Device and method for real-time online analysis of non-volatile organic pollutants

Abstract

The invention belongs to the technical field of online analysis of organic pollutants, and particularly relates to a device and a method for real-time online analysis of non-volatile organic pollutants. The device comprises a sample injection module, a vacuum ultraviolet lamp, an ionization source cavity, a repulsion electrode, an ion funnel, a mass analyzer and a vacuumizing module, the ionization source cavity is provided with a sample injection port, a vacuum extraction port and an ion output port, and the vacuum ultraviolet lamp, the repulsion electrode and the ion funnel are sequentially arranged in the ionization source cavity at intervals in the axis direction of the ion output port; the ion funnel is close to the ion output port; the sample injection module is arranged at the sample injection port; the vacuumizing module is arranged on the vacuum extraction opening; the ion output port is externally connected with a mass analyzer; a direct-current voltage is applied to the repulsion electrode, and a direct-current voltage and a radio-frequency voltage are applied to the ion funnel. According to the invention, the ions with relatively large initial distribution area can be focused, so that the detection sensitivity is further improved, and the detection requirements on trace non-volatile organic pollutants are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of online analysis of organic pollutants, and in particular relates to a device and method for real-time online analysis of non-volatile organic pollutants. Background Art

[0002] Photoionization source is an attractive soft ionization technology, which has the advantages of excellent ionization efficiency, high molecular ion yield and easy spectrum analysis. In addition, according to the Ludwig-Beer law, the sensitivity can be further improved by increasing the gas pressure, light flux and optical path, so it is widely used in environmental analysis, clinical diagnosis and industrial process monitoring.

[0003] When the pressure in the photoionization source is high (>100Pa), the collision and divergence between molecules and ions and the small holes between the vacuum differential chambers become the main factors limiting the ion utilization rate. Therefore, an efficient ion transmission system is one of the key technologies to improve sensitivity. The working pressure of the ion funnel is mainly 1-1000Pa, which is consistent with the working pressure of the ion source. Therefore, it is mostly used as an ion focusing device in the source, and its sensitivity can be improved by an order of magnitude.

[0004] Phthalates are a major plasticizer that is widely used in hundreds of products, including toys, food packaging materials, medical blood bags, and personal care products (such as nail polish, hair spray, soap, and shampoo). However, in recent years, the environmental health hazards caused by these compounds have received widespread attention in the fields of environmental science, public health, and even the general public. When analyzing non-volatile organic pollutants such as phthalates, due to the extremely low content of their volatile components, even using a photoionization source coupled with an ion funnel, the detection limit is difficult to meet the requirements. Therefore, there is an urgent need for a device and method for real-time online analysis of non-volatile organic pollutants. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide a device and method for real-time online analysis of non-volatile organic pollutants, so as to solve the problem that the detection limit is difficult to meet the requirements when analyzing non-volatile organic pollutants in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] On one hand, the present invention provides a device for real-time online analysis of non-volatile organic pollutants, comprising an injection module, a vacuum ultraviolet lamp, an ionization source cavity, a repeller electrode, an ion funnel, a mass analyzer and a vacuum module, wherein the ionization source cavity is provided with an injection port, a vacuum exhaust port and an ion output port, the vacuum ultraviolet lamp, the repeller electrode and the ion funnel are sequentially arranged in the ionization source cavity along the axial direction of the ion output port, and the ion funnel is close to the ion output port, and the light emitted by the light source emitting end of the vacuum ultraviolet lamp passes through the repeller electrode and the ion funnel in sequence; the injection module is arranged at the injection port to transport a sample to be provided for detection into the ionization source cavity; the vacuum module is arranged on the vacuum exhaust port to vacuum the ionization source cavity; the ion output port is externally connected to the mass analyzer; a DC voltage is applied to the repeller electrode, and a DC voltage and a radio frequency voltage are applied to the ion funnel; the sample is ionized under the action of the vacuum ultraviolet lamp, and the sample ions are focused and transmitted to the mass analyzer under the action of the repeller electrode and the ion funnel to achieve final detection and analysis.

