CN116539782A - Sweeping and trapping device with high trapping efficiency and high component sensitivity - Google Patents

Abstract

The scheme belongs to the technical field of analytical instruments, and discloses a sweeping and trapping device with high trapping efficiency and high component sensitivity. The purging and trapping device is used for being combined with an analysis mechanism with an analysis column and comprises a purging mechanism and a trapping mechanism, wherein the purging mechanism is used for accommodating a sample to be tested and purging components to be tested in the sample to the trapping mechanism by means of first gas, and the trapping mechanism is used for adsorbing and then desorbing the components to be tested and distributing the components to be tested to the analysis column by means of second gas; the device is characterized in that the trapping mechanism comprises a trapping pipe, the trapping pipe is an inerting empty pipe with the trapping temperature of minus 180 ℃ to minus 130 ℃ and the inner diameter of 1-2 mm, the first end of the trapping pipe is communicated with the purging mechanism in the adsorption stage, the first end of the trapping pipe is communicated with the analysis column through a transmission line in the desorption stage, and the second end of the trapping pipe is communicated with the second gas inlet; the transmission line is a capillary tube with the inner diameter of 0.20-0.35 mm, and the second gas completely transmits the components to be tested to the analysis column, so that the problem that the high trapping efficiency and the high component sensitivity can not be combined is solved.

Description

Sweeping and trapping device with high trapping efficiency and high component sensitivity

Technical Field

The scheme belongs to the technical field of analytical instruments, and particularly relates to a sweeping and trapping device with high trapping efficiency and high component sensitivity.

Background

The content of volatile organic compounds in the environmental water body is low, the direct determination of the volatile organic compounds is extremely difficult, and a proper sample pretreatment method is required to be selected for separation and enrichment, so that the detection limit of an analysis instrument is reached. The method has the advantages of less sampling amount, high enrichment efficiency, small interference by a matrix, easy realization of on-line detection and the like, and is commonly used for measuring volatile and semi-volatile organic matters in water, soil and atmosphere after being combined with GC/GC-MS.

The principle of the Purge and Trap technology (P & T) is that a sample (liquid or solid) to be tested is placed in a sealable container (a sample bottle or a Purge tube), inert gas is used for introducing the sample into the liquid (or the solid surface) for a certain time at a certain temperature and flow rate, and the components to be analyzed are purged out and are concentrated (trapped) by an adsorption tube (Trap) filled with an adsorption material; after the purge and trap process is completed, the adsorbed components are desorbed by rapidly heating the adsorption tube (trap) and carried into the GC/GC-MS with carrier gas for analysis.

The trap is mainly a trap with filler, which is recommended to be used in the HJ639-2012 method, is a C-trap, wherein the trap contains 1/3Tenax,1/3 silica gel and 1/3 active carbon, and the trap with the composite filler has high trap efficiency, multiple trap types and simple structure. In order to improve the trapping efficiency of the target component, the trapping trap is usually provided with a larger volume (more filler is convenient to mount) by increasing the purging time and the filler consumption (the target component is prevented from penetrating), and during the subsequent desorption, one path of high-flow gas is required to be introduced into the trapping trap (a carrier gas main path from a GC sample inlet generally), and the enriched target component is injected into the chromatographic analysis column in a small amount (the splitting ratio is generally 30:1) by setting the splitting ratio, so that the detection limit of the trace component is seriously influenced, and the peak broadening is further aggravated due to the volume of the trapping trap and the volume of the sample inlet.

In addition, this type of trapping has several problems: 1. for a newly installed filler trap, a longer time of aging is required to obtain a lower background baseline; 2. after analyzing the high-concentration sample, partial components are incompletely desorbed on the trap, so that residues exist to a certain extent, and the subsequent analysis of the low-concentration sample is greatly interfered; 3. the filler in the trap has a certain service life, the trap needs to be replaced periodically when the trap is used for a long time, and for analyzing complex and unknown samples, part of unknown components can cause irreversible influence on the filler in the trap, so that the service life of the trap is shortened; 4. for an electrically heated filler trap, uneven heating and temperature overshoot can cause the temperature of a part of the region to exceed the upper limit of the use temperature of the filler, thereby causing permanent damage to the filler.

