Quadrupole mass spectrometer capable of inhibiting interference of high-abundance ions on low-mass end

Abstract

The invention discloses a quadrupole mass spectrometer capable of inhibiting interference of high-abundance ions on a low mass end. The quadrupole mass spectrometer comprises an ion source, a quadrupole mass analyzer, a first power supply device, a second power supply device and a third power supply device, wherein the ion source comprises an ionization chamber and a filament assembly arranged at an electron inlet of the ionization chamber; the quadrupole rod mass analyzer is arranged at the downstream of the ion source; the first power supply device is connected with the filament assembly and used for providing first direct-current voltage capable of controlling electronic kinetic energy for the filament assembly. The second power supply device is connected with the quadrupole rod mass analyzer and is used for providing alternating voltage capable of scanning from low ion mass number to high ion mass number and second direct current voltage capable of controlling ion axial kinetic energy for the quadrupole rod mass analyzer; the third power supply device is connected with the ionization chamber and is used for providing third voltage capable of controlling electronic kinetic energy and ion kinetic energy for the ionization chamber; the third power supply device applies a first level and a second level to the ionization chamber in the low-quality scanning stage and the high-quality scanning stage respectively, and the first level is lower than the second level. According to the invention, the problem that the ion screening capability of the existing quadrupole mass spectrometer is lost due to the fact that the quadrupole scanning voltage approaches zero at the initial stage of mass scanning is effectively solved. According to the problem, a large number of high-abundance and high-quality ions pass through a quadrupole rod mass analyzer in a low-quality scanning interval and are detected by a detector, so that a strong interference peak is generated, a target signal is covered, instantaneous saturation of the detector is easily caused, and aging of the detector is accelerated.

Description

Technical Field

[0001] This invention relates to the field of mass spectrometry analysis technology, and more particularly to a quadrupole mass spectrometer that can suppress interference from high-abundance ions on the low-mass end. Background Technology

[0002] In quadrupole mass spectrometry, the high-abundance ion clusters detected at the beginning of the scan are often referred to as the "zero-mass peak." This peak appears in the mass spectrum at a position close to zero mass number, which can severely interfere with the detection of the true signal at the low-mass end, or even completely mask it, thus significantly affecting the accuracy and reliability of the analytical results.

[0003] As a core analytical instrument, the quadrupole mass spectrometer works by applying specific radio frequency and DC voltages to four parallel electrode rods to create a dynamically scanning quadrupole electric field, thereby achieving selective transport and screening of ions with different mass-to-charge ratios (m / z). A typical mass scan process starts with a lower voltage combination and increases linearly over time to achieve periodic scans from low mass numbers to high mass numbers.

[0004] However, existing quadrupole mass spectrometers generally suffer from severe signal distortion at the low-mass end. The root cause lies in the fact that at the start of the scan, both the radio frequency voltage and DC voltage are at extremely low levels, making it impossible to establish an effective dynamic barrier field within the quadrupole. At this point, the quadrupole loses its mass filtering capability and merely functions as a massless ion transport channel. All ions generated in the ionization source, regardless of their mass, can pass through the quadrupole unimpeded, forming a very strong signal interference peak in the low-mass region—the "zero-mass peak." This high-intensity interference peak triggers a series of chain-reaction negative effects, severely limiting the instrument's analytical performance, including: 1. The huge ion current corresponding to the interference peak far exceeds the detector's linear range, causing its output current to rapidly reach its upper limit and saturate. 1. The detector needs time to recover from saturation to the normal operating range. During this recovery period, the subsequent true low-mass ion signal will be severely suppressed, distorted, or even completely lost, leading to peak distortion and quantitative deviation. 2. The tailing effect of the interference peak significantly increases the baseline noise level in the low-mass region, causing the already weak low-abundance, low-mass target ion signal to be submerged in noise, greatly reducing the instrument's detection sensitivity at the low-mass end. 3. Continuous high-current surges will accelerate the aging of key components such as electron multipliers and shorten their service life. 4. This abnormal peak may be incorrectly identified by data processing software as a characteristic peak of an unknown compound, leading to incorrect qualitative results.

[0005] Currently, most technical solutions for quadrupole mass spectrometers that address the interference of high-abundance ions with low-mass signals during the initial scanning phase employ avoidance strategies, lacking an effective mechanism for actively blocking the ion flow at the ion source. For example, the tandem mass spectrometer and its usage method described in patent publication CN103582929A uses a dynamic scanning window strategy to mitigate the impact of interference regions. While this method alleviates signal distortion to some extent, it sacrifices effective scanning time, reducing overall analytical efficiency. More importantly, this approach does not suppress ion generation at the source and cannot control the quality of the ion flow entering the quadrupole. Untreated ions may accumulate in the ionization chamber, exacerbating the degradation of the low-mass signal and failing to fundamentally solve the systemic interference problem caused by the "zero-mass peak."

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] This invention aims to at least partially address one of the technical problems in related technologies. To this end, this invention proposes a quadrupole mass spectrometer that can suppress interference from high-abundance ions at the low-mass end. This mass spectrometer not only effectively suppresses the abnormal detection of high-mass ions at the low-mass end, significantly eliminates abnormal peaks at the low-mass end, improves the signal-to-noise ratio and dynamic range of low-mass ions, and effectively extends the detector's lifespan, but also ensures analytical sensitivity. Furthermore, it has the advantages of simple implementation, high reliability, low cost, and strong practicality.

