A method of broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer

Abstract

The application discloses a method for widening the injection mass range of a linear ion trap / time-of-flight mass spectrometer, and discloses a linear ion trap / time-of-flight mass spectrometer, which widens the external ion injection mass range of the linear ion trap / time-of-flight mass spectrometer through a segmented multi-stage rod, a bias voltage and a step trapping voltage strategy; when external ions are injected, only ions within a certain mass range can reach a mass spectrometer detector due to the difference in the movement speed of light ions and heavy ions, and the limited mass range seriously limits the analysis performance of the linear ion trap / time-of-flight mass spectrometer; the segmented multi-stage rod, the bias voltage and the step trapping voltage strategy can widen the mass range of the linear ion trap / time-of-flight mass spectrometer to which external ions are injected.

Description

Technical Field

[0001] The invention belongs to a mass spectrometry instrument, and in particular relates to a method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer. Background Art

[0002] Ion storage technology refers to storing ions outside the mass analyzer and then injecting ions immediately after the previous data acquisition / processing cycle is completed. In theory, it can increase the duty cycle of the continuous ion source to 100%. Among them, ion traps with ion storage function are the first choice for pre-stage storage devices of time-of-flight mass spectrometry (TOFMS). Therefore, ion trap time-of-flight tandem mass spectrometry (QIT / TOFMS) has been greatly developed. Compared with the point distribution state of three-dimensional ion traps, two-dimensional linear ion traps (LIT) have higher injection efficiency and higher ion storage capacity, and LIT / TOFMS has been greatly developed. However, when external ions are injected, due to the difference in migration speed of light and heavy ions, only ions within a certain mass range can reach the TOF pulse repulsion zone. The mass window problem of LIT / TOF seriously limits its application prospects.

[0003] LIT / TOF systems can be divided into two categories based on their serial coupling. One type uses the LIT only as a pre-stage storage device, interrupting the originally continuous ion flow and modulating it into ion clusters synchronized with the TOFMS. These ion clusters are then extracted into the TOFMS acceleration region for mass analysis. This is known as "orthogonal-coupled LIT / TOFMS." The other type uses the LIT as the delayed acceleration region of the TOFMS, known as "axially coupled LIT / TOFMS." Axially coupled LIT / TOFMS uses an ion trap as the repulsive acceleration region of the TOFMS, offering numerous advantages over radial coupling. However, in axially coupled LIT / TOFMS, the LIT acts as both an ion injection trap and a pulse delay region, impacting not only the external ion injection mass range but also the TOFMS resolution. To achieve high resolution, the LIT length must be sufficiently short to ensure high extraction electric field strength and uniformity, but this limits the ion injection mass range. Improving the injection mass window of axially coupled LIT / TOFMS without compromising resolution is crucial. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention discloses a method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer, wherein the linear ion trap / time-of-flight mass spectrometer comprises an external ion source, a segmented multipole rod, a linear ion trap, and a time-of-flight mass spectrometer coaxially arranged in sequence, wherein the segmented multipole rod comprises an entrance electrode, a segmented radio frequency electrode, an exit electrode, and a grid, wherein the segmented radio frequency electrode comprises a plurality of sub-electrode groups arranged in sequence, wherein a first group of electrodes and a secondary end electrode group of the segmented radio frequency electrode are divided by a resistor chain to form a uniform axial DC electric field, the linear ion trap comprises a front cover electrode, a radio frequency electrode, and a rear cover electrode, wherein the radio frequency electrode is applied with a radio frequency voltage and a DC bias voltage, and the front cover electrode and the rear cover electrode are applied with a DC voltage, and the voltages of the exit electrode, the front cover electrode, the radio frequency electrode, and the rear cover electrode are sequentially controlled to regulate the pre-enrichment, injection, capture, cooling, and extraction processes of ions within a wide mass range, specifically comprising the following methods:

