions in the rear quadrupole 30, shortening the time for the fragment ions to fly out of the collision cell, and can effectively reduce the residence time of ions in the high-pressure collision cell.

[0047] See also Figure 4 , Figure 4The schematic diagram of the structure of the front high-order field N-pole 20 and the rear quadrupole 30 in the collision cell of the tandem mass spectrometer of one embodiment of the present invention connected to the radio frequency power supply is shown. In one embodiment, the power supply module is also used to provide two radio frequency voltages with the same amplitude and opposite phases, namely RF+ radio frequency voltage and RF- radio frequency voltage. The first voltage-dividing capacitor C1, the second voltage-dividing capacitor C2 and the third voltage-dividing capacitor C3 connected in series are connected between the two radio frequency voltages and the ground. The wires between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 of the branch where the RF+ radio frequency voltage is located are respectively electrically connected to the first section with positive polarity of the front high-order field N-pole 20, the wires between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 of the branch where the RF- radio frequency voltage is located are respectively electrically connected to the first section with negative polarity of the front high-order field N-pole 20, the wires between the first voltage-dividing capacitor C2 and the second voltage-dividing capacitor C3 of the branch where the RF+ radio frequency voltage is located are respectively electrically connected to the first section with positive polarity of the rear quadrupole 30, and the wires between the first voltage-dividing capacitor C2 and the second voltage-dividing capacitor C3 of the branch where the RF- radio frequency voltage is located are respectively electrically connected to the first section with negative polarity of the rear quadrupole 30. In this way, by setting the proportional relationship between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2, the front-stage high-order field N-pole 20 and the rear-stage quadrupole 30 can be set to a preset proportional relationship, and one RF power supply can be used to simultaneously provide RF voltage to the front-stage high-order field N-pole 20 and the rear-stage quadrupole 30, so that the structure of the ion guiding transmission device is relatively simple, the overall volume is small, and the cost is low. Moreover, one RF power supply can simultaneously achieve the front-stage high-order field N-pole 20 and the rear-stage quadrupole 30 to meet the optimal transmission conditions (q=0.2~0.7, q is a parameter of RF AC intensity).

[0048] It should be noted that the central axis is a line connecting the center point of the lead-in central hole 111 and the center point of the lead-out central hole 121 , and is perpendicular to the lead-in electrode 11 and the lead-out electrode 12 , respectively.

[0049] It should be noted that the first segment with positive polarity of the front high-order field N-pole 20 refers to the first segment 21 with positive polarity in the front high-order field N-pole 20 close to the introduction electrode 11. The first segment with negative polarity of the front high-order field N-pole 20 refers to the first segment 21 with negative polarity in the front high-order field N-pole 20 close to the introduction electrode 11. Similarly, the first segment with positive polarity of the rear quadrupole 30 refers to the second segment 31 with positive polarity in the rear quadrupole 30 close to the introduction electrode 11. The first segment with negative polarity of the rear quadrupole 30 refers to the second segment 31 with negative polarity in the rear quadrupole 30 close to the introduction electrode 11.

[0050] It should be noted that the sizes of the first resistor, the second resistor and the third resistor may be the same or different, which is not limited here. In addition, the sizes of the first resistors of each adjacent first segment 21 may be the same or different, which is not limited here. In addition, the sizes of the second resistors of each adjacent second segment 31 may be the same or different, which is not limited here.

[0051] It should be noted that the sizes of the first capacitor and the second capacitor can be the same or different, which is not limited here. In addition, the sizes of the first capacitors of each adjacent first segment 21 can be the same or different, which is not limited here. In addition, the sizes of the second capacitors of each adjacent second segment 31 can be the same or different, which is not limited here.

[0052] In one embodiment, the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 are adjustable capacitors with adjustable sizes.

[0053] In one embodiment, the amplitude of the RF voltage is adjustable, and the amplitude of the DC voltage is adjustable.

[0054] See also Figure 2 or Figure 3 , Figure 2 FIG. 1 is a schematic diagram showing the structure of a collision cell of a tandem mass spectrometer according to another embodiment of the present invention. Figure 3 The schematic diagram of the structure of the collision cell of the tandem mass spectrometer of another embodiment of the present invention is illustrated. In one embodiment, the first segment of the front high-order field N-pole 20 is tilted relative to the central axis of the chamber 10, and the field radius of the first segment of the front high-order field N-pole 20 close to the end of the introduction electrode 11 is R3, and the field radius R3 refers to the radius of the inscribed circle of the end of each first segment of the front high-order field N-pole 20 close to the introduction electrode 11. The field radius of the tail segment of the front high-order field N-pole 20 away from the end of the introduction electrode 11 is R1, and the field radius R1 refers to the radius of the inscribed circle of the end of each tail segment of the front high-order field N-pole 20 away from the introduction electrode 11. Among them, R3 is greater than R1. In this way, it can be beneficial to capture more incident ions, and the mass range of the incident ions is wider. In addition, the DC2 DC voltage loaded on the first segment of the front high-order field N-pole 20 can not only provide axial acceleration kinetic energy for the ions, but also generate a radial component to focus the ions near the central axis of the chamber 10, thereby improving the ion transmission efficiency.