[0008] The present invention provides a quadrupole mass spectrometer capable of suppressing interference from high-abundance ions on the low-mass end, comprising:

[0009] An ion source, comprising an ionization chamber and a filament assembly disposed at the electron inlet of the ionization chamber; and

[0010] Quadrupole mass analyzer, the quadrupole mass analyzer is located downstream of the ion source;

[0011] The filament assembly is connected to a first power supply device, which is configured to provide the filament assembly with a first DC voltage that can control electronic kinetic energy.

[0012] The quadrupole mass analyzer is connected to a second power supply device, which is configured to provide the quadrupole mass analyzer with an alternating voltage that can scan from low ion mass number to high ion mass number and a second DC voltage that can control the ion axial kinetic energy.

[0013] The ionization chamber is connected to a third power supply device, which is configured to provide the ionization chamber with a third voltage that allows for controllable electron kinetic energy and ion kinetic energy.

[0014] When the second power supply device applies an alternating voltage to the quadrupole mass analyzer, causing the ion mass number scanned by the quadrupole mass analyzer to be lower than the preset ion mass number, the third power supply device applies the first level of the third voltage to the ionization chamber.

[0015] When the second power supply device applies an alternating voltage to the quadrupole mass analyzer, causing the ion mass number scanned by the quadrupole mass analyzer to be higher than the preset ion mass number, the third power supply device applies a second level of the third voltage to the ionization chamber.

[0016] The first voltage level is lower than the second voltage level, and the timing period of the third voltage is synchronized with the quality scan period of the quadrupole quality analyzer.

[0017] This invention provides a quadrupole mass spectrometer capable of suppressing interference from high-abundance ions at the low-mass end. By utilizing the related settings and coordinated use of a first, second, and third power supply unit, and through the coordinated regulation of ion kinetic energy and electron kinetic energy at the ion source, it effectively suppresses the abnormal detection of high-mass ions at the low-mass end. Specifically, on the one hand, by applying a suppression voltage to the ionization chamber during the low-mass-number scan phase, the initial ionic velocity and electron kinetic energy are simultaneously reduced, thereby attenuating the high-mass-number ion transport intensity and suppressing its ionization efficiency, effectively reducing the generation of high-abundance, high-mass-number interfering ions. On the other hand, by restoring the normal operating voltage of the ionization chamber during the high-mass-number scan phase, analytical sensitivity is ensured. Furthermore, this invention requires no modification to the quadrupole structure or drive circuit, is simple to implement, low in cost, significantly eliminates abnormal peaks at the low-mass end, improves the signal-to-noise ratio and dynamic range of low-mass ions, and effectively extends the detector's lifespan.

[0018] The third power supply device applies a first level and a second level to the ionization chamber during the low-mass and high-mass scanning phases, respectively. This weakens the axial kinetic energy of ions during the low-mass scanning phase, lengthens the time ions spend moving in the quadrupole mass analyzer, and makes it easier for ions to follow the constraints of the Matthew equation. This achieves constraint on the ion current signal during the low-mass scanning phase from the ion source, solves the problem of abnormal peaks appearing at the low-mass end affecting the ion signal in the low-mass region, and addresses the interference of high-abundance ion clusters on the detector. This protects the mass spectrometry signal in the low-mass region and expands the detection range of the mass spectrometer.

[0019] In some embodiments, the preset ion mass number ranges from 0.5 amu to 5 amu.

[0020] In some embodiments, the voltage difference between the second level and the first level is one of 0V to 10V, 10V to 20V, 20V to 30V, 30V to 40V, and 40V to 100V.

[0021] In some embodiments, a non-mass scanning phase is included between adjacent cycles of the mass scanning cycle, and a third power supply device applies a third level of a third voltage to the ionization chamber, and the third level is lower than the second level.

[0022] In some embodiments, the voltage difference between the third level and the second level is one of 0V to 10V, 10V to 20V, 20V to 30V, 30V to 40V, and 40V to 100V.

[0023] In some embodiments, the ionization chamber includes a cubic ionization chamber body, the ionization chamber body having a through hole along a first direction, the through hole forming a sample inlet and an ion beam outlet on two surfaces of the ionization chamber body, respectively.

[0024] The ionization chamber body has four recesses on its four surfaces in the second and third directions for mounting filament assemblies, and each recess has an electron slit with a through hole.

[0025] Among them, the first direction, the second direction, and the third direction are perpendicular to each other in space.

[0026] In some embodiments, the filament assembly includes a filament arm, an electronic repulsion electrode, and a filament holder;

[0027] The electron repulsion electrode includes a first bent metal sheet and a second bent metal sheet. The first bent surface of the first bent metal sheet and the second bent metal sheet are attached together and detachably fixed to the upper part of the middle of the back of the filament holder. The second bent surface of the first bent metal sheet and the second bent metal sheet are parallel and spaced a certain distance apart and located on the upper part of the front of the filament holder.

[0028] The filament holder has symmetrical grooves on both sides of its front side, and two filament arms are detachably fixedly connected in the grooves; a filament is fixedly connected between the upper ends of the two filament arms, and the filament passes between the second bending surface of the first bent metal sheet and the second bending surface of the second bent metal sheet; one of the filament arms is connected to the electron repulsion electrode.

