Ion deflection system of multifunctional inductively coupled plasma mass spectrometer

Abstract

The invention discloses an arc cylindrical surface ion deflection system for inductively coupled plasma mass spectrometry. The arc cylindrical surface ion deflection system comprises a core deflection lens group, an ion focusing lens group and an assembly part, the ion deflection system can enable the flight direction of ions to deflect at a certain angle; moreover, by adjusting the direct-current voltage applied to the core deflection lens group and the ion focusing lens group, switching between an all-pass mode and a pre-screening mode can be realized. According to the arc cylindrical surface ion deflection system for inductively coupled plasma mass spectrometry, on one hand, ion beams generated in an ion source can be effectively separated from neutral substances and photons, on the other hand, the defects of an existing ion deflection system can be overcome, two different deflection modes are achieved, and through implementation of the two deflection modes, the ion deflection efficiency is improved. And a user can flexibly select according to different application fields and different tested samples.

Description

Technical Field

[0001] The present invention relates to the field of inductively coupled plasma mass spectrometers, and in particular to an ion deflection system of a multifunctional inductively coupled plasma mass spectrometer. Background Art

[0002] The typical structure of the inductively coupled plasma mass spectrometry (ICP-MS) system 200 is as follows: Figure 1 As shown, a plasma-based ion source is included; this ion source is used to generate a plasma to break down sample molecules into atoms and then ionize these atoms in preparation for elemental analysis. In typical operation, a liquid sample is atomized, i.e., converted into an aerosol (a fine spray or mist), by a gas-driven (typically argon) nebulizer 201. The coarse aerosol is removed within an atomization chamber 202, and the remaining fine aerosol is directed into a plasma generated by the plasma source. The plasma source is often configured as a flow-through plasma torch 203 having two or more concentric tubes. Typically, a plasma-forming gas (argon) flows through the inner tube of the torch and is excited into a plasma by a suitable energy source, such as radio frequency (RF), powering a load coil 204. The aerosol flows through the coaxial central tube of the torch 203 and is ejected into the generated plasma. Exposure to the plasma breaks down the sample molecules into atoms, or alternatively partially breaks down the sample molecules into molecular fragments and ionizes these atoms or molecular fragments; these ionized analyte atoms or molecular fragments generate an ion beam. Since these ions are not generated in a vacuum region, they gradually transition to a high vacuum region through a sampling cone 205 and a skimmer cone 206. After entering the high vacuum region, the ion beam is focused by an extraction lens 207 and then enters an off-axis or deflection lens 208.

[0003] The plasma used as the ion source for ICP-MS cannot decompose all components in the sample into ions. Some undecomposed neutral substances will be introduced into the subsequent collision reaction cell and quadrupole through the interface along with the ion beam. At the same time, the high-temperature plasma will also produce strong photons. These neutral substances will not only contaminate the subsequent ion mirror and collision reaction cell, but also produce new interfering ions when colliding with the collision reaction gas in the collision reaction cell. Photons will also generate a lot of detection noise. Therefore, an effective means is needed to separate the neutral substances and photons from the analyte ions before the ion beam enters the collision reaction cell. In current commercial instruments, off-axis or deflection methods are usually used to separate the ion beam from the neutral substances and photons.

[0004] Figure 1This is a typical off-axis method. After passing through the off-axis or deflecting lens 208, the ions are separated from the photons and neutral substances, and then enter the collision reaction cell 209. After the interference ions are eliminated by collision or reaction, they are focused by the collision reaction cell exit lens 210 and enter the secondary off-axis lens 211. The off-axis again can eliminate the influence of the neutral substances in the collision reaction cell on the subsequent mass screening, thereby improving the signal-to-noise ratio. After the secondary off-axis, the ion beam enters the mass analyzer 212; the mass analyzer generally adopts a quadrupole structure or other methods such as a sector magnetic field, a time-of-flight (TOF) analyzer, etc., and applies an alternating electric field, or a combination of electric and magnetic fields, so that the ionized ions are spectrally decomposed according to their mass-to-charge ratio m / z, and then the ion detector 213 is able to count each type of ion with a given m / z ratio reaching the ion detector from the mass analyzer. The intensity of each peak indicates the concentration (or abundance) of the corresponding element in the sample.

[0005] In addition to the above-mentioned off-axis method, it is known that in the ICP-MS system, neutral substances and photons are separated from analyte ions by a 90-degree deflection between the ion source and the collision reaction cell. The advantage of the 90-degree deflection is that the large amount of neutral substances generated in the ion source are separated more thoroughly, so that the collision reaction cell can be kept clean for a longer period of time, reducing the performance degradation caused by the contamination of the collision reaction cell, and reducing the cleaning frequency and maintenance costs. The working principle of the existing 90-degree deflection system is as follows: Figure 2 (a) and Figure 2 (b) shown.

