Device and method for removing moisture and collecting target residue in organic matter monitoring

Abstract

The invention discloses a device and method for removing moisture and collecting target object residues in organic matter monitoring, and belongs to the technical field of environmental monitoring, the device comprises a headspace bottle, a condensation module and a passage module, the condensation module comprises a base and a semiconductor temperature adjusting piece, a placement cavity is formed in the middle of the base, and the semiconductor temperature adjusting piece is arranged in the placement cavity; the semiconductor temperature adjusting sheet is positioned on the outer side of the base; the passage module comprises a top cover, a pure water tank and a methanol bottle; a waste gas inlet pipeline, a waste gas outlet pipeline and a water injection pipe which are communicated with the mounting cavity are arranged at the upper end of the top cover. The headspace bottle is refrigerated, vaporous water is condensed into liquid water to be left in the bottle, meanwhile, pure water or a methanol solution is injected to enable organic matter residues in the headspace bottle to be dissolved into the pure water (or a methanol aqueous solution), and loss of VOCs is avoided. The device is simple in structure and convenient to operate, and errors of the sampling volume are eliminated; and meanwhile, the accuracy of detection data is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental monitoring, and particularly relates to a device and method for moisture removal and target residue collection in organic matter monitoring. Background Art

[0002] The monitoring of organic matter in the exhaust gas from stationary pollution sources is of great significance for protecting public health, controlling compound pollution, and fulfilling regulations, and also provides scientific basis and data support for environmental governance and sustainable economic development. Among them, the monitoring of volatile organic compounds (VOCs) is particularly crucial. Currently, there are more than a dozen monitoring method standards for VOCs. Among them, "Determination of Volatile Organic Compounds in Exhaust Gas from Stationary Pollution Sources - Solid Phase Adsorption-Thermal Desorption / Gas Chromatography-Mass Spectrometry" (HJ 734-2014) is applicable to as many as 24 substances and is the most widely used.

[0003] However, during the collection process of solid samples, the moisture content in the exhaust gas from many stationary pollution sources is very high, with a volume percentage as high as 30%. Such a high moisture content will greatly reduce the adsorption efficiency of the solid phase adsorption for the target substances and interfere with laboratory analysis. Therefore, in section 7.3.1 of HJ 734-2014 for the sampling of adsorption tubes, it is stipulated that if there is interference from water vapor, a small ice bath impact type moisture collector or a semiconductor refrigeration dehumidification device can be added in front of the adsorption sampling tube. The water in the moisture collector should be analyzed simultaneously by HJ 639 (purge and trap-gas chromatography / mass spectrometry), and the content should be included in the sample.

[0004] Whether it is an ice bath or semiconductor refrigeration dehumidification, their essence is refrigeration dehydration. During this dehydration process, when the exhaust gas sample enters the low-temperature area, not only gaseous water will condense, but also some high-concentration, high-boiling-point, and strong-polarity organic substances will condense or adsorb, resulting in sample loss and a lower monitoring result. Therefore, HJ 734-2014 requires analyzing the collected condensed water by purge and trap-gas chromatography / mass spectrometry (HJ 639) and adding the content of VOCs in it to the final result. However, in actual monitoring, this method has many problems: The actual volume of the condensed water is usually less than 0.5 mL. If it contains VOCs, the concentration is often very high. During the process of opening the lid and transferring, the condensed water and the inner wall of the dehydration device will surely come into contact with the atmosphere. For such a small volume of water in contact with the atmosphere, it is easy to cause the volatilization loss of VOCs in the condensed water and on the inner wall of the dehydration device; There are often residual organic substances on the inner wall of the dehydration device. Some substances are insoluble in water, and the original method only uses pure water for cleaning and transfer, which is also easy to cause sample loss; After the condensed water is transferred into the purge sample bottle, it generally needs to be filled with pure water to 40 mL, sealed after checking for no bubbles. This process is not carried out in a closed environment, which is easy to cause the volatilization loss of VOCs; The dead volume of the dehydration device is relatively large. When the minimum sampling volume of 300 mL specified in HJ 734 is adopted, the influence of the dead volume is significant. For the small impact moisture collector according to HJ 734, the minimum volume of each is 10 mL, and three in series is 30 mL. Then, for the 30 mL of gas at the initial stage of sample collection, it is all the gas originally present in the device. When collecting 300 mL, the actually collected sample gas is only 300 - 30 = 270 mL, which is 90% of the set sampling volume, and a large error will occur during result calculation. The process of dehydrating and collecting moisture by the existing method is complex and not suitable for on-site monitoring.

[0005] In summary, it is urgent to develop and innovate a new device and method for moisture removal and target residue collection. Summary of the Invention

[0006] The purpose of the present invention is to provide a device and method for moisture removal and target residue collection in organic matter monitoring to solve the problems existing in the background technology.

