CN214067013U

CN214067013U - High-selectivity ion mobility spectrum for on-line monitoring of benzene series in soil

Info

Publication number: CN214067013U
Application number: CN202022821081.5U
Authority: CN
Inventors: 代渐雄; 刘岩; 段忆翔
Original assignee: Northwestern University
Current assignee: Northwestern University
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2021-08-27
Anticipated expiration: 2030-11-30

Abstract

The utility model discloses an ion mobility spectrometry adopts ultraviolet lamp light ionization source, uses multichannel filtration membrane, makes ion mobility spectrometry have dual selectivity, can be used to benzene series thing and polycyclic aromatic hydrocarbon in the complicated matrix environment, carries out witnessed inspections or on-line monitoring like benzene series thing in the soil, polycyclic aromatic hydrocarbon. The utility model discloses utilize multichannel membrane module to carry out the primary separation with the stronger impurity of polarity, ultraviolet lamp selectivity ionization carries out the secondary selection, makes the instrument have dual selectivity. The multi-channel membrane component is placed in a self-designed internal circulation closed heat-insulating cavity, so that the permeation of a target compound is accelerated, and the separation efficiency of the multi-channel membrane component is improved. The ion mobility spectrometry adopts the design of uniformly distributing the three ultraviolet lamps on the circumference, and can improve the ionization efficiency of the ion source. The utility model discloses can be applied to the on-line monitoring of benzene series thing in the soil, it is more convenient fast to compare with the traditional approach that detects benzene series thing, helps soil benzene series thing pollution control work.

Description

High-selectivity ion mobility spectrum for on-line monitoring of benzene series in soil

Technical Field

The utility model relates to an analytical instrument technical field, concretely relates to a high selectivity ion mobility spectrometry that is arranged in benzene series thing on-line measuring in soil.

Background

Benzene series is one of main pollutants causing soil pollution in organic chemical leakage, and benzene series is easily brought into the environment by petroleum, chemical coking and other behaviors, so that the benzene series entering the environment can cause great harm to human bodies. The soil is the main destination of environmental pollutants, and benzene series pollutants can easily enter the soil environment to cause pollution to the soil environment, so that the development of detection research on the benzene series in the soil has important significance.

The existing technologies for detecting the benzene series in the soil include Gas Chromatography (GC), Liquid Chromatography (LC), gas chromatography and mass spectrometry (GC-MS) and the like, and the technologies have advantages and disadvantages, and for the two chromatographic technologies, namely the gas chromatography and the liquid chromatography, the two chromatographic technologies have fatal defects, namely long response time, cannot be analyzed on line, and cannot be detected outdoors. The GC-MS mainly exerts the advantages of mass spectrum, but the mass spectrum has the defects of complicated mass analyzer, large volume, strict working environment and high price due to the need of vacuum, and is difficult to apply to online monitoring. Ion mobility spectrometry can be used to solve problems in order to achieve detection anytime and anywhere.

Ion Mobility Spectrometry (IMS) is an atmospheric pressure analysis technique developed in the 70 th 20 th century, and its working principle is that charged ions have different migration rates in a weak electric field, resulting in different time reaching a detector, thereby performing separation analysis. Compared with the technologies, the ion mobility spectrometry has the advantages of high sensitivity, low cost, quick response time, small volume and portability, and can be well made into a portable instrument to be applied to the online monitoring of the benzene series in the soil.

The IMS generally consists of a sample introduction, an ion source region, an ion gate, a drift region, a gas path system, and a signal acquisition and processing system. The ion source is important for the IMS, and the ultraviolet lamp ion source can be selectively ionized when used as a positive ion mode, and can ionize substances with ionization energy lower than the photon energy of the ultraviolet lamp, so that the selection performance of the ion mobility spectrometry is enhanced. For the detection of benzene series in soil, an ultraviolet lamp is used as an ion source, the interference of some impurity gases (molecules with ionization energy higher than the photon energy of the ultraviolet lamp) can be eliminated, but if the gas to be detected is directly introduced into an ion mobility spectrum, the impurity gases have serious influence on the detection result, such as water molecules in the air, and the ionization efficiency can be reduced by humid air, so that the sensitivity and the resolution are influenced. If the membrane is adopted to directly filter impurities for sample injection, the defect 1: the specific surface area is not very large, the impurity removing effect is not good, and the defects are overcome. 2: short service life, frequent replacement and unsuitability for on-line monitoring. Such ion mobility spectrometry is not highly selective, and the resolution of the obtained spectrum is not high. 3: the influence of the external temperature on the permeation of the membrane module is considered in the online monitoring.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an ion mobility spectrometry with high selectivity uses its on-line measuring at benzene series thing in soil to can be convenient be applied to witnessed inspections, on-line monitoring, it is little to overcome diaphragm specific surface, need repeated shortcoming of changing, combines the selectivity ionization advantage of ultraviolet lamp ion source simultaneously, gets rid of the interference of other gaseous impurities, makes ion mobility spectrometry detect specific substance-this type of compound of benzene series thing have better resolution ratio, sensitivity, thereby widens the range of application of instrument.