[0006] Figure 2 The 90-degree deflection lens shown in (a) uses a single round rod for deflection. Figure 2 (b) illustrates a quadrupole deflection method. The ion beam generated by the ion source gradually transitions to a high vacuum region through sampling cones 301 and 401 and skimmer cones 302 and 402. After entering the high vacuum region, the ion beam is initially focused by extraction lenses 303 and 403. The deflection and focusing lens groups 304 and 404, and 305 and 405 focus the ions onto a single circular rod 306 or the center of the quadrupole 406 deflection lens. After passing through the focal point and being deflected, the ions diverge again. They are then refocused by another symmetrical set of deflection exit focusing lenses 304 and 404, and 305 and 405. These lenses, in conjunction with the collision reaction cell entrance focusing lenses 307 and 407, focus the ions onto the small aperture in the center of the collision reaction cell entrance lenses 308 and 408. After passing through the collision reaction cells 309 and 409, the ions exit through the collision reaction cell exit lenses 310 and 410.

[0007] In ICP-MS, the initial kinetic energy of ions generated by the ion source is inconsistent, generally distributed within 1eV-10eV. The kinetic energy of ions generally increases with the increase of ion mass number (but not in a linear relationship), that is, ions of light-weight elements have lower initial kinetic energy, and ions of heavy-weight elements have higher initial kinetic energy. Figure 2 In the first single rod deflection method shown in (a), all ions within the above-mentioned ion kinetic energy range are deflected at the same time and enter the subsequent collision reaction pool; the advantage of this method is that the ion pass rate is high, all ions use consistent ion mirror parameters, and the tuning is relatively simple, but because the ions cannot be screened to a certain extent, the number of ions entering the collision reaction pool is relatively large, which will cause the collision or reaction efficiency of the collision reaction pool to decrease. Especially when the sample matrix is ​​more complex, it will lead to incomplete elimination of interfering ions, thereby affecting the accuracy of the test results. In addition, this ion deflection method does not have a vertical focusing lens designed, and the ions will produce a certain divergence in the direction perpendicular to the deflection during flight. Especially when the number of ions in the ion beam is large, the mutual thrust between the positive ions will increase this effect. The above-mentioned second method is as follows Figure 2 The quadrupole deflection method shown in (b) is exactly the opposite of the deflection method of a single round rod. It can selectively allow ions with ion kinetic energy within a certain range to pass through by adjusting the DC voltage on the quadrupole, thereby performing a certain amount of pre-screening before the ion beam enters the collision reaction cell, reducing the number of ions entering the collision reaction cell, and thus improving the collision reaction efficiency during sample analysis; however, the disadvantage is that on the one hand, a certain sensitivity will be lost, and on the other hand, during tuning, the deflection electric field curve must be optimized for ions of different mass numbers separately, thereby generating a scanning curve for ion deflection, which increases the complexity of the tuning process.

[0008] In summary, the existing 90-degree ion deflection modes of inductively coupled plasma mass spectrometers each have certain limitations. A more flexible 90-degree ion deflection mode is needed. On the one hand, it can efficiently focus the ions to be measured and complete the 90-degree deflection. At the same time, users can also selectively adopt the "full-pass mode" (all ions are deflected and enter the subsequent collision reaction cell or quadrupole) or "pre-screening mode" (only ions with mass numbers close to the measured ions are deflected and enter the subsequent collision reaction cell or quadrupole) according to their own application needs, thereby making flexible trade-offs in terms of sensitivity, operational convenience and interference elimination capability. Summary of the Invention

[0009] The purpose of the present invention is to solve the problems existing in the prior art and to provide a multifunctional arc cylindrical ion deflection system for inductively coupled plasma mass spectrometry.

[0010] The present invention provides a multifunctional arc-shaped cylindrical ion deflection system for inductively coupled plasma mass spectrometry analysis, comprising a core deflection lens group, an ion focusing lens group and an assembly part;

[0011] The core deflection lens group includes a first arc-shaped cylindrical deflection lens, a second arc-shaped cylindrical deflection lens, and N symmetrically arranged ion kinetic energy adjustment lenses; the first and second arc-shaped cylindrical deflection lenses are concentrically arranged; the outer arc surface of the first arc-shaped cylindrical deflection lens and the inner arc surface of the second arc-shaped cylindrical deflection lens form an ion deflection flight channel;

[0012] The ion focusing lens group comprises N groups of symmetrically arranged entrance or exit focusing lenses, respectively located at the entrance and exit of the ion deflection flight channel; the entrance focusing lens and the exit focusing lens are arranged at a certain angle so as to deflect the flight direction of the ions at the angle; and the center line of the entrance ion focusing lens and the ion kinetic energy adjustment lens intersects with the center line of the exit ion focusing lens group and the ion kinetic energy adjustment lens inside the ion deflection flight channel;

[0013] The assembly part includes a fixed bracket; the core deflection lens group and the ion focusing lens group are fixedly arranged on the fixed bracket.

[0014] Furthermore, the system also includes vertical focusing lenses arranged above and below the ion deflection flight channel formed by the first arc-shaped cylindrical deflection lens and the second arc-shaped cylindrical deflection lens.

[0015] Furthermore, the system also includes a wiring board, and the core deflection lens group and the ion focusing lens group are respectively connected to different positions on the wiring board through connecting wires, so that the required DC voltage is provided to each lens group through the wiring board.

