An apparatus and method for moisture removal and target residue collection in organic matter monitoring

Abstract

The present invention discloses a device and method for moisture removal and target residue collection in organic matter monitoring, belonging to the technical field of environmental monitoring. It includes a headspace bottle, a condensation module and a passage module. 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. 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. The headspace bottle is refrigerated to condense gaseous water into liquid water and remain in the bottle. At the same time, by injecting pure water or methanol solution, the organic matter residue in the headspace bottle is dissolved into pure water (or methanol aqueous solution), avoiding the loss of VOCs. The structure of the present invention is simple and easy to operate, eliminating the error of sampling volume; at the same time, 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 waste 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, the "Determination of Volatile Organic Compounds in Exhaust Gas from Stationary Pollution Sources - Solid Phase Adsorption-Thermal Desorption / Gas Chromatography-Mass Spectrometry" (HJ 734-2014) applies to as many as 24 substances and is the most widely used.

[0003] However, during the collection of solid samples, the moisture content in the waste 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-water 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-water bath or semiconductor refrigeration dehumidification, their essence is refrigeration dehydration. During this dehydration process, when the waste gas sample enters the low-temperature region, not only gaseous water will condense, but also some high-concentration, high-boiling-point, and strongly polar organic compounds will condense or adsorb, resulting in sample loss and a lower monitoring result. Therefore, HJ 734-2014 requires using the purge and trap-gas chromatography / mass spectrometry (HJ 639) to analyze the collected condensed water and add the content of VOCs in it to the final result. However, in actual monitoring, this method has many problems:

[0005] 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;

[0006] 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 likely to cause sample loss;

[0007] After the condensed water is transferred into the purge sample bottle, it is generally necessary to fill it up to 40 mL with pure water. After checking for no air bubbles, it is sealed. This process is not carried out in a closed environment, which is likely to cause the volatilization loss of VOCs;

[0008] 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: according to the small impinger moisture collector in HJ 734, the minimum volume of each is 10 mL, and three in series is 30 mL. Then, for the first 30 mL of gas during sample collection, it is all the gas originally present in the device. When collecting 300 mL, the truly 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;

[0009] The existing methods for dehydration and moisture collection have complex operation processes and are not suitable for on-site monitoring.

[0010] 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

[0011] 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.

[0012] The purpose of the present invention is achieved through the following technical solutions:

[0013] A device for moisture removal and target residue collection in organic matter monitoring includes a headspace vial, a condensation module, and a passage module:

[0014] The top of the headspace vial is provided with a screw cap, the middle of the screw cap is provided with a silicone gasket, and a PTFE film is provided on the side of the silicone gasket facing the inside of the bottle;

[0015] 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;

[0016] 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 vial is surrounded by the installation cavity and the placement cavity;

[0017] The upper end of the top cover is provided with an exhaust gas inlet pipeline, an exhaust gas outlet pipeline and a water injection pipe that communicate with the installation cavity. 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 the 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;

[0018] The exhaust gas sampling pipe extends into the exhaust gas pipeline for sampling. A temperature adjustment device is arranged outside the exhaust gas sampling pipe. The exhaust gas absorption device sequentially includes an adsorption pipe, a filter, a flow controller and an air pump.

[0019] Further, the insertion ends of the exhaust gas inlet pipeline, the exhaust gas outlet pipeline and the water injection pipe are provided with syringe needles.

[0020] Further, a circle of through holes is arranged outside the syringe needles of the exhaust gas inlet pipeline and the exhaust gas outlet pipeline, and the through holes are close to the needle tips of the syringe needles.

[0021] Further, both the base and the top cover are made of aluminum alloy material. An insulating layer is arranged outside 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 arranged at the bottom of the base.

[0022] Further, a radiator is arranged on the side of the semiconductor temperature regulating sheet away from the base.

[0023] Further, the pure water tank and the methanol bottle are of a sealed structure. One-way valves are arranged at the tops of the pure water tank and the methanol bottle. Activated carbon adsorption pipes and organic matter filter membranes are arranged at the air inlets of the one-way valves.

[0024] Further, a guide rail is arranged between the top cover and the base, and the top cover is detachably connected to the base through the guide rail.

