A dual chromatography column backflush system and method
Patent Information
- Application Number
- CN202611300462.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-26
- Publication Date
- 2026-10-20
AI Technical Summary
而对于样品气体中的挥发性有机物（VOCs）较少涉及，但是存在于气体样品中的少量VOCs会随气体样品进入毛细管色谱柱和稳定同位素质谱仪并逐渐累积，造成本底值不断增加，影响样品准确测定
[0026]本发明通过气动八通阀的一个接口经限流石英毛细管连接第一气动六通阀，在反吹状态下，气动八通阀的高纯氦气经限流石英毛细管进入第一气动六通阀并导入第二毛细管色谱柱，限流石英毛细管限制载气流量，使第二毛细管色谱柱在反吹期间持续获得稳定载气流，保证目标化合物气体与杂质气体的分离不中断，避免了现有技术中吸附柱烘烤再生需停止测样的问题，提高了分析效率。
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of chromatographic analysis technology, and specifically relates to a dual-column backflushing system and method. Background Technology
[0002] The accurate determination of nitrogen and oxygen isotope ratios of nitrate, nitrite, ammonia nitrogen, dissolved organic nitrogen isotopes, and N2O gas in water using the PreCon-GasBench-Restable Isotope Ratio Mass Spectrometer (IRMS) is of great significance for nitrogen cycle research.
[0003] Nitrate, nitrite, ammonia nitrogen, and dissolved organic nitrogen isotopes in water are typically converted into N2O gas through bacterial denitrification or chemical methods. Afterward, they are purified by purging and trapping using a micro-gas pre-concentration device, and then introduced into a stable isotope ratio mass spectrometer for analysis using a multifunctional gas preparation and introduction system. Currently, common methods for removing impurities from nitrate, nitrite, ammonia nitrogen, and dissolved organic nitrogen isotopes in water samples include: filling chemical traps with dehydrating agents (magnesium perchlorate or P2O5) to remove water vapor; using Nafion drying tubes to remove water; and filling with chemical reagents for CO2 removal (sodium bicarbonate, NaOH) to remove CO2. Volatile organic compounds (VOCs) in sample gases are less frequently addressed. However, small amounts of VOCs present in gaseous samples can enter the capillary column and stable isotope mass spectrometer along with the gas sample and gradually accumulate, causing a continuous increase in background values and affecting the accurate determination of the sample.
[0004] Based on the above problems, the common approach is to add a VOCs adsorption column. However, the existing method has the following drawbacks: the sample needs to be stopped during baking, which reduces the sample efficiency, and it cannot completely remove VOCs from the sample gas. Therefore, it does not completely solve the problem of VOCs contamination of the chromatographic column and isotope mass spectrometer.
[0005] In the field of gas chromatography / mass spectrometry (GC / MS), column backflushing is an effective method to reduce column and mass spectrometry contamination. It effectively separates components by utilizing the different retention times of each component in the column, with heavily contaminating components removed by backflushing the latter half of the column. In the analysis of nitrates, nitrites, ammonia nitrogen, and dissolved organic nitrogen isotopes, VOCs impurities have longer retention times than the analyte gas N₂O, which can be addressed through column backflushing. However, most existing column backflushing solutions are designed for general-purpose GC-MS systems, and there is currently no dual-column backflushing solution specifically for multifunctional gas preparation and introduction systems—such as stable isotope ratio mass spectrometers.
[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0007] To address or at least alleviate one or more of the above problems, a dual-column backflushing system and method are provided. This system can achieve backflushing of the first column while retaining the original functions of the instrument, effectively removing impurities such as VOCs from the sample, reducing instrument background, improving the stability of test results, reducing instrument wear and tear, and increasing sample testing efficiency.
[0008] To achieve the above objectives, according to a first aspect of the present invention, a dual-column backflush system is provided, comprising:
[0009] The pneumatic eight-way valve has one port connected to the first pneumatic six-way valve via a flow-limiting quartz capillary tube, and the other port connected to a helium source.
[0010] The first pneumatic six-way valve has one port connected to the second pneumatic six-way valve via a stainless steel connecting pipe, and the other port connected to the inlet of the second capillary chromatographic column.
[0011] The second pneumatic six-way valve has two ports connected to the two ends of the first capillary chromatographic column, and one port connected to the carrier gas to carry the sample gas.
[0012] By switching the first pneumatic six-way valve and the second pneumatic six-way valve, the carrier gas carries the sample gas through the first capillary column and the second capillary column for component separation, and the gas flow direction in the first capillary column is reversed to remove impurities.
