Electrostatic lens and ion trap composite structure EI source quadrupole mass spectrometer and control method

Abstract

The invention discloses an EI source quadrupole mass spectrometer of an electrostatic lens and ion trap composite structure and a control method, and relates to the technical field of ion transmission, the EI source quadrupole mass spectrometer comprises an EI ion source, the electrostatic lens and ion trap composite structure, a quadrupole mass analyzer and a detector which are arranged in sequence, the EI ion source is used for generating and extracting ions, and the quadrupole mass analyzer is used for detecting the EI ion source. The electrostatic lens and ion trap composite structure comprises an electrostatic lens assembly and a miniature ion trap, and the electrostatic lens assembly is used for dynamically adjusting voltage according to the molecular weight of ions, forming a gradient electric field, achieving accurate collimation and focusing of ion beams and improving the ion transmission efficiency. The micro ion trap is used for temporarily storing and enriching ions and increasing the number of ions entering the quadrupole rod mass analyzer, the quadrupole rod mass analyzer is used for carrying out mass scanning and screening on the ions, and the detector is used for detecting the screened ions, so that the detection precision of a low-concentration trace organic matter sample is improved.

Description

Technical Field

[0001] This invention relates to the field of ion transport technology, specifically to an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap, and its control method. Background Technology

[0002] Electron impact ionization (EI) source single quadrupole mass spectrometers are widely used in environmental monitoring, food safety, and pharmaceutical analysis due to their relatively simple structure, low cost, and good qualitative capabilities. During operation, sample ions generated by the EI source need to pass through a transmission system into the quadrupole mass analyzer for mass screening before being detected by the detector. Therefore, the ion transmission efficiency directly affects the instrument's detection sensitivity and signal-to-noise ratio.

[0003] In traditional EI-source single quadrupole mass spectrometers, the ion transport system employs a simple multi-stage electrostatic lens structure. This structure has the following drawbacks: Firstly, the ion beam generated by the EI source has a certain degree of divergence, making it difficult for the electrostatic lens to achieve precise collimation and focusing of ions with different molecular weights. This results in the loss of some ions during transport, reducing ion transport efficiency. Secondly, for low-concentration trace organic samples (where the organic content is extremely low), the number of ion fragments generated by the EI source is limited. Traditional transport systems cannot effectively enrich ions, further reducing the number of ions entering the quadrupole mass analyzer. This leads to a weaker signal detected by the detector, a low signal-to-noise ratio, and makes it difficult to meet the high-precision detection requirements for trace organic compounds. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the detection accuracy of EI source single quadrupole mass spectrometers for low concentrations of trace organic matter is low in the prior art. The purpose is to provide an EI source quadrupole mass spectrometer with a composite structure of electrostatic lens and ion trap and a control method, thereby solving the above-mentioned problem.

[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap, the EI source quadrupole mass spectrometer comprising, in sequence, an EI ion source, a composite structure of an electrostatic lens and an ion trap, a quadrupole mass analyzer and a detector; the EI source quadrupole mass spectrometer further includes a timing control system; the composite structure of the electrostatic lens and the ion trap includes an electrostatic lens assembly and a miniature ion trap. The EI ion source is used to generate and extract ions under the control of the timing control system. The electrostatic lens assembly includes at least three sets of ring electrodes, each set of ring electrodes being connected to an independent voltage adjustment module; the voltage adjustment module is used to dynamically adjust the voltage of the connected ring electrodes according to the molecular weight of the ions under the control of the timing control system, thereby forming a gradient electric field. The micro ion trap is used to store and enrich received ions under the control of the timing control system, and to send the enriched ions into the quadrupole mass analyzer in a pulsed manner. The quadrupole mass analyzer is used to perform mass scanning and screening of pulsed ions under the control of the timing control system. The detector is used to detect the screened ions under the control of the timing control system.

[0006] Optionally, the micro ion trap includes a cylindrical trap body, the trap body includes an ion inlet end and an ion outlet end, both of which are provided with a gate; at least two sets of radio frequency electrodes are symmetrically arranged on the inner wall of the trap body, and each set of radio frequency electrodes is connected to a radio frequency power supply. The radio frequency power supply is used to output radio frequency voltage under the control of the timing control system to form an electric field for trapped ions in the trap. The gate is used to be turned on and off under the control of the timing control system.