[0029] In some embodiments, the ion source further includes an off-axis electrostatic lens assembly disposed between the ionization chamber and the quadrupole mass analyzer, the off-axis electrostatic lens assembly including a first deflection lens group, a second deflection lens group and a third deflection lens group;

[0030] The first deflecting lens group is used to focus the ion beam injected from the ionization chamber along the central axis and deflect the ion beam in direction I; the second deflecting lens group is used to receive and focus the ion beam from the first deflecting lens group and deflect the ion beam in direction II; the third deflecting lens group is used to receive and focus the ion beam from the second deflecting lens group and deflect the ion beam in direction III, and direction III is substantially parallel to the central axis of the first deflecting lens.

[0031] In some embodiments, the quadrupole mass analyzer includes a quadrupole master rod and a quadrupole pre-rod disposed on the quadrupole master rod facing the ion source end; the quadrupole pre-rod is configured to focus the ion beam and introduce it into the quadrupole master rod, and the quadrupole master rod is configured to perform mass scanning and screening of the ion beam.

[0032] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a structural block diagram of the quadrupole mass spectrometer disclosed in this invention.

[0035] Figure 2 This is a timing diagram of the voltage output of the second and third power supply devices in the quadrupole mass spectrometer disclosed in this invention.

[0036] Figure 3 This is a mass spectrum showing the interference of abnormal peaks on the low-mass end in existing mass spectrometers.

[0037] Figure 4 This is the mass spectrum of the quadrupole mass spectrometer disclosed in this invention after eliminating abnormal peaks.

[0038] Figure 5 This is a decomposition diagram of the ion source in the quadrupole mass spectrometer disclosed in this invention.

[0039] Figure 6 This is a three-dimensional view of the ion chamber in the quadrupole mass spectrometer disclosed in this invention.

[0040] Figure 7-9 This is a schematic diagram of the filament assembly in the quadrupole mass spectrometer disclosed in this invention. Figure 7 Main view, Figure 8 This is the rear view. Figure 9 This is a side view.

[0041] Figure 10 This is a three-dimensional view of the filament arm in the quadrupole mass spectrometer disclosed in this invention.

[0042] Figure 11 This is a three-dimensional view of the electron repulsion electrode in the quadrupole mass spectrometer disclosed in this invention.

[0043] Figure 12 This is a perspective view of the filament holder in the quadrupole mass spectrometer disclosed in this invention.

[0044] Figure 13 This is a simulation diagram of the ion beam deflection trajectory of the off-axis electrostatic lens assembly in the quadrupole mass spectrometer disclosed in this invention.

[0045] Meaning of the labels in the attached diagram:

[0046] 1-Ion source;

[0047] 11-Ionization chamber;

[0048] 111-Ionization chamber body; 111-1-Through hole; 111-2-Recess; 111-2-1-Electron slit; 111-3-Fifth threaded hole; 111-3-1-Fifth screw; 111-4-Sixth threaded hole; 111-4-1-Sixth screw;

[0049] 112 - Third power supply unit;

[0050] 12-Filament assembly;

[0051] 121-Filament arm;

[0052] 1211-First filament arm; 1211-1-First threaded hole A; 1211-1-First nut screw; 1211-2-Second threaded hole A; 1211-2-1-Third screw; 1211-3-Third threaded hole A; 1211-3-1-First screw; 1211-4-First through hole A; 1211-5-Second through hole A.

[0053] 1212-Second filament arm; 1212-1-First threaded hole B; 1212-1-1-Second nut screw; 1212-2-Second threaded hole B; 1212-2-1-Fourth screw; 1212-3-Third threaded hole B; 1212-3-1-Second screw; 1212-4-First through hole B; 1212-5-Second through hole B.

[0054] 122-Electron repulsion electrode; 1221-First bent metal sheet; 1221-1-Third through hole A; 1222-Second bent metal sheet; 1222-1-Third through hole B;

[0055] 123-Filament holder; 123-1-First groove; 123-1-1-Fourth through hole A; 123-2-Second groove; 123-2-1-Fourth through hole B; 123-3-Fourth threaded hole; 1231-Lamp holder;

[0056] 124-Filament;

[0057] 125 - First power supply unit;

[0058] 13-Off-axis electrostatic lens assembly; 131-First deflecting lens group; 132-Second deflecting lens group; 133-Third deflecting lens group;

[0059] 14-ion repulsion;

[0060] 2- Quadrupole mass analyzer;

[0061] 21-Quadrupole main rod; 211-Quadrupole prestressing rod;

[0062] 22-Second power supply device;

[0063] 3-ion detector.

[0064] X - First direction; Y - Second direction; Z - Third direction. Detailed Implementation

[0065] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0066] Quadrupole mass spectrometers in related technologies lack a mechanism to actively block the ion flow at the ion source generation point, thus failing to truly solve the problem of interference and distortion caused by high-abundance ion clusters to the low-mass end signal during the initial scanning phase. This problem often results in a large number of high-abundance, high-quality ions passing through the quadrupole mass analyzer in the low-mass scanning region and being detected by the detector, thereby generating strong interference peaks. This not only masks the target signal but also easily causes instantaneous saturation of the detector, accelerating its aging.

