Multifunctional mass spectrometry device and method

Abstract

The application belongs to the field of mass spectrometry, and particularly relates to a multifunctional mass spectrometer and method. The ion trap of the mass spectrometer comprises: a first group of electrodes and a second group of electrodes arranged left and right, each electrode of the first group of electrodes and the second group of electrodes having a through hole allowing ions to pass; a third group of electrodes comprising a plurality of electrodes arranged left and right arranged on the upper side and the lower side of the first group of electrodes and the second group of electrodes respectively; a fourth group of electrodes comprising a plurality of electrodes arranged on the front side and the rear side of the first group of electrodes and the second group of electrodes respectively, the plurality of electrodes each having a slit extending along the left-right direction allowing ions to pass; a radio frequency power supply for providing radio frequency voltage to the third group of electrodes and the fourth group of electrodes; a direct current power supply for providing direct current voltage to the first group of electrodes and the second group of electrodes; and a controller for adjusting the output voltage of the radio frequency power supply and the direct current power supply. The application has the advantages of small size, multiple functions and the like, and can be applied in mass spectrometry.

Description

TECHNICAL FIELD

[0001] The present application relates to mass spectrometry, in particular to a multifunctional mass spectrometer and method. BACKGROUND

[0002] Mass spectrometer is one of the advanced high-end analytical scientific instruments, representing the future development direction of analytical instruments. In the current many mass spectrometry fields, ion transmission, storage and mass detection are all designed for multiple structures and independent action, which has complex structure, resulting in considerable limitations in installation, maintenance and manufacturing cost and miniaturization of mass spectrometer.

[0003] The linear electrostatic trap mass spectrometer of Benner et al. in patent US5880466 is only used for mass measurement of single high-charge molecular ions generated by electrospray. The independent linear electrostatic trap mass spectrometer has simple structure, but the mass resolution is only several hundred, and even the conventional resolution is only several tens.

[0004] Scott et al. introduced a linear ion trap system combining quadrupole bending ion trap, linear quadrupole ion trap, electrostatic linear ion trap and multiple lens electrodes in the article of Analytical Chemistry 2013, 85, 5226-5232. The mass resolution of the mass spectrometry system is only about 1000, and the ion optical system structure is complex, which has high difficulty in installation and debugging. SUMMARY

[0005] In order to solve the above problems in the prior art, the present application provides a multifunctional mass spectrometer.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A multifunctional mass spectrometer, comprising an ion trap and a cooling gas providing unit; the ion trap comprises:

[0008] A first group of electrodes and a second group of electrodes, each electrode of the left and right arranged first group of electrodes and second group of electrodes has a through hole allowing ions to pass through; the cooling gas providing unit provides cooling gas for the area between the first group of electrodes and the second group of electrodes;

[0009] A third group of electrodes, the third group of electrodes comprises a plurality of left and right arranged electrodes arranged on the upper side and the lower side of the first group of electrodes and the second group of electrodes, respectively;

[0010] A fourth group of electrodes, the fourth group of electrodes comprises a plurality of electrodes arranged on the front side and the rear side of the first group of electrodes and the second group of electrodes, respectively, and the plurality of electrodes respectively have a slit extending along the left and right directions allowing ions to pass through;

[0011] a radio frequency power supply for providing radio frequency voltage to the third and fourth sets of electrodes, and a direct current power supply for providing direct current voltage to the first and second sets of electrodes;

[0012] a controller for adjusting the output voltage of the radio frequency power supply and the direct current power supply.

[0013] The present application also provides a method for operating the above-mentioned multifunctional mass spectrometer.

[0014] The method for operating the multifunctional mass spectrometer comprises the following steps:

[0015] In the ion analysis mode, the radio frequency power supply applies radio frequency voltage to the third and fourth sets of electrodes, and the direct current power supply applies different direct current voltage to the first and second sets of electrodes, ions entering the region between the first and second sets of electrodes collide with the cooling gas to slow down and are confined in the region;

[0016] When the frequency of the alternating current voltage applied to the fourth set of electrodes by the radio frequency power supply is the same as the motion frequency of the ions, the ions in the region are ejected from the slit of the fourth set of electrodes.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] By integrating the functions of ion storage, transmission and mass detection into one device, the device can perform ion transmission, ion trap analysis, Fourier transform mass analysis and mixed analysis, and is a high-integration, complete-performance and miniaturization-potential ion trap and ion mass analysis device.

