A segmented high-field asymmetric waveform ion mobility tube and applications

Abstract

The application discloses a segmented flat structure high-field asymmetric waveform ion mobility tube and application, which comprises a left-right two-end opening rectangular cross-section insulating cylinder body, the lower wall surface of the cylinder body is an insulating lower plate, and the upper wall surface of the cylinder body is an insulating upper plate; an ionization source is arranged between the insulating lower plate and the insulating upper plate and close to the left end port of the cylinder body, a pair of isolation ground electrodes and a pair of ion receiving electrodes are arranged between the insulating lower plate and the insulating upper plate and close to the right end port, two pairs or more than two pairs of opposite segmented electrode pairs are arranged between the ionization source and the pair of isolation ground electrodes and on the upper surface of the insulating lower plate and the lower surface of the insulating upper plate, the working gas pressure range is 10 pascal to 1 atmosphere, and the ion movement speed in the X-axis direction can be reduced, and the separation capacity is improved.

Description

TECHNICAL FIELD

[0001] The present application is a segmented high-field asymmetric waveform ion mobility tube, characterized by a segmented structure design, which uses a damping electric field opposite to the direction of carrier gas movement to reduce the movement speed of ions in the X-axis direction, increase the residence time, and thus improve the resolution capability. BACKGROUND

[0002] Ion mobility spectrometry is widely used for detecting chemical toxicants, drugs, stimulants, narcotics, and explosives due to its high sensitivity, fast analysis speed, portability, and other advantages. Among various types of ion mobility spectrometry, high-field asymmetric waveform ion mobility spectrometry technology has attracted increasing attention due to its high detection sensitivity, simple equipment, small size, portability, and low detection cost.

[0003] High-field asymmetric waveform ion mobility spectrometry is a material analysis and detection technology based on the continuous development of traditional ion mobility spectrometry technology, and was first publicly reported in 1993. It is based on the change in ion mobility in high-field (E / N>40Td, 1Td=10 - 17 Vcm2) and low-field (E / N<2Td) to achieve the detection of different substances. The principle of asymmetric field ion mobility spectrometry is as follows: the carrier gas makes the substance ions pass through the drift region perpendicular to the electric field direction, and the drift region applies an asymmetric field with positive and negative switching of radio frequency. During the entire radio frequency period, the time average of the voltage is zero. In this way, in the high-field and low-field sections, ions have a vertical displacement along the electric field with a mobility K, but if the mobility in the high-field and low-field is different, the ions will overall leave the original position in the vertical direction and produce a net displacement in a cycle. After a certain accumulation time, this displacement of the ions will make them hit the plate and be neutralized. In order to make the ions pass through the detection area smoothly, a direct current electric field can be superimposed on the original electric field. When the direct current electric field is appropriate, the net displacement of ions in the vertical direction is zero, and they can then pass through the detection channel smoothly and be detected. By scanning the above-mentioned direct current electric field, different ions can be detected.

[0004] High field asymmetric waveform ion mobility spectrometry can realize the separation of compounds with the same molecular weight and different structures, and can realize the separation and analysis of isomers in combination with mass spectrometry. In addition, in the field of protein analysis, high field asymmetric waveform ion mobility spectrometry can be used as a pre-separation front stage of mass spectrometry to eliminate low molecular weight compounds entering the mass spectrometer, greatly reduce background noise, improve signal-to-noise ratio, and increase sensitivity by 3 orders of magnitude. When the traditional high field asymmetric waveform ion mobility spectrometry is combined with mass spectrometry, only ions at a certain point can enter the mass spectrometer (Journal of the American Society for Mass Spectrometry 1999; 10: 492-501.), the ion utilization rate is low, and the sensitivity is poor. Then, in order to improve the ion utilization rate, a dome structure is proposed (Analytical Chemistry 2005; 77: 6381-6388.). In order to realize the change of mobility in high and low fields, a very high field strength is often required; this means that the voltage needs to be increased and the distance between the plates needs to be reduced. In order to realize miniaturization, the voltage that can be increased is limited. Therefore, the distance between the plates of the traditional high field asymmetric waveform ion mobility spectrometry is often set to be less than 1 mm. This means that the time in the separation zone needs to be reduced to avoid collisional quenching between ions and plates, thereby ensuring detection sensitivity. However, this results in low resolution.

[0005] The present application improves the separation ability of ions in the separation zone by designing a segmented flat plate structure and using the electric field force formed between the segmented electrodes in the opposite direction of ion motion to reduce the motion speed of ions. SUMMARY

[0006] The purpose of the present application is to solve the problem of low resolution of high field asymmetric waveform ion mobility tube and improve the separation ability of the instrument.

