CN115598258A - Enrichment and desorption device for organic compounds in the volatile range of C8-C40 in the atmospheric particle phase - Google Patents

Abstract

The application provides a device for enrichment and desorption of organic matter within the volatile range of C8-C40 in the atmospheric particle phase, including: a tube body, a desorption tube and a transfer tube; mouth and gas outlet; in the sampling direction of the organic matter, a filter membrane, a heating membrane and a support structure are sequentially arranged inside the tube body; a desorption tube, one side of which is welded to the side surface of the tube body , the other side of which extends radially outward along the tube body; the transmission tube, the transmission tube is L-shaped. The device is made of quartz and is integrated with a "sandwich" structure of quartz fiber filter membrane-patch heating plate-quartz support net. It has a compact structure, low cost, and can realize direct contact heating of the filter membrane, ensuring that The uniform, rapid and precise temperature rise and high-efficiency analysis of organic matter at the quartz filter membrane avoid the insufficient thermal desorption of C35‑C40 high-carbon organic matter.

Description

Enrichment and desorption device for organic compounds in the volatile range of C8-C40 in the atmospheric particle phase

technical field

The application belongs to the technical field of environmental monitoring, and relates to an enrichment and desorption device for organic matter within the volatile range of C8-C40 in the atmospheric particle phase.

Background technique

Atmospheric organic aerosol is an important part (20%-50%) of fine particulate matter (PM2.5). The composition of organic matter in the particles is complex, and the concentration in the atmosphere is low, and the physical and chemical properties vary greatly. At present, it can be accurately quantified Species only account for 10% to 40% of the total mass of organic matter. Atmospheric organic aerosols contain many substances harmful to the human body, such as polycyclic aromatic hydrocarbons, nitrosamine compounds, and other chlorine-containing organic compounds, which are carcinogenic, teratogenic, and mutagenic to the human body. Organic aerosols also have a significant impact on atmospheric visibility and are a major contributor to acid deposition and atmospheric photochemical smog. In addition, some organic aerosol compounds have an important source indicator function, such as polycyclic aromatic hydrocarbons (PAHs), which are mainly produced by incomplete combustion of fossil fuels, biomass, etc.; hopane compounds are biomarkers of fuel oil, coal and lubricants , can be used to identify the source of motor vehicle emissions; normal alkanes can be used as markers for fossil fuel utilization and biological source emissions, and the analysis of these tracers can determine the source characteristics of particulate matter.

As an important part of atmospheric fine particles, organic aerosols have a non-negligible impact and harm on atmospheric climate, living environment and human health. Therefore, accurate measurement of them and determination of their pollution characteristics are a key step in our prevention and control of pollution. At present, the measurement of organic molecular components of particulate matter at home and abroad is mainly divided into two methods: offline measurement and online measurement. Offline sampling methods are basically based on membrane samplers or hierarchical impact samplers such as microporous uniform deposition multi-stage impact samplers. Take the sampler after sampling to the laboratory for a series of off-line post-processing (including solvent extraction, pre-concentration and derivatization methods) and testing. The species that can be identified by offline measurement are limited, and the pre-processing process is complicated, the time resolution is low, and the change of atmospheric composition cannot be reflected in real time. Online measurement methods mainly have the advantages of high time resolution, automation, saving manpower and time costs, and real-time reflection of atmospheric components, etc., mainly including thermal desorption gas chromatography (thermal desorption aerosol GC/MS-FID, TAG), chemical ionization mass spectrometry ( chemical ionization mass spectrometry (CIMS) and proton transfer reaction mass spectrometry (proton transfer reaction mass spectrometry, PTR-MS), etc.

Gas chromatography based on thermal desorption has the advantages of simple operation and high sample utilization, and has been used for the determination of trace organic compounds in atmospheric particulate matter. The current commercialized equipment is mainly based on the thermal desorption gas chromatography TAG instrument built by Williams et al. in 2006, which is mainly used for automatic, high-time resolution collection and GC-MS analysis of organic compounds in atmospheric particles. Afterwards, based on TAG, the pretreatment and separation system were improved and designed to different degrees at home and abroad, which improved its detection and separation performance.

However, the current online collection modules for particulate organic matter are generally based on non-replaceable passivated stainless steel filter membranes or quartz fiber filter membrane enrichment modules made of stainless steel that need to be passivated inside. The passivation treatment of the acquisition module generally needs to be obtained from the American Restek Company for internal deactivation special operations. This passivation step increases the cost of the equipment to a large extent and reduces the time efficiency. In addition, at present, the direct enrichment of the collected organic matter at the head of the chromatographic column or the secondary enrichment only relying on temperature will largely lead to the penetration of highly volatile C8-C14 substances in the system, resulting in the loss of The measurement information of active substances reduces the richness and comprehensiveness of the multi-species measurement of the instrument.

Contents of the invention

In order to solve the problems in the prior art and to expand the monitoring capability of the highly volatile and low-carbon organic matter collected from particulate matter, the application provides a particulate matter collection system made of quartz and a system based on adsorbent capture and low-temperature capture. The dual-focus system and the use of commercial GCMS for separation and detection can extend the particle detection species to a volatility range from C8 to C40. The acquisition part based on quartz material does not need passivation pretreatment inside, which reduces the preparation time and instrument cost in the early stage, and uses a patch heater that is close to the quartz filter membrane to contact the enriched filter membrane. Heating up the temperature ensures the efficient desorption of organic matter; the species of particulate organic matter is complex, the boiling point span is large, and the high-carbon matter can be captured only by low temperature due to its high viscosity, while the low-carbon C8-C14 matter is easier in the In order to realize the effective measurement of the concentration of highly volatile particulate organic matter, the sampled organic matter is focused on a low-temperature adsorbent, then desorbed by rapid temperature rise, and finally separated and detected by GCMS. Sorbent focusing not only expands the species range of organic matter to be measured, but also avoids tailing of subsequent measurement peaks. The measurement time resolution of the system can be adjusted for different sampling times according to the pollution status of atmospheric particulate matter, generally in the range of 30-90min; the whole device is compact in structure and easy to operate, and can realize online monitoring of atmospheric particulate organic matter with an hourly resolution.