[0007] The purpose of the present invention is achieved through the following technical solutions: A device for moisture removal and target residue collection in organic matter monitoring includes a headspace bottle, a condensation module, and a passage module: A screw cap is provided at the top of the headspace bottle, a silicone gasket is provided in the middle of the screw cap, and a PTFE film is provided on the side of the silicone gasket facing the inside of the bottle. The condensation module includes a base and a semiconductor temperature regulator. A placement cavity is provided in the middle of the base, and the semiconductor temperature regulator is located outside the base. The passage module includes a top cover, a pure water tank, and a methanol bottle. The top cover is located above the base and is detachably connected to the base. An installation cavity is provided in the middle of the top cover. After the top cover and the base are combined, the headspace bottle is surrounded through the installation cavity and the placement cavity. An exhaust gas inlet pipeline, an exhaust gas outlet pipeline, and a water injection pipe communicating with the installation cavity are provided at the upper end of the top cover. One end of the exhaust gas inlet pipeline extends into the bottom of the headspace bottle, and the other end of the exhaust gas inlet pipeline is detachably connected to the outlet of the exhaust gas sampling pipe. One end of the exhaust gas outlet pipeline extends into the top of the headspace bottle, and the other end of the exhaust gas outlet pipeline is detachably connected to an exhaust gas absorption device. One end of the water injection pipeline extends into the bottom of the headspace bottle, and the other end of the water injection pipeline is connected to the pure water tank and the methanol bottle respectively through a three-way valve. A peristaltic pump is provided between the three-way valve and the water injection pipeline. The exhaust gas sampling pipe extends into the exhaust gas pipeline for sampling. A temperature adjustment device is provided outside the exhaust gas sampling pipe. The exhaust gas absorption device successively includes an adsorption tube, a filter, a flow controller, and an air pump.

[0008] Further, syringe needles are provided at the insertion ends of the waste gas inlet pipeline, the waste gas outlet pipeline, and the water injection pipe.

[0009] Further, a circle of through holes is provided outside the syringe needles of the waste gas inlet pipeline and the waste gas outlet pipeline, and the through holes are close to the needle tips of the syringe needles.

[0010] Further, both the base and the top cover are made of aluminum alloy material. An insulating layer is provided on the outer side of the top cover. The radii of the placement cavity and the installation cavity are 0.5 mm larger than the radius of the headspace bottle. A drain hole communicating with the placement cavity is provided at the bottom of the base.

[0011] Further, a radiator is provided on the side of the semiconductor temperature regulating sheet away from the base.

[0012] Further, the pure water tank and the methanol bottle are of a sealed structure. One-way valves are provided at the tops of the pure water tank and the methanol bottle. Activated carbon adsorption tubes and organic matter filter membranes are provided at the air inlets of the one-way valves.

[0013] Further, a guide rail is provided between the top cover and the base, and the top cover is detachably connected to the base through the guide rail.

[0014] A method for moisture removal and target residue collection in organic matter monitoring includes the following steps: S1: Fill the headspace bottle with high-purity nitrogen and seal it with a screw cap. S2: Place the headspace bottle in the placement cavity of the base. At this time, the passage module is located above the condensation module, and at the same time, the pipeline connectors of the passage module are all in a closed state. S3: Move the passage module downward to install it with the condensation module. The top cover abuts against the base. At this time, one ends of the waste gas inlet pipeline, the waste gas outlet pipeline, and the water injection pipe are inserted into the headspace bottle. The other end of the waste gas inlet pipeline is connected to the waste gas sampling pipe, and the other end of the waste gas outlet pipeline is connected to the waste gas absorption device. S4: Cool the base and the headspace bottle inside the base through the semiconductor temperature regulating sheet so that the temperature inside the headspace bottle is between 0 and 4 °C. S5: Perform sampling through the air pump and the flow controller. The waste gas sample enters the headspace bottle, and the gaseous water in the waste gas sample will condense and remain in the headspace bottle due to the low temperature. S6: After sampling, close the inlet end of the waste gas inlet pipeline, disconnect the waste gas inlet pipeline from the waste gas sampling pipe, stop cooling by the semiconductor temperature regulating sheet, connect the water injection pipe and the pure water tank through the three-way valve, and pump pure water into the headspace bottle through the peristaltic pump. At this time, the waste gas sample in the headspace bottle is squeezed into the waste outlet pipeline by the pure water and flows into the adsorption tube. S7: Fill the headspace vial with pure water. When there are water droplets at the outlet end of the exhaust gas outlet pipe, stop pumping in pure water, close the switch at the outlet end of the exhaust gas outlet pipe, and disconnect the exhaust gas outlet pipe from the adsorption tube.

[0015] S8: Lift the passage module, remove the exhaust gas inlet pipe, exhaust gas outlet pipe, and water injection pipe from the headspace vial. After removing the headspace vial, invert it and check whether there are bubbles in the headspace vial and whether the silicone gasket leaks. If bubbles are found, quickly open the screw cap, drip in pure water, and seal it quickly. If it is found that the silicone hole is too large and leaks, quickly open the screw cap and replace the silicone gasket. S9: Analyze the water sample in the headspace vial. Take 5 mL from the water sample in the sealed headspace vial and analyze the VOCs in the water sample by a purge and trap instrument connected to a gas chromatograph. Take 2 mL from the remaining water sample and analyze the polar organic compounds in it by a liquid chromatography - mass spectrometer. Then, liquid - liquid extract the remaining water sample with an organic solvent, concentrate the extract to 1 mL, and analyze the non - polar organic compounds in it by a gas chromatography - mass spectrometer.