[0008] The ion funnel comprises a plurality of annular flat plate funnel electrodes which are arranged in parallel and at equal intervals and each have a circular through hole. The aperture of the circular through hole of each annular flat plate funnel electrode decreases in sequence along the emitting direction of the vacuum ultraviolet lamp.

[0009] The DC voltage applied to the repeller electrode and each annular flat funnel electrode in the ion funnel is sequentially reduced along the direction of the light emitted from the light source emitting end of the vacuum ultraviolet lamp to form a DC gradient electric field;

[0010] Radio frequency voltage is applied to each annular flat funnel electrode in the ion funnel, and the peak-to-peak amplitudes of the radio frequencies on any two adjacent annular flat funnel electrodes are equal and the phases are opposite.

[0011] The gradient electric field of the DC gradient electric field is 2-20 V / cm; the radio frequency frequency of the radio frequency voltage is 0.5-5 MHz, and the radio frequency peak-to-peak value is 10-800 V; the number of the annular flat funnel electrodes is N, and N is an even number.

[0012] The repelling electrode is an annular flat plate structure with a circular through hole in the middle; the thickness of the repelling electrode is 2-4 mm, and the diameter of the circular through hole in the middle is 4-10 mm;

[0013] The thickness of each annular flat funnel electrode in the ion funnel is 0.5-1 mm, and the diameter of the circular through hole in the middle is 1-20 mm;

[0014] The repeller electrode and each of the annular flat plate funnel electrodes are made of conductive metal or a flat plate with a conductive metal layer plated on the surface.

[0015] The vacuum ultraviolet lamp is a low-pressure krypton lamp with a large light window diameter, and the photon emission diameter is 6-12 mm.

[0016] The injection module comprises an injection capillary, a volatilization chamber and a sample delivery tube, wherein an air inlet and an air outlet are respectively arranged on both sides of the volatilization chamber, the air inlet is externally connected to a flow meter, and the flow meter is used to control the flow of carrier gas entering the volatilization chamber; the air outlet is tightly connected to one end of the sample delivery tube, the other end of the sample delivery tube is tightly connected to one end of the injection capillary through a three-hole joint, the other end of the injection capillary penetrates into the ionization source cavity through the injection port, and extends to between the repeller electrode and the ion funnel; the sample to be tested is placed in the volatilization chamber.

[0017] The volatilization chamber, the sample delivery tube, the three-hole joint and the injection capillary are all wrapped by a heating device, and the temperature of the heating device can be adjusted between 0-200°C.

[0018] The carrier gas flowing through the flow meter is nitrogen or helium, the gas flow rate is 50-200 ml / min, and the carrier gas flow rate is greater than the injection volume of the injection capillary;

[0019] The inner diameter of the sample delivery tube is 3-6 mm, and the inner diameter of the injection capillary is 100-250 μm.

[0020] The vacuum pumping module comprises an air pressure valve and a vacuum mechanical pump; the vacuum pumping port of the ionization source cavity is connected to the air pressure valve and the vacuum mechanical pump in sequence from the inside to the outside;

[0021] The air pressure in the ionization source cavity is between 10-1000 Pa and is adjusted by an air pressure valve and a vacuum mechanical pump.

[0022] On the other hand, the present invention provides a method for real-time online analysis of non-volatile organic pollutants using the above-mentioned device, which comprises placing a sample to be tested in a volatilization chamber, setting a heating temperature, and introducing a carrier gas with a fixed flow rate into the volatilization chamber through a flow meter, wherein the carrier gas carries the volatile components of the sample to be tested and passes through a sample delivery tube, a three-hole joint, and an injection capillary in sequence into an ionization source cavity; the non-volatile components with a low content are first efficiently ionized under the action of a vacuum ultraviolet lamp with a large photon emission diameter, and then the sample ions are effectively focused under the action of a repeller electrode and an ion funnel and transmitted to a mass analyzer for final detection and analysis.