[0067] In view of this, the embodiments of this application aim to provide a quadrupole mass spectrometer that can suppress the interference of high-abundance ions on the low-mass end. This quadrupole mass spectrometer utilizes a quadrupole mass analyzer equipped with a second power supply and an ionization chamber equipped with a third power supply to work in coordination. By applying a suppression voltage to the ionization chamber of the ion source during the low-mass scan phase of the quadrupole mass analyzer, the ion kinetic energy during this scan phase is weakened, the ion travel time in the quadrupole mass analyzer is lengthened, and the electron kinetic energy during this phase is reduced, thus lowering the ionization efficiency. In this process, under the same kinetic energy conditions, the larger the ion mass number, the smaller the initial velocity, and therefore the longer the ion travels in the quadrupole mass analyzer, the more radio frequency cycles it undergoes, and the lower the ion transport rate. This eliminates the interference of high-mass-number, high-abundance ions on the low-mass end and eliminates the influence of abnormal peaks on the low-mass mass spectrometry signal. Therefore, this invention effectively solves the problem of existing quadrupole mass spectrometers losing ion screening capability during the initial mass scan phase due to the quadrupole scanning voltage approaching zero, thus solving the aforementioned problem.

[0068] The following is based on Figures 1-13 The quadrupole mass spectrometer of the present invention, which can suppress interference from high-abundance ions on the low-mass end, is described in detail.

[0069] Please refer to Figure 1 The present invention provides a quadrupole mass spectrometer that can suppress interference from high-abundance ions to the low-mass end, comprising an ion source 1, a quadrupole mass analyzer 2, and an ion detector 3 arranged end to end. The quadrupole mass analyzer 2 is located downstream of the ion source 1, and the ion detector 3 is located at the output end of the quadrupole mass analyzer 2.

[0070] Continue to refer to Figure 1 In this embodiment of the invention, the ion source 1 may include an ionization chamber 11 and a filament assembly 12 disposed at the electron inlet of the ionization chamber 11; wherein the filament assembly 12 is connected to a first power supply device 125, the first power supply device 125 being configured to provide the filament assembly 12 with a first DC voltage that can control the electron kinetic energy.

[0071] Continue to refer to Figure 1In this embodiment of the invention, the ionization chamber 11 is connected to a third power supply device 112, which is configured to provide the ionization chamber 11 with a third voltage that controls the kinetic energy of electrons and ions. The specific implementation principle is as follows: a microcontroller controls a digital-to-analog converter to output a periodically changing step-like voltage signal; this signal is then amplified by a high-bandwidth analog amplifier circuit, ultimately generating a third voltage signal that meets specific amplitude and timing requirements. The ionization chamber 11 is the core area of ​​the ion source 1, and its function is to receive and confine the sample gas, causing the sample gas to collide with electrons emitted by the filament and become ionized. The ionization chamber 11 is not only the site of ion generation, but the electrostatic potential field established inside it also determines the initial kinetic energy and direction of motion of the newly formed ions, which is crucial for the subsequent ion transmission efficiency and energy focusing, and is a key link in controlling the kinetic energy of the ion beam. When the mass spectrometer is running, the voltages of all electrodes in the ion source 1 are static voltages. Changing the voltage of the ionization chamber 11 at this time will change the axial kinetic energy of the ions.

[0072] In practice, the kinetic energy of electrons emitted by the filament 124 is determined by the first DC voltage provided by the first power supply device 125 and the third voltage provided by the third power supply device 112 to the ionization chamber 11. Keeping the first DC voltage constant, the electron kinetic energy changes with the third voltage; thus, only the third voltage needs to be changed to simultaneously control both the ionic axial kinetic energy and the electron kinetic energy. The electron kinetic energy when the ionization chamber 11 is at the first level is lower than the electron kinetic energy when the ionization chamber 11 is at the second level.

[0073] Continue to refer to Figure 1 In this embodiment of the invention, the quadrupole mass analyzer 2 is connected to a second power supply device 22, which is configured to provide the quadrupole mass analyzer 2 with an alternating voltage that can scan from low ion mass number to high ion mass number and a second DC voltage that can control the axial kinetic energy of the ions.

[0074] In specific implementation, the second power supply device 22 provides alternating voltage to the quadrupole mass analyzer 2, enabling the quadrupole mass analyzer 2 to perform mass scanning and screening functions from low to high ion mass. More specifically, a typical method for implementing the alternating voltage of the second power supply device 22 is as follows: First, a high-stability high-frequency sinusoidal frequency source signal is generated by a direct digital frequency synthesizer, while a microcontroller controls a digital-to-analog converter to output a periodic envelope signal for amplitude scanning; the two are multiplied by an analog multiplier to synthesize a composite modulation signal with controlled amplitude and fixed frequency. This signal is then sent to a transformer-coupled resonant amplifier circuit for high-voltage amplification, ultimately generating a high-frequency, high-amplitude alternating voltage suitable for mass scanning.

[0075] The second DC voltage of the second power supply device 22 is typically a digitally controlled high-voltage DC power supply, or a microcontroller-driven digital-to-analog converter combined with a high-voltage analog amplifier circuit to achieve a precisely adjustable output. Finally, the alternating voltage and the DC voltage are coupled through a DC blocking capacitor and a low-pass network, and are applied together to the electrode pairs of the quadrupole to form the required driving quadrupole electric field.

