A detection method for enhancing ion recognition effect
By setting up an ultrasonic standing wave device in the ion source, the ions are adsorbed and gathered by the standing wave field, which solves the problems of ion loss and mass discrimination effect in electrospray ionization mass spectrometry detection, and improves the detection signal and sensitivity, especially the recognition effect of ions with large mass-to-charge ratio.
Patent Information
- Application Number
- CN202610975704.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-02
- Publication Date
- 2026-08-04
AI Technical Summary
In electrospray ionization mass spectrometry, ions are severely lost during transmission, resulting in weak detection signals. In particular, the detection effect of ions with high mass-to-charge ratio is poor, and there are problems such as mass discrimination effect and insufficient solvent evaporation, which affect the detection sensitivity and accuracy.
An ultrasonic standing wave device is installed in the ion source. An ultrasonic standing wave field is formed by two oppositely arranged acoustic transducer units. The acoustic radiation force generated by the standing wave nodes is used to adsorb and gather ions, forming an ion aggregation channel, which is then directionally transported to the inlet of the mass spectrometer detector. This method is compatible with commercial ion sources and does not require large-scale modification.
It improves ion detection signal and sensitivity, reduces ion loss, and enables effective identification and detection of ions with high mass-to-charge ratio. It also enhances the detection accuracy and sensitivity of biomacromolecules and has a simple structure that is easy to operate and maintain.
Smart Images
Figure CN122506006A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of mass spectrometry analysis and detection technology, and in particular to a detection method for enhancing ion recognition. Background Technology
[0002] Electrospray ionization (ESI) technology, as a typical representative of soft ionization technology, has become an indispensable core ion source technology in the field of mass spectrometry analysis due to its excellent ionization performance on biological macromolecules. It is widely used in many important fields such as biomedicine, environmental monitoring, and food safety.
[0003] The sample is treated by an ESI ion source to form charged droplets. Then, the solvent on the surface of the droplets evaporates. When the Coulomb limit is reached, a Coulomb explosion occurs, forming more and smaller droplets. This process is repeated many times until charged gaseous ions are formed and then enter the inlet of the mass spectrometer detector.
[0004] However, technical defects still exist in the ion transmission process from the ion source to the mass spectrometer detector, affecting the ion detection effect. Specifically: 1. Ions suffer significant losses during transport; After the sample is formed into charged phase ions through the nozzle, it is in a dispersed state and is severely lost during the transport to the mass spectrometer detector. As a result, it cannot be effectively captured by the mass spectrometer, causing problems such as weak ion detection signal and low detection sensitivity, ultimately leading to inaccurate detection results.
[0005] 2. There is an unreasonable quality discrimination effect; Ions with high mass-to-charge ratios are more prone to loss during transport, resulting in poorer detection performance and making effective identification and accurate detection impossible.
[0006] 3. The surface solvent of ions with high mass-to-charge ratio has poor evaporation effect; If the surface solvent of ions is not effectively removed, it will also reduce the detection signal of ions, further reducing the ion detection signal and causing deviation in the detection data.
[0007] The detection sensitivity for biological macromolecules is not high. Summary of the Invention
[0008] This application provides a detection method for enhancing ion recognition without altering the internal structure of the ion source, in order to improve the focusing of sample ions and thus enhance the ion recognition performance of the mass spectrometer detector.
[0009] The above-mentioned technical objective of this application is achieved through the following technical solution: A detection method for enhancing ion recognition includes the following steps: Step 1: Set the ultrasonic standing wave device inside the ion source. The ultrasonic standing wave device includes at least two acoustic transducer units arranged opposite to each other to emit sound waves with the same frequency and opposite propagation directions to superimpose and form an ultrasonic standing wave field. The ultrasonic standing wave device also includes a three-axis adjustment mechanism. Step 2: Two acoustic transducer units extend into the ion source cavity and are located on the left and right sides of the nozzle. The position of the acoustic transducer units is adjusted by the three-axis adjustment mechanism so that the acoustic transducer units are close to the rear of the nozzle and the center height of the acoustic transducer units is lower than the end of the nozzle. Step 3: Adjust the spacing between the two acoustic transducer units using a triaxial adjustment mechanism to create a stable standing wave node in the ultrasonic standing wave field; Step 4: Align the standing wave node with the axial direction of the mass spectrometer detector entrance. Utilize the acoustic radiation force generated by the standing wave node to adsorb and gather ions to form an ion aggregation channel, thereby guiding the ions in the sample to be directionally transported to the mass spectrometer detector entrance.
[0010] Furthermore, the center height of the acoustic transducer unit is 4mm~7mm lower than the tip of the nozzle; The spacing between the two acoustic transducers is set to an integer multiple of half the wavelength; The phases of the two acoustic transducers are set to be either opposite or in phase.