[0025] A method for removing moisture and collecting target residue in organic matter monitoring includes the following steps:

[0026] S1: The headspace bottle is filled with high-purity nitrogen and sealed with a screw cap;

[0027] S2: The headspace bottle is placed 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;

[0028] S3: Move the passage module downward and 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;

[0029] S4: Cool the base and the headspace bottle inside the base through the semiconductor temperature control chip, so that the temperature inside the headspace bottle is between 0 and 4 °C;

[0030] S5: Sample 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;

[0031] 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 control chip, 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;

[0032] S7: Fill the headspace bottle with pure water. When there are water droplets at the outlet end of the waste gas outlet pipeline, stop pumping pure water, close the switch at the outlet end of the waste gas outlet pipeline, and disconnect the waste gas outlet pipeline from the adsorption tube.

[0033] S8: Lift the passage module, take out the waste gas inlet pipeline, the waste gas outlet pipeline, and the water injection pipe from the headspace bottle. After taking out the headspace bottle, invert it, and check whether there are bubbles in the headspace bottle and whether the silica gel gasket leaks; if bubbles are found, quickly open the screw cap, drip pure water, and seal it quickly; if it is found that the silica gel hole is too large and leaks, quickly open the screw cap and replace the silica gel gasket;

[0034] S9: Analyze the water sample in the headspace bottle. Take 5 mL from the water sample in the sealed headspace bottle and analyze the VOCs in the water sample through a purge and trap analyzer connected to a gas chromatograph; take 2 mL from the remaining water sample and analyze the polar organic compounds in it with a liquid chromatography - mass spectrometer; then extract the remaining water sample with an organic solvent by liquid - liquid extraction, concentrate the extract to 1 mL, and analyze the non - polar organic compounds in it by a gas chromatography - mass spectrometer.

[0035] Further, in step S6, if there are organic compounds with very low solubility in water in the waste gas sample of the headspace bottle, connect the water injection pipe and the methanol bottle through the three - way valve, and pump methanol into the headspace bottle through the peristaltic pump.

[0036] The beneficial effects of the present invention are:

[0037] Prevent VOCs from volatilizing and collecting residual organic matter: This device avoids the direct contact between 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 VOCs dissolved in water and semi-volatile organic compounds (SVOCs) with low volatility remaining on the inner wall.

[0038] Reduce residual loss: By filling the headspace vial with pure water or an aqueous methanol solution, the organic matter residues in the headspace vial are dissolved therein, avoiding the loss of organic matter such as VOCs during transfer and other processes.

[0039] Device structure optimization: This device has a simple structure, is easy to operate, minimizes dead volume as much as possible, greatly reduces the error caused by the sampling volume, and further ensures the accuracy of monitoring data.

[0040] Accurately determine the content of VOCs: Measure 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, significantly improving the accuracy of the data. Specifically, analyze the VOCs in the water sample through a purge and trap instrument connected to a gas chromatograph; analyze the organic matter with certain polarity and high boiling point in the water sample with the help of a liquid chromatography-mass spectrometer; analyze the non-polar and high-boiling organic matter in the water sample using a gas chromatography-mass spectrometer.

[0041] Can be used for the monitoring of SVOCs: In addition to analyzing VOCs, it can also determine SVOCs. Such substances have high boiling points and low 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

[0042] Figure 1 It is a schematic diagram of a device for removing moisture and collecting target residue in the monitoring of organic matter according to the present invention;

[0043] Figure 2 It is a schematic diagram of the headspace vial in the present invention;

[0044] Figure 3 It is a top view of the condensation module in the present invention;

[0045] Figure 4 It is a schematic diagram of the condensation module and the passage module in the present invention;

[0046] Figure 5 It is a schematic diagram of the syringe in the present invention;

[0047] Figure 6 It is a schematic diagram of step S2 in Embodiment 2 of the present invention;

[0048] Figure 7Schematic diagram of step S3 in Embodiment 2 of the present invention;

[0049] Figure 8 Schematic diagram of step S4 in Embodiment 2 of the present invention;

[0050] Figure 9 Schematic diagram of step S5 in Embodiment 2 of the present invention;

[0051] Figure 10 Schematic diagram of adding pure water in step S6 in Embodiment 2 of the present invention;

[0052] Figure 11 Schematic diagram of adding methanol in step S6 in Embodiment 2 of the present invention;

[0053] Figure 12 Schematic diagram of step S7 in Embodiment 2 of the present invention;

[0054] Figure 13 Schematic diagram of step S8 in Embodiment 2 of the present invention;

[0055] In the figure, 1 - headspace vial, 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 implementation manners

[0056] Next, the technical solutions of the present invention will be clearly and completely described 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. Embodiment

[0057] Refer to Figures 1-5 , the present invention provides a technical solution:

[0058] A device for moisture removal and target residue collection in organic matter monitoring, comprising a headspace vial 1, a condensation module 2 and a passage module 3:

[0059] The top of the headspace vial 1 is provided with a screw cap 101, the middle of the screw cap 101 is hollow and provided with a silica gel gasket, and a PTFE film is provided on the side of the silica gel gasket facing the inside of the bottle.