[0016] Furthermore, a first (or first group) DC voltage is applied to the ion focusing lens group; the same second (or second group) DC voltage is applied to the ion kinetic energy adjustment lens and the first arc cylindrical deflection lens; and a third DC voltage is applied to the second arc cylindrical deflection electrode.

[0017] Furthermore, by adjusting the settings of each of the DC voltages, switching between the "pre-screening mode" and the "full-pass mode" is achieved; wherein, when the difference between the first (or first group) DC voltage and the second (or second group) DC voltage is less than a certain voltage value, the deflected flight of ions in the system is in the "pre-screening mode"; when the difference between the first (or first group) DC voltage and the second (or second group) DC voltage is greater than a certain voltage value, the deflected flight of ions in the system is in the "full-pass mode".

[0018] Furthermore, a fourth DC voltage is applied to the vertical focusing lens.

[0019] Furthermore, an opening is provided in the middle of the second arc-shaped cylindrical deflection lens, so that neutral substances and photons generated in the ion source can pass through the opening and fly out of the ion deflection system.

[0020] Furthermore, the inlet or outlet focusing lens and / or the ion kinetic energy adjustment lens is a ring electrode and / or a sheet-shaped or other shaped electrode.

[0021] Furthermore, a round rod electrode is used to replace the first arc-shaped cylindrical deflection lens.

[0022] Furthermore, the focusing lenses at the inlet or outlet are symmetrically or asymmetrically distributed, have the same or different shapes, and are the same or different in number; the ion kinetic energy adjustment lenses at the inlet and outlet are symmetrically or asymmetrically distributed, have the same or different shapes, and are the same or different in number.

[0023] The arc-shaped cylindrical ion deflection system for inductively coupled plasma mass spectrometry provided by the present invention can, on the one hand, effectively separate the ion beam generated in the ion source from neutral matter and photons, and at the same time overcome the shortcomings of existing ion deflection systems and realize two different deflection modes. One is a "screening mode" in which the ions in the ion beam are pre-screened by adjusting the DC voltage applied to the second arc-shaped cylindrical deflection lens 104, so that only ions with a mass number close to that of the analyzed ions are deflected and focused, thereby reducing the number of ions entering the collision reaction cell, improving the efficiency of the collision reaction, reducing interference, and improving the accuracy of the analysis. The other is a "full-pass mode", that is, the DC voltages on all deflection lens groups are fixed, so that ions of all mass numbers are deflected and focused simultaneously, thereby further improving sensitivity and simplifying the optimization process of the ion lens. Through the implementation of these two deflection modes, customers can make flexible choices based on the application field and the different samples being measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a typical schematic diagram of a dual off-axis mode inductively coupled plasma mass spectrometry (ICP-MS) system in the prior art;

[0025] Figure 2 Schematic diagram of the principle of a 90-degree deflection ion lens in the prior art; wherein, Figure 2 (a) Schematic diagram of a single round rod deflected by 90 degrees; Figure 2 (b) Schematic diagram of 90-degree deflection of the quadrupole;

[0026] Figure 3 Schematic diagram of the structure of the arc cylindrical ion deflection system for inductively coupled plasma mass spectrometry analysis in Example 1 of the present invention;

[0027] Figure 4 Schematic diagram of the arc-shaped cylindrical deflection lens structure and ion flight trajectory simulation in Example 1 of the present invention; wherein, Figure 4 (a) is a schematic diagram of the dimensions of the arc cylindrical deflection lens; Figure 4 (b) is a schematic diagram of ion flight trajectory simulation; Figure 4 (c) is a schematic diagram of the structure after the overall assembly is completed;

[0028] Figure 5 This is a schematic diagram of the fixed support structure of the arc-shaped cylindrical ion deflection system of the present invention;

[0029] Figure 6 1 is a circuit connection diagram of the system in the first embodiment of the present invention;

[0030] Figure 7 Schematic diagram of the principle of the arc cylindrical ion deflection system for inductively coupled plasma mass spectrometry analysis in Example 1 of the present invention; wherein, Figure 7 (a) Schematic diagram of the deflection lens and ion flight radius; Figure 7 (b) Schematic diagram of ion flight trajectory in “pre-screening mode”;

[0031] Figure 8 Schematic diagram of the simulation results of ion flight trajectories under two deflection modes in Example 1 of the present invention; wherein, Figure 8 (a) is the simulation result in the “pre-screening” mode; Figure 8 (b) is the simulation result in the “all-pass” mode;

[0032] Figure 9 This is a schematic diagram of the principle of the second embodiment of the present invention;

[0033] Figure 10 This is a schematic diagram of the principle of embodiment 3 of the present invention;

[0034] Figure 11 It is a schematic diagram of the principle of embodiment 4 of the present invention. DETAILED DESCRIPTION

[0035] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "orthogonal", "opposite", "one end", "the other end", etc. used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] The terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed, removable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0038] Example 1

[0039] like Figure 3 As shown, the present invention provides an arc cylindrical ion deflection system 100 for inductively coupled plasma mass spectrometry analysis, which mainly consists of three parts: a core deflection lens group, an ion focusing lens (group) and an assembly part.