[0011] Furthermore, the ultrasonic standing wave device is installed inside the ion source via a connecting assembly, which includes a detachably connected connecting ring and a support base. The connecting ring is connected to the side wall of the ion source cavity, and the support base is used to support the triaxial adjustment mechanism.
[0012] Furthermore, the triaxial adjustment mechanism is used to adjust the triaxial spatial position of the acoustic transducer unit, including: X-axis adjustment unit used to adjust the depth of the acoustic transducer unit inserted into the ion source cavity; Z-axis adjustment unit used to adjust the height of the acoustic transducer unit; Y-axis adjustment unit used to adjust the distance between two acoustic transducer units.
[0013] Furthermore, the Y-axis adjustment unit includes a transmission assembly, a connecting shell, and a mounting bracket. The transmission assembly is used to drive the two acoustic transducer units to move relative to each other or in the same direction on the connecting shell, and the acoustic transducer units are mounted on the mounting bracket.
[0014] Furthermore, the transmission assembly is used to drive the two acoustic transducer units to slide relative to each other on both sides of the center of the connecting shell, so as to adjust the distance between the two acoustic transducer units. The X-axis adjustment unit is movable on the support base along the Y-axis direction.
[0015] Furthermore, the transmission assembly is used to drive the two acoustic transducers to move in the same direction on the connecting shell, and the distance between the two acoustic transducers on the C-rack is adjustable.
[0016] Furthermore, an infrared indicator light source is provided at the center of the two acoustic transducer units, which is used to emit an axial indicator beam.
[0017] Furthermore, in step 4, after aligning the infrared indicator light source with the axis of the nozzle, the relative position of the standing wave node and the mass spectrometer detector inlet is determined based on the standing wave characteristic point corresponding to the center of the ultrasonic standing wave field, so as to assist in adjusting the position of the standing wave node.
[0018] Furthermore, when the center of the ultrasonic standing wave field formed by the two acoustic transducer units is the anti-node, the position of the ultrasonic standing wave field is adjusted so that the infrared indicator light source deviates from the nozzle to a set distance. When the center of the ultrasonic standing wave field formed by the two acoustic transducer units is the node, the infrared indicator light source is aligned with the axis of the nozzle.
[0019] In summary, this application has the following technical effects: 1. Applying ultrasonic standing wave fields to electrospray ionization mass spectrometry detection, ions are adsorbed and aggregated through the ultrasonic standing wave effect, forming an ion aggregation channel. This reduces ion loss during transport to the mass spectrometer detector inlet. Solvent evaporation occurs during ion transport, comprehensively improving the signal and sensitivity of ion detection. By aligning the standing wave node with the inlet of the mass spectrometer detector, and taking advantage of the characteristic that low sound pressure in the standing wave node corresponds to low gas pressure, ions can be guided to accumulate at high pressure, achieving a precise focusing effect and being directionally delivered to the inlet of the mass spectrometer detector. The position of the acoustic transducer unit is adjustable and can be flexibly changed according to the usage. In particular, placing the acoustic transducer unit behind the nozzle and with its center height 4mm~7mm lower than the nozzle tip can expand the effective range of the standing wave node.
[0020] 2. It can produce a reasonable mass discrimination effect. For ions with a larger mass-to-charge ratio, because their ion mass is larger, they stay longer during the transport process and have more time for solvent evaporation, which can achieve better solvent removal and focusing effects, and enable ions with a large mass-to-charge ratio to be effectively identified and detected.
[0021] In addition, it is also applicable to samples such as biomacromolecules. The standing wave field can enhance the detection effect of biomacromolecules, improving the accuracy and sensitivity of the detection of large biomolecules.
[0022] 3. The ultrasonic standing wave device is compatible with commercial ion sources on the market. It can combine ultrasonic standing wave field with electrospray ionization mass spectrometry detection without large-scale modification of existing ion source equipment. It has a simple structure and is easy to operate and maintain.
[0023] 4. The three-axis adjustment mechanism can adjust the standing wave node to the optimal position to achieve better focusing and solvent removal effects, thereby improving the sensitivity and accuracy of ion detection.