[0007] To achieve this purpose, the technical scheme adopted by the present application is:

[0008] A segmented flat plate structure high field asymmetric waveform ion mobility tube and application, including a left and right two end opening vertical to the X axis direction cross section is a rectangular insulating cylinder, the lower wall of the cylinder is an insulating lower plate, and the upper wall of the cylinder is an insulating upper plate, the direction from left to right is the X axis direction, and the direction from top to bottom is the Y axis direction.

[0009] The ionization source is arranged between the insulating lower plate and the insulating upper plate near the left port of the cylinder body, and the isolated ground electrode pair and the ion receiving electrode pair are arranged between the insulating lower plate and the insulating upper plate near the right port, the surfaces of the isolated ground electrode pair and the receiving pole surfaces of the ion receiving electrode pair are parallel to the X axis; the isolated ground electrode pair is located on the left side of the ion receiving electrode pair, and they are arranged at a distance from each other; the two electrodes in the isolated ground electrode pair and the ion receiving electrode pair are respectively arranged on the upper surface of the insulating lower plate and the lower surface of the insulating upper plate and are arranged opposite to each other;

[0010] Two or more pairs of segmented electrode pairs are arranged on the upper surface of the insulating lower plate and the lower surface of the insulating upper plate between the ionization source and the isolated ground electrode pair, including the first, second, …, and Nth electrode pairs; the two electrodes in the segmented electrode pair are respectively fixed on the lower surface of the insulating upper plate and the upper surface of the insulating lower plate and are arranged opposite to each other, and the two electrodes in the segmented electrode pair are respectively composed of two plate-shaped electrodes arranged vertically to the Y axis direction; the first, second, …, and Nth electrode pairs are sequentially and spaced arranged along the X axis direction, and N is an integer greater than or equal to 2; the Nth electrode pair and the isolated ground electrode pair are arranged at a distance and are spaced apart;

[0011] Different direct current voltages and the same high-field asymmetric radio frequency voltages are applied to the electrodes in the first, second, …, and Nth electrode pairs located inside the insulating upper plate, and direct current voltages are applied to the electrodes on the upper surface of the insulating lower plate.

[0012] The direction of the carrier gas flow is along the X axis direction, the axial direction electric field force on the ion in the segmented high-field asymmetric waveform ion migration tube is opposite to the direction of the carrier gas flow, and is smaller than the carrier force generated by the carrier gas; the residence time of the ion in the segmented high-field asymmetric waveform ion migration tube can be controlled by changing DC1, DC2, …, DCN, U1, U2, …, UN applied to the segmented electrode pairs; the voltage difference between DC1 and U1 is the same as the voltage difference between DC2 and U2 and the voltage difference between DCN and UN, and the amplitudes of U1, U2, …, and UN monotonically increase (or decrease).

[0013] The segmented electrode pairs are at least two pairs (preferably three pairs, i.e. N=3, the first, second, …, and Nth electrode pairs are the first, second, and third electrode pairs, and the distance between each pair of electrodes is 0.01 to 2 mm; the distance between the segmented electrode pairs is 0.1 to 5 mm.

[0014] The isolated ground electrode pair is connected to the ground; a direct current voltage of 1-10 V is applied to the ion receiving electrode.

[0015] The working gas pressure range is 10 pascal to 1 atmosphere;

[0016] The ion motion speed in the X axis direction can be reduced, and the separation capacity can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A segmented high-field asymmetric waveform ion mobility tube. A grid (1), a second focusing electrode pair (2), a second focusing electrode pair (3), an ion receiving electrode (4), an insulating cylinder (5);

[0018] Figure 2 Detection spectrum of DMMP DETAILED DESCRIPTION

[0019] A segmented high-field asymmetric waveform ion mobility tube with a flat plate structure and application, comprising a long rectangular insulating cylinder body with two open ends in the left and right perpendicular to the X-axis direction, the lower wall of the cylinder body is an insulating lower plate 2, and the upper wall of the cylinder body is an insulating upper plate 3, the direction from left to right is the X-axis direction, and the direction from top to bottom is the Y-axis direction;