[0019] Compared with the conventional three-dimensional ion trap device, the present application has a larger ion storage capacity. Compared with a simple linear ion trap, the present application has more diversified ion transmission, storage and detection functions, and compared with the Fourier transform ion cyclotron resonance mass spectrometer, the present application has a smaller device size and more diversified application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0020] The disclosure of the present application will become more apparent with reference to the accompanying drawings. It is easily understood by those skilled in the art that the drawings are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. In the drawings:

[0021] Figure 1 is a structural schematic diagram of the multifunctional mass spectrometer of the present application.

[0022] In the drawings, 11 is the first set of electrodes, 12 is the second set of electrodes, 100 is a through hole, 21 is the third set of electrodes, 31 is the fourth set of electrodes, and 311 is a slit. DETAILED DESCRIPTION

[0023] Figure 1 The following description describes optional embodiments of the present application to teach those skilled in the art how to implement and reproduce the present application. Some routine aspects have been simplified or omitted to teach the underlying principles of the present application. Those skilled in the art should understand that variations or substitutions of the embodiments described below will be within the scope of the present application. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present application. Thus, the present application is not limited to the optional embodiments described below, but only by the claims and their equivalents. EMBODIMENT

[0024] A multifunctional mass spectrometer according to an embodiment of the present application includes an ion trap, such as Figure 1 As shown, the ion trap includes:

[0025] a first group of electrodes 11 and a second group of electrodes 12, each electrode of the first group of electrodes 11 and the second group of electrodes 12 having a through hole 100 allowing ions to pass therethrough, and a cooling gas supply unit supplying cooling gas to a region between the first group of electrodes 11 and the second group of electrodes 12;

[0026] a third group of electrodes 21 including a plurality of electrodes arranged left and right on upper and lower sides of the first group of electrodes 11 and the second group of electrodes 12, respectively;

[0027] a fourth group of electrodes 31 including a plurality of electrodes arranged on front and rear sides of the first group of electrodes 11 and the second group of electrodes 12, respectively, the plurality of electrodes each having a slit 311 extending in a left-right direction, allowing ions to pass therethrough;

[0028] a radio frequency power supply for supplying a radio frequency voltage to the third group of electrodes 21 and the fourth group of electrodes 31, and a direct current power supply for supplying a direct current voltage to the first group of electrodes 11 and the second group of electrodes 12;

[0029] a controller for adjusting output voltages of the radio frequency power supply and the direct current power supply.

[0030] Further, each electrode of the first group of electrodes 11 and the second group of electrodes 12 is connected in series with a resistor, and the resistor provides a voltage division.

[0031] Further, the first group of electrodes 11 and the second group of electrodes 12 are implemented as electrode plates, and the third group of electrodes 21 and the fourth group of electrodes 31 are implemented as electrode sheets.

[0032] Further, the third group of electrodes 21 and the fourth group of electrodes 31 enclose a cylindrical region, the first group of electrodes 11 is arranged at the entrance of the cylindrical region, and the second group of electrodes 12 is arranged at the exit of the cylindrical region.

[0033] In order to confine ions, further, the first group of electrodes 11 and the second group of electrodes 12 are axially symmetric.

[0034] In order to realize the Fourier transform mass analysis mode, further, the multifunctional mass spectrometer further comprises:

[0035] A charge amplifier is arranged for detecting the current signal on the third group of electrodes 21.

[0036] A processing unit is arranged for performing Fourier transform on the current signal to obtain frequency spectrum and mass spectrum data.

[0037] The working method of the multifunctional mass spectrometer of the embodiment is as follows:

[0038] In the ion analysis mode, the radio frequency power supply applies radio frequency voltage to the third group of electrodes 21 and the fourth group of electrodes 31, and the direct current power supply applies different direct current voltages to the first group of electrodes 11 and the second group of electrodes 12, ions entering the region between the first group of electrodes 11 and the second group of electrodes 12 collide with cooling gas to slow down and are confined in the region.