[0005] Pre-enrichment period: Ions generated by the external ion source enter the segmented multi-pole rod under the action of the axial DC electric field. The DC voltage of the last group of segmented RF electrodes is set to zero potential, and the exit electrode is set to a high level to block ions, so that the ions are pre-enriched at the end of the segmented multi-pole rod. By tuning the electrode length and the exit electrode voltage, the ion injection path is shortened and the mass window is improved;

[0006] Injection phase: reduce the exit electrode voltage, front cover electrode voltage and RF electrode bias voltage to form an axial injection electric field, while raising the rear cover electrode to block ions, and improve the mass window by tuning the RF electrode bias voltage;

[0007] Capture period: After the injection period, the ions reach a certain position in the linear ion trap. The RF electrode bias voltage is reduced to zero. At the same time, the front cover electrode voltage and the rear cover electrode voltage are increased to the same high trapping potential. The axial potential barrier is increased to axially trap the ions. The mass window is improved by tuning the trapping potential.

[0008] Cooling period: After the capture period, the voltage of the front cover electrode and the rear cover electrode are immediately reduced to a low trapping potential to reduce the electric field penetration effect and ensure radial capture stability;

[0009] Extraction phase: After the ions have cooled sufficiently in the linear ion trap, the driving RF voltage of the RF electrode is turned off, and a double pulse voltage is applied to the front cover electrode voltage and the rear cover electrode at the same time to extract the ions from the linear ion trap to the time-of-flight mass analyzer.

[0010] Furthermore, the segmented multi-stage rod is used for pre-enrichment of ions.

[0011] Furthermore, the linear ion trap serves as a cooling device and a time-of-flight mass spectrometry delay zone.

[0012] Furthermore, the gas pressure in the ion trap ranges from 0.1 Pa to 100 Pa.

[0013] Furthermore, the pre-enrichment period has a time range of 0.5-20 ms, the injection period has a time range of 0.5-100 μs, the capture period has a time range of 0-50 μs, the cooling period has a time range of 0.5-20 ms, and the extraction period has a time range of 5-50 μs.

[0014] Furthermore, the length of the linear ion trap is in the range of 2-10 mm, the length of the last group of segmented electrodes of the segmented multipole is in the range of 2-10 mm, and the distance between the segmented multipole and the linear ion trap is in the range of 0.5-10 mm.

[0015] Furthermore, during the pre-enrichment period, the potential of the outlet electrode is higher than the zero potential, with an amplitude range of 1-100V; during the injection period, the bias potentials of the outlet electrode, the front cover electrode and the radio frequency electrode are lower than the zero potential, forming an axial potential gradient in sequence, with an amplitude range of 0-100V, and the potential of the rear cover electrode is higher than the zero potential, with an amplitude range of 0-100V; during the capture period, the high trapping potentials of the front cover and rear cover electrodes are higher than the zero potential, with an amplitude range of 1-200V; during the cooling period, the low trapping potentials of the front cover and rear cover electrodes are higher than the zero potential, with an amplitude range of 1-100V.

[0016] Furthermore, the grid is closely attached to the outlet electrode and is used to shield the electric field of the front cover electrode.

[0017] Furthermore, the external ion source includes various types of ion sources at normal pressure and negative pressure.

[0018] Furthermore, the linear ion trap ion extraction method is axial extraction.

[0019] Due to the adoption of the above-mentioned technical scheme, the present invention provides a method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer. First, an axially coupled linear ion trap / time-of-flight mass spectrometer is provided. The external ion injection mass range of the linear ion trap / time-of-flight mass spectrometer is broadened by using a segmented multi-pole rod, bias voltage and step-trapping voltage strategy. When external ions are injected, due to the difference in movement speed of light and heavy ions, only ions within a certain mass range can reach the mass spectrometer detector. The limited mass range seriously limits the analytical performance of the linear ion trap / time-of-flight mass spectrometer. The segmented multi-pole rod, bias voltage and step-trapping voltage strategy can broaden the mass range of the external ion injection linear ion trap / time-of-flight mass spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative effort based on these drawings.

[0021] Figure 1 The schematic diagram of the axial coupling LIT / TOF MS structure.

