Sectional type high-field asymmetric waveform ion migration tube and application

Abstract

The invention relates to a segmented flat plate structure high-field asymmetric waveform ion migration tube and application, the segmented flat plate structure high-field asymmetric waveform ion migration tube comprises an insulating cylinder with a rectangular cross section, the lower wall surface of the cylinder is an insulating lower plate, and the upper wall surface of the cylinder is an insulating upper plate; an ionization source is arranged between the insulating lower plate and the insulating upper plate and close to a left port of the cylinder, and an isolation ground electrode pair and an ion receiving electrode pair are arranged between the insulating lower plate and the insulating upper plate and close to a right port; between the ionization source and the isolated ground electrode pair, two or more pairs of opposite sectional electrode pairs are arranged on the upper surface of the lower insulating plate and the lower surface of the upper insulating plate, and the working air pressure range is 10 Pascals to 1 atmospheric pressure; the moving speed of ions in the X-axis direction can be reduced, and the separation capacity is improved.

Description

Technical Field

[0001] The present invention is a segmented high-field asymmetric waveform ion migration tube, which is characterized by a segmented structural design, using a damping electric field opposite to the carrier gas movement direction to reduce the movement speed of ions in the X-axis direction and increase the residence time, thereby improving the resolution. Background Art

[0002] Ion mobility spectrometry is widely used in the detection of chemical agents, drugs, stimulants, anesthetics and explosives due to its advantages of high sensitivity, fast analysis speed and portability. Among the various types of ion mobility spectrometry, high-field asymmetric waveform ion mobility spectrometry technology has the advantages of high detection sensitivity, simple equipment, small size, easy to carry and low detection cost, and is increasingly gaining attention.

[0003] High-field asymmetric waveform ion mobility spectrometry is a material analysis and detection technology that has been continuously developed based on traditional ion mobility spectrometry technology. It was first publicly reported in 1993. It is based on the ion in high field (E / N>40Td, 1Td=10 - 17 Vcm2) and low field (E / N<2Td) to realize the detection of different substances. The principle of asymmetric field ion mobility spectrometry is as follows: the carrier gas is used to make the material ions pass through the drift region perpendicular to the direction of the electric field, and the drift region is applied with an asymmetric field with positive and negative switching of radio frequency. During the entire radio frequency cycle, the time average value of the voltage is zero. In this way, in the high and low field sections, the ions have a vertical displacement along the electric field with a mobility K. However, if the mobility under the high field and the low field is different, the ions will generally leave their original positions in the direction perpendicular to the direction within a cycle, resulting in a net displacement. After a certain period of accumulation, this displacement of the ions will cause them to hit the plate and be neutralized. In order to make this ion pass through the detection area smoothly, a DC electric field can be superimposed on the original electric field. When the DC electric field applied is appropriate, the net displacement of the ions in the vertical direction is zero, and then they can be smoothly detected through the detection channel. By scanning the above-mentioned DC electric field, different ions can be detected.

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

[0005] The present invention adopts a segmented structure design of a flat plate structure, utilizes the electric field force formed between segmented electrodes in the opposite direction of ion movement to reduce the movement speed of ions, and improves the separation ability of ions in the separation area. Summary of the invention

[0006] The invention aims to solve the problem of low resolution of a high-field asymmetric waveform ion migration tube and improve the separation capability of the instrument.

[0007] To achieve this purpose, the technical solution adopted by the present invention is:

[0008] A segmented flat plate structure high-field asymmetric waveform ion migration tube and its application, comprising a rectangular insulating cylinder with two openings at the left and right ends perpendicular to the X-axis direction, the lower wall of the cylinder is an insulating lower plate, 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] An ionization source is provided between the insulating lower plate and the insulating upper plate near the left port of the cylinder, and an isolated ground electrode pair and an ion receiving electrode pair are provided between the insulating lower plate and the insulating upper plate near the right port, and the surfaces of the isolated ground electrode pair and the receiving electrode 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 spaced apart from each other; two electrodes in the isolated ground electrode pair and the ion receiving electrode pair are respectively located 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 between the ionization source and the isolated ground electrode pair, on the upper surface of the insulating lower plate and the lower surface of the insulating upper plate, including the first, second ... Nth electrode pairs; the two electrodes in the segmented electrode pair are respectively fixed to 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 flat-plate electrodes with surfaces perpendicular to the Y-axis direction; the first, second ... Nth electrode pairs are arranged in sequence along the X-axis direction, and N is an integer greater than or equal to 2; a gap is left between the Nth electrode pair and the isolated ground electrode pair, and the interval is arranged;

[0011] Different DC voltages and the same high-field asymmetric radio frequency voltage are applied to the electrodes located on the inner side of the insulating upper plate in the first, second ... Nth electrode pairs, and a DC voltage is applied to the electrodes located on the upper surface of the insulating lower plate.