[0039] When the radio frequency power supply applies alternating voltage to the fourth group of electrodes 31 at the same frequency as the motion frequency of the ions, the ions in the region are ejected from the slit 311 of the fourth group of electrodes 31.

[0040] In order to realize the Fourier transform mass analysis mode, further, in the Fourier transform mass analysis mode, the third group of electrodes 21 and the fourth group of electrodes 31 apply radio frequency voltage of 0, and the controller adjusts the output voltage of the direct current power supply, and the direct current power supply applies different direct current voltages to the first group of electrodes 11 and the second group of electrodes 12, and the ions are confined in the region and reciprocate in the left-right direction.

[0041] The charge amplifier detects the mirror current signal on the third group of electrodes 21.

[0042] The processing unit performs Fourier transform on the current signal to obtain frequency spectrum and mass spectrum data.

[0043] In order to realize the hybrid analysis mode, further, the Fourier transform mass analysis mode and the ion analysis mode are sequentially performed.

[0044] In order to confine ions, further, in the ion analysis mode, the direct current voltages applied to the two electrodes that are axially symmetric in the first group of electrodes 11 and the second group of electrodes 12 are the same. Embodiment

[0045] According to the application example of the multifunctional mass spectrometer and method in embodiment 1.

[0046] In this application example, as shown in Figure 1 The first group of electrodes 11 and the second group of electrodes 12 each use 5 vertically arranged electrode pieces, the diameter of the through hole on the electrode piece is 2mm, the center axes of the 10 through holes are collinear, and the spacing of the electrode pieces is 5mm. The spacing of adjacent electrodes of the first group of electrodes 11 and the second group of electrodes 12 is 50mm. The electrode pieces of the first group of electrodes 11 and the electrode pieces of the second group of electrodes 12 are distributed in axial symmetry, and each electrode piece is connected in series with a resistor.

[0047] The third group of electrodes 21 includes two isolated horizontal electrode pieces arranged on the upper side of the first group of electrodes 11 and the second group of electrodes 12 along the left-right direction, and two isolated horizontal electrode pieces arranged on the lower side of the first group of electrodes 11 and the second group of electrodes 12 along the left-right direction.

[0048] The fourth group of electrodes 31 includes one vertical electrode piece arranged on the rear side of the first group of electrodes 11 and the second group of electrodes 12, and one vertical electrode piece arranged on the front side of the first group of electrodes 11 and the second group of electrodes 12. Both electrode pieces of the fourth group of electrodes 31 have a slit extending along the left-right direction.

[0049] The third group of electrodes 21 and the fourth group of electrodes 31 enclose a cylindrical region, the first group of electrodes 11 is arranged at the entrance of the cylindrical region, and the second group of electrodes 12 is arranged at the exit of the cylindrical region.

[0050] The radio frequency power supply is used to provide radio frequency voltage for the third group of electrodes 21 and the fourth group of electrodes 31, and the direct current power supply is used to provide direct current voltage for the first group of electrodes 11 and the second group of electrodes 12.

[0051] The controller is used to adjust the output voltage of the radio frequency power supply and the direct current power supply, so that the ion trap is in different working modes.

[0052] The charge amplifier is used to detect the current signal on the third group of electrodes 21. The processing unit performs Fourier transform on the current signal to obtain frequency spectrum and mass spectrum data.

[0053] The working method of the multifunctional mass spectrometer in this embodiment is as follows:

[0054] 1. Ion focusing confinement mode.

[0055] For positive ions, the five electrode pieces of the first group of electrodes 11 and the second group of electrodes 12, from the ion trap edge to the center, are respectively provided with direct current voltages of 10V, 7V, 2V, -1V, and 1V, forming a potential well structure with a symmetric center low potential. The electric field strength distribution range is 0.4-20V / mm.

[0056] The voltage on the third group of electrodes 21 and the fourth group of electrodes 31 is 0, so that the first group of electrodes 11 and the second group of electrodes 12 are axially symmetric structures, and the voltage applied to the two groups of electrodes makes the ions in the focusing confinement mode of the ion trap.