[0023] The advantages and beneficial effects of the present invention are as follows: the present invention combines an ion funnel with a photoionization source having a larger light-emitting area. Since the ion funnel has a better focusing effect, ions with a larger initial distribution area can be focused, thereby further improving the detection sensitivity to meet the detection needs of trace amounts of non-volatile organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural diagram of a device for real-time online analysis of non-volatile organic pollutants of the present invention;

[0025] Figure 2 A schematic diagram of the structure of the photoionization source of the present invention established using SIMION;

[0026] Figure 3 This is a SIMION simulation result diagram of the effect of using a photoionization source with a larger light-emitting area on sensitivity in an embodiment of the present invention.

[0027] In the figure: 1-injection capillary, 2-vacuum ultraviolet lamp, 3-ionization source chamber, 4-repelling electrode, 5-air pressure valve, 6-vacuum mechanical pump, 7-ion funnel, 8-mass analyzer, 9-flow meter, 10-volatilization chamber, 11-sample to be tested, 12-sample delivery tube, 13-three-hole connector. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] See also Figure 1 As shown, the present invention provides a device for real-time online analysis of non-volatile organic pollutants, comprising a sample injection module, a vacuum ultraviolet lamp 2, an ionization source cavity 3, a repeller electrode 4, an ion funnel 7, a mass analyzer 8 and a vacuum module, wherein the ionization source cavity 3 is provided with a sample injection port, a vacuum exhaust port and an ion output port, the vacuum ultraviolet lamp 2, the repeller electrode 4 and the ion funnel 7 are sequentially arranged in the ionization source cavity 3 along the axial direction of the ion output port, and the ion funnel 7 is close to the ion output port, and the light emitted by the light source emitting end of the vacuum ultraviolet lamp 2 passes through the repeller electrode 4 and the ion funnel 7 in sequence, that is, the vacuum ultraviolet lamp 2 is located at the repeller electrode 4. 4 is located on the side away from the ion output port, and the ion funnel 7 is located on the side of the repeller electrode 4 close to the ion output port; the sampling module is arranged at the sampling port to transport the sample to be tested into the ion source cavity 3; the vacuum pumping module is arranged on the vacuum pumping port to vacuum the ion source cavity 3; the ion output port is externally connected to the mass analyzer 8; a DC voltage is applied to the repeller electrode 4, and a DC voltage and a radio frequency voltage are applied to the ion funnel 7; the sample is ionized under the action of the vacuum ultraviolet lamp 2, and the sample ions are focused and transmitted to the mass analyzer 8 under the action of the repeller electrode 4 and the ion funnel 7 to achieve final detection and analysis.

[0030] In an embodiment of the present invention, the injection module includes an injection capillary 1, a volatilization chamber 10 and a sample delivery tube 12, wherein an air inlet and an air outlet are respectively provided on opposite sides of the volatilization chamber 10, the air inlet is externally connected to a flow meter 9, and the flow meter 9 is used to control the flow rate of the carrier gas entering the volatilization chamber 10; the air outlet is tightly connected to one end of the sample delivery tube 12, and the other end of the sample delivery tube 12 is tightly connected to one end of the injection capillary 1 through a three-hole joint 13, and the other end of the injection capillary 1 is inserted into the ionization source cavity 3 through the injection port and extends to the space between the repeller electrode 4 and the ion funnel 7; the unused end of the three-hole joint 13 is used to remove the surplus carrier gas. The sample 11 to be tested is placed in the volatilization chamber 10, and the components to be tested generated by the sample 11 to be tested in the volatilization chamber 10 enter the ionization source cavity 3 through the sample delivery tube 12 and the injection capillary 1 under the carrier of the airflow.

[0031] Furthermore, the volatilization chamber 10, the sample delivery tube 12, the three-hole joint 13 and the injection capillary 1 are all wrapped by a heating device, and the temperature of the heating device can be adjusted between 0-200°C.