[0016] Further, in step S6, if there are organic compounds with very low solubility in water in the exhaust gas sample of the headspace vial, connect the water injection pipe and the methanol bottle through a three - way valve, and pump methanol into the headspace vial through a peristaltic pump.

[0017] The beneficial effects of the present invention are as follows: Prevent the volatilization loss of VOCs and collect residual organic compounds: This device avoids the direct contact between the condensed water, the inner wall of the dehydrator, and the atmosphere, fundamentally eliminating the loss of VOCs dissolved in water due to volatilization, and simultaneously collecting the VOCs dissolved in water and the semi - volatile organic compounds (SVOCs) with relatively low volatility remaining on the inner wall.

[0018] Reduce residual loss: By filling the headspace vial with pure water or an aqueous methanol solution, the organic compound residues in the headspace vial are dissolved in it, avoiding the loss of organic compounds such as VOCs during transfer and other processes.

[0019] Optimized device structure: This device has a simple structure and is easy to operate, minimizing the dead volume as much as possible, greatly reducing the error caused by the sampling volume, and further ensuring the accuracy of the monitoring data.

[0020] Accurately determine the content of VOCs: Determine the VOCs dissolved in water and the VOCs in the adsorption tube separately, and the sum of the two detection results is the actual value, greatly improving the accuracy of the data. Specifically, analyze the VOCs in the water sample by a purge and trap instrument connected to a gas chromatograph; analyze the organic compounds with a certain polarity and relatively high boiling point in the water sample by means of a liquid chromatography - mass spectrometer; analyze the non - polar and relatively high - boiling organic compounds in the water sample by a gas chromatography - mass spectrometer.

[0021] Can be used for the monitoring of SVOCs: In addition to analyzing VOCs, SVOCs can also be determined. Such substances have relatively high boiling points and weak volatility. When high-temperature waste gas enters the dehydrator, due to the sharp drop in temperature, they will adsorb or condense on the inner wall of the dehydrator. This device can dissolve them in water or an aqueous methanol solution, and then determine their content. Brief Description of the Drawings

[0022] Figure 1 It is a schematic diagram of a device for removing moisture and collecting target residue in the monitoring of organic substances according to the present invention; Figure 2 It is a schematic diagram of the headspace bottle in the present invention; Figure 3 It is a top view of the condensation module in the present invention; Figure 4 It is a schematic diagram of the condensation module and the passage module in the present invention; Figure 5 It is a schematic diagram of the syringe in the present invention; Figure 6 It is a schematic diagram of step S2 in Embodiment 2 of the present invention; Figure 7 It is a schematic diagram of step S3 in Embodiment 2 of the present invention; Figure 8 It is a schematic diagram of step S4 in Embodiment 2 of the present invention; Figure 9 It is a schematic diagram of step S5 in Embodiment 2 of the present invention; Figure 10 It is a schematic diagram of adding pure water in step S6 in Embodiment 2 of the present invention; Figure 11 It is a schematic diagram of adding methanol in step S6 in Embodiment 2 of the present invention; Figure 12 It is a schematic diagram of step S7 in Embodiment 2 of the present invention; Figure 13 It is a schematic diagram of step S8 in Embodiment 2 of the present invention; In the figure, 1 - headspace bottle, 101 - screw cap, 2 - condensation module, 21 - base, 22 - semiconductor temperature regulator, 23 - radiator, 24 - placement cavity, 25 - drain hole, 3 - passage module, 31 - waste gas inlet pipeline, 32 - waste gas outlet pipeline, 33 - water injection pipe, 34 - peristaltic pump, 35 - three-way valve, 36 - installation cavity, 37 - syringe, 38 - through hole, 39 - top cover, 6 - pure water tank, 7 - methanol bottle, 8 - one-way valve, 9 - waste gas sampling pipe, 10 - waste gas absorption device, 11 - adsorption tube, 12 - flow controller, 13 - air pump. Detailed Description of the Invention

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0024] Embodiment 1: Refer to Figures 1 - 5 , the present invention provides a technical solution: A device for removing moisture and collecting target residue in organic matter monitoring, including a headspace bottle 1, a condensation module 2 and a passage module 3: The headspace bottle 1 is provided with a screw cap 101 at the top. The middle of the screw cap 101 is hollow and is provided with a silica gel gasket. A PTFE film is provided on the side of the silica gel gasket facing the inside of the bottle.

[0025] Through the structure of the headspace bottle 1, the headspace bottle 1 is pre-filled with high-purity nitrogen and sealed with the screw cap 101. The middle of the screw cap 101 is a hollow structure. The inner side of the screw cap 101 is provided with a silica gel gasket, and the silica gel gasket is installed in the screw cap 101 and will not come out. The hollow part of the screw cap 101 is blocked and sealed by the silica gel gasket. And a PTFE film is provided on the side of the silica gel gasket close to the inside of the headspace bottle 1. By setting the PTFE film, it can be avoided that the side of the silica gel gasket close to the inside of the bottle adsorbs organic matter and causes residue.

