CN118209620A - Ion mobility analysis device - Google Patents
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- 238000004458 analytical method Methods 0.000 title claims abstract description 105
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- 238000001871 ion mobility spectroscopy Methods 0.000 description 12
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- 238000005040 ion trap Methods 0.000 description 5
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- 239000003153 chemical reaction reagent Substances 0.000 description 2
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- 238000000951 ion mobility spectrometry-mass spectrometry Methods 0.000 description 2
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- HBAQYPYDRFILMT-UHFFFAOYSA-N 8-[3-(1-cyclopropylpyrazol-4-yl)-1H-pyrazolo[4,3-d]pyrimidin-5-yl]-3-methyl-3,8-diazabicyclo[3.2.1]octan-2-one Chemical class C1(CC1)N1N=CC(=C1)C1=NNC2=C1N=C(N=C2)N1C2C(N(CC1CC2)C)=O HBAQYPYDRFILMT-UHFFFAOYSA-N 0.000 description 1
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- G01N27/622—Ion mobility spectrometry
- G01N27/623—Ion mobility spectrometry combined with mass spectrometry
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- H01J49/0422—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components for gaseous samples
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
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Abstract
The invention relates to an ion mobility analysis device, which comprises an ion source; an analysis channel; an electrode array comprising a series of electrode sets arranged along the extension of the analysis channel; a DC power supply device for applying a gradient voltage to the electrode array to form an electromigration-driven DC electric field in the analysis channel; the first high-frequency power supply device is used for generating n high-frequency signals with the same frequency and different phases, and the n high-frequency signals are sequentially output to n pole pieces circumferentially arranged in the multi-row electrode group according to the phase sequence, wherein n is more than or equal to 3, so that a high-frequency electric field for rotating ions is generated. According to the invention, the traction electric field and the rotation electric field are applied to the ions, so that the ions do migration motion while rotating around the migration axis, and chiral enantiomer ions with small structural differences can have mobility differences during the same-direction rotation and same-direction electromigration, so that space or time separation is generated, the purpose of directly analyzing chiral molecules by ion migration spectrum is realized, and the analysis efficiency is improved.
Description
Technical Field
The invention relates to the technical field of molecular detection and diagnosis devices, in particular to an ion mobility analysis device.
Background
Ion mobility spectrometry (Ion Mobility Spectrometry, IMS, also known as ion mobility) is a detection technique developed at the end of the 60 s of the 20 th century, and has proven to be a powerful tool for rapidly identifying isomerised ions, which are separated in an electric field by a neutral gas medium, according to their different conformations and differences in their collision cross-section (Collision Cross Section, CCS) with the gas molecules. The working principle is that target molecules enter a drift tube (drift tube) with certain gas density after ionization, a certain axial electric field is arranged in the tube, ions are driven to electrically migrate towards one end, and different ions sequentially reach a detector according to different mobilities of the ions, so that a migration spectrum is formed.
In the prior art, IMS is often combined with mass spectrum (Mass Spectrometry) to form an IMS-MS device, which increases a mobility separation dimension on the basis of mass spectrum technology and improves the structural separation and measurement of ions; meanwhile, the special function of ion selection is enhanced in mobility technology, so that ion separation has high selectivity. Currently, IMS-MS has been highly accepted and widely used in the fields of explosive detection, industrial production, life science research, atmospheric pollutant monitoring, and the like. However, molecules with small structural differences cannot be identified by ion mobility spectrometry, because under normal conditions, the collision cross section of molecules with small structural differences (such as different chiral isomer ions) and gas molecules in a migration tube are substantially the same, and cannot cause mobility differences. Therefore, when the chiral isomer molecules are separated and identified by ion mobility spectrometry, it is generally necessary to add a separation reagent to convert the molecules with small structural differences into complexes with large structural differences. This method has a certain feasibility but the separation reagent does not have general applicability and is largely limited for complex analysis samples.
