CN116106397A - Door-free ion mobility spectrometer and ion mobility spectrometry-time-of-flight mass spectrometer - Google Patents
Door-free ion mobility spectrometer and ion mobility spectrometry-time-of-flight mass spectrometer Download PDFInfo
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- CN116106397A CN116106397A CN202111327598.1A CN202111327598A CN116106397A CN 116106397 A CN116106397 A CN 116106397A CN 202111327598 A CN202111327598 A CN 202111327598A CN 116106397 A CN116106397 A CN 116106397A
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- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
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- G—PHYSICS
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- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
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- G01N27/623—Ion mobility spectrometry combined with mass spectrometry
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Abstract
The invention belongs to the technical field of analytical instruments, and particularly relates to a portal-free ion mobility spectrometer and an ion mobility spectrometry-time-of-flight mass spectrometer. The invention relates to a portal-free ion mobility spectrometer, which comprises an ion source, a sample ionization device, an ion introduction electrode, a vacuum cavity and an ion extraction electrode which are sequentially arranged; the vacuum chamber is internally provided with a radial constraint electrode group and an axial pushing electrode group for pushing, dividing and separating ion flow, wherein the axial pushing electrode group comprises an ion flow dividing electrode group and an ion mobility separating electrode group; the ion introducing electrode, the ion flow dividing electrode group, the ion mobility separating electrode group and the ion extracting electrode are sequentially arranged along the movement direction of the ion flow. The invention realizes the ion mobility spectrometer without the ion gate structure and the ion mobility spectrometer-time-of-flight mass spectrometer by using the ion mobility spectrometer without the ion gate structure, and the ion mobility spectrometer can improve the resolution and the sensitivity of the ion mobility spectrometer without the restriction of the ion gate structure, thereby having good application prospect.
Description
Technical Field
The invention belongs to the technical field of analytical instruments, and particularly relates to a portal-free ion mobility spectrometer and an ion mobility spectrometry-time-of-flight mass spectrometer.
Background
Ion mobility spectrometry is an analytical technique based on the fact that gas-phase ions have different migration rates in an axial moving electric field, so that separation detection of substances to be detected is achieved. The sample to be detected ionized by the ion source can realize the analysis and detection of the substance to be detected according to the collision section difference between the formed ions and the background gas. The technology has the advantages of high sensitivity, high detection speed, low price and the like, is widely applied to detection of environmental pollutants, drugs and explosives, and has the potential of separating structural isomers and macromolecular conformation analysis.
Conventional ion mobility spectrometers are generally composed of five major structural components, respectively: an ion source, an ionization region, an ion gate, a transfer region, and a detector. The ion gate is used for cutting a continuous ion flow generated by an ion source into ion slices, and the ion detection utilization rate of the ion mobility spectrometry depends on the pulse duty ratio (1-10%) of the ion gate, so that the sensitivity improvement of the ion mobility spectrometry or the ion mobility spectrometry-time-of-flight mass spectrometry is severely limited. In addition, the resolution (R) of an ion mobility spectrometer is generally defined as:
in the formula (1), T represents the drift time of ions in the drift tube, deltat is the half-peak width of a spectrum peak, T is the temperature of the drift tube, L is the length of the drift tube, E is the electric field intensity, q is the charge amount, and K b Is the boltzmann constant. The pulse width of the ion gate determines the initial ion broadening of the ion sheet into the drift tube, i.e., the half-peak width Δt that ultimately affects the ion mobility spectrometry peak.
According to the principle, to effectively improve the resolution of the ion mobility spectrometer, the pulse duty ratio of the ion gate needs to be further reduced, so that the analysis sensitivity of the ion mobility spectrometer is reduced. Therefore, due to the limitation of the structure of the ion gate, the performance of the traditional ion mobility spectrometer needs to be further improved, and the contradiction exists that the resolution and the sensitivity cannot be considered.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a portal-free ion mobility spectrometer and an ion mobility spectrometer-time-of-flight mass spectrometer combination instrument, which aim at: provided is a portal-free ion mobility spectrometer which can achieve a 100% ion utilization rate and can achieve a synchronous improvement in sensitivity and resolution.