[0060] Through the structure of the headspace vial 1, the headspace vial 1 is pre-filled with high-purity nitrogen gas and sealed with a screw cap 101. The middle part of the screw cap 101 is a hollow structure, and a silica gel gasket is provided inside the screw cap 101. The silica gel gasket is installed inside the screw cap 101 and will not fall out, and the hollow part of the screw cap 101 is shielded and sealed by the silica gel gasket. A PTFE film is provided on the side of the silica gel gasket close to the inside of the headspace vial 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 substances and causes residues.

[0061] 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.

[0062] The sealed headspace vial 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 vial 1, so that the headspace vial 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 vial 1, and the screw cap 101 part of the headspace vial 1 is exposed outside the placement cavity 24 for convenient operation.

[0063] 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 vial 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, and a heat insulation layer is provided at the position of the base 21 where the semiconductor temperature control chip 22 is not provided to keep the temperature in the placement cavity 24 stable.

[0064] Furthermore, a drain hole 25 communicating with the placement cavity 24 is provided at the bottom of the base 21. When the headspace vial 1 is cooled, if there is liquefied frost water inside the placement cavity 24 and outside the headspace vial 1, it will flow out from the drain hole 25.

[0065] 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 matched, the headspace vial 1 is surrounded by the installation cavity 36 and the placement cavity 24.

[0066] After the headspace vial 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 sealed structures, and one-way valves 8 are provided at the tops of the pure water tank 6 and the methanol bottle 7. Through the one-way valves 8, the gas can only flow into the tank (bottle) from the outside. 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).

[0067] Move the top cover 39 towards the base 21. Since the pipeline connected to the upper part of the top cover 39 is relatively long, it is convenient for the top cover 39 to move onto the base 21. The headspace vial 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, and an insulating layer is provided on the outer surface to conduct heat and keep warm the upper part of the headspace vial 1.

[0068] 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.

[0069] An exhaust gas inlet pipeline 31, an exhaust gas outlet pipeline 32, and a water injection pipe 33 that communicate 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 vial 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 vial 1, and the other end of the exhaust gas outlet pipeline 32 is detachably connected to the exhaust gas absorption device 10.

[0070] The exhaust gas inlet pipeline 31, the exhaust gas outlet pipeline 32, and the water injection pipe 33 pass through the top cover 39 respectively. The exhaust gas inlet pipeline 31 and the exhaust gas outlet pipeline 32 are in an L shape, and a switch joint is provided on one side of the exhaust gas inlet pipeline 31 and the exhaust gas outlet pipeline 32 outside the top cover 39. The corresponding flow path can be closed through the switch joint.

[0071] One end of the water injection pipe 33 extends into the bottom of the headspace vial 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.

[0072] 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.

[0073] Furthermore, syringe needles 37 are provided at the insertion ends of the exhaust gas inlet pipeline 31, the exhaust gas outlet pipeline 32, and the water injection pipe 33.

[0074] When the passage module 3 cooperates with the condensation module 2, through the setting of the syringe needles 37 at the ends, it is convenient for the exhaust gas inlet pipeline 31, the exhaust gas outlet pipeline 32, and the water injection pipe 33 to pierce the silicone gasket on the screw cap 101, and then insert the exhaust gas inlet pipeline 31, the exhaust gas outlet pipeline 32, and the water injection pipe 33 into the headspace vial 1. At the same time, the silicone gasket has a certain elasticity. When the syringe needle 37 pierces the silicone gasket, the silicone gasket will shrink the notch and then tighten around the pipeline to achieve a sealing effect.

[0075] Further, a circle of through holes 38 are provided at the needle ends of the syringe needles 37 of the exhaust gas inlet pipeline 31 and the exhaust gas outlet pipeline 32, and the through holes 38 are close to the needles of the syringe needles 37. The through holes 38 are designed in such a way that they are not easily blocked by silica gel debris; and after the exhaust gas enters the headspace vial 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), enabling more efficient heat exchange and facilitating the condensation of water.