[0055] Please refer to Figure 2In one embodiment, each segment from the second segment to the tail segment of the front high-order field N-pole 20 is arranged parallel to the central axis of the chamber 10. In addition, the length of the first segment of the front high-order field N-pole 20 is greater than the length of the remaining segments of the front high-order field N-pole 20. In this way, when the length of the first segment of the front high-order field N-pole 20 is larger, it is more conducive to capturing more incident ions, and the mass range of the incident ions is wider. Of course, the length of the first segment of the front high-order field N-pole 20 can also be equal to or slightly smaller than the length of the remaining segments of the front high-order field N-pole 20, which is not limited here.

[0056] Please refer to Figure 3 In one embodiment, each segment of the front high-order field N-pole 20 is tilted relative to the central axis of the chamber 10, and the field radius of the front high-order field N-pole 20 gradually decreases along the central axis of the chamber 10. In addition, the DC voltage loaded on each segment of the front high-order field N-pole 20 can not only provide axial acceleration kinetic energy for the ions, but also generate a radial component to focus the ions near the central axis of the chamber 10, thereby improving the transmission efficiency of the ions.

[0057] It should be noted that the front-stage high-order field N-pole 20 is not limited to the first segment in the above embodiment being tilted relative to the central axis of the chamber 10, nor is it limited to each segment being tilted relative to the central axis of the chamber 10. The front-stage high-order field N-pole 20 may also be, for example, the first two, three, four or other number of segments being tilted relative to the central axis of the chamber 10, and the remaining segments being parallel to the central axis of the chamber 10.

[0058] It is also necessary to note that please refer to Figure 1 , each segment of the front high-order field N-pole rod 20 can also be arranged parallel to the central axis of the chamber 10.

[0059] In one embodiment, the field radius of the tail segment of the front high-order field N-pole 20 away from the end of the introduction electrode 11 is R1, and each segment of the rear quadrupole 30 is arranged parallel to the central axis of the chamber 10, and the field radius of the rear quadrupole 30 is R2, and the field radius R2 refers to the radius of the inscribed circle of each segment of the rear quadrupole 30. Wherein, R1=R2. In this way, the ions of the tail segment of the front high-order field N-pole 20 can be smoothly transitioned into the rear quadrupole 30.

[0060] In one embodiment, a tandem mass spectrometer includes the collision cell of the tandem mass spectrometer according to any one of the above embodiments.

[0061] Compared with the traditional tandem mass spectrometer, the above-mentioned tandem mass spectrometer adopts the form of combining the front-stage high-order field N-pole 20 and the rear-stage quadrupole 30 and sequentially arranging them in the chamber 10 along the central axis of the chamber 10, so that after ions with a wider mass range enter the chamber 10 through the introduction center hole 111 of the introduction electrode 11, they can smoothly enter the front-stage high-order field N-pole 20. The front-stage high-order field N-pole 20 can capture ions with a wider mass range due to its relatively flat potential. In addition, the collision gas enters the position of the chamber 10 corresponding to the front-stage high-order field N-pole 20 through the vent 13, and the collision gas collides with the ions entering the front-stage high-order field N-pole 20, so that the ions are cracked to form fragments. The rear-stage quadrupole 30 can realize the concentration of the fragmented fragments near the central axis, so that the focusing effect of the fragmented ions is better, and they pass through the extraction center hole 121 of the extraction electrode 12 efficiently, that is, the ion mass range is wider and the transmission efficiency is higher.

[0062] In one embodiment, a working method of the tandem mass spectrometer described in the above embodiment includes the following steps: when it is necessary to adjust the collision energy of ions entering the chamber, a DC1 direct current voltage is applied to the introduction electrode, and a DC2 direct current voltage is applied to the first segment of the front high-order field N-pole rod, and this is achieved by adjusting the magnitude of the DC1 direct current voltage.

[0063] The working method of the above-mentioned tandem mass spectrometer, on the one hand, has the technical effects brought by the above-mentioned tandem mass spectrometer because it adopts the above-mentioned tandem mass spectrometer; on the other hand, because the voltage difference between the DC1 direct voltage and the DC2 direct voltage can be changed by adjusting the magnitude of the DC1 direct voltage, the collision energy of the ions entering the chamber can be adjusted accordingly, that is, the collision kinetic energy of the incident ions can be adjusted accordingly. Not only can different analytes be fragmented at their optimal collision energy, but also the information of the parent ion when there is no collision energy, and the fragmentation information of the ions at low, medium and high collision kinetic energies (such as Figures 5 to 9 shown).

[0064] Specifically, the collision kinetic energy can be dynamically adjusted through programmed voltage boosting and other methods, that is, by gradually increasing the size of the DC1 direct voltage through programmed voltage boosting and other methods, the voltage difference between the DC1 direct voltage and the DC2 direct voltage can be linearly changed.