A portal-free ion mobility spectrometer comprises an ion source, a sample ionization device, an ion introduction electrode, a vacuum cavity and an ion extraction electrode which are sequentially arranged; an electrode substrate is arranged in the vacuum cavity, a radial constraint electrode group used for constraining ion flow and an axial pushing electrode group used for pushing, dividing and separating the ion flow are arranged on the electrode substrate, and the axial pushing electrode group comprises an ion flow dividing electrode group and an ion mobility separating electrode group; the ion introducing electrode, the ion flow dividing electrode group, the ion mobility separating electrode group and the ion extracting electrode are sequentially arranged along the movement direction of the ion flow;
the ion flow dividing electrode group comprises at least two ion flow dividing electrodes, the ion flow dividing electrodes in the ion flow dividing electrode group are arranged along the length direction of the main radial constraint electrode, and the distance between the center points of the adjacent ion flow dividing electrodes is 0.1-10 mm; the ion mobility separation electrode group comprises at least two ion mobility separation electrodes, the ion mobility separation electrodes in the ion mobility separation electrode group are arranged along the length direction of the main radial constraint electrode, and the distance between the center points of adjacent ion mobility separation electrodes is 0.1-10 mm.
Preferably, the ion current dividing electrode and the ion mobility separating electrode are respectively rectangular electrode plates with the length of 0.1-10 mm and the width of 0.1-10 mm.
Preferably, the radial constraint electrode group comprises at least two main radial constraint electrodes, the main radial constraint electrodes are in a rod shape, a strip shape or a strip shape, the main radial constraint electrodes are arranged in parallel on a plane, and the arrangement direction of the main radial constraint electrodes is parallel to the movement direction of the ion flow;
the number of the axial pushing electrode groups is at least one, and a group of axial pushing electrode groups is arranged between every two main radial restraining electrodes.
Preferably, the radial constraint electrode group further comprises two auxiliary radial constraint electrodes, the length directions of the auxiliary radial constraint electrodes are parallel to each other, the length directions of the auxiliary radial constraint electrodes are parallel to the main radial constraint electrodes, and the main radial constraint electrodes are arranged between the two auxiliary radial constraint electrodes.
Preferably, the number of the electrode substrates is two, the two electrode substrates are oppositely arranged, the distance between the two electrode substrates is 0.5-10 mm, and the radial constraint electrode groups and the axial pushing electrode groups on the two electrode substrates are arranged in a mirror symmetry mode.
The invention also provides a voltage control method for the portal-free ion mobility spectrometer, wherein radio frequency voltage is applied to the main radial constraint electrodes of the radial constraint electrode group, the phase difference of radio frequency waveforms applied to the adjacent main radial constraint electrodes is 180 degrees, the waveform frequency of the radio frequency voltage is 0.1-10 MHz, and the peak value of voltage oscillation peak is 10-500V;
applying traveling wave voltage to the ion flow dividing electrode group, wherein the waveform frequency of the traveling wave voltage is 0.01-100 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 0.01-1000 m/s;
and a traveling wave voltage is applied to the ion mobility separation electrode group, the waveform frequency of the traveling wave voltage is 1-200 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 1-2000 m/s.
Preferably, the traveling wave voltage is a transient direct current wave, an alternating current wave or a triangular wave.
Preferably, the radial constraint electrode group further comprises an auxiliary radial constraint electrode, wherein a bias direct-current voltage relative to the radio-frequency voltage is applied to the auxiliary radial constraint electrode, and the magnitude of the bias direct-current voltage is 0-1000V.
The invention also provides an ion mobility spectrometry-time-of-flight mass spectrometer, comprising the gateless ion mobility spectrometer and the time-of-flight mass spectrometer according to any one of claims 1-5, wherein an ion extraction opening is arranged on an ion extraction electrode of the gateless ion mobility spectrometer, and the ion extraction opening is connected with an ion extraction slit of the time-of-flight mass spectrometer through an ion guiding device.
