CN116978770A - Polarity switching ion migration tube - Google Patents

Abstract

The invention discloses a polarity switching ion migration tube. The ion transfer tube adopts a double parallel gate ion gate, and a first gate electrode and a second gate electrode of the ion gate are respectively connected with the output end of a first isolated high-voltage pulse power supply and the output end of a second isolated high-voltage pulse power supply; when the ion migration tube works, the output potential of the high-voltage power supply supplied by the migration tube is rapidly switched between positive high voltage and negative high voltage; the addition of the positive ion analysis period and the negative ion analysis period constitutes a complete time period for the operation of the polarity switching ion transfer tube.

Description

Polarity switching ion migration tube

Technical Field

The invention relates to an ion transfer tube of a core component of an ion transfer spectrometer, in particular to a polarity switching ion transfer tube using double parallel gate ion gates.

Background

The bipolar ion transfer tube can realize simultaneous or quasi-simultaneous detection of positive and negative ions in the same ion transfer tube, thereby providing multidimensional ion information. There are two implementations of bipolar ion transfer tubes: one is to realize the simultaneous detection of positive and negative ions by simultaneously arranging a positive ion detection electrode and a negative ion detection electrode in a single migration tube, and the migration electric field applied in the whole migration tube is constant, for example, the application of an authorized patent such as Peng Hua (CN 101728208); the other is that only a single ion detection electrode is arranged in the migration tube, and the accurate and simultaneous detection of positive and negative ions is realized by periodically and rapidly switching the direction of a migration electric field in the migration tube, which is also called a polarity switching ion migration tube, for example, a Stroosnyder grant patent application (US 5587581) and a Jenkins grant patent application (US 5200614).

For a polarity switching ion transfer tube, the configuration of the ion gate affects its structural design and performance. Jenkins (US 5200614) and Zaleski (US 9709530) respectively disclose a polarity switching ion transfer tube employing three parallel gate ion gates. Wherein the ion source is required to be placed between two grids of the three parallel grid ion gates. Such ion gate structures are poorly compatible with long ionization range ion sources. Wang Weiguo et al (CN 201911157574.9) also disclose a three parallel gate ion gate for a polarity switching ion transfer tube, which can realize gate injection of ions in positive and negative polarity modes by controlling the voltage variation of the intermediate gate. However, these disclosed tri-gate ion gates generally suffer from ion implantation discrimination and ion permeation inefficiency.

In addition, in the polarity switching ion transfer tube disclosed at present, a mode of injecting ion groups into a transfer area is generally adopted to realize ion separation and analysis. In the ion transfer tube, residual charges on the inner wall of the transfer region in the previous polarity analysis period are difficult to be quickly neutralized, so that the transfer efficiency and transfer time of the ion groups in the transfer region in the next polarity analysis period are influenced, further the detection sensitivity is reduced, the ion spectrum peak transfer time is shifted, and the accurate identification and sensitive detection of the target are influenced.

Disclosure of Invention

The invention discloses a polarity switching ion migration tube adopting double parallel gate ion gates. The polarity switching ion migration tube is enabled to work in an opposite phase ion detection mode in a positive ion analysis period and a negative ion analysis period by regulating and controlling the electric potential of the two grid electrodes of the ion gate, namely, accurate identification and high-sensitivity quantitative analysis of different ions with mobility K are realized by detecting the migration characteristics of ion holes in ion base flow. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the ion transfer tube is composed of an ion source, an ionization region, an ion gate, a transfer region and an ion receiving electrode which are coaxially arranged in sequence from left to right;

the ionization region and the migration region are respectively cylindrical hollow cavities formed by alternately and coaxially overlapping annular electrodes and annular insulators from left to right in sequence; the ion gate is formed by sequentially and coaxially overlapping a circular first gate electrode, a circular insulator and a circular second gate electrode, and circular metal grids capable of penetrating ions are respectively arranged in middle through holes of the first gate electrode and the second gate electrode;

the ion gate is positioned between the ionization region at the left side and the migration region at the right side, the ionization region is in airtight connection with a first gate electrode of the ion gate through a circular ring-shaped insulator, the migration region is in airtight connection with a second gate electrode of the ion gate through the circular ring-shaped insulator, an ion source positioned at the left side of the ionization region is in airtight connection with the ionization region through the circular ring-shaped insulator, an ion receiving electrode positioned at the right side of the migration region is in airtight connection with the migration region through the circular ring-shaped insulator, a floating gas inlet is arranged on the ion receiving electrode, and a sample gas inlet and a gas outlet are arranged on the ion source;

The voltage dividing resistor chain is formed by connecting more than 5 equivalent resistors in series in sequence, the connection points between the two ends of the voltage dividing resistor chain and the adjacent resistors are electrical connection points, the reference voltage input end of the ion source, the annular electrode of the ionization region, the reference voltage input end of the first isolated high-voltage pulse power supply, the reference voltage input end of the second isolated high-voltage pulse power supply, the annular electrode of the migration region and the ion receiving electrode are connected with the electrical connection points of the voltage dividing resistor chain in a one-to-one correspondence manner in the direction from the ion source to the ion receiving electrode, the electrical connection points of the voltage dividing resistor chain, which are close to one end of the ion source, are connected with the high-voltage output terminal of the high-voltage power supply and the ground;

the high-voltage pulse output end of the first isolated high-voltage pulse power supply is connected with the first gate electrode, the high-voltage pulse output end of the second isolated high-voltage pulse power supply is connected with the second gate electrode, the first isolated high-voltage pulse power supply and the second isolated high-voltage pulse power supply work cooperatively to control the electric potential of the first gate electrode and the second gate electrode, and ion holes accompanied with continuous ion flow migration are formed in the ion migration tube to realize separation and detection of ions with different ion mobilities K;