[0026] The condensation module 2 includes a base 21 and a semiconductor temperature control chip 22. A placement cavity 24 is provided in the middle of the base 21, and the semiconductor temperature control chip 22 is located outside the base 21.

[0027] The sealed headspace bottle 1 is inserted into the placement cavity 24 of the base 21. The radius of the placement cavity 24 is 0.5 mm larger than the radius of the headspace bottle 1, so that the headspace bottle 1 is convenient to take and place, and at the same time, the refrigeration effect is not affected. The depth of the placement cavity 24 is less than the height of the headspace bottle 1, and the screw cap 101 part of the headspace bottle 1 is exposed outside the placement cavity 24 for convenient operation.

[0028] A semiconductor temperature control chip 22 is provided on one side of the outside of the base 21. The base 21 is made of aluminum alloy with a high thermal conductivity coefficient, so that the headspace bottle 1 in the placement cavity 24 can be quickly cooled by the semiconductor temperature control chip 22. At the same time, a radiator 23 is provided on the side of the semiconductor temperature control chip 22 away from the base 21. At the same time, an insulating layer is provided at the position of the base 21 where the semiconductor temperature control chip 22 is not provided outside to keep the temperature in the placement cavity 24 stable.

[0029] Furthermore, a drain hole 25 communicating with the placement cavity 24 is provided at the bottom of the base 21. When the headspace bottle 1 is cooled, if there is liquefied frost water inside the placement cavity 24 and outside the headspace bottle 1, it will flow out from the drain hole 25.

[0030] The passage module 3 includes a top cover 39, a pure water tank 6 and a methanol bottle 7. The top cover 39 is located above the base 21 and is detachably connected to the base 21. An installation cavity 36 is provided in the middle of the top cover 39. After the top cover 39 and the base 21 are fitted together, the headspace bottle 1 is surrounded by the installation cavity 36 and the placement cavity 24.

[0031] After the headspace bottle 1 is placed in the placement cavity 24, at this time, the pure water tank 6 and the methanol bottle 7 do not move. The pure water tank 6 and the methanol bottle 7 are of a sealed structure. One-way valves 8 are provided at the tops of the pure water tank 6 and the methanol bottle 7, and the gas can only flow into the tank (bottle) from the outside through the one-way valves 8. At the same time, an activated carbon adsorption tube 11 and an organic matter filter membrane are provided at the air inlet of the one-way valve 8 to prevent particulate matter and organic matter in the external air from entering the tank (bottle).

[0032] Move the top cover 39 towards the base 21. Since the pipeline connected to the top cover 39 above is relatively long, it is convenient for the top cover 39 to move onto the base 21. The headspace bottle 1 can be completely covered through the installation cavity 36 and the placement cavity 24. The top cover 39 is also made of aluminum alloy material, and a heat insulation layer is provided on the outer surface to conduct heat and keep warm the upper part of the headspace bottle 1.

[0033] Furthermore, a guide rail is provided between the top cover 39 and the base 21, and the top cover 39 can approach and move away from the base 21 along the guide rail, which is convenient for alignment and easy to operate.

[0034] An exhaust gas inlet pipeline 31, an exhaust gas outlet pipeline 32 and a water injection pipe 33 communicating with the installation cavity 36 are provided at the upper end of the top cover 39. One end of the exhaust gas inlet pipeline 31 extends into the bottom of the headspace bottle 1, and the other end of the exhaust gas inlet pipeline 31 is detachably connected to the outlet of the exhaust gas sampling pipe 9. One end of the exhaust gas outlet pipeline 32 extends into the top of the headspace bottle 1, and the other end of the exhaust gas outlet pipeline 32 is detachably connected to the exhaust gas absorption device 10.

[0035] The exhaust gas inlet pipeline 31, the exhaust gas outlet pipeline 32 and the water injection pipe 33 respectively pass through the top cover 39. The exhaust gas inlet pipeline 31 and the exhaust gas outlet pipeline 32 are in an L shape. Switch joints are provided on one side of the exhaust gas inlet pipeline 31 and the exhaust gas outlet pipeline 32 outside the top cover 39, and the corresponding flow paths can be closed through the switch joints.

[0036] One end of the water injection pipe 33 extends into the bottom of the headspace bottle 1, and the other end of the water injection pipe 33 is connected to the pure water tank 6 and the methanol bottle 7 respectively through pipelines and a three-way valve 35. A peristaltic pump 34 is provided between the three-way valve 35 and the water injection pipe 33.

[0037] At the same time, the exhaust gas inlet pipeline 31, the exhaust gas outlet pipeline 32, the water injection pipe 33 and the corresponding switch joints and three-way valve 35 are all made of inert materials.

[0038] Further, syringe needles 37 are provided at the insertion ends of the waste gas inlet pipeline 31, the waste gas outlet pipeline 32, and the water injection pipe 33.