[0007] Optionally, the trap body is made of 316L stainless steel, and the inner wall of the trap body is uniformly plated with gold with a gold layer thickness of 5μm.

[0008] Optionally, the EI ion source includes an ionization chamber, a filament, and an ion extraction electrode, wherein the ion extraction electrode is electrically connected to the timing control system. The ion extraction electrode is used to output ions generated by the filament under the control of the timing control system, so that the ions generated by the EI ion source are synchronized with the ions received by the micro ion trap in time.

[0009] Optionally, the electrostatic lens assembly includes three sets of ring electrodes, with an insulating pad between adjacent sets of ring electrodes; the three sets of ring electrodes include a first ring electrode near the EI ion source, a third ring electrode near the micro ion trap, and a second ring electrode located between the first ring electrode and the third ring electrode; the voltage regulation module includes a first voltage module connected to the first ring electrode, a second voltage module connected to the second ring electrode, and a third voltage module connected to the third ring electrode; The first voltage regulation module is specifically used to: adjust the voltage of the first ring electrode to a first voltage under the control of the timing control system; The second voltage regulation module is specifically used to: under the control of the timing control system, regulate the voltage of the second ring electrode to a second voltage; the first voltage is greater than the second voltage; The third voltage adjustment module is specifically used to: adjust the voltage of the third ring electrode to a third voltage under the control of the timing control system; the third voltage is greater than the second voltage.

[0010] Optionally, the quadrupole quality analyzer includes four parallel poles connected to a radio frequency (RF) and DC composite power supply; the RF and DC composite power supply is used to provide power to the poles.

[0011] Optionally, the detector employs an electron multiplier, which is electrically connected to the timing control system; the electron multiplier is used to increase the gain of pulsed ions under the control of the timing control system.

[0012] Secondly, the present invention provides a control method for an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap, applied in the timing control system included in the EI source quadrupole mass spectrometer described in any one of the first aspects; the method includes: Control the EI ion source to generate and extract ions; The voltage regulation module dynamically adjusts the voltage of the connected ring electrode according to the molecular weight of the ions to form a gradient electric field; The micro ion trap is controlled to store and enrich the received ions, and the enriched ions are sent into the quadrupole mass analyzer in a pulsed manner. The quadrupole mass analyzer is controlled to perform mass scanning and screening of pulsed ions. The detector is controlled to detect the screened ions.

[0013] Optionally, controlling the micro ion trap to store and enrich the received ions, and then pulse-feeding the enriched ions into the quadrupole mass analyzer, includes: The gate at the ion inlet is turned on at the first moment; The gate at the ion inlet is controlled to close at a second time, while the radio frequency power supply is controlled to output radio frequency voltage to store and enrich the received ions in the micro ion trap; the first time is earlier than the second time. The gate at the ion outlet is controlled to be turned on during a third time period, and the enriched ions are pulsed into the quadrupole mass analyzer; the second time period is earlier than the third time period.

[0014] Optionally, controlling the quadrupole mass analyzer to perform mass scanning and screening of pulsed ions includes: The quadrupole mass analyzer is controlled to perform mass scanning and screening of pulsed ions at a fourth time; the third time is earlier than the fourth time. The control of the detector to detect the screened ions includes: Increase the gain of the screened ions and then detect the ions with increased gain.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: This application employs a composite structure of an electrostatic lens and an ion trap between the EI source and the quadrupole mass analyzer. The electrostatic lens component in this composite structure dynamically adjusts the voltage according to the molecular weight of the ions, creating a gradient electric field to achieve precise collimation and focusing of the ion beam. This reduces ion divergence losses during transmission and improves ion transmission efficiency. Furthermore, the miniature ion trap within the composite structure can temporarily store and enrich ions, significantly increasing the number of ions entering the quadrupole mass analyzer. This, in turn, improves the signal-to-noise ratio and detection accuracy of low-concentration trace organic samples. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 A schematic diagram of an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap provided in this application embodiment; Figure 2 This is a schematic diagram of the structure of an EI ion source provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of an electrostatic lens assembly provided in an embodiment of this application; Figure 4 A schematic diagram of a micro ion trap provided in this application embodiment. Figure 5 This is a flowchart illustrating a control method for an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap, as provided in an embodiment of this application.