Disclosure of Invention

The scheme aims at overcoming at least one defect (deficiency) in the prior art and providing the purging and trapping device with high trapping efficiency and high component sensitivity.

In order to solve the technical problems, the following technical scheme is adopted:

the purging and trapping device is used for being combined with an analysis mechanism with an analysis column and comprises a purging mechanism and a trapping mechanism, wherein the purging mechanism is used for accommodating a sample to be tested and purging components to be tested in the sample to the trapping mechanism by means of first gas, and the trapping mechanism is used for adsorbing and then desorbing the components to be tested and distributing the components to be tested to the analysis column by means of second gas; the device is characterized in that the trapping mechanism comprises a trapping pipe, the trapping pipe is an inerting empty pipe with the trapping temperature of minus 180 ℃ to minus 130 ℃ and the inner diameter of 1-2 mm, the first end of the trapping pipe is communicated with the purging mechanism in the adsorption stage, the first end of the trapping pipe is communicated with the analysis column through a transmission line in the desorption stage, and the second end of the trapping pipe is communicated with the second gas inlet; the transmission line is a capillary tube with an inner diameter of 0.20-0.35 mm, and the second gas is used for conveying all components to be tested to the analysis column.

According to the scheme, the inerting hollow pipe with the small inner diameter is adopted as the collecting pipe, and meanwhile, the capillary pipe with the small inner diameter is adopted as the transmission line between the purging and collecting instrument and the gas chromatograph, so that the purging and collecting device can keep high collecting efficiency, and meanwhile, components to be tested can be sent into the analysis column in a non-split sample injection mode, so that the sensitivity of the components is improved, and the problem that the high collecting efficiency and the high sensitivity of the components cannot be combined is solved. In addition, the inert hollow tube is used as a collecting tube, so that irreversible adsorption of partial polar compounds by the filler can be avoided, and the sample analysis range is enlarged. Preferably, the collection tube is an inerted stainless steel hollow tube and the transmission line is a stainless steel passivated capillary tube.

The trapping mechanism preferably comprises a first two-position six-way valve through which the trapping tube communicates with the purge mechanism, the transmission line and the second gas inlet to control the flow path direction, determining whether the trapping mechanism is in the adsorption stage or the desorption stage.

The purging and trapping device preferably comprises a filtering mechanism, wherein the filtering mechanism comprises a pre-column, the pre-column is a capillary column with the working temperature of 180-220 ℃, the first end of the pre-column is communicated with the transmission line, the second end of the pre-column is communicated with the analysis column and is used for filtering out part of components in the components to be tested before the components to be tested enter the analysis column, so that the analysis column is prevented from being polluted by high-concentration components or other components, and the service life of the analysis column is reduced. The pre-column is preferably a 624 capillary column of 2m 0.25mm 1.4um, preferably placed in a thermostatted oven to maintain the operating temperature. The oven preferably has a temperature regulation function to age the pre-column by increasing the temperature after the end of the operation.

The filtering mechanism preferably comprises a second two-position six-way valve, and the pre-column is communicated with the transmission line and the analysis column through the second two-position six-way valve so as to realize the switching of the pre-column and determine whether the desorbed component to be detected passes through the pre-column.

The purge-and-trap device preferably includes a gas source providing a first gas, the gas source being in communication with the gas inlet of the purge mechanism during the adsorption phase, with the first end of the collection tube and/or the second end of the pre-column during the evacuation phase, and the second end of the collection tube and/or the first end of the pre-column being in communication with the outside during the evacuation phase.

