Automatic sample injection and impurity analysis system for octafluoropropane crude product and use method of automatic sample injection and impurity analysis system

Abstract

The invention discloses an octafluoropropane crude product automatic sample injection and impurity analysis system and a use method thereof. The system comprises a color detector, two ten-way valves, two six-way switching valves and a thermal conductivity detector, a silica gel drying column is connected to a branch between a first pneumatic valve and a second pneumatic valve, and the other end of the silica gel drying column is connected with a sample inlet pipe; the detection range of the color detector covers the whole silica gel drying column, and the color detector is linked with the pneumatic valve; the first ten-way valve is respectively connected with a second twenty-way valve and a first six-way switching valve; the first six-way switching valve is further connected with a second twenty-way valve and a second six-way switching valve. And the second six-way switching valve is connected with the thermal conductivity detector. According to the invention, HF and F2 are prevented from corroding the chromatography, automatic continuous analysis of the octafluoropropane crude product is realized, detection equipment is effectively protected, and the service life of the equipment is prolonged; the impurities in the octafluoropropane are detected in groups, so that the analysis efficiency of an analysis sample is effectively improved, the analysis time is shortened to 30 minutes, and the ppm-level content impurity detection requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of industrial gas analysis and detection technology, specifically relating to an automatic sampling system and impurity analysis method in the production process of crude octafluoropropane (C3F8), which is particularly suitable for online quality monitoring of fluorocarbon compounds containing corrosive impurities. Background Technology

[0002] Octafluoropropane is a high-density (approximately 1.66 g / cm³) and low-boiling-point (-36.7℃) inert fluorocarbon compound. Due to its excellent chemical stability and low toxicity, it is widely used in microelectronics industries for plasma etching, semiconductor device cleaning, and special gas insulation. Currently, octafluoropropane is mainly synthesized industrially through the catalytic addition process of hexafluoropropylene and fluorine (F₂). However, the crude product obtained during this process contains trace amounts of hydrogen fluoride (HF) and unreacted free fluorine (F₂). These corrosive gases can directly corrode analytical equipment in subsequent analytical processes, leading to distorted analytical data and significantly shortening equipment lifespan. Therefore, effectively preventing corrosive gases from entering analytical equipment and achieving rapid and efficient analysis has become a critical need that urgently requires a solution.

[0003] Currently, mature analytical methods mainly employ PQ packed columns in gas chromatography, combined with helium ionization detectors, for the quantitative analysis of non-corrosive impurities in electronic-grade octafluoropropane. However, this approach has the following limitations: 1. It cannot avoid the corrosive effects of HF and F2 on the chromatogram, causing baseline drift, reduced detector sensitivity, and even permanent damage; 2. PQ packed columns have long detection times; 3. Helium ionization detectors cannot detect high levels of impurities, limiting their analytical capabilities; 4. Octafluoropropane molecules have strong polarity, and traditional detection techniques result in single-analysis cycles exceeding 90 minutes, failing to meet the real-time quality monitoring requirements of continuous production lines. Summary of the Invention

[0004] To fill the gap in existing technologies for the detection of crude octafluoropropane, the first technical problem this invention aims to solve is to provide an automated sample introduction and impurity analysis system for crude octafluoropropane, enabling quantitative and qualitative analysis of impurities in the crude product, solving the corrosion problem of fluorine and hydrogen fluoride in the crude product on the analytical equipment, and effectively improving the sample analysis rate.

[0005] The second technical problem to be solved by the present invention is to provide a method for using the analysis system.