[0022] Figure 2 (a) is the working timing diagram of LIT / TOF MS; (b) is the axial potential distribution diagram in the pre-enrichment, injection, trapping and cooling stages.

[0023] Figure 3 The SIMION simulation model diagram of the primary trap: (a) is a 16.8 mm end-segmented short rod; (b) is a 4 mm end-segmented short rod; (c) is the central axial potential diagram in the cooling stage.

[0024] Figure 4 In the inter-trap extraction stage, (a) is the central axial potential distribution diagram; (b) is the axial motion trajectory diagram of the same m / z 200 ion under the conditions of bias voltage setting 0 V and -10 V.

[0025] Figure 5 (a) is the injection efficiency of m / z 50, 75 and 100 ions under the conditions of injection time 4 μs and bias voltage 0 V and -10 V; (b) is the injection efficiency of m / z 150, 175 and 200 ions under the conditions of injection time 9 μs and bias voltage 0 V and -10 V.

[0026] Figure 6 In the inter-trap extraction and cooling stage, (a) is the axial motion trajectory diagram of m / z 1000 ions with different kinetic energies under the condition of no step trapping potential; (b) is the central axial potential distribution diagram under the conditions of trapping potential 15 V and 30 V; (c) is the axial motion trajectory diagram of high kinetic energy m / z 1000 ions under the step trapping potential strategy under the conditions of bias voltage 0 V and -10 V.

[0027] Figure 7 (a) is the injection efficiency of m / z 250, 300 and 350 ions under the conditions of injection time 4 μs and with / without step trapping potential; (b) is the injection efficiency of m / z 1200, 1300, 1400 and 1500 ions under the conditions of injection time 9 μs and with / without step trapping potential.

[0028] Figure 8The ion injection efficiency changes with m / z under the conditions of segmented multi-stage rod, bias voltage and stepped trapping voltage strategy: (a) is the injection time of 4μs, and (b) is the injection time of 9μs.

[0029] Figure 9 (a) The variation of ion intensities of m / z 78, 106, 166, and 260 with extraction time between double wells under conditions with and without segmented multi-stage rods, bias voltage, and stepped trapping voltage strategy; (b) The mass spectrum when the relative intensity of m / z 106 is 1. DETAILED DESCRIPTION

[0030] To make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0031] The present invention discloses a method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer. The external ion injection mass range affects the analytical performance of the linear ion trap / time-of-flight mass spectrometer. By using a segmented multipolar rod, bias voltage, and stepped trapping voltage strategy, the external ion injection mass range of the linear ion trap / time-of-flight mass spectrometer can be broadened.

[0032] like Figure 1 In this example, the segmented multipole (LIT-1) is a segmented linear quadrupole structure, the injection ion trap (LIT-2) is a quadrupole structure, and the mass analyzer is a reflectron time-of-flight mass analyzer (TOFMS). The three are coaxially arranged. The segmented multipole is used for ion preconcentration and consists of an entrance electrode, a segmented electrode, and an exit electrode (IG1). The segmented electrodes are composed of four parallel electrode arrays (E1 to E12); each electrode array consists of concentric cylindrical electrodes evenly spaced apart. A DC voltage is applied to both the entrance and exit electrodes. Except for the last electrode (E12), the concentric cylindrical electrodes of the segmented electrodes are uniformly divided by a voltage divider resistor, forming an axial potential field to shorten the external ion injection path. Each cylindrical electrode is connected to a 1nF capacitor for applying a periodic radio frequency voltage. The injection ion trap serves as a secondary storage trap and TOF pulse delay zone and consists of a front cover electrode (IG2), a radio frequency electrode, and a rear cover electrode (IG3). A DC voltage is applied to both the front and rear cover electrodes. The RF electrode applies RF voltage and adds a DC bias voltage Q dc The LIT-2 not only serves as a secondary storage well but also as a delay zone for the TOF pulse. To maintain TOFMS resolution, the LIT-2 must be short to ensure the intensity and uniformity of the pulse extraction electric field, thus improving TOFMS resolution. The LIT-2 is 8 mm long.