The invention also provides a voltage control method for the ion mobility spectrometry-time-of-flight mass spectrometer, which is characterized by comprising the following steps of: the main radial constraint electrodes of the radial constraint electrode group are applied with radio frequency voltages, the phase difference of radio frequency waveforms applied by adjacent main radial constraint electrodes is 180 degrees, the waveform frequency of the radio frequency voltages is 0.1-10 MHz, and the peak value of voltage oscillation peaks is 10-500V;
applying traveling wave voltage to the ion flow dividing electrode group, wherein the waveform frequency of the traveling wave voltage is 0.01-100 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 0.01-1000 m/s;
applying traveling wave voltage to the ion mobility separation electrode group, wherein the waveform frequency of the traveling wave voltage is 1-200 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 1-2000 m/s;
the traveling wave voltage applied to the ion current dividing electrode group is triggered synchronously with the repulsion pulse of the time-of-flight mass spectrometer, and the output time of the time-of-flight mass spectrum repulsion pulse is scanned through a delayer to match ions reaching the time-of-flight mass spectrum repulsion pulse electrode at different times (namely ions with different ion mobility sizes).
In the invention, the ion guiding device belongs to the prior art and is used for ensuring high-quality transmission of ions separated by mobility, and a preferable structure of the ion guiding device is formed by radio frequency multi-stage rod transmission and an electrostatic lens group in a gradient vacuum system.
The invention realizes an ion mobility spectrometer without an ion gate structure and an ion mobility spectrometer-time-of-flight mass spectrometer, and the specific method is to divide a continuous ion flow generated by an ion source into independent ion groups naturally based on a traveling wave technology. When the axial flight speed of the ion clusters driven by the traveling wave is approximately equal to the traveling wave speed, the ions with different collision sections in the ion clusters can be subjected to mobility separation, and then ion detection is performed by using a Faraday cup or a time-of-flight mass spectrometer, so that an ion migration spectrogram or an ion migration spectrogram-time-of-flight mass spectrometry two-dimensional image is obtained. The traditional ion mobility spectrometer only uses part of ions when the ion gate is opened, but the invention successfully removes the structure of the ion gate, so the detection utilization rate of the ion mobility spectrometer is greatly improved, and the resolution and the sensitivity of the instrument are improved at the same time.
It should be apparent that, in light of the foregoing, various modifications, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
The above-described aspects of the present invention will be described in further detail below with reference to specific embodiments in the form of examples. It should not be understood that the scope of the above subject matter of the present invention is limited to the following examples only. All techniques implemented based on the above description of the invention are within the scope of the invention.
Drawings
FIG. 1 is a schematic structural diagram of a gateless ion mobility spectrometer according to embodiment 1 of the present invention;
FIG. 2 is a schematic diagram showing a partial structure of a gateless ion mobility spectrometer according to embodiment 1 of the present invention;
FIG. 3 is a schematic diagram of the working principle of the ion mobility spectrometry-time-of-flight mass spectrometer of the embodiment 2 of the present invention;
FIG. 4 is an ion mobility spectrometry-time-of-flight mass spectrometry selected ion flow addition diagram for acetone and ethyl phenylacetate in example 2 of the present invention;
FIG. 5 is a graph showing the selection of ion mobility spectrometry-time-of-flight mass spectrometry (the traveling wave velocity of the ion separation electrode set is 25m/s, and the traveling wave velocity of the ion mobility separation electrode set is 25 m/s) for acetone and ethyl phenylacetate, respectively, according to example 2 of the present invention;
FIG. 6 is a graph showing the selection of ion mobility spectrometry-time-of-flight mass spectrometry (the traveling wave velocity of the ion separation electrode set is 25m/s, and the traveling wave velocity of the ion mobility separation electrode set is 50 m/s) for acetone and ethyl phenylacetate, respectively, according to example 2 of the present invention;
FIG. 7 is a graph showing the selection of ion mobility spectrometry-time-of-flight mass spectrometry (ion split electrode set traveling wave velocity 25m/s, ion mobility separation electrode set traveling wave velocity 75 m/s) for acetone and ethyl phenylacetate, respectively, in example 2 of the present invention.
The device comprises a 1-ion source, a 2-vacuum extraction opening, a 3-sample inlet, a 4-sample ionization region, a 5-ion inlet electrode, a 6-main radial constraint electrode, a 7-auxiliary radial constraint electrode, an 8-axial pushing electrode group, a 9-ion outlet electrode, a 10-ion flow dividing electrode group, a 11-ion mobility separating electrode group, a 12-electrode substrate, a 13-insulating column and a 14-vacuum cavity.