[0032] Specifically, the carrier gas flowing through the flow meter 9 is nitrogen or helium, the gas flow rate is 50-200 ml / min, and the carrier gas flow rate is greater than the injection amount of the injection capillary 1; the inner diameter of the sample delivery tube 12 is 3-6 mm, and the inner diameter of the injection capillary 1 is 100-250 μm. The sample delivery tube 12 adopts a polyfluoro tube. The volatilization chamber 10 is the volatilization area of ​​the sample to be tested 11, and the axial center line of the air inlet on the upper left side and the axial center line of the air outlet on the lower right side are both parallel to the horizontal plane.

[0033] In an embodiment of the present invention, the vacuum pumping module includes an air pressure valve 5 and a vacuum mechanical pump 6; the vacuum exhaust port of the ionization source cavity 3 is connected to the air pressure valve 5 and the vacuum mechanical pump 6 in sequence from the inside to the outside; the air pressure in the ionization source cavity 3 is between 10-1000Pa, which is jointly regulated by the air pressure valve 5 and the vacuum mechanical pump 6.

[0034] Specifically, the ionization source chamber 3 is a hollow cubic structure, with a circular vacuum pumping port and an ion output port respectively provided on the right side wall and the lower side wall, and a sample inlet provided in the middle of the left side wall.

[0035] See also Figure 1As shown, in an embodiment of the present invention, the ion funnel 7 includes a plurality of annular flat funnel electrodes which are arranged in parallel and at equal intervals and each have a circular through hole, the number of the annular flat funnel electrodes is N, and N is an even number. The aperture of the circular through hole of each annular flat funnel electrode decreases successively along the light emitting direction of the vacuum ultraviolet lamp 2. The DC voltage applied to the repeller electrode 4 and each annular flat funnel electrode in the ion funnel 7 decreases successively along the direction of the light emitting end of the vacuum ultraviolet lamp 2, and forms a DC gradient electric field, and the gradient electric field is 2-20V / cm. A radio frequency voltage is applied to each annular flat funnel electrode in the ion funnel 7, and the peak-to-peak amplitude of the radio frequency on any two adjacent annular flat funnel electrodes is equal and the phase is opposite. The radio frequency frequency of the radio frequency voltage is 0.5-5MHz, and the radio frequency peak-to-peak value is 10-800V.

[0036] Specifically, the repeller electrode 4 is an annular flat plate structure with a circular through hole in the middle; the thickness of the repeller electrode 4 is 2-4 mm, and the diameter of the circular through hole in the middle is 4-10 mm. The number of annular flat plate funnel electrodes in the ion funnel 7 is 22, and the thickness of each annular flat plate funnel electrode is consistent, all of which are 0.5-1 mm, and the diameter of the circular through hole in the middle is 1-20 mm. The center line of the circular through hole of the repeller electrode 4, the center line of the circular through holes of all the annular flat plate funnel electrodes of the ion funnel 7, the axial center line of the ion output port, and the axial center line of the light source emitting end of the vacuum ultraviolet lamp 2 are all collinear.

[0037] Furthermore, the materials of the repeller electrode 4 and each annular flat funnel electrode are conductive metal or a flat plate with a conductive metal layer plated on the surface. The vacuum ultraviolet lamp 2 is a low-pressure krypton lamp with a large light window diameter, and the photon emission diameter is 6-12 mm.

[0038] In the embodiment of the present invention, the mass analyzer 8 is a time-of-flight mass analyzer or an orbital trap mass analyzer with ultra-high resolution and time resolution of less than 1 s, which can meet the research needs of quickly tracking the dynamic changes of volatile substances.

[0039] Preferably, the axial centerline of the vacuum exhaust port of the ion source cavity 3 is parallel to the horizontal plane; the axial centerline of the ion output port of the ion source cavity 3 and the axial centerline of the light source emitting end of the vacuum ultraviolet lamp 2 are both perpendicular to the horizontal plane, and the air pressure in the ion source cavity 3 is 450 Pa. The DC voltage applied to the repeller electrode 4 and each annular flat funnel electrode of the ion funnel 7 is successively reduced along the direction of the light emitted from the light source emitting end of the vacuum ultraviolet lamp 2 and forms a DC gradient electric field, and the gradient electric field is 7.5V / cm; RF voltage is applied to each annular flat funnel electrode of the ion funnel 7, and the RF peak-to-peak amplitudes of any two adjacent funnel electrodes are equal and opposite in phase; the applied RF frequency is 0.98MHz, and the RF peak-to-peak value is 120V.