[0033] Working sequence as Figure 2As shown in a, after the analyte is ionized by an external ionization source, a continuous or pulsed ion flow is obtained, which is carried to LIT-1 by the carrier gas. There is a uniform axial electric field between E1 and E11. The voltage of the last segmented electrode (E12) is set to 0V, and the voltage of IG1 is raised to a high potential to trap ions in LIT-1, achieving pre-cooling and pre-enrichment of the ion beam, while regulating the ion injection path; then the voltages of IG1 and IG2 are lowered and the voltage of IG3 is raised to complete the ion injection from LIT-1 to LIT-2; the voltages of IG1, IG2 and IG3 are raised to restore LIT-1 to the pre-enrichment state, and LIT-2 enters the capture and cooling stage; after the ion beam is fully cooled in LIT-2, positive and negative double pulse high voltages are applied to IG1 and IG2, respectively, to extract ions from LIT-2 to TOFMS. Figure 2 As shown in b, in the pre-enrichment stage, the LIT-1 ion enrichment site is z 0 ; When the ions are transferred from the pre-enrichment stage to the injection stage, the ions are transferred from z 0 It starts moving and reaches a certain position z in LIT-2. The extraction distance is divided into two parts s1 and s2 by Gate2. The ion m / ze first accelerates in a straight line motion, the motion path is s1, and then decelerates in a straight line motion, the motion path is s2. Ignoring the initial kinetic energy of the ion, the farthest axial position of the ion is z 0 equipotential point z max , the maximum displacement is s2 max The injection phase is set to time T set For the widest mass window, the smallest mass-to-charge ratio ion (m / ze) min Return to IG2, maximum mass-to-charge ratio ion (m / ze) max Just reached IG2, ratio (m / ze) max / (m / ze) min As shown below, by shortening path s1 and lengthening path s2, (m / ze) can be increased. max / (m / ze) min Among them, s1 and s2 depend on the structural design and voltage tuning strategy.

[0034]

[0035] Segmented multi-stage rod shortens the ion injection path: ion pre-enrichment site z in LIT 0 The position of z depends on the length of the LIT-1 end segment rod (E12), the voltage of the second end segment rod (E11) and the voltage of the ion gate (IG1). By shortening the length of E12, the z 0 Close to the end of the first-stage ion trap. Figure 2 As shown, Figure 2 The length of E12 in a is 16.8 mm. When the secondary terminal electrode voltage is 20 V, the path s1 is 9.4 mm. Figure 2 In b, the length of E12 is 4 mm, and the voltage of the secondary end electrode is set to 20 V, which can effectively move the cooling point z 0 , shortening the extraction path s1 to 3 mm.

[0036] Bias voltage expands the low m / z range: Low mass ions are easily affected by the electric field. During the injection phase, when the DC component of the RF voltage on the RF electrode is 0V, the injection depth s2 is insufficient due to the obstruction of the reverse electric field, and the transmission efficiency of low m / z ions is limited. Figure 3 As shown in a, during the injection phase, a bias voltage Q is applied to the LIT-2 RF electrode. dc = -10V, the axial injection depth s2 of the ions increases, which is beneficial to the expansion of the low-mass range. Figure 3 As shown in Figure b, the trajectory of an ion with m / z 200 is simulated and recorded under the bias potential of 0V and -10V. dc =-10V, ion injection path s2 max The increase of ~3.4mm enables efficient extraction of ions with m / z 200. Using SIMION simulation, the injection efficiency of ions in the low and high m / z ranges was investigated under injection times of 4μs and 9μs, respectively. Figure 4 As shown in the figure, when the bias voltage is set to -10 V during inter-trap ion transmission, the injection efficiency of m / z 50, 75, and 100 in the low mass range increases from 3.5%, 28%, and 58.5% to 11.5%, 64.5%, and 78%, respectively. In the high mass range, the injection efficiency of m / z 150, 175, and 200 increases from 9.5%, 16.5%, and 18% to 26%, 81.5%, and 91.5%, respectively.