[0006] To solve the first technical problem mentioned above, the present invention adopts the following technical solution: an automated sample injection and impurity analysis system for crude octafluoropropane, comprising a color detector, two 10-way valves, two 6-way switching valves, and a thermal conductivity detector; a silica gel drying column 2 is connected to a branch between the first pneumatic valve 31 and the second pneumatic valve 32, and the other end of the silica gel drying column 2 is connected to a sample inlet tube; the color detector 1 has a detection range covering the entire silica gel drying column, and the color detector is linked with the pneumatic valves; the first port ① of the first 10-way valve 71 is connected to the second pneumatic valve 32-first pneumatic valve 31-vent tube, the second port ② is connected to the first port ① of the second 10-way valve 72, the third port ③ is connected to the ⑩ port through the first quantitative loop 41, the ④ port is connected to a carrier gas tube, the ⑤ port is connected to the ⑥ port of the first 6-way switching valve 91 through the first separation chromatographic column 81, and the ⑥ port is connected to the first pre-separation chromatographic column. 61 connects to port 9, port 7 connects to the vent tube, and port 8 connects to the carrier gas tube; port 2 of the 20-way valve 72 connects to pressure sensor 5, port 3 connects to port 10 via the second metering ring 42, port 4 connects to external carrier gas, port 5 connects to port 9 via the second pre-separation column 62, port 6 connects to port 2 of the first six-way switching valve 91 via the second separation column 82, port 7 connects to external carrier gas tube, and port 8 connects to the vent tube; port 1 of the first six-way switching valve 91 connects to port 6 of the second six-way switching valve 92, port 3 connects to the vent port, port 4 connects to external carrier gas tube, and port 5 connects to the vent tube; port 1 of the second six-way switching valve 92 connects to the vent tube, port 2 connects to port 4, and port 5 connects to thermal conductivity detector 10.

[0007] Furthermore, commercially available high-precision color detectors are preferred.

[0008] Furthermore, the first pre-separation chromatographic column is preferably a 0.6 m × 1 / 8" CAST column.

[0009] Furthermore, the second pre-separation column is preferably a 2 m × 1 / 8" Q column.

[0010] Furthermore, the first separation chromatographic column is preferably a 2 m × 1 / 8" 5A column.

[0011] Furthermore, the second separation column is preferably a 30 m × 0.32 mm Agilent GasPro column.

[0012] Furthermore, corrosion-resistant tubing is used in the sample gas path.

[0013] Furthermore, the second separation chromatographic column is configured with a temperature ramp-up setting.

[0014] In the analysis system, the first and second 10-way switching valves are used to switch between sample and carrier gas; the first 6-way switching valve is used for venting the main component; and the second 6-way switching valve is used to select the detector.

[0015] Appendix Figure 1 All switching valves are in the "open" position, attached Figure 2 All switching valves are in the "closed" state. Each switching valve is initially in the "closed" state, switches to "open" after one switch, and switches back to "closed" after another switch.

[0016] To solve the second technical problem mentioned above, the present invention provides a method for using an automated sample introduction and impurity analysis system for crude octafluoropropane, comprising the following steps: (1) Automatic sample injection: After the crude octafluoropropane is passed into the silica gel drying column, it enters the analysis system. The crude product contains fluorine gas or hydrogen fluoride. The silica gel changes from blue to black. The optical detector detects the color change of the silica gel, closes the second pneumatic valve 32, opens the first pneumatic valve 31, and the sample stops entering the analysis system. The sample gas remaining in the pipeline is vented. (2) Close the first ten-way switching valve 71, and the first quantitative loop 41 starts collecting samples; close the second ten-way switching valve 72, and the second quantitative loop 42 starts collecting samples; (3) Open the first ten-way switching valve 71 to analyze the sample collected by the first quantitative loop 41; open the second ten-way switching valve 72 to analyze the sample collected by the second quantitative loop 42; (4) Analysis of oxygen, nitrogen, methane, and carbon monoxide: Open the first 10-port switching valve 71 and keep the 20-port switching valve 72 closed. The carrier gas carries the sample in the first quantitative loop 41 into the first pre-separation chromatographic column 61, where the components in the sample are pre-separated. Then, the pre-separated sample enters the first separation chromatographic column 81, where the components are separated into oxygen, nitrogen, methane, carbon monoxide, and other components. Open the first 6-port switching valve 91, and the oxygen, nitrogen, methane, and carbon monoxide components enter the second 6-port switching valve 92, while the other components are vented. Open the second 6-port switching valve 92, and the analyte enters the thermal conductivity detector 10 for analysis. (5) Analysis of CF4, NF3, C2F6, C3F8, C3F6, and C3HF7: Keep the first ten-way switching valve 71 open, open the second ten-way switching valve 72, open the first six-way switching valve 91, and the carrier gas carries the sample in the second quantitative ring 42 into the second pre-separation chromatographic column 62. The components in the sample are pre-separated and then enter the second chromatographic separation column 82 to separate the components CF4, NF3, C2F6, C3F8, C3F6, and C3HF7. The components enter the second six-way switching valve 92 and wait to enter the detector for analysis. Open the second six-way switching valve 92 and the components to be measured enter the thermal conductivity detector 10 for analysis. (6) Temperature program for the second separation column: The initial temperature of the second separation column is 70℃, held for 5 min, then increased to 160℃ at 15℃ / min, and held at 160℃ for 19 min. The total analysis time is 30 min.