[0040] Preferably, the thickness of the repeller electrode 4 is 3 mm, and the diameter of the middle through hole is 8 mm; the thickness of each funnel electrode in the ion funnel 7 is consistent, which is 0.5 mm, and the diameter of the middle circular through hole is 2-18 mm; the repeller electrode 4 and each annular flat funnel electrode in the ion funnel 7 are made of stainless steel flat plates.

[0041] The volatilization chamber 10 is the volatilization area of ​​the sample 11 to be tested, and the axial center line of the air inlet and the axial center line of the air outlet are parallel to the horizontal plane. The carrier gas flowing through the flowmeter 9 is nitrogen, and the gas flow rate is 100ml / min, which is greater than the injection amount of the injection capillary 1. The inner diameter of the sample delivery tube 12 is 3mm, and the inner diameter of the injection capillary 1 is 250μm. The temperature of the volatilization chamber 10, the tetrafluoro tube 12, the three-hole joint 13 and the injection capillary 1 is set to 150℃. The photon emission diameter of the vacuum ultraviolet lamp 2 is 8mm. The mass analyzer 8 is a time-of-flight mass analyzer with ultra-high resolution and time resolution of less than 1s, which can meet the research needs of rapidly tracking the dynamic changes of volatile substances.

[0042] The photoionization source in the present invention combines an ion funnel with a photoionization source with a larger light-emitting area. Since the ion funnel has a good focusing effect, ions with a larger initial distribution area can be focused, thereby further improving the detection sensitivity to meet the detection needs of trace non-volatile organic pollutants.

[0043] Another embodiment of the present invention provides a method for real-time online analysis of non-volatile organic pollutants using the device in the above embodiment, the method comprising: placing a sample 11 to be tested in a volatilization chamber 10, setting a heating temperature, introducing a carrier gas with a fixed flow rate into the volatilization chamber 10 through a flowmeter 9, and the carrier gas carrying the volatile components of the sample 11 to be tested passes through a sample delivery tube 12, a three-hole joint 13 and an injection capillary 1 in sequence and then enters an ionization source cavity 3; the non-volatile components with a low content are first efficiently ionized under the action of a vacuum ultraviolet lamp 2 with a large photon emission diameter, and then the sample ions are effectively focused and transmitted to a mass analyzer 8 under the action of a repeller electrode 4 and an ion funnel 7 to achieve final detection and analysis.

[0044] Example

[0045] The device structure of the present invention is specifically referred to Figure 1 To build a simulation model using SIMION under the above conditions, see Figure 2, and simulate the ion transmission efficiency. The ion mass-to-charge ratio (m / z) used in the simulation is 116, the initial kinetic energy divergence is 0.5-2eV, the initial angle divergence is 60°, and the ion generation area is a cylindrical area whose axial centerline coincides with the centerline of the repeller electrode 4. The length of the cylindrical area is fixed at 10mm, and the midpoint is 6mm away from the lower surface of the repeller electrode 4. The upper and lower bottom diameters of the cylindrical area represent the photon emission diameter of the vacuum ultraviolet lamp 2. Assuming that the sample molecules are evenly distributed, the number of simulated ions is set to 100, 400, 900 and 1600 respectively according to the diameter of the ion generation cylindrical area of ​​2mm, 4mm, 6mm and 8mm. Please refer to the simulation results. Figure 3 , when the RF peak-to-peak value of the ion funnel 7 is 0V, the number of ions passing through is 7 when the photon emission diameter is 2mm, and its transmission efficiency is 7%; when the photon emission diameter is 8mm, the number of ions passing through is 25, and its transmission efficiency is 1.6%. It can be seen that in the absence of the focusing effect of the ion funnel 7, although the use of the vacuum ultraviolet lamp 2 with a large photon emission diameter will improve the sensitivity, the ion transmission efficiency is decreasing. When the RF peak-to-peak value of the ion funnel 7 is 120V, the number of ions passing through is 47 when the photon emission diameter is 2mm, and its transmission efficiency is 47%. Compared with the RF peak-to-peak value of the ion funnel 7 at 0V, the signal intensity is increased by 6.7 times, and the increase factor gradually increases with the increase of the photon emission diameter. When it reaches 8mm, the increase factor is 32.9 times, and the transmission efficiency at this time is 51.4%. It can be seen that combining the ion funnel with a photoionization source with a larger light-emitting area is a good means to further improve the detection sensitivity.