Detailed Description
Example 1A gateless ion mobility spectrometer
The embodiment provides a portal-free ion mobility spectrometer, which comprises an ion source 1, a sample ionization device, an ion introduction electrode 5, a vacuum cavity 14 and an ion extraction electrode 9 which are sequentially arranged.
The sample ionization device comprises a sample inlet 3 and a sample ionization region 4, and a sample enters the sample ionization region 4 through the sample inlet 3 and is ionized under the action of the ion source 1.
The ion introducing electrode 5 is provided with an ion introducing port, and the ion introducing electrode 5 introduces the sample ionized in the sample ionization region 4 into the vacuum chamber 14 through the ion introducing port by applying a voltage, thereby forming an ion flow of the sample to be measured.
The housing of the vacuum chamber 14 is made of stainless steel or aluminum alloy. In operation, the vacuum chamber 14 is evacuated through a vacuum pumping port 2 at a working pressure of 1Pa to 10000Pa.
An electrode substrate 12 is provided in the vacuum chamber 14, and a radial confinement electrode group for confining the ion flow and an axial push electrode group 8 for pushing, dividing and separating the ion flow are provided on the electrode substrate 12.
The radial constraint electrode group comprises at least two main radial constraint electrodes 6, wherein the main radial constraint electrodes 6 are in a rod shape, a strip shape or a strip shape, the main radial constraint electrodes are specifically selected to be strip shapes made of copper sheets, the length of the main radial constraint electrodes depends on the length of an ion transmission channel, and the main radial constraint electrodes are 100mm in the embodiment. The primary radial confining electrode 6 has a width of 0.43mm. The main radial constraint electrodes 6 are arranged in parallel on a plane, and the arrangement direction of the main radial constraint electrodes 6 is parallel to the movement direction of the ion flow. When the instrument works, radio frequency voltage is applied to the main radial constraint electrodes of the radial constraint electrode groups, the phase difference of radio frequency waveforms applied to adjacent main radial constraint electrodes is 180 degrees, the waveform frequency of the radio frequency voltage is 0.1-10 MHz, and the peak-to-peak value of voltage oscillation is 10-500V, so that ion constraint trap potential is formed.
The radial constraint electrode group further comprises two auxiliary radial constraint electrodes 7, the length directions of the auxiliary radial constraint electrodes 7 are parallel to each other, the length directions of the auxiliary radial constraint electrodes 7 are parallel to the main radial constraint electrodes 6, and the main radial constraint electrodes 6 are arranged between the two auxiliary radial constraint electrodes 7. The auxiliary radial constraint electrode has a length of 100mm and a width of 0.43mm. When the instrument works, the auxiliary radial constraint electrode is applied with a bias direct-current voltage relative to the radio-frequency voltage, and the magnitude of the bias direct-current voltage is 0-1000V.
The number of the axial pushing electrode groups 8 is at least one, and a group of axial pushing electrode groups 8 is arranged between every two main radial restraining electrodes 6. The axial pushing electrode group 8 comprises an ion flow dividing electrode group 10 and an ion mobility separating electrode group 11; the ion introducing electrode 5, the ion flow dividing electrode group 10, the ion mobility separating electrode group 11, and the ion extracting electrode 9 are arranged in this order along the movement direction of the ion flow.
The ion flow dividing electrode group 10 comprises at least two ion flow dividing electrodes, and the ion flow dividing electrodes in the ion flow dividing electrode group 10 are arranged along the length direction of the main radial constraint electrode 6; the ion mobility separation electrode group 11 includes at least two ion mobility separation electrodes, and the ion mobility separation electrodes in the ion mobility separation electrode group 11 are arranged along the length direction of the main radial confinement electrode 6. The ion flow dividing electrode and the ion mobility separating electrode are respectively rectangular electrode plates with the length of 2.25mm and the width of 0.43mm. The center distance of the adjacent ion flux dividing electrode or ion mobility separating electrode is 2.5mm.
The ion flow dividing electrode group is applied with traveling wave voltage, the waveform frequency of the traveling wave voltage is 0.1-200 KHz, the voltage oscillation peak value is 0.1-200V, and the traveling wave voltage is transient direct current wave, alternating current wave or triangular wave.
And traveling wave voltage is applied to the ion mobility separation electrode group, the waveform frequency of the traveling wave voltage is 0.1-200 KHz, the voltage oscillation peak value is 0.1-200V, and the traveling wave voltage is transient direct current wave, alternating current wave or triangular wave.