The analysis mechanism is a gas chromatograph or a gas chromatograph-mass spectrometer, and the second gas inlet is provided by a chromatographic sample inlet so as to utilize chromatographic carrier gas as the second gas to distribute the desorbed component to be analyzed to the analysis column. The chromatographic sample inlet is connected with the trapping mechanism through a capillary hollow pipe, one end of the capillary hollow pipe is communicated with the bottom of the chromatographic sample inlet, and the other end of the capillary hollow pipe is communicated with the first end of the trapping pipe. The capillary hollow tube preferably has an inner diameter of 0.53mm and a length of 0.5 to 1m. The analytical column is preferably a 624 capillary column of 30m 0.25mm 1.4um placed in a temperature programmable column box.

Compared with the prior art, the scheme has the following beneficial effects: according to the scheme, the inerting hollow pipe with the small inner diameter is adopted as the collecting pipe, and meanwhile, the capillary pipe with the small inner diameter is adopted as the transmission line between the purging and collecting instrument and the gas chromatograph, so that the purging and collecting device can keep high collecting efficiency, and meanwhile, components to be tested can be sent into the analysis column in a non-split sample injection mode, so that the sensitivity of the components is improved, and the problem that the high collecting efficiency and the high sensitivity of the components cannot be combined is solved.

Drawings

The drawings are for illustrative purposes only and are not to be construed as limiting the present solution; for better illustration of the present solution, some parts of the figures may be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

Fig. 1 is a schematic structural diagram of a purge-trap device with a first two-position six-way valve in a desorption position and a second two-position six-way valve in a discharge position.

Fig. 2 is a schematic structural diagram of a purge-trap device with a first two-position six-way valve in an adsorption position and a second two-position six-way valve in a filtering position.

Figure 3 is a graph of the test for volatile organics in water 57 (two internal standards + three alternatives added).

Reference numerals illustrate: the device comprises an air source 110, a mass flowmeter 120, an injection pump 210, a six-position valve 211, an ultrapure water bottle 220, a water storage tank 230, a methanol bottle 240, a water sample bottle 250, a third two-position three-way valve 261, a purge pipe 310, an air inlet 311, an air outlet 312, a liquid inlet 313, a liquid outlet 314, a water removal pipe 320, a first two-position two-way valve 331, a first two-position three-way valve 332, a second two-position two-way valve 333, a trap 410, a transmission line 420, a second gas inlet 430, a first two-position six-way valve 441, a second two-position three-way valve 442, a pre-column 510, a second two-position six-way valve 521, an analysis column 610 and a waste liquid bottle 710.

Detailed Description

In order to better understand the present solution, a further detailed description of the present solution will be provided below in conjunction with specific embodiments.

Fig. 1-2 illustrate one embodiment of a purge-and-trap device. According to the embodiment, the inerting hollow tube with the small inner diameter is used as the collecting tube, and meanwhile, the capillary tube with the small inner diameter is used as the transmission line between the purging and collecting instrument and the gas chromatograph, so that the purging and collecting device can send components to be tested into the analysis column in a non-split sample injection mode while high collecting efficiency is maintained, and the component sensitivity is improved and the device can be used with an analysis mechanism with the analysis column.

Referring to fig. 1 to 2, the purging and trapping device comprises a purging mechanism and a trapping mechanism. Wherein the purge mechanism is used for accommodating a sample to be tested and purging components to be tested in the solution into the trapping mechanism by means of the first gas, and the trapping mechanism is used for trapping the components to be tested from the purge mechanism and delivering the trapped components to be tested to the analytical column 610 by means of the second gas. The first gas is provided by a gas source 110, and the gas source 110 can be part of a purge-and-trap device or an external mechanism. The second gas may be provided by a carrier gas of the combined analytical mechanism.