[0017] Figure label: 1-EI ion source; 2-Combined structure of electrostatic lens and ion trap; 3-Quadrupole mass analyzer; 4-Detector; 5-Timing control system; 11-Ionization chamber; 12-Filament; 13-Ion extraction electrode; 21-Electrostatic lens assembly; 22-Miniature ion trap; 210-Insulating pad; 211-First ring electrode; 212-Second ring electrode; 213-Third ring electrode; 214-First voltage regulation module; 215-Second voltage regulation module; 216-Third voltage regulation module; 221-Trap body; 222-Ion inlet end; 223-Ion outlet end; 224-RF electrode; RF power supply 225. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are only for explaining this invention and are not intended to limit this invention.

[0019] Please refer to Figure 1 This is a schematic diagram of an EI source quadrupole mass spectrometer with an electrostatic lens and ion trap composite structure provided in an embodiment of this application. The EI source quadrupole mass spectrometer includes an EI ion source 1, an electrostatic lens and ion trap composite structure 2, a quadrupole mass analyzer 3, and a detector 4 arranged sequentially. The EI ion source 1, the electrostatic lens and ion trap composite structure 2, the quadrupole mass analyzer 3, and the detector 4 are all electrically connected to a timing control system 5.

[0020] EI ion source 1 is used to generate and extract ions under the control of timing control system 5.

[0021] The electrostatic lens and ion trap composite structure 2 includes an electrostatic lens assembly 21 and a micro ion trap 22; the electrostatic lens assembly 21 includes at least three sets of ring electrodes, each set of ring electrodes being connected to an independent voltage regulation module.

[0022] The voltage regulation module is used to dynamically adjust the voltage of the connected ring electrode according to the molecular weight of the ions under the control of the timing control system 5, thereby forming a gradient electric field. The miniature ion trap 202 is used to store and enrich the received ions under the control of the timing control system 5, and then send the enriched ions into the quadrupole mass analyzer 3 in a pulsed manner.

[0023] The quadrupole mass analyzer 3 is used to perform mass scanning and screening of pulsed ions under the control of the timing control system 5.

[0024] Detector 4 is used to detect the screened ions under the control of timing control system 5.

[0025] In practical implementation, the EI ion source 1 is a device that generates ions by bombarding gaseous sample molecules with a high-speed electron beam, causing them to lose electrons or break bonds. The quadrupole mass analyzer 3 is a device that uses a radio frequency electric field for mass filtering. Only ions that meet specific stable motion conditions can pass through the quadrupole to reach the detector 4; other ions are annihilated by collisions with the quadrupole due to excessive amplitude, thus achieving ion mass screening. The detector 4 converts the ion signal (ion flow) into an electrical signal (current) and amplifies the signal for measurement and recording.

[0026] In this embodiment, an electrostatic lens and ion trap composite structure 2 is provided between the EI ion source 1 and the quadrupole mass analyzer 3. The voltage adjustment module of the electrostatic lens assembly 21 can dynamically adjust the voltage according to the molecular weight of the ions to form a gradient electric field, thereby achieving precise focusing of the ion beam, reducing ion divergence loss during transmission, and improving ion transmission efficiency. The miniature ion trap 22 can temporarily store and enrich ions, significantly increasing the number of ions entering the quadrupole mass analyzer 3, thus improving the signal-to-noise ratio of low-concentration trace organic samples. Simulation results show that, compared to a traditional EI source single quadrupole mass spectrometer, the EI source quadrupole mass spectrometer provided in this application can improve the signal-to-noise ratio of low-concentration trace organic samples by approximately 5 times.

[0027] In one possible embodiment, please refer to Figure 2 This is a structural diagram of an EI ion source provided by the present invention. The EI ion source 1 includes an ionization chamber 11, a filament 12, and an ion extraction electrode 13. The ion extraction electrode 13 is electrically connected to a timing control system 5. The ion extraction electrode 13 is used to output ions generated by the filament under the control of the timing control system 5, so that the ions generated by the EI ion source 1 are synchronized with the ions received by the micro ion trap 22 in time.