Chinese patent document CN117012611a discloses an ion trap mass spectrometer, in which a double Alternating Current (AC) dipole voltage is used to drive ions to directionally rotate and resonantly excite, that is, dipole excitation with a phase difference is adopted in the X and Y directions, so that the difference in collision cross-sectional area is generated for enantiomer ions in the process of ion cloud scanning analysis, and chiral enantiomer ions are distinguished by scanning excitation oscillation voltage. The linear ion trap is used as a miniaturized mass spectrum, and has the advantages of small instrument and flexible analysis; however, the ion cloud scanning function of the linear ion trap is used for chiral molecular analysis, the adopted air pressure is very low (10 -5 Torr), the collision frequency of ions and gas molecules is low, the analysis speed is slower, in addition, the even-level excitation frequency in the ion trap needs to meet a specific relation with the mass of the ions, so that even-level excitation can be realized, and the ion rotation frequency cannot be adjusted; in addition, the adoption of a chiral separation method of radial ejection is inconvenient for tandem mass spectrometry after migration spectrometry.
Disclosure of Invention
In view of the shortcomings of the prior art, the main object of the present invention is to provide an ion mobility analysis device capable of directly analyzing molecules with small structural differences, even mirror symmetry molecules such as chiral isomer molecules.
In order to achieve the above object, the present invention provides an ion mobility analysis apparatus comprising
An ion source;
An analysis channel filled with a gas and extending along an ion electromigration direction;
an electrode array comprising a series of electrode sets arranged along the extension of the analysis channel;
A dc power supply device connected to each of the electrode groups for applying a gradient voltage across the electrode array to form an electrotransport drive dc electric field within the analysis channel;
The first high-frequency power supply device is connected with a plurality of rows of electrode groups in the electrode array, the electrode groups connected with the first high-frequency power supply device comprise n pole pieces which are circumferentially arranged around the analysis channel, n is more than or equal to 3, the first high-frequency power supply device is used for generating n high-frequency signals which have the same frequency and different phases, and n high-frequency signals are sequentially output to the n pole pieces which are circumferentially arranged according to the phase sequence so as to generate a high-frequency electric field for rotating ions.
The working principle of the invention is as follows: according to the invention, a traction electric field and a rotation electric field are applied to the ions, so that the ions can perform migration movement while rotating around a migration axis, wherein the ion rotates around the migration axis and comprises revolution of a centroid and autorotation of a charge end around the centroid, the rotation speed can be freely adjusted, and chiral enantiomer ions can have mobility differences when rotating in the same direction and electromigration in the same direction relative to medium gas, thereby generating space or time separation, the separated ions can be detected by a subsequent ion detection device, the purpose of directly analyzing chiral molecules by ion mobility spectrometry is realized, and the analysis efficiency is improved.
Preferably, n=4, the first high-frequency power supply device generates 4 high-frequency signals with different phases, and the phase sequence of each high-frequency signal is 0, pi/2, pi, 3 pi/2, and the signals are output to the 4 pole pieces circumferentially arranged in the electrode group in circumferential sequence. By applying dipole voltages with a phase difference to adjacent electrode pairs, a radially rotating electric field can be generated in the analysis channel, driving the ions to rotate directionally, thereby differentiating ions of chiral molecules.
Preferably, n=3, the first high-frequency power supply device generates 3 high-frequency signals with different phases, and the phase sequence of each high-frequency signal is 0, pi/3, 2 pi/3, and the signals are output to the 3 pole pieces circumferentially arranged in the electrode group in circumferential sequence. The invention provides a plurality of generation modes of rotating electric fields, and the rotating electric fields can be formed by applying voltages with different phases to all pole pieces arranged in the circumferential direction.
Preferably, the output signal frequency of the first high-frequency power supply device is between 100kHz and 100 MHz. The chiral molecules have a certain rotation speed to realize effective separation in the electromigration process, and the ion rotation speed can be freely adjusted by adjusting the output signal frequency of the first high-frequency power supply device so as to adapt to the requirements of different ion separations.
Preferably, the ion analyzer comprises a second high-frequency power supply device, wherein the second high-frequency power supply device is connected with a plurality of rows of electrode groups in the electrode array, the electrode groups connected with the second high-frequency power supply device comprise 2m electrode plates circumferentially arranged around the analysis channel, the second high-frequency power supply device provides a pair of radio-frequency voltages with opposite polarities, one of the radio-frequency voltages is output to the electrode plates with odd circumferential numbers, the other radio-frequency voltage is output to the electrode plates with even circumferential numbers, a multipole field for restraining ions in the radial direction is generated, and the ions are prevented from being radially diffused.
Preferably, m=2, the second high-frequency power supply device applies radio-frequency voltages with opposite polarities to the two pairs of pole pieces, and generates a radio-frequency multipole electric field with a quadrupole field as a main component.