[0037] Stepped trapping voltage increases the high m / z range: When the injection period ends, the ion reaches a certain position z in LIT-2, and when the potential difference between its position z and IG3 is greater than its kinetic energy E k , it can be captured, otherwise the ions will overshoot IG3 and be lost. And the higher the m / z, the greater the inertia, the easier it is to overshoot and lose. In order to improve the injection efficiency of high kinetic energy ions, it is necessary to increase the voltage of IG2 and IG3 during the capture period to increase the axial potential well depth and improve the ion capture efficiency. Take two m / z 1000 ions with different energies as an example. At the end of the injection period, the two ions reach z = 56.9 mm, where the axial potential barrier is 5.74 eV and the ion kinetic energy E k 4.1eV and 7.2eV respectively. Figure 5As shown in a, low energy ions 4.1eV < 5.74eV are captured; high energy ions 7.2eV > 5.74eV are lost due to ion overshoot. To capture high energy m / z 1000 ions, a high axial potential well depth is required, that is, increasing the voltages of IG2 and IG3. Figure 5 As shown in Figure b, by increasing the IG2 and IG3 voltages to 30V, the axial potential barrier increases to 11.5eV, which is higher than the kinetic energy 7.2eV, which can effectively prevent ion overshoot and achieve ion axial capture. However, when the IG2 and IG3 voltages are high, the electric field penetration effect will change the quadrupole field, making it impossible to achieve radial stable capture. Therefore, after achieving axial capture at a high voltage of 30V, it is necessary to immediately reduce the IG2 and IG3 voltages to 15V to ensure radial stable trapping. Figure 5 As shown in Figure 2, 7.2 eV high-energy ions were successfully implanted into LIT-2 through a stepped trapping voltage strategy.

[0038] Using SIMION simulation, the transmission efficiency of ions in the low and high m / z ranges was investigated under injection times of 4μs and 9μs, respectively. Figure 6 As shown in the figure, by using the stepped trapping voltage strategy, the transmission efficiency at m / z 250, 300, and 350 in the low m / z range increased from 36%, 9%, and 0.5% to 93%, 65.5%, and 25.5%, respectively. In the high mass range, the transmission efficiency at m / z 1200, 1300, 1400, and 1500 increased from 56.5%, 28%, 7.5%, and 7.5% to 99.5%, 94.5%, 91%, and 72%, respectively.

[0039] Mass range simulation results: The quality window of the cascade structure is investigated using three strategies: pre-stage segmented injection well, bias voltage, and step-trapping voltage. Figure 7 As shown, in the high m / z range, an injection efficiency of ∼100% was achieved in the range of m / z 200 to 1400. In the low m / z range, an injection efficiency of >60% was achieved in the range of m / z 75 to 300.

[0040] Mass range experimental results: The injection mass range was investigated using 10ppbv acetone, benzene, p-xylene, tetrachloroethylene, and 1,3-hexachlorobutadiene / nitrogen standard gases. Figure 8 and Figure 9 As shown in the figure, when the relative intensity of the m / z 106 ion signal is 100%, the old system cannot detect the m / z 260 ion. Under the new system, the relative signal intensity of m / z 260 reaches 0.25, and the relative signal intensity of m / z 166 is enhanced to 1.0.