[0028] In the specific implementation process, the filament 12 is located inside the ionization chamber 11 and is used to emit an electron beam to cause electron bombardment ionization (EI) of the vaporized sample molecules, generating ions. The ion extraction electrode 13 is located at the outlet of the ionization chamber 11 and is used to extract ions to the subsequent electrostatic lens assembly 21 under the action of an electric field. The timing control system 5 can precisely control the voltage of the ion extraction electrode 13, so that the ions generated by the EI ion source 1 and the ions received by the micro ion trap 22 are synchronized in time.

[0029] In this embodiment, timing synchronization control ensures that ions are introduced only when the micro ion trap 22 is ready to receive, avoiding interference from continuous ion flow to ions already stored in the trap, and ensuring that the micro ion trap 22 can effectively enrich specific ions during the quiet period, thereby improving enrichment efficiency and signal-to-noise ratio.

[0030] In one possible embodiment, please refer to Figure 3 This is a schematic diagram of the electrostatic lens assembly provided in an embodiment of this application. The electrostatic lens assembly 21 includes three sets of ring electrodes, with an insulating pad 210 between adjacent sets of ring electrodes. The three sets of ring electrodes include a first ring electrode 211 near the EI ion source 1, a third ring electrode 213 near the micro ion trap, and a second ring electrode 212 located between the first ring electrode 211 and the third ring electrode 213. The voltage regulation module includes a first voltage module 214 connected to the first ring electrode 211, a second voltage module 215 connected to the second ring electrode 212, and a third voltage module 216 connected to the third ring electrode 213.

[0031] The first voltage regulation module 214 is specifically used to: adjust the voltage of the first ring electrode 211 to a first voltage under the control of the timing control system 5; the second voltage regulation module 215 is specifically used to: adjust the voltage of the second ring electrode 212 to a second voltage under the control of the timing control system; the first voltage is greater than the second voltage; the third voltage regulation module 216 is specifically used to: adjust the voltage of the third ring electrode 213 to a third voltage under the control of the timing control system; the third voltage is greater than the second voltage.

[0032] In specific implementation, the insulating pad 210 can be made of ceramic. The first voltage adjustment module 214 can adjust the voltage of the first annular electrode 211 to -200 ~ -50V, the second voltage adjustment module 215 can adjust the voltage of the second annular electrode 212 to -300V ~ -100V, and the third voltage adjustment module 216 can adjust the voltage of the third annular electrode 213 to -200V ~ -50V, so as to form a gradient electric field with a high middle and low ends in the ion transport path, which can adapt to the focusing requirements of ions with different molecular weights.

[0033] For example, when detecting organic ions with a molecular weight of 100 to 300 Da, the voltage of the first ring electrode 211 is adjusted to -100 V, the voltage of the second ring electrode 212 is adjusted to -200 V, and the voltage of the third ring electrode 213 is adjusted to -100 V, forming a gradient electric field that is high in the middle and low at both ends.

[0034] In this embodiment, the electrostatic lens assembly 21 uses three sets of independently voltage-adjustable ring electrodes. While ensuring the simple structure of the electrostatic lens assembly 21, it achieves flexible and adjustable electric field distribution, which can adapt to the focusing requirements of ions with different molecular weights, and improves the applicability and analytical performance of the EI source single quadrupole mass spectrometer.

[0035] In one possible embodiment, please refer to Figure 4This is a schematic diagram of a micro ion trap provided in an embodiment of this application. The micro ion trap 22 includes a cylindrical trap body 221, which includes an ion inlet end 222 and an ion outlet end 223. Both the ion inlet end 222 and the ion outlet end 223 are provided with a gate. At least two sets of radio frequency electrodes 224 are symmetrically arranged on the inner wall of the trap body 221, and each set of radio frequency electrodes 224 is connected to a radio frequency power supply 225. The radio frequency power supply 225 is used to output radio frequency voltage under the control of the timing control system 5 to form an electric field for trapping ions in the trap body 221. The gate is used to be turned on and off under the control of the timing control system 5.