Preferably, each row of electrode groups comprises four electrode plates circumferentially arranged around the analysis channel, namely a first electrode plate, a second electrode plate, a third electrode plate and a fourth electrode plate, the first high-frequency power supply device generates four high-frequency signals with phases of 0, pi/2, pi and 3 pi/2 respectively, the first high-frequency power supply device is connected in series through a high-frequency transformer winding, the high-frequency signals with phases of 0 and pi are superposed on a radio-frequency voltage with one polarity generated by the second high-frequency power supply device, the second electrode plate and the fourth electrode plate are respectively supplied, the first high-frequency power supply device is connected in series through a high-frequency transformer winding, the high-frequency signals with phases of pi/2 and 3 pi/2 are superposed on a radio-frequency voltage with the other polarity generated by the second high-frequency power supply device, the third electrode plate and the first electrode plate are respectively supplied, and each row of the electrode groups simultaneously generates a radial rotating electric field and a field for ion confinement.
Preferably, the ion mobility analysis device comprises a gas flow control device for enabling the gas to form a directional gas flow in the analysis channel, wherein the direction of the directional gas flow is opposite to the direction of the electromigration driving direct current electric field. The reverse airflow in the opposite direction of the traction electric field can increase the effective drift length of ions, and the electric field strength is increased in a gradient way along the extending direction of the migration analysis channel, so that ions with different mobilities can be gathered at different positions due to the offset of the migration speed and the airflow speed, and the resolution of the ion migration spectrum is improved.
Preferably, the analysis channel is linear or curved.
Preferably, the analysis channel comprises a first channel and a second channel, and an outlet of the first channel and an inlet of the second channel are communicated through a side hole channel.
The shape of the analysis channels is optimized, or the number of the analysis channels is increased, so that the effective drift length can be increased in a limited space, and the resolution of the ion mobility spectrometry can be improved.
Preferably, the dc power supply device includes a dc power supply and a voltage dividing resistor string connected to the dc power supply, and the dc power supply device outputs a desired dc voltage to each node in the electrode array by dividing the voltage by the voltage dividing resistor string. The direct current migration driving voltage is obtained by adopting voltage dividing resistors, so that the number of direct current power supplies can be reduced.
Preferably, the dc power supply device includes a DA converter and a dc amplifier, and the DA converter supplies a variable dc voltage, and the dc amplifier outputs a desired dc voltage to each of the electrode groups in the electrode array. The DA converter provides a variable direct current voltage, which is convenient for voltage regulation.
Preferably, the ion mobility analysis device further comprises an ion detection device disposed at the end of the analysis channel.
Preferably, the ion detection device comprises a mass spectrometer. Ion mobility spectrometry and mass spectrometry are used in series, so that multidimensional separation of ions is realized, and the analysis certainty is improved.
Drawings
Fig. 1 is a schematic structural view of an ion mobility analysis apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a power-up mode structure of an electrode array according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of the power-up mode and the electric field rotation mode of the electrode group according to the embodiment of the present invention.
Fig. 4 is a schematic diagram of a power-up mode of an electrode set according to another embodiment of the present invention.
FIG. 5 is a schematic diagram showing the structure of the electrode array in a power-on mode according to another embodiment of the present invention.
FIG. 6 is a schematic diagram showing the structure of the electrode array in a power-on mode according to another embodiment of the present invention.
Fig. 7 is a schematic diagram of a power-up mode of an electrode set according to another embodiment of the present invention.
FIG. 8 is a schematic representation of the change in the cross-section of the opposite chiral enantiomer impinging on an axially flown gas stream molecule upon rotation.
Reference numerals:
1-electrode array, 10-electrode group, 11-first pole piece, 12-second pole piece, 13-third pole piece, 14-fourth pole piece, 22-radio frequency power supply, 23-third transformer, 25-voltage dividing resistor, 261-first blocking capacitor, 262-second blocking capacitor, 263-third blocking capacitor, 264-fourth blocking capacitor, 265-fifth blocking capacitor, 266-sixth blocking capacitor, 267-seventh blocking capacitor, 271-first switch driving circuit, 272-second switch driving circuit, 273-third switch driving circuit, 281-first resistor, 282-second resistor, 283-third resistor, 284-fourth resistor, 285-fifth resistor, 286-sixth resistor, 287-seventh resistor, 31-first high frequency power supply, 32-second high frequency power supply, 33-first transformer, 34-second transformer, 41-directional gas flow, 42-electromigration driving force, 5-ion source, 6-ion detection device, 80-first blade, 82-second blade.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
Embodiments of the present invention provide an ion mobility analysis device that is an important improvement over existing ion mobility spectrometry that can be used to directly analyze enantiomer molecules that are mirror-symmetrical in structure.