The trapping mechanism includes a trapping tube 410. The collecting pipe 410 is an inert empty pipe with the collecting temperature of minus 180 ℃ to minus 130 ℃ and the inner diameter of 1-2 mm and is used for adsorbing and then desorbing the components to be tested from the purging mechanism. The first end of the collection tube 410 is connected to the purge mechanism during the adsorption stage and to the analytical column 610 through the transfer line 420 during the desorption stage, wherein the transfer line 420 is a capillary tube having an inner diameter of 0.20-0.35 mm, and the second end of the collection tube 410 is connected to the second gas inlet 430. Therefore, the second gas can send all components to be tested (100% or nearly 100%) to the analysis column 610, so that no split sample injection is realized, the sensitivity of trace components and the detection limit of an instrument are improved, the high trapping efficiency is maintained, and the problem that the high trapping efficiency and the high component sensitivity cannot be combined is solved.

For this reason, we compared the test results of the present purge-trap device with the Tekmar purge-trap instrument on volatile organics in water 57 (two internal standards + three alternatives are added), as shown in fig. 3, where the black spectrum represents the test spectrum of 1ppb standard on the present purge-trap device, the red spectrum is the test spectrum of 10ppb standard on the Tekmar purge-trap instrument (split ratio 10:1), and the column flows for both sets of tests were 0.8ml/min. The figure shows that the response of the standard sample with the concentration of 1ppb on the purging and trapping device is higher than that of the standard sample with the concentration of 10ppb on the Tekmar purging and trapping device, which shows that the purging and trapping device can remarkably improve the response of the target component and reduce the detection limit of the device.

In addition, the use of inerted hollow tubes as manifold 410 also avoids irreversible adsorption of some polar compounds by the filler, and expands the sample analysis range. The inerting hollow tube is preferably an inerting stainless steel hollow tube with an inner diameter of 1/16 inch and a length of 10-15 cm, the temperature can be controlled by a direct electric heating mode, a thermocouple is welded on the outer wall of the collecting tube 410 through flame soldering for monitoring the temperature, a 6V alternating current transformer is used for passing, a solid state relay is connected between the collecting tube 410 and the transformer, and the temperature rising rate is regulated and controlled by regulating and controlling the duty ratio and PID parameters. The transmission line 420 is preferably a stainless steel passivated capillary with an inner diameter of 0.28mm and a length of 0.5-1 m and a maximum heating temperature of 250 ℃.

The trapping mechanism may also include a first two-position six-way valve 441. The collection tube 410 communicates with the purge mechanism, the transfer line 420 and the second gas inlet 430 through a first two-position six-way valve 441, the first two-position six-way valve 441 being used to control the flow direction, determining whether the collection mechanism is in the adsorption stage or the desorption stage. Specifically, the first two-position six-way valve 441 includes six ports in a clockwise annular array, which are a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port, respectively. Wherein the first interface is coupled to the transmission line 420, the second interface is coupled to the second gas inlet 430, the third interface is coupled to the second end of the manifold 410, the fourth interface is coupled to or acts as an evacuation port, the fifth interface is coupled to the purge mechanism, and the sixth interface is coupled to the first end of the manifold 410.

In the adsorption stage, the first two-position six-way valve 441 is in an adsorption position (the first interface is communicated with the second interface, the third interface is communicated with the fourth interface, and the fifth interface is communicated with the sixth interface, as shown in fig. 2), at this time, the first end of the trap pipe 410 is communicated with the purge mechanism, and the second end is communicated with the evacuation port, so as to continuously adsorb the component to be tested from the purge mechanism; and the second gas inlet 430 is directly connected to the transmission line 420 without affecting the adsorption process. In the desorption stage, the first two-position six-way valve 441 is in the desorption position (the second port is communicated with the third port, the fourth port is communicated with the fifth port, and the sixth port is communicated with the first port, as shown in fig. 1), at this time, the first end of the trap tube 410 is communicated with the transmission line 420, the second end is communicated with the second gas inlet 430, and the second gas distributes the desorbed component to be tested to the analytical column 610; the purging mechanism is directly communicated with the emptying port, and the desorption process is not influenced. The first two-position six-way valve 441 is preferably a pneumatic rotary valve that can withstand 250 c.