[0036] In the specific implementation process, at least two sets of radio frequency electrodes 224 are symmetrically arranged on the inner wall of the trap 221. Each set of radio frequency electrodes 224 is connected to a radio frequency power supply 225, which can output a radio frequency voltage with a frequency of 1~5MHz and an amplitude of -1500~-500V to form an electric field for trapping ions within the trap 221. The gates of the ion inlet end 222 and the ion outlet end 223 are both made of a mesh structure woven from molybdenum wire, with a mesh aperture of 0.1~0.5mm. The gate's on-state voltage is -50~-10V, and the gate's off-state voltage is 0~50V. The timing control system 5 precisely controls the on and off states of the gates to achieve the orderly storage, enrichment, and release of ions.

[0037] In one possible embodiment, the radio frequency power supply is used to output a radio frequency voltage with a frequency of 3MHz and an amplitude of 1000V under the control of the timing control system 5; the grid aperture of the gates of the ion inlet end 222 and the ion outlet end 223 is 0.3mm, the gate on voltage is 30V, and the gate off voltage is -20V.

[0038] In one possible embodiment, the trap body 221 is made of 316L stainless steel, and the inner wall of the trap body 221 is uniformly plated with gold with a gold layer thickness of 5μm.

[0039] In this embodiment, the micro ion trap 22 is made of stainless steel and has a 5μm gold plating layer, which can reduce the collision loss of ions with the inner wall of the trap 221 during storage, thereby improving the storage efficiency and enrichment effect of the micro ion trap 22.

[0040] In one possible embodiment, the quadrupole mass analyzer 3 includes four parallel poles connected to a radio frequency (RF) and DC composite power supply; the RF and DC composite power supply is used to provide power to the poles.

[0041] In this embodiment, the timing control system 5 is communicatively connected to the radio frequency and DC composite power supply of the quadrupole mass analyzer 3, and can control the output parameters of the radio frequency and DC composite power supply (radio frequency voltage amplitude, DC voltage amplitude, and scan rate, etc.). When the micro ion trap 22 releases the enriched ions to the quadrupole mass analyzer 3 in the form of pulses, it synchronously triggers the radio frequency and DC composite power supply to start the voltage scan of the preset program, so that the quadrupole mass analyzer 3 performs selective ion filtering within the corresponding mass number range (e.g., 100 ~ 300 Da), thereby realizing the synchronous reception and screening of target ions.

[0042] In one possible embodiment, detector 4 employs an electron multiplier electrically connected to timing control system 5; the electron multiplier is used to increase the gain of pulsed ions under the control of timing control system 5.

[0043] In this embodiment, detector 4 employs an electron multiplier, and its gain is synchronized with the ion pulse release via a timing control system 5. When the micro ion trap 22 releases pulsed ions, the gain of detector 4 increases synchronously, specifically enhancing the signal intensity of low-abundance ions while avoiding saturation of high-abundance ion signals. This effectively expands the detection dynamic range and further improves the sensitivity and accuracy of trace organic matter detection.

[0044] In summary, this application provides an EI-source quadrupole mass spectrometer that breaks through the traditional transmission mode of a single electrostatic lens or ion guide. It innovatively integrates an electrostatic lens assembly 21 and a miniature ion trap 22 between the EI ion source 1 and the quadrupole mass analyzer 3, forming a dual-function composite transmission system of "focusing + enrichment". The electrostatic lens assembly 21 forms a gradient electric field through three sets of independently voltage-adjustable ring electrodes, achieving precise focusing of ions of different molecular weights. The miniature ion trap 22 traps ions through a radio frequency electric field, solving the problem that traditional transmission systems cannot effectively enrich low-concentration ions. The two work synergistically to improve ion transmission efficiency and enrichment effect, thereby enhancing the signal-to-noise ratio for detecting low-concentration trace organic samples.

[0045] Based on the same inventive concept, this application also provides a control method for an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap, which is applied to the timing control system 5 included in the aforementioned EI source quadrupole mass spectrometer. Please refer to... Figure 5 This is a flowchart illustrating a control method for an EI source quadrupole mass spectrometer with a composite structure of an electrostatic lens and an ion trap, as provided in this application. The method includes: S501, controls the generation and extraction of ions from the EI ion source; S502, The control voltage adjustment module dynamically adjusts the voltage of the connected ring electrode according to the molecular weight of the ions to form a gradient electric field; S503: Control the micro ion trap to store and enrich the received ions, and send the enriched ions into the quadrupole mass analyzer in a pulsed manner. S504 controls the quadrupole mass analyzer to perform mass scanning and screening of pulsed ions; S505, control the detector to detect the screened ions.