As shown in fig. 1 to 3, the ion mobility analysis apparatus of the present embodiment includes an ion source 5, an analysis channel, an electrode array 1, and an ion detection apparatus 6. The ion source 5 is used for converting molecules to be analyzed into charged ions; the analysis channel extends along the ion electromigration direction, and is filled with medium gas, and the pressure of the medium gas is between 1mTorr and 1 atmosphere; the electrode array 1 comprises a series of electrode sets 10 arranged around an analysis channel, each electrode set 10 being arranged along the extension direction of the analysis channel; an ion detection device 6 is provided at the end of the electrode array 1 for detecting ions. The ion mobility analysis apparatus further comprises a dc power supply device connected to each row of electrode sets 10 for applying a gradient voltage across the electrode array 1 to form an electromigration-driven dc electric field within the analysis pathway. In operation, each row of electrode sets 10 is sequentially supplied with a voltage V 1、V2、V3......VN. When positive ions are analyzed, these voltages drop stepwise, creating an electric field in the analysis channel from left to right in the figure, driving the ions to electromigration to the right. The dc power supply device may include a plurality of dc power supplies, or may supply only the voltages V 1 and V N at both ends, and the intermediate electrode group 10 may include a plurality of voltage dividing resistors 25 to form a voltage dividing resistor string to generate a desired voltage division. The ion mobility analysis device operates as follows: ions collide with gas molecules in the moving process, ions with smaller collision cross sections have higher mobility, the speed of the moving motion is faster, and the ions reach the ion detection device 6 first; on the other hand, ions having a large collision cross section have smaller mobility and lower movement speed, and reach the ion detection device 6 later, so that ions having different structures can be distinguished by the difference in mobility.
In order to distinguish ions of chiral isomer molecules, the ion mobility analysis apparatus of the present embodiment includes a first high-frequency power supply device for forming a high-frequency electric field for rotating ions in an analysis channel to analyze the direction of the ion electromigration direction rotation axis in the channel. As shown in fig. 2 and 3, in the present embodiment, a first high-frequency power supply device is connected to each electrode group 10 (the connection lines of the electrode groups 10 in the middle portion of fig. 2 are not all drawn due to shielding), each electrode group 10 includes four pole pieces, which are sequentially named as a first pole piece 11, a second pole piece 12, a third pole piece 13, and a fourth pole piece 14 in a clockwise order. Every two pole pieces form an electrode pair, the second pole piece 12 and the fourth pole piece 14 form an X electrode pair, and the third pole piece 13 and the first pole piece 11 form a Y electrode pair. The first high-frequency power supply device comprises a first high-frequency power supply 31, a first transformer 33, a second high-frequency power supply 32 and a second transformer 34, wherein one pole of the output end of the first transformer 33 is connected with the fourth pole piece 14 through a fourth blocking capacitor 264, the other pole of the output end of the first transformer 33 is connected with the second pole piece 12 through a second blocking capacitor 262, the first high-frequency power supply 31 generates two high-frequency signals with pi phase difference through the first transformer 33, a dipole driving voltage U x is applied to the X electrode pair, and a dipole electric field in the X direction is generated in an analysis channel; one pole of the output end of the second transformer 34 is connected with the first pole piece 11 through the first blocking capacitor 261, the other pole of the output end of the second transformer 34 is connected with the third pole piece 13 through the third blocking capacitor 263, the second high-frequency power supply 32 generates two high-frequency signals with pi phase difference through the second transformer 34, a dipole driving voltage U y is applied to the Y electrode pair, and a dipole electric field in the Y direction is generated in the analysis channel. U x and U y have the same frequency and are phase-separated by ΔΦ, pi > |ΔΦ| > 0, which can generate a radial rotating electric field E in the analysis channel. Thus, ions are rotated by the radial rotating electric field force during the migration movement in the analysis channel. Because the charge center of the ion is not on the mass center, the ion rotates under the action of the electric field force, and the rotating direction is consistent with the rotating direction of the electric field. Most of chiral ions have a spiral structure, and since chiral enantiomer ions all rotate in the same direction, the difference of upwind and downwind occurs due to the gas collision resistance when the chiral enantiomer ions perform common axial electromigration relative to