[0017] The preferred carrier gas in the analysis system is helium with a purity of 99.9999%.

[0018] The advantages of this invention are: 1. Set up a program that links the color detector and the pneumatic valve. By detecting the color of the silica gel column, set up an automatic sample injection program to avoid corrosion of the chromatograph by HF and F2, realize automatic and continuous analysis of crude octafluoropropane, and effectively protect the detection equipment and extend its service life.

[0019] 2. This method separates impurities in octafluoropropane into oxygen, nitrogen, methane, carbon monoxide, and CF4, NF3, C2F6, C3F8, C3F6, and C3HF7 for group detection, which effectively improves the efficiency of sample analysis.

[0020] 3. The second separation column in this protocol is equipped with programmed temperature rise, which reduces the analysis time of fluorocarbons to 30 minutes.

[0021] 4. This solution is equipped with a thermal conductivity detector, which can meet the detection requirements of impurities at the ppm level. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the "open" state of the switching valve in the automatic sampling and impurity analysis system for crude octafluoropropane of the present invention.

[0024] Figure 2 This is a schematic diagram of the "off" state of the switching valve in the automatic sampling and impurity analysis system for crude octafluoropropane of the present invention.

[0025] Figure 3 Example 3: Detection graphs of oxygen, nitrogen, methane, and carbon monoxide.

[0026] Figure 4 The detection images are for CF4, NF3, C2F6, C3F8, C3F6, and C3HF7 in Example 3.

[0027] The components include: 1. Color detector, 2. Silica gel drying column, 31. First pneumatic valve, 32. Second pneumatic valve, 41. First quantitative loop, 42. Second quantitative loop, 5. Pressure sensor, 61. First pre-separation column, 62. Second pre-separation column, 71. First ten-way switching valve, 72. Second ten-way switching valve, 81. First separation column, 82. Second separation column, 91. First six-way switching valve, 92. Second six-way switching valve, and 10. Thermal conductivity detector. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 , Figure 2 As shown, an automated sample injection and impurity analysis system for crude octafluoropropane includes a color detector, two 10-way valves, two 6-way switching valves, and a thermal conductivity detector. A silica gel drying column 2 is connected to a branch between the first pneumatic valve 31 and the second pneumatic valve 32, with the other end of the silica gel drying column 2 connected to a sample inlet tube. The color detector 1 has a detection range covering the entire silica gel drying column and is linked with the pneumatic valves. The first port ① of the first 10-way valve 71 is connected to the second pneumatic valve 32-first pneumatic valve 31-vent tube; the second port ② is connected to the first port ① of the second 10-way valve 72; the third port ③ is connected to the ⑩ port through the first quantitative loop 41; the fourth port ④ is connected to a carrier gas tube; the fifth port ⑤ is connected to the ⑥ port of the first 6-way switching valve 91 through the first separation chromatographic column 81; and the sixth port ⑥ is connected to the first pre-separation chromatographic column. Column 61 is connected to port 9, port 7 is connected to the vent tube, and port 8 is connected to the carrier gas tube; port 2 of the 20-way valve 72 is connected to pressure sensor 5, port 3 is connected to port 10 via the second quantitative loop 42, port 4 is connected to external carrier gas, port 5 is connected to port 9 via the second pre-separation column 62, port 6 is connected to port 2 of the first six-way switching valve 91 via the second separation column 82, port 7 is connected to external carrier gas tube, and port 8 is connected to the vent tube; port 1 of the first six-way switching valve 91 is connected to port 6 of the second six-way switching valve 92, port 3 is connected to the vent port, port 4 is connected to external carrier gas tube, and port 5 is connected to the vent tube; port 1 of the second six-way switching valve 92 is connected to the vent tube, port 2 is connected to port 4, and port 5 is connected to the thermal conductivity detector 10.