[0013] Furthermore, the pneumatic eight-way valve has a first interface to an eighth interface; the first interface is connected to a helium source, the second interface is a second exhaust port, the third interface is connected to one end of a metering ring, the fourth interface is connected to the first pneumatic six-way valve through the flow-limiting quartz capillary, the fifth interface is connected to a helium source, the sixth interface is connected to the other end of the metering ring, and the eighth interface is a first exhaust port.
[0014] Furthermore, the first pneumatic six-way valve has a first port to a sixth port; the first port is connected to the fourth interface through the flow-limiting quartz capillary, the second port is the fourth exhaust port, the third port is unused, the fourth port is the fifth exhaust port, the fifth port is connected to the second pneumatic six-way valve through the stainless steel connecting pipe, and the sixth port is connected to the inlet of the second capillary chromatographic column.
[0015] Furthermore, the second pneumatic six-way valve has a first port to a sixth port; the first port is connected to one end of the first capillary column, the second port is connected to a helium source, the third port is a third exhaust port, the fourth port is connected to the other end of the first capillary column, the fifth port is connected to a carrier gas to carry the sample gas, and the sixth port is connected to the fifth port through the stainless steel connecting pipe.
[0016] Furthermore, both the first capillary column and the second capillary column are placed inside a column oven; both the first capillary column and the second capillary column are Rt-Q-BOND fused silica PLOT columns, with a column length of 15m and an inner diameter of 0.32mm; the flow-limiting quartz capillary has an outer diameter of 220μm, an inner diameter of 150μm, and a length of 1m; the stainless steel connecting tube is a 1 / 16-inch stainless steel tube.
[0017] To achieve the above objectives, according to a second aspect of the present invention, a method for performing dual-column backflushing using the above-described system is provided, comprising the following steps:
[0018] S1. In the injection state, switch the second pneumatic six-way valve and the first pneumatic six-way valve to the injection position, so that the first capillary column and the second capillary column are connected in series, and the carrier gas carries the sample gas through the first capillary column and the second capillary column in sequence for component separation.
[0019] S2. In the backflush state, switch the first pneumatic six-way valve and the second pneumatic six-way valve to the backflush position to reverse the gas flow in the first capillary column and discharge the volatile organic impurities retained in the first capillary column in the reverse direction.
[0020] Further, in the injection state, the second pneumatic six-way valve and the first pneumatic six-way valve are switched to the injection position, so that the first capillary column and the second capillary column are connected in series. The carrier gas carrying the sample gas passes through the first capillary column and the second capillary column in sequence for component separation, including:
[0021] Switch the second pneumatic six-way valve and the first pneumatic six-way valve to the injection position. The carrier gas carrying the sample gas enters through the fifth port, and then sequentially enters the first capillary column through the fourth port to separate the target compound gas and impurity gas. After that, it enters the fifth port through the first port, the sixth port, and the stainless steel connecting tube, and then enters the second capillary column through the sixth port for further separation of the target compound gas and impurity gas.
[0022] Furthermore, in the backflushing state, the first pneumatic six-way valve and the second pneumatic six-way valve are switched to the backflushing position, causing the gas flow in the first capillary column to reverse, thereby discharging the volatile organic impurities retained in the first capillary column in the reverse direction, including:
[0023] When the first and second pneumatic six-way valves are simultaneously switched to the backflush position, the high-purity helium gas from the fifth port enters the second capillary column sequentially through the fourth port, the flow-limiting quartz capillary, the first port, and the sixth port to continue the separation of the target compound gas from the impurity gas. At the same time, the high-purity helium gas from the second port enters the first capillary column and flows out from the third port, backflushing out the volatile organic impurities retained in the first capillary column.
[0024] Furthermore, it also includes: placing the first capillary column and the second capillary column in a column oven, and aging and removing impurities from the first capillary column and the second capillary column by heating in the column oven.
[0025] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:
[0026] This invention connects a first pneumatic six-way valve to one port of a pneumatic eight-way valve via a flow-limiting quartz capillary. In backflushing mode, high-purity helium gas from the pneumatic eight-way valve enters the first pneumatic six-way valve through the flow-limiting quartz capillary and is introduced into the second capillary chromatographic column. The flow-limiting quartz capillary restricts the carrier gas flow rate, ensuring that the second capillary chromatographic column continuously receives a stable carrier gas flow during backflushing. This guarantees uninterrupted separation of the target compound gas from the impurity gas, avoiding the problem of having to stop the sample analysis during the baking and regeneration of the adsorption column in the prior art, and improving analytical efficiency.
