CN104458970B - A kind of thermal desorption device - Google Patents

Abstract

The present invention relates to sample detection technical field, it is thermal desorption device that is a kind of and gas chromatograph coupling, be mainly used in solid-phase microextraction rod, stir bar sorptive extraction, bundling capillary pipe solid phase micro-extraction pipe and fill the thermal desorption of adsorption column, by the trace components fast desorption of institute's adsorption and enrichment out.This device is by heating tube, and internal lining pipe, O-ring seal, internal lining pipe pressure cap, internal lining pipe base, the adiabatic ring of internal lining pipe base, desorption device base, sample conveying tube, desorb purges gas circuit, desorption distributary gas circuit, and heater strip and temperature control element composition.Sample component completes thermal desorption in internal lining pipe, and the heating of sample conveying tube is completed jointly by the heat transfer of cap on heating tube and gas phase chromatic spectrum sample feeder, and by the adiabatic environmental protection temperature of internal lining pipe base.When desorption temperature 300 DEG C, this thermal desorption device is residual lower than 0.1% to the component desorb of boiling point less than 430 DEG C, the advantage such as have desorb sample channel cold area free, firing rate is fast, power consumption is low.

Description

A thermal desorption device

technical field

The invention relates to the technical field of sample detection, belongs to analytical chemical sample pretreatment devices, is a thermal desorption device used in conjunction with a gas chromatograph, and is mainly used for solid phase microextraction rods, solid phase microextraction stirring rods, bundled capillary solid The thermal desorption of phase microextraction tube and packed adsorption column can quickly desorb the adsorbed and enriched trace components.

Background technique

Solid phase microextraction (SPME) is to absorb or absorb and dissolve the target components in the sample to the extraction stationary phase to achieve the purpose of enriching the target components. It is an important sample in the analysis of trace organic pollutants. preprocessing techniques. Due to the simple operation, no use of organic solvents, and good enrichment effect, this technology has been developed rapidly. Solid-phase microextraction technology is generally used in conjunction with gas chromatography. The analyte is desorbed from the extraction phase by thermal desorption, and the desorbed carrier gas is used to introduce the desorbed analyte into the gas chromatographic column for analysis. Since the enriched target components can completely enter the gas chromatograph for detection, the sensitivity of the analysis method is greatly improved. The desorption of the fiber needle solid phase microextraction can be completed directly in the gas chromatograph injector, thus avoiding the use of a special thermal desorption device. Other solid-phase microextractors such as solid-phase microextraction sticks, solid-phase microextraction stirring rods, bundled capillary solid-phase microextraction tubes, and packed adsorption columns require special thermal desorption devices to complete desorption and chromatographic sampling.

In the prior art, the device for solid state adsorption stir bar thermal desorber (Chinese patent: ZL200410046349.5) can completely desorb components with boiling point T _bp slightly lower than thermal desorption temperature T. In this patented design, there is a cold zone between the outlet of the inner liner tube and the area A of the sample transfer tube, and the area B between the sample transfer tube and the chromatographic injector, so that the thermally desorbed high-boiling components are in A and B Carryover in both regions reduces sample recovery and desorption repeatability, and components with boiling points above the thermal desorption temperature cannot be distilled. At the same time, there is no fixed connection design between the desorber and the gas chromatographic sampler, and the fixation of the desorber requires external equipment to assist in the fixation during use. In addition, the desorption carrier gas is introduced from the pressure cap of the inner liner, which is very inconvenient to use.

Contents of the invention

In order to overcome the design defects in the prior patent technology, the present invention provides a thermal desorption device. In this device, the area A between the liner outlet and the sample transfer tube is heated by the heating tube and the desorbing carrier gas, and is insulated by thermal insulation material to eliminate the cold spot in the A area, and the sample transfer tube leads out to the part B of the thermal desorber Heated by heat conduction from the upper cap of the gas chromatograph injector. The above design eliminates the cold area of the sample transmission flow path, greatly reduces the residue of sample components, improves thermal desorption efficiency, and saves heating energy at the same time.