[0031] Furthermore, commercially available high-precision color detectors are preferred.

[0032] Furthermore, the first pre-separation chromatographic column is preferably a 0.6 m × 1 / 8" CAST column.

[0033] Furthermore, the second pre-separation column is preferably a 2 m × 1 / 8" Q column.

[0034] Furthermore, the first separation chromatographic column is preferably a 2 m × 1 / 8" 5A column.

[0035] Furthermore, the second separation column is preferably a 30 m × 0.32 mm Agilent GasPro column.

[0036] Furthermore, corrosion-resistant tubing is used in the sample gas path.

[0037] Furthermore, the second separation chromatographic column is configured with a temperature ramp-up setting.

[0038] Appendix Figure 1 All switching valves are in the "open" position, attached Figure 2 All switching valves are in the "closed" state. Each switching valve is initially in the "closed" state, switches to "open" after one switch, and switches back to "closed" after another switch.

[0039] Example 1 As attached Figure 1 and attached Figure 2 The analytical system shown is used for the analysis and detection of ppm-level impurities in crude octafluoropropane. The analysis of oxygen, nitrogen, methane, and carbon monoxide in crude octafluoropropane includes the following steps: 1. Automatic sample introduction: After crude octafluoropropane is introduced into the silica gel drying column, it enters the analysis system. The crude product contains fluorine gas or hydrogen fluoride. The silica gel changes from blue to black. When the optical detector detects the color change of the silica gel, the second pneumatic valve 32 is closed and the first pneumatic valve 31 is opened. The sample stops entering the analysis system and the residual sample gas in the pipeline is vented.

[0040] 2. Appendix Figure 1 All switching valves are in the "open" position, attached Figure 2 All switching valves are in the "closed" state. Each switching valve is initially in the "closed" state, switches to "open" after one switch, and switches back to "closed" after another switch.

[0041] 3. Close the first ten-way switching valve 71, and the first quantitative loop 41 will start collecting samples; close the second ten-way switching valve 72, and the second quantitative loop 42 will start collecting samples.

[0042] 4. Open the first 10-port switching valve 71 and keep the second 10-port switching valve 72 closed. The carrier gas passes through port 4 of the first 10-port switching valve 71 → port 3 → first quantitative loop 41 → port 10 → port 9 → first pre-separation chromatographic column 61 to achieve pre-separation of the components in the sample.

[0043] 5. After pre-separation by the first pre-separation column 61, each component is separated into oxygen, nitrogen, methane, carbon monoxide and other components by the first ten-way switching valve 71, which passes through port 6 → port 5.

[0044] 6. Oxygen, nitrogen, methane, carbon monoxide and other components enter port 6 of the first six-way switching valve 91. After opening the first six-way switching valve 91, oxygen, nitrogen, methane and carbon monoxide flow out from port 1 of the first six-way switching valve 91. Then close the first six-way switching valve 91, and other components are vented from port 5 of the first six-way switching valve 91.

[0045] 7. Open the second six-way switching valve 92. Oxygen, nitrogen, methane, and carbon monoxide enter the second six-way switching valve 92 through port 6 → port 5 → thermal conductivity detector 10 for analysis.

[0046] 8. After injection, the final elution order of impurities in the crude octafluoropropane was: oxygen, nitrogen, methane, and carbon monoxide. The elution times were 1.098 min, 1.723 min, 3.123 min, and 4.905 min, respectively.

[0047] Example 2 As attached Figure 1 and attached Figure 2 The analytical system shown is used for the analysis and detection of ppm-level impurities in crude octafluoropropane. The analysis of CF4, NF3, C2F6, C3F8, C3F6, and C3HF7 in crude octafluoropropane includes the following steps: 1. Automatic sample introduction: After crude octafluoropropane is introduced into the silica gel drying column, it enters the analysis system. The crude product contains fluorine gas or hydrogen fluoride. The silica gel changes from blue to black. When the optical detector detects the color change of the silica gel, the second pneumatic valve 32 is closed and the first pneumatic valve 31 is opened. The sample stops entering the analysis system and the residual sample gas in the pipeline is vented.