[0020] An ionization source 1 is arranged between the insulating lower plate 2 and the insulating upper plate 3 near the left end of the cylinder body, and an isolation ground electrode pair 9, 9' and an ion receiving electrode pair 10, 10' are arranged between the insulating lower plate 2 and the insulating upper plate 3 near the right end; the surfaces of the isolation ground electrode pair 9, 9' and the receiving electrode surface of the ion receiving electrode pair 10, 10' are parallel to the X-axis; the isolation ground electrode pair 9, 9' is located on the left side of the ion receiving electrode pair 10, 10', and they are arranged at a distance from each other; two electrodes in the isolation ground electrode pair 9, 9' and the ion receiving electrode pair 10, 10' are respectively located on the upper surface of the insulating lower plate 2 and the lower surface of the insulating upper plate 3, and are oppositely arranged, both being flat plates;

[0021] Two or more pairs of opposite segmented electrode pairs are arranged on the upper surface of the insulating lower plate 2 and the lower surface of the insulating upper plate 3 between the ionization source 1 and the isolation ground electrode pair 9, 9', including first, second, third, fourth, and fifth electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8'; two electrodes in the segmented electrode pair are respectively fixed on the lower surface of the insulating upper plate 3 and the upper surface of the insulating lower plate 2, and are oppositely arranged, both being flat plates; two electrodes in the segmented electrode pair are respectively composed of two flat plate electrodes with surfaces perpendicular to the Y-axis direction; the first, second, third, fourth, and fifth electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8' are sequentially and spaced arranged along the X-axis direction; the fifth electrode pair and the isolation ground electrode pair 9, 9' are arranged at a distance;

[0022] Different direct currents DC1, DC2, DC3, DC4, DC5 and the same high-field asymmetric radio frequency voltage are applied to the electrodes 4, 5, 6, 7, 8 inside the insulating upper plate 3 in the first, second, third, fourth, and fifth electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8', and direct currents U1, U2, U3, U4, U5 are applied to the electrodes 4', 5', 6', 7', 8' on the upper surface of the insulating lower plate 2.

[0023] The direction of the carrier gas flow is along the X-axis, and the electric field force in the axial direction on the ions in the segmented high-field asymmetric waveform ion migration tube is opposite to the direction of the carrier gas flow and is smaller than the carrying force generated by the carrier gas; by changing DC1, DC2, DC3, DC4, DC5, U1, U2, U3, U4, and U5 applied to the segmented electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8', the residence time of the ions in the segmented high-field asymmetric waveform ion migration tube can be controlled; the voltage difference between DC1 and U1, the voltage difference between DC2 and U2, the voltage difference between DC3 and U3, the voltage difference between DC4 and U4, and the voltage difference between DC5 and U5 are the same, and the amplitudes of U1, U2, U3, U4, and U5 increase monotonically (or decrease).

[0024] The spacing between each pair of electrodes in the first, second, third, fourth and fifth electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8', the isolated ground electrode pair (9, 9') and the ion receiving electrodes (10, 10') is 0.5 mm; the spacing between the first, second, third, fourth and fifth electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8', the isolated ground electrode pair (9, 9') and the ion receiving electrodes (10, 10') is 0.5 mm.

[0025] The isolated ground electrode pair 9, 9' is connected to the ground;

[0026] A DC voltage of 10 V is applied to the ion receiving electrodes 10 and 10 ′.

[0027] Its operating pressure range is 1 atmosphere;

[0028] It can reduce the movement speed of ions in the X-axis direction and improve the separation ability.

[0029] Example:

[0030] An ionization source (1), an insulating lower plate (2), an insulating upper plate (3), first, second, third, fourth, and fifth separation electrode pairs (4, 4', 5, 5', 6, 6', 7, 7', 8, 8'), an isolated ground electrode pair (9, 9'), and ion receiving electrodes (10, 10').

[0031] DMMP enters the separation zone through vacuum ultraviolet ionization source 1, which is fixed on the first, second, third, fourth and fifth separation electrode pairs (4, 4', 5, 5', 6, 6', 7, 7', 8, 8') of the insulating lower plate (2) and the insulating upper plate (3). The mobility changes under the action of high and low fields in each separation electrode pair. Because the DC voltages applied to different separation electrode pairs are different, the damping force in the axial direction is reduced, the flight speed of ions in the axial direction is reduced, the residence time in the separation zone is increased, and the separation effect is improved. Finally, the ions enter the detection zone formed by the ion receiving electrodes (10, 10') through the region between the isolation electrode pairs (9, 9'). The typical spectrum of butanone sample under different voltage differences of the three-section electrode pair flat plate structure high-field asymmetric waveform ion mobility spectrometry is shown in Figure 2 The experimental conditions are as follows: RF is 1 MHz square wave asymmetric high voltage, high field is 1500 V, low field is 500 V, ratio of high field time to low field time is 0.25 microsecond: 0.75 microsecond. U1-U2, U2-U3, U3-U4, U4-U5 have the same δU, voltage difference between DC and U is 9 V. The distance between the electrode plates is 0.5 mm, and the distance between the segmented electrode pairs is 0.5 mm. Figure 2 The results of δU being 0.1 V and 0.2 V are given.