[0076] Reference Figure 2 When the second power supply device 22 applies an alternating voltage to the quadrupole mass analyzer 2, causing the ion mass number scanned by the quadrupole mass analyzer 2 to be lower than the preset ion mass number, the third power supply device 112 applies the first level of the third voltage to the ionization chamber 11.

[0077] When the second power supply device 22 applies an alternating voltage to the quadrupole mass analyzer 2, causing the ion mass number scanned by the quadrupole mass analyzer 2 to be higher than the preset ion mass number, the third power supply device 112 applies a second level of the third voltage to the ionization chamber 11.

[0078] The first voltage level is lower than the second voltage level, and the timing period of the third voltage is synchronized with the quality scan period of the quadrupole quality analyzer 2.

[0079] More specifically, Figure 2 This diagram illustrates the timing of the quadrupole mass analyzer 2 scanning one cycle of alternating voltage and the output voltage of the third power supply device 112. The conical ripples in the diagram represent a complete scan cycle of the quadrupole mass analyzer 2. The timing divider line corresponds to the preset ion mass number, dividing the quadrupole scan cycle into a first scan stage and a second scan stage. The first scan stage (located at the small end of the conical ripples to the left of the timing divider line) corresponds to the low-mass scan stage of the quadrupole mass analyzer 2, and the second scan stage (located at the large end of the conical ripples to the right of the timing divider line) corresponds to the high-mass scan stage of the quadrupole mass analyzer 2. The horizontal line in the diagram represents the third voltage. With the timing divider line as the boundary, the voltage change of the third power supply device 112 corresponds to the first level and the second level, where the first level on the left is lower than the second level on the right. In use, the third power supply device 112 supplies the ionization chamber 11 with a first level during the timing of the first scanning phase. When the period timing reaches the timing division line and the timing of the second scanning phase begins, the voltage supplied to the ionization chamber 11 by the third power supply device 112 changes from the first level to the second level, and at the same time, the scanning phase transitions from low-quality scanning to high-quality scanning.

[0080] In specific implementation, the third power supply device 112 applies a first level and a second level to the ionization chamber 11 during the low-mass and high-mass scanning phases, respectively. This weakens the axial kinetic energy of ions during the low-mass scanning phase, lengthens the time ions spend moving in the quadrupole mass analyzer 2, and makes it easier for ions to follow the constraints of the Matthew equation. This achieves constraint on the ion current signal during the low-mass scanning phase from the ion source 1, solving the problem of abnormal peaks appearing at the low-mass end affecting the ion signal in the low-mass region, and the interference of high-abundance ion clusters on the detector. This protects the mass spectrometry signal in the low-mass region and expands the detection range of the mass spectrometer. The effects of this technology can be seen from... Figure 3 and Figure 4 Comparative verification:

[0081] Figure 3 This is a mass spectrum of high-abundance ion clusters interfering with the low-mass end in the existing technology. There is an abnormally high peak near the zero-mass end, which not only interferes with the mass spectrum signal at the low-mass end, but also affects the detector's lifetime and response. Figure 4 The mass spectrum after eliminating abnormal peaks using the embodiments of the present invention clearly shows the mass spectrum signal in the low-mass region, thus eliminating the interference of abnormal peaks on the signal in the low-mass region.

[0082] In a further preferred embodiment of the invention, the preset ion mass number can be in the range of 0.5 amu to 5 amu.

[0083] The low-mass scan and high-mass scan stages are distinguished by a preset ion mass. When the second power supply device 22 applies a voltage to the quadrupole mass analyzer 2, causing the quadrupole mass analyzer 2 to be in the low-mass scan stage, the third power supply device 112 applies a first level of the third voltage to the ionization chamber 11. When the second power supply device 22 applies a voltage to the quadrupole mass analyzer 2, causing the quadrupole mass analyzer 2 to be in the high-mass scan stage, the third power supply device 112 applies a second level of the third voltage to the ionization chamber 11.

[0084] More preferably, in this embodiment of the invention, the voltage difference between the second level and the first level is one of 0V~10V, 10V~20V, 20V~30V, 30V~40V, and 40V~100V.

[0085] In some embodiments of the present invention, a non-mass scanning phase is included between adjacent mass scanning cycles, and the third power supply device 112 applies a third voltage at a third level to the ionization chamber 11 during the non-mass scanning phase, and the third level is lower than the second level.

[0086] In practice, the third level can not only suppress the electron emission efficiency of the filament assembly and reduce the electron kinetic energy during the non-mass scanning phase, thereby effectively reducing the ionization efficiency and preventing a large number of ions from accumulating in the ionization chamber; it can also reduce the ion kinetic energy, suppressing them from reaching the detector through the quadrupole mass analyzer, and significantly extending the lifespan of the detector.

[0087] Furthermore, in this embodiment of the invention, the voltage difference between the third level and the second level is one of 0V~10V, 10V~20V, 20V~30V, 30V~40V, and 40V~100V.