[0024] Under normal conditions, the nozzle in the ion source and the inlet of the mass spectrometer detector are collinearly corresponding. By using the infrared indicator light source to locate the nozzle, the positional relationship between the standing wave node and the inlet of the mass spectrometer detector can be inferred in reverse, so as to better locate the standing wave node. When the center of the ultrasonic standing wave field is the anti-node, the two acoustic transducer units move synchronously with the infrared indicator light source so that the infrared indicator light source is deflected from the nozzle to a set distance. At this time, the standing wave node can correspond to the mass spectrometer detector inlet. When the center of the ultrasonic standing wave field is the node, the two acoustic transducer units and the infrared indicator light source do not need to move. The infrared indicator light source corresponds to the nozzle. At this time, the standing wave node can correspond to the mass spectrometer detector inlet. Attached Figure Description
[0025] Figure 1 This is a schematic diagram showing the positions of the acoustic transducer unit, the nozzle, and the mass spectrometer detector in this application; Figure 2 This is a front view of the acoustic transducer unit of this application; Figure 3 This is a top view of the acoustic transducer unit of this application; Figure 4 This is a schematic diagram of acoustic simulation and schlieren imaging in this application; Figure 5 This is a schematic diagram of the ultrasonic standing wave device structure of this application; Figure 6 This is a schematic diagram showing the interaction between the ultrasonic standing wave device, the ion source, and the mass spectrometer detector of this application; Figure 7 This is a schematic diagram of the explosion of the ultrasonic standing wave device of this application; Figure 8 This is a schematic diagram of the structure of Embodiment 1 of this application; Figure 9 This is a schematic diagram of another embodiment of the relative sliding of the acoustic transducer unit in Embodiment 1 of this application; Figure 10 This is a schematic diagram of the structure of Embodiment 2 of this application; Figure 11 This is a front view of the moving component that drives the three-axis adjustment mechanism to move along the Y-axis in Embodiment 1 of this application; Figure 12 This is a top view of the moving component in Embodiment 1 of this application; Figure 13 This is a front view of the clamping assembly of another embodiment of the three-axis adjustment mechanism that drives the movement along the Y-axis in Embodiment 1 of this application; Figure 14This is a schematic diagram of the operation of the ultrasonic standing wave device of this application; Figure 15 This is a comparison diagram of the mass spectrometry signal intensity of this application; Figure 16 This is a mass spectrum signal intensity diagram of this application under the action of ultrasonic standing waves.
[0026] In the picture: 1. Connecting component; 11. Connecting ring; 12. Support base; 121. Limiting groove; 2. X-axis adjustment unit; 21. X-axis slide; 22. X-axis knob; 3. Z-axis adjustment unit; 31. Connecting frame; 32. Z-axis slide; 33. Z-axis knob; 4. Y-axis adjustment unit; 41. Connecting shell; 411. Slide groove; 412. Placement cavity; 42. Drive rod; 43. Mounting bracket; 44. Y-axis knob; 45. Transmission assembly; 451. Main gear; 452. A driven rack; 453. B driven rack; 454. C is from the rack; 455. Adjustment hole; 456. Worm gear; 457. Worm wheel; 5. Acoustic transducer unit; 6. Infrared indicator light source; 61. Centering rod; 7. Moving component; 71. Adjusting screw; 711. Drive button; 72. Nut seat; 73. Sliding rod; 731. Moving block; 8. Clamping assembly; 81. Limiting frame; 82. Limiting rod; 9. Movable seat. Detailed Implementation
[0027] The present application will be further described in detail below with reference to the accompanying drawings.
[0028] Reference Figures 1 to 16 As shown, a detection method for enhancing ion recognition includes the following steps: Step 1: Connect the connecting ring 11 to the side wall of the ion source so that the ultrasonic standing wave device is set inside the ion source. The ultrasonic standing wave device includes at least two oppositely arranged acoustic transducer units 5, which are used to emit sound waves with the same frequency and opposite propagation directions to superimpose and form an ultrasonic standing wave field. The ultrasonic standing wave device also includes a three-axis adjustment mechanism. Step 2: Two acoustic transducer units 5 extend into the ion source cavity and are located on the left and right sides of the nozzle. The position of the acoustic transducer units 5 is adjusted by the triaxial adjustment mechanism so that the acoustic transducer units 5 are close to the rear of the nozzle and the center height of the acoustic transducer units 5 is lower than the end of the nozzle. This is so that after the sample is ionized by high voltage, the sample ejected by the nozzle can be better adsorbed and focused by the ultrasonic standing wave node, thus expanding the effective range of the standing wave node. Specifically, the center height of the acoustic transducer units 5 is 4mm to 7mm lower than the end of the nozzle. Step 3: Adjust the spacing between the two acoustic transducer units 5 to form a stable standing wave node in the ultrasonic standing wave field. Specifically, set the spacing between the two acoustic transducer units 5 to an integer multiple of half the wavelength, and set the phases of the two acoustic transducer units 5 to be opposite or in-phase. Step 4: Align the standing wave node with the axial direction of the mass spectrometer detector entrance. Utilize the acoustic radiation force generated by the standing wave node to adsorb and gather ions to form an ion aggregation channel, thereby guiding the ions in the sample to be directionally transported to the mass spectrometer detector entrance.
[0029] In step 1: The ultrasonic standing wave device is connected to the side wall of the ion source through the connecting assembly 1, so that the two acoustic transducer units 5 can extend into the ion source cavity. The connecting assembly 1 includes a detachable connecting ring 11 and a support base 12. The connecting ring 11 is detachably connected to the side wall of the ion source cavity. A through hole matching the connecting hole of the ion source side wall is provided around the connecting ring 11. After the bolt passes through the through hole of the connecting ring 11, it is threadedly connected to the connecting hole of the ion source side wall to complete the installation of the ultrasonic standing wave device. A connecting platform extends inward from the lower end of the connecting ring 11. The support base 12 is detachably connected to one side of the connecting platform by bolts, providing a support carrier for the three-axis adjustment mechanism.