The method comprises the steps that in a first preset time interval t1, a second preset time interval t2 and a third preset time interval t3, a high-voltage power supply outputs positive potential, a first isolated high-voltage pulse power supply and a second isolated high-voltage pulse power supply modulate the potentials on a first gate electrode and a second gate electrode simultaneously according to the sequence of the first preset time interval t1, the second preset time interval t2 and the third preset time interval t3, the ion gate is controlled to be sequentially switched between an opening state, a closing state and an opening state, ion holes are formed in continuous positive ion flow in an ion migration tube, and the ion holes are injected into a migration zone to conduct reverse ion separation and detection, so that a positive ion migration spectrogram is obtained;

the method comprises the steps that in a fourth preset time interval t4, a fifth preset time interval t5 and a sixth preset time interval t6, a high-voltage power supply outputs negative potential, a first isolated high-voltage pulse power supply and a second isolated high-voltage pulse power supply modulate the potentials on a first gate electrode and a second gate electrode simultaneously according to the sequence of the fourth preset time interval t4, the fifth preset time interval t5 and the sixth preset time interval t6, an ion gate is controlled to be sequentially switched among three states of opening, closing and opening, ion holes are formed in continuous negative ion flows in an ion migration tube, and the negative ion holes are injected into a migration zone to conduct reverse ion separation and detection, so that a negative ion migration spectrogram is obtained;

In a first preset time interval t1, outputting positive potential V < 1+ > by the high-voltage power supply, outputting positive potential V < 2+ > by the first isolated high-voltage pulse power supply, outputting positive potential V < 3+ > by the second isolated high-voltage pulse power supply, forming a direct current electric field along the direction from the ion source to the ion receiving electrode in the ionization region and the migration region, forming a direct current electric field along the direction from the ion source to the ion receiving electrode between the first gate electrode and the second gate electrode, migrating positive ions generated by the ion source along the direction from the ion source to the ion receiving electrode, filling the interior of the ion migration tube, forming continuous positive ion flow, and enabling the inner wall of the migration region to reach positive charge balance rapidly;

in a second preset time interval t2, the positive potential V < 1+ > is output by the high-voltage power supply, the positive potential V < 4+ > is reduced from V < 2+ > output by the first isolated high-voltage pulse power supply, the positive potential V < 3+ > is output by the second isolated high-voltage pulse power supply, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed in the migration area, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed between the first gate electrode and the second gate electrode, positive ions between the first gate electrode and the second gate electrode migrate towards the first gate electrode and annihilate on the first gate electrode, and ion holes without ions exist are formed between the first gate electrode and the second gate electrode;

In a third preset time interval t3, the high-voltage power supply outputs positive potential V1+, the first isolated high-voltage pulse power supply outputs positive potential V3+ which is increased from V4+ to V2+, the second isolated high-voltage pulse power supply outputs positive potential V3+, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed in the migration area, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed between the first gate electrode and the second gate electrode, and ion holes between the first gate electrode and the second gate electrode enter the migration area along with positive ion flow and migrate towards the ion receiving electrode and are finally detected by the ion receiving electrode to form a positive ion migration spectrogram;

in a fourth preset time interval t4, the high-voltage power supply outputs a negative potential V1-, the first isolated high-voltage pulse power supply outputs a negative potential V2-, the second isolated high-voltage pulse power supply outputs a negative potential V3-, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed in the ionization region and the migration region, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed between the first gate electrode and the second gate electrode, negative ions generated by the ion source migrate along the direction from the ion source to the ion receiving electrode and are filled in the ion migration tube, continuous negative ion flow is formed, and the inner wall of the migration region rapidly reaches negative charge balance;

In a fifth preset time interval t5, the high-voltage power supply outputs a negative potential V1-, the first isolated high-voltage pulse power supply outputs a negative potential V2-, the second isolated high-voltage pulse power supply outputs a negative potential which is reduced from V3-to V4-, a direct current electric field from an ion receiving electrode to an ion source is formed in the migration zone, a direct current electric field from the ion source to the ion receiving electrode is formed between the first gate electrode and the second gate electrode, negative ions between the first gate electrode and the second gate electrode migrate towards the first gate electrode and annihilate on the first gate electrode, and ion holes without ions exist between the first gate electrode and the second gate electrode;

in a sixth preset time interval t6, the high-voltage power supply outputs a negative potential V1-, the first isolated high-voltage pulse power supply outputs a negative potential V2-, the second isolated high-voltage pulse power supply outputs a negative potential which is increased from V4 to V3-, a direct current electric field from the ion receiving electrode to the ion source is formed in the migration zone, a direct current electric field from the ion receiving electrode to the ion source is formed between the first gate electrode and the second gate electrode, ion holes between the first gate electrode and the second gate electrode enter the migration zone along with the negative ion flow and migrate towards the ion receiving electrode, and finally the ion holes are detected by the ion receiving electrode to form a negative ion migration spectrogram;

Or in a first preset time interval t1, outputting positive potential V < 1+ > by the high-voltage power supply, outputting positive potential V < 2+ > by the first isolated high-voltage pulse power supply, outputting positive potential V < 3+ > by the second isolated high-voltage pulse power supply, forming a direct current electric field along the direction from the ion source to the ion receiving electrode in the ionization region and the migration region, forming a direct current electric field along the direction from the ion source to the ion receiving electrode between the first gate electrode and the second gate electrode, and enabling positive ions generated by the ion source to migrate along the direction from the ion source to the ion receiving electrode and fully filling the interior of the ion migration tube to form continuous positive ion flow, wherein the inner wall of the migration region rapidly reaches positive charge balance;

in a second preset time interval t2, the high-voltage power supply outputs positive potential V1+, the first isolated high-voltage pulse power supply outputs positive potential V2+, the second isolated high-voltage pulse power supply outputs positive potential to be raised from V3+ to V5+, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed in the migration area, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed between the first gate electrode and the second gate electrode, positive ions between the first gate electrode and the second gate electrode migrate towards the first gate electrode and annihilate on the first gate electrode, and ion holes without ions are formed between the first gate electrode and the second gate electrode;

In a third preset time interval t3, the high-voltage power supply outputs positive potential V1+, the first isolated high-voltage pulse power supply outputs positive potential V2+, the positive potential output by the second isolated high-voltage pulse power supply is reduced from V5+ to V3+, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed in the migration area, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed between the first gate electrode and the second gate electrode, and ion holes between the first gate electrode and the second gate electrode enter the migration area along with positive ion flow and migrate towards the ion receiving electrode and are finally detected by the ion receiving electrode, so that a positive ion migration spectrogram is formed;

in a fourth preset time interval t4, the high-voltage power supply outputs a negative potential V1-, the first isolated high-voltage pulse power supply outputs a negative potential V2-, the second isolated high-voltage pulse power supply outputs a negative potential V3-, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed in the ionization region and the migration region, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed between the first gate electrode and the second gate electrode, negative ions generated by the ion source migrate along the direction from the ion source to the ion receiving electrode and are filled in the ion migration tube to form continuous negative ion flow, and the inner wall of the migration region (4) rapidly reaches negative charge balance;