In order to achieve the above purpose, a thermal desorption device provided by the present invention includes a heating tube, a heating wire, an outer sleeve, an inner liner, an inner liner pressure head, a desorber upper cover, an inner liner pressure cap, an inner liner Tube base, liner tube base heat insulation ring, sample transfer tube fastening pressure cap, sample transfer tube, desorber base, desorption purge gas path and desorption split gas path, characterized in that:

The heating tube, the outer sleeve and the inner tube are all hollow cylindrical structures with openings at the upper and lower ends, and are arranged coaxially; the outer wall of the heating tube is wound with a heating wire, and the heating tube is placed inside the outer sleeve. The sleeve is used to protect the heating tube, and the inner liner is placed in the heating tube; the upper opening of the outer sleeve is provided with a desorber upper cover, and the lower opening is provided with a resolver base;

A liner pipe pressure head is provided at the upper opening of the liner pipe, a groove is provided at the lower end of the liner pipe pressure head, and an annular groove is radially provided on the side wall of the groove, and a first Sealing ring; the upper end of the lining pipe protrudes from the heating tube, passes through the first sealing ring and is placed in the groove at the lower end of the lining pipe pressure head, and the inner cavity of the lining pipe pressure head and the heating pipe is sealed by the first sealing ring. ring seal; the outer wall surface of the upper end of the liner pipe indenter is provided with an annular protrusion along the radial direction to form a first-stage annular step, and the outer wall surface of the lower end of the liner pipe indenter is radially inwardly recessed to form a second-stage annular step. The second sealing ring and the third sealing ring are respectively placed on the first-level annular step and the second-level annular step. An annular groove is arranged radially in the middle of the two-level steps, and a through hole is arranged on the annular groove as the first small The hole leads to the groove at the lower end of the liner pressure head;

The upper cover of the desorber is a cylinder, the inner wall surface of the upper end is radially recessed to form a first-stage annular step, and the inner wall surface of the lower end is provided with an annular protrusion along the radial direction to form a second-stage annular step. There is an internal thread on the inner wall of the upper cover of the desorber, and a through hole is provided between the first-stage annular step and the second-stage annular step as an analytical purge gas path; the pressure head of the inner liner is placed in the upper cover of the desorber, The pressure head of the liner and the upper cover of the desorber are connected through two steps respectively arranged on them, and the analysis purge gas path is connected with the annular groove in the middle of the two steps of the pressure head of the liner; the desorption purge gas is routed through the liner The first small hole of the pressure head enters and communicates with the inner cavity of the inner liner; the upper opening of the desorber upper cover is provided with a liner pressure cap with external threads, and the inner thread on the inner wall of the upper end of the desorber is connected to the inner The external threads on the outer periphery of the liner pressure cap are screwed together, and the two can be screwed and fixed to press the second sealing ring and the third sealing ring outside the liner pressure head, so that the upper cover of the desorber and the liner are pressed. sealed between the heads;

The insulating ring of the lining pipe base is a hollow cylindrical structure with openings at the upper and lower ends, and the lining pipe base is arranged inside; the upper end of the lining pipe base is provided with a groove, and a Annular groove, the fourth sealing ring is arranged in the annular groove, the lower end of the lining pipe protrudes from the heating pipe, passes through the fourth sealing ring and is placed in the upper groove of the lining pipe base, the lining pipe base and the heating pipe The inner cavity of the tube is sealed by the fourth sealing ring; there is a through hole on the side wall surface of the lower part of the groove at the upper end of the liner tube base, which is used as a desorption shunt gas path; the lower end of the liner tube base is provided with a groove with an internal thread, There is a through hole between the upper groove and the lower groove of the tube base;