[0030] The three-axis adjustment mechanism is used to adjust the three-axis spatial position of the acoustic transducer unit 5, including: The X-axis adjustment unit 2 is used to adjust the depth of the acoustic transducer unit 5 inserted into the ion source cavity; the Z-axis adjustment unit 3 is used to adjust the height of the acoustic transducer unit 5; and the Y-axis adjustment unit 4 is used to adjust the distance between the two acoustic transducer units 5.
[0031] The X-axis adjustment unit 2 includes an X-axis slide 21 mounted on a support base 12. The slider on the X-axis slide 21 is driven by an X-axis knob 22. Specifically, an X-axis threaded rod is rotatably mounted inside the X-axis slide 21. The direction of the X-axis threaded rod matches the X-axis movement path of the corresponding slider. The X-axis threaded rod is threadedly connected to the slider. The X-axis knob 22 is located at the end of the X-axis threaded rod to drive the slider of the X-axis slide 21 to move back and forth.
[0032] Z-axis adjustment unit 3 includes a Z-axis slide 32 mounted on a connecting frame 31. The connecting frame 31 is mounted on the slider of the X-axis slide 21 to be linked with the X-axis adjustment unit 2. The slider on the Z-axis slide 32 is driven by a Z-axis knob 33. Specifically, a Z-axis threaded rod is rotatably mounted inside the Z-axis slide 32. The direction of the Z-axis threaded rod matches the Z-axis movement path of the corresponding slider. The Z-axis threaded rod is threadedly connected to the slider. The Z-axis knob 33 is located at the end of the Z-axis threaded rod to drive the slider of the Z-axis slide 32 to move longitudinally.
[0033] The Y-axis adjustment unit 4 includes a connecting shell 41 mounted on the slider of the Z-axis slide 32, which is linked with the Z-axis adjustment unit 3. The Y-axis adjustment unit 4 also includes a drive rod 42 and a mounting bracket 43 connected to the drive rod 42. A transmission assembly 45 is used to drive the two drive rods 42 to move relative to each other or in the same direction on the connecting shell 41. The connecting shell 41 has through slots at both the upper and lower ends for the drive rods 42 to move. The acoustic transducer unit 5 is mounted on the mounting bracket 43. The transmission assembly 45 is linked with the Y-axis knob 44.
[0034] In other embodiments, the X-axis knob 22, Z-axis knob 33, and Y-axis knob 44 can all be replaced with motors, which are linked to the motors via their output shafts.
[0035] Example 1: When the transmission assembly 45 is used to drive the two acoustic transducer units 5 to slide relative to each other on both sides of the centerline with reference to the centerline of the connecting housing 41: like Figure 8 As shown, two sliding grooves 411 are provided vertically opposite to each other inside the connecting shell 41. The transmission assembly 45 includes a driving part and a transmission part. The driving part is a main gear 451 that can rotate at the center of the connecting shell 41. The transmission part consists of two racks A 452 and B 453 that are respectively offset at the upper and lower ends of the main gear 451. Specifically, rack A 452 can slide in the upper sliding groove, and rack B 453 can slide in the lower sliding groove. Racks A 452 and B 453 are staggered left and right and both mesh with the main gear 451.
[0036] Two drive rods 42 are symmetrical about the center line of the connecting housing 41 and are respectively connected to the rack on the same side. That is, the left drive rod is connected to rack A 452 and the right drive rod is connected to rack B 453. The Y-axis knob 44 passes through the connecting housing 41 and is connected to the main gear 451 to drive the rotation of the main gear 451.
[0037] In another embodiment that drives the two acoustic transducer units 5 to slide relative to each other, such as Figure 9As shown, two sliding grooves 411 are arranged vertically opposite each other inside the connecting shell 41. A slider corresponding to the sliding groove 411 is provided on the drive rod 42 so that both drive rods 42 can slide and engage with the sliding groove 411. A placement cavity 412 for accommodating the transmission component 45 is provided between the two sliding grooves 411. The transmission component 45 includes a drive part and a transmission part. The drive part adopts a worm gear 457 rotatably connected to the connecting shell 41. The worm gear 457 is located on the center line of the connecting shell 41. The transmission part adopts a worm 456 rotatably in the placement cavity 412. The worm 456 meshes with the worm gear 457. A positive thread and a negative thread are respectively provided at both ends of the worm 456. Two drive rods 42 are symmetrically connected to both sides of the worm 456 and are respectively connected to the corresponding threads. The Y-axis knob 44 passes through the connecting shell 41 and is connected to the worm gear 457 to drive the worm gear 457 to rotate.