In a fifth preset time interval t5, the high-voltage power supply outputs a negative potential V1-, the first isolated high-voltage pulse power supply outputs a negative potential V3-, the second isolated high-voltage pulse power supply outputs a negative potential V3-, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed in the ionization region and the migration region, a direct current electric field along the direction from the ion source to the ion receiving electrode is formed between the first gate electrode and the second gate electrode, negative ions between the first gate electrode and the second gate electrode migrate towards the first gate electrode and annihilate on the first gate electrode, and ion holes without ions are formed between the first gate electrode and the second gate electrode;

in a sixth preset time interval t6, the high-voltage power supply outputs a negative potential V1-, the first isolated high-voltage pulse power supply outputs a negative potential V3-, the second isolated high-voltage pulse power supply outputs a negative potential V3-, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed in the ionization region and the migration region, a direct current electric field along the direction from the ion receiving electrode to the ion source is formed between the first gate electrode and the second gate electrode, ion holes between the first gate electrode and the second gate electrode enter the migration region along with the negative ion flow and migrate towards the ion receiving electrode, and finally are detected by the ion receiving electrode, so that a negative ion migration spectrogram is formed;

The potentials V1-, V4-, V2-, V3-, and V5-are of negative polarity, i.e., the values of the potentials V1-, V4-, V2-, V3-, and V5-are less than 0, the potentials V4+, V3+, V2+, V5+ and V1+ are of positive polarity, i.e., the values of V4+, V3+, V2+, V5+ and V1+ are greater than 0, the potentials V1-, V4-, V2-, V3-, V5-, 0, V4+, V3+, V2+, V5+ and V1+ are sequentially increased;

the first preset time interval t1 is 1-3 ms, the second preset time interval t2 is 0.01-0.2 ms, the third preset time interval t3 is 3-25 ms, the fourth preset time interval t4 is 1-3 ms, the fifth preset time interval t5 is 0.01-0.2 ms, and the sixth preset time interval t6 is 3-25 ms;

the positive ion analysis period of the polarity switching ion transfer tube is formed by the summation of a first preset time interval t1, a second preset time interval t2 and a third preset time interval t3, the negative ion analysis period of the polarity switching ion transfer tube is formed by the summation of a fourth preset time interval t4, a fifth preset time interval t5 and a sixth preset time interval t6, and a complete time period of the polarity switching ion transfer tube is formed by the summation of the first preset time interval t1, the second preset time interval t2, the third preset time interval t3, the fourth preset time interval t4, the fifth preset time interval t5 and the sixth preset time interval t 6;

When the ion transfer tube works, the electric potentials output by the high-voltage power supply, the first isolated high-voltage pulse power supply and the second isolated high-voltage pulse power supply are periodically and circularly regulated according to the time period;

one path of bleaching gas enters the ion migration tube through the bleaching gas inlet (12), flows into the ionization region (2) through the ion gate (3), is mixed with one path of sample gas entering the ionization region (2) through the sample gas inlet (13), then flows out of the ion migration tube through the gas outlet (14), and is clean air which is sequentially filtered through activated carbon and a 13X molecular sieve, and the sample gas is clean air containing target analytes with specific concentration.

The invention discloses a polarity switching ion migration tube which adopts a double parallel gate ion gate, wherein a first gate electrode and a second gate electrode of the ion gate are respectively connected with an output end of a first isolated high-voltage pulse power supply and an output end of a second isolated high-voltage pulse power supply; when the ion migration tube works, the output potential of the high-voltage power supply supplied by the migration tube is rapidly switched between positive high voltage and negative high voltage; when the output of the high-voltage power supply is switched from negative high voltage to positive high voltage, the ion migration tube enters a positive ion analysis period, the gate electrode potential of the ion gate is modulated by the first isolation high-voltage pulse power supply and the second isolation high-voltage pulse together, ion holes are formed in continuous positive ion flow, and the ion holes are injected into a migration zone for reverse ion separation and detection, so that a positive ion migration spectrogram is obtained; when the output of the high-voltage power supply is switched from positive high voltage to negative high voltage, the ion migration tube enters a negative ion analysis period, the gate electrode potential of the ion gate is modulated by the first isolation high-voltage pulse power supply and the second isolation high-voltage pulse together, ion holes are formed in continuous negative ion flow and are injected into a migration zone for reverse ion separation and detection, and a negative ion migration spectrogram is obtained; the addition of the positive ion analysis period and the negative ion analysis period constitutes a complete time period for the operation of the polarity switching ion transfer tube.

The invention has the advantages that:

the polarity switching ion migration tube disclosed by the invention adopts the double parallel grid ion gates, so that the use of grids is reduced, and the improvement of ion transmission efficiency is facilitated. The polarity switching ion migration tube works in an opposite-phase ion detection mode, on one hand, ions with different mobilities K can be guaranteed to form approximately consistent hole widths, detection sensitivity difference caused by mobility discrimination is eliminated, and the edges of ion holes formed based on double parallel gate ion gates are smoother, so that high resolution capability is better obtained; on the other hand, the continuous ion flow can quickly neutralize residual charges on the inner wall of the migration zone in the previous analysis period and reach new charge deposition balance, so that the influence of charge deposition imbalance on detection sensitivity and ion migration time is eliminated.

The invention is described in further detail below with reference to the accompanying drawings:

drawings

Fig. 1 is a schematic cross-sectional view of a polarity switching ion transfer tube according to the present invention. Wherein: 1. an ion source; 2. an ionization region; 3. an ion gate; 31. a first gate electrode; 32. a second gate electrode; 4. a migration zone; 5. an ion receiving electrode; 6. a ring electrode; 7. a ring-shaped insulator; 8. a resistor chain; 9. a high voltage power supply; 10. a first isolated high voltage pulse power supply; 11. a second isolated high voltage pulse power supply; 12. a bleaching gas inlet; 13. a sample gas inlet; 14. and an air outlet.