The technical scheme of this application is as follows:

1. An enrichment and desorption device for organic matter in the volatile range of C8-C40 in the atmospheric particle phase, comprising: a tube body, a desorption tube and a transfer tube;

The tube body, the two sides of the tube body are the sample inlet and the gas outlet respectively;

In the direction of the sampling of the organic matter, a filter membrane, a heating membrane and a support structure are sequentially arranged inside the tube body;

A desorption tube, one side of which is welded to the side surface of the tube body, and the other side extends radially outward along the tube body;

The transmission pipe is L-shaped, and one side of the transmission pipe is welded to the support structure, wherein one edge of the L-shaped transmission pipe extends along the inner wall of the pipe, and the other side of the L-shaped pipe is welded from the pipe body to the support structure. One side surface of the desorption tube is opposite to the other side surface protruding;

The support structure, the desorption tube and the transfer tube are arranged at different positions of the tube body in the direction of the sampling of the organic matter.

2. The enrichment and desorption device according to item 1,

In the sampling direction of the organic matter, the support mechanism is arranged upstream of the desorption pipe, and the transfer pipe is arranged downstream of the desorption pipe;

Preferably, the ratio of the distance between the support structure and the desorption tube to the total length of the tube body is (0.3-1):6;

Further preferably, the ratio of the distance between the support structure and the transmission pipe to the total length of the pipe body is (1-3):6;

More preferably, the ratio of the distance between the transfer tube and the sample inlet to the total length of the tube body is (3-4):6.

More preferably, the ratio of the distance between the desorption tube and the injection port to the total length of the tube body is (1.5-3.5):6.

3. The enrichment-desorption device according to item 2,

In the sampling direction of the organic matter, the desorption pipe is arranged upstream of the support mechanism, and the transfer pipe is arranged downstream of the support mechanism;

Preferably, the ratio of the distance between the support structure and the desorption tube to the total length of the tube body is (0.3-1):6;

Further preferably, the ratio of the distance between the support structure and the transmission pipe to the total length of the pipe body is (1-3):6;

More preferably, the ratio of the distance between the transfer tube and the sample inlet to the total length of the tube body is (3-4):6.

More preferably, the ratio of the distance between the desorption tube and the injection port to the total length of the tube body is (0.5-2.5):6.

4. The enrichment and desorption device according to item 1,

The enrichment-desorption device also includes a liner, the liner is arranged inside the tube body and is located between the sample inlet and the filter membrane.

5. The enrichment-desorption device according to item 1,

The enrichment-desorption device also includes a patch temperature sensor, the patch temperature sensor is located in the middle of the filter membrane and the heating membrane, and is close to the side of the tube body with the transfer tube;

Preferably, the wires connected to the heating membrane and the wires connected to the patch temperature sensor are located in the transmission tube.

6. The enrichment-desorption device according to item 1,

Both sides of the pipe body are sealed with a first O-ring or a polytetrafluoroethylene ferrule joint. Preferably, the first O-ring is made of fluororubber or nitrile rubber;

The desorption tube is sealed with a second O-ring, preferably, the second O-ring is made of polyimide;

The transmission pipe is sealed with a sealant, preferably, the material of the sealant is inorganic ceramic material.

7. The enrichment-desorption device according to item 1,

The filter membrane is a quartz filter membrane.

8. The enrichment and desorption device according to item 1,

The enrichment-desorption device also includes a refrigeration unit arranged outside the tube body;

Preferably, the refrigeration unit is a fan.

9. A device for enrichment and desorption of organic matter within the volatile range of C8-C40 in the atmospheric particle phase, characterized in that it comprises the enrichment and desorption device described in any one of items 1-8.

10. The enrichment-desorption device according to item 9, further comprising high and low temperature components;

The high and low temperature components include a high temperature module, a low temperature module and a high and low temperature switching module.

11. The enrichment-desorption device according to item 10, wherein,

The high temperature module includes an adsorption tube and a resistance wire wound outside the adsorption tube, and the inside of the adsorption tube is filled with Tenax series adsorbents;

Preferably, a layer of insulating sleeve is further included between the adsorption tube and the resistance wire, and the insulating sleeve is wrapped around the periphery of the adsorption tube;

Further preferably, the high temperature module further includes a protection unit wrapped around the resistance wire;

More preferably, the high temperature module further includes a temperature sensor, and the temperature sensor is arranged outside the adsorption tube body and between the insulating sleeve and the adsorption tube.

12. The enrichment-desorption device according to item 10, wherein,

The low-temperature module includes a cooling plate and a metal block. The metal block is composed of two symmetrical sub-metal blocks with a semicircular groove in the center and can be opened and closed. The adsorption tube can be attached to the two symmetrical sub-metal blocks. in the groove formed;

Preferably,

The cold end of the refrigerating plate is closely attached to the metal block.

13. The enrichment-desorption device according to item 10, wherein,

The high and low temperature switching module includes a pneumatic drive device, and the pneumatic drive device realizes the switch between the high temperature mode and the low temperature mode of the adsorption tube by separating and closing the low temperature sub-metal block;

Preferably,

When the pneumatic drive device is supplied with carrier gas, the two symmetrical sub-metal blocks move relative to each other, so that there is a gap between the two symmetrical sub-metal blocks and the adsorption tube, and the heating module is controlled to work in a high-temperature mode ;

When the pneumatic device is not supplied with carrier gas, the two symmetrical sub-metal blocks move toward each other, so that the two symmetrical sub-metal blocks adhere to the adsorption tube, and the heating module is controlled to stop working, and is in a low-temperature mode.

14. Use the enrichment and desorption device described in any one of items 1-8 or the enrichment and desorption device described in any one of items 9-13 for organic compounds in the C8-C40 volatility range in the atmospheric particle phase method in online measurement.

15. The method according to clause 14, comprising

Sampling step, purging step, focusing enrichment step, measurement step; wherein,

Sampling step: passing the sample to be detected into the enrichment desorption device, so that the particulate phase organic matter is enriched in the enrichment desorption device;

Purging step: purging the enrichment-desorption device and its transmission route or the enrichment-desorption device and its transmission route with carrier gas to remove excess gas;

Focusing enrichment step: desorb the particulate phase organic matter adsorbed in the enrichment desorption device and enter the enrichment desorption device;

Measurement steps: desorb the organic matter in the particle phase adsorbed in the enrichment-desorption device, and separate and measure the organic matter in the particle phase.