The purge mechanism may be configured to purge the tube 310. Purge tube 310 has a liquid inlet 313, an inlet 311, an outlet 312, and a liquid outlet 314. Wherein the liquid inlet 313 is used for injecting liquid, including but not limited to liquid sample to be measured. The gas inlet 311 is used for introducing a first gas, and may be connected to the gas source 110 through a first two-way valve 331, where the first two-way valve 331 is used for controlling on/off of the first gas. The air outlet 312 is connected to a fifth port of the first two-position six-way valve 441, so that the first gas carries the component to be tested into the trapping mechanism. The liquid drain 314 is used for draining the liquid in the purge tube 310, and can be communicated with a waste liquid bottle 710 for storing waste liquid through a second two-position two-way valve 333, and the second two-position two-way valve 333 is used for controlling the on-off of liquid drain. In the purging process, the first gas enters the purging pipe 310 from the gas inlet 311, the sample to be tested is purged, and the purged component to be tested enters the trapping mechanism along with the first gas through the gas outlet 312. It will be appreciated that the purge mechanism may also be configured as a sealable container such as a sample vial.

In order to avoid that the first gas introduced into the liquid sample to be tested brings moisture in the liquid sample to be tested into the capturing mechanism, a water removal pipe 320 may be arranged between the purging mechanism and the capturing mechanism. The water removal pipe 320 is preferably an inerted stainless steel pipe with an operating temperature of-40 ℃ to-30 ℃, an inner diameter of 1/8 inch and a length of 10-15 cm, the first end of the water removal pipe is communicated with the air outlet 312 of the purging pipe 310, and the second end of the water removal pipe is communicated with the fifth interface of the first two-position six-way valve 441. The temperature of the water removal pipe 320 can be controlled by a direct electric heating mode, a thermocouple is welded on the outer wall of the water removal pipe 320 through flame soldering and used for monitoring the temperature, a 6V alternating current transformer is used for passing through the water removal pipe 320, a solid relay is connected between the water removal pipe and the transformer, and the temperature rising rate is regulated and controlled by regulating and controlling the duty ratio and PID parameters.

The water removing pipe 320 and the purging pipe 310 can be communicated through a first two-position three-way valve 332, the first two-position three-way valve 332 is used for realizing switching of different air paths, a COM port of the first two-position three-way valve is connected with the first end of the water removing pipe 320, an NC port of the first two-position three-way valve is connected with the air outlet 312 of the purging pipe 310, and an NO port of the first two-position three-way valve can be communicated with the air source 110. When the COM port is communicated with the NC port, the first gas enters the water removal pipe 320 and the trapping mechanism through the purging pipe 310, so that the purging of the components to be tested is realized; when the COM port is communicated with the NO port, the first gas directly enters the water removing pipe 320 to realize the emptying of the water removing pipe 320, and if the first two-position six-way valve 441 is at the adsorption position, the first gas will continue to enter the collection pipe 410 to realize the emptying of the collection pipe 410.

Air source 110 may be in communication with air inlet 311, first two-position three-way valve 332, and an evacuation port of purge tube 310, respectively, via mass flow meter 120. The mass flowmeter 120, the evacuation port and the first two-position six-way valve 441 can be communicated through a second two-position three-way valve 442, the second two-position three-way valve 442 is used for realizing switching of different gas paths, a COM port of the second two-position three-way valve 442 is connected with a fourth port of the first two-position six-way valve 441, an NC port of the second two-position three-way valve 441 is connected with the evacuation port, and an NO port of the second two-position three-way valve 442 is connected with the mass flowmeter 120.