There is a through hole at the central axis of the fastening cap of the sample transmission tube with external threads, and the base of the inner liner is screwed with the thread on the fastening cap of the sample transmission tube; the upper end of the sample transmission tube passes through the sample transmission tube. The tube is fastened to the pressure cap, and then the capillary ferrule is installed on the outer surface, and then extended into the through hole of the liner base, the sample transmission tube is connected with the inner cavity of the liner tube; the lower end of the sample transmission tube passes through the injection pad It is connected with the gas chromatography sampler; the lower end of the fastening pressure cap of the sample transmission tube is provided with a groove, and the groove of the fastening pressure cap of the sample transmission tube is buckled on the nut of the gas chromatography sampler; the nut is used for Compress the sampling pad;

The base of the desorber is a hollow airtight container, the upper and lower ends of the airtight container are provided with openings, the lower end of the outer sleeve and the heat insulating ring of the inner liner base are inserted into the base of the desorber through the upper and lower openings of the airtight container.

In the thermal desorption device, the heat-insulating ring of the liner base is made of high-temperature-resistant and heat-insulating materials, which can be high-temperature-resistant polymer materials or ceramics, and high-temperature-resistant polymer materials such as bakelite, polytetrafluoroethylene, etc. Vinyl, PEEK, PESK or polyimide.

In the thermal desorption device, a thermocouple is provided on the outer wall of the heating tube, and the thermocouple and the heating wire are connected to a temperature controller through wires.

In the thermal desorption device, the heating tube, the outer sleeve, the pressure head of the lining tube, the upper cover of the resolver, the pressure cap of the lining tube, the base of the lining tube, and the fastening pressure cap of the sample transmission tube are made of stainless steel. or other metal materials.

In the thermal desorption device, the inner liner is a quartz or glass tube closed at the lower end.

In the thermal desorption device, the sample transmission tube is a quartz capillary with a polyimide protective coating or a stainless steel capillary with a deactivated inner wall.

When using the above-mentioned device for thermal desorption, start the temperature controller to heat the heating tube, and the components in the liner tube will be heated and desorbed. The desorption purge gas enters the liner from the first small hole in the pressure head of the liner, and carries the desorbed components through the sample transfer tube into the gas chromatography for separation and analysis; the desorption split gas path is used to remove the desorbed components when necessary. Part of the components are discharged from the desorber to prevent the overload of the gas chromatographic analysis column.

During the process of thermally desorbed sample component vapor passing through the sample transfer tube into the gas chromatograph injector, if the temperature of the sample transfer tube is much lower than that of the inner lining tube, it will cause some component vapors to condense inside the sample transfer tube , unable to enter the gas chromatograph injector, resulting in desorption residues. For components with higher boiling points, the residual phenomenon is more serious. In the above device, the base of the inner liner can be kept at a relatively high temperature through the heat conduction of the heating tube; at the same time, the fastening pressure cap of the sample transmission tube can be maintained at a relatively high temperature through the heat conduction of the upper cap of the gas chromatograph injector. In this way, the sample transfer tube can be heated by the liner base and the fastening cap of the sample transfer tube, and insulated by the heat insulation ring of the liner base to keep it at a higher temperature, effectively eliminating the cold zone and avoiding comprehension. Absorbed components condense in the sample transfer tube, causing desorbed residues. For the desorption of high boiling point components, the effect is very significant.

In the existing technology (Chinese patent: ZL200410046349.5), the outer periphery of the sample transmission tube is covered with a metal capillary for heat conduction and heating of the sample transmission tube, but the heat capacity of the metal capillary is small and the heat dissipation is fast, so it cannot play a good role Heating and insulation effect.

The thermal desorption device of the present invention has the following advantages:

1. The device is small in size and easy to fix. It does not need external equipment to fix it when using it, and the operation is simpler and more convenient.

2. The heating speed is fast, the temperature control error is small, and the power consumption is low.

3. There is no cold zone in the sample transfer process, and there is no residue in the desorption, which improves the sensitivity and accuracy of the analysis.

4. It has the function of thermal desorption split injection, which effectively prevents the overload of the analytical column and improves the chromatographic separation efficiency.