Compared with the prior art, the beneficial effects of the present application are:

(1) The quartz fiber filter membrane particle enrichment thermal desorption module of the present application is based on the quartz medium as the carrier. The device integrates the "sandwich" structure of the quartz fiber filter membrane-patch type heater-quartz support net, Nested into the quartz tube, not only avoids the need for additional passivation pretreatment steps in the past with stainless steel as the medium, but also reduces the instrument development time and equipment costs to a certain extent. In addition, the "sandwich" enrichment thermal desorption structure can realize direct contact heating of the filter membrane, which is different from the current heating form that heats the quartz tube and then conducts to the filter membrane. This contact heating can ensure the enrichment in the The rapid and accurate temperature rise and high-efficiency analysis of organic matter in the quartz filter membrane avoid the insufficient thermal desorption of C35-C40 high-carbon organic matter.

(2) In order to expand the measurement of particulate organic low-carbon substances, a dual-focus module based on adsorbent enrichment and low-temperature enrichment was designed after filter membrane sampling, and low-carbon low-carbon organic substances of C8-C14 that are easy to lose Enrichment, to ensure that it can enter the GCMS module without loss. The focusing module adopts a pneumatic control method, which can quickly switch between low-temperature enrichment and high-temperature analysis of organic matter, avoiding the temperature ambiguity of high-low temperature conversion, and can meet the temperature range requirements of -40°C to 320°C. This not only expands the monitoring range of the system, but also avoids the peak tailing phenomenon of subsequent sample peaks due to the instantaneous temperature rise desorption.

(3) The gas circuit switching of the entire equipment only relies on the electric passivation three-way ball valve and the electric three-way valve at the front end of the gas circuit, reducing the use of high-temperature four-way valves or high-temperature six-way valves that are easy to wear and leak. The entire equipment is small in design and compact in structure, and each component can be designed as a separate modular system. The time resolution of the entire system is 30-90 minutes, which can realize the hourly resolution online measurement of atmospheric particulate organic matter.

(4) According to the physical and chemical properties of atmospheric particulate organic matter, the self-designed quartz medium thermal desorption enrichment-adsorbent low-temperature double-focusing technology module, combined with gas chromatography-mass spectrometry, control system and data processing software system, can analyze atmospheric particulate matter. On-line measurement of molecular level concentration of organic compounds within the volatile range of C8-C40 forms a high-sensitivity online measurement system for low-concentration particle-phase organic compounds in the atmosphere.

(5) The enrichment and desorption device in this application adopts a direct heating method that can efficiently heat up the filter membrane separately, and has little influence on the temperature of the tube body, so that the sample inlet and gas outlet on both sides of the tube body The temperature is as low as 50°C, and ordinary O-rings or ferrule joints can be used for sealing, which saves costs.

Description of drawings

Fig. 1 is the schematic diagram of the enrichment and desorption device used for organic matter in the volatile range of C8-C40 in the atmospheric particle phase;

Fig. 2 is the schematic diagram of the enrichment and desorption device used for organic matter in the volatile range of C8-C40 in the atmospheric particle phase;

Fig. 3 is a schematic diagram of the high and low temperature components in the enrichment and desorption equipment of organic matter in the C8-C40 volatile range in the atmospheric particle phase;

Fig. 4 is the schematic diagram of enrichment and desorption equipment for organic matter in the C8-C40 volatile range in the atmospheric particle phase;

Fig. 5 is the result graph of the chemical composition and signal value of particulate organic matter collected by the particulate organic matter online enrichment monitoring device system described in the present application;

Reference signs:

19: cutting head, 20: erosion device, 21: first electric three-way valve, 22: particle enrichment and desorption device, 23: second electric three-way valve, 24: adsorption focusing trap device or high and low temperature components, 25: The third electric three-way valve, 26: electric ball valve, 27: electronic pressure controller, 28: GCMS, 29: mass flow controller, 30; air pump, 31; air supply and air circuit pressure control system, 32: computer interactive control System; 1: Aluminum protective shell, 2: Insulation cotton, 3: Copper block, 4: Cooling sheet, 5: Resistance wire, 6: Adsorption tube, 7: Glass fiber cotton, 8: Thick-walled quartz tube, 9: Connection Screw, 10: low temperature sensor, 11: finger platform cylinder, 12: stainless steel connecting column, 13: support rod, 14: heat insulation pad, 15: insulating sleeve, 16: adsorbent, 17: temperature sensor, 18: stainless steel Screw; 33: Quartz glass tube, 34: Thin-walled quartz lining, 35: Quartz fiber filter membrane, 36: SMD heating membrane, 37: Quartz support structure, 38: Desorption quartz tube, 39: SMD Temperature sensor, 40: quartz transmission tube, 41: O ring, 42: inorganic glue sealant, 43: stainless steel screw.

detailed description

At present, the online collection devices for particulate organic matter at home and abroad generally use 316 stainless steel as the carrier medium of the filter membrane. Since the particulate organic matter is very easy to adhere to the stainless steel surface, the on-line collection device must be pre-passivated inside in practical applications. . However, the current domestic passivation treatment technology is still immature. Generally, the enrichment and desorption module needs to be taken to the American Restek company for passivation of the inner wall. This operation will undoubtedly increase the equipment cost and equipment production time. Based on this shortcoming, the applicant independently developed a particle enrichment and desorption device based on quartz material as the support carrier of the filter membrane. In this device, the "sandwich" structure of filter membrane-heating membrane-support structure is integrated, such as the "sandwich" structure of quartz fiber filter membrane-patch type heating membrane-quartz support structure, which is nested in the quartz In the pipeline, an integrated device that can collect and desorb atmospheric particulate matter is formed. The support made of quartz does not need internal passivation pretreatment. Different from the external heating rod in the existing heating device and the structural design that the temperature sensor is separated from the sampling filter membrane by a certain distance, the patch heating membrane used in this application directly heats the quartz filter membrane by contact, and attaches it to the filter membrane. The chip temperature sensor is placed between the heating diaphragm and the quartz filter membrane. This design can not only realize the rapid heating and thermal analysis of the filter membrane, but also read the real temperature at the quartz filter membrane in real time to ensure the concentration of organic matter in the quartz filter membrane. Rapid temperature rise and high-efficiency analysis avoid insufficient thermal desorption of C35-C40 high-carbon organic compounds.