The liquid sample to be measured or the liquid for treating the sample to be measured may be injected into the purge mechanism through the injection mechanism. The injection mechanism includes a syringe pump 210 with a six-position valve 211, an ultrapure water bottle 220, a methanol bottle 240, and a watery bottle 250 (storing a liquid sample to be tested). The six-position valve 211 has six ports, wherein the five ports are respectively connected with the ultrapure water bottle 220, the purge tube 310, the waste liquid bottle 710, the methanol bottle 240 and the water sample bottle 250, and a third two-position three-way valve 261 is arranged between the ultrapure water bottle 220 and the six-position valve 211. The COM port of the third two-position three-way valve 261 is connected with the six-position valve 211, the NO port is connected with the ultra-pure water bottle 220, the NC port is connected with one end of the water storage tank 230, and the other end of the water storage tank 230 is connected with the ultra-pure water bottle 220. Under the action of the syringe pump 210, the liquid in the ultrapure water bottle 220 (or the water storage tank 230), the methanol bottle 240 and the water bottle 250 is injected into the purge pipe 310. It should be noted that the six-position valve 211 on the syringe pump 210 may be configured as a multi-position valve with other port numbers, and is specifically determined according to the liquid amount of the liquid sample to be tested, the pretreatment solvent, and the like, which need to be accessed or output.

Some of the components purged from the sample to be tested may contain high concentrations of components or other components that may contaminate the analytical column 610 and may be filtered by a filtering mechanism before entering the analytical column 610. The filtering mechanism comprises a pre-column 510, wherein the pre-column 510 is a capillary column with the working temperature of 180-220 ℃, a first end of the pre-column 510 is communicated with the transmission line 420, a second end of the pre-column is communicated with the analysis column 610, and the filtering mechanism is used for filtering out part of components in the components to be tested before the components to be tested enter the analysis column 610, so that the analysis column 610 is prevented from being polluted by high-concentration components or other components, and the service life of the analysis column 610 is reduced. The pre-column 510 is preferably a 624 capillary column of 2m x 0.25mm x 1.4um, which can be placed in a constant temperature column box to ensure the working temperature, and after the analysis is finished, the pre-column 510 can be aged by increasing the temperature of the constant temperature column box in which the pre-column 510 is positioned.

The filtering mechanism may also include a second two-position six-way valve 521. The pre-column 510 is connected to the transfer line 420 and the analytical column 610 through a second two-position six-way valve 521, and the second two-position six-way valve 521 is used for switching the pre-column 510 to determine whether the desorbed component to be tested passes through the pre-column 510. Specifically, the second two-position six-way valve 521 includes six ports in a clockwise annular array, which are a first port, a second port, a third port, a fourth port, a fifth port, and a sixth port, respectively. Wherein the third interface connects to the second end of the pre-column 510, the fourth interface connects to the analytical column 610, the fifth interface connects to the transmission line 420, and the sixth interface connects to the first end of the pre-column 510. When the second two-position six-way valve 521 is in the filtering position (the first port is communicated with the second port, the third port is communicated with the fourth port, and the fifth port is communicated with the sixth port, as shown in fig. 2), the first end of the pre-column 510 is communicated with the transmission line 420, the second end is communicated with the analysis column 610, and the desorbed component to be tested enters the analysis column 610 through the pre-column 510. When the second two-position six-way valve 521 is in the exhaust position (the second port is communicated with the third port, the fourth port is communicated with the fifth port, and the sixth port is communicated with the first port, as in fig. 1), the transmission line 420 is directly communicated with the analytical column 610, and the desorbed component to be tested directly enters the analytical column 610 by skipping the pre-column 510.

In addition, the first port of the second two-position six-way valve 521 may be used for evacuation, the second port may be used for introducing gas, and when the second two-position six-way valve 521 is in the evacuation position, the gas introduced by the second port flows through the third port, the pre-column 510, the sixth port and the first port in sequence, so as to realize evacuation of the pre-column 510. The second two-position six-way valve 521 is preferably capable of withstanding a pneumatic rotary valve at 250 c. The gas introduced into the second port of the second two-position six-way valve 521 may be the first gas, i.e., the second port of the second two-position six-way valve 521 may be in communication with the gas source 110 through a gas barrier. The air resistance is preferably a stainless steel air resistance pipe with the length of 1-1.5 m, the outer diameter of 1/16 inch and the inner diameter of 0.005 inch.