[0048] 2. Appendix Figure 1 All switching valves are in the "open" position, attached Figure 2 All switching valves are in the "closed" state. Each switching valve is initially in the "closed" state, switches to "open" after one switch, and switches back to "closed" after another switch.

[0049] 3. Close the first ten-way switching valve 71, and the first quantitative loop 41 will start collecting samples; close the second ten-way switching valve 72, and the second quantitative loop 42 will start collecting samples.

[0050] 4. Keep the first 10-port switching valve 71 closed, open the 20-port switching valve 72, and the carrier gas passes through port 4 → port 3 → second quantitative loop 42 → port 10 → port 9 of the 20-port switching valve 72 to the second pre-separation chromatographic column 62 to achieve pre-separation of the components in the sample.

[0051] 5. After pre-separation by the second pre-separation column 62, each component is separated into CF4, NF3, C2F6, C3F8, C3F6, and C3HF7 by the second separation column 82 through port 5 → port 6 of the 20th-port switching valve 72.

[0052] 6. Keep the first six-way switching valve 91 closed. CF4, NF3, C2F6, C3F8, C3F6, and C3HF7 enter port 2 of the first six-way switching valve 91 and flow out through port 1.

[0053] 7. Open the second six-way switching valve 92. CF4, NF3, C2F6, C3F8, C3F6, and C3HF7 enter the second six-way switching valve 92 through port 6 → port 5 → thermal conductivity detector 10 for analysis.

[0054] 8. After injection, the final elution order of impurities in the crude octafluoropropane was: CF4, NF3, C2F6, C3F8, C3F6, C3HF7. The elution times were 6.750 min, 7.388 min, 12.473 min, 18.085 min, 19.737 min, and 26.222 min, respectively.

[0055] 9. During the analysis, the second separation column was programmed to increase the temperature. Initially, the column oven was kept at 70°C for 5 minutes. After 5 minutes, the temperature was increased to 160°C at a rate of 15°C / min and held for 16 minutes. The total analysis time was 30 minutes.

[0056] Example 3

[0057] An automated sampling and impurity analysis system for crude octafluoropropane and its usage method are the same as in Examples 1 and 2.

[0058] Based on the automated sample introduction and impurity analysis system for crude octafluoropropane and its usage method, a bottle of standard gases with helium as the balance gas was analyzed, and the contents of each group were divided into oxygen (1007.7 ppm), nitrogen (481.1 ppm), methane (50.7 ppm), carbon monoxide (50.7 ppm), CF (449.85 ppm), NF (3499.47 ppm), C2F (699.6 ppm), C3F (8499.47 ppm), C3F (699.6 ppm), and C3HF (7499.47 ppm). The results are as follows: Figure 3 and Figure 4As shown, an automated sampling and impurity analysis system for crude octafluoropropane and its usage method enable ppm-level impurity detection.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. An automated sampling and impurity analysis system for crude octafluoropropane, characterized in that, It includes a color detector, two 10-way valves, two 6-way switching valves, and a thermal conductivity detector. A silica gel drying column (2) is connected to the branch between the first pneumatic valve (31) and the second pneumatic valve (32), and the other end of the silica gel drying column (2) is connected to the sample inlet tube. The detection range of the color detector (1) covers the entire silica gel drying column, and the color detector is linked with the pneumatic valves. The first port ① of the first 10-way valve (71) is connected to the second pneumatic valve (32) - the first pneumatic valve (31) - the vent tube, the second port ② is connected to the first port ① of the second 10-way valve (72), the third port ③ is connected to the ⑩ port through the first quantitative loop (41), the fourth port ④ is connected to the carrier gas tube, the fifth port ⑤ is connected to the ⑥ port of the first 6-way switching valve (91) through the first separation chromatographic column (81), and the sixth port ⑥ is connected to the ⑨ port through the first pre-separation chromatographic column (61). The 7th port is connected to the vent pipe, and the 8th port is connected to the carrier gas pipe; the 2nd port of the 20th valve (72) is connected to the pressure sensor (5), the 3rd port is connected to the 10th port through the second quantitative ring (42), the 4th port is connected to the carrier gas, the 5th port is connected to the 9th port through the second pre-separation chromatographic column (62), the 6th port is connected to the 2nd port of the first six-way switching valve (91) through the second separation chromatographic column (82), the 7th port is connected to the carrier gas pipe, and the 8th port is connected to the vent pipe; the 1st port of the first six-way switching valve (91) is connected to the 6th port of the second six-way switching valve (92), the 3rd port is connected to the vent port, the 4th port is connected to the carrier gas pipe, and the 5th port is connected to the vent pipe; the 1st port of the second six-way switching valve (92) is connected to the vent pipe, the 2nd port is connected to the 4th port, and the 5th port is connected to the thermal conductivity detector (10).

