Thermal cracking sample injector with sample recycling and reinjection and pollution isolation functions

Abstract

The invention provides a thermal cracking sample injector with sample recycling and reinjection and pollution isolation functions, one end of a thermal cracking carrier gas circuit is connected with an external gas source, and the other end of the thermal cracking carrier gas circuit is sequentially connected with a thermal cracking carrier gas electromagnetic valve and a thermal cracking carrier gas pressure controller, is finally connected to a thermal cracking sample injector main body, and is communicated with an upper opening of a thermal cracking cavity; a lower opening of the thermal cracking cavity is communicated with a first interface of the three-way interface; a second interface of the three-way interface is connected with a thermal cracking shunting gas circuit, the thermal cracking shunting gas circuit is further bypassed with a recovery pipeline, the thermal cracking shunting gas circuit is used for emptying, and the recovery pipeline is used for recovering and sampling; a third interface of the three-way interface is connected with a thermal cracking sample injection needle, and the thermal cracking sample injection needle is inserted into a gas chromatographic sample injection port provided with a gas chromatographic column; and the gas chromatography sample inlet is also communicated with a gas chromatography carrier gas path and a gas chromatography split-flow gas path.

Description

Technical Field

[0001] The present invention relates to an injector used in gas chromatography, mass spectrometry and related fields, and particularly relates to a pyrolysis injector. Background Art

[0002] Pyrolysis is an injection device applied in the fields of gas chromatography and mass spectrometry analysis. Its main function is to pyrolyze solid samples into gasified small molecule compounds through instantaneous high temperature and introduce them into subsequent analytical equipment such as gas chromatography or mass spectrometry. Pyrolysis injectors are widely used in fields such as polymer materials, environmental detection, biomedicine, catalysis, and petrochemical industry.

[0003] Pyrolysis injectors mainly test the composition and additive components of solid samples. Since the substance concentration of solid samples is the highest among the three states of gas, liquid, and solid, in order to avoid the contamination and signal overload of the subsequent analytical equipment caused by the relatively high concentration of products generated by the pyrolysis of solid samples, generally a small amount of sample is taken for on-machine analysis, such as milligram level, or even lower microgram level sample loading. However, the additive components in the gas products generated by pyrolysis, as well as the pyrolysis products of some main components, have extremely low concentrations at such milligram / microgram level sample loading, resulting in the inability of the subsequent analytical equipment to detect and analyze them. Therefore, it is difficult to achieve a balance between sample matrix contamination and the detection of low-content target substances. Currently, the pyrolysis equipment on the market cannot solve this contradiction. At the same time, since pyrolysis is a destructive injection, for some scarce samples, such as forensic samples, they are consumed after one analysis. Since the samples cannot be obtained again, they cannot be re-tested and confirmed.

[0004] As described in the patent CN210711399U, that is, the traditional pyrolysis injection method is adopted, borrowing the functions of gas chromatography carrier gas and split control to achieve the injection and splitting of pyrolysis. During the injection process of the pyrolysis products of the sample, a part is introduced into analytical equipment such as gas chromatography-mass spectrometry, and a part is vented through the split port of the gas chromatography. This traditional pyrolysis injection method cannot provide a suitable solution in terms of the analysis sensitivity of low-concentration pyrolysis products and the re-analysis and confirmation of samples. At the same time, as described in the split injection system of the patent CN214252163U, its split pipeline of the injection system is set up to achieve two-stage splitting, reducing the injection volume and system contamination. However, its split part does not have a heating and heat preservation device, which is prone to sample condensation and blockage. And its pyrolysis temperature range is relatively narrow, only reaching 450°C, and it can only achieve the function of thermal desorption, not reaching the high temperature required for pyrolysis, and cannot process solid samples and samples that require high-temperature pyrolysis for analysis. It also does not have a rapid cooling module. When the instrument needs to cool down during the analysis interval, it can only wait for natural cooling for a long time.