[0076] The exhaust gas sampling tube 9 extends into the exhaust gas pipeline for sampling, and a temperature regulating device is provided outside the exhaust gas sampling tube 9. The exhaust gas absorption device 10 sequentially includes an adsorption tube 11, a filter, a flow controller 12 and a gas pump 13.

[0077] After the top cover 39 and the base 21 are closed, the exhaust gas sampling tube 9 is communicated with the exhaust gas inlet pipeline 31, and one end of the adsorption tube 11 is communicated with the exhaust gas outlet pipeline 32. At this time, when the gas pump 13 is started, the exhaust gas can be drawn from the exhaust gas sampling tube 9 into the headspace vial 1, and at the same time, the exhaust gas also flows along the flow path into the adsorption tube 11 for adsorption. The flow rate can be adjusted by the flow controller 12, and a filter is provided at the front end of the flow controller 12 to prevent the exhaust gas from damaging the flow controller 12.

[0078] During the sampling process, the exhaust gas is cooled by the condensation module 2, and the gaseous water in the headspace vial 1 will condense into liquid and remain in the headspace vial 1.

[0079] After the sampling is completed, pure water is slowly added to the headspace vial 1 through the peristaltic pump 34. The gas in the headspace vial 1 will be squeezed into the exhaust gas outlet pipeline 32 and then flow into the adsorption tube 11. The VOCs in the exhaust 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.

[0080] After the headspace vial 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 vial 1 is removed for subsequent analysis of the water sample.

[0081] Through the device of the present application, the sample collection and condensation can be quickly completed, the loss of VOCs due to volatilization is reduced, the error of the sampling volume is eliminated, and not only the VOCs in the exhaust gas can be analyzed, but also the semi-volatile organic compounds (SVOCs) can be determined. Such substances have weak volatility. When the high-temperature exhaust gas enters the dehydrator, due to the sharp temperature drop, they will be adsorbed or condensed on the inner wall of the dehydrator. This device can dissolve them in water or methanol aqueous 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 the semi-volatile organic compounds, that is, the SVOCs could not be analyzed. Example

[0082] Refer to Figures 1-13 , the present invention provides a technical solution:

[0083] A method for moisture removal and target residue collection in organic matter monitoring, comprising the following steps:

[0084] 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.

[0085] 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.

[0086] S3: As Figure 7 shown, the passage module 3 is moved downward and installed with the condensation module 2. 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.).

[0087] S4: As Figure 8 shown, the base 21 and the headspace vial 1 in the base 21 are cooled by a semiconductor temperature control chip 22, so that the temperature in the headspace vial 1 is between 0 and 4 °C. At the same time, a temperature sensor can be set in the placement cavity 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 control chip 22. If a stronger water removal effect is pursued, it can also be condensed into ice. Without overly pursuing the refrigeration effect, with a common power and size of the refrigeration chip, the lowest temperature of the condensation module 2 in this design can reach -20 °C.

[0088] For samples with good water solubility, high boiling point, and high concentration, when the moisture content exceeds 3%, the above-mentioned types of organic matter will have a relatively obvious loss in a conventional water removal device. 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.

[0089] S5: As Figure 9As shown, when the temperature of the condensation module 2 reaches the set value, the switch joints of the waste gas inlet pipeline 31 and the waste gas outlet pipeline 32 are opened to open the flow path, and sampling is carried out 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 bottle 1, due to the low temperature, the gaseous water will condense into liquid and remain in the headspace bottle 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 bottle 1 is generally lower than 0.8% (v / v) at 0 - 4°C, and 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. At present, the method of HJ 734 is used to analyze the volatile organic compounds in the waste gas from fixed 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, there are more than 100 compounds that can be trapped and desorbed.

[0090] At the same time, high-boiling-point, high-concentration organic compounds and high-concentration, water-soluble organic compounds such as alcohols, methanol, ethanol, propanol, etc. will partially accumulate in the headspace bottle 1.

[0091] At the same time, the sampling volume of this application can be in the range of 300 mL - 2000 mL, and the waste gas with a temperature up to 200°C can be sampled, or the waste gas with a moisture content of 1% - 30% can be sampled. The sampling range of this application is wide and the applicability is good.