To achieve the above object, the utility model adopts the following solution:

the utility model provides a can be used to high selectivity ion mobility spectrometry of benzene series thing on-line monitoring in soil, includes multichannel membrane module, introduction port, ion source region, ion source, ion gate, drift region, gas circuit system, signal amplification collection and data processing system, its characterized in that: the multichannel membrane module includes two inner loop ports and three sample circulation port, soil sample headspace gas circuit and two exhaust gas discharge mouth are connected respectively to three sample circulation port, and ion mobility spectrum and carrier gas circuit are connected respectively to two inner loop ports, the introduction port is connected with the ion source region is coaxial, the ion source adopts three ultraviolet lamp, ion source region, ion gate, drift region are coaxial arrangement in proper order and are connected, drift pipe is constituteed to ion source region, ion gate, drift region lateral wall winding conducting ring, and adjacent conducting ring regards as the insulator ring with the quartz capsule, contain the Faraday cup in the drift region with the drift pipe is coaxial and is connected with signal amplification collection and data processing system, the gas circuit system will adopt gas circuit inner loop system, regards air-purifying as carrier gas and floats the gas.

Three sample circulation ports of the multi-channel membrane component are respectively connected with a soil sample headspace gas circuit and two waste gas discharge ports, and two internal circulation ports are respectively connected with an ion mobility spectrometry and a carrier gas circuit. The ion mobility spectrometer can be used for on-site detection or on-line monitoring of soil benzene series and polycyclic aromatic hydrocarbon compounds.

The multi-channel membrane component has large specific surface area and relatively weak polarity, and is placed in the closed internal circulation type heat-insulating cavity.

The gas flow in the closed internal circulation type heat-insulating cavity is internal circulation, the temperature is balanced in the cavity, the permeation of a target compound is accelerated, and the separation efficiency of the multi-channel membrane component is improved.

The first selective permeation is carried out through the multi-channel membrane component, water molecules, ammonia and other molecules with strong polarity in the sample gas are discharged as impurity gas, and the gas with relatively weak polarity of benzene series passes through the multi-channel membrane component and permeates to the other end of the membrane to be brought into the ion mobility spectrometry by carrier gas.

The included angles between the three ultraviolet lamps and the horizontal position range from 73 degrees to 80 degrees, and the inner diameter is 25 mm.

A plurality of dispersing air inlets are formed in the ion source inlet of the ion mobility spectrometry, so that overlarge air flow is prevented, and the flow speed of the air is reduced.

The dispersion air inlet is coaxially connected with the ion source region, and the carrier gas carries the sample gas to directly enter the ion source region.

By adopting the proposal, the utility model has the characteristics of it is following:

1. by utilizing the multi-channel membrane module filtering system, the specific surface area is increased, the service life is prolonged, repeated replacement is not needed, and meanwhile, gases with strong polarity, such as water molecules, amine molecules and other gas molecules in the sample gas can be filtered and selected for the first time.

2. The gas after membrane filtration is selectively ionized by an ultraviolet lamp ion source, the soil benzene series to be detected can be basically ionized by the ultraviolet lamp, and other non-ionized gas is discharged for the second selection.

3. The multi-channel membrane component is placed in an internal circulation type closed heat preservation cavity, the permeation of the membrane can be accelerated, meanwhile, the gas adopts an internal circulation mode, the temperature reaches certain balance in the cavity, the temperature exchange with the outside is avoided, the influence of the outside supercooling and overheating temperature on the cavity and the influence on the membrane permeation are reduced, and meanwhile, in a certain temperature range, the temperature is high, and the permeation of the membrane is better.

4. The design of three ultraviolet lamps is adopted, so that the ionization efficiency of an ionization region can be enhanced, sample substances are fully utilized, the ultraviolet lamps can be prevented from being coaxially arranged, the influence on an analysis spectrogram caused by ionization behind an ion gate can be avoided, and the resolution is improved.

5. The ion mobility spectrometry after twice selection has high selectivity, is beneficial to improving the sensitivity of the instrument, is used for on-line monitoring of the benzene series in specific substances, namely soil, and can widen the application range of the ion mobility spectrometry.