gas, mobility differences occur, and the time for reaching the ion detection device 6 is different for ion mobility spectrums, so that the separation effect is realized. A structural demonstration of a propeller with two different spiral directions can be made by using fig. 8, if the electromigration motion of the ions is to the left, equivalent to the situation that the propeller position is not moving and the air flow is to the right, and the ions with different chiralities have a first blade 81 and a second blade 82 with opposite spiral directions, when the chiral enantiomer molecules rotate around the migration axis in the same direction (the propellers are all rotated anticlockwise when seen from the left in the figure), the probability that the air molecules 80 in the air flow hit the first blade 81 (forward flow) is much smaller than the probability that the air molecules hit the second blade 82 (backward flow). That is, the resistance to the progress of the upper chiral ion is small, and the resistance to the progress of the lower chiral ion is large, thereby exhibiting different electric mobilities. When ΔΦ is greater than 0, the driving electric field in the analysis channel in the radial direction rotates clockwise around the axis of the analysis channel, and when ΔΦ is less than 0, the driving electric field in the analysis channel in the radial direction rotates counterclockwise around the axis of the analysis channel.
As shown in fig. 2, in this embodiment, the ion mobility analysis apparatus further includes a second high-frequency power supply device, which includes a radio-frequency power supply 22 and a third transformer 23, where the third transformer 23 is configured to generate radio-frequency outputs with opposite polarities, and the negative and positive output ends of the third transformer are respectively connected in series with the first and second transformer windings, and are respectively connected to the X electrode pair and the Y electrode pair of the electrode set 10 through a blocking capacitor, so that radio-frequency voltages with opposite polarities are applied to the two pairs of electrode pairs, and thus, in the analysis channel, a radio-frequency multipolar electric field mainly including a quadrupole field is superimposed on the basis of the rotating electric field. That is, in addition to the gradient dc voltage and the rotation driving voltage, the multi-row electrode group 10 is superimposed with the rf voltage that generates the quadrupole field that radially confines the ions, thereby preventing the ions from radially diffusing.
In general terms, in the present embodiment, the preferred target sequences of the phases of the 4 high-frequency signals generated by the first high-frequency power supply device are 0, pi/2, pi, 3 pi/2, respectively, and are output to the first pole piece 11, the second pole piece 12, the third pole piece 13, and the fourth pole piece 14 of the electrode group 10 in circumferential order, that is, the two dipole voltages U x and U y have a phase difference of |ΔΦ|= pi/2, thereby generating focusing and rotating electric fields at the same time at the four pole pieces of the electrode group 10, and playing roles of ion focusing and rotation driving.
Preferably, in this embodiment, the frequency of the output signal of the first high-frequency power supply device is adjustable, that is, the air pressure is optimized according to different samples. The output signal frequency of the first high-frequency power supply device is adjustable within the range of 100kHz to 100MHz, so that the ions in the analysis channel obtain proper rotation speed, the mobility difference of the enantiospecific ions in the electromigration process is ensured, and the effective separation is realized.
In the above embodiment, the voltage dividing resistor strings for applying the electromigration driving voltage to the electrodes of each row of the electrode groups 10 of the electrode array 1 have four groups, which requires that the resistance values are highly consistent, otherwise, the direct current potentials on the four pole pieces of each row of the electrode groups 10 have differences, so that the traction electric field is uneven. In this embodiment, another resistor string connection mode is provided, and the structure is shown in fig. 4, in which a first resistor 281 and a second resistor 282 are respectively connected to the first pole piece 11 and the third pole piece 13, and a third resistor 283 and a fourth resistor 284 are respectively connected to the second pole piece 12 and the fourth pole piece 14, and then are uniformly connected to a node of the voltage dividing resistor string, so that the voltages of the pole pieces of each row of electrode groups 10 can be ensured to be consistent.
In the foregoing embodiments, the dc power supply device employs the series arrangement of the voltage dividing resistors 25 to obtain the dc transition driving voltage, which is beneficial to reducing the number of dc power supplies. In other embodiments, the N node voltages of V 1 to V N may be supplied with variable dc voltages by a DA converter and output to the nodes via dc amplifiers for ease of regulation.