[0027] This invention connects the two ports of a second pneumatic six-way valve to both ends of a first capillary column. During backflushing, the second pneumatic six-way valve switches to reverse the gas flow direction in the first capillary column. High-purity helium gas enters the first capillary column from the second port of the second pneumatic six-way valve, carrying the retained volatile organic compound impurities out from the third port. This backflushing removes VOCs impurities online. Compared to the passive adsorption method of VOCs adsorption columns in the prior art, backflushing removes impurities more thoroughly, significantly reduces contamination of the column tip and ion source, extends the service life of the column and ion source, and improves detection stability.
[0028] This invention connects the sample to the pre-concentration device through the fifth port of the second pneumatic six-way valve and the sixth port to the fifth port of the first pneumatic six-way valve via a stainless steel connecting pipe. In the sample injection state, the two valves work together to connect the first capillary column and the second capillary column in series. The sample gas is first initially separated by the first column and then separated a second time by the second column. The two-stage series separation improves the separation degree between the target compound gas N2O and the impurity gas CO2, which is beneficial to improving the accuracy of isotope ratio determination.
[0029] This invention connects a pneumatic control module to a first pneumatic six-way valve and a second pneumatic six-way valve, and uses software to automatically control the two six-way valves to switch between the sample injection position and the backflush position, realizing the full automation of the sample injection-separation-backflush-impurity removal process without manual intervention. It is easy to operate and suitable for high-throughput analysis of batch samples.
[0030] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description
[0031] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments; those skilled in the art can obtain other drawings based on these drawings without any creative effort.
[0032] In the attached diagram:
[0033] Figure 1 This is a schematic diagram of the gas path for the sample injection state of the dual-column backflush system in this specific embodiment;
[0034] Figure 2 This is a schematic diagram of the backflushing gas path of the dual-column backflushing system in this specific embodiment;
[0035] Figure 3 This is a schematic diagram of the dual-column backflushing method in this specific embodiment.
[0036] Explanation of reference numerals in the attached figures:
[0037] 100. Pneumatic 8-way valve; 110. First port; 120. Second port; 130. Third port; 140. Fourth port; 150. Fifth port; 160. Sixth port; 170. Seventh port; 180. Eighth port;
[0038] 200. Flow-limiting quartz capillary tube;
[0039] 300, First pneumatic six-way valve; 310, First port; 320, Second port; 330, Third port; 340, Fourth port; 350, Fifth port; 360, Sixth port;
[0040] 400, First capillary column;
[0041] 500, Second capillary column;
[0042] 600. Exhaust pipe;
[0043] 700, Second pneumatic six-way valve; 710, First port; 720, Second port; 730, Third port; 740, Fourth port; 750, Fifth port; 760, Sixth port;
[0044] 800 stainless steel connecting pipe. Detailed Implementation
[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.
[0046] Please see Figure 1 and Figure 2 The present invention provides a dual-column backflushing system, comprising: a pneumatic eight-way valve 100, a first pneumatic six-way valve 300, a second pneumatic six-way valve 700, a first capillary column 400, a second capillary column 500, a flow-limiting quartz capillary 200, a stainless steel connecting pipe 800, and a pneumatic control module.
[0047] Specifically, the pneumatic eight-way valve 100 is installed in the GasBench multifunctional gas preparation and introduction system, and has a first port 110 to an eighth port 180: the first port 110 is connected to a helium source, the second port 120 is the second exhaust port (vent 2), the third port 130 is connected to one end of the metering loop (not shown) provided with the GasBench, the fourth port 140 is connected to the first pneumatic six-way valve 300 through a flow-limiting quartz capillary tube 200, the fifth port 150 is connected to a helium source, the sixth port 160 is connected to the other end of the metering loop (not shown), the seventh port 170 is connected to the sample introduced into the GasBench multifunctional gas preparation and introduction system, and the eighth port 180 is the first exhaust port (vent 1). The pneumatic eight-way valve 100 is controlled and automatically pneumatically switched by the software program provided with the GasBench.