Fig. 2 is a waveform of the output potential of the high voltage power supply 9 in the ion transfer tube according to the present invention. Wherein the output potential of the high voltage power supply 9 varies between v1+ and V1-; in the period of adding t1, t2 and t3, the high-voltage power supply 9 outputs a potential V1+, and the ion transfer tube works in the positive ion analysis period; in the period where t4, t5 and t6 are added up, the high-voltage power supply 9 outputs the potential V1-, and the ion transfer tube operates in the negative ion analysis period.

Fig. 3 is a waveform of the potential of a gate electrode that may be used for the ion gate 3 in the ion transfer tube according to the present invention. Wherein the ion transfer tube operates in the positive ion analysis period during the period in which t1, t2 and t3 are added, the potential of the first gate electrode 31 varies between v2+ and v4+, and the potential of the second gate electrode 32 is constant at v3+; the ion transfer tube operates in the negative ion analysis period during the period in which t4, t5 and t6 are added, the potential of the first gate electrode 31 is constant at V2-, and the potential of the second gate electrode 32 is changed between V3-and V4-; t1 and t4 represent the time delay time before the ion gate is closed, t2 and t5 represent the time length of the ion gate closing, and t3 and t6 represent the separation and detection time length of the injected ion holes in the migration zone.

Fig. 4 is a waveform of the potential of another gate electrode that may be used for the ion gate 3 in the ion transfer tube disclosed in the present invention. Wherein the ion transfer tube operates in a positive ion analysis period during the period in which t1, t2 and t3 are added, the potential of the first gate electrode 31 is constant at v2+, and the potential of the second gate electrode 32 varies between v3+ and v5+; in the period of addition of t4, t5 and t6, the ion transfer tube operates in the negative ion analysis period, the potential of the first gate electrode 31 is changed between V2-and V5-, and the potential of the second gate electrode 32 is constant to V3-; t1 and t4 represent the time delay time before the ion gate is closed, t2 and t5 represent the time length of the ion gate closing, and t3 and t6 represent the separation and detection time length of the injected ion holes in the migration zone.

Fig. 5 is a graph showing the positive and negative ion mobility spectra obtained for the disclosed ion mobility tube using the gate electrode potential waveforms shown in fig. 3.

Detailed Description

The following non-limiting examples will enable those of ordinary skill in the art to more fully understand the invention and are not intended to limit the invention in any way. The invention is described in further detail below with reference to the accompanying drawings.

In the description of the present invention, it should be understood that the azimuth or positional relationships indicated by the azimuth terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal", and "top, bottom", etc., are generally based on the azimuth or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify the description, and these azimuth terms do not indicate and imply that the apparatus or elements referred to must have a specific azimuth or be constructed and operated in a specific azimuth, and thus should not be construed as limiting the scope of protection of the present invention: the orientation word "inner and outer" refers to inner and outer relative to the contour of the respective component itself.

Example 1

The polarity switching ion migration tube disclosed by the invention is shown in fig. 1. The ion source 1 of the ion migration tube is a single-end closed metal cylinder with the outer diameter of 30mm, the inner diameter of 10mm and the axial length of 12mm, and the surface of the inner cavity is provided with radioactivity ⁶³ A Ni coating; a sample gas inlet 13 and a gas outlet 14 with the aperture of 2mm are welded on the ion source 1; the ionization region 2 and the migration region 4 are formed by alternately overlapping annular electrodes 6 with the thickness of 4mm, the inner diameter of 18mm and the outer diameter of 30mm and annular insulators 7 with the thickness of 1mm, the inner diameter of 18mm and the outer diameter of 30mm, the axial length of the ionization region 2 is 40mm, and the axial length of the migration region 4 is 60mm; the ion gate 3 is formed by alternately superposing a first gate electrode 31, an annular insulator 7 and a first gate electrode 32 coaxially, wherein the first gate electrode 31 and the first gate electrode 32 are annular electrodes with the outer diameter of 30mm, the inner diameter of 18mm and the thickness of 0.05mm, and the diameter of 18mm and the thickness of 0.05mm are arranged in an inner through hole of the annular electrodeA round metal grid with the degree of 0.5 mm; the ion receiving electrode 5 is a Faraday disc with the diameter of 6mm, is fixed on a metal shielding cylinder with the outer diameter of 30mm and the thickness of 5mm in an insulating sealing manner, and a drift gas inlet 12 with the aperture of 2mm is welded on the ion receiving electrode 5;

the voltage dividing resistor chain 8 is formed by connecting 2MΩ noninductive resistors in series, and the connection points between two ends of the resistor chain 8 and adjacent resistors are electrical connection points; the high-voltage power supply 9 is a positive-negative switching power supply, as shown in fig. 2, the positive potential V1+ of the power supply output is adjustable between 0 and 8000V, the negative potential V1-is adjustable between-8000 and 0V, and the positive-negative switching frequency of the power supply output is adjustable between 1 and 200 Hz; the first isolation high-voltage pulse power supply 10 and the second isolation high-voltage pulse power supply 11 are isolation high-voltage pulse power supplies with adjustable isolation withstand voltage 10000V and output pulse amplitude of 0-500V;

The ion source 1, the annular electrode 6 of the ionization region 2, the reference voltage input end of the first isolated high-voltage pulse power supply 10, the reference voltage input end of the second isolated high-voltage pulse power supply 11, the annular electrode 6 of the migration region 4 and the electrical connection points of the ion receiving electrode 5 and the voltage dividing resistor chain 8 are sequentially connected in a one-to-one correspondence manner; the electrical connection point of the voltage dividing resistor chain 8, which is close to one end of the ion source 1, is connected with the high-voltage output end of the high-voltage power supply 9, and the electrical connection point of the voltage dividing resistor chain 8, which is close to one end of the ion receiving electrode 5, is connected with the ground voltage output terminal of the high-voltage power supply 9 and the ground;

the high voltage pulse output end of the first isolated high voltage pulse power supply 10 is connected with the first gate electrode 31, and the high voltage pulse output end of the second isolated high voltage pulse power supply 11 is connected with the second gate electrode 32, so that ion gate potential waveforms as shown in fig. 3 or fig. 4 are applied to the first gate electrode 31 and the second gate electrode 32 of the ion gate 3;

when the ion gating potential waveform shown in fig. 3 is adopted, the high-voltage power supply 9 outputs positive potential v1+ within a first preset time interval t1, the first gate electrode 31 applies positive potential v2+, the second gate electrode 32 applies positive potential v3+, a direct current electric field is formed inside the ion transfer tube along the direction from the ion source 1 to the ion receiving electrode 5, positive ions generated by the ion source 1 are transferred along the direction from the ion source 1 to the ion receiving electrode 5 and fully fill the ion transfer tube, continuous positive ion flow is formed, and the inner wall of the transfer region 4 rapidly reaches positive charge balance;