The setting of the traveling wave speed needs to meet the following conditions:
ion flow splitting electrode group: the travelling wave speed is smaller than the ion flight speed, and the continuous ion flow is gradually blocked in the wave trough of the travelling wave and is divided into independent ion groups;
ion mobility separation electrode group: the traveling wave velocity is equal to or greater than the ion flight velocity, and the segmented ion clusters are gradually separated by mobility.
The traveling wave velocity (m/s) is equal to the center distance (m) of two adjacent traveling wave electrode plates multiplied by the traveling wave frequency (Hz). The axial flying speed of the ions depends on the axial pushing capacity of the traveling wave electric field to the ions and the background air pressure, and the axial pushing capacity of the traveling wave to the ions depends on the length of the traveling wave electrode plate and the traveling wave voltage value.
The wave duty cycle of the travelling wave voltage is equal to 1 divided by the total number of the ion flow dividing electrodes and the ion mobility separating electrodes in each group of the axial pushing electrode groups 8, and the phase difference of the travelling wave voltage on two adjacent electrodes (including the ion flow dividing electrodes and the ion mobility separating electrodes) in the same group of the axial pushing electrode groups 8 is equal to 360 DEG multiplied by the wave duty cycle. For example, when the number of electrodes in the axial pushing electrode group 8 is 4, the waveform duty ratio is 0.25, and the phase difference of the traveling wave voltages on the adjacent two electrodes is 90 °; when the number of electrodes in the axial pushing electrode group 7 is 10, the duty ratio of the waveform is 0.1, and the phase difference of the traveling wave voltages on the adjacent two electrodes is 36 °. By the traveling wave voltage described above, a periodic transient voltage waveform of time-series continuity is generated in the axial pushing electrode group 8, which is capable of pushing the ion beam to move in the axial direction.
The ion flux splitting electrode group 10 is used to split a continuous ion flux into independent ion clusters, and the distribution width of the split ion clusters can be controlled by adjusting the amplitude and the wave velocity of the applied traveling wave voltage.
The ion mobility separation electrode group 11 is used for ion mobility separation of ion clusters, and the amplitude and the wave speed of the applied traveling wave voltage are adjusted so that the axial flying speed of ions driven by the traveling wave electric field is approximately equal to the wave speed of the traveling wave, thereby realizing the separation of the ion clusters separated by the ion mobility separation electrode group (10).
The electrode substrates 12 are made of insulating materials, the number of the electrode substrates 12 is two, the four corners of the two electrode substrates 12 are fixed by insulating columns 13, and the material of the insulating columns 13 is preferably polytetrafluoroethylene, polyether-ether-ketone or ceramic. The two electrode substrates 12 are oppositely arranged, the distance between the two electrode substrates 12 is 3mm, and the radial constraint electrode group and the axial pushing electrode group 8 on the two electrode substrates 12 are arranged in a mirror symmetry mode. In the present embodiment, voltages applied to electrodes (including the main radial confining electrode 6, the auxiliary radial confining electrode 7, the ion flow dividing electrode group 10, and the ion mobility separating electrode group 11) in a mirror-symmetrical relationship are identical.
The ion extraction electrode 9 is provided with an ion extraction port, and the ion flux passes through the vacuum chamber 14, is split into ion clusters by the ion flux splitting electrode group 10, is subjected to mobility separation by the ion mobility separation electrode group 11, and then exits from the ion extraction port to enter the detection device. The detection means may be a faraday cup or a time of flight mass spectrometer or the like.
In this embodiment, the ion inlet and the ion outlet are coaxially arranged, and the area near the axis is the potential well channel of the ion cluster formed by the constraint, segmentation and mobility separation of the main radial constraint electrode 6, the axial pushing electrode group 8 and the auxiliary radial constraint electrode 7 by applying voltage.
It should be noted that, in this embodiment, the shapes and arrangement directions of the main radial confining electrode 6, the axial pushing electrode group 8, and the auxiliary radial confining electrode 7 all satisfy that the length direction is parallel to the movement direction of the ion current. In other embodiments, the main radial confinement electrode 6, the axial pushing electrode set 8, and the auxiliary radial confinement electrode 7 may be designed in other shapes or arrangements as desired, for example, a cyclic ion transfer region structure and a high-resolution ion transfer spectrometer may be designed in a ring shape, as described in reference to "CN 111710586A" in the prior art.