[0048] The first pneumatic six-way valve 300 has a first port 310 to a sixth port 360: the first port 310 is connected to the fourth port 140 of the pneumatic eight-way valve 100 via a flow-limiting quartz capillary tube 200; the second port 320 is the fourth exhaust port vent 4; the third port 330 is unused; the fourth port 340 is the fifth exhaust port vent 5; the fifth port 350 is connected to the sixth port 760 of the second pneumatic six-way valve 700 via a stainless steel connecting tube 800; and the sixth port 360 is connected to the inlet of the second capillary chromatographic column 500. The first pneumatic six-way valve 300 is controlled by software and automatically switches between pneumatic modes.
[0049] The second pneumatic six-way valve 700 has a first port 710 to a sixth port 760: the first port 710 is connected to one end of the first capillary column 400 via a quartz capillary tube; the second port 720 is connected to a helium source; the third port 730 is the third exhaust port (vent 3); the fourth port 740 is connected to the other end of the first capillary column 400 via a quartz capillary tube; the fifth port 750 is connected to the sample gas collected by the Precon pre-concentration device; and the sixth port 760 is connected to the fifth port 350 of the first pneumatic six-way valve 300 via a stainless steel connecting pipe 800. The second pneumatic six-way valve 700 is controlled by software and automatically switches pneumatically. It should be noted that the specific programming implementation of the software program in this invention adopts conventional methods in the art, and this invention does not limit it in this regard.
[0050] The first capillary column 400 is an Rt-Q-BOND fused silica PLOT column, 15m long and 0.32mm in inner diameter. Both ends are connected to the first port 710 and the fourth port 740 of the second pneumatic six-way valve 700 through quartz capillaries. It is placed in a column oven and can be aged and purified by heating in the column oven.
[0051] The second capillary column 500 is an Rt-Q-BOND fused silica PLOT column, 15m long and 0.32mm inner diameter. One end is connected to the sixth port 360 of the first pneumatic six-way valve 300 via a quartz capillary, and the other end is connected to the Nafion dehydration tube 600 of GasBench via a quartz capillary. It is placed in a column oven and can be aged and purified by heating in the column oven.
[0052] The flow-limiting quartz capillary 200 has an outer diameter of 220μm, an inner diameter of 150μm, and a length of 1m. It is connected between the fourth port 140 of the pneumatic eight-way valve 100 and the first port 310 of the first pneumatic six-way valve 300.
[0053] The stainless steel connecting pipe 800 is a 1 / 16-inch stainless steel pipe, which connects between the sixth port 760 of the second pneumatic six-way valve 700 and the fifth port 350 of the first pneumatic six-way valve 300.
[0054] The pneumatic control module (not shown) uses the pneumatic valve control interface reserved in the multi-purpose online gas preparation and introduction system to connect with the first pneumatic six-way valve 300 and the second pneumatic six-way valve 700, and automatically controls the switching of the two pneumatic six-way valves through software program.
[0055] Specifically, the pneumatic control module is connected to the first pneumatic six-way valve 300 and the second pneumatic six-way valve 700. The control interfaces of the pneumatic control modules of the first pneumatic six-way valve 300 and the second pneumatic six-way valve 700 use GasBench trap 1 (Trap 1) and trap 2 (Trap 2) interfaces to achieve automatic control. The Trap 1 up state corresponds to the sample injection state of the first pneumatic six-way valve 300, and the Trap 1 down state corresponds to the backflushing state of the first pneumatic six-way valve 300; the Trap 2 up state corresponds to the sample injection state of the second pneumatic six-way valve 700, and the Trap 2 down state corresponds to the backflushing state of the second pneumatic six-way valve 700.
[0056] Please see Figure 1 , Figure 2 and Figure 3 Based on the above system, the present invention provides a dual-column backflushing method, comprising the following steps:
[0057] S1. In the injection state, switch the second pneumatic six-way valve 700 and the first pneumatic six-way valve 300 to the injection position, so that the first capillary column 400 and the second capillary column 500 are connected in series. The carrier gas high-purity helium (He) carries the sample gas through the first capillary column 400 and the second capillary column 500 in sequence for component separation.
[0058] S2. In the backflush state, switch the first pneumatic six-way valve 300 and the second pneumatic six-way valve 700 to the backflush position to reverse the gas flow in the first capillary chromatographic column 400 and discharge the volatile organic impurities retained in the first capillary chromatographic column 400 in the reverse direction.
[0059] It should be noted that the pneumatic control module automatically controls the switching between the first pneumatic six-way valve 300 and the second pneumatic six-way valve 700 between the sample injection position and the backflush position.