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

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

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

[0015] Its operating pressure range is 10 Pascals to 1 atmosphere;

[0016] It can reduce the movement speed of ions in the X-axis direction and improve the separation ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The invention is a segmented high-field asymmetric waveform ion migration tube. The invention comprises a grid (1), a second focusing electrode pair (2), a second focusing electrode pair (3), an ion receiving electrode (4), and an insulating tube (5);

[0018] Figure 2 Detection spectrum of DMMP DETAILED DESCRIPTION

[0019] A segmented flat plate structure high-field asymmetric waveform ion migration tube and its application, comprising a rectangular insulating cylinder with two openings at the left and right ends perpendicular to the X-axis direction, 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;

[0020] An ion source 1 is provided between the insulating lower plate 2 and the insulating upper plate 3 near the left port of the cylinder, and an isolated ground electrode pair 9, 9' and an ion receiving electrode pair 10, 10' are provided between the insulating lower plate 2 and the insulating upper plate 3 near the right port. The surfaces of the isolated ground electrode pair 9, 9' and the receiving electrode surfaces of the ion receiving electrode pair 10, 10' are parallel to the X-axis; the isolated ground electrode pair 9, 9' are located on the left side of the ion receiving electrode pair 10, 10', and they are spaced apart from each other; the two electrodes of the isolated 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 arranged oppositely, and are both in the shape of flat plates;

[0021] Two or more pairs of segmented electrode pairs are arranged between the ionization source 1 and the isolated ground electrode pair 9, 9', on the upper surface of the insulating lower plate 2 and the lower surface of the insulating upper plate 3, including the first, second, third, fourth, and fifth electrode pairs 4, 4', 5, 5', 6, 6', 7, 7', 8, 8'; the two electrodes in the segmented electrode pair are respectively fixed to the lower surface of the insulating upper plate 3 and the upper surface of the insulating lower plate 2, and are arranged oppositely, and are both flat-plate-shaped, and the two electrodes in the segmented electrode pair are respectively composed of two flat-plate electrodes arranged 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 arranged in sequence along the X-axis direction; a gap is left between the fifth electrode pair and the isolated ground electrode pair 9, 9', and the interval is arranged;

[0022] Different DC voltages DC1, DC2, DC3, DC4, DC5 and the same high-field asymmetric RF voltage are applied to the electrodes 4, 5, 6, 7, 8 located on the inner side of 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 DC voltages U1, U2, U3, U4, U5 are applied to the electrodes 4', 5', 6', 7', 8' located on the upper surface of the insulating lower plate 2.

[0023] The direction of carrier gas flow is along the X-axis direction, and the electric field force in the axial direction on ions in the segmented high-field asymmetric waveform ion migration tube is opposite to the direction of carrier gas flow and is smaller than the carrying force generated by the carrier gas; the residence time of ions in the segmented high-field asymmetric waveform ion migration tube can be controlled 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 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 (or decrease) monotonically.

[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 working 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 formed by the first, second, third, fourth and fifth separation electrode pairs (4, 4', 5, 5', 6, 6', 7, 7', 8, 8') fixed on the insulating lower plate (2) and the insulating upper plate (3) through the vacuum ultraviolet ionization source 1. The mobility changes under the action of high and low fields in each separation electrode pair. Due to the different DC voltages applied to different separation electrode pairs, the damping force in the axial direction is formed to reduce the flight speed of the ions on the axis, thereby increasing the residence time in the separation zone and improving the separation effect. Finally, the ions pass through the area between the isolation electrode pairs (9, 9') and enter the detection zone formed by the ion receiving electrodes (10, 10'). The typical spectrum of the butanone sample with a high-field asymmetric waveform ion migration spectrum of a flat plate structure with three-segment electrode pairs under different segmented voltage differences is shown in the figure below. Figure 2 As shown. Experimental conditions: RF is 1MHz square wave asymmetric high voltage, high field is 1500V, low field is 500V, high field time to low field time ratio is 0.25 microseconds: 0.75 microseconds. U1-U2, U2-U3, U3-U4, U4-U5 have the same δU, and the voltage difference between DC and U is 9V. The distance between the plates is 0.5mm, and the distance between the segmented electrode pairs is 0.5mm. Figure 2 The results for δU of 0.1V and 0.2V are given.