5. It has a wide range of applications and can be used for pretreatment of environmental samples, biological samples, food, beverages and other samples.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention, constitute a part of the application, and do not constitute an improper limitation of the present invention. In the accompanying drawings:

Fig. 1 is the structural representation of thermal desorption device of the present invention, wherein 1. heating tube, 2. heating wire, 3. outer sleeve, 4. liner tube, 5. liner tube pressure head, 6. desorber upper cover , 7. Liner pressure cap, 8. Liner base, 9. Liner base insulation ring, 10. Sample transfer tube fastening cap, 11. Sample transfer tube, 12. Desorber base, 13. Desorption Purge gas path, 14. Desorption split gas path, 15. First sealing ring, 16. Second sealing ring, 17. Third sealing ring, 18. First small hole, 19. Fourth sealing ring, 20. Capillary Cartridge, 21. SPME rod, 11A. Sample transfer tube area A, 11B. Sample transfer tube area B.

Fig. 2 is the chromatographic analysis comparison chart of Application Example 1, wherein A is the chromatogram of thermal desorption using the device described in Example 1, and B is the chromatogram of thermal desorption when the liner base heat insulating ring is replaced by stainless steel .

Fig. 3 is the chromatogram of application example 2, wherein A is the chromatogram of desorption for the first time after extraction, and B is the chromatogram of desorption for the second time. The peaks in the figure are: 1. phenanthrene, 2. anthracene, 3. fluoranthene, 4. pyrene.

Fig. 4 is the chromatogram of application example 3. The peaks in the figure are: 1. phenol, 2.2-chlorophenol, 3.2,6-xylenol, 4.2-nitrophenol, 5.2,4-dichlorophenol, 6.2,4,6-trichlorophenol.

detailed description

The present invention will be described below in conjunction with the embodiments and accompanying drawings, where the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but not as a limitation to the present invention.

Example 1

As shown in Figure 1, a thermal desorption device consists of a heating tube 1, a heating wire 2, an outer sleeve 3, an inner liner 4, an inner liner pressure head 5, a desorber upper cover 6, and an inner liner pressure cap 7. Lining tube base 8, lining tube base heat insulation ring 9, sample transfer tube fastening cap 10, sample transfer tube 11, desorber base 12, desorption purge gas path 13, desorption split gas path 14, and temperature The control element is composed of, characterized in that:

The heating tube 1, the outer sleeve 3 and the inner liner tube 4 are all hollow cylindrical structures with openings at the upper and lower ends, and are arranged coaxially; the outer wall of the heating tube 1 is wound with a heating wire 2 and equipped with a thermocouple , the thermocouple and the heating wire 2 are connected to a temperature controller through wires; the heating tube 1 is placed inside the outer sleeve 3, and the outer sleeve 3 is used to protect the heating tube 1, and the inner lining tube 4 is placed in the heating tube 1; The liner 4 is a quartz tube with a reduced inner diameter at the lower end, and has a built-in solid-phase microextraction rod 21 that requires thermal desorption; the upper opening of the outer sleeve 3 is provided with a desorber upper cover 6, and the lower opening is provided with a resolver base 12;

A liner pipe pressure head 5 is provided at the upper opening of the liner pipe 4, a groove is provided at the lower end of the liner pipe pressure head 5, and an annular groove is radially provided on the side wall of the groove. There is a first sealing ring 15; the upper end of the lining pipe 4 protrudes from the heating tube 1, passes through the first sealing ring 15 and is placed in the lower end groove of the lining pipe pressure head 5, and the lining pipe pressure head 5 and the heating The inner cavity of the pipe 1 is sealed by the first sealing ring 15; Recessed radially inward to form a second-level annular step, the second sealing ring 16 and the third sealing ring 17 are placed on the first-level annular step and the second-level annular step, respectively, and a ring-shaped ring is arranged radially between the two steps. groove, the annular groove is provided with a through hole, which leads to the lower end groove of the liner head 5 as the first small hole 18;