In a second preset time interval t2, the high-voltage power supply 9 outputs positive potential V1+, the positive potential applied by the first gate electrode 31 is reduced from V2 < + > to V4 < + >, the positive potential V3 < + > is applied by the second gate electrode 32, a direct current electric field along the direction from the ion receiving electrode 5 to the ion source 1 is formed between the first gate electrode 31 and the second gate electrode 32, positive ions between the first gate electrode 31 and the second gate electrode 32 migrate towards the first gate electrode 31 and annihilate on the first gate electrode 31, and ion holes without ions exist are formed between the first gate electrode 31 and the second gate electrode 32;

in a third preset time interval t3, the high-voltage power supply outputs positive potential V1+, positive potential applied by the first gate electrode 31 is raised from V4+ to V2+, positive potential V3+ is applied by the second gate electrode 32, a direct current electric field along the direction from the ion source 1 to the ion receiving electrode 5 is formed inside the ion transfer tube, and ion holes between the first gate electrode 31 and the second gate electrode 32 enter the transfer region 4 along with positive ion flow and are transferred towards the ion receiving electrode 5, and finally are detected by the ion receiving electrode 5, so that a positive ion transfer spectrogram is formed;

in a fourth preset time interval t4, the high-voltage power supply outputs negative potential V1-, the first gate electrode 31 applies negative potential V2-, the second gate electrode 32 applies negative potential V3-, a direct current electric field is formed in the ion transfer tube along the direction from the ion receiving electrode 5 to the ion source 1, negative ions generated by the ion source 1 are transferred along the direction from the ion source 1 to the ion receiving electrode 5 and fully fill the interior of the ion transfer tube to form continuous negative ion flow, and the inner wall of the transfer region 4 rapidly reaches negative charge balance;

In a fifth preset time interval t5, the high-voltage power supply outputs a negative potential V1-, the first gate electrode 31 applies a negative potential V2-, the negative potential applied by the second gate electrode 32 is reduced from V3-to V4-, a direct current electric field along the direction from the ion source 1 to the ion receiving electrode 5 is formed between the first gate electrode 31 and the second gate electrode 32, negative ions between the first gate electrode 31 and the second gate electrode 32 migrate towards the first gate electrode 31 and annihilate on the first gate electrode 31, and ion holes without ions exist between the first gate electrode 31 and the second gate electrode 32 are formed;

in a sixth preset time interval t6, the high-voltage power supply outputs a negative potential V1-, the first gate electrode 31 applies a negative potential V2-, the negative potential applied by the second gate electrode 32 rises from V4-to V3-, a direct current electric field is formed in the ion transfer tube along the direction from the ion receiving electrode 5 to the ion source 1, and ion holes between the first gate electrode 31 and the second gate electrode 32 enter the transfer region 4 along with negative ion flow and are transferred towards the ion receiving electrode 5, and finally are detected by the ion receiving electrode 5 to form a negative ion transfer spectrogram;

when the ion gating potential waveform shown in fig. 4 is adopted, the high-voltage power supply outputs positive potential v1+ within a first preset time interval t1, the first gate electrode 31 applies positive potential v2+ and the second gate electrode 32 applies positive potential v3+, a direct current electric field is formed in the ion transfer tube along the direction from the ion source 1 to the ion receiving electrode 5, positive ions generated by the ion source 1 are transferred along the direction from the ion source 1 to the ion receiving electrode 5 and fully fill the ion transfer tube to form continuous positive ion flow, and the inner wall of the transfer region 4 rapidly reaches positive charge balance;

In a second preset time interval t2, the high-voltage power supply outputs positive potential V1 < + >, the first gate electrode 31 applies positive potential V2 < + >, the positive potential applied by the second gate electrode 32 rises from V3 < + > to V5 < + >, a direct current electric field is formed between the first gate electrode 31 and the second gate electrode 32 along the direction from the ion receiving electrode 5 to the ion source 1, positive ions between the first gate electrode 31 and the second gate electrode 32 migrate towards the first gate electrode 31 and annihilate on the first gate electrode 31, and ion holes without ions exist between the first gate electrode 31 and the second gate electrode 32;

in a third preset time interval t3, the high-voltage power supply outputs positive potential V1+, positive potential V2+ is applied by the first gate electrode 31, positive potential applied by the second gate electrode 32 is reduced from V5+ to V3+, a direct current electric field along the direction from the ion source 1 to the ion receiving electrode 5 is formed in the ion transfer tube, and ion holes between the first gate electrode 31 and the second gate electrode 32 enter the transfer region 4 along with positive ion flow and are transferred towards the ion receiving electrode 5, and finally are detected by the ion receiving electrode 5, so that a positive ion transfer spectrogram is formed;

in a fourth preset time interval t4, the high-voltage power supply outputs negative potential V1-, the first gate electrode 31 applies negative potential V2-, the second gate electrode 32 applies negative potential V3-, a direct current electric field is formed in the ion migration tube along the direction from the ion receiving electrode 5 to the ion source 1, negative ions generated by the ion source 1 migrate along the direction from the ion source 1 to the ion receiving electrode 5 and are filled in the ion migration tube to form continuous negative ion flow, and the inner wall of the migration region (4) rapidly reaches negative charge balance;