[0046] The present invention provides a device and method for real-time online analysis of non-volatile organic pollutants. It is based on ultra-high sensitive photoionization source mass spectrometry technology to achieve online analysis of non-volatile organic pollutants that may be contained in common items. The device mainly includes three parts: a volatilization chamber, an ultra-high sensitive photoionization source, and a mass analyzer. The components to be tested generated by the sample in the volatilization chamber pass through a tetrafluoro tube and an injection capillary in sequence under the airflow carrier and enter the photoionization source area for ionization; an ion funnel that can focus a wide range of ions is provided in the photoionization source, and the present invention uses a photoionization source with a larger light-emitting area to further improve the detection sensitivity; the focused ions are transmitted to the mass analyzer for detection. The device and method used in the present invention have a significant improvement in sensitivity, meeting the detection requirements for trace non-volatile organic pollutants, especially for substances such as phthalates and polycyclic aromatic hydrocarbons. It has a much better effect.

[0047] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A device for real-time online analysis of low-volatile organic pollutants, characterized in that: The invention comprises a sample injection module, a vacuum ultraviolet lamp (2), an ionization source cavity (3), a repeller electrode (4), an ion funnel (7), a mass analyzer (8) and a vacuum pumping module, wherein the ionization source cavity (3) is provided with a sample injection port, a vacuum pumping port and an ion output port, the vacuum ultraviolet lamp (2), the repeller electrode (4) and the ion funnel (7) are sequentially arranged in the ionization source cavity (3) along the axial direction of the ion output port, and the ion funnel (7) is close to the ion output port, and the light emitted by the light source emitting end of the vacuum ultraviolet lamp (2) passes through the repeller electrode (4) and the ion funnel (7) in sequence. 7); a sample injection module is arranged at the sample injection port, and conveys a sample to be tested into the ion source cavity (3); a vacuum pumping module is arranged at the vacuum pumping port, and is used for vacuum pumping the ion source cavity (3); the ion output port is externally connected to a mass analyzer (8); a DC voltage is applied to the repeller electrode (4), and a DC voltage and a radio frequency voltage are applied to the ion funnel (7); the sample is ionized under the action of the vacuum ultraviolet lamp (2), and the sample ions are focused and transmitted to the mass analyzer (8) under the action of the repeller electrode (4) and the ion funnel (7), so as to achieve final detection and analysis.

2. The device for real-time online analysis of low-volatile organic pollutants according to claim 1, characterized in that: The ion funnel (7) comprises a plurality of annular flat plate funnel electrodes which are arranged in parallel and at equal intervals and each have a circular through hole, and the aperture of the circular through hole of each annular flat plate funnel electrode decreases in sequence along the light emitting direction of the vacuum ultraviolet lamp (2).

3. The device for real-time online analysis of low-volatile organic pollutants according to claim 2, characterized in that: The DC voltage applied to the repeller electrode (4) and each annular flat funnel electrode in the ion funnel (7) is sequentially reduced along the direction of light emitted from the light source end of the vacuum ultraviolet lamp (2) to form a DC gradient electric field; A radio frequency voltage is applied to each annular flat funnel electrode in the ion funnel (7), and the radio frequency peak-to-peak amplitudes of any two adjacent annular flat funnel electrodes are equal and the phases are opposite.