[0092] S6: As Figure 10 shown, after sampling is completed, the inlet end of the waste gas inlet pipeline 31 is closed, the waste gas inlet pipeline 31 is disconnected from the waste gas sampling tube 9, the semiconductor temperature control chip 22 stops refrigerating, 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 a flow rate of 20 mL / min. The organic compounds 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 speed to be equal to the pure water addition speed. At the same time, with the addition of pure water, the waste gas sample in the headspace bottle 1 is squeezed into the waste outlet pipeline and flows into the adsorption tube 11 at this time, so that the VOCs are adsorbed therein.

[0093] As Figure 11 shown, in step S6, if there are organic compounds with poor water solubility and high concentration in the waste gas sample of the headspace bottle 1, the water injection pipe 33 and the methanol bottle 7 are connected through the three-way valve 35, and methanol is pumped 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 compounds. The rate of adding methanol is controlled at 5 mL / min, and the addition amount is between 2 - 10 mL. After adding the set amount of methanol, the three-way valve 35 is switched, and pure water is continued to be added.

[0094] If the waste gas mainly contains organic substances with poor water solubility, high boiling points, and high concentrations, such as high molecular weight benzene series, hydrocarbons, chlorinated benzenes, polycyclic aromatic hydrocarbons, PFASs, etc., when 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 substance of concern is not VOCs, methanol can also be added entirely without adding pure water. In this case, after the headspace vial 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.

[0095] S7: As Figure 12 shown, fill the headspace vial 1 with pure water. When there are water droplets at the outlet end of the waste gas outlet pipe 32, stop pumping pure water, close the switch at the outlet end of the waste gas outlet pipe 32, and disconnect the waste gas outlet pipe 32 from the adsorption tube 11. Since the headspace vial 1 uses 40 mL, when the injected pure water is close to 40 mL, close the switch joint at one end of the waste gas outlet pipe 32 and remove the adsorption tube 11, etc. If it is found that the headspace vial 1 may not be fully filled with pure water, the switch joint of the waste gas outlet pipe 32 can be opened again, and pure water is 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 waste gas outlet pipe 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 vial 1. At this time, the organic matter residues in the headspace vial 1 are dissolved in pure water (or methanol aqueous solution).

[0096] S8: As Figure 13 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 vial 1. After taking out the headspace vial 1, invert it to confirm whether there are bubbles in the headspace vial 1 and whether the silica gel gasket leaks; if bubbles are found, quickly open the screw cap 101, drop in pure water, and quickly seal it; if it is found that the silica gel hole is too large and leaks, quickly open the screw cap 101 and replace the silica gel gasket;

[0097] When the syringe 37 of the passage module 3 is removed from the headspace vial 1, the silica gel gasket of the headspace vial 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.

[0098] S9: Analyze the water sample in the headspace vial 1. The headspace vial is transferred as a whole after being sealed and placed on the detection instrument. Take 5 mL from the water sample in the sealed headspace vial and analyze the VOCs in the water sample by connecting a purge and trap instrument to a gas chromatograph or by connecting to a gas chromatography-mass spectrometer for analysis; take 2 mL from the remaining water sample and analyze the polar organic compounds therein using 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 therein using 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.

[0099] 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 techniques or knowledge in related fields. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. A device for moisture removal and target residue collection in organic matter monitoring, characterized in that: It includes a headspace vial (1), a condensation module (2) and a passage module (3): The top of the headspace vial (1) is provided with a screw cap (101). The middle of the screw cap (101) is provided with a silica gel gasket, and a PTFE film is provided on the side of the silica gel gasket facing the inside of the bottle; 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); 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, the headspace vial (1) is surrounded by the installation cavity (36) and the placement cavity (24); At the upper end of the top cover (39), there are an exhaust gas inlet pipeline (31), an exhaust gas outlet pipeline (32) and a water injection pipe (33) communicated with the installation cavity (36). One end of the exhaust gas inlet pipeline (31) extends into the bottom of the headspace vial (1), and the other end of the exhaust gas inlet pipeline (31) is detachably connected to the outlet of an exhaust gas sampling pipe (9). One end of the exhaust gas outlet pipeline (32) extends into the top of the headspace vial (1), and the other end of the exhaust gas outlet pipeline (32) is detachably connected to an exhaust gas absorption device (10). One end of the water injection pipe (33) extends into the bottom of the headspace vial (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 a three-way valve (35). A peristaltic pump (34) is provided between the three-way valve (35) and the water injection pipe (33); The exhaust gas sampling pipe (9) extends into the exhaust gas pipeline for sampling. A temperature adjustment device is provided outside the exhaust gas sampling pipe (9). The exhaust gas absorption device (10) sequentially includes an adsorption tube (11), a filter, a flow controller (12) and an air pump (13).