In a fifth preset time interval t5, the high-voltage power supply outputs a negative potential V1-, the negative potential applied by the first gate electrode 31 is increased from V2-to V5-, the negative potential V3-is applied by the second gate electrode 32, a direct current electric field along the direction from the ion source 1 to the ion receiving electrode 5 is formed between the first gate electrode 31 and the second gate electrode 32, negative ions between the first gate electrode 31 and the second gate electrode 32 migrate towards the first gate electrode 31 and annihilate on the first gate electrode 31, and ion holes without ions exist between the first gate electrode 31 and the second gate electrode 32 are formed;

in a sixth preset time interval t6, the high-voltage power supply outputs negative potential V1-, the negative potential V5-applied by the first gate electrode 31 is reduced to V2-, the negative potential V3-applied by the second gate electrode 32, a direct current electric field along the direction from the ion receiving electrode 5 to the ion source 1 is formed in the ion transfer tube, and ion holes between the first gate electrode 31 and the second gate electrode 32 enter the transfer region 4 along with negative ion flow and are transferred towards the ion receiving electrode 5, and finally are detected by the ion receiving electrode 5 to form a negative ion transfer spectrogram;

the potentials V1-, V4-, V2-, V3-, and V5-are of negative polarity, i.e., the values of the potentials V1-, V4-, V2-, V3-, and V5-are less than 0, the potentials V4+, V3+, V2+, V5+ and V1+ are of positive polarity, i.e., the values of V4+, V3+, V2+, V5+ and V1+ are greater than 0, the potentials V1-, V4-, V2-, V3-, V5-, 0, V4+, V3+, V2+, V5+ and V1+ are sequentially increased;

The time interval t1 is 1-3 ms, the time interval t2 is 0.01-0.2 ms, the time interval t3 is 3-25 ms, the time interval t4 is 1-3 ms, the time interval t5 is 0.01-0.2 ms, and the time interval t6 is 3-25 ms;

the addition of t1, t2 and t3 forms a positive ion analysis period of the polarity switching ion transfer tube, the addition of t4, t5 and t6 forms a negative ion analysis period of the polarity switching ion transfer tube, and the addition of t1, t2, t3, t4, t5 and t6 forms a complete time period of the operation of the polarity switching ion transfer tube;

when the ion transfer tube works, the electric potentials output by the high-voltage power supply 9, the first isolation high-voltage pulse power supply 10 and the second isolation high-voltage pulse power supply 11 are periodically and circularly regulated according to the time period;

one path of 500mL/min of bleaching gas enters the ion migration tube through the bleaching gas inlet 12, flows into the ionization region 2 through the ion gate 3, is mixed with one path of 100mL/min of sample gas entering the ionization region 2 through the sample gas inlet 13, then flows out of the ion migration tube through the gas outlet 14, the bleaching gas is clean air which is sequentially filtered by activated carbon and 13X molecular sieves, and the sample gas is clean air containing target analytes with specific concentration.

Example 2

The ion transfer tube was switched based on the polarity disclosed in example 1, and the gate electrode potential waveform shown in fig. 3 was employed. Meanwhile, the positive potential V1 < + > output by the high-voltage power supply 9 is set to be 5000V, V < - > to be-5000V; setting time intervals t1=2 ms, t2=0.05 ms, t3=10 ms, t4=2 ms, t5=0.05 ms, t6=10 ms; setting the gate electrode potential values v2+ =3200v, v3+ =3000V, v4+ =2900v, v4- = -3300v, v2- = -3200v, v3- = -3000V in the ion gate 3; the temperature of the ion transfer tube was set to 100℃and the flow rate of the rinse gas was 500mL/min for clean air, and the sample gas was 100mL/min for clean air containing 20ppb acetone, and positive and negative ion transfer spectra were obtained as shown in FIG. 5.

In fig. 5, the positive ion spectrum (a) can observe an acetone ion peak (migration time 13.83 ms), and the negative ion spectrum (b) can observe an oxygen ion peak (migration time 10.93 ms).

In addition, after the polarity switching ion migration tube continuously works for 2 hours according to the parameters, the output of the high-voltage power supply 9 is suddenly turned off and kept for 1 hour, then the high-voltage power supply 9 is turned on again, the change trend of the migration time of the acetone ion peak and the oxygen ion peak in the graph 5 within 10 minutes of starting is continuously recorded, and the result shows that the deviation of the migration time of the two ion peaks is kept within 0.1 percent.

Claims (5)

1. The utility model provides a polarity switching ion migration tube, ion migration tube comprises ion source (1), ionization zone (2), ion gate (3), migration zone (4) and ion receiving pole (5) that from left to right coaxial setting in proper order, its characterized in that:

the ionization region (2) and the migration region (4) are cylindrical hollow cavities formed by alternately and coaxially overlapping more than 3 circular ring-shaped electrodes (6) and more than 2 circular ring-shaped insulators (7) from left to right in sequence respectively; the ion gate (3) is formed by sequentially and coaxially overlapping a circular first gate electrode (31), a circular insulator (7) and a circular second gate electrode (32), and circular metal grids which are coaxial with the gate electrodes and can penetrate ions are respectively arranged in middle through holes of the first gate electrode (31) and the second gate electrode (32);

The ion gate (3) is positioned between the ionization region (2) at the left side and the migration region (4) at the right side, the ionization region (2) is coaxially and hermetically connected with a first gate electrode (31) of the ion gate (3) through a circular insulator (7), the migration region (4) is coaxially and hermetically connected with a second gate electrode (32) of the ion gate (3) through the circular insulator (7), the ion source (1) positioned at the left side of the ionization region (2) is hermetically connected with the ionization region (2) through the circular insulator (7), the ion receiving electrode (5) positioned at the right side of the migration region (4) is hermetically connected with the migration region (4) through the circular insulator (7), the ion receiving electrode (5) is provided with a floating gas inlet (12), and the ion source (1) is provided with a sample gas inlet (13) and a gas outlet (14);

the voltage dividing resistor chain (8) is formed by connecting more than 5 equal-resistance resistors in series in sequence, the connection points between the two ends of the voltage dividing resistor chain (8) and the adjacent resistors are electrical connection points, the electrical connection points of the end, close to the ion source (1), of the ion source (1) and the ionization region (2) are connected with the high-voltage output end of the high-voltage power source (9) in a one-to-one correspondence manner along the direction from the ion source (1) to the ion receiving electrode (5), the reference voltage input end of the first isolated high-voltage pulse power source (10), the reference voltage input end of the second isolated high-voltage pulse power source (11), the electrical connection points of the annular electrode (6) and the ion receiving electrode (5) of the migration region (4) and the voltage dividing resistor chain (8) are connected with the high-voltage output end of the high-voltage power source (9), and the electrical connection points of the end, close to the ion receiving electrode (8), of the high-voltage output end of the high-voltage power source (9) is connected with the ground;