The upper cover 6 of the desorber is a cylinder, the inner wall surface of the upper end is radially recessed to form a first-stage annular step, and the inner wall surface of the lower end is radially provided with annular protrusions to form a second-stage annular step, above the first-stage annular step The upper cover 6 of the desorber is provided with an internal thread on the inner wall surface, and a through hole is provided between the first-stage annular step and the second-stage annular step as the analytical purge gas path 13; the inner liner head 5 is placed in the desorber In the upper cover 6, the liner head 5 and the desorber upper cover 6 are connected through two steps respectively arranged on them, and the analytical purge gas path 13 communicates with the annular groove in the middle of the two steps of the liner head 5 The desorption purge gas path 13 enters through the first small hole 18 of the liner head 5 and communicates with the inner cavity of the liner 4; the upper opening of the desorber upper cover 6 is provided with an inner liner with an external thread The pipe pressure cap 7, the internal thread on the inner wall of the upper end of the desorber upper cover 6 is screwed with the external thread on the outer periphery of the liner pipe pressure cap 7, and the two can be screwed and fixed to compress the second outside of the liner pipe pressure head 5. The sealing ring 16 and the third sealing ring 17, whereby the desorber upper cover 6 and the liner pressure head 5 are sealed;

The inner liner base heat insulation ring 9 is a hollow cylindrical bakelite with openings at both ends of the upper and lower ends, and the inner liner base 8 is arranged inside; the upper end of the inner liner base 8 is provided with a groove, An annular groove is arranged in the radial direction, and a fourth sealing ring 19 is arranged in the annular groove. The lower end of the lining pipe 4 protrudes from the heating tube 1 and is placed on the upper end of the lining pipe base 8 through the fourth sealing ring 19 In the groove, the fourth sealing ring 19 is sealed between the inner lining tube base 8 and the inner cavity of the heating tube 1; a through hole is provided on the side wall surface of the lower part of the groove at the upper end of the inner lining tube base 8, as a desorption shunt gas path 14; The lower end of the lining pipe base 8 is provided with a groove with an internal thread, and a through hole is provided between the upper end groove and the lower end groove of the inner lining pipe base 8;

There is a through hole at the central axis of the sample transmission tube fastening cap 10 with external threads, and the inner liner base 8 is screwed with the sample transmission tube fastening cap 10 through the threads on it; the upper end of the sample transmission tube 11 Fasten the pressure cap 10 through the sample transmission tube, and then cover it with a capillary ferrule 20 and then extend into the through hole of the liner tube base 8. The sample transmission tube 11 communicates with the inner cavity of the liner tube 4; the sample The lower end of the transfer tube 11 passes through the sample pad and communicates with the gas chromatograph injector; the lower end of the sample transfer tube fastening cap 10 is provided with a groove, and the groove of the sample transfer tube fastening cap 10 is buckled in the gas chromatograph. On the nut of the injector; the nut is used to compress the injection pad;

The base 12 of the desorber is a hollow airtight container, and the upper and lower ends of the airtight container are provided with openings. The lower end of the outer sleeve 3 and the heat insulating ring 9 of the inner liner base are inserted on the base 12 of the desorber through the openings at the upper and lower ends of the airtight container. Inside.

Among them, the heating tube 1, the outer sleeve 3, the pressure head of the liner tube 5, the upper cover of the resolver 6, the pressure cap of the liner tube 7, the base of the liner tube 8, and the fastening pressure cap 10 of the sample transmission tube are all made of stainless steel. The sample transfer tube 11 is a quartz capillary with an inner diameter of 0.10 mm and a polyimide protective coating.

Application example 1

The thermal desorption device described in Example 1 was used, nitrogen was used as the desorption purge gas, the size of the air flow was adjusted, and the desorption split flow path was closed. A retention spacer pre-column is connected in front of the gas chromatographic analysis column. The temperature controller is started to heat the heating tube 1, and the substances desorbed from the solid phase microextractor 21 are carried by the desorption purge gas through the sample transmission tube 11 into the gas chromatograph for separation and analysis. The solid-phase microextraction rod is coated with polydimethylsiloxane as the stationary phase, and the film thickness is 60 μm. After extracting the hexachlorobenzene standard sample with a concentration of 800 μg/L in a 15 mL water sample for 30 minutes, put it into the liner tube Carry out thermal desorption, the obtained chromatogram is Fig. 2A. After changing the insulating ring of the liner base to stainless steel, the chromatogram obtained under the same conditions is shown in Figure 2B.