[0038] In Example 1, when the triaxial adjustment mechanism is moved along the Y-axis to move the two acoustic transducer units 5 in the same direction to adjust the position of the standing wave node: At least two limiting grooves 121 are provided on the support base 12 to match the Y-axis sliding table 21 in the moving path. The bottom of the X-axis sliding table 21 can slide and fit in the limiting grooves 121.
[0039] like Figures 11-12 As shown, the movement of the X-axis slide 21 is driven by the moving assembly 7. The moving assembly 7 includes an adjusting screw 71 rotatable in the front limiting groove 121, a nut seat 72 located at the bottom of the X-axis slide 21, and a moving block 731. The nut seat 72 is threadedly connected to the adjusting screw 71. A drive button 711 is provided at the end of the adjusting screw 71, and the end of the drive button 711 protrudes from the support base 12 for the user to rotate. A sliding rod 73 is provided in the rear limiting groove 121, and the moving block 731 is sleeved on the sliding rod 73. By rotating the drive button 711, the X-axis slide 21 is driven to move the two acoustic transducer units 5 in the same direction.
[0040] In another embodiment that drives the three-axis adjustment mechanism to move along the Y-axis, such as Figure 13 As shown, the movement position of the X-axis slide 21 is restricted by the clamping assembly 8. A movable seat 9 is provided at the bottom of the X-axis slide 21. The movable seat 9 is fitted in the limiting groove 121. The clamping assembly 8 includes a limiting frame 81 that is disposed on both sides of the upper end face of the support base 12 and a limiting rod 82 that is threadedly connected to the limiting frame 81. The ends of the two limiting rods 82 clamp the two sides of the X-axis slide 21 to prevent it from running.
[0041] Example 2: like Figure 10 As shown, when the spacing between the two acoustic transducer units 5 is adjustable, and the transmission assembly 45 is used to drive the two acoustic transducer units 5 to move in the same direction: Two sliding grooves 411 are provided in the connecting shell 41, one above the other. Two drive rods 42 can slide in the upper sliding groove via a slider. The transmission assembly 45 includes a drive part and a transmission part. The drive part is a main gear 451 that can rotate in the center of the connecting shell 41. The transmission part is a C-type rack 454 that can slide in the lower sliding groove. The C-type rack 454 meshes with the main gear 451. The Y-axis knob 44 passes through the connecting shell 41 and is connected to the main gear 451 to drive the rotation of the main gear 451. The C-driven rack 454 has multiple adjustment holes 455. The lower ends of the two drive rods 42 can be detachably connected to the adjustment holes 455 via bolts. By adjusting the connection position of the two drive rods 42 on the C-driven rack 454, the distance between the two drive rods 42 can be changed. The C-driven rack 454 has a numerical scale for selecting the distance value.
[0042] The position of the standing wave node is adjusted by moving the two acoustic transducer units 5 in the same direction via the rack 454 driven by C.
[0043] In Embodiment 2, two drive rods 42 are detachably connected to the C-rack 454, fixing the positions of the two acoustic transducer units 5 on the C-rack 454. The sliding of the C-rack 454 can drive the two acoustic transducer units 5 to move simultaneously along the Y-axis at a fixed interval, thus omitting the setting of the moving component 7 or the clamping component 8 in Embodiment 1.
[0044] The X-axis slide 21, Z-axis slide 32, connecting shell 41 and support base 12 are all provided with scales along their movement path to facilitate precise adjustment of the positions of the two acoustic transducer units 5.
[0045] In step 3: The spacing between the two acoustic transducer units 5 is calculated using the following steps: S01. Set the operating frequency of the acoustic transducer unit 5 and calculate the ultrasonic standing wave wavelength. The formula for calculating the ultrasonic standing wave wavelength is as follows: in, λ is the ultrasonic standing wave wavelength, c is the sound velocity, and f is the frequency of the acoustic transducer unit. S02. Substitute the ultrasonic standing wave wavelength obtained in S01 into the following formula for calculation: Where d is the distance between the two acoustic transducer units. λ is half the wavelength, and n is a multiple of half the wavelength.
[0046] like Figure 4As shown, the left side of the figure is an acoustic simulation performed using 3D AcousticSIM software. The simulation uses a working frequency of 40kHz, and the distance between the two acoustic transducers is 1.5 times the wavelength. The middle and right sides of the figure show gas images generated using a schlieren imaging system. A piece of dry ice is held with tweezers. When the two acoustic transducers are placed vertically or horizontally relative to the dry ice, the sound pressure at the standing wave node formed by the two acoustic transducers is lower than the sound pressure at the anti-standing wave node. The condensed gas produced by the dry ice can be adsorbed and gathered into the channel generated by the standing wave node, which proves that the focusing adsorption effect is optimal when the distance between the two acoustic transducers is 1.5 times the wavelength.