The high-voltage pulse output end of the first isolation high-voltage pulse power supply (10) is connected with the first gate electrode (31), the high-voltage pulse output end of the second isolation high-voltage pulse power supply (11) is connected with the second gate electrode (32), the first isolation high-voltage pulse power supply (10) and the second isolation high-voltage pulse power supply (11) work cooperatively to control the electric potential of the first gate electrode (31) and the second gate electrode (32), ion holes accompanied with continuous ion flow migration are formed in the ion migration tube, and separation and detection of different ions with ion migration rate K are realized;

the method comprises the steps that in a first preset time interval t1, a second preset time interval t2 and a third preset time interval t3, a high-voltage power supply (9) outputs positive potential, a first isolation high-voltage pulse power supply (10) and a second isolation high-voltage pulse power supply (11) modulate the potential on a first gate electrode (31) and a second gate electrode (32) simultaneously according to the sequence of the first preset time interval t1, the second preset time interval t2 and the third preset time interval t3, the ion gate (3) is controlled to be sequentially switched between an on state, a off state and an on state, ion holes are formed in continuous positive ion flow in an ion migration tube, and the ion holes are injected into a migration zone to conduct reverse ion separation and detection, so that a positive ion migration spectrogram is obtained;

And in a fourth preset time interval t4, a fifth preset time interval t5 and a sixth preset time interval t6, the high-voltage power supply (9) outputs negative potential, the first isolation high-voltage pulse power supply (10) and the second isolation high-voltage pulse power supply (11) modulate the potentials on the first gate electrode (31) and the second gate electrode (32) simultaneously according to the sequence of the fourth preset time interval t4, the fifth preset time interval t5 and the sixth preset time interval t6, and the ion gate (3) is controlled to be sequentially switched among the three states of opening, closing and opening, ion holes are formed in continuous negative ion flow in the ion migration tube, and reverse ion separation and detection are carried out in the migration zone, so that a negative ion migration spectrogram is obtained.

2. The polarity-switching ion transfer tube of claim 1, wherein:

in a first preset time interval t1, the high-voltage power supply (9) outputs positive potential V1 < + >, the first isolated high-voltage pulse power supply (10) outputs positive potential V2 < + >, the second isolated high-voltage pulse power supply (11) outputs positive potential V3 < + >, a direct current electric field along the direction from the ion source (1) to the ion receiving electrode (5) is formed in the ionization region (2) and the migration region (4), a direct current electric field along the direction from the ion source (1) to the ion receiving electrode (5) is formed between the first gate electrode (31) and the second gate electrode (32), positive ions generated by the ion source (1) migrate along the direction from the ion source (1) to the ion receiving electrode (5) and are filled in the ion migration tube, continuous positive ion flow is formed, and the inner wall of the migration region (4) rapidly reaches positive charge deposition balance;

In a second preset time interval t2, the positive potential V1+ is output by the high-voltage power supply (9), the positive potential is reduced from V2+ to V4+ by the first isolated high-voltage pulse power supply (10), the positive potential V3+ is output by the second isolated high-voltage pulse power supply (11), a direct current electric field from the ion source (1) to the ion receiving electrode (5) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed between the first gate electrode (31) and the second gate electrode (32), positive ions between the first gate electrode (31) and the second gate electrode (32) migrate towards the first gate electrode (31) and annihilate on the first gate electrode (31), and ion holes without ions are formed between the first gate electrode (31) and the second gate electrode (32);

in a third preset time interval t3, the high-voltage power supply (9) outputs positive potential V1+, the positive potential output by the first isolation high-voltage pulse power supply (10) is increased from V4+ to V2+, the positive potential V3+ output by the second isolation high-voltage pulse power supply (11), the ionization region (2) and the migration region (4) form a direct current electric field along the direction from the ion source (1) to the ion receiving electrode (5), a direct current electric field along the direction from the ion source (1) to the ion receiving electrode (5) is formed between the first gate electrode (31) and the second gate electrode (32), and ion holes between the first gate electrode (31) and the second gate electrode (32) enter the migration region (4) along with positive ion flow and migrate towards the ion receiving electrode (5) and are finally detected by the ion receiving electrode (5) to form a positive ion migration spectrum;

In a fourth preset time interval t4, the high-voltage power supply (9) outputs a negative potential V1-, the first isolated high-voltage pulse power supply (10) outputs a negative potential V2-, the second isolated high-voltage pulse power supply (11) outputs a negative potential V3-, a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed between the first gate electrode (31) and the second gate electrode (32), negative ions generated by the ion source (1) migrate along the direction from the ion source (1) to the ion receiving electrode (5) and are filled in the ion migration tube, so that continuous negative ion flow is formed, and the inner wall of the migration region (4) rapidly reaches negative charge deposition balance;

in a fifth preset time interval t5, the high-voltage power supply (9) outputs a negative potential V1-, the first isolated high-voltage pulse power supply (10) outputs a negative potential V2-, the second isolated high-voltage pulse power supply (11) outputs a negative potential which is reduced from V3-to V4-, a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion source (1) to the ion receiving electrode (5) is formed between the first gate electrode (31) and the second gate electrode (32), negative ions between the first gate electrode (31) and the second gate electrode (32) migrate towards the first gate electrode (31) and annihilate on the first gate electrode (31), and ion holes without ions are formed between the first gate electrode (31) and the second gate electrode (32);

In a sixth preset time interval t6, the high-voltage power supply (9) outputs a negative potential V1-, the first isolated high-voltage pulse power supply (10) outputs a negative potential V2-, the second isolated high-voltage pulse power supply (11) outputs a negative potential which is increased from V4-to V3-, a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed between the first gate electrode (31) and the second gate electrode (32), and ion holes between the first gate electrode (31) and the second gate electrode (32) enter the migration region (4) along with negative ion flow and migrate towards the ion receiving electrode (5), and finally are detected by the ion receiving electrode (5) to form a negative ion migration spectrogram;

or, in a first preset time interval t1, the high-voltage power supply (9) outputs positive potential V1 < + >, the first isolated high-voltage pulse power supply (10) outputs positive potential V2 < + >, the second isolated high-voltage pulse power supply (11) outputs positive potential V3 < + >, the ionization region (2) and the migration region (4) form direct current electric fields from the ion source (1) to the ion receiving electrode (5), a direct current electric field from the ion source (1) to the ion receiving electrode (5) is formed between the first gate electrode (31) and the second gate electrode (32), positive ions generated by the ion source (1) migrate along the direction from the ion source (1) to the ion receiving electrode (5) and are filled in the ion migration tube to form continuous positive ion flows, and the inner wall of the migration region (4) rapidly reaches positive charge deposition balance;