6. The ultraviolet lamp is used as an ion source, photons with specific energy are emitted by the ultraviolet lamp, the photons and molecules with ionization energy lower than photon energy are subjected to ionization, the molecules with ionization energy higher than the photon energy cannot be ionized, benzene series molecules with ionization energy lower than the photon energy are ionized in sample gas after the first selection through the PDMS membrane, and other molecules with ionization energy higher than the photon energy are not ionized, so that the ultraviolet lamp is used for selective ionization, and the selectivity is further enhanced.

7. The ion source area adopts three ultraviolet lamps to fully utilize the sample gas after the first selection through the multi-channel membrane component, so that the sample gas is fully ionized, the utilization rate of sample substances is improved, and the ionization efficiency of the ionization area is improved.

Drawings

FIG. 1 is a schematic top view of an ion source structure for ion mobility spectrometry

FIG. 2 is a schematic cross-sectional view of an ion source structure of ion mobility spectrometry

FIG. 3 is a schematic view of a multi-channel membrane module combined with three ultraviolet lamps ion mobility spectrometry

FIG. 4 is a schematic diagram of the internal structure of a multi-channel membrane module

In the figure: 1-an ion source inlet dispersing air inlet, 2-an ultraviolet lamp mounting position, 3-an ion source electrifying position, two waste gas discharge ports in three sample circulating ports of a 4-multichannel membrane module, a port connected with a sample gas circuit in three sample circulating ports of a 5-multichannel membrane module, a port connected with carrier gas in two internal circulating ports of a 6-multichannel membrane module, a port connected with an IMS (ion management system) in two internal circulating ports of a 7-multichannel membrane module, an 8-sample inlet, a 9-exhaust port, a 10-ion gate, an 11-drift tube, a 12-ion source region, a 13-drift region, a 14-conducting ring, a 15-insulating ring, a 16-drift gas inlet, a 17-Faraday disc, an 18-signal amplification acquisition and processing system, 19-a closed internal circulation type heat preservation cavity, 20-a multi-channel membrane component, 21-a multi-channel membrane component internal carrier gas carrying sample gas flowing direction, 22-a multi-channel membrane component sample gas flowing direction, 23-a multi-channel membrane component waste gas discharging flowing direction, 24-a heat preservation cavity type gas internal circulation, 25-an ion source, 26-a carrier gas flowing direction, 27-a carrier gas carrying sample gas flowing direction and 28-a sample gas flowing direction.

Detailed Description

The present invention will be further described with reference to the following detailed description.

In order to make the objects, technical solutions and advantages of the present invention clearer, the following description of the present invention will be made in detail with reference to the accompanying drawings.

Fig. 1 and 2 are a top view and a cross-sectional view of the ion mobility spectrometry ion source structure of the three ultraviolet lamps of this embodiment, the ion source region sample inlet 1 is as shown in fig. 1, the sample inlet hole at the sample inlet is a plurality of dispersed holes which are not concentrated in the center of the ion source region, and the holes disperse the sample gas carried by the carrier gas, so as to prevent the gas from concentrating into one hole and flowing too much, and the sample is directly carried into the ion gate by the gas. Like figure 2, ultraviolet lamp mounted position 2, the ultraviolet lamp hugs closely the lateral wall and guarantees that sample material makes sample material ionization abundant in the effective ionization within range of ultraviolet lamp, adopts three ultraviolet lamp simultaneously, further makes sample ionization abundant, improves sample material utilization ratio, makes ionization effect better to can improve the ion mobility spectrum and go out the peak intensity, the sensitivity of instrument is effectively improved, and the intermediate position is in the strongest region of ultraviolet lamp ionization, and 3 positions are the power-on position department of ion source region.

As shown in fig. 3, the figure is a schematic structural diagram of a multichannel membrane module combined with three ultraviolet lamps ion mobility spectrometry, and includes a closed internal circulation type heat preservation cavity 19, a multichannel membrane module 20, a sample inlet 8, an ion source 25, a drift tube 11, a gas path system, a circuit control system, and a signal amplification acquisition and signal processing system. The multi-channel membrane component is placed in a self-designed closed internal circulation type heat preservation cavity 19, and the internal circulation 24 of gas is shown in the figure, so that the influence of online monitoring of external super-cooled and overheated environments on membrane permeation can be reduced, and meanwhile, in a certain temperature range, the higher the temperature is, the better the membrane permeation effect is. The port 5 of the multi-channel membrane component is connected with a soil sample headspace gas circuit, sample headspace gas enters the multi-channel membrane component through the port 5, the polarity of the multi-channel membrane component is weak polarity, soil benzene series to be detected and some weak polarity impurities are permeated through the multi-channel membrane component, and impurity gases with strong polarity, such as water molecules, amines and other molecules, are discharged.