Example 2 ion mobility Spectrometry-time-of-flight Mass Spectrometry
The embodiment provides an ion mobility spectrometry-time-of-flight mass spectrometer, which comprises the gateless ion mobility spectrometer of the embodiment 1 and a time-of-flight mass spectrometer, as shown in fig. 3, wherein an ion extraction port is connected with an ion introduction slit of the time-of-flight mass spectrometer through an ion guiding device. The ion guide is used for ensuring high-quality transmission of the ions separated by mobility, and can be realized based on the prior art. In this embodiment, the ion guide is formed by a radio frequency multi-stage rod transport and an electrostatic lens assembly in a gradient vacuum system.
The traveling wave voltage applied to the ion current segmentation electrode set is triggered synchronously with the repulsion pulse of the time-of-flight mass spectrometer. The output times of the time-of-flight mass spectrometry repulsion pulses are scanned by a delay to match ions arriving at the time-of-flight mass spectrometry pulse electrodes at different times (i.e., ions of different ion mobility sizes). The time required for the ions with large mobility to reach the flight time mass spectrum pulse electrode is short, so that the time for corresponding flight time mass spectrum output delay is short; the time required for the ions with small mobility to reach the time-of-flight mass spectrometry pulse electrode is long, so the time corresponding to the time-of-flight mass spectrometry output delay is long.
The function of dividing continuous ion flow into ion groups in the traditional ion mobility spectrometry is originally realized through an ion gate structure of the ion mobility spectrometry, and the problem of low ion utilization rate (only 1-10%) exists. In the embodiment, the combination of the portal-free ion mobility spectrometer and the time-of-flight mass spectrometer is realized by controlling the traveling wave voltage applied to the ion flow dividing electrode group. The ion utilization rate can be improved to 100%.
In order to demonstrate the technical effect of the present invention, the acetone and ethyl phenylacetate samples were each tested using the ion mobility spectrometry-time-of-flight mass spectrometer of example 2.
FIG. 4 is a graph of the addition of selected ion flows of acetone and ethyl phenylacetate (integration time 1 s), a 50ppbv standard of acetone and ethyl phenylacetate was prepared, wherein the traveling wave velocity was 25m/s for the ion separation electrode set, 25m/s for the ion mobility separation electrode set, the traveling wave amplitude was changed from 1V to 9V (step 1V), and the delay time was changed from 0 μs to 100 μs (step 1 μs); in the test data of the embodiment, the optimal driving voltage of the ions under the low-speed traveling wave is measured to be 4V, and the continuous sample ion flow can be divided into independent ion groups.
FIG. 5 is a graph of the selected ions of acetone and ethyl phenylacetate (integration time 1 s), respectively, and a 50ppbv standard sample of acetone and ethyl phenylacetate was prepared, wherein the traveling wave velocity of the ion separation electrode set was 25m/s, the traveling wave velocity of the ion mobility separation electrode set was 25m/s, the traveling wave amplitude was 4V, and the delay time was changed from 0 μs to 100 μs (step 1 μs); it can be seen that the two sample ions did not create mobility separation within one time-of-flight mass spectrometry pulse repulsion delay period, but there was a significant difference in delay time.
FIG. 6 is a graph of selected ions of acetone and ethyl phenylacetate (integration time 1 s), respectively, prepared into 50ppbv of acetone and ethyl phenylacetate standard samples, wherein the traveling wave velocity of the ion separation electrode set is 25m/s, the traveling wave velocity of the ion mobility separation electrode set is 50m/s, the traveling wave amplitude is 4V, and the delay time is changed from 0 μs to 100 μs (step length 1 μs); it can be seen that the mobility separation of the two sample ions has begun to occur within one time-of-flight mass spectrometry pulse repulsion delay period as the travelling wave velocity increases.
FIG. 7 is a graph of selected ions of acetone and ethyl phenylacetate (integration time 1 s), respectively, prepared into 50ppbv of acetone and ethyl phenylacetate standard samples, wherein the traveling wave velocity of the ion separation electrode set is 25m/s, the traveling wave velocity of the ion mobility separation electrode set is 75m/s, the traveling wave amplitude is 4V, and the delay time is changed from 0 μs to 100 μs (step length 1 μs); it can be seen that the two sample ions further mobility separate with further increase in travelling wave velocity within one time-of-flight mass spectrometry pulse repulsion delay period.