[0040] The core deflection lens assembly comprises a first curved cylindrical deflection lens 103, a second curved cylindrical deflection lens 104, and N (N = 1, 2, 3...) symmetrically or asymmetrically arranged annular (or other shaped) ion kinetic energy adjustment lenses 102. Preferably, the core deflection lens assembly may also include two upper and lower vertical focusing lenses 106. The first curved cylindrical deflection lens 103 and the second curved cylindrical deflection lens 104 are concentric in the arc direction; the outer curved surface of the first curved cylindrical deflection lens 103 and the inner curved surface of the second curved cylindrical deflection lens 104 form an ion deflection flight channel.

[0041] The ion focusing lens (group) is composed of N (N=1, 2, 3...) symmetrically or asymmetrically arranged annular (or other shaped) focusing lenses 101, which are respectively located at the entrance and exit of the ion deflection system 100.

[0042] The assembly part mainly includes a fixing bracket 105, a wiring terminal 113, insulating spacers 107, 109 and other assembly components.

[0043] like Figure 3As shown, the entrance or exit focusing lens 101, ion kinetic energy adjustment lens 102, first and second curved cylindrical deflection lenses 103 and 104, and vertical focusing lens 106 are all fixedly mounted on the fixed bracket 105. Furthermore, the entrance focusing lens 101 and the exit focusing lens 101 are arranged at a 90-degree angle. In other embodiments, this angle can be any suitable angle between 0 and 360 degrees. The first and second curved cylindrical deflection lenses 103 and 104 are mounted within the fixed bracket 105 to deflect the ion flight direction by 90 degrees. As shown in the figure, the entrance or exit focusing lens 101 is symmetrically positioned at the entrance and exit ends; the ion kinetic energy adjustment lenses 102 are also symmetrically positioned at the entrance and exit ends. However, in other embodiments, lenses of different shapes, quantities, and configurations can be used at the entrance and exit ends.

[0044] refer to Figure 4 (a) To achieve the objectives of the present invention, the radii of the first and second curved cylindrical deflection lenses 103 and 104 are optimized so that the centerline AB of the entrance ion focusing lens assembly 101 and the ion kinetic energy adjustment lens 102 intersects with the centerline CD of the exit ion focusing lens assembly within the first and second curved cylindrical deflection lenses 103 and 104. Preferably, the center position E of the line connecting the tangent points GH and JK of the first and second curved cylindrical deflection lenses 103 and 104 within the lens assembly corresponds to the center position of the curved cylindrical ion deflection system. Figure 4 Figure (b) shows the ion flight simulation results. By optimizing the voltage of the ion mirror group, the ion beam is perfectly focused at the center E of the deflection lens group. After passing point E, the ion beam begins to diverge before being focused by the exit ion focusing lens 101 to the entrance of the collision reaction cell. The focusing lens at the entrance is used to focus the ion beam entering the deflection lens to the center of the deflection lens, while the focusing lens at the exit is used to focus the deflected ion beam to the subsequent collision reaction cell.

[0045] For the fixing bracket 105, specifically, Figure 5As shown, the fixed bracket 105 of the arc cylindrical ion deflection system 100 includes an upper frame and a lower frame, the upper frame includes two radial edges 105-11, 105-12 and two circular arc edges 105-13, 105-14, the circles corresponding to the two circular arc edges 105-13, 105-14 are concentric circles, and the two radial edges 105-11, 105-12 and the two circular arc edges 105-13, 105-14 form a fan ring shape; the lower frame has the same shape as the upper frame and is vertically spaced a certain distance from the upper frame; between the two radial edges corresponding to the upper and lower frames are the two side elevations 105-2, 105-3 of the fixed bracket 105, and the two side elevations 105-2, 105-3 are perpendicular to each other; between the two circular arc edges corresponding to the upper and lower frames are the two cylindrical surfaces 105-4, 105-5 of the fixed bracket 105.

[0046] Both side surfaces 105-2 and 105-3 are provided with cylindrical protrusions for accommodating the entrance focusing lens, the exit focusing lens 101, and the ion kinetic energy adjustment lens 102. The inner curved cylindrical surface 105-4 is provided with an opening for determining the rotation angle of the first curved cylindrical deflection lens 103. The cylindrical surface 105-5 is also provided with an oblong hole for mounting and securing the second curved cylindrical deflection lens 104.

[0047] The fixing bracket 105 is made of metal or non-metal material. The fixing bracket 105 only plays the role of fixing and supporting other components in the arc-shaped cylindrical ion deflection system 100, and does not directly affect the deflection of ions.

[0048] like Figure 3 As shown, the fixed bracket 105 is an axisymmetric structure, the entrance focusing lens and the exit focusing lens 101, the entrance ion kinetic energy adjustment lens 102 and the exit ion kinetic energy adjustment lens 102 have the same composition and structure. This embodiment does not specifically limit the entrance and exit. During use, one can select one as the entrance and the other as the exit according to the actual installation location and other requirements.