[0060] In some embodiments, connecting the first capillary column 400 and the second capillary column 500 in series in S1 includes: switching the second pneumatic six-way valve 700 and the first pneumatic six-way valve 300 to the injection position, with the carrier gas carrying the sample gas entering through the fifth port 750 of the second pneumatic six-way valve 700, sequentially passing through the fourth port 740, the first capillary column 400, the first port 710, the sixth port 760, and the stainless steel connecting tube 800 into the fifth port 350 of the first pneumatic six-way valve 300, and then entering the second capillary column 500 through the sixth port 360 of the first pneumatic six-way valve 300.
[0061] Specifically, please see Figure 1 The sample introduction gas path shown uses high-purity helium (He) as the carrier gas to carry the sample gas. It first enters the fifth port 750 of the second pneumatic six-way valve 700, and then enters the first capillary column 400 after passing through the fourth port 740. Due to the different retention times of different components in the sample gas in the column, the target compound gas N2O and impurity gases such as CO2 and VOCs are gradually separated. The impurity gas CO2 and the target compound gas N2O first flow out of the first capillary column 400, and then enter the first pneumatic six-way valve 300 through the first port 710 and the sixth port 760 of the second pneumatic six-way valve 700 and the stainless steel connecting pipe 800. They then enter the second capillary column 500 through the fifth port 350 and the sixth port 360 in sequence. In the second capillary column 500, the target compound gas N2O and the impurity gas CO2 continue to be separated. After separation, the target gas is dehydrated by the Nafion dehydration pipe 600 and then enters the stable isotope ratio mass spectrometer for analysis.
[0062] In some embodiments, reversing the gas flow direction in the first capillary column 400 in S2 includes: simultaneously switching the first pneumatic six-way valve 300 and the second pneumatic six-way valve 700 to the backflush position; high-purity helium gas from the fifth port 150 of the pneumatic eight-way valve 100 sequentially enters the second capillary column 500 through the fourth port 140 of the pneumatic eight-way valve 100, the flow-limiting quartz capillary 200, the first port 310 and the sixth port 360 of the first pneumatic six-way valve 300, continuing the separation of the target compound gas and the impurity gas; simultaneously, high-purity helium gas from the second port 720 of the second pneumatic six-way valve 700 enters the first capillary column 400 and flows out from the third port 730 of the second pneumatic six-way valve 700, backflushing out the volatile organic impurities retained in the first capillary column 400.
[0063] Specifically, high-purity helium gas from the fifth port 150 of the pneumatic eight-way valve 100 sequentially passes through the fifth port 150 and the fourth port 140 of the pneumatic eight-way valve 100, the flow-limiting quartz capillary 200, and the first port 310 and the sixth port 360 of the first pneumatic six-way valve 300 into the second capillary column 500 to continue the separation of the target compound gas N2O and the impurity gas CO2. After the second pneumatic six-way valve 700 is switched, the gas flow direction in the first capillary column 400 is reversed, and a stream of high-purity helium gas enters the first capillary column 400 from the second port 720 of the second pneumatic six-way valve 700 and flows out from the third port 730, thereby discharging VOCs and other impurity gases from the first capillary column 400, thus reducing the contamination of the column and ion source by impurities, improving detection stability, and extending the service life of the column.
[0064] This invention modifies the existing Thermo Scientific GasBench multifunctional gas preparation and introduction system by adding two pneumatic six-way valves connected to the original gasbench eight-way valve. While retaining the instrument's original functions, it enables first-stage column backflushing, effectively removing VOCs and other impurities from samples and reducing instrument background. Through column backflushing, nitrates, nitrites, ammonia nitrogen, and N2O gas converted from dissolved organic nitrogen are further purified. This purification process is highly efficient and automated, reducing instrument background and improving sample testing stability.
[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A dual-column backflush system, characterized in that, include: A pneumatic eight-way valve (100) has one port connected to a first pneumatic six-way valve (300) via a flow-limiting quartz capillary tube (200) and another port connected to a helium source; The first pneumatic six-way valve (300) has one port connected to the second pneumatic six-way valve (700) via a stainless steel connecting pipe (800), and the other port connected to the inlet of the second capillary chromatographic column (500). The second pneumatic six-way valve (700) has two ports connected to the two ends of the first capillary chromatographic column (400) respectively, and one port is connected to the carrier gas to carry the sample gas. By switching the first pneumatic six-way valve (300) and the second pneumatic six-way valve (700), the carrier gas carries the sample gas through the first capillary column (400) and the second capillary column (500) for component separation, and the gas flow direction in the first capillary column (400) is reversed to remove impurities.