The desorption condition of Fig. 2A is:

Spectrum 1. Desorption for the first time (280°C, 5min), Spectrum 2. Desorption for the second time (280°C, 5min); Solution of Figure 2B

The suction condition is:

Spectrum 1. The first desorption (280°C, 5min), spectrum 2. The second desorption (280°C, 5min), spectrum 3. The third desorption (300°C, 5min), spectrum 4. The second Four times of desorption (300°C, 10min), spectrum 5. The fifth time of desorption (280°C, 5min).

It can be seen from the figure that for the hexachlorobenzene with a boiling point of 325°C, the thermal desorption device using the heat insulating ring of the liner base can be completely desorbed once, and the thermal desorption device that replaces the heat insulating ring of the liner base with stainless steel The suction device needs to desorb four times to basically desorb completely. From the comparison chart, it can be seen that the insulation effect of the heat insulation ring of the liner base effectively eliminates the cold zone and improves the thermal desorption efficiency.

Application example 2

The thermal desorption device described in Example 1 was used to perform thermal desorption on the solid phase microextraction rod. The solid-phase microextraction rod is coated with polydimethylsiloxane as the stationary phase, and the film thickness is 60 μm. After extracting the standard sample of polycyclic aromatic hydrocarbons with a concentration of 20 μg/L in a 15 mL water sample for 30 minutes, put it into the liner tube Perform thermal desorption. The boiling points of the components are: phenanthrene (340°C), anthracene (340°C), fluoranthene (375°C), and 4.pyrene (404°C). The desorption conditions are: rise from 40°C to 280°C within 1.5 minutes for desorption for 5 minutes, the desorption purge gas is nitrogen, the flow rate is 3mL/min, and the desorption split gas path is closed. After the analysis was completed, the second thermal desorption was performed to check the residual situation of the first thermal desorption, and the analysis spectrum is shown in Figure 3. The results show that the thermal desorption device has a one-time desorption residue of less than 0.1% for components with a boiling point as high as 404°C.

Application example 3

The thermal desorption device described in Example 1 was used to perform thermal desorption on the solid phase microextraction rod. The solid phase microextraction rod is coated with polyether sulfone ketone as the stationary phase, and the film thickness is 60 μm. After extracting the phenolic standard sample with a concentration of 200 μg/L in 15 mL of water sample for 30 minutes, put it into the liner tube for thermal desorption. . The desorption conditions are as follows: within 1.5 minutes from 40°C to 250°C for 3 minutes, the desorption purge gas is nitrogen, the flow rate is 3mL/min, and the desorption split flow path is closed. The analysis spectrum is shown in Figure 4.

Application example 4

The thermal desorption device described in Example 1 was used to perform thermal desorption on the solid phase microextraction rod. The solid-phase microextraction rod is coated with polydimethylsiloxane as a stationary phase with a film thickness of 60 μm. After extracting organophosphorus pesticides in 15 mL of fruit juice for 60 minutes, it is placed in a liner tube for thermal desorption. The desorption conditions are: rise from 40°C to 260°C within 1.5 minutes for desorption for 5 minutes, the desorption purge gas is nitrogen, the flow rate is 3mL/min, and the desorption split gas path is closed.

Example 5

The thermal desorption device described in Example 1 was used to perform thermal desorption on the solid phase microextraction rod. Use helium as the desorption purge gas, adjust the flow rate to 3mL/min, open the desorption split gas path, and adjust the split ratio to 5:1. The solid-phase microextraction rod is coated with polydimethylsiloxane as a stationary phase with a film thickness of 70 μm. After extracting organochlorine pesticides in 20 mL of milk for 30 minutes, put it into a liner tube and insert it into a thermal desorption device for thermal extraction. Desorption. The desorption conditions are as follows: within 1.5 minutes, the temperature rises from 40°C to 300°C for 5 minutes. Gas chromatography was detected by electron capture detector (ECD), and the lower limit of detection was 0.2ng/L.