[0039] When the passage module 3 cooperates with the condensation module 2, by arranging the syringe needles 37 at the ends, it is convenient for the waste gas inlet pipeline 31, the waste gas outlet pipeline 32, and the water injection pipe 33 to pierce the silica gel gasket on the screw cap 101, and then insert the waste gas inlet pipeline 31, the waste gas outlet pipeline 32, and the water injection pipe 33 into the headspace bottle 1. At the same time, the silica gel gasket has a certain elasticity. After the syringe needle 37 pierces the silica gel gasket, the silica gel gasket will contract the notch and then tighten around the pipeline to achieve a sealing effect.

[0040] Further, a circle of through holes 38 is provided at the needle ends of the syringe needles 37 of the waste gas inlet pipeline 31 and the waste gas outlet pipeline 32, and the through holes 38 are close to the needle tips of the syringe needles 37. The through holes 38 are designed in this way so that they are not easily blocked by silica gel debris; and, after the waste gas enters the headspace bottle 1 through the through holes 38, it can flow out in multiple directions at a low flow rate (flow rate per hole ≤ 5 mL / min), and can complete heat exchange more efficiently, which is beneficial to the condensation of water.

[0041] The waste gas sampling tube 9 extends into the waste gas pipeline for sampling. A temperature adjustment device is provided outside the waste gas sampling tube 9. The waste gas absorption device 10 successively includes an adsorption tube 11, a filter, a flow controller 12, and an air pump 13.

[0042] After the top cover 39 and the base 21 are closed, the waste gas sampling tube 9 is connected to the waste gas inlet pipeline 31, and one end of the adsorption tube 11 is connected to the waste gas outlet pipeline 32. At this time, when the air pump 13 is started, the waste gas can be drawn from the waste gas sampling tube 9 into the headspace bottle 1, and at the same time, the waste gas also flows along the flow path into the adsorption tube 11 for adsorption. The flow rate can be adjusted through the flow controller 12, and a filter is provided at the front end of the flow controller 12 to prevent the waste gas from damaging the flow controller 12.

[0043] During the sampling process, the waste gas is refrigerated by the condensation module 2, and the gaseous water in the headspace bottle 1 will condense into liquid and remain in the headspace bottle 1.

[0044] After the sampling is completed, pure water is slowly added to the headspace bottle 1 through the peristaltic pump 34. The gas in the headspace bottle 1 will be squeezed into the waste gas outlet pipeline 32 and then flow into the adsorption tube 11. The VOCs in the waste gas are adsorbed by the adsorption tube 11, thereby eliminating the error of the sampling volume. At the same time, a small amount (less than 5 mL) of methanol can be selectively added to promote the dissolution of organic substances.

[0045] After the headspace bottle 1 is filled with pure water, the organic substances in the condensed water will dissolve, and the organic substances adsorbed on the inner wall will also gradually dissolve in the water sample. The headspace bottle 1 is removed for subsequent analysis of the water sample.

[0046] With the device of the present application, the collection and condensation of samples can be quickly completed, reducing the loss of VOCs due to dispersion, eliminating the error in sampling volume. At the same time, it can not only analyze the VOCs in the waste gas, but also determine semi-volatile organic compounds (SVOCs). Such substances have weak volatility. When high-temperature waste gas enters the dehydrator, due to the sharp drop in temperature, they will adsorb or condense on the inner wall of the dehydrator. This device can dissolve them in water or an aqueous methanol solution, and then determine their content. In the original HJ734, only the condensed water during the sampling process was collected, and the purge and trap method was used to analyze the volatile organic compounds in it, without analyzing semi-volatile organic compounds, that is, SVOCs could not be analyzed.

[0047] Example 2: Refer to Figures 1 - 13 , the present invention provides a technical solution: A method for removing moisture and collecting target residue in organic matter monitoring, comprising the following steps: S1: The headspace vial 1 is filled with high-purity nitrogen and sealed with a screw cap 101. The capacity of the headspace vial 1 is 40 mL.

[0048] S2: As Figure 6 shown, the headspace vial 1 is placed in the placement cavity 24 of the base 21. At this time, the passage module 3 is located above the condensation module 2, and at the same time, the pipeline joints of the passage module 3 are all in a closed state.

[0049] S3: As Figure 7 shown, the passage module 3 is moved downward to be installed with the condensation module 2, and the top cover 39 abuts against the base 21. At this time, one ends of the waste gas inlet pipeline 31, the waste gas outlet pipeline 32 and the water injection pipe 33 enter the headspace vial 1 through a syringe needle 37 to pierce the silicone gasket and the PTFE film. Then, the other end of the waste gas inlet pipeline 31 is connected to the waste gas sampling pipe 9, and the waste gas sampling pipe 9 extends into the waste gas pipeline for sampling. The other end of the waste gas outlet pipeline 32 is connected to one end of the adsorption pipe 11 of the waste gas absorption device 10. The waste gas sampling pipe 9 is kept at a constant temperature of 120 °C through an external stable adjustment device, which helps to avoid the residue of the target substance on the inner wall of the waste gas sampling pipe 9 during the sampling process. At the same time, the adsorption pipe 11 is filled with a solid-phase adsorbent (such as graphitized carbon black, carbon molecular sieve, etc.).