At present, the pre-treatment device for particulate organic matter generally sends the collected organic matter to the GC column head for enrichment after thermal desorption. Higher and limited flow rates that the chromatographic column and mass spectrometer can withstand limit the flow rate of thermal desorption, resulting in incomplete thermal desorption of low volatile organic compounds. In order to expand the collection and measurement of particulate low-carbon organic matter, this application designs a small-scale focusing module with simple structure and easy operation at low temperature and adsorbent double enrichment after membrane sampling. The low-temperature enrichment of the adsorbent can also capture the high-carbon organic matter again through simple low-temperature control, so as to ensure that it can enter the GCMS module without loss and reduce the tailing phenomenon of the material peak. The focusing module uses a pneumatic control method to quickly switch the low-temperature enrichment and high-temperature analysis of organic matter, which avoids the temperature ambiguity of high-low temperature conversion, and can meet the temperature switching requirements of -40°C low-temperature enrichment to 320°C high-temperature desorption. The focusing module is small in size and compact in structure, which not only expands the monitoring range of the system, but also avoids peak tailing of subsequent sample peaks by the instantaneous desorption temperature rise.

Organic matter within the volatile range of C8-C40 in the atmospheric particle phase (referred to as particle phase organic matter) refers to the organic matter that exists in the form of particles in the atmosphere, and generally refers to the effective saturated vapor concentration in the range of 10 ^-1 ~ 10 ⁶ μg·m ^-3 A large class of substances whose saturated vapor pressure corresponds to saturated alkanes in the C8-C40 range.

In addition, in existing devices, electric four-way valves or six-way valves are generally used to switch the gas path, which is reasonable in principle. The valve core is prone to wear and cause air leakage in the system, and a valve core needs to be replaced basically every month. In response to this phenomenon, this application uses a commercial electric three-way ball valve based on pulse control as a component for gas circuit switching, which can reduce maintenance and costs during later instrument use to a certain extent.

As shown in Figure 1, the application provides a kind of enrichment desorption device for organic matter in the volatile range of C8-C40 in the atmospheric particle phase, comprising: pipe body 33, desorption pipe 38 and transfer pipe 40; pipe body 33, the two sides of the tube body are the sample inlet and the gas outlet respectively; in the direction of the sample injection of the organic matter, a filter membrane 35, a heating membrane 36 and a support structure 35 are sequentially arranged inside the tube body; the desorption tube 38, one side of which is welded to the side surface of the pipe body 33, and the other side extends radially outward along the pipe body 33; the transmission pipe 40, the transmission pipe 40 is L-shaped, and one side of the transmission pipe 40 The tube is welded to the support structure 35, wherein one edge of the L-shaped transfer tube extends along the inner wall of the tube body 33, and the other side of the L-shaped tube extends from the side surface of the tube body 33 opposite to the side surface where the desorption tube 38 is welded. The side surface protrudes; the support structure 35 , the desorption tube 38 and the transfer tube 40 are arranged at different positions of the tube body 33 in the direction of the sampling of the organic matter. This design ensures that the filter membrane is only heated locally, so that the temperature of the inlet and outlet is not higher than 50°C. When sealing the inlet and outlet, only ordinary O-rings are used for sealing. Cost savings.

In one embodiment of the present application, the tube body 33 is a quartz glass tube body, the desorption tube 38 is a quartz desorption tube, the transmission tube 40 is a quartz transmission tube, the filter membrane 35 is a quartz fiber filter membrane, and the heating membrane 36 is a SMD heating membrane, the support structure 35 is a quartz support net. The device is based on the quartz material as the main frame and the "sandwich" structure composed of quartz fiber filter membrane-patch heating membrane-quartz support net as a particulate organic matter collection and desorption device. The device is made of quartz and only needs a simple Wall surface cleaning (alcohol or distilled water ultrasonic, high-temperature baking is enough), does not need to be sent abroad for surface passivation treatment, which reduces the preparation time and cost of the instrument to a certain extent. In addition, the developed quartz fiber filter membrane-patch heating membrane-quartz support net "sandwich" structure can realize direct heating of the filter membrane and precise control and reading of real-time temperature, ensuring high carbon of C8-C40 Rapid thermal desorption temperature requirements and high desorption efficiency of substances.

As shown in FIG. 1 , the enrichment-desorption device further includes an inner liner 34 , which is arranged inside the tube body and between the sample inlet and the filter membrane 35 . A liner 34 is placed between the quartz fiber filter membrane 35 and the inlet of the quartz glass tube to protect the filter membrane 35 from moving due to gas flow. The inner liner 34 can be a thin-walled quartz inner liner, and its size is adapted to the thin-walled quartz glass tube body 33 .

As shown in Figure 1, the enrichment and desorption device also includes a patch temperature sensor 39, the patch temperature sensor is located in the middle of the filter membrane and the heating membrane, and there is a transfer tube near the tube body. side; preferably, the wires connected to the heating membrane and the wires connected to the patch temperature sensor are located in the transmission tube. In order to monitor the temperature of the sampling quartz fiber filter membrane in real time, the patch temperature sensor 39 is set between the quartz fiber filter membrane 35 and the patch type heating membrane 36, and is close to the side of the tube body with the transmission tube, so that the sampling filter can be accurately obtained. The real temperature at the membrane ensures that the quartz fiber filter membrane 35 can reach the accurate thermal desorption temperature in the thermal desorption stage, thereby ensuring the efficient desorption efficiency of high carbon substances. The circuit connection wires of the patch heating diaphragm 36 and the patch temperature sensor 39 are wrapped with a layer of high-temperature-resistant quartz glass fiber protective sheath to prevent the circuit connection wires from affecting the sampling airflow and thermal desorption airflow during actual high-temperature operation. Or unnecessary interference caused by subsequent detection.

As shown in FIG. 1 , in the direction of the sampling of the organic matter, the support mechanism is arranged upstream of the desorption pipe, and the transfer pipe is arranged downstream of the desorption pipe.

As shown in Figure 1, the ratio of the distance between the support structure and the desorption tube to the total length of the tube body is (0.3-1): 6, at this time, the distance between the support structure and the desorption tube The distance refers to the distance between the two in the direction parallel to the pipe body. Wherein, the ratio of the distance between the support structure and the desorption tube to the total length of the tube body is (0.3-1): 6, so that the support structure keeps a certain distance from the inlet of the tube body to avoid the filter membrane When heating, the temperature at the inlet end of the tube body is too high, resulting in poor sealing; the distance between the support structure and the desorption tube is small, and the gas transmission process of the desorbed substances is minimized.