[0005] The pyrolysis involved in the present invention is vertical pyrolysis, which is generally installed above a gas chromatography injection port. The pyrolysis products are directly introduced into the gas chromatography or mass spectrometry through a sampling needle for analysis. After the sample introduction is completed or after long-term sample analysis, it is generally necessary to perform high-temperature cleaning on the pyrolyzer to remove residual contaminants in the pyrolysis chamber. During the high-temperature cleaning of the pyrolyzer, since the pyrolyzer borrows the carrier gas path of the gas chromatography injection port and is installed above the gas chromatography injection port, the residual contaminants discharged at high temperature will also directly enter the subsequent gas chromatography and other analytical equipment through the pyrolysis sampling needle, causing further contamination. This is also the general situation during the high-temperature cleaning of existing vertical pyrolysis injectors at present. Summary of the Invention

[0006] The main object of the present invention is to solve the sensitivity problem of pyrolysis for the analysis of low-concentration samples, add the functions of sample recovery, preservation, and re-injection analysis, and the pollution isolation function between the pyrolysis injector and the subsequent analytical equipment during high-temperature cleaning.

[0007] The technical means adopted by the present invention are as follows:

[0008] A pyrolysis injector with functions of sample recovery, re-injection, and pollution isolation, characterized by comprising:

[0009] One end of the pyrolysis carrier gas path is connected to an external gas source, and the other end is successively connected to a pyrolysis carrier gas solenoid valve, a pyrolysis carrier gas pressure controller, and finally connected to the pyrolysis injector main body and communicated with the upper opening of the pyrolysis chamber;

[0010] The lower opening of the pyrolysis chamber is communicated with the first interface of a three-way interface;

[0011] The second interface of the three-way interface is connected to a pyrolysis shunt gas path, and a recovery pipeline is bypassed on the pyrolysis shunt gas path. A pyrolysis vent filter, a pyrolysis vent solenoid valve, and a pyrolysis vent flow controller are successively arranged on the pyrolysis shunt gas path. A pyrolysis recovery solenoid valve, a pyrolysis recovery sampling tube, a pyrolysis recovery flow controller, and a recovery sampling pump are successively arranged on the recovery pipeline;

[0012] The third interface of the three-way interface is connected to a pyrolysis sampling needle, and the pyrolysis sampling needle is inserted into a gas chromatography injection port equipped with a gas chromatography column; wherein, the gas chromatography injection port is also communicated with a gas chromatography carrier gas path and a gas chromatography shunt gas path.

[0013] In the pyrolysis injector with functions of sample recovery, re-injection, and pollution isolation, the pyrolysis chamber is arranged inside the pyrolysis injector main body, and a pyrolysis heating module, a pyrolysis cooling module, and a pyrolysis heat preservation module are arranged outside the pyrolysis chamber.

[0014] The pyrolysis injector with the functions of sample recovery, re-injection and pollution isolation, wherein the pyrolysis chamber is capable of adapting to a metal sample cup and the pyrolysis recovery sampling tube.

[0015] The pyrolysis injector with the functions of sample recovery, re-injection and pollution isolation, wherein the three-way interface is equipped with a heating module.

[0016] Technical effects of the present invention:

[0017] 1. The quartz pyrolysis chamber of the present invention has a larger capacity than the injectors on the market, and the pyrolysis temperature can reach 1100 °C. It can not only rapidly pyrolyze samples, but also pyrolyze and inject large-volume samples.

[0018] 2. The present invention has a sample recovery function. Through the setting of the recovery and vent air paths of pyrolysis, the pyrolysis products are recovered and enriched in the pyrolysis recovery sampling tube with packing, thereby improving the analysis sensitivity of low-concentration target substances in the pyrolysis products, and at the same time realizing the recovery, preservation and secondary analysis of samples.

[0019] 3. The three-way interface of the present invention has a heating module for the pyrolysis three-way interface, which can ensure that the sample will not condense during the processes of recovery, venting and injection.

[0020] 4. The present invention is provided with a switching solenoid valve on the recovery pipeline, which can select whether to recover the sample or not.

[0021] 5. The pyrolysis recovery sampling tube of the present invention is a standard thermal desorption sampling tube made of metal or glass with an outer diameter of 1 / 4 inch and a length of 3.5 inches, and can be adapted to the pyrolysis chamber.

[0022] 6. The present invention is provided with a recovery flow controller on the recovery pipeline, which can quantitatively recover the volume of gas to achieve the purpose of quantitative analysis.