[0088] For example, refer to Figure 5-6 In some embodiments of the present invention, the ionization chamber 11 may include a cubic ionization chamber body 111. The ionization chamber body 111 has a through hole 111-1 along the first direction X. The through hole 111-1 forms a sample inlet and an ion beam outlet on two surfaces of the ionization chamber body 111, respectively. The four surfaces of the ionization chamber body 111 located in the second direction Y and the third direction Z are respectively provided with recesses 111-2 for mounting the filament assembly 12. Each recess 111-2 has an electron slit 111-2-1 that connects to the through hole 111-1. The first direction X, the second direction Y, and the third direction Z are perpendicular to each other in space.

[0089] In practice, the through-hole 111-1 is where ions are generated. Sample gas enters the through-hole 111-1 and is ionized. The ion repulsion electrode 14 and the off-axis electrostatic lens assembly 13 are arranged along the first direction X and are respectively installed at the sample inlet and the ion beam outlet. In use, the neutral sample first enters the ionization chamber 11 through the through-hole 111-1 through the ion repulsion electrode, and after being ionized, it is output as an ion beam through the off-axis electrostatic lens assembly 13.

[0090] In this embodiment of the invention, the ion source 1 is provided with four sets of filament assemblies 12, that is, electron slits 111-2-1 are opened on at least four sides of the ionization chamber 11 to allow electrons from the filament assemblies 12 to pass through the slits and enter the ionization chamber 11. For example, the four filament assemblies 12 surround the four sides of the ionization chamber 11. One filament assembly 12 is fixed to the ionization chamber body 111 by the cooperation of the fifth screw 111-3-1, the sixth screw 111-4-1, the fifth threaded hole 111-3, and the sixth threaded hole 111-4. The other three filament assemblies 12 are also fixed to the ionization chamber body 111 in the same way. Each filament assembly 12 includes a filament 124, which emits electrons that enter the ionization chamber 11 through the slits.

[0091] In practice, electrons enter the through-hole 111-1 through the electron slit 111-2-1 to ionize the sample gas. The recess 111-2 allows the filament 124 to be closer to the through-hole 111-1, making it easier for electrons emitted by the filament 124 to pass through the slit and enter the through-hole 111-1. The multi-directionally incident electron beams intertwine within the ionization chamber 11, increasing the collision paths between electrons and sample gas molecules within the ionization chamber 11. This significantly improves ion generation efficiency and ionization uniformity, eliminating the ionization spatial inhomogeneity problem caused by traditional single-sided or double-sided electron incident, ensuring the generation of a stable and consistent ion beam, thereby improving the instrument's repeatability, quantitative accuracy, resolution, and overall instrument stability.

[0092] For example, refer to Figure 7-9 In some embodiments of the present invention, the filament assembly 12 may include a filament 124, a first filament arm 1211, a second filament arm 1212, an electron repulsion electrode 122, and a filament holder 123, wherein a first power supply device 125 is connected to the electron repulsion electrode 122.

[0093] The filament 124 is fixed to one end of the first filament arm 1211 and the second filament arm 1212, and the first filament arm 1211 and the second filament arm 1212 are respectively embedded in the left and right sides of the filament fixing frame; the electron repulsion electrode 122 is formed by stacking the first bent metal sheet 1221 and the second bent metal sheet 1222, with one bending surface of the two bent metal sheets being parallel and spaced a certain distance apart, and the other bending surface being stacked and fixed on the first or second filament arm 1212.

[0094] Preferably, in this embodiment, the filament holder 123 is made of one of ceramic, glass, and polyetheretherketone.

[0095] Specifically, refer to Figure 10 In this embodiment of the invention, the upper end face of the first filament arm 1211 is provided with a first threaded hole A1211-1, the lower end face is provided with a second threaded hole A1211-2, the upper side of the filament arm 121 is provided with a first through hole A1211-4, the middle part of the filament arm 121 is provided with a third threaded hole A1211-3, and the lower part of the filament arm 121 is provided with a second through hole A1211-5 that is perpendicularly connected to the second threaded hole A1211-2. Similarly, in this embodiment of the invention, the same parts of the second filament arm 1212 are provided with a first threaded hole B1212-1, a second threaded hole B1212-2, a first through hole B1212-4, a third threaded hole B1212-3, and a second through hole B1212-5.

[0096] Specifically, refer to Figure 11In the electronic repulsion electrode 122 of the invention embodiment, a third through hole A1221-1 is provided on one side of the first bent metal sheet 1221, and a third through hole B1222-1 is provided on one side of the second bent metal sheet 1222.

[0097] Specifically, refer to Figure 12 The filament holder 123 of the invention embodiment has a first groove 123-1 and a second groove 123-2 symmetrically provided on both sides of the front side. The bottom of the first groove 123-1 is provided with a fourth through hole A123-1-1, the bottom of the second groove 123-2 is provided with a fourth through hole B123-2-1, and the lower part of the middle of the filament holder 123 is provided with a fourth threaded hole 123-3 for connecting with the lamp holder 1231.

[0098] During assembly, the first bent metal sheet 1221 and the first bent surface of the stacked second bent metal sheet are attached together and detachably fixed to the upper part of the middle of the back side of the filament holder 123. The second bent surface of the stacked first bent metal sheet 1221 and the second bent metal sheet are parallel and spaced a certain distance apart, and located above the front side of the filament holder 123. The first filament arm 1211 and the second filament arm 1212 are detachably fixed to the first groove 123-1 and the second groove 123-2, respectively. The filament 124 is fixedly connected between the upper ends of the first filament arm 1211 and the second filament arm 1212, and the filament 124 passes between the second bent surface of the first bent metal sheet 1221 and the second bent surface of the second bent metal sheet. Each filament assembly 12 is mounted on the surface of the ionization chamber body 111 via a lamp holder 1231. The filament holder 123 is detachably fixed to the lower center of the back side of the lamp holder 1231, and the lamp holder 1231 is detachably fixed to the ionization chamber body 111.