[0050] S4: As Figure 8As shown, the semiconductor temperature regulator 22 cools the base 21 and the headspace vial 1 inside the base 21, so that the temperature inside the headspace vial 1 is between 0 and 4 °C. At the same time, a temperature sensor can be set in the placement chamber 24 to measure the temperature of the headspace vial 1 in real time, record the temperature difference from the outside, and dynamically adjust the temperature through the semiconductor temperature regulator 22. If a stronger water removal effect is pursued, it can also be condensed into ice. Without overly pursuing the refrigeration effect, using a refrigeration sheet with common power and size, the lowest temperature of the condensation module 2 in this design can reach -20 °C.

[0051] For samples with good water solubility, high boiling point, and high concentration, when the water content exceeds 3%, obvious losses of the above-mentioned types of organic substances will occur in the conventional water removal device. However, in this application, after the waste gas sample enters the headspace vial 1, the gaseous water in the waste gas sample can be condensed and left in the headspace vial 1 through the condensation module 2.

[0052] S5: As Figure 9 shown, when the temperature of the condensation module 2 reaches the set value, open the switch joints of the waste gas inlet pipeline 31 and the waste gas outlet pipeline 32, open the flow path, and perform sampling through the air pump 13 and the flow controller 12. The flow rate is controlled at 20 - 50 mL / min. At this flow rate, after the waste gas enters the headspace vial 1, due to the low temperature, the gaseous water will be condensed into a liquid and left in the headspace vial 1. At the same time, the moisture content of the waste gas at the end of the waste gas outlet pipeline 32 of the headspace vial 1 is generally lower than 0.8% (v / v) at 0 - 4 °C. The gas flowing into the adsorption tube 11 is relatively dry, and the VOCs inside are adsorbed by the adsorption packing in the adsorption tube 11. The adsorption packing can adopt the relevant packing of HJ 734. Currently, the method of HJ 734 is used to analyze the volatile organic compounds in the waste gas from stationary pollution sources. Generally, compounds around C3 - C10 in the waste gas can be trapped, including alkanes, alkenes, benzene series, oxygen-containing organic compounds, etc. In fact, more than 100 compounds can be trapped and desorbed.

[0053] At the same time, high-boiling-point, high-concentration organic substances and high-concentration, water-soluble organic substances such as alcohols, methanol, ethanol, propanol, etc. will partially accumulate in the headspace vial 1.

[0054] At the same time, the sampling volume of this application can be in the range of 300 mL - 2000 mL, and waste gas with a temperature of up to 200 °C can be collected, or waste gas with a water content of 1% - 30% can be collected. The sampling range of this application is wide and the applicability is good.

[0055] S6: As Figure 10As shown, after sampling, close the inlet end of the exhaust gas inlet pipeline 31, disconnect the exhaust gas inlet pipeline 31 from the exhaust gas sampling tube 9, stop the semiconductor temperature control chip 22 from refrigerating, connect the water injection pipe 33 and the pure water tank 6 through the three-way valve 35, and pump pure water into the headspace bottle 1 through the peristaltic pump 34 at a flow rate of 20 mL / min. The organic substances adsorbed or condensed in the headspace bottle 1 will dissolve in the pure water. If the air pressure in the pure water bottle is too small, air will be drawn in from the outside through the one-way valve 8 to balance the air pressure. The flow controller 12 and the air pump 13 are still turned on to control the air flow rate to be equal to the pure water addition rate. At the same time, as pure water is added, the exhaust gas sample in the headspace bottle 1 is squeezed into the waste outlet pipeline by the pure water and flows into the adsorption tube 11, so that VOCs are adsorbed therein.

[0056] As Figure 11 As shown, in step S6, if there are organic substances with poor water solubility and high concentration in the exhaust gas sample of the headspace bottle 1, connect the water injection pipe 33 and the methanol bottle 7 through the three-way valve 35, and pump methanol into the headspace bottle 1 through the peristaltic pump 34. Methanol aqueous solution is formed by adding methanol to improve the dissolution ability of organic substances. The rate of adding methanol is controlled at 5 mL / min, and the added amount is between 2 - 10 mL. After adding the set amount of methanol, switch the three-way valve 35 and continue to add pure water.

[0057] If the exhaust gas mainly contains organic substances with poor water solubility, high boiling point and high concentration, such as high molecular weight benzene series, hydrocarbons, chlorobenzenes, polycyclic aromatic hydrocarbons, PFASs, etc., if the concentration of these types of substances is too high, they are not evenly dissolved in the aqueous solution, so methanol needs to be added to promote dissolution. When the target substances of concern are not VOCs, methanol can also be added entirely without adding pure water. In this case, after the headspace bottle 1 is transported to the laboratory, it is not suitable to use the purge and trap method for analysis. It is advisable to directly concentrate and inject for analysis or concentrate and inject for analysis after solvent replacement.