[0023] 7. The quartz pyrolysis chamber of the present invention is adapted to the pyrolysis sample cup and the pyrolysis recovery sampling tube, and can realize the pyrolysis injection and the thermal desorption injection of the sampling tube after recovery by using a set of pyrolysis injectors.

[0024] 8. The set pyrolysis vent air path can effectively reduce the pyrolysis products entering the pyrolysis injection needle, thereby reducing the risk of blockage of the pyrolysis injection needle.

[0025] 9. The present invention is provided with a filter on the pyrolysis vent air path, which can effectively prevent the pollution of the sample gas to the air.

[0026] 10. The present invention has a larger sample loading range. Through the recovery and vent air paths of pyrolysis and the splitting of gas chromatography, a larger range of sample splitting and venting control is realized, so as to adapt to a larger sample injection volume and reduce the pollution to the system.

[0027] 11. After the thermal cracking, the sample of the present invention is directly introduced into the gas chromatograph through the thermal cracking injection needle without a sample transmission pipeline in the middle, thus reducing the sample transmission process and effectively solving the pollution residue in the sample gas transmission process.

[0028] 12. The present invention can effectively isolate pollutants from entering the back-end analysis equipment during pyrolysis high-temperature cleaning by simply adjusting the balance between the pyrolysis carrier gas pressure and the gas chromatography carrier gas pressure.

[0029] 13. The present invention is provided with a thermal cracking cooling module, which has a rapid cooling function. It can quickly adjust from a high temperature state to a medium temperature or a low temperature state, thereby improving work efficiency without waiting for natural cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the thermal cracking structure of the present invention;

[0031] Figure 2 When no pollution isolation is performed, the pollutants generated by pyrolysis high-temperature cleaning enter the spectrum of the analytical equipment;

[0032] Figure 3 After thermal pyrolysis and gas chromatography carrier gas pressure isolation, the pollutants produced by thermal pyrolysis high temperature cleaning do not enter the spectrum of the analytical equipment.

[0033] Explanation of the accompanying drawings: 1-thermal pyrolysis injector body; 11-thermal pyrolysis chamber; 12-thermal pyrolysis heating module; 13-thermal pyrolysis cooling module; 14-thermal pyrolysis insulation module; 15-metal sample cup; 2-thermal pyrolysis carrier gas path; 21-thermal pyrolysis carrier gas solenoid valve; 22-thermal pyrolysis carrier gas pressure controller; 3-three-way interface; 31-thermal pyrolysis three-way interface heating module; 4-thermal pyrolysis diversion gas path; 41-thermal pyrolysis vent filter; 42-thermal pyrolysis vent solenoid valve; 43-thermal pyrolysis vent flow controller; 44-thermal pyrolysis recovery solenoid valve; 45-thermal pyrolysis recovery sampling tube; 46-thermal pyrolysis recovery flow controller; 47-recovery sampling pump; 5-thermal pyrolysis injection needle; 6-gas chromatograph injection port; 61-gas chromatograph carrier gas path; 62-gas chromatograph diversion gas path; 7-gas chromatograph column. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] likeFigure 1 As shown, it is a preferred embodiment of a pyrolysis injector provided by the present invention with functions of sample recovery and reinjection and contamination isolation, where:

[0036] One end of the pyrolysis carrier gas path 2 is connected to an external gas source through a gas pipeline, and the pipeline at the other end is successively connected to a pyrolysis carrier gas solenoid valve 21 and a pyrolysis carrier gas pressure controller 22, and finally connected to the pyrolysis injector body 1; inside the pyrolysis injector body 1, there is a pyrolysis chamber 11, and outside the pyrolysis chamber 11, there are arranged a pyrolysis heating module 12, a pyrolysis cooling module 13 and a pyrolysis heat preservation module 14; the pyrolysis chamber 11 can provide a high-temperature environment with a maximum temperature of up to 1100 °C for sample pyrolysis;

[0037] The other end of the pyrolysis carrier gas path 2 is communicated with the upper opening of the pyrolysis chamber 11. The pyrolysis chamber 11 can be adapted to a metal sample cup 15 of a conventional specification and the following pyrolysis recovery sampling tube 45. The lower opening of the pyrolysis chamber 11 is communicated with the first interface of a three-way interface 3; among them, the three-way interface 3 is equipped with a heating module 31;