As shown in Figure 1, the ratio of the distance between the support structure and the transmission pipe to the total length of the pipe body is (1-3): 6; at this time, the distance between the support structure and the transmission pipe is Refers to the distance between the two in the direction of the parallel pipe body. The ratio of the distance between the support structure and the transfer tube to the total length of the tube is (1-3): 6. This structure can ensure that the transfer tube desorbs the substances enriched on the filter membrane at the support structure during the high temperature analysis stage. No effect.

As shown in Figure 1, the ratio of the distance between the transfer tube and the injection port to the total length of the tube body is (3-4):6; at this time, the distance between the transfer tube and the injection port The distance refers to the distance between the two in the direction of the parallel pipe body, which can ensure that the transmission pipe does not affect the sampling airflow during the sampling stage.

As shown in Figure 1, the ratio of the distance between the desorption tube and the injection port to the total length of the tube body is (1.5-3.5): 6; The distance refers to the distance between the two in the direction of the parallel tube body. This design simplifies the sampling and desorption gas path.

As shown in Figure 2, on the sampling direction of the organic matter, the desorption pipe is arranged upstream of the support mechanism, and the transfer pipe is arranged downstream of the support mechanism; preferably, the support structure The ratio of the distance between the desorption tube and the total length of the tube body is (0.3-1): 6; further preferably, the distance between the support structure and the transfer tube is the same as that of the tube body The ratio of the total length is (1-3):6; more preferably, the ratio of the distance between the transfer tube and the injection port to the total length of the tube body is (3-4):6, more preferably Preferably, the ratio of the distance between the desorption tube and the injection port to the total length of the tube body is (0.5-2.5):6, and the rest are the same as the structure shown in Figure 1 .

As shown in Figure 1, both sides of the pipe body are sealed with a first O-ring or a polytetrafluoroethylene ferrule joint. Preferably, the material of the first O-ring is fluororubber or nitrile rubber; the desorption tube uses the first O-ring Two O-rings are used for sealing. Preferably, the material of the second O-ring is high temperature resistant polyimide; the transmission tube is sealed with a sealant. Preferably, the material of the sealant is inorganic ceramic material. The first O-ring of fluororubber, nitrile rubber or PTFE ferrule joint can withstand 150 ℃, and it is relatively easy to buy in the market. The second O-ring made of high-temperature-resistant polyimide needs to withstand 350°C, which can only be obtained through imported purchases (Agilent).

In some embodiments of the present application, the enrichment-desorption device further includes a refrigeration unit arranged outside the tube body; preferably, the refrigeration unit is a fan. The fan can cool the quartz filter membrane. The fan is placed outside the quartz main tube corresponding to the quartz filter membrane. When cooling is required, the fan works to cool the quartz filter membrane.

In the embodiment of the present application, the size of the pipe body can be selected according to the actual situation.

As shown in Figure 1, in the sampling direction of the organic matter, the support mechanism is arranged upstream of the desorption pipe, and the transfer pipe is arranged downstream of the desorption pipe; 0.3cm downstream. The enrichment and desorption device is mainly made of quartz material that does not need to be passivated inside. The enrichment and desorption device body 33 has a diameter of 1/2 inch and a length of 6 cm. Its material is a quartz glass tube. 33 is welded with a quartz support structure 37 at 2 cm from the upstream sample inlet to support and protect the sampling quartz filter membrane. Sheet-type heating membrane 36, the heating membrane 36 is equipped with a heating wire with a certain resistance value inside, the heating voltage is 24V, and the heating power is 80W. The heating membrane can realize the rapid temperature rise from 30°C to 320°C; Select the high-purity quartz filter membrane 35 with high particle retention rate, low background value and high temperature resistance as the actual sampling part of the particulate matter. The size of the quartz fiber filter membrane 35 is 1/2 inch, and it is close to the patch heating The membrane 36 is placed, and a filter membrane with a larger size can provide sufficient particle sampling surface area. In actual operation, tweezers can be used to replace the quartz filter membrane 35 . In addition, in order to avoid the long-term thermal desorption air flow causing the filter membrane position to move during the thermal desorption stage, a 3/8-inch thin-walled quartz lining is placed between the quartz fiber filter membrane 35 and the sampling port of the quartz glass tube body 33 34, used to protect the filter membrane from moving due to airflow transmission. In order to monitor the temperature at the sampling filter membrane in real time, the patch temperature sensor 39 is placed between the quartz fiber filter membrane 35 and the patch heating membrane 36 and close to the side of the quartz transmission tube 40, which can accurately monitor the temperature at the sampling filter membrane. The real temperature ensures that the quartz fiber filter membrane 35 can reach an accurate thermal desorption temperature of 320°C during the thermal desorption stage, ensuring the desorption efficiency of C35-C40 high-carbon organic matter. The outside of the patch heating diaphragm 36 and the circuit connecting wire of the patch temperature sensor 39 is wrapped with a layer of high temperature resistant quartz glass fiber protective cover. For unnecessary interference caused by air flow or follow-up detection, a quartz transfer tube 40 with a diameter of 3 mm is welded under the quartz support structure 37, and is exported from a hole 4 cm below the quartz glass tube body 33, and the length of the export is 2 cm. The quartz transmission tube 40 can be used to place the circuit connecting wire of the patch heating diaphragm 36 and the patch temperature sensor 39, and the tail end of the quartz transmission tube 40 is sealed with a sealant 42 to prevent air leakage. In practical applications, when the quartz fiber filter membrane 35 is at a high temperature thermal desorption temperature of 320°C, the temperature of the sealant 42 is actually only 40°C.

As shown in Figure 2, on the sampling direction of the organic matter, the desorption pipe is arranged upstream of the support mechanism, and the transfer pipe is arranged downstream of the support mechanism; the desorption pipe is arranged upstream of the support structure 0.3cm. The pipe body 33 of the enrichment and desorption device has a diameter of 1/2 inch and a length of 6 cm, and its material is a quartz glass tube. A quartz support structure 37 is welded at 2 cm upstream of the inlet of the quartz glass pipe body 33, above the quartz support structure 37. Place a patch-type heating film 36 corresponding to the size of the 1/2-inch quartz glass tube 33. A heating wire with a certain resistance value is arranged inside the heating film 36. The heating voltage is 24V and the heating power is 80W. The heating diaphragm can realize the rapid temperature rise from 30°C to 320°C; a quartz transfer tube 40 with a diameter of 3mm is welded under the quartz support structure 37, and is led out from a hole 4cm below the quartz glass tube body 33, and the length of the lead out 2cm, the 3mm quartz transmission tube 40 can be used to place the circuit connection line of the patch heating diaphragm 36 and the patch temperature sensor 39, and the tail end of the quartz transmission tube 40 is sealed with a sealant 42 to prevent air leakage. The rest of the structure is the same as that described in Figure 1.