The resolution of the ion mobility spectrometry is limited by the length of the analysis channel, and in order to improve the resolution, the ion mobility analysis device according to another embodiment of the present invention further includes an airflow control device, so that the medium gas in the analysis channel flows directionally, thereby forming a trapping type ion mobility spectrometry device. As shown in fig. 5, from the ion source 5 side, the gas flow device forms a stable directional gas flow 41 in the analysis channel, and the direction of the directional gas flow 41 is opposite to the electromigration driving force 42 generated by the electrode array 1. That is, when positive ions are analyzed, the voltage V 1、V2、V3......VN is gradually increased, and an electric field is generated from right to left in the analysis channel. Ions of a certain mobility, the velocity of which is moved by the electrotransport drive 42, may just cancel out the gas flow velocity and thus accumulate somewhere in the analysis channel. Because the direct current power supply device can control N node voltages from V 1 to V N, an axial electrotransport electric field with positive gradient is realized in the trapped ion analysis channel, ions with different mobilities can stay at balanced electric field points corresponding to the analysis channel, and spatial separation is realized, so that the effective drift length of the ions is increased, and the resolution is improved.
In this embodiment, each row of electrode groups 10 of the electrode array 1 of the ion mobility analysis apparatus is divided into four pole pieces for generating a focused electric field and a rotating electric field. The first high-frequency power supply device also employs a first high-frequency power supply 31, a second high-frequency power supply 32, a first transformer 33, a second transformer 34 and a dc blocking capacitive coupling to apply voltages to the two pairs of electrode pairs, and superimposes a rotating voltage (dual-dipole stage) on the two-pole rf focusing voltage generated by the rf power supply 22 via the third transformer 23, thereby generating a rotating electric field rotating about the axis of migration. Ions of opposite chiral enantiomers, having opposite helical structures, have different collision probabilities when they all rotate in the same direction about an axis and collide with gas molecules in the axial gas flow, generate different collision resistances, and therefore exhibit different mobilities (see fig. 8), so as to be collected at different positions of the analysis channel, and realize spatial separation; when the gradient electric field is gradually reduced, ions in different chiral directions can be released at different times, so that time separation is realized.
In order to increase the effective drift length in a limited space, in other embodiments, the structure of the analysis channel may be optimized, for example, the analysis channel is configured to be curved; or the analysis channels are arranged into a plurality of channels, such as a first channel and a second channel, the outlet of the first channel is communicated with the inlet of the second channel through the side hole channel, and the above embodiments are beneficial to improving the resolution of the ion mobility spectrometry.
The electrode groups 10 of the electrode array 1 in the above embodiments all adopt a circumferential quarter-turn structure, the radial constraint focusing mainly uses a radio-frequency quadrupole field, and the rotating electric field needs to be connected in series through a transformer winding, so that the above-mentioned high-frequency voltage and the radio-frequency voltage are superimposed, and the circuit is relatively complex. As a simplified example, a radially constrained multipole radio frequency electric field may be applied to a portion of the electrode sets 10 in the electrode array 1, and a rotating electric field applied to another portion, the two electrode sets 10 being disposed in opposition.
The radial constraint multipole radio frequency electric field can be a quadrupole field (a circumferential quarter electrode plate), or can be a hexapole field, an octapole field and the like. In summary, the set of electrodes 10 generating the confining electric field comprises 2m pole pieces circumferentially arranged around the analysis channel, the second high frequency power supply means providing a pair of rf voltages of opposite polarity, one of the poles being output to the pole pieces having an odd number of circumferential numbers and the other of the poles being output to the pole pieces having an even number of circumferential numbers, so as to generate an rf multipole electric field in the analysis channel for radially confining ions, avoiding radial diffusion of ions.