[0047] Based on the observation results of sound field simulation and schlieren experiment, the working frequency of the two acoustic transducer units 5 is set to 40kHz, the sound velocity is 343m / s, and the distance between the two acoustic transducer units 5 is 1.5 times the wavelength. Substituting the frequency and sound velocity of the acoustic transducer units 5 into the formula of S01, the ultrasonic standing wave wavelength is obtained. 1.5 times the wavelength, or 3.5 wavelengths, with n=3, the ultrasonic standing wave wavelength obtained from S01 is substituted into the formula in S02 to obtain: That is, the distance between the two acoustic transducer units is approximately 12.90 mm.
[0048] In this embodiment, two acoustic transducer units 5 are arranged opposite each other. In other embodiments, to enhance the aggregation effect of the ion aggregation channel, multiple sets of corresponding acoustic transducer units 5 can be arranged side by side along the ion transport path. The acoustic transducer unit 5 adopts a piezoelectric ultrasonic transducer, and the shell is made of non-metallic material to avoid damage to the ultrasonic transducer from high voltage when the ion source is working.
[0049] To further locate the standing wave node, an infrared indicator light source 6 is set at the center of the two acoustic transducer units 5 to emit an axial indicator beam. The infrared indicator light source 6 can be an infrared laser diode and is located at the center of the ultrasonic standing wave field.
[0050] In Embodiment 1, when the two acoustic transducer units 5 move relative to each other with respect to the center of the connecting shell 41, the infrared indicator light source 6 is positioned at the center of the upper end of the connecting shell 41, so that it corresponds to the center of the ultrasonic standing wave field. In other embodiments, the infrared indicator light source 6 can also be positioned on the connecting frame 31 or other locations, as long as it is collinear with the center line of the connecting shell 41. The X-axis adjustment unit 2 can be moved along the Y-axis and positioned on the support base 12, thereby driving the standing wave node formed by the two acoustic transducer units 5 to move.
[0051] In Example 2, the spacing between the two acoustic transducer units 5 is first fixed, and then when they move in the same direction within the connecting shell 41 via the transmission assembly 45, centering rods 61 of matching length are connected to the two mounting brackets 43. The infrared indicator light source 6 is set at the center of the centering rod 61 so that it corresponds to the center of the ultrasonic standing wave field.
[0052] In step 4; After aligning the infrared indicator light source 6 with the axis of the nozzle, the relative position of the standing wave node and the mass spectrometer detector inlet is determined based on the standing wave characteristic point corresponding to the center of the ultrasonic standing wave field, i.e., the inverse node or node, so as to assist in adjusting the position of the standing wave node. When the center of the ultrasonic standing wave field formed by the two acoustic transducer units 5 is the anti-node, the position of the ultrasonic standing wave field is adjusted, that is, the two acoustic transducer units 5 are driven to move in the same direction at a fixed interval, so that the infrared indicator light source 6 deviates from the nozzle axis to the set distance. When the center of the ultrasonic standing wave field formed by the two acoustic transducer units 5 is the node, the position of the ultrasonic standing wave field remains unchanged, so that the infrared indicator light source 6 is directly facing the axis of the nozzle.
[0053] In this embodiment, as Figure 3 As shown, the nozzle and the mass spectrometer detector inlet are collinear, and the vertical axis of the nozzle corresponds to the nozzle nozzle. The distance between the two acoustic transducer units 5 is 1.5 times the wavelength, that is, when they are 12.90 mm apart. If the two acoustic transducer units 5 are out of phase, the center of the ultrasonic standing wave field is the anti-node. The position of the ultrasonic standing wave field needs to be adjusted so that the infrared indicator light source 6 deviates from the nozzle to the set distance, that is, the anti-node is driven to deviate from the nozzle to the set distance. Because the axial distance between adjacent nodes and anti-nodes in an ultrasonic standing wave field is The formula for the two acoustic transducers 5 being offset in the same direction is: in, This is the displacement offset. The wavelength of the ultrasonic standing wave; Substituting the ultrasonic standing wave wavelength obtained from S01 into the formula, the offset value of the ultrasonic standing wave field is approximately 2.14 mm. Taking the infrared indicator light source 6 aligned with the nozzle axis as a reference, the ultrasonic standing wave field is offset by 2.14 mm along the Y-axis so that the standing wave node corresponds to the mass spectrometer detector inlet.
[0054] If the two acoustic transducer units 5 are in phase, the center of the ultrasonic standing wave field is the standing wave node. There is no need to adjust the position of the ultrasonic standing wave field; simply make the infrared indicator light source 6 face the nozzle axis.
[0055] In other embodiments, if the nozzle is offset from the mass spectrometer detector inlet in order to make the charged phase ions ejected by the nozzle correspond to the mass spectrometer detector inlet, the offset distance between the nozzle and the mass spectrometer detector inlet must also be considered when calculating the displacement offset.