[0049] like Figure 3In the embodiment shown in FIG, the entrance focusing lens, the entrance ion kinetic energy adjustment lens, the exit ion kinetic energy adjustment lens, and the exit focusing lens all include a first circular electrode 101 and a second circular electrode 102; the first circular electrode 101 and the second circular electrode 102 are fixed to the fixing bracket 105. Specifically, the first circular electrode 101 and the insulating ring 107 are fixed to the outside of the columnar accommodation space on the side surface of the fixing bracket 105; the second circular electrode 102 is sleeved within the insulating ring 108 and fixed within the columnar accommodation space on the side surface of the fixing bracket 105.

[0050] The two side elevations of the fixing bracket 105 are perpendicular to each other, and the entrance focusing lens and the exit focusing lens are distributed at 90 degrees.

[0051] Alternatively, the number of annular electrodes of the entrance and exit focusing lenses can be selected according to actual needs.

[0052] The arcuate cylindrical deflecting lens includes a first arcuate cylindrical deflecting lens 103 and a second arcuate cylindrical deflecting lens 104 .

[0053] The first curved cylindrical deflection lens 103 is in the shape of a curved cylinder and is arranged on the inner side of the fixed bracket 105 and fixed to the fixed bracket 105. Specifically, the first curved cylindrical deflection lens 103 is provided with cylindrical protrusions at the upper and lower ends, which are connected to the vertical focusing lens 106 through two upper and lower PEEK insulating gaskets 112, but are not conductive. The connecting wire 114 is also connected to the cylindrical protrusion. The side of the first curved cylindrical deflection lens 103 has two circular holes, which are connected to the inner arc side surface 105-4 of the fixed bracket 105 through a PEEK positioning pin, and are used to position the rotation angle.

[0054] The second curved cylindrical deflection lens 104 is also in the shape of a curved cylinder, with an opening in the middle to allow neutral substances and photons generated in the ion source to pass through. The second curved cylindrical deflection lens 104 is arranged in the fixed bracket 105 and is fixedly connected to the fixed bracket 105 by epoxy resin glue. Specifically, the outer curved surface of the second curved cylindrical deflection lens 104 is connected to the cylindrical surface 105-5 of the fixed bracket 105 by insulating epoxy resin glue, but is not conductive. The second curved cylindrical deflection lens 104 is concentrically arranged with the first curved cylindrical deflection lens 103, and their concentricity is ensured by specially designed assembly tooling.

[0055] An opening is provided at the center of the second cylindrical deflection lens 104 , and the position of the opening corresponds to the position of the opening on the cylindrical surface 105 - 4 , so as to allow neutral substances, photons, etc. to fly out of the arc-shaped cylindrical ion deflection system 100 .

[0056] Preferably, a fan-shaped vertical focusing lens 106 is provided on the outer side of the upper frame and / or the lower frame of the fixing bracket 105 . Figure 3 Figure 1 shows a configuration in which vertical focusing lenses 106 are disposed on the outer sides of both the upper and lower frames of the fixed bracket 105. The vertical focusing lenses 106 are fan-shaped, matching the shape of the fixed bracket 105. An insulating sheet 109 is disposed between the vertical focusing lenses 106 and the fixed bracket 105, and the lenses are secured to the outer sides of the upper and lower frames of the fixed bracket 105 using insulating screws (e.g., nylon or Peek screws). The vertical focusing lenses 106 are used to further focus ions in the arc-shaped cylindrical ion deflection system 100 in both the upper and lower directions.

[0057] Preferably, the bottom of the fixing bracket 105 is fixed on the fixing base 110. Figure 3 As shown, an insulating sheet 111 is provided between the fixed base 110 and the vertical focusing lens 106. The fixed base 110 can dispose the sector-shaped electrostatic field ion deflection lens 100 as a whole at a suitable position of the inductively coupled plasma mass spectrometer.

[0058] The arcuate cylindrical ion deflection system 100 also includes a terminal block 113. Each lens included in the arcuate cylindrical ion deflection system 100, namely, the entrance focusing lens, the exit focusing lens, the first and second arcuate cylindrical deflection lenses, the vertical focusing lens, etc., is connected to a different position on the terminal block 113 via a connecting wire 114. This provides the required DC voltage to each lens through the terminal block 113. Preferably, the terminal block 113 is fixedly connected to the fixing bracket 105 via a terminal block fixing bracket.

[0059] After the ions pass through the entrance focusing lens and enter the arc-shaped cylindrical ion deflection system 100, the flight direction of the ions is deflected by 90 degrees under the joint action of the first arc-shaped cylindrical deflection lens 103 and the second arc-shaped cylindrical deflection lens 104 to which a DC voltage is applied, and the ions fly out from the exit focusing lens. In order to prevent the ion beam from defocusing in the vertical direction during flight, a fan-shaped vertical focusing lens 106 is configured above and below the fan-shaped electrostatic field ion deflection lens 100 to enable the ion beam to be better focused in the vertical direction. Each relevant lens is connected to different positions on the terminal board 113 through a connecting wire 114, so that the required DC voltage is provided to each lens through the terminal board. The specific voltage loading method is as follows. Figure 6 shown.