In addition, the electrode group 10 of the generated rotating electric field is not necessarily equally divided, and may be equally divided or unequally divided in three, five, six or more in other embodiments. In summary, the electrode group 10 for generating a rotating electric field includes n pole pieces circumferentially arranged around the analysis channel, n is equal to or greater than 3, the first high-frequency power supply device generates n high-frequency signals having the same frequency and different phases, and the n high-frequency signals are sequentially output to the n pole pieces circumferentially arranged in phase order, so that voltages of different phases are applied to the divided pole pieces, thereby forming the rotating electric field. The power source for the rotary drive may be in the form of a radio frequency oscillator, may be driven by a high frequency amplifier, and may be driven by a digital switch. For example, in the embodiment shown in fig. 6, one electrode group 10 of the electrode array 1 is formed by three electrode plates, the three electrode plates are equidistantly and circumferentially arranged relative to the axis of the analysis channel, and the three electrode plates are respectively connected to the dc node voltage through a fifth resistor 285, a sixth resistor 286, and a seventh resistor 287, and are connected to the first switch driving circuit 271, the second switch driving circuit 272, and the third switch driving circuit 273 through a fifth blocking capacitor 265, a sixth blocking capacitor 266, and a seventh blocking capacitor 267. The three switch driving circuits perform switching operation according to a certain time sequence, the generated waveform phase shift sequences are 0, pi/3 and 2 pi/3, and three-phase digital waveforms as shown in V A、VB、VC below in FIG. 6 are output, so that radial three-phase rotating electric fields are generated in the ion transfer tube, and ions rotate in an analysis channel as the rotor of the three-phase motor.
The electrode assembly 10 in each of the above examples is shown as a ring, and in other embodiments the electrode assembly 10 may be square ring, or other shaped structures. The pole piece can be of a thin sheet structure, a thicker barrel shape or a laminated printed circuit board structure. The electrode group can be made of a piece of printed circuit board, or two or a plurality of printed circuit boards can be enclosed into an analysis channel, the analysis channel extends along the plane of the printed circuit board, and the metal surface on the circuit board forms the electrode plate in the electrode group. For example, in the embodiment shown in fig. 7, the electrode set 10 of the electrode array 1 is composed of four elongated metal pole pieces arranged in parallel, and the first pole piece 11, the second pole piece 12, the third pole piece 13 and the fourth pole piece 14 are arranged in circumferential order. The first pole piece 11 and the fourth pole piece 14 can be arranged on one printed circuit board, the second pole piece 12 and the third pole piece 13 can be arranged on the other printed circuit board, and the two circuit boards are placed face to form an analysis channel therebetween. The first high-frequency power supply 31, the second high-frequency power supply 32, the first transformer 33 and the second transformer 34 of the first high-frequency power supply device respectively output high-frequency signals with the same frequency and different phases to the four pole pieces through the blocking capacitors, so that a radial rotating electric field can be generated in an analysis channel, and the ion mobility of chiral molecules can be distinguished. In order to radially confine ions, the negative electrode of the radio frequency signal may be superimposed on the electrode pair formed by the second pole piece 12 and the fourth pole piece 14 through the first transformer 33, and the positive electrode of the radio frequency signal may be superimposed on the electrode pair formed by the first pole piece 11 and the third pole piece 14 through the second transformer 34.
The ion mobility analysis device provided in the above embodiment can make chiral enantiomer ions have mobility differences during the same-direction rotation and same-direction electromigration relative to a gas medium by applying a rotating electric field to the chiral enantiomer ions, so that spatial or temporal separation is generated, and the separation is detected by the ion detection device 6, thereby solving the problem that chiral molecules cannot be directly analyzed in the prior art. Preferably, the ion detection device 6 comprises a mass spectrometer, such as a conventional time-of-flight analyzer, or an electrostatic trap fourier transform mass spectrometer with ultra-high resolution capability. The ion mobility spectrometry and mass spectrometry are used in series, so that multidimensional ion analysis can be realized, and the analysis resolution is improved.
The working principle of the invention is based on the mobility difference that chiral ions do migration motion relative to gas along the axial direction while rotating along the same direction along the axial direction, so that time-space separation occurs in the axial direction, and the working principle of the invention is obviously different from that of the earlier linear ion trap plus rotating electric field to separate chiral ions in the radial direction.
Although the present disclosure is disclosed above, the scope of protection of the present disclosure is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the scope of the invention.
Claims (14)
1. An ion mobility analysis device, comprising
An ion source;
an analysis channel filled with a gas and extending along an ion electromigration direction;
an electrode array comprising a series of electrode sets arranged along the extension of the analysis channel;
A dc power supply device connected to each of the electrode groups for applying a gradient voltage across the electrode array to form an electrotransport drive dc electric field within the analysis channel;
The first high-frequency power supply device is connected with a plurality of rows of electrode groups in the electrode array, the electrode groups connected with the first high-frequency power supply device comprise n pole pieces which are circumferentially arranged around the analysis channel, n is more than or equal to 3, the first high-frequency power supply device is used for generating n high-frequency signals which have the same frequency and different phases, and n high-frequency signals are sequentially output to the n pole pieces which are circumferentially arranged according to the phase sequence so as to generate a high-frequency electric field for rotating ions.