[0056] The working process for this application is as follows: The ultrasonic standing wave device is placed inside the ion source cavity via connecting component 1; By rotating the X-axis knob 22, the acoustic transducer unit 5 is brought closer to the rear of the nozzle. By rotating the Z-axis knob 33, the center height of the acoustic transducer unit 5 is lower than the tip of the nozzle by 4mm to 7mm. By rotating the Y-axis knob 44, the two drive rods 42 can be moved within the connecting housing 41. The acoustic transducer unit 5 operates at a frequency of 40kHz, with a sound velocity of 343m / s. The spacing between the two acoustic transducer units 5 is 1.5 times the wavelength.
[0057] The method for adjusting the spacing between the two acoustic transducer units is as follows: Example 1: like Figure 8 As shown, rotating the Y-axis knob 44 causes the main gear 451 to mesh with racks A and B, driving racks A and B to move alternately. This causes the two drive rods 42 to move symmetrically on both sides of the center of the connecting shell 41, and the two acoustic transducer units 5 to move relative to each other with the center line of the connecting shell 41 as a reference, that is, to move closer or further away at the same time.
[0058] In another embodiment that drives the relative movement of the two acoustic transducer units 5: like Figure 9 As shown, rotating the Y-axis knob 44 causes the worm gear 456 to rotate through the meshing of the worm wheel 457 and the worm 456. The two drive rods 42 on the positive and negative threads move symmetrically about the center of the connecting shell 41, causing the two acoustic transducer units 5 to move relative to each other with the center line of the connecting shell 41 as a reference, that is, to move closer or further away at the same time.
[0059] The method for driving the three-axis adjustment mechanism to move along the Y-axis is as follows: like Figures 11-12 As shown, the moving component 7 is used, and by turning the drive button 711, the X-axis slide 21 drives the entire three-axis adjustment mechanism to move along the Y-axis direction.
[0060] In another embodiment that drives the three-axis adjustment mechanism to move along the Y-axis, such as Figure 13 As shown, by using the clamping assembly 8, the X-axis slide 21 is first slid to the desired position, and then the limiting rods 82 on both sides are tightened so that the limiting rods 82 on both sides abut against the sides of the X-axis slide 21 to prevent it from moving.
[0061] Example 2: like Figure 10 As shown, the two drive rods 42 are connected to the corresponding adjustment holes 455 at the required spacing to fix the positions of the two acoustic transducer units 5.
[0062] The method for adjusting the two acoustic transducer units 5 to move along the Y direction with a fixed spacing is as follows: When the distance between the two acoustic transducer units 5 is fixed and they can move in the same direction, rotating the Y-axis knob 44 drives the two acoustic transducer units 5 to move in the same direction with a fixed distance through the meshing of the main gear 451 and the C-driven rack 454.
[0063] The above adjustment steps have achieved the technical effect required by this application, and are for further precise adjustment of the position of the standing wave node.
[0064] Align the infrared indicator light source 6 with the axis of the nozzle; If the center of the ultrasonic standing wave field formed by the two acoustic transducer units 5 is the anti-node, then adjust the moving path of the two acoustic transducer units 5 with fixed spacing in the Y-axis direction so that the center of the ultrasonic standing wave field is offset by 2.14mm. If the center of the ultrasonic standing wave field formed by the two acoustic transducer units 5 is a node, then the positions of the two acoustic transducer units 5 remain unchanged.
[0065] like Figure 14 As shown, the standing wave node is aligned with the mass spectrometer detector inlet, forming an ion aggregation channel through the standing wave node. Under the action of a high-voltage electric field, the nozzle ejects charged droplets, which are adsorbed into the ion aggregation channel. Then, the solvent on the droplet surface evaporates. When the Coulomb repulsion between charges exceeds the surface tension of the droplet, a Coulomb explosion occurs, forming more and smaller droplets until charged gaseous ions are formed and enter the mass spectrometer detector inlet.
[0066] The beneficial effects of this application are as follows: like Figure 15 The image shows an intensity comparison of the mass spectrometry signal. The test points are the mass-to-charge ratios of three features: 132 Da, 415 Da, and 829 Da. Without the support of ultrasonic standing waves, the signal intensity is as follows: Figure 15 As shown by the dashed line, the measured mass-to-charge ratio and signal intensity are close to 0, with only a weak response at 829 Da. With the aid of ultrasonic standing waves, such as Figure 15 As shown by the solid line, strong signals were detected at all three mass-to-charge ratios, and the signal intensity increased exponentially with the increase of the mass-to-charge ratio. Among them, the signal increase of 829 Da was much higher than that of 132 Da and 415 Da, which proved that the larger the mass of the ion, the stronger the focusing effect in the ultrasonic standing wave field, the smaller the transmission loss, and therefore the more significant the signal increase, i.e., there is a mass discrimination effect.