Application example 6

Thermal desorption device as described in Example 1. The lining tube is replaced by a bundled capillary solid-phase microextraction tube. The stationary phase coated in the bundled capillary solid-phase microextraction tube is phenyl-modified polydimethylsiloxane with a film thickness of 7 μm. After 1.5 minutes of extraction of a chlorobenzene standard sample with a concentration of 1 μg/L in a 250 mL water sample, Put into thermal desorption device for thermal desorption. The desorption conditions are: rise from 40°C to 260°C within 1.5 minutes and desorb for 4 minutes, the desorption purge gas is nitrogen, the flow rate is 3mL/min, and the desorption split gas path is closed. The results of gas chromatography analysis show that the thermal desorption efficiency of the thermal desorption device for the components adsorbed and enriched by the bundled capillary solid-phase microextraction tube is as high as 99% (boiling point ≤ 300°C).

Application example 7

Thermal desorption device as described in Example 1. The liner tube is filled with graphitized carbon black and carbon molecular sieve as a packed adsorption column, and the volatile organic compounds in the air are extracted for 10 minutes at a speed of 200mL/min by an aspirator, and then put into a heating tube for thermal desorption. The desorption conditions are: rise from 40°C to 300°C within 1.5 minutes and desorb for 10 minutes, the desorption purge gas is helium, the flow rate is 4mL/min, and the desorption split gas path is closed. The gas chromatography analysis results show that the thermal desorption device has a high thermal desorption efficiency to the adsorption column.

Claims (6)