Claims

1. A segmented flat-plate structure high-field asymmetric waveform ion mobility tube, characterized in that: comprising a left and right two-end opening vertical to the X-axis direction rectangular cross-section insulating cylinder, the lower wall of the cylinder is an insulating lower plate (2), the upper wall of the cylinder is an insulating upper plate (3), the direction from left to right is the X-axis direction, and the direction from top to bottom is the Y-axis direction; an ionization source (1) is arranged between the insulating lower plate (2) and the insulating upper plate (3) near the left end port of the cylinder, an isolated ground electrode pair (9, 9') and an ion receiving electrode pair (10, 10') are arranged between the insulating lower plate (2) and the insulating upper plate (3) near the right end port, the surfaces of the isolated ground electrode pair (9, 9') and the receiving electrode surface of the ion receiving electrode pair (10, 10') are parallel to the X-axis; the isolated ground electrode pair (9, 9') is located on the left side of the ion receiving electrode pair (10, 10'), and they are arranged at a distance from each other; two electrodes in the isolated ground electrode pair (9, 9') and the ion receiving electrode pair (10, 10') are respectively arranged on the upper surface of the insulating lower plate (2) and the lower surface of the insulating upper plate (3) and are oppositely arranged; two pairs of above-mentioned segmented electrode pairs are arranged on the upper surface of the insulating lower plate (2) and the lower surface of the insulating upper plate (3) between the ionization source (1) and the isolated ground electrode pair (9, 9'), including first, second, …, N electrode pairs (4, 4', 5, 5' …… N, N'); two electrodes in the segmented electrode pairs are respectively arranged on the lower surface of the insulating upper plate (3) and the upper surface of the insulating lower plate (2) and are oppositely arranged, and two electrodes in the segmented electrode pairs are respectively composed of two flat plate electrodes arranged with surfaces perpendicular to the Y-axis direction; the first, second, …, N electrode pairs (4, 4', 5, 5' …… N, N') are sequentially and spaced arranged along the X-axis direction, and N is an integer greater than or equal to 2; the Nth electrode pair and the isolated ground electrode pair (9, 9') are arranged at a distance and are spaced apart; different direct current voltages DC1, DC2, …, DCN and the same high-field asymmetric radio frequency voltage are applied to the electrodes (4, 5, …, N) in the first, second, …, N electrode pairs (4, 4', 5, 5' …… N, N') located inside the insulating upper plate (3), and direct current voltages U1, U2, …, UN are applied to the electrodes (4', 5', …, N') on the upper surface of the insulating lower plate (2).

2. The segmented flat-plate structure high-field asymmetric waveform ion mobility tube according to claim 1, characterized in that: the direction of the carrier gas flow is along the X-axis direction, the axial direction electric field force experienced by the ions in the segmented high-field asymmetric waveform ion mobility tube is opposite to the direction of the carrier gas flow, and is smaller than the carrier force generated by the carrier gas; the residence time of the ions in the segmented high-field asymmetric waveform ion mobility tube can be controlled by changing DC1, DC2, …, DCN, U1, U2, …, UN applied to the segmented electrode pairs (4, 4', 5, 5' …… N, N'); the direct current voltage difference of each pair of electrodes in the segmented electrode pairs is the same, and the amplitudes of U1, U2, …, UN monotonically increase or decrease. ​ ​ ​ ​ ​ 3. The segmented flat-plate high-field asymmetric waveform ion mobility tube according to claim 1 or 2, wherein: The distance between the two electrodes in each pair of segmented electrodes is 0.01 to 2 mm, and the distance between the pairs of segmented electrodes is 0.1 to 5 mm.

4. The ion mobility tube according to claim 1, wherein: The pair of isolated electrodes (9, 9') is connected to the ground; A direct current voltage of 1-10 V is applied to the ion receiving electrodes (10, 10').

5. The segmented flat-plate high-field asymmetric waveform ion mobility tube according to claim 1, wherein: The working pressure range is 10 Pa to 1 atm.

6. The segmented-plate structure high-field asymmetric waveform ion mobility tube of claim 1, wherein: The ion movement speed in the X-axis direction is reduced, and the separation capacity is improved.

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