[0046] In one possible embodiment, step S503 includes: The gate at the ion inlet is turned on at the first time; the gate at the ion inlet is turned off at the second time, and the radio frequency power supply is controlled to output radio frequency voltage to store and enrich the received ions in the miniature ion trap; the first time is earlier than the second time; the gate at the ion outlet is turned on at the third time to send the enriched ions into the quadrupole mass analyzer in a pulsed manner; the second time is earlier than the third time.

[0047] In one possible embodiment, step S504 includes: controlling the quadrupole mass analyzer to perform mass scanning and screening of pulsed ions at a fourth time; the third time is earlier than the fourth time; The steps in S505 include: increasing the gain of the screened ions and detecting the ions with increased gain.

[0048] In the specific implementation process, the timing control system 5 controls the gate of the ion inlet 222 to be turned on within 0~5ms to receive ions focused by the electrostatic lens assembly 21, and turns off the gate of the ion inlet 222 within 5~30ms. At the same time, it controls the RF power supply 225 to output RF voltage, so that ions are stored and enriched in the micro ion trap 22. The timing control system 5 controls the gate of the ion outlet 223 to be turned on within 30~32ms, and sends the enriched ions into the quadrupole mass analyzer 3 in a pulsed manner. At the same time, it controls the ion extraction electrode 13 to stop extracting ions. The quadrupole mass analyzer 3 performs a simultaneous scan of the mass range of 100~300Da within 32~52ms to screen target ions. The detector 4 increases the gain to 3 times the normal state within 32~52ms to enhance the detection signal strength.

[0049] In summary, the control method for an EI-source quadrupole mass spectrometer provided in this application achieves full-process coordination of the EI ion source 1, electrostatic lens assembly 21, miniature ion trap 22, quadrupole mass analyzer 3, and detector 4 through a timing control system 5. By precisely controlling the on / off timing of the gates at the ion inlet and outlet ends (e.g., 0-5ms for ion reception, 5-30ms for enrichment, and 30-32ms for release), the voltage of the ion extraction electrode 13, the scanning parameters of the quadrupole mass analyzer 3, and the gain of the detector 4 are synchronously adjusted, enabling ion transport, enrichment, screening, and detection to form a pulsed linkage. This avoids interference from invalid ions and improves the detection efficiency and signal-to-noise ratio for low-concentration trace organic samples.

[0050] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0051] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0052] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An EI source quadrupole mass spectrometer of electrostatic lens and ion trap complex structure, characterized in that, The EI source quadrupole mass spectrometer comprises an EI ion source, an electrostatic lens and ion trap composite structure, a quadrupole mass analyzer and a detector arranged in sequence; the EI source quadrupole mass spectrometer further comprises a timing control system; the electrostatic lens and ion trap composite structure comprises an electrostatic lens assembly and a micro ion trap; The EI ion source is used to generate and lead out ions under the control of the timing control system; The electrostatic lens assembly comprises at least three groups of ring electrodes, and each group of ring electrodes is connected with an independent voltage adjusting module; the voltage adjusting module is used to dynamically adjust the voltage of the connected ring electrode according to the molecular weight of the ions under the control of the timing control system, so as to form a gradient electric field; The micro ion trap is used to store and enrich the received ions under the control of the timing control system, and to send the enriched ions into the quadrupole mass analyzer in a pulse mode; The quadrupole mass analyzer is used to perform mass scanning and screening on the ions in a pulse mode under the control of the timing control system; The detector is used to detect the screened ions under the control of the timing control system.

2. The EI source quadrupole mass spectrometer of a combined electrostatic lens and ion trap structure as claimed in claim 1, wherein, The micro ion trap comprises a cylindrical trap body, the trap body comprises an ion inlet end and an ion outlet end, and the ion inlet end and the ion outlet end are both provided with a grid; at least two groups of radio frequency electrodes are symmetrically arranged on the inner wall of the trap body, and each group of radio frequency electrodes is connected with a radio frequency power supply; The radio frequency power supply is used to output a radio frequency voltage under the control of the timing control system, so as to form an electric field for trapping ions in the trap body; The grid is used to be turned on and turned off under the control of the timing control system.