[0058] S7: As Figure 12 As shown, fill the headspace bottle 1 with pure water. When there are water droplets at the outlet end of the exhaust gas outlet pipeline 32, stop pumping pure water, close the switch at the outlet end of the exhaust gas outlet pipeline 32, and disconnect the exhaust gas outlet pipeline 32 from the adsorption tube 11. Since the headspace bottle 1 has a volume of 40 mL, when the injected pure water is close to 40 mL, close the switch joint at one end of the exhaust gas outlet pipeline 32 and remove the adsorption tube 11, etc. If it is found that the headspace bottle 1 may not be fully filled with pure water, the switch joint of the exhaust gas outlet pipeline 32 can be reopened, and pure water can be injected through the peristaltic pump 34 at a flow rate of 5 mL / min. When water droplets are observed at the switch joint of the exhaust gas outlet pipeline 32, stop pumping pure water and close this switch joint. At the same time, it is necessary to ensure that there are no bubbles in the headspace bottle 1. At this time, the organic matter residues in the headspace bottle 1 are dissolved in the pure water (or methanol aqueous solution).

[0059] S8: As Figure 13As shown, lift the passage module 3, take out the waste gas inlet pipe 31, the waste gas outlet pipe 32 and the water injection pipe 33 from the headspace bottle 1. After taking out the headspace bottle 1, invert it and check whether there are bubbles in the headspace bottle 1 and whether the silica gel gasket leaks water. If bubbles are found, quickly open the screw cap 101, drip pure water, and quickly seal it. If it is found that the silica gel hole is too large and leaks water, quickly open the screw cap 101 and replace the silica gel gasket. When the syringe 37 of the passage module 3 is removed from the headspace bottle 1, the silica gel gasket of the headspace bottle 1 will squeeze the silica gel gasket to close the needle hole due to the water pressure and its own elasticity, avoiding air leakage. At the same time, sealing tape can be wound around the outside of the bottle cap to assist in sealing.

[0060] S9: Analyze the water sample in the headspace bottle 1. After the headspace bottle is sealed, it is transferred as a whole and placed on the detection instrument. Take 5 mL from the water sample in the sealed headspace bottle and analyze the VOCs in the water sample by connecting a purge and trap instrument to a gas chromatograph or by connecting it to a gas chromatography - mass spectrometer. Take 2 mL from the remaining water sample and analyze the polar organic compounds in it with a liquid chromatography - mass spectrometer. This part of the organic compounds mainly includes perfluorinated compounds (PFASs), antibiotics, long - chain fatty acids and their esters (such as stearic acid (octadecanoic acid) with a boiling point of 361 °C and palmitic acid (hexadecanoic acid) with a boiling point of 351.5 °C). At the same time, the boiling points of this part of the substances are relatively high, generally above 230 °C. Then, extract the remaining water sample by liquid - liquid extraction with an organic solvent, concentrate the extract to 1 mL, and analyze the non - polar organic compounds in it with a gas chromatography - mass spectrometer. This part of the organic compounds mainly includes polycyclic aromatic hydrocarbons, long - chain alkanes and alkenes, large - molecular - weight aromatic hydrocarbons and their derivatives, PCBs, etc.

[0061] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And the changes and modifications made by those skilled in the art that do not depart from the spirit and scope of the present invention should fall within the protection scope of the appended claims of the present invention.

Claims

1. A device for removing moisture and collecting target residues in organic matter monitoring, characterized in that: It includes a headspace bottle (1), a condensation module (2) and a passage module (3): The top of the headspace bottle (1) is provided with a screw cap (101), the middle of the screw cap (101) is provided with a silicone gasket, and the side of the silicone gasket facing the inside of the bottle is provided with a PTFE film; The condensation module (2) comprises a base (21) and a semiconductor temperature regulating plate (22); a placement cavity (24) is provided in the middle of the base (21); and the semiconductor temperature regulating plate (22) is located outside the base (21); The passage module (3) comprises a top cover (39), a pure water tank (6) and a methanol bottle (7); the top cover (39) is located above the base (21) and is detachably connected to the base (21); a mounting cavity (36) is provided in the middle of the top cover (39); and when the top cover (39) and the base (21) are matched, the top space bottle (1) is surrounded by the mounting cavity (36) and the placement cavity (24); The upper end of the top cover (39) is provided with an exhaust gas inlet pipeline (31), an exhaust gas outlet pipeline (32) and a water injection pipe (33) which are in communication with the installation cavity (36); one end of the exhaust gas inlet pipeline (31) extends into the bottom of the headspace bottle (1); the other end of the exhaust gas inlet pipeline (31) is detachably connected to the outlet of the exhaust gas sampling tube (9); one end of the exhaust gas outlet pipeline (32) extends into the top of the headspace bottle (1); the other end of the exhaust gas outlet pipeline (32) is detachably connected to the exhaust gas absorption device (10); one end of the water injection pipe (33) extends into the bottom of the headspace bottle (1); the other end of the water injection pipe (33) is respectively connected to the pure water tank (6) and the methanol bottle (7) through a three-way valve (35); a peristaltic pump (34) is provided between the three-way valve (35) and the water injection pipe (33); The waste gas sampling tube (9) extends into the waste gas pipeline for sampling, a temperature regulating device is provided outside the waste gas sampling tube (9), and the waste gas absorption device (10) comprises an adsorption tube (11), a filter, a flow controller (12) and an air pump (13) in sequence.

2. The device for removing water and collecting target residues in organic matter monitoring according to claim 1, characterized in that: Insertion ends of the exhaust gas inlet pipeline (31), the exhaust gas outlet pipeline (32) and the water injection pipe (33) are provided with needle tubes (37).