In order to bring the material after thermal desorption into subsequent parts, a 1/16 inch hole is opened next to the lower end of the quartz support structure 37, and a 1/16 inch desorption quartz tube 38 is welded. The quartz tube 38 is used to transfer the thermally desorbed substance to the subsequent passivated three-way ball valve, and the two are sealed by a commercial high-temperature-resistant polyimide material O-ring 41 . In addition, in order to ensure the sealing effect between the upper end and the lower end of the quartz glass tube body 33 and the stainless steel material, commercial O-rings and subsequent electric three-way valves are also used for sealing.

In one embodiment of the present application, the main function of the particle enrichment and desorption device is to use the quartz fiber filter membrane 35 to sample and intercept the particle phase organic matter at 30°C, and then rapidly raise the temperature to 320°C to deposit on the quartz fiber The organic matters on the filter membrane 35 are desorbed at high temperature. Therefore, real-time accurate reading and high and low temperature temperature control of the quartz fiber filter membrane 35 are very important. In this application, a vortex fan with a large air volume is installed outside the tube body, aiming at the quartz fiber filter membrane 35 for rapid cooling. Since the volume of the quartz fiber filter membrane 35 is small, and the quartz glass tube body 33 is a thin-walled tube, it can be rapidly cooled. Cool down. The high temperature of the quartz fiber filter membrane 35 is achieved by using the patch heating membrane 36 with a heating power of 80W close to the quartz fiber filter membrane 35. Since the heating power is relatively large, and the heating components are relatively small and concentrated, it is possible to realize the Rapid heating of the sheet heating membrane 36. The temperature reading of the device is realized by using the patch temperature sensor 39 placed between the quartz fiber filter membrane 35 and the patch heating membrane 36. Because its position is close to the quartz fiber filter membrane 35, it can be accurately obtained. The real-time temperature at the quartz fiber filter membrane 35 places. The temperature control of the device is realized by PID algorithm adjustment by Siemens programmable logic controller (PLC).

The present application also provides an enrichment and desorption device for organic matter within the volatile range of C8-C40 in the atmospheric particle phase, including the above enrichment and desorption device and high and low temperature components.

As shown in FIG. 3 , the high and low temperature components include a high temperature module, a low temperature module and a high and low temperature switching module.

As shown in Figure 3, the high temperature module includes an adsorption tube 6 and a resistance wire 5 wound outside the adsorption tube, and the inside of the adsorption tube 6 is filled with Tenax series adsorbents; between the adsorption tube and the resistance wire There is also a layer of insulating sleeve 53 wrapped around the periphery of the adsorption tube 6 .

The high temperature module also includes a protection unit 15, which is wrapped around the periphery of the resistance wire 5; the high temperature module also includes a temperature sensor 42, and the temperature sensor 42 is arranged outside the adsorption tube body 6 and located at between the insulating sleeve 53 and the adsorption tube 6 .

As shown in Figure 3, the body of the adsorption tube is made of 316 stainless steel or German Schott-Duran high-precision quartz glass. The gas flow rate range can be controlled within 0.05-2L/min if the body of the adsorption tube is selected.

As shown in Figure 3, a thick-walled quartz tube 8 is provided near the gas outlet of the strong adsorbent, and the thick-walled quartz tube 8 is used to protect the adsorbent to avoid loss of the adsorbent caused by long-term sampling.

As shown in Figure 3, the adsorption tube also includes a heating unit 5, which is a resistance wire wound outside the adsorption tube body, and the resistance wire is wound around the outer wall of the adsorption tube body; preferably, the The resistance wire is nickel-chromium resistance wire, and the resistance wire can heat the adsorption tube body to 50-350° C. to provide a high temperature for desorption.

As shown in Figure 3, a layer of insulating sleeve 53 is also included between the adsorption tube and the heating unit 5, and the insulating sleeve 53 is wrapped around the periphery of the adsorption tube body; preferably, the protective sleeve The material of the tube is selected from one or more of alkali-free glass fiber, quartz fiber, and high silica. The insulating sleeve is used to avoid the short circuit between the resistance wire and the stainless steel adsorption tube caused by the aging of the resistance wire due to long-term use. .

As shown in FIG. 3 , the adsorption tube also includes a protection unit 15 wrapped around the heating unit; preferably, the protection unit is made of glass fiber cotton. The protection unit 15 is used as a protective sleeve wrapped around the resistance wire 5 to prevent the resistance wire 5 from being worn out due to the collision and clamping action between the resistance wire 5 and the cooling metal block, and is used to protect the heating unit 5 .

As shown in Figure 3, the adsorption tube 6 also includes a temperature sensor 17, the temperature sensor 17 is arranged outside the adsorption tube body, and is located between the insulating sleeve and the adsorption tube body 6, for displaying the temperature of the adsorbent, The temperature sensor 17 is close to the outer wall of the adsorption tube, which can display the real-time temperature of the adsorbent in a more realistic manner, so as to reduce the insufficient analysis of organic matter enrichment caused by temperature discrimination. The external PID control system is used to control the temperature of the adsorbent at + 0.1°C to ensure The temperature accuracy of the adsorbent itself.

As shown in Figure 3, the low-temperature module includes a refrigerating sheet and a metal block; the metal block is composed of two sub-metal blocks with a semicircular groove in the center and a symmetrical structure to each other, and the adsorption tube can be attached to the In the groove formed by the two sub metal blocks. Wherein, the high temperature module also includes a protection unit 15; the low temperature module also includes refrigeration plastic screws, a temperature sensor and a heat dissipation unit.

The low temperature module in the high and low temperature components includes two low temperature temperature modules and a high and low temperature switching module. The two low temperature temperature modules are arranged symmetrically opposite each other, and are connected and fixed to the finger platform cylinder 11 through a stainless steel connecting column 12, which is The adsorption tube provides constant enrichment at low temperature; the pneumatic drive device is connected to the two low-temperature temperature modules, and the pneumatic drive device can drive the two low-temperature temperature modules to move toward each other or oppositely along the longitudinal direction, when the two low-temperature temperature modules face each other Capable of tightly clamping the sorbent tube when moving and contacting the setting, and releasing the sorbent tube when the two cryogenic temperature modules move in opposite directions and separate the setting.