[0099] More specifically, the third through hole A1221-1, the third through hole B1222-1, the fourth through hole A123-1-1, and the third threaded hole A1211-3 on the same side of the first filament arm 1211 are coaxial and are fixed together by the first screw 1211-3-1. The first bent metal piece 1221, the second bent metal piece 1222, the filament retainer 123, and the first filament arm 1211 are fixed together. On the other side, the second screw 1212-3-1 passes through the fourth through hole B123-2-1 and the third threaded hole B1212-3 to fix the filament retainer 123 and the second filament arm 1212 together.

[0100] The two ends of the filament 124 pass through the first through hole A1211-4 and the first through hole B1212-4, respectively, and are fixed to the first filament arm 1211 and the second filament arm 1212 by the first nut screw 1211-1-1 and the second nut screw 1212-1-1 through the first threaded hole A1211-1 and the first threaded hole B1212-1, respectively. The third screw 1211-2-1 and the fourth screw 1212-2-1 are respectively installed in the second threaded hole A1211-2 and the second threaded hole B1212-2 and extend toward the second through hole A1211-5 and the second through hole B1212-5, respectively.

[0101] The structural design of the filament assembly 12 in this embodiment of the invention enables convenient maintenance and replacement of all components of the filament assembly 12. When any component (such as the single-sided filament arm 121, the electronic repulsion electrode 122, the filament 124, etc.) is damaged or needs adjustment, it can be disassembled and replaced individually without discarding other intact components, which greatly reduces the cost and time of maintenance. It ensures the precise and stable relative position between the electronic repulsion electrode 122 and the filament, and at the same time provides a reliable connection method for the first power supply device 125 to connect to the electronic repulsion electrode 122.

[0102] For example, refer to Figure 1 In some embodiments of the present invention, the ion source 1 may further include an off-axis electrostatic lens assembly 13 disposed between the ionization chamber 11 and the quadrupole mass analyzer 2 for ion beam deflection. The off-axis electrostatic lens assembly 13 includes a first deflecting lens group 131, a second deflecting lens group 132, and a third deflecting lens group 133;

[0103] The first deflecting lens group 131 is used to focus the ion beam injected from the ionization chamber 11 along the central axis (i.e., the central axis of the first deflecting lens) and deflect the ion beam in direction I; the second deflecting lens group 132 is used to receive and focus the ion beam from the first deflecting lens group 131 and deflect the ion beam in direction II; the third deflecting lens group 133 is used to receive and focus the ion beam from the second deflecting lens group 132 and deflect the ion beam in direction III, and direction III is substantially parallel to the central axis of the first deflecting lens.

[0104] In practice, the off-axis electrostatic lens assembly 13 can focus the charged particle beam, remove neutral particle interference, and restore the initial motion direction of the ion beam to be consistent with the motion direction when entering the next ion beam debugging stage.

[0105] In use, ions are generated in the ionization chamber 11 and then enter the off-axis electrostatic lens assembly 13 as an ion beam, beginning to travel along... Figure 13The direction axis, represented by the dashed line, moves from the first deflecting lens group 131 toward the third deflecting lens group 133. When passing the first deflecting lens group 131, the ion beam particle trajectory is deflected for the first time. Subsequently, it undergoes multiple deflections after passing the second deflecting lens group 132 and the third deflecting lens group 133. Finally, after multiple deflections, the ion beam moves along the direction axis shown in the figure again.

[0106] For example, refer to Figure 1 In some embodiments of the present invention, the quadrupole mass analyzer 2 may include a quadrupole main rod 21 and a quadrupole pre-rod 211 disposed on the quadrupole main rod 21 facing the ion source 1; wherein, the quadrupole pre-rod 211 is configured to focus the ion beam and introduce it into the quadrupole main rod 21, and the quadrupole main rod 21 is configured to perform mass scanning and screening of the ion beam.

[0107] In practice, the design of the pre-rod structure can not only effectively focus the ion beam, but also greatly reduce the edge field effect, which is conducive to improving ion implantation efficiency and mass resolution.

[0108] By utilizing the configuration of a first power supply device, a second power supply device, and a third power supply device, and by directly intervening at the ion generation source, this invention can achieve at least the following technical effects:

[0109] 1) A suppression voltage was applied to the ionization chamber during the low mass number scan phase of the quadrupole mass analyzer, thereby effectively reducing the kinetic energy of both electrons and ions. As a result, on the one hand, the reduction in electron kinetic energy weakens the ionization efficiency, and on the other hand, the reduction in ion kinetic energy prolongs its flight time in the quadrupole mass analyzer.

[0110] 2) It effectively suppresses background noise in low mass number regions, significantly improves the discernibility of low abundance and weak ion signals in these regions, thereby greatly improving detection sensitivity and signal-to-noise ratio.