[0060] like Figure 6As shown, a first DC voltage U1 is applied to the entrance or exit focusing lens 101; the same DC voltage U2 is applied to the ion kinetic energy adjustment lens 102 and the first arc cylindrical deflection lens 103, generally between -10V and -1000V; another set of DC voltages U3 is applied to the second arc cylindrical deflection electrode 104, ranging from +50V to -300V; and a fourth DC voltage U4 is applied to the vertical focusing lens 106.

[0061] Depend on Figure 6 It can be seen that the arc-shaped cylindrical ion deflection system has four sets of DC voltages. By adjusting the settings of each voltage, two different deflection modes can be achieved, namely "pre-screening mode" and "full-pass mode", allowing users to more flexibly select the mode to be used according to the needs of sample analysis.

[0062] The working principle of the arc cylindrical ion deflection system 100 for inductively coupled plasma mass spectrometry analysis of the present invention is described below.

[0063] When ions enter the ion kinetic energy adjustment lens 102 of the core deflection lens assembly of the system 100, they possess a certain initial kinetic energy, typically between 1 and 10 eV (electron volts), with most ions being between 2 and 8 eV. From the center of the ion kinetic energy adjustment lens 102, the ions fly into the ion deflection flight path. Under the influence of the arc-shaped electrostatic field formed by the first and second curved cylindrical deflection lenses 103 and 104, the ions move in an arc along a certain deflection radius. The deflection radius depends on the ion's kinetic energy, flight velocity, and deflection electric field strength, and conforms to the following formula:

[0064]

[0065] Where q is the charge number of the ion, E is the strength of the ion deflection electric field, m is the mass of the ion, v is the flight speed of the ion, and r is the deflection radius of the ion.

[0066] Since the total kinetic energy of the ions So the deflection radius r of ion flight is equal to:

[0067]

[0068] From this, we can see that the ion deflection radius r is independent of the ion's mass, but rather depends on its kinetic energy and the strength of the deflection electric field. Therefore, ions cannot be distinguished by mass while traveling within the deflection electric field, but they can be distinguished by their kinetic energy. In inductively coupled plasma mass spectrometry, the kinetic energy of ions generated by the ion source varies; generally, light-mass ions have lower kinetic energy, while heavy-mass ions have higher kinetic energy. Therefore, this fact can be used to perform preliminary screening of ions in the ion beam.

[0069] In the present invention, reference is made to Figure 7 (a) shows the principle diagram, in which the outer radius of the first curved cylindrical deflection lens 103 is r1, and the inner radius of the second curved cylindrical deflection lens is r2; the ion deflection channel is located in the arc-shaped channel between r1 and r2. Under ideal conditions, ions enter the center of the kinetic energy adjustment lens 102 from the center of the deflection entrance ion focusing lens 101. The DC bias U2 applied to the kinetic energy adjustment lens 102 is more negative than the U1 applied to the entrance or exit focusing lens 101, so the kinetic energy of the ions is increased. Under appropriate deflection electric field strength, ions with a certain kinetic energy will fly along the deflection radius between r1 and r2, that is:

[0070]

[0071] According to the previous formula, the deflection radius of the ion is related to the kinetic energy of the ion and the strength of the deflection electric field; the kinetic energy of the ion E k The initial kinetic energy E generated by the ion source ki and the additional kinetic energy E generated on the kinetic energy regulating lens kU ,Right now:

[0072] E k =E ki +E kU

[0073] Among them, E ki Related to the mass number of the ion, E kU It is related to the voltage difference between the ion kinetic energy adjustment lens 102 and the entrance or exit focusing lens 101. The electric field strength at the intersection of the two ion mirror centers is:

[0074]

[0075] The ions generated by the ion source ICP of the inductively coupled plasma are generally monovalent positive ions, so q = 1. The strength of the deflection electric field E is related to the voltage applied to the first curved cylindrical deflection lens 103 and the second curved cylindrical deflection lens 104, as well as the distance between them:

[0076]

[0077] Wherein, d refers to the distance between the outer arc of the first deflecting lens 103 and the inner arc of the second deflecting lens 104 (d=r2-r1), so:

[0078]

[0079] From this formula we can see that:

[0080] 1) When U1, U2 and U3 are all constant, ions with different kinetic energies will be deflected along different deflection radii;

[0081] 2) When U1 and U2 remain unchanged, ions with different kinetic energies can be deflected to the same radius by simply changing U3;

[0082] 3) The more negative the U2 voltage, the greater the total kinetic energy of the ions, and the closer the deflection radii of ions with adjacent initial kinetic energies. (That is, the more negative the U2 voltage, the smaller the effect of the initial kinetic energy on the ion deflection radius.)

[0083] The present invention is designed based on the above principle. When ions are deflected along the central radius r of the ion deflection flight channel, they can accurately enter the subsequent collision reaction cell focusing lens and be focused into the small hole in the middle of the collision reaction cell entrance lens; when the ion deflection radius is too small or too large, the ions will be deflected to the outside of the collision reaction cell and thus cannot enter the subsequent collision reaction cell (such as Figure 7 By optimizing the aperture of the collision reaction cell focusing lens and the distance between it and the deflection lens, the deviation range of ions allowed to enter the collision reaction cell can be controlled.