2. The automated sampling and impurity analysis system for crude octafluoropropane according to claim 1, characterized in that, The first pre-separation column was a 0.6 m × 1 / 8" CAST column; the second pre-separation column was a 2 m × 1 / 8" Q column; the first separation column was a 2 m × 1 / 8" 5A column; and the second separation column was a 30 m × 0.32 mm Agilent GasPro column.

3. The automated sample introduction and impurity analysis system for crude octafluoropropane according to claim 1, characterized in that, The sample gas path uses corrosion-resistant tubing.

4. The automated sample introduction and impurity analysis system for crude octafluoropropane according to claim 1, characterized in that, The second separation column is configured with a temperature ramp-up program.

5. A method of using the automated sample introduction and impurity analysis system for crude octafluoropropane as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Automatic sample injection: After the crude octafluoropropane is passed into the silica gel drying column, it enters the analysis system. The crude product contains fluorine gas or hydrogen fluoride. The silica gel changes from blue to black. The optical detector detects the color change of the silica gel, closes the second pneumatic valve (32), opens the first pneumatic valve (31), and the sample stops entering the analysis system. The sample gas remaining in the pipeline is vented. (2) Close the first ten-way switching valve (71), and the first quantitative loop (41) begins to collect samples; close the second ten-way switching valve (72), and the second quantitative loop (42) begins to collect samples; (3) Open the first ten-way switching valve (71) to analyze the sample collected by the first quantitative loop (41); open the second ten-way switching valve (72) to analyze the sample collected by the second quantitative loop (42); (4) Analysis of oxygen, nitrogen, methane and carbon monoxide: Open the first ten-port switching valve (71) and keep the second ten-port switching valve (72) closed. The carrier gas carries the sample in the first quantitative loop (41) into the first pre-separation chromatographic column (61) to pre-separate the components in the sample. Then the pre-separated sample enters the first separation chromatographic column (81) to separate the components into oxygen, nitrogen, methane, carbon monoxide and other components. Open the first six-port switching valve (91) and the oxygen, nitrogen, methane and carbon monoxide components enter the second six-port switching valve (92) while the other components are vented. Open the second six-way switching valve (92) and the component to be measured enters the thermal conductivity detector (10) for analysis; (5) Analysis of CF4, NF3, C2F6, C3F8, C3F6, and C3HF7: Keep the first ten-way switching valve (71), open the second ten-way switching valve (72), open the first six-way switching valve (91), and the carrier gas carries the sample in the second quantitative ring (42) into the second pre-separation chromatographic column (62). The components in the sample are pre-separated and then enter the second chromatographic separation column (82) to separate the components CF4, NF3, C2F6, C3F8, C3F6, and C3HF7. The components enter the second six-way switching valve (92) and wait to enter the detector for analysis. Open the second six-way switching valve 92 and the measured components enter the thermal conductivity detector (10) for analysis. (6) Temperature program for the second separation column: The initial temperature of the second separation column is 70℃, held for 5 min, then increased to 160℃ at 15℃ / min, and held at 160℃ for 19 min. The total analysis time is 30 min.

6. The method of use according to claim 5, characterized in that, The carrier gas in the analysis system is helium with a purity of 99.9999%.

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