In a second preset time interval t2, the high-voltage power supply (9) outputs positive potential V1 < + >, the first isolated high-voltage pulse power supply (10) outputs positive potential V2 < + >, the second isolated high-voltage pulse power supply (11) outputs positive potential which is increased from V3 < + > to V5 < + >, a direct current electric field from the ion source (1) to the ion receiving electrode (5) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed between the first gate electrode (31) and the second gate electrode (32), positive ions between the first gate electrode (31) and the second gate electrode (32) migrate towards the first gate electrode (31) and annihilate on the first gate electrode (31), and ion holes without ions are formed between the first gate electrode (31) and the second gate electrode (32);

in a third preset time interval t3, the high-voltage power supply (9) outputs positive potential V1 < + >, the first isolated high-voltage pulse power supply (10) outputs positive potential V2 < + >, the second isolated high-voltage pulse power supply (11) outputs positive potential which is reduced from V5 < + > to V3 < + >, the ionization region (2) and the migration region (4) form direct current electric fields in the direction from the ion source (1) to the ion receiving electrode (5), a direct current electric field in the direction from the ion source (1) to the ion receiving electrode (5) is formed between the first gate electrode (31) and the second gate electrode (32), and ion holes between the first gate electrode (31) and the second gate electrode (32) enter the migration region (4) along with positive ion current and migrate towards the ion receiving electrode (5) and are finally detected by the ion receiving electrode (5) to form a positive ion migration spectrum;

In a fourth preset time interval t4, the high-voltage power supply (9) outputs a negative potential V1-, the first isolated high-voltage pulse power supply (10) outputs a negative potential V2-, the second isolated high-voltage pulse power supply (11) outputs a negative potential V3-, a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed between the first gate electrode (31) and the second gate electrode (32), negative ions generated by the ion source (1) migrate along the direction from the ion source (1) to the ion receiving electrode (5) and are filled in the ion migration tube, so that continuous negative ion flow is formed, and the inner wall of the migration region (4) rapidly reaches negative charge deposition balance;

in a fifth preset time interval t5, the high-voltage power supply (9) outputs a negative potential V1-, the negative potential output by the first isolation high-voltage pulse power supply (10) is increased from V2-to V5-, the second isolation high-voltage pulse power supply (11) outputs a negative potential V3-, a direct current electric field along the direction from the ion receiving electrode (5) to the ion source (1) is formed in the ionization region (2) and the migration region (4), a direct current electric field along the direction from the ion source (1) to the ion receiving electrode (5) is formed between the first gate electrode (31) and the second gate electrode (32), negative ions between the first gate electrode (31) and the second gate electrode (32) migrate towards the first gate electrode (31) and annihilate on the first gate electrode (31), and ion holes without ions are formed between the first gate electrode (31) and the second gate electrode (32);

In a sixth preset time interval t6, the high-voltage power supply (9) outputs negative potential V1-, the negative potential output by the first isolation high-voltage pulse power supply (10) is reduced from V5-to V2-, the negative potential V3-is output by the second isolation high-voltage pulse power supply (11), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed in the ionization region (2) and the migration region (4), a direct current electric field from the ion receiving electrode (5) to the ion source (1) is formed between the first gate electrode (31) and the second gate electrode (32), and ion holes between the first gate electrode (31) and the second gate electrode (32) enter the migration region (4) along with the negative ion flow and migrate towards the ion receiving electrode (5), and finally are detected by the ion receiving electrode (5) to form a negative ion migration spectrogram.

3. The polarity-switching ion transfer tube of claim 2, wherein: the potentials V1-, V4-, V2-, V3-and V5-are of negative polarity, i.e. the values of the potentials V1-, V4-, V2-, V3-and V5-are smaller than 0, the potentials V4+, V3+, V2+, V5+ and V1+ are of positive polarity, i.e. the values of V4+, V3+, V2+, V5+ and V1+ are larger than 0, the potentials V1-, V4-, V2-, V3-, V5-, 0, V4+, V3+, V2+, V5+ and V1+ are successively increased.

4. The polarity-switching ion transfer tube of claim 2, wherein:

The first preset time interval t1 is 1-3 ms, the second preset time interval t2 is 0.01-0.2 ms, the third preset time interval t3 is 3-25 ms, the fourth preset time interval t4 is 1-3 ms, the fifth preset time interval t5 is 0.01-0.2 ms, and the sixth preset time interval t6 is 3-25 ms.

5. The polarity-switching ion transfer tube of any of claims 1-4, wherein:

the positive ion analysis period of the polarity switching ion transfer tube is formed by the summation of a first preset time interval t1, a second preset time interval t2 and a third preset time interval t3, the negative ion analysis period of the polarity switching ion transfer tube is formed by the summation of a fourth preset time interval t4, a fifth preset time interval t5 and a sixth preset time interval t6, and a complete time period of the polarity switching ion transfer tube is formed by the summation of the first preset time interval t1, the second preset time interval t2, the third preset time interval t3, the fourth preset time interval t4, the fifth preset time interval t5 and the sixth preset time interval t 6;

when the ion transfer tube works, the electric potential output by the high-voltage power supply (9), the first isolated high-voltage pulse power supply (10) and the second isolated high-voltage pulse power supply (11) is periodically and circularly regulated according to the time period;

One path of bleaching gas enters the ion migration tube through the bleaching gas inlet (12), flows into the ionization region (2) through the ion gate (3), is mixed with one path of sample gas entering the ionization region (2) through the sample gas inlet (13), then flows out of the ion migration tube through the gas outlet (14), and is clean air which is sequentially filtered through activated carbon and a 13X molecular sieve, and the sample gas is clean air containing target analytes with specific concentration.