The gas source 110 is preferably a helium source 110, and the outlet pressure of the pressure reducing valve is preferably 0.4-0.5 MPa. The analysis mechanism may be a gas chromatograph or a gas chromatograph-mass spectrometer and the second gas inlet 430 may be provided by a chromatographic sample inlet. The chromatographic sample inlet is connected with the trapping mechanism through a capillary hollow pipe, one end of the capillary hollow pipe is communicated with the bottom of the chromatographic sample inlet, and the other end of the capillary hollow pipe is communicated with the second end of the trapping pipe 410 through a second interface of the first two-position six-way valve 441. The capillary hollow tube preferably has an inner diameter of 0.53mm and a length of 0.5 to 1m. Analytical column 610 is preferably a 30m 0.25mm 1.4um 624 capillary column placed in a temperature programmable column box.

It is apparent that the above examples of the present solution are merely examples for clearly illustrating the present solution and are not limiting of the embodiments of the present solution. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present solution should be included in the protection scope of the present solution claims.

Claims (10)

1. A purge-and-trap device for use with an analytical mechanism having an analytical column, comprising a purge mechanism for containing a sample to be tested and purging components to be tested in the sample to the trap mechanism by means of a first gas, and a trap mechanism for desorbing the components to be tested after adsorption and delivering the components to be tested to the analytical column by means of a second gas; the device is characterized in that the trapping mechanism comprises a trapping pipe, the trapping pipe is an inertized hollow pipe with the trapping temperature of-180 ℃ to-130 ℃ and the inner diameter of 1-2 mm, a first end of the trapping pipe is communicated with the purging mechanism in an adsorption stage, is communicated with the analysis column through a transmission line in a desorption stage, and a second end of the trapping pipe is communicated with a second gas inlet; the transmission line is a capillary tube with the inner diameter of 0.20-0.35 mm, and the second gas is used for conveying all components to be tested to the analysis column.

2. The purge and trap device according to claim 1, wherein the trap tube is an inerted stainless steel hollow tube; and/or the length of the collecting pipe is 10-15 cm; and/or the transmission line is a stainless steel passivation capillary; and/or the length of the transmission line is 0.5-1 m.

3. The purge and trap device according to claim 1, wherein the trap mechanism further comprises a first two-position six-way valve, the trap tube communicating with the purge mechanism, the transmission line and the second gas inlet through the first two-position six-way valve.

4. A purge and trap device according to any one of claims 1 to 3, further comprising a filtering mechanism comprising a pre-column for filtering out a portion of the components to be tested before they enter the analytical column; the pre-column is a capillary column with the working temperature of 180-220 ℃, the first end of the pre-column is communicated with the transmission line, and the second end of the pre-column is communicated with the analysis column.

5. The purge and trap device according to claim 4, wherein the filtering mechanism further comprises a second two-position six-way valve, the pre-column communicating the transmission line with the analytical column through the second two-position six-way valve.

6. The purge and trap device according to claim 4, wherein the pre-column is placed in a constant temperature column box to maintain an operating temperature.

7. The purge and trap device according to claim 6, wherein the thermostatic cartridge ages the pre-cartridge after completion of the operation.

8. The purge and trap device according to claim 4, further comprising a source of the first gas, the source of the first gas being in communication with the inlet of the purge mechanism during the adsorption phase, with the first end of the trap and/or with the second end of the pre-column during the evacuation phase, the second end of the trap and/or the first end of the pre-column being in communication with the outside during the evacuation phase.

9. A purge and trap device according to any one of claims 1 to 3, wherein the analysis means is a gas chromatograph or a gas chromatograph-mass spectrometer, and the second gas inlet is provided by a chromatographic sample inlet.

10. The purge and trap device according to claim 9, wherein the chromatographic sample inlet is connected to the trap mechanism by a capillary tube, one end of the capillary tube is connected to the bottom of the chromatographic sample inlet, and the other end is connected to the first end of the trap tube.