2. The device for moisture removal and target residue collection in organic matter monitoring according to claim 1, wherein: Needles (37) are provided at the insertion ends of the exhaust gas inlet pipeline (31), the exhaust gas outlet pipeline (32) and the water injection pipe (33).

3. The device for moisture removal and target residue collection in organic matter monitoring according to claim 2, characterized in that: A circle of through holes (38) is provided outside the needles (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 tips of the needles (37).

4. The device for moisture removal and target residue collection in organic matter monitoring according to claim 1, wherein: Both the base (21) and the top cover (39) are made of aluminum alloy material. An insulating layer is provided on the outside of the top cover (39). The radii of the placement cavity (24) and the installation cavity (36) are 0.5 mm larger than the radius of the headspace vial (1). A drain hole (25) communicated with the placement cavity (24) is provided at the bottom of the base (21).

5. The device for moisture removal and target residue collection in organic matter monitoring according to claim 1, characterized in that: A radiator (23) is provided on the side of the semiconductor temperature control chip (22) away from the base (21).

6. The device for moisture removal and target residue collection in organic matter monitoring according to claim 1, wherein: The pure water tank (6) and the methanol bottle (7) are of a sealed structure. Check valves (8) are provided at the tops 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 inlets of the check valves (8).

7. The device for moisture removal and target residue collection 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) through the guide rail.

8. A method for moisture removal and target residue collection in organic matter monitoring, comprising the device for moisture removal and target residue collection in organic matter monitoring according to any one of claims 1-7, characterized in that: It includes the following steps: S1: The headspace bottle (1) is filled with high-purity nitrogen and sealed with a screw cap (101). S2: The headspace bottle (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 the closed state. S3: 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) are inserted into the headspace bottle (1), the other end of the waste gas inlet pipeline (31) is connected to the waste gas sampling pipe (9), and the other end of the waste gas outlet pipeline (32) is connected to the waste gas absorption device (10). S4: The base (21) and the headspace bottle (1) inside the base (21) are cooled by the semiconductor temperature control chip (22) so that the temperature inside the headspace bottle (1) is between 0 and 4 °C. S5: Sampling is carried out through the air pump (13) and the flow controller (12), and the waste gas sample enters the headspace bottle (1). The supersaturated gaseous water in the waste gas sample will condense and remain in the headspace bottle (1) due to the low temperature. S6: After sampling, the inlet end of the waste gas inlet pipeline (31) is closed, the waste gas inlet pipeline (31) is disconnected from the waste gas sampling pipe (9), the cooling of the semiconductor temperature control chip (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 waste 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 40 mL. Fill the headspace bottle (1) with pure water or stop pumping pure water when there are water droplets at the outlet end of the waste gas outlet pipeline (32). Close the outlet end switch of the waste gas outlet pipeline (32) and disconnect the waste gas outlet pipeline (32) from the adsorption tube (11). S8: Lift the passage module (3), take out the waste gas inlet pipeline (31), the waste gas outlet pipeline (32) and the water injection pipe (33) from the headspace bottle (1). After taking out the headspace bottle (1), invert it to confirm whether there are bubbles in the headspace bottle (1) and whether the silica gel gasket leaks. If bubbles are found, quickly open the screw cap (101), drip in pure water, and quickly seal it. If it is found that the silica gel hole is too large and leaks, quickly open the screw cap (101) and replace the silica gel gasket. S9: Analyze the water sample in the headspace bottle (1). Take 5 mL from the water sample in the sealed headspace bottle and analyze the VOCs in the water sample through a purge and trap instrument connected to a gas chromatograph. Take 2 mL from the remaining water sample and analyze the polar organic substances in it with a liquid chromatography-mass spectrometer. Then, liquid-liquid extraction is carried out on the remaining water sample with an organic solvent, and the extract is concentrated to 1 mL, and the non-polar organic substances in it are analyzed by a gas chromatography-mass spectrometer.

9. The method for moisture removal and target residue collection in organic matter monitoring according to claim 8, characterized in that: In step S6, if there are organic substances with very low solubility in water in the waste gas sample of the headspace vial (1), the water injection pipe (33) and the methanol bottle (7) are connected through a three-way valve (35), and methanol is pumped into the headspace vial (1) by a peristaltic pump (34).

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