The low-temperature temperature module includes a cooling plate 4, a metal block 3, plastic screws, a temperature sensor, and a heat dissipation unit; the cooling plate is a three-stage semiconductor refrigeration element that can reduce the temperature of the adsorption tube to -40°C, and can continuously provide low temperature. The metal block selects the metal block 3 with lower specific heat capacity as the heat conduction medium. For example, the metal block 3 is a copper block, and the metal block is composed of two symmetrical sub-metal blocks that are provided with a semicircular groove at the center and can be opened and closed. The tube can be fitly arranged in the groove formed by the two sub-metal blocks, and the two sub-metal blocks are arranged symmetrically opposite to each other to form the cryogenic temperature module.

The cold end of the cooling sheet 4 is closely attached to the metal block 3, and the metal block 3 is closely arranged with the cold end of the cooling sheet through a thermally conductive silicone grease layer, and the hot end of the cooling sheet 4 can dissipate heat through another thermally conductive silicone grease layer and a copper tube The radiator and the cooling fan are connected and arranged; the copper tube radiator is used for the heat dissipation of the cooling sheet, and the heat is output to the cooling fan by utilizing the excellent thermal conductivity of the copper tube and the condensation conversion of the liquid in the copper tube. One side of the copper tube radiator is connected to the hot end of the cooling plate 4 through a heat-conducting silicone grease layer; the other side is connected to the heat dissipation fan through its own button screw. On the outer layer of the metal block 3, a thin-walled aluminum protective shell is placed, and heat insulation cotton is closely arranged between the metal block 3 and the aluminum protective shell, and the metal block is connected with the aluminum protective shell by plastic screws.

In a specific embodiment of the present application, as shown in Figure 2, the low temperature module is composed of two sub-low temperature modules that are symmetrical to each other, and the sub-modules are controlled by a pneumatic drive device to separate or close to realize the high and low temperature of the adsorption tube. Quick toggle function. The sub-temperature module uses a copper block 3 with a lower specific heat capacity as the heat conduction medium. The size of the copper block 3 is 130mm*30mm. A semicircular groove corresponding to the outer diameter of the adsorption tube is opened in the center of the copper block 3. The adsorption tube 6 is placed in this In the circular groove, the adsorption tube can be seamlessly wrapped when the sub-temperature module is closed, so as to realize the temperature transfer. In order to reduce the temperature loss of the copper block 3, an aluminum protective shell 1 is added outside it. The size of the aluminum protective shell 1 is 140*33mm. The aluminum protective shell 1 and the copper block 3 use M4*12 PTFE screws 9 Connect and fill the gap between the two with thermal insulation cotton 2 to reduce the temperature of the sub-temperature modules and the transmission loss of air. At the same time, a support rod 13 is used to fix and connect the adsorption tube 6. The lower end of the support rod is connected to the workbench through an insulating pad 14 to reduce the temperature transmission loss. The upper end of the support rod 13 is passed through M4*16 stainless steel screws 43 It is connected with the adsorption tube 6, so as to support and fix the adsorption tube 6. The temperature sensor 10 of the low-temperature module is placed at the side opening of the copper block 3, that is, the copper block 3 and the side of the aluminum protective case 1 are opened, and its size is adapted to the outer diameter (4mm) of the low-temperature temperature sensor 10. The temperature sensor 10 is placed inside the aluminum block 3 to display the real temperature of the aluminum block 3 in real time. Generally, the temperature at the low temperature module is controlled to keep -40°C.

The high-temperature module of this application, that is, the heating unit of the adsorption tube is mainly heated by the DC voltage of the resistance wire 5, and the resistance wire is evenly and tightly wound on the outer wall of the adsorption tube, so as to avoid clamping and adsorption of the low-temperature temperature module during low-temperature transfer. If the tube causes the leakage and short circuit of the resistance wire due to mechanical impact, the outer wall of the adsorption tube wrapped with the resistance wire is wrapped with a layer of insulating protective sleeve. The material of the protective sleeve is glass fiber cotton, which can prevent the short circuit of the resistance wire. It will not interfere with low-temperature transmission, and the heating temperature can be raised from -40°C to 320°C within 4s; the resistance wire is only heated when the adsorption tube needs high temperature, and is not heated for the rest of the time.

The low-temperature module of this application, that is, the cooling is realized by the three-stage semiconductor refrigeration element 4 at a low temperature of -40°C. Since the temperature module is small in size, the temperature control module can be kept at a constant low temperature of -40°C by using three-stage refrigeration chips. The cold end of the cooling plate 4 is installed on the copper block 3 on the opposite side of the semicircular groove end, and the two are closely connected by heat-conducting silicone grease, and the hot end of the cooling plate 4 can be connected to the copper tube radiator Connected to ensure the efficient work of the cooling plate. The refrigerating sheet is always in the cooling working state after starting up, and the temperature sensor 10 displays the low temperature in real time, that is to ensure that the sub-temperature module is always at a constant temperature of -40°C, so as to quickly transfer the low temperature to the adsorption tube at any time.

The high-low temperature switching module includes a pneumatic drive device, which controls the opening or closing of the low-temperature sub-metal block by controlling whether the carrier gas is introduced or not, and finally realizes the high-temperature mode and low-temperature mode of the adsorption tube. switch between

When the carrier gas is fed into the pneumatic drive device, the two symmetrical sub-metal blocks move apart longitudinally relative to each other. There is a gap between the tubes, and the heating module is controlled to work, and the adsorption tube is in high temperature mode; when the pneumatic device has no carrier gas, the two symmetrical sub-metal blocks move toward each other in the longitudinal direction. At this time, the two symmetrical The sub-metal blocks are closed, so that the two symmetrical sub-metals clamp the adsorption tube, the heating module is controlled to stop working, and the adsorption tube is in a low-temperature mode.