[0067] like Figure 16The figure shows the mass spectrum signal intensity under the action of ultrasonic standing waves. The test points are the mass-to-charge ratios of three features: 132 Da, 415 Da, and 829 Da. The detection results of the three test points are verified by three sets of experimental data EXP1, EXP2, and EXP3. The signal enhancement at the test point of 829 Da is much higher than that of the other two, which further verifies that there is a reasonable mass discrimination effect of ultrasonic standing waves.
[0068] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A detection method for enhancing ion recognition, characterized in that, Includes the following steps: Step 1: Connect the connecting ring (11) to the side wall of the ion source so that the ultrasonic standing wave device is set inside the ion source. The ultrasonic standing wave device includes at least two acoustic transducer units (5) arranged opposite to each other to emit sound waves with the same frequency and opposite propagation direction to superimpose and form an ultrasonic standing wave field. The ultrasonic standing wave device also includes a three-axis adjustment mechanism. Step 2: The two acoustic transducer units (5) are inserted into the ion source cavity and located on the left and right sides of the nozzle. The position of the acoustic transducer units (5) is adjusted by the three-axis adjustment mechanism so that the acoustic transducer units (5) are close to the rear of the nozzle and the center height of the acoustic transducer units (5) is lower than the end of the nozzle. Step 3: Adjust the spacing between the two acoustic transducer units (5) using the triaxial adjustment mechanism to form a stable standing wave node in the ultrasonic standing wave field; Step 4: Align the standing wave node with the axial direction of the mass spectrometer detector entrance. Utilize the acoustic radiation force generated by the standing wave node to adsorb and gather ions to form an ion aggregation channel, thereby guiding the ions in the sample to be directionally transported to the mass spectrometer detector entrance.
2. The detection method for enhancing ion recognition effect according to claim 1, characterized in that: The center height of the acoustic transducer unit (5) is 4mm~7mm lower than the tip of the nozzle; The spacing between the two acoustic transducer units (5) is set to be an integer multiple of half the wavelength; The phases of the two acoustic transducers (5) are set to be either opposite or in phase.
3. The detection method for enhancing ion recognition effect according to claim 1, characterized in that: The connecting assembly (1) includes a detachably connected connecting ring (11) and a support base (12), which is used to support the triaxial adjustment mechanism.
4. The detection method for enhancing ion recognition effect according to claim 1, characterized in that: The three-axis adjustment mechanism is used to adjust the three-axis spatial position of the acoustic transducer unit (5), including: X-direction adjustment unit (2) for adjusting the depth of the acoustic transducer (5) inserted into the ion source cavity; Z-axis adjustment unit (3) used to adjust the height of acoustic transducer (5); Y-axis adjustment unit (4) for adjusting the spacing between two acoustic transducer units (5).
5. The detection method for enhancing ion recognition effect according to claim 4, characterized in that: The Y-axis adjustment unit (4) includes a transmission assembly (45), a connecting shell (41), and a mounting bracket (43). The transmission assembly (45) is used to drive two acoustic transducer units (5) to move relative to each other or in the same direction on the connecting shell (41). The acoustic transducer units (5) are mounted on the mounting bracket (43).
6. The detection method for enhancing ion recognition effect according to claim 5, characterized in that: The transmission assembly (45) is used to drive the two acoustic transducer units (5) to slide relative to each other on both sides of the center of the connecting shell (41) to adjust the distance between the two acoustic transducer units (5). The X-axis adjustment unit (2) is movable on the support base (12) along the Y-axis.
7. The detection method for enhancing ion recognition effect according to claim 5, characterized in that: The transmission assembly (45) is used to drive the two acoustic transducers (5) to move in the same direction on the connecting shell (41), and the distance between the two acoustic transducers (5) on the rack (454) is adjustable.
8. The detection method for enhancing ion recognition effect according to claim 1, characterized in that: An infrared indicator light source (6) is provided at the center of each of the two acoustic transducer units (5). The infrared indicator light source (6) is used to emit an axial indicator beam.
9. The detection method for enhancing ion recognition effect according to claim 8, characterized in that: In step 4, after aligning the infrared indicator light source (6) with the axis of the nozzle, the relative position of the standing wave node and the mass spectrometer detector inlet is determined based on the standing wave characteristic point corresponding to the center of the ultrasonic standing wave field, so as to assist in adjusting the position of the standing wave node.
10. The detection method for enhancing ion recognition effect according to claim 9, characterized in that: When the center of the ultrasonic standing wave field formed by the two acoustic transducer units (5) is the anti-node, adjust the position of the ultrasonic standing wave field so that the infrared indicator light source (6) deviates from the nozzle axis to the set distance. When the center of the ultrasonic standing wave field formed by the two acoustic transducer units (5) is the node, the infrared indicator light source (6) is aligned with the axis of the nozzle.