4. The device for real-time online analysis of low-volatile organic pollutants according to claim 3, characterized in that: The gradient electric field of the DC gradient electric field is 2-20 V / cm; the radio frequency frequency of the radio frequency voltage is 0.5-5 MHz, and the radio frequency peak-to-peak value is 10-800 V; the number of the annular flat funnel electrodes is N, and N is an even number.

5. The device for real-time online analysis of low-volatile organic pollutants according to claim 2, characterized in that: The repelling electrode (4) is an annular flat plate structure with a circular through hole in the middle; the thickness of the repelling electrode (4) is 2-4 mm, and the diameter of the circular through hole in the middle is 4-10 mm; The thickness of each annular flat plate funnel electrode in the ion funnel (7) is 0.5-1 mm, and the diameter of the circular through hole in the middle thereof is 1-20 mm; The material of the repeller electrode (4) and each of the annular flat plate funnel electrodes is a conductive metal or a flat plate with a conductive metal layer plated on the surface.

6. The device for real-time online analysis of low-volatile organic pollutants according to claim 2, characterized in that: The vacuum ultraviolet lamp (2) is a low-pressure krypton lamp with a large light window diameter, and the photon emission diameter is 6-12 mm.

7. The device for real-time online analysis of low-volatile organic pollutants according to claim 2, characterized in that: The injection module comprises an injection capillary (1), a volatilization chamber (10) and a sample delivery tube (12), wherein an air inlet and an air outlet are respectively arranged on both sides of the volatilization chamber (10), the air inlet is externally connected to a flow meter (9), and the flow meter (9) is used to control the flow rate of the carrier gas entering the volatilization chamber (10); the air outlet is tightly connected to one end of the sample delivery tube (12), the other end of the sample delivery tube (12) is tightly connected to one end of the injection capillary (1) through a three-hole joint (13), the other end of the injection capillary (1) penetrates from the injection port into the ionization source cavity (3) and extends to the space between the repeller electrode (4) and the ion funnel (7); the sample (11) to be tested is placed in the volatilization chamber (10). The volatilization chamber (10), the sample delivery tube (12), the three-hole joint (13) and the injection capillary (1) are all wrapped by a heating device, and the temperature of the heating device can be adjusted between 0-200°C.

8. The device for real-time online analysis of low-volatile organic pollutants according to claim 7, characterized in that: The carrier gas flowing through the flow meter (9) is nitrogen or helium, the gas flow rate is 50-200 ml / min, and the carrier gas flow rate is greater than the injection volume of the injection capillary (1); The inner diameter of the sample delivery tube (12) is 3-6 mm, and the inner diameter of the injection capillary (1) is 100-250 μm.

9. The device for real-time online analysis of low-volatile organic pollutants according to claim 1, characterized in that: The vacuum pumping module comprises an air pressure valve (5) and a vacuum mechanical pump (6); the vacuum pumping port of the ionization source cavity (3) is connected to the air pressure valve (5) and the vacuum mechanical pump (6) in sequence from the inside to the outside; The air pressure in the ionization source cavity (3) is between 10 and 1000 Pa and is adjusted by the air pressure valve (5) and the vacuum mechanical pump (6).

10. A method for real-time online analysis of low-volatile organic pollutants using the device as claimed in claim 8, characterized in that: A sample to be tested (11) is placed in a volatilization chamber (10), and a heating temperature is set. A carrier gas with a fixed flow rate is introduced into the volatilization chamber (10) through a flow meter (9). The carrier gas carries the volatile components of the sample to be tested (11) and passes through a sample delivery tube (12), a three-hole joint (13) and a sampling capillary (1) in sequence before entering an ionization source chamber (3). The low-content, non-volatile components are firstly ionized efficiently under the action of a vacuum ultraviolet lamp (2) having a large photon emission diameter. Then, the sample ions are effectively focused under the action of a repeller electrode (4) and an ion funnel (7) and transmitted to a mass analyzer (8) for final detection and analysis.

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