[0057] After binding a certain amount of ions, such as according to the size of the front ion flow flux, it is determined that after 10ms, the output voltage of the direct current power supply is adjusted by the controller to make the voltage on each electrode piece in the second group of electrodes 12 0V, -1V, -2V, -3V, -6V, and -7V, respectively.

[0058] The ion trap is in the focusing transmission mode, and the ions with corresponding demand momentum dispersion can be controlled, and the optimized ion spatial momentum dispersion angle is less than 0.05 rad. In this potential distribution structure with gradient distribution but non-uniform electric field, the electric field with potential structure first guides the axially injected ions by the gradient field of the first group of electrodes 11. Due to the binding of the electric field, the ions have a focusing confinement effect in the electric field formed by the first group of electrodes 11 and the second group of electrodes 12, and have a smaller beam diameter when passing through the second group of electrodes 12.

[0059] Without applying an external magnetic field and an excitation electric field, the spatial focusing of the injected ion beam is realized by changing the potential of different electrode pieces in the first group of electrodes 11 and the second group of electrodes 12, the position dispersion is reduced, the momentum dispersion of the ion beam is improved, and the energy of the ion beam is regulated to realize the extraction with target kinetic energy.

[0060] 2. Ion trap mass analysis mode.

[0061] For positive ions, the five electrode pieces of the first group of electrodes 11 and the second group of electrodes 12, from the ion trap edge to the center, are respectively provided with direct current voltages of 10V, 7V, 2V, -1V, and 1V, forming a potential well structure with a symmetric center low potential. The electric field strength distribution range is 0.4-20V / mm.

[0062] The RF electric field is applied to the electrode sheets of the third group of electrodes 21 and the fourth group of electrodes 31 simultaneously to confine the injected ions, and a collisional bath gas is supplied by the collisional cooling gas supply assembly to provide a collisional bath gas in the trap region, the pressure of the bath gas being preferably 0.5 mtorr, so that the ions are decelerated to the lowest point of the potential well and confined in the center of the trap region, to achieve ion storage and compression. After the injection time of 3-15 ms, the ion beam is decelerated and focused in the region between the first group of electrodes 11 and the second group of electrodes 12 by increasing the voltage on the first group of electrodes 11, and the electric field of the second group of electrodes 12 is reversed to decelerate and optimize the position dispersion of the ion beam after focusing in the trap region. The voltage between the first group of electrodes 11 and the second group of electrodes 12 is gradually increased to make the depth of the potential well reach 200 eV for singly-charged ions, and the ion beam density in the storage region is increased.

[0063] The resonant AC voltage provided by the RF power supply is applied to the fourth group of electrodes 31 to simulate the frequency of ion motion in the direction of the ion detection system (transversely). When the AC frequency applied to the fourth group of electrodes 31 is the same as the motion frequency of the trapped ions (depending on their mass number), the ions gain kinetic energy. If the applied voltage is high enough or the ions are given enough time, the ions will be ejected from the slit 311. The ion beam is ejected transversely through the slit 311 to an ion beam detection device outside the electrode sheets, such as a continuous channel electron multiplier, to detect the beam current intensity of the ion beam of a specific mass number.

[0064] 3. Fourier transform mass analysis mode.

[0065] The RF electric field is not applied to the third group of electrodes 21 and the fourth group of electrodes 31 to confine the injected ions, and the controller regulates the DC voltage applied to the electrode sheets of the first group of electrodes 11 and the second group of electrodes 12 by the DC power supply to confine the ions in the axial region of the first group of electrodes 11 and the second group of electrodes 12 to make axial reciprocating motion.

[0066] The image current signal generated on the third group of electrodes 21 during the cyclotron motion of the ions is collected by the low-noise charge-sensitive amplifier connected to the third group of electrodes 21.

[0067] The data processing system performs Fourier transform and other data processing to convert the frequency spectrum and mass spectrum data.

[0068] The single mass detection resolution can reach 100,000 orders of magnitude using this working mode for non-destructive detection.

[0069] 4. Mixed analysis mode.