Claims

1. A segmented flat plate structure high field asymmetric waveform ion transfer tube and its application, characterized in that: It comprises an insulating cylinder with two openings at the left and right ends perpendicular to the X-axis direction and a rectangular cross-section, 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 provided between the insulating lower plate (2) and the insulating upper plate (3) near the left end of the cylinder, and an isolated ground electrode pair (9, 9') and an ion receiving electrode pair (10, 10') are provided between the insulating lower plate (2) and the insulating upper plate (3) near the right end. The surfaces of the isolated ground electrode pair (9, 9') and the receiving electrode surfaces 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 intervals from each other; two electrodes of the isolated 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 arranged opposite to each other; Two or more pairs of segmented electrode pairs are arranged between the ionization source (1) and the isolated ground electrode pair (9, 9'), on the upper surface of the insulating lower plate (2) and the lower surface of the insulating upper plate (3), including first, second ... Nth electrode pairs (4, 4', 5, 5' ... N, N'); two electrodes in the segmented electrode pairs are respectively fixed to the lower surface of the insulating upper plate (3) and the upper surface of the insulating lower plate (2), and are arranged opposite to each other, and the two electrodes in the segmented electrode pairs are respectively composed of two flat plate electrodes whose surfaces are arranged perpendicular to the Y-axis direction; the first, second ... Nth electrode pairs (4, 4', 5, 5' ... N, N') are arranged in sequence along the X-axis direction, and N is an integer greater than or equal to 2; a gap is left between the Nth electrode pair and the isolated ground electrode pair (9, 9'), and the interval is arranged; Different direct current voltages (DC1, DC2 ... DCN) and the same high-field asymmetric radio frequency voltage are applied to the electrodes (4, 5 ... N) located on the inner side of the insulating upper plate (3) in the first, second ... Nth electrode pairs (4, 4', 5, 5' ... N, N'), and direct current voltages (U1, U2 ... UN) are applied to the electrodes (4', 5' ... N') located on the upper surface of the insulating lower plate (2).

2. The segmented flat plate structure high field asymmetric waveform ion transfer tube according to claim 1, characterized in that: The carrier gas flow direction is along the X-axis direction, 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 carrier gas flow direction 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 migration tube can be adjusted by changing DC1, DC2...DCN, U1, U2...UN applied to the segmented electrode pair (4, 4', 5, 5'...N, N'); the voltage difference between DC1 and U1 is the same as the voltage difference between DC2 and U2 and the voltage difference between DCN...UN, and the amplitudes of U1, U2...UN increase (or decrease) monotonically.

3. The segmented flat plate structure high field asymmetric waveform ion transfer tube according to claim 1 or 2, characterized in that: There are at least two pairs of segmented electrode pairs (preferably 3 pairs, i.e. N=3, the first, second ... Nth electrode pairs (4, 4', 5, 5', 6, 6') are the first, second, third electrode pairs (4, 4', 5, 5', 6, 6')), and the spacing between each pair of electrodes is 0.01 to 2 mm; the spacing between the segmented separation electrode pairs is 0.1 to 5 mm.

4. The ion transfer tube according to claim 1, characterized in that: The isolated ground electrode pair (9, 9') is connected to the ground; A DC voltage of 1-10 V is applied to the ion receiving electrodes (10, 10').

5. The segmented flat plate structure high field asymmetric waveform ion transfer tube according to claim 1, characterized in that: Its operating pressure range is 10 Pascals to 1 atmosphere; 6. The segmented flat plate structure high field asymmetric waveform ion transfer tube according to claim 1, characterized in that: It can reduce the movement speed of ions in the X-axis direction and improve the separation ability.

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