2. The system according to claim 1, characterized in that, The pneumatic eight-way valve (100) has a first port (110) to an eighth port (180); the first port (110) is connected to a helium source, the second port (120) is a second exhaust port, the third port (130) is connected to one end of a metering ring, the fourth port (140) is connected to the first pneumatic six-way valve (300) through the flow-limiting quartz capillary tube (200), the fifth port (150) is connected to a helium source, the sixth port (160) is connected to the other end of the metering ring, and the eighth port (180) is a first exhaust port.
3. The system according to claim 2, characterized in that, The first pneumatic six-way valve (300) has a first port (310) to a sixth port (360); the first port (310) is connected to the fourth interface (140) through the flow-limiting quartz capillary (200), the second port (320) is the fourth exhaust port, the third port (330) is unused, the fourth port (340) is the fifth exhaust port, the fifth port (350) is connected to the second pneumatic six-way valve (700) through the stainless steel connecting pipe (800), and the sixth port (360) is connected to the inlet of the second capillary chromatographic column (500).
4. The system according to claim 3, characterized in that, The second pneumatic six-way valve (700) has a first port (710) to a sixth port (760); the first port (710) is connected to one end of the first capillary column (400), the second port (720) is connected to a helium source, the third port (730) is a third exhaust port, the fourth port (740) is connected to the other end of the first capillary column (400), the fifth port (750) is connected to a carrier gas to carry the sample gas, and the sixth port (760) is connected to the fifth port (350) through the stainless steel connecting pipe (800).
5. The system according to claim 1, characterized in that, Both the first capillary column (400) and the second capillary column (500) are placed in a column oven; both the first capillary column (400) and the second capillary column (500) are Rt-Q-BOND fused silica PLOT columns, with a length of 15m and an inner diameter of 0.32mm; the flow-limiting quartz capillary (200) has an outer diameter of 220μm, an inner diameter of 150μm, and a length of 1m; the stainless steel connecting tube (800) is a 1 / 16-inch stainless steel tube.
6. A dual-column backflushing method using the system according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. In the injection state, switch the second pneumatic six-way valve (700) and the first pneumatic six-way valve (300) to the injection position, so that the first capillary column (400) and the second capillary column (500) are connected in series, and the carrier gas carries the sample gas through the first capillary column (400) and the second capillary column (500) in sequence for component separation; S2. In the backflush state, switch the first pneumatic six-way valve (300) and the second pneumatic six-way valve (700) to the backflush position, so that the gas flow in the first capillary column (400) is reversed, and the volatile organic impurities retained in the first capillary column (400) are discharged in the reverse direction.
7. The method according to claim 6, characterized in that, In the injection state, the second pneumatic six-way valve (700) and the first pneumatic six-way valve (300) are switched to the injection position, so that the first capillary column (400) and the second capillary column (500) are connected in series. The carrier gas carries the sample gas through the first capillary column (400) and the second capillary column (500) in sequence for component separation, including: Switch the second pneumatic six-way valve (700) and the first pneumatic six-way valve (300) to the injection position. The carrier gas carrying the sample gas enters through the fifth port (750), and sequentially enters the first capillary chromatographic column (400) through the fourth port (740) to separate the target compound gas and impurity gas. Then, it enters the fifth port (350) through the first port (710), the sixth port (760), and the stainless steel connecting tube (800), and then enters the second capillary chromatographic column (500) through the sixth port (360) for further separation of the target compound gas and impurity gas.
8. The method according to claim 6, characterized in that, In the backflush state, the first pneumatic six-way valve (300) and the second pneumatic six-way valve (700) are switched to the backflush position, causing the gas flow in the first capillary column (400) to reverse, and the volatile organic impurities retained in the first capillary column (400) to be discharged in the reverse direction, including: When the first pneumatic six-way valve (300) and the second pneumatic six-way valve (700) are simultaneously switched to the backflush position, the high-purity helium gas from the fifth port (150) enters the second capillary column (500) sequentially through the fourth port (140), the flow-limiting quartz capillary (200), the first port (310), and the sixth port (360) to continue the separation of the target compound gas and the impurity gas; at the same time, the high-purity helium gas from the second port (720) enters the first capillary column (400) and flows out from the third port (730) to backflush out the volatile organic impurities retained in the first capillary column (400).
9. The method according to claim 6, characterized in that, Also includes: The first capillary column (400) and the second capillary column (500) are placed in a column oven, and the first capillary column (400) and the second capillary column (500) are aged and purified by heating in the column oven.