3. The EI source quadrupole mass spectrometer of a composite structure of electrostatic lens and ion trap according to claim 2, characterized in that, The material of the trap body is 316L stainless steel, and the inner wall of the trap body is uniformly plated with gold, and the thickness of the gold layer is 5 μm.

4. The EI source quadrupole mass spectrometer of a composite structure of electrostatic lens and ion trap according to claim 1, characterized in that, The EI ion source comprises an ionization chamber, a filament and an ion leading-out electrode, the ion leading-out electrode is electrically connected with the timing control system; The ion leading-out electrode is used to output the ions generated by the filament under the control of the timing control system, so that the ions generated by the EI ion source are kept synchronous with the ions received by the micro ion trap in time sequence.

5. The EI source quadrupole mass spectrometer of a composite structure of electrostatic lens and ion trap according to claim 1, characterized in that, The electrostatic lens assembly comprises three groups of ring electrodes, and an insulating gasket is arranged between two adjacent groups of ring electrodes; the three groups of ring electrodes comprise a first ring electrode close to the EI ion source, a third ring electrode close to the micro ion trap, and a second ring electrode between the first ring electrode and the third ring electrode; the voltage adjusting module comprises a first voltage module connected with the first ring electrode, a second voltage module connected with the second ring electrode, and a third voltage module connected with the third ring electrode; The first voltage adjusting module is specifically used to adjust the voltage of the first ring electrode to a first voltage under the control of the timing control system; The second voltage adjusting module is specifically used to adjust the voltage of the second ring electrode to a second voltage under the control of the timing control system; the first voltage is greater than the second voltage; The third voltage adjusting module is specifically configured to adjust the voltage of the third ring electrode to a third voltage under the control of the timing control system; the third voltage is greater than the second voltage.

6. The EI source quadrupole mass spectrometer of a composite structure of electrostatic lens and ion trap according to claim 1, characterized in that, The quadrupole rod mass analyzer comprises four parallel rods, and the rods are connected with a radio frequency and direct current composite power supply; the radio frequency and direct current composite power supply is used to provide power for the rods.

7. The EI source quadrupole mass spectrometer of a composite structure of electrostatic lens and ion trap according to claim 1, characterized in that, The detector adopts an electron multiplier, and the electron multiplier is electrically connected with the timing control system; the electron multiplier is used to increase the gain of the pulsed ions under the control of the timing control system.

8. A control method of an EI source quadrupole mass spectrometer with an electrostatic lens and ion trap composite structure, applied to a timing control system included in the EI source quadrupole mass spectrometer of any one of claims 1-7; the method comprises: controlling the EI ion source to generate and emit ions; controlling the voltage adjusting module to dynamically adjust the voltage of the connected ring electrode according to the molecular weight of the ions to form a gradient electric field; controlling the micro ion trap to store and enrich the received ions, and to send the enriched ions in a pulsed manner into the quadrupole rod mass analyzer; controlling the quadrupole rod mass analyzer to perform mass scanning and screening on the pulsed ions; controlling the detector to detect the screened ions.

9. The method of claim 8, wherein the method further comprises: applying a voltage to the ion guide to cause the ions to exit the ion guide and enter the ion trap. The control of the micro ion trap to store and enrich the received ions, and to send the enriched ions in a pulsed manner into the quadrupole rod mass analyzer comprises: ​ controlling the gate at the ion inlet end to be turned on at a first time; controlling the gate at the ion inlet end to be turned off at a second time, while controlling the radio frequency power supply to output a radio frequency voltage, so as to store and enrich the received ions in the micro ion trap; the first time is earlier than the second time; controlling the gate at the ion outlet end to be turned on at a third time, so as to send the enriched ions in a pulsed manner into the quadrupole rod mass analyzer; the second time is earlier than the third time.

10. The method of claim 9, wherein the method further comprises: The control of the quadrupole rod mass analyzer to perform mass scanning and screening on the pulsed ions comprises: controlling the quadrupole rod mass analyzer to perform mass scanning and screening on the pulsed ions at a fourth time; the third time is earlier than the fourth time. The control of the detector to detect the screened ions comprises: increasing the gain of the screened ions, and detecting the ions with increased gain.

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