[0111] 3) It effectively mitigates the impact of instantaneous high-intensity ion current on the detector, which helps to significantly extend the lifespan of the detector.

[0112] 4) By synchronously controlling the kinetic energy of electrons and ions, the interference of high-abundance, high-quality ions on the low-mass-number detection region is effectively suppressed without sacrificing scanning speed and other key performance.

[0113] 5) No modifications are required to the mechanical structure or drive circuit of core components such as the quadrupole mass analyzer. It is easy to implement, highly reliable, and inexpensive, with good practicality and scalability.

[0114] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0115] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0116] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0117] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications and equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A quadrupole mass spectrometer capable of suppressing interference from high-abundance ions at the low-mass end, characterized in that, include: An ion source, the ion source including an ionization chamber and a filament assembly disposed at the electron inlet of the ionization chamber; as well as A quadrupole mass analyzer is located downstream of the ion source; The filament assembly is connected to a first power supply device, which is configured to provide the filament assembly with a first DC voltage that can control electronic kinetic energy. The quadrupole mass analyzer is connected to a second power supply device, which is configured to provide the quadrupole mass analyzer with an alternating voltage that can scan from low ion mass number to high ion mass number and a second DC voltage that can control the ion axial kinetic energy. The ionization chamber is connected to a third power supply device, which is configured to provide the ionization chamber with a third voltage that allows control over electron kinetic energy and ion kinetic energy. When the second power supply device applies an alternating voltage to the quadrupole mass analyzer, causing the ion mass number scanned by the quadrupole mass analyzer to be lower than a preset ion mass number, the third power supply device applies a first level of a third voltage to the ionization chamber. When the second power supply device applies an alternating voltage to the quadrupole mass analyzer, causing the ion mass number scanned by the quadrupole mass analyzer to be higher than the preset ion mass number, the third power supply device applies a second level of the third voltage to the ionization chamber. The first voltage level is lower than the second voltage level, and the timing period of the third voltage is synchronized with the quality scan period of the quadrupole mass analyzer.

2. A quadrupole mass spectrometer according to claim 1, characterized in that, The preset ion mass number ranges from 0.5 amu to 5 amu.

3. A quadrupole mass spectrometer according to claim 1, characterized in that, The voltage difference between the second level and the first level is one of 0V~10V, 10V~20V, 20V~30V, 30V~40V, and 40V~100V.

4. A quadrupole mass spectrometer according to claim 1, characterized in that, The adjacent cycles of the mass scanning cycle include a non-mass scanning phase, and the third power supply device applies a third voltage at a third level to the ionization chamber, and the third level is lower than the second level.

5. A quadrupole mass spectrometer according to claim 4, characterized in that, The voltage difference between the third level and the second level is one of 0V~10V, 10V~20V, 20V~30V, 30V~40V, and 40V~100V.

6. A quadrupole mass spectrometer according to claim 1, characterized in that, The ionization chamber includes a cubic ionization chamber body, and the ionization chamber body has a through hole along a first direction. The through hole forms a sample inlet and an ion beam outlet on two surfaces of the ionization chamber body, respectively. The ionization chamber body has four recesses on its four surfaces in the second and third directions for installing the filament assembly, and each recess has an electron slit that connects to the through hole. Wherein, the first direction, the second direction, and the third direction are mutually perpendicular in space.

7. A quadrupole mass spectrometer according to claim 6, characterized in that, The filament assembly includes a filament arm, an electronic repulsion electrode, and a filament holder; The electron repulsion electrode includes a first bent metal sheet and a second bent metal sheet. The first bent metal sheet and the second bent metal sheet are stacked together on a first bent surface and are detachably fixed to the upper part of the middle of the back of the filament holder. The first bent metal sheet and the second bent metal sheet are stacked on a second bent surface that are parallel to each other and spaced a certain distance apart and located on the upper part of the front of the filament holder. The filament holder has symmetrical grooves on both sides of its front side, and the two filament arms are detachably fixedly connected to the grooves respectively; a filament is fixedly connected between the upper ends of the two filament arms, and the filament passes between the second bending surface of the first bent metal sheet and the second bending surface of the second bent metal sheet; one of the filament arms is connected to the electron repulsion electrode.

8. A quadrupole mass spectrometer according to claim 1, characterized in that, The ion source also includes an off-axis electrostatic lens assembly disposed between the ionization chamber and the quadrupole mass analyzer, the off-axis electrostatic lens assembly including a first deflection lens group, a second deflection lens group and a third deflection lens group; The first deflecting lens group is used to focus the ion beam injected from the ionization chamber along the central axis and deflect the ion beam in direction I; the second deflecting lens group is used to receive and focus the ion beam from the first deflecting lens group and deflect the ion beam in direction II; the third deflecting lens group is used to receive and focus the ion beam from the second deflecting lens group and deflect the ion beam in direction III, and direction III is substantially parallel to the central axis of the first deflecting lens.

9. A quadrupole mass spectrometer according to claim 1, characterized in that, The quadrupole mass analyzer includes a quadrupole main rod and a quadrupole pre-rod disposed on the quadrupole main rod facing the ion source end; the quadrupole pre-rod is configured to focus the ion beam and introduce it into the quadrupole main rod, and the quadrupole main rod is configured to perform mass scanning and screening of the ion beam.

Images