[0084] Based on the above design method, the present invention can realize two deflection modes, namely "pre-screening mode" and "all-pass mode" in the same system by changing the voltage applied to different components, which provides great convenience to users.

[0085] In the pre-screening mode, ions with a specific kinetic energy can enter the subsequent collision reaction cell or quadrupole after passing through the system of the present invention; in the full-pass mode, all ions can enter the subsequent collision reaction cell or quadrupole after passing through the system.

[0086] By adjusting the setting of the DC voltage applied to each lens, it is possible to switch between the pre-screening mode and the all-pass mode. Figure 6 Regarding the voltage application method described in [1], when the voltage difference between U1 and U2 is less than a certain voltage value (e.g., 100V, which is related to the mechanical structure and dimensions of the deflection system), the ion deflection flight in the system is in "pre-screening mode." When the voltage difference between U1 and U2 is greater than a certain voltage value (e.g., 100V, which is related to the mechanical structure and dimensions of the deflection system), the ion deflection flight is in "all-pass mode." At the same time, U3 and U4 must be optimized separately for the two different modes. In "pre-screening mode," U3 is optimized based on different ion mass numbers, while in "all-pass mode," U3, like the other voltage groups, is a fixed value. Therefore, by simply changing the optimized values ​​of several voltage groups, switching between two different deflection modes, namely, "pre-screening mode" and "all-pass mode," can be achieved.

[0087] Figure 8 Schematic diagram of the simulation results of ion flight trajectories under two deflection modes in Example 1 of the present invention. Figure 8 (a) is the simulation result in “pre-screening mode”; Figure 8 (b) shows the simulation results in "All-pass mode." The simulation results show that in "Pre-screening mode," when ions with a specific kinetic energy (e.g., 4eV) are selected for analysis, ions with other kinetic energies (e.g., 3eV, 5eV, etc.) are unable to enter the subsequent collision reaction cell or quadrupole. However, when "All-pass mode" is selected, all ions (with kinetic energies between 1eV and 10eV) can enter the subsequent collision reaction cell or quadrupole.

[0088] In actual tests, since not all ions enter the deflection lens along the center of the ion kinetic energy adjustment lens 102, but enter in the form of an ion beam, the actual ion screening efficiency will be slightly lower than the theoretical one, that is, there will still be a small number of ions with adjacent ion kinetic energy that will enter the subsequent collision reaction pool together with the ions with the selected ion kinetic energy, but most of them have been eliminated, which will greatly help to improve the collision reaction efficiency of the ions to be tested in the collision reaction pool, thereby improving the accuracy of complex sample analysis.

[0089] At the same time, because U2 varies significantly between different modes, the vertical focus of ions can also vary. Therefore, the present invention innovatively adds two symmetrical vertical focusing lenses 106 to the curved cylindrical ion transfer lens system. By optimizing the DC voltage U4 applied to these two lenses, the vertical focus of ions is optimized in all modes. This vertical focusing lens 106 also significantly reduces the space charge effect in the analysis of high-matrix samples, effectively improving the internal standard recovery rate of such samples.

[0090] Example 2

[0091] like Figure 9 As shown, this embodiment provides another multifunctional ion deflection system 100 for an inductively coupled plasma mass spectrometer. The ion deflection system 100 of the multifunctional inductively coupled plasma mass spectrometer described in this embodiment is substantially identical in structure to that of the first embodiment, the primary difference being that this embodiment employs a round rod electrode 115 instead of the arc-shaped cylindrical electrode 103 as the first ion deflection lens.

[0092] In this embodiment, the entrance and exit focusing lenses 101, the ion kinetic energy adjustment lens 102, the vertical focusing lens, etc. are all arranged in the same manner as in the first embodiment; the circuit connection method is also basically the same. The advantage of this embodiment is that the cylindrical electrode is easier to process than the curved cylindrical electrode.

[0093] Example 3

[0094] like Figure 10 As shown, the ion deflection system 100 of the multifunctional inductively coupled plasma mass spectrometer in this embodiment is substantially the same in structure as that of the first embodiment, and the main difference between the two is the exit focusing lens.

[0095] In this embodiment, the entrance focusing lens 101, ion kinetic energy adjustment lens 102, vertical focusing lens, etc. are all configured in the same manner as in Example 1. The exit focusing lens uses a sheet electrode 116. The ion beam focused by this electrode directly enters the small hole in the center of the collision reaction cell entrance electrode 117. The sheet electrode 116 is fixedly connected to the fixed bracket 105 using a connection and fixing method commonly used in the art. The collision reaction cell entrance electrode 117 is connected to the collision reaction cell.

[0096] In this embodiment, the outlet focusing lens is set as a sheet electrode, which can reduce the volume of the deflection system, shorten the flight distance of ions from the deflection to the collision reaction cell, and reduce the volume of the vacuum chamber, thereby reducing the cost of the entire machine.