It can be seen that the magnitude of the traveling wave voltage applied to the ion flow dividing electrode group is preferably 4V, the traveling wave speed is preferably 25m/s, and the parameter combination can realize effective ion flow dividing and has higher ion transmission efficiency; the magnitude of the traveling wave voltage applied to the ion mobility separation electrode group is preferably 4V, and the traveling wave velocity is preferably 75m/s, and this combination of parameters enables effective separation of ion mobility.
According to the embodiment, the ion mobility spectrometer without the ion gate structure and the ion mobility spectrometer-time-of-flight mass spectrometer are realized, and the ion mobility spectrometer is not limited by the ion gate structure, so that the ion mobility spectrometer can improve the resolution and the sensitivity of the ion mobility spectrometer in various modes such as improving the ion utilization rate, delaying the scanning of time-of-flight pulse and traveling wave pulse voltage, prolonging the length of a mobility separation tube and the like. Therefore, the invention has good application prospect.
Claims (10)
1. A gateless ion mobility spectrometer, characterized by: comprises an ion source (1), a sample ionization device, an ion introduction electrode (5), a vacuum cavity (14) and an ion extraction electrode (9) which are sequentially arranged; an electrode substrate (12) is arranged in the vacuum cavity (14), a radial constraint electrode group used for constraining ion flow and an axial pushing electrode group (8) used for pushing, dividing and separating the ion flow are arranged on the electrode substrate (12), and the axial pushing electrode group (8) comprises an ion flow dividing electrode group (10) and an ion mobility separating electrode group (11); the ion introducing electrode (5), the ion flow dividing electrode group (10), the ion mobility separating electrode group (11) and the ion extracting electrode (9) are sequentially arranged along the movement direction of the ion flow;
the ion flow dividing electrode group (10) comprises at least two ion flow dividing electrodes, the ion flow dividing electrodes in the ion flow dividing electrode group (10) are arranged along the length direction of the main radial constraint electrode (6), and the distance between the center points of the adjacent ion flow dividing electrodes is 0.1-10 mm; the ion mobility separation electrode group (11) comprises at least two ion mobility separation electrodes, the ion mobility separation electrodes in the ion mobility separation electrode group (11) are arranged along the length direction of the main radial constraint electrode (6), and the distance between the center points of the adjacent ion mobility separation electrodes is 0.1-10 mm.
2. The gateless ion mobility spectrometer of claim 1, wherein: the ion flow dividing electrode and the ion mobility separating electrode are rectangular electrode plates with the length of 0.1-10 mm and the width of 0.01-10 mm respectively.
3. The gateless ion mobility spectrometer of claim 1, wherein: the radial constraint electrode group comprises at least two main radial constraint electrodes (6), the main radial constraint electrodes (6) are in a rod shape, a strip shape or a strip shape, the main radial constraint electrodes (6) are arranged in parallel on a plane, and the arrangement direction of the main radial constraint electrodes (6) is parallel to the movement direction of the ion flow;
the number of the axial pushing electrode groups (8) is at least one, and a group of axial pushing electrode groups (8) are arranged between every two main radial restraining electrodes (6).
4. The gateless ion mobility spectrometer of claim 1, wherein: the radial constraint electrode group further comprises two auxiliary radial constraint electrodes (7), the length directions of the auxiliary radial constraint electrodes (7) are parallel to each other, the length directions of the auxiliary radial constraint electrodes (7) are parallel to the main radial constraint electrodes (6), and the main radial constraint electrodes (6) are arranged between the two auxiliary radial constraint electrodes (7).
5. The gateless ion mobility spectrometer of claim 1, wherein: the number of the electrode substrates (12) is two, the two electrode substrates (12) are oppositely arranged, the distance between the two electrode substrates (12) is 0.5-10 mm, and the radial constraint electrode group and the axial pushing electrode group (8) on the two electrode substrates (12) are arranged in a mirror symmetry mode.