[0038] The second interface of the three-way interface 3 is connected to a pyrolysis split gas path 4. A recovery pipeline is also bypassed on the pyrolysis split gas path 4. On the pyrolysis split gas path 4, there are successively arranged a pyrolysis vent filter 41, a pyrolysis vent solenoid valve 42 and a pyrolysis vent flow controller 43. On the recovery pipeline, there are successively arranged a pyrolysis recovery solenoid valve 44, a pyrolysis recovery sampling tube 45, a pyrolysis recovery flow controller 46 and a recovery sampling pump 47;

[0039] The third interface of the three-way interface 3 is connected to a pyrolysis injection needle 5, and the pyrolysis injection needle 5 is inserted into a gas chromatography injection port 6 equipped with a gas chromatography column 7, so as to realize pyrolysis injection into a backend analysis device such as a gas chromatography - mass spectrometry;

[0040] Among them, the gas chromatography injection port 6 is also communicated with a gas chromatography carrier gas path 61 and a gas chromatography split gas path 62.

[0041] The following is an explanation of its working process:

[0042] 1. During sample testing:

[0043] The pyrolysis carrier gas solenoid valve 21 is opened, and the pressure of the carrier gas introduced is controlled by the pyrolysis carrier gas pressure controller 22. This pressure is adjusted to be higher than the pressure of the gas chromatography carrier gas path 61, such as 60 kPa or above;

[0044] The pyrolysis carrier gas enters the pyrolysis chamber 11 set at a high temperature. The sample placed in the metal sample cup 15 undergoes a pyrolysis reaction and generates vaporized pyrolysis products. The pyrolysis carrier gas takes the pyrolysis products out of the pyrolysis chamber 11 and enters the three-way interface 3;

[0045] In the three-way interface 3 with a heating module 31, the pyrolysis carrier gas and pyrolysis products are divided into three parts:

[0046] The first part of the gas is controlled by the pyrolysis vent solenoid valve 42 and the pyrolysis vent flow controller 43, with a flow range from 0 ml / min to 1000 ml / min, and finally vented. To avoid contaminating the environment with harmful substances in the pyrolysis products, the gas will first pass through the pyrolysis vent filter 41 to adsorb and remove the pyrolysis products before entering the pyrolysis vent solenoid valve 42;

[0047] The second part of the gas is controlled by the pyrolysis recovery solenoid valve 44 for recovery. If recovery is required, it will sequentially pass through the pyrolysis recovery solenoid valve 44, the pyrolysis recovery sampling tube 45, the pyrolysis recovery flow controller 46, and the sampling pump 47, and be quantitatively recovered and enriched in the pyrolysis recovery sampling tube 45;

[0048] The last part of the pyrolysis carrier gas and pyrolysis products passes through the gas path three-way interface 3, enters the pyrolysis injection needle 5, and is introduced into the gas chromatography injection port 6. In the gas chromatography injection port 6, the carrier gas in the gas chromatography carrier gas path 61 will introduce the pyrolysis carrier gas and pyrolysis products into the gas chromatography split gas path 62 and the gas chromatography column 7 respectively, completing the pyrolysis injection analysis.

[0049] During this test process, by adjusting the pyrolysis recovery solenoid valve 44 and the pyrolysis recovery flow controller 46, the pyrolysis product gas is quantitatively recovered and enriched. The recovered sampling tube 45 can use this pyrolysis injector for secondary desorption injection. Since sample enrichment is carried out during the recovery process, high-sensitivity detection of low-concentration target substances in the pyrolysis products can be achieved. The pyrolysis recovery sampling tube 45 also realizes the recovery and preservation of the pyrolysis products of the sample, and secondary analysis tests and result confirmation can be carried out on it.

[0050] During this test process, the pyrolysis split gas path 4 performs an independent vent operation on the pyrolysis product gas through the pyrolysis vent solenoid valve 42 and the pyrolysis vent flow controller 43. Combined with the backend gas chromatography split gas path 62, a wider range of split control is achieved, so as to adapt to a larger sample loading range and reduce system contamination.