[0041] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer, characterized by: The linear ion trap / time-of-flight mass spectrometer comprises an external ion source, a segmented multipole, a linear ion trap, and a time-of-flight mass spectrometer coaxially arranged in sequence, wherein the segmented multipole comprises an entrance electrode (1), a segmented radio frequency electrode (2), an exit electrode (4), and a grid (5), wherein the segmented radio frequency electrode (2) comprises a plurality of sub-electrode groups arranged in sequence, wherein the first group of electrodes and the secondary end electrode group of the segmented radio frequency electrode (2) form a uniform axial DC electric field by voltage division by a resistor chain, and the linear ion trap comprises a front cover electrode (6), a radio frequency electrode (7), and a rear cover electrode (8), wherein the radio frequency electrode (7) applies a radio frequency voltage and a DC bias voltage, and the front cover electrode (6) and the rear cover electrode (8) apply a DC voltage, and the voltages of the exit electrode (4), the front cover electrode (6), the radio frequency electrode (7), and the rear cover electrode (8) are sequentially controlled to regulate the pre-enrichment, injection, capture, cooling, and extraction processes of ions within a wide mass range, specifically including the following methods: Pre-enrichment period: ions generated by the external ion source enter the segmented multi-pole rod under the action of the axial DC electric field, the DC voltage of the last group of segmented electrodes (3) of the segmented radio frequency electrode (2) is set to zero potential, and the exit electrode (4) is set to a high level to block ions, so that the ions are pre-enriched at the end of the segmented multi-pole rod. By tuning the length of the electrode (3) and the voltage of the exit electrode (4), the ion injection path is shortened and the mass window is improved; Injection period: reduce the voltage of the outlet electrode (4), the voltage of the front cover electrode (6) and the bias voltage of the radio frequency electrode (7) to form an axial injection electric field, and at the same time raise the rear cover electrode (8) to block ions, and improve the mass window by tuning the bias voltage of the radio frequency electrode (7); Capture period: After the injection period, the ions reach a certain position in the linear ion trap, the bias voltage of the radio frequency electrode (7) is reduced to zero, and at the same time, the voltage of the front cover electrode (6) and the rear cover electrode (8) are increased to the same high trapping potential, thereby increasing the axial potential barrier to axially trap the ions, and improving the mass window by tuning the trapping potential; Cooling period: After the capture period, the voltage of the front cover electrode (6) and the rear cover electrode (8) are immediately reduced to a low trapping potential to reduce the electric field penetration effect and ensure radial capture stability; Extraction phase: After the ions are sufficiently cooled in the linear ion trap, the driving RF voltage of the RF electrode (7) is turned off, and a double pulse voltage is applied to the front cover electrode (6) and the rear cover electrode (8) at the same time to extract the ions from the linear ion trap to the time-of-flight mass analyzer.

2. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The segmented multipolar rod is used for pre-enrichment of ions.

3. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The linear ion trap serves as a cooling device and a time-of-flight mass spectrometer delay zone.

4. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The gas pressure in the ion trap ranges from 0.1 Pa to 100 Pa.

5. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The pre-enrichment period has a time range of 0.5-20 ms, the injection period has a time range of 0.5-100 μs, the capture period has a time range of 0-50 μs, the cooling period has a time range of 0.5-20 ms, and the extraction period has a time range of 5-50 μs.

6. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The length of the linear ion trap is in the range of 2-10 mm, the length of the last group of segmented electrodes of the segmented multipole is in the range of 2-10 mm, and the distance between the segmented multipole and the linear ion trap is in the range of 0.5-10 mm.

7. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: During the pre-enrichment period, the potential of the outlet electrode is higher than zero potential, with an amplitude range of 1-100V; during the injection period, the bias potentials of the outlet electrode, front cover electrode and radio frequency electrode are lower than zero potential, forming an axial potential gradient in sequence, with an amplitude range of 0-100V, and the potential of the rear cover electrode is higher than zero potential, with an amplitude range of 0-100V; during the capture period, the high trapping potentials of the front cover and rear cover electrodes are higher than zero potential, with an amplitude range of 1-200V; During the cooling period, the low trapped potentials of the front and rear cap electrodes are higher than the zero potential, with an amplitude ranging from 1 to 100 V.

8. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The grid is attached closely to the outlet electrode and is used to shield the electric field of the front cover electrode.

9. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: External ion sources include various types of ion sources at normal pressure and negative pressure.

10. The method for broadening the injection mass range of a linear ion trap / time-of-flight mass spectrometer according to claim 1, characterized in that: The ion extraction method of the linear ion trap is axial extraction.

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