2. The ion mobility analysis apparatus according to claim 1, wherein n=4, said first high-frequency power supply means generates 4 high-frequency signals having different phases, each of which has a phase sequence of 0, pi/2, pi, 3 pi/2, and outputs the signals to said 4 pole pieces of said electrode group arranged circumferentially in order of circumference.
3. The ion mobility analysis apparatus according to claim 1, wherein n=3, said first high-frequency power supply means generates 3 high-frequency signals having different phases, each of which has a phase sequence of 0, pi/3, 2 pi/3, and outputs to said pole pieces of said electrode group arranged in the circumferential direction in order of 3 phases.
4. The ion mobility analysis device of claim 1, wherein the output signal frequency of the first high frequency power supply device is between 100kHz and 100 MHz.
5. The ion mobility analysis apparatus according to claim 1, comprising a second high-frequency power supply device connected to a plurality of rows of the electrode groups in the electrode array, the electrode groups connected to the second high-frequency power supply device including 2m pole pieces circumferentially arranged around the analysis channel, the second high-frequency power supply device providing a pair of radio-frequency voltages of opposite polarities, one of which is output to the pole pieces of odd circumferential number and the other of which is output to the pole pieces of even circumferential number, generating a multipole field for radially confining ions.
6. The ion mobility analysis device of claim 5, wherein m = 2, the second high frequency power supply applies rf voltages of opposite polarity to the two pairs of pole pieces, creating an rf multipole field with a quadrupolar field.
7. The ion mobility analysis apparatus according to claim 6, wherein each row of the electrode groups includes four electrode pieces arranged circumferentially around the analysis channel, respectively a first electrode piece, a second electrode piece, a third electrode piece, and a fourth electrode piece, the first high-frequency power supply device generating four high-frequency signals having phases of 0, pi/2, pi, 3 pi/2, respectively, the first high-frequency power supply device being connected in series through a high-frequency transformer winding, and the high-frequency signals having phases of 0 and pi being superimposed on a radio-frequency voltage of one polarity generated by the second high-frequency power supply device, the first electrode piece and the third electrode piece being supplied, respectively; the first high-frequency power supply device is connected in series through a high-frequency transformer winding, a high-frequency signal with the phase of pi/2 and 3 pi/2 is superposed on the radio-frequency voltage with the other polarity generated by the second high-frequency power supply device, the radio-frequency voltage is respectively supplied to the second pole piece and the fourth pole piece, and a plurality of rows of electrode groups simultaneously generate a radial rotating electric field and a quadrupole field for restraining ions.
8. The ion mobility analysis apparatus according to any one of claims 1 to 7, comprising a gas flow control means for directing a gas in the analysis channel in a direction opposite to the electromigration driven dc electric field.
9. The ion mobility analysis device of any one of claims 1 to 7, wherein the analysis channel is linear or curved.
10. The ion mobility analysis apparatus according to any one of claims 1 to 7, wherein the analysis channel includes a first channel and a second channel, and an outlet of the first channel and an inlet of the second channel are communicated through a side hole channel.
11. The ion mobility analysis apparatus according to any one of claims 1 to 7, wherein the dc power supply apparatus includes a dc power supply and a voltage dividing resistor string connected to the dc power supply, and the dc power supply apparatus outputs a desired dc voltage to each electrode group in the electrode array by dividing the dc power supply by the voltage dividing resistor string.
12. The ion mobility analysis apparatus according to any one of claims 1 to 7, wherein the dc power supply apparatus includes a DA converter and a dc amplifier, the DA converter providing a variable dc voltage, the dc amplifier outputting a desired dc voltage to each of the electrode groups in the electrode array.
13. The ion mobility analysis device of any one of claims 1 to 7, further comprising an ion detection device disposed at an end of the analysis channel.
14. The ion mobility analysis device of claim 13, wherein the ion detection device comprises a mass spectrometer.
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| CN202410269226.5A CN118209620A (en) | 2024-03-11 | 2024-03-11 | Ion mobility analysis device |
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| CN202410269226.5A CN118209620A (en) | 2024-03-11 | 2024-03-11 | Ion mobility analysis device |
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