1. A thermal desorption device, comprising heating tube (1), heating wire (2), outer sleeve (3), liner tube (4), liner tube pressure head (5), desorber loam cake ( 6), liner cap (7), liner base (8), liner base insulation ring (9), sample transfer tube fastening cap (10), sample transfer tube (11), desorber The base (12), the desorption purge gas path (13) and the desorption shunt gas path (14), are characterized in that: The heating pipe (1), the outer sleeve (3) and the lining pipe (4) are all hollow cylindrical structures with openings at the upper and lower ends, and are coaxially arranged; the outer wall of the heating pipe (1) is wound with a heating The wire (2), the heating tube (1) is placed inside the outer sleeve (3), the outer sleeve (3) is used to protect the heating tube (1), and the inner liner tube (4) is placed in the heating tube (1); A desorber upper cover (6) is provided at the upper opening of the outer sleeve (3), and a resolver base (12) is provided at the lower opening; A lining pipe pressure head (5) is provided at the opening of the upper end of the lining pipe (4), a groove is provided at the lower end of the lining pipe pressure head (5), and an annular groove is radially provided on the side wall of the groove , the annular groove is provided with a first sealing ring (15); the upper end of the lining pipe (4) protrudes from the heating tube (1), passes through the first sealing ring (15) and is placed on the lining pipe pressure head ( 5) in the groove at the lower end, the first sealing ring (15) is used to seal the inner cavity between the lining pipe pressure head (5) and the heating pipe (1); the upper outer wall surface of the lining pipe pressure head (5) is along the An annular protrusion is provided in the radial direction to form a first-stage annular step, and the outer wall surface of the lower end of the liner pipe indenter (5) is radially inwardly recessed to form a second-stage annular step. The second sealing ring (16) and the third sealing ring (17) are respectively placed on the steps, an annular groove is arranged radially in the middle of the two steps, and a through hole is arranged on the annular groove as the first small hole (18) Lead to the lower end groove of the liner pressure head (5); The upper cover (6) of the desorber is a cylinder, the inner wall surface of the upper end is radially recessed to form a first-stage annular step, and the inner wall surface of the lower end is provided with an annular protrusion along the radial direction to form a second-stage annular step. The upper cover (6) of the desorber above the step is provided with an internal thread on the inner wall surface, and a through hole is provided between the first-stage annular step and the second-stage annular step as an analytical purge gas path (13); The head (5) is placed in the upper cover (6) of the desorber, and the liner pressure head (5) and the upper cover (6) of the desorber are connected through two steps respectively arranged on them, and the analysis of the purge gas path (13) and The annular groove in the middle of the two steps of the liner head (5) is connected; the desorption purge gas path (13) enters through the first small hole (18) of the liner head (5), and The inner cavity of (4) is connected; the upper opening of the upper end of the desorber upper cover (6) is provided with an inner liner pressure cap (7) with external threads, and the inner thread of the inner wall of the upper end of the desorber upper cover (6) and the inner lining The external threads on the outer periphery of the pipe pressure cap (7) are screwed together, and the two can be screwed and fixed to compress the second sealing ring (16) and the third sealing ring (17) outside the lining pipe pressure head (5), Get sealing between desorber loam cake (6) and liner pressure head (5) by this; The liner base heat insulation ring (9) is a hollow cylindrical structure with upper and lower ends open, with a liner base (8) inside; the upper end of the liner base (8) is provided with a groove, An annular groove is arranged radially on the side wall of the groove, and a fourth sealing ring (19) is arranged in the annular groove, and the lower end of the lining pipe (4) protrudes from the heating pipe (1) and passes through the fourth sealing The ring (19) is placed in the upper end groove of the liner tube base (8), and the fourth sealing ring (19) is used to seal between the liner tube base (8) and the inner cavity of the heating tube (1); A through hole is provided on the lower side wall of the groove at the upper end of the base (8) as a desorption shunt air path (14); the lower end of the inner liner base (8) is provided with a groove with an internal thread, and the upper end of the inner liner base (8) A through hole is provided between the groove and the lower groove; A through hole is provided at the central axis of the sample transmission tube fastening cap (10) with external threads, and the inner liner base (8) is screwed with the sample transmission tube fastening cap (10) through the thread on it; The upper end of the sample transfer tube (11) passes through the sample transfer tube to fasten the pressure cap (10), and then sets the capillary ferrule (20) outside it, and then extends into the through hole of the inner liner tube base (8). The tube (11) communicates with the inner chamber of the liner tube (4); the lower end of the sample transfer tube (11) passes through the sample pad and communicates with the gas chromatograph injector; the sample transfer tube fastens the pressure cap (10) The lower end is provided with a groove, and the groove buckle of the fastening pressure cap (10) of the sample transfer tube is placed on the nut of the gas chromatographic sample injector; the nut is used to compress the sampling pad; The base of the desorber (12) is a hollow airtight container, and the upper and lower ends of the airtight container are provided with openings, and the lower end of the outer sleeve (3) and the heat insulating ring (9) of the inner liner base pass through the openings at the upper and lower ends of the airtight container. Set in the desorber base (12). 2. The thermal desorption device according to claim 1, characterized in that: The heat-insulating ring (9) of the liner base is made of high-temperature-resistant and heat-insulating materials, which are high-temperature-resistant polymer materials or ceramics. The high-temperature-resistant polymer materials are bakelite, polytetrafluoroethylene, polyether ether ketone, Polyethersulfoneketone or polyimide. 3. The thermal desorption device according to claim 1, characterized in that: A thermocouple is arranged on the outer wall of the heating tube (1), and the thermocouple and the heating wire (2) are connected to a temperature controller through wires. 4. The thermal desorption device according to claim 1, characterized in that: The heating tube (1), the outer sleeve (3), the inner tube pressure head (5), the upper cover of the resolver (6), the inner tube pressure cap (7), the inner tube base (8), the sample The fastening pressure cap (10) of the transmission pipe is made of stainless steel or other metal materials. 5. The thermal desorption device according to claim 1, characterized in that: The inner liner (4) is a quartz or glass tube closed at the lower end. 6. The thermal desorption device according to claim 1, characterized in that: The sample transmission tube (11) is a quartz capillary with a polyimide protective coating or a stainless steel capillary whose inner wall has undergone deactivation treatment.