[0051] 2. High-temperature cleaning of pyrolysis:

[0052] The pyrolysis carrier gas solenoid valve 21 is opened, and the pressure of the carrier gas introduced is controlled by the pyrolysis carrier gas pressure controller 22. This pressure is adjusted to be higher than the pressure of the gas chromatography carrier gas path 61, such as 40 - 50 kPa;

[0053] The pyrolysis carrier gas enters the pyrolysis chamber 11 set at a high temperature. The high temperature vaporizes the pollutants in the pyrolysis chamber 11, and the pyrolysis carrier gas carries the vaporized pollutants out and into the three-way interface 3. Under the pressure balance damping of the gas chromatography carrier gas circuit 61, the pyrolysis carrier gas and the vaporized pollutants cannot enter the gas chromatography injection port 6, and can only pass through the pyrolysis vent filter 41 of the pyrolysis split gas path 4 and flow out and vent through the open pyrolysis vent solenoid valve 42 and the pyrolysis vent flow controller 43.

[0054] During this cleaning process, the pollutants baked by high-temperature pyrolysis cleaning will be directly discharged from the outlet of the pyrolysis split gas path 4, avoiding the pollution of the back-end analysis equipment such as the gas chromatography injection port 6.

[0055] Such as Figure 2 And Figure 3 As shown, they are respectively the spectrograms of the pollutants generated by high-temperature pyrolysis cleaning entering the gas chromatography - mass spectrometry without being isolated, and the spectrograms of the pollutants generated by high-temperature cleaning not entering the gas chromatography - mass spectrometry after the pressure balance isolation between pyrolysis and gas chromatography. The results show that through the pressure balance between pyrolysis and gas chromatography, there is a significant pollution isolation effect.

[0056] Among them, during the testing process or the cleaning process, the different working temperatures of the pyrolysis chamber 11 can be quickly switched by controlling the pyrolysis heating module 12 and / or the pyrolysis cooling module 13. The temperature switching range is from 25°C to 1100°C. Therefore, it is not necessary to wait for natural cooling at a high temperature and then conduct sample testing at the next temperature.

[0057] Rapid cooling - When the pyrolysis or thermal desorption work is completed and it is necessary to quickly carry out the pyrolysis or thermal desorption work at a lower working temperature than the previous stage, this pyrolysis injector will automatically start the pyrolysis cooling module 13 for rapid cooling operation to improve the switching efficiency of working at different temperatures.

[0058] Rapid heating - When high-temperature pyrolysis is required, control the pyrolysis heating module 12 to quickly reach the high-temperature working state.

Claims

1. A pyrolysis injector with the functions of sample recovery and re-injection and contamination isolation, characterized in that, Comprising: One end of the pyrolysis carrier gas circuit is connected to an external gas source, and the other end is sequentially connected to a pyrolysis carrier gas solenoid valve, a pyrolysis carrier gas pressure controller, and finally connected to the pyrolysis injector body and communicated with the upper opening of the pyrolysis chamber; The lower opening of the pyrolysis chamber is communicated with the first interface of the three-way interface; The second interface of the three-way interface is connected to the pyrolysis split gas circuit, and a recovery pipeline is also bypassed on the pyrolysis split gas circuit. A pyrolysis vent filter, a pyrolysis vent solenoid valve, and a pyrolysis vent flow controller are sequentially arranged on the pyrolysis split gas circuit. A pyrolysis recovery solenoid valve, a pyrolysis recovery sampling tube, a pyrolysis recovery flow controller, and a recovery sampling pump are sequentially arranged on the recovery pipeline; The third interface of the three-way interface is connected to the pyrolysis injection needle, and the pyrolysis injection needle is inserted into the gas chromatography injection port equipped with a gas chromatography column; wherein, the gas chromatography injection port is also communicated with a gas chromatography carrier gas circuit and a gas chromatography split gas circuit.

2. The pyrolysis injector with sample recovery and reinjection and contamination isolation functions according to claim 1, wherein, The pyrolysis chamber is arranged inside the pyrolysis injector body, and a pyrolysis heating module, a pyrolysis cooling module, and a pyrolysis heat preservation module are arranged outside the pyrolysis chamber.

3. The pyrolysis injector with the functions of sample recovery and reinjection and contamination isolation according to claim 1, characterized in that, The pyrolysis chamber can be adapted to a metal sample cup and the pyrolysis recovery sampling tube.

4. The pyrolysis injector with the functions of sample recovery and reinjection and contamination isolation according to claim 1, wherein, The three-way interface is equipped with a heating module.

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