[0070] First, the ion trap mass analysis mode is performed to analyze ions of different masses, determine the relative number of ions of a target mass number injected into the ion trap per unit time, and then control the ion injection time by changing the interval time of the voltage pulses of the first group of electrodes 11 and the second group of electrodes 12, so as to constrain the ion beam current within the expected ion injection time.

[0071] Then, the ions are subjected to Fourier transform mass analysis to detect the controllable number of ion beams.

Claims

1. A multi-functional mass spectrometer comprising an ion trap and a cooling gas supply unit; characterized by, The ion trap comprises: a first group of electrodes and a second group of electrodes, each electrode of the first group of electrodes and the second group of electrodes having a through hole allowing ions to pass through; the cooling gas supply unit supplies cooling gas to the region between the first group of electrodes and the second group of electrodes; the first group of electrodes and the second group of electrodes each comprise five electrode plates, and the first group of electrodes and the second group of electrodes are axially symmetrical; a third group of electrodes, the third group of electrodes comprising a plurality of electrodes arranged left and right on the upper side and the lower side of the first group of electrodes and the second group of electrodes respectively; a fourth group of electrodes, the fourth group of electrodes comprising a plurality of electrodes arranged on the front side and the rear side of the first group of electrodes and the second group of electrodes respectively, the plurality of electrodes each having a slit extending along the left-right direction and allowing ions to pass through; a radio frequency power supply and a direct current power supply, the radio frequency power supply being configured to supply a radio frequency voltage to the third group of electrodes and the fourth group of electrodes, and the direct current power supply being configured to supply a direct current voltage to the first group of electrodes and the second group of electrodes; a controller configured to adjust the output voltage of the radio frequency power supply and the direct current power supply; the third group of electrodes and the fourth group of electrodes enclose a cylindrical region, the first group of electrodes is arranged at the entrance of the cylindrical region, and the second group of electrodes is arranged at the exit of the cylindrical region.

2. The multi-functional mass spectrometer of claim 1, wherein, Each electrode of the first group of electrodes and the second group of electrodes is connected in series with a resistor.

3. The multi-functional mass spectrometer of claim 1, wherein, The first group of electrodes and the second group of electrodes are electrode plates, and the third group of electrodes and the fourth group of electrodes are electrode plates.

4. The multi-functional mass spectrometer of claim 1, wherein The multi-functional mass spectrometer further comprises: a charge amplifier configured to detect a current signal on the third group of electrodes; a processing unit configured to perform Fourier transform on the current signal to obtain frequency spectrum and mass spectrum data.

5. A method for operating the multi-functional mass spectrometer according to claim 1, the method comprising: in an ion trap mass analysis mode, the radio frequency power supply applies a radio frequency voltage to the third group of electrodes and the fourth group of electrodes, the direct current power supply applies different direct current voltages to the first group of electrodes and the second group of electrodes, ions entering the region between the first group of electrodes and the second group of electrodes collide with the cooling gas to slow down, and are confined in the region between the first group of electrodes and the second group of electrodes; when the radio frequency power supply applies an alternating current voltage to the fourth group of electrodes at a frequency equal to the motion frequency of the ions, the ions in the region between the first group of electrodes and the second group of electrodes are ejected from the slit of the fourth group of electrodes.

6. The method of working according to claim 5, characterized in that, in a Fourier transform mass analysis mode, the third group of electrodes and the fourth group of electrodes do not apply a radio frequency voltage, the controller adjusts the output voltage of the direct current power supply, the direct current power supply applies different direct current voltages to the first group of electrodes and the second group of electrodes, and the ions are confined in the region between the first group of electrodes and the second group of electrodes and perform reciprocating motion in the left-right direction; the charge amplifier detects a mirror current signal on the third group of electrodes; the processing unit performs Fourier transform on the current signal to obtain frequency spectrum and mass spectrum data.

7. The method of working according to claim 6, characterized in that, the ion trap mass analysis mode and the Fourier transform mass analysis mode are performed sequentially.

8. The method of claim 5, wherein, in the ion analysis mode, the direct current voltages applied to the two electrodes of the first group of electrodes and the second group of electrodes that are axially symmetrical are the same.

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