[0065] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0067] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0069] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0071] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

Claims

1. A collision cell for a tandem mass spectrometer, characterized in that: The collision cell of the tandem mass spectrometer comprises: A chamber, wherein the front end of the chamber is provided with an introduction electrode, the introduction electrode is provided with an introduction center hole, and the rear end of the chamber is provided with an extraction electrode, the extraction electrode is provided with an extraction center hole; A front section high-order field N-pole and a rear section quadrupole, wherein the front section high-order field N-pole and the rear section quadrupole are sequentially arranged along the central axis of the chamber, wherein N is an even number greater than 4, and a vent for introducing collision gas is provided at a position of the side wall of the chamber corresponding to the front section high-order field N-pole; The pole of the front section high-order field N-pole comprises two or more first segments coaxially spaced in sequence, and a first insulating member connected between two adjacent first segments, a first resistor and a first capacitor connected in parallel in series between two adjacent first segments, and the polarities of adjacent poles of the front section high-order field N-pole are opposite; The poles of the rear quadrupole include more than two second segments coaxially spaced in sequence, and a second insulating member connected between two adjacent second segments, a second resistor and a second capacitor connected in parallel are connected in series between two adjacent second segments, and the first segment of the rear quadrupole is connected to the first segment of the front high-order field N-pole through a third resistor.

2. The collision cell of the tandem mass spectrometer according to claim 1, characterized in that: The collision cell of the tandem mass spectrometer also includes a power supply module, which is used to provide DC1 direct current voltage, DC2 direct current voltage, DC3 direct current voltage and DC4 direct current voltage; the DC1 direct current voltage is applied to the introduction electrode, the DC2 direct current voltage is applied to the first segment of the front high-order field N-pole rod, the DC3 direct current voltage is applied to the tail segment of the front high-order field N-pole rod, and the DC4 direct current voltage is applied to the tail end segment of the rear quadrupole rod.

3. The collision cell of the tandem mass spectrometer according to claim 2, characterized in that: The power supply module is also used to provide two RF voltages with the same amplitude and opposite phases, namely, RF+ RF voltage and RF- RF voltage. A first voltage-dividing capacitor C1, a second voltage-dividing capacitor C2 and a third voltage-dividing capacitor C3 connected in series are connected between the two RF voltages and the ground. The wires between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 in the branch where the RF+ RF voltage is located are respectively electrically connected to the first section with positive polarity of the front high-order field N-pole, the wires between the first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 in the branch where the RF- RF voltage is located are respectively electrically connected to the first section with negative polarity of the front high-order field N-pole, the wires between the second voltage-dividing capacitor C2 and the third voltage-dividing capacitor C3 in the branch where the RF+ RF voltage is located are respectively electrically connected to the first section with positive polarity of the rear quadrupole, and the wires between the second voltage-dividing capacitor C2 and the third voltage-dividing capacitor C3 in the branch where the RF- RF voltage is located are respectively electrically connected to the first section with negative polarity of the rear quadrupole.

4. The collision cell of the tandem mass spectrometer according to claim 3, characterized in that: The first voltage-dividing capacitor C1 and the second voltage-dividing capacitor C2 are adjustable capacitors with adjustable sizes; the amplitude of the radio frequency voltage is adjustable, and the amplitude of the direct current voltage is adjustable.

5. The collision cell of the tandem mass spectrometer according to claim 2, characterized in that: The first segment of the front high-order field N-pole rod is tilted relative to the central axis of the chamber, the field radius of the first segment of the front high-order field N-pole rod close to the end of the introduction electrode is R3, and the field radius of the tail segment of the front high-order field N-pole rod away from the end of the introduction electrode is R1, and R3 is greater than R1.

6. The collision cell of the tandem mass spectrometer according to claim 5, characterized in that: Each segment from the second segment to the tail segment of the front high-order field N-pole is arranged parallel to the central axis of the chamber; the length of the first segment of the front high-order field N-pole is greater than the length of the remaining segments of the front high-order field N-pole.

7. The collision cell of the tandem mass spectrometer according to claim 5, characterized in that: Each segment of the front high-order field N-pole rod is tilted relative to the central axis of the chamber, and the field radius of the front high-order field N-pole rod gradually decreases along the central axis of the chamber.

8. The collision cell of a tandem mass spectrometer according to any one of claims 1 to 7, characterized in that: The field radius of the tail segment of the front high-order field N-pole away from one end of the introduction electrode is R1, and each segment of the rear quadrupole is arranged parallel to the central axis of the chamber, and the field radius of the rear quadrupole is R2, R1=R2.

9. A tandem mass spectrometer, characterized in that: A collision cell comprising a tandem mass spectrometer as claimed in any one of claims 1 to 8.

10. A method for operating a tandem mass spectrometer as claimed in claim 9, characterized in that: The method comprises the following steps: when the collision energy of ions entering the chamber needs to be adjusted, a DC1 direct voltage is applied to the introduction electrode, and a DC2 direct voltage is applied to the first segment of the front high-order field N-pole, which is achieved by adjusting the magnitude of the DC1 direct voltage.

Images