The port 6 is connected with the purified air as a port of the carrier gas, as shown in fig. 4, 26 represents the inflow direction of the carrier gas, the permeated sample gas is blown, 27 represents the outflow direction of the sample gas carried by the carrier gas, and the sample gas is discharged through the port 7, the port 7 is connected with the ion mobility spectrometry injection port 8, so that the sample gas after the first selection enters the ion mobility spectrometry, and the impurity gas which cannot pass through the membrane material is discharged through the two exhaust ports of the port 4. As shown in fig. 4, a schematic diagram of the membrane module is represented, wherein 21 represents a blowing direction of the sample gas carried by the blowing carrier gas through the membrane module, 22 represents a sample gas flow permeation direction, and 23 represents an exhaust gas discharge flow direction. The drift tube 11 is a hollow tube formed by alternately and tightly connecting a plurality of conducting rings 14 and insulating rings 15, and consists of an ion source region 12, an ion gate 10 and a drift region 13 which are coaxially connected. The sample inlet 8 is connected with a multi-channel membrane component, ionization is carried out through an ion source region 12, the ion source adopts an ultraviolet lamp ion source, ionized particles move towards an ion gate 10 under the action of an accelerating electrode, waste gas is discharged from an exhaust port 9, a drift region is reached under the action of opening and closing the ion gate 10, at the moment, charged particles are subjected to the acceleration action of electric field force and the deceleration action of reverse drift gas, the molecular size, the shape and the quality of a substance to be detected are different, the stress is different, the time reaching a Faraday cup 17 is different, separation detection is obtained, the obtained electric signal is amplified through an amplifier, and a corresponding data spectrogram is obtained after data processing is carried out through data acquisition by an acquisition card.

Of course, various other embodiments of the present invention are also possible, and those skilled in the art can make various corresponding changes and modifications according to the present invention without departing from the spirit and the essential attributes of the present invention, and these corresponding changes and modifications should fall within the scope of the appended claims.

Claims

1. The utility model provides a can be used to high selectivity ion mobility spectrometry of benzene series thing on-line monitoring in soil, includes multichannel membrane module, introduction port, ion source region, ion source, ion gate, drift region, gas circuit system, signal amplification collection and data processing system, its characterized in that: the multichannel membrane module includes two inner loop ports and three sample circulation port, soil sample headspace gas circuit and two exhaust gas discharge mouth are connected respectively to three sample circulation port, and ion mobility spectrum and carrier gas circuit are connected respectively to two inner loop ports, the introduction port is connected with the ion source region is coaxial, the ion source adopts three ultraviolet lamp, ion source region, ion gate, drift region are coaxial arrangement in proper order and are connected, drift pipe is constituteed to ion source region, ion gate, drift region lateral wall winding conducting ring, and adjacent conducting ring regards as the insulator ring with the quartz capsule, contain the Faraday cup in the drift region with the drift pipe is coaxial and is connected with signal amplification collection and data processing system, the gas circuit system will adopt gas circuit inner loop system, regards air-purifying as carrier gas and floats the gas.

2. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 1, which is characterized in that: three sample circulation ports of the multi-channel membrane component are respectively connected with a soil sample headspace gas circuit and two waste gas discharge ports, and two internal circulation ports are respectively connected with an ion mobility spectrometry and a carrier gas circuit.

3. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 1, which is characterized in that: the multi-channel membrane component has large specific surface area and relatively weak polarity, and is placed in the closed internal circulation type heat-insulating cavity to form a membrane component filtering system.

4. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 3, characterized in that: the gas flow in the closed internal circulation type heat preservation cavity is internal circulation, and the temperature is balanced in the cavity.

5. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 1, which is characterized in that: the first selective permeation is carried out through the multi-channel membrane component, water molecules, ammonia and other molecules with strong polarity in the sample gas are discharged as impurity gas, and the gas with relatively weak polarity of benzene series passes through the multi-channel membrane component and permeates to the other end of the membrane to be brought into the ion mobility spectrometry by carrier gas.

6. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 1, which is characterized in that: the included angles between the three ultraviolet lamps and the horizontal position range from 73 degrees to 80 degrees, and the inner diameter is 25 mm.

7. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 1, which is characterized in that: a plurality of dispersing air inlets are formed in the ion source inlet of the ion mobility spectrometry, so that overlarge air flow is prevented, and the flow speed of the air is reduced.

8. The high selectivity ion mobility spectrometry for the on-line monitoring of benzene series in soil according to claim 7, which is characterized in that: the dispersion air inlet is coaxially connected with the ion source region, and the carrier gas carries the sample gas to directly enter the ion source region.