3. The device for removing water and collecting target residues in organic matter monitoring according to claim 2, characterized in that: A circle of through holes (38) is provided outside the needle tubes (37) of the exhaust gas inlet pipeline (31) and the exhaust gas outlet pipeline (32), and the through holes (38) are close to the needle heads of the needle tubes (37).

4. The device for removing water and collecting target residues in organic matter monitoring according to claim 1, characterized in that: The base (21) and the top cover (39) are both made of aluminum alloy material; a heat insulating layer is provided on the outer side of the top cover (39); the radius of the placement cavity (24) and the installation cavity (36) is 0.5 mm larger than the radius of the top space bottle (1); and a leakage hole (25) communicating with the placement cavity (24) is provided at the bottom of the base (21).

5. The device for removing water and collecting target residues in organic matter monitoring according to claim 1, characterized in that: A heat sink (23) is provided on a side of the semiconductor temperature regulating plate (22) away from the base (21).

6. The device for removing water and collecting target residues in organic matter monitoring according to claim 1, characterized in that: The pure water tank (6) and the methanol bottle (7) are sealed structures. A one-way valve (8) is provided on the top of each of the pure water tank (6) and the methanol bottle (7). An activated carbon adsorption tube (11) and an organic matter filter membrane are provided at the air inlet of the one-way valve (8).

7. The device for removing water and collecting target residues in organic matter monitoring according to claim 1, characterized in that: A guide rail is provided between the top cover (39) and the base (21), and the top cover (39) is detachably connected to the base (21) via the guide rail.

8. A method for removing moisture and collecting target residues in organic matter monitoring, comprising the device for removing moisture and collecting target residues in organic matter monitoring according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: The headspace bottle (1) is filled with high-purity nitrogen and sealed with a screw cap (101); S2: placing the headspace bottle (1) into the placement cavity (24) of the base (21), wherein the passage module (3) is located above the condensation module (2), and the pipe joints of the passage module (3) are all in a closed state; S3: The passage module (3) is moved downward and installed with the condensation module (2), and the top cover (39) is abutted against the base (21). At this time, one end of the exhaust gas inlet pipe (31), the exhaust gas outlet pipe (32) and the water injection pipe (33) are inserted into the head space bottle (1), the other end of the exhaust gas inlet pipe (31) is connected to the exhaust gas sampling pipe (9), and the other end of the exhaust gas outlet pipe (32) is connected to the exhaust gas absorption device (10); S4: cooling the base (21) and the headspace bottle (1) in the base (21) by means of a semiconductor temperature regulating sheet (22), so that the temperature in the headspace bottle (1) is between 0°C and 4°C; S5: Sampling is performed through the air pump (13) and the flow controller (12), and the exhaust gas sample enters the headspace bottle (1). The supersaturated gaseous water in the exhaust gas sample condenses and remains in the headspace bottle (1) due to the low temperature; S6: After the sampling is completed, the inlet end of the exhaust gas inlet pipeline (31) is closed, the exhaust gas inlet pipeline (31) is disconnected from the exhaust gas sampling tube (9), the refrigeration of the semiconductor thermostat (22) is stopped, the water injection pipe (33) and the pure water tank (6) are connected through the three-way valve (35), and pure water is pumped into the headspace bottle (1) through the peristaltic pump (34). At this time, the exhaust gas sample in the headspace bottle (1) is squeezed into the waste outlet pipeline by the pure water and flows into the adsorption tube (11); S7: Use a headspace bottle with a set volume of less than 40 mL, fill the headspace bottle (1) with pure water or when water drops appear at the outlet end of the waste gas outlet pipe (32), stop pumping pure water, close the outlet end switch of the waste gas outlet pipe (32), and disconnect the waste gas outlet pipe (32) from the adsorption tube (11); S8: Lift the passage module (3), take out the exhaust gas inlet pipe (31), the exhaust gas outlet pipe (32) and the water injection pipe (33) from the headspace bottle (1), take out the headspace bottle (1) and turn it upside down to check whether there are bubbles in the headspace bottle (1) and whether the silicone gasket is leaking; if bubbles are found, quickly open the screw cap (101), drip pure water, and quickly seal it; if the silicone hole is found to be too large and leaking, quickly open the screw cap (101) and replace the silicone gasket; S9: Analyze the water sample in the headspace bottle (1). Take 5 mL of the water sample in the sealed headspace bottle and analyze the VOCs in the water sample by a purge-trap instrument connected to a gas chromatograph. Take 2 mL of the remaining water sample and analyze the polar organic matter therein by a liquid chromatography-mass spectrometer. Then, extract the remaining water sample with an organic solvent, concentrate the extract to 1 mL, and analyze the non-polar organic matter therein by a gas chromatography-mass spectrometer.

9. The method for removing water and collecting target residues in organic matter monitoring according to claim 8, characterized in that: In step S6, if the waste gas sample in the headspace bottle (1) contains organic matter with very low solubility in water, the water injection pipe (33) and the methanol bottle (7) are connected via the three-way valve (35), and methanol is pumped into the headspace bottle (1) via the peristaltic pump (34).

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