6. A voltage control method for a gateless ion mobility spectrometer according to any one of claims 1 to 5, characterized in that: the main radial constraint electrodes of the radial constraint electrode group are applied with radio frequency voltages, the phase difference of radio frequency waveforms applied by adjacent main radial constraint electrodes is 180 degrees, the waveform frequency of the radio frequency voltages is 0.1-10 MHz, and the peak value of voltage oscillation peaks is 10-500V;
applying traveling wave voltage to the ion flow dividing electrode group, wherein the waveform frequency of the traveling wave voltage is 0.01-100 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 0.01-1000 m/s;
and a traveling wave voltage is applied to the ion mobility separation electrode group, the waveform frequency of the traveling wave voltage is 1-200 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 1-2000 m/s.
7. The voltage control method of claim 6, wherein: the traveling wave voltage is transient direct current wave, alternating current wave or triangular wave.
8. The voltage control method of claim 6, wherein: the radial constraint electrode group further comprises an auxiliary radial constraint electrode, wherein a bias direct-current voltage relative to the radio-frequency voltage is applied to the auxiliary radial constraint electrode, and the magnitude of the bias direct-current voltage is 0-1000V.
9. An ion mobility spectrometry-time-of-flight mass spectrometer, characterized in that: comprising a gateless ion mobility spectrometer according to any of claims 1-5 and a time-of-flight mass spectrometer, an ion extraction opening being provided on an ion extraction electrode (9) of the gateless ion mobility spectrometer, said ion extraction opening being connected to an ion introduction slit of the time-of-flight mass spectrometer by means of an ion guiding device.
10. A voltage control method for the ion mobility spectrometry-time-of-flight mass spectrometer of claim 9, characterized by: the main radial constraint electrodes of the radial constraint electrode group are applied with radio frequency voltages, the phase difference of radio frequency waveforms applied by adjacent main radial constraint electrodes is 180 degrees, the waveform frequency of the radio frequency voltages is 0.1-10 MHz, and the peak value of voltage oscillation peaks is 10-500V;
applying traveling wave voltage to the ion flow dividing electrode group, wherein the waveform frequency of the traveling wave voltage is 0.01-100 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 0.01-1000 m/s;
applying traveling wave voltage to the ion mobility separation electrode group, wherein the waveform frequency of the traveling wave voltage is 1-200 KHz, the voltage oscillation peak value is 0.1-200V, and the wave speed is 1-2000 m/s;
and the traveling wave voltage applied to the ion flow segmentation electrode group is synchronously triggered with the repulsion pulse of the time-of-flight mass spectrometer, and the output time of the time-of-flight mass spectrum repulsion pulse is scanned through a delayer so as to match ions reaching the time-of-flight mass spectrum repulsion pulse electrode at different times.
Priority Applications (2)
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| CN202111327598.1A CN116106397A (en) | 2021-11-10 | 2021-11-10 | Door-free ion mobility spectrometer and ion mobility spectrometry-time-of-flight mass spectrometer |
| PCT/CN2022/129338 WO2023083083A1 (en) | 2021-11-10 | 2022-11-02 | Gateless ion mobility spectrometer and ion mobility spectrometry-time-of-flight mass spectrometer |
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| GB201021360D0 (en) * | 2010-12-16 | 2011-01-26 | Thermo Fisher Scient Bremen Gmbh | Apparatus and methods for ion mobility spectrometry |
| GB201304039D0 (en) * | 2013-03-06 | 2013-04-17 | Micromass Ltd | Time shift improved IMS digitisation |
| US10317364B2 (en) * | 2015-10-07 | 2019-06-11 | Battelle Memorial Institute | Method and apparatus for ion mobility separations utilizing alternating current waveforms |
| CN109003877B (en) * | 2017-06-06 | 2020-10-16 | 岛津分析技术研发（上海）有限公司 | Ion mobility analysis device and analysis method applied to same |
| CN114051428A (en) * | 2019-05-21 | 2022-02-15 | 莫比莱昂系统有限公司 | Voltage control for ion mobility separation |
| JP7452779B2 (en) * | 2019-09-16 | 2024-03-19 | モビリオン・システムズ，インコーポレイテッド | Voltage control for changing characteristics of traveling waves |
| CN111710586A (en) * | 2020-06-15 | 2020-09-25 | 成都西奇仪器有限公司 | Circulating ion migration area structure and high-resolution ion migration spectrometer |
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