[0097] Example 4

[0098] like Figure 11 The ion deflection system 100 of the multifunctional inductively coupled plasma mass spectrometer in this embodiment is substantially the same in structure as that of the first embodiment, with the main difference between the two being the entrance and exit focusing lenses and the ion kinetic energy adjustment lens.

[0099] In this embodiment, the entrance and exit focusing lenses 101 and the ion kinetic energy adjustment lens 102 all employ sheet electrodes 116 and 118. The ion beam focused by these electrodes directly enters the small hole in the center of the collision reaction cell entrance electrode 117. The sheet electrodes 116 and 118 are fixedly connected to the fixed bracket 105 using a connection and fixing method commonly used in the art. The collision reaction cell entrance electrode 117 is connected to the collision reaction cell.

[0100] In this embodiment, the exit focusing lens and the ion kinetic energy adjustment lens are both configured as sheet electrodes, which can further reduce the volume of the deflection system and the flight distance of ions from the deflection to the collision reaction cell. At the same time, a smaller vacuum chamber can be used, further reducing the cost of the entire machine.

[0101] The above description is only a preferred embodiment of the present invention. It should be noted that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be considered as the scope of protection of the present invention. The basic principles, main features and advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above preferred embodiments. The examples should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0102] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A multifunctional arc-shaped cylindrical ion deflection system for inductively coupled plasma mass spectrometry analysis, comprising a core deflection lens assembly, an ion focusing lens assembly, and an assembly portion; in, The core deflection lens group includes a first arc-shaped cylindrical deflection lens, a second arc-shaped cylindrical deflection lens, and N ion kinetic energy adjustment lenses; the first and second arc-shaped cylindrical deflection lenses are concentrically arranged; The outer arc surface of the first arc-shaped cylindrical deflection lens and the inner arc surface of the second arc-shaped cylindrical deflection lens form an ion deflection flight channel; The ion focusing lens group comprises N groups of symmetrically arranged entrance or exit focusing lenses, respectively located at the entrance and exit of the ion deflection flight channel; the entrance focusing lens and the exit focusing lens are arranged at a certain angle so as to deflect the flight direction of the ions at the angle; and the center line of the entrance ion focusing lens and the ion kinetic energy adjustment lens intersects with the center line of the exit ion focusing lens group and the ion kinetic energy adjustment lens inside the ion deflection flight channel; The assembly part includes a fixed bracket; the core deflection lens group and the ion focusing lens group are fixedly arranged on the fixed bracket.

2. The ion deflection system according to claim 1, wherein: The system further includes vertical focusing lenses arranged above and below the ion deflection flight channel formed by the first arc-shaped cylindrical deflection lens and the second arc-shaped cylindrical deflection lens.

3. The ion deflection system according to claim 1, wherein: The system also includes a wiring board, and the core deflection lens group and the ion focusing lens group are respectively connected to different positions on the wiring board through connecting wires, so that the required DC voltage is provided to each lens group through the wiring board.

4. The ion deflection system according to claim 1, wherein: A first DC voltage or a first group of DC voltages are applied to the ion focusing lens group; a same second DC voltage or a second group of DC voltages are applied to the ion kinetic energy regulating lens and the first arc-shaped cylindrical deflection lens; and a third DC voltage is applied to the second arc-shaped cylindrical deflection lens.

5. The ion deflection system according to claim 4, wherein: By adjusting the settings of each of the DC voltages, switching between "pre-screening mode" and "full-pass mode" is achieved; wherein, when the difference between the first DC voltage or the first group and the second DC voltage or the second group is less than a certain voltage value, the deflection flight of ions in the system is in "pre-screening mode", and at this time the voltage on the second arc-shaped cylindrical deflection lens or other lenses is changed according to the mass number of the analyzed ions; when the difference between the first or the first group of DC voltages and the second or the second group of DC voltages is greater than a certain voltage value, the deflection flight of ions in the system is in "full-pass mode", and at this time the voltages on all other ion lenses and deflection lenses, including the second arc-shaped cylindrical deflection lens, remain unchanged when analyzing all ions.

6. The ion deflection system according to claim 2, wherein: A fourth DC voltage is applied to the vertical focusing lens.

7. The ion deflection system according to claim 1, wherein: An opening is provided in the middle of the second arc-shaped cylindrical deflection lens, so that neutral substances and photons generated in the ion source can pass through the opening and fly out of the ion deflection system.

8. The ion deflection system according to claim 1, wherein: The inlet or outlet focusing lens and / or the ion kinetic energy regulating lens is a ring electrode and / or a sheet electrode.

9. The ion deflection system according to claim 1, wherein: The first arc-shaped cylindrical deflection lens is replaced by a round rod electrode.

10. The ion deflection system according to claim 1, wherein: The focusing lenses at the inlet or outlet are symmetrically or asymmetrically distributed, have the same or different shapes, and are the same or different in number; the ion kinetic energy adjustment lenses at the inlet and outlet are symmetrically or asymmetrically distributed, have the same or different shapes, and are the same or different in number.

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