The switch between high temperature mode and low temperature mode is mainly to make the adsorption tube in high temperature and low temperature state by controlling the pneumatic drive device, as follows:

As shown in Figure 3, the pneumatic device includes a miniature finger platform cylinder, two-position five-way valve, PU pneumatic high-pressure pipe and high-pressure air source, and the miniature finger platform cylinder is connected to the bottom of the two sub-metal blocks through a stainless steel connecting column connection, the air inlet and outlet of the micro-finger platform cylinder are respectively connected to the working port of a two-position five-way valve, the air inlet of the two-position five-way valve is connected to a high-pressure air source, and the two-position five-way The two exhaust ports of the valve are connected to the muffler. The miniature finger platform cylinder can drive the two half-metal blocks to move toward each other or oppositely along the longitudinal direction through the drive of the two-position five-way valve and the high-pressure air source, thereby controlling the overall temperature of the module. The opening or closing of the adsorption tube to realize the conversion from low temperature to high temperature;

The axial opening and closing movement of the micro-finger platform cylinder 11 is controlled by the pneumatic drive device to realize the switching between high and low temperature of the adsorption tube. To open, drive the two sub-metal blocks to separate, thereby releasing the adsorption tube 6, that is, there is a gap between the adsorption tube 6 and the two metal blocks at this time, and the resistance wire wrapped around the outer wall of the adsorption tube 6 is controlled to work. , heat the adsorption tube to the required high temperature, and the adsorption tube 6 is in the high-temperature mode; when the adsorption tube 6 needs to work at a low temperature, control the resistance wire to stop heating, and the pneumatic device controls the axial closure of the micro-finger platform cylinder 11, thereby driving The two sub-metal blocks are closed and clamp the adsorption tube, the low temperature of the two sub-metal blocks is transferred to the adsorption tube, so as to realize the conversion of low temperature, and the adsorption tube 6 is in the low temperature mode.

At present, the particulate organic matter measurement device generally sends the collected organic matter to the GC column for enrichment after thermal desorption. The single temperature enrichment can easily lead to the penetration loss of C8-C14 organic matter, and because the chromatographic column The high gas resistance and the limited flow rate that the chromatographic column and mass spectrometer can withstand limit the thermal desorption flow rate, resulting in incomplete thermal desorption of low volatile organic compounds. In order to expand the measurement of particulate low-carbon organic matter, this application designed a small focusing module with simple structure and easy operation, low temperature and double enrichment of adsorbent after sampling the filter membrane. Enrichment, high-carbon organic matter can also be re-captured at low temperature to ensure that it can enter the GCMS module without loss and reduce the tailing phenomenon of material peaks. The focusing module adopts a pneumatic control method, which can quickly switch between low-temperature enrichment and high-temperature analysis of organic matter, avoiding the temperature ambiguity of high-low temperature conversion, and can meet the temperature switching requirements of -40°C low-temperature enrichment to 320°C high-temperature desorption . The focusing module is small in size and compact in structure, which not only expands the monitoring range of the system, but also avoids peak tailing of subsequent sample peaks by the instantaneous desorption temperature rise.

The present application provides a method for using the above-mentioned enrichment-desorption device or the above-mentioned enrichment-desorption device in the on-line measurement of organic compounds within the volatile range of C8-C40 in the atmospheric particle phase.

As shown in Figure 4, this application provides an online measurement method for organic compounds within the volatile range of C8-C40 in the atmospheric particle phase, including sampling mode, purging mode, focus enrichment mode, sampling mode, aging mode and cooling standby The model provides data support for the source and precise traceability of atmospheric particulate matter.

Specifically include the following steps:

Sampling steps: the computer interactive control system 32 controls the particle enrichment and desorption device 22 (that is, the enrichment and desorption device for organic matter in the C8-C40 volatile range in the atmospheric particle phase) to be in the 30 ° C collection state, and the air pump 30 pumps The atmospheric sample passes through the cutting head 19, the dissolution device 20, the first electric three-way valve 21, the particle enrichment and desorption device 22, the second electric three-way valve 23, the first mass flow controller 29, and then passes through the air pump 30 discharge, so that the organic matter in the atmospheric particulate matter is trapped at the quartz fiber filter membrane 35 in the particulate matter enrichment and desorption device 22 . At this stage, the adsorption focusing trap device 24 (i.e. high and low temperature components) is in the state of -20°C low temperature to be enriched, and another carrier gas comes out from the gas supply and gas path pressure control system 31 and passes through the third electric three-way valve 25, electric ball valve 26. Particulate matter enrichment and desorption device 22, mass flow controller 29, and air pump 30 are then discharged, thereby protecting the electric ball valve 26 at high temperature and the internal coating of the high-temperature pipeline therein; at this time, the protective carrier gas of GCMS 28 After coming out of the gas supply and gas circuit pressure control system 31, it enters the GCMS 28 through the electronic pressure controller 27;

Purging step: keep the particle enrichment and desorption device 22 at a low temperature of 30°C. In this mode, the carrier gas passes through the gas supply and pressure control system 31 and the first electric three-way valve 21, and the particle enrichment and desorption device The quartz fiber filter membrane 35 in 22 and subsequent pipeline components are purged with carrier gas to remove excess interfering gases such as residual oxygen adsorbed in the quartz fiber filter membrane 35 . At this stage, the adsorption focusing trap device 24 is still in the state of -20°C low temperature waiting to be enriched (the carrier gas input to the micro-finger platform cylinder 11 is stopped, and the two low-temperature sub-temperature modules of the adsorption focusing trap device 24 are closed, so that the adsorption tube body 6 is at -20°C low temperature state), another carrier gas comes out from the gas supply and gas path pressure control system 31 and then passes through the third electric three-way valve 25, electric ball valve 26, particle enrichment and desorption device 22, mass flow controller 29, The air pump 30 is then discharged to protect the electric ball valve 26 at high temperature and the inner coating of the high-temperature pipeline; at this time, the protective carrier gas of GCMS 28 comes out of the gas supply and gas path pressure control system 31 and is controlled by electronic pressure. device 27 into GCMS 28;

Focusing enrichment step: in focusing mode, the computer interactive control system 32 controls the heating wire in the particle enrichment and desorption device 22 to immediately heat up, and the temperature of the quartz fiber filter membrane 35 can be raised from 30°C to 320°C within 4s; keep the adsorption The focus well 6 in the focus well device 24 is still in the low-temperature enrichment state at -20°C (that is, the carrier gas input to the micro-finger platform cylinder 11 is stopped, and the two low-temperature sub-temperature modules of the adsorption focus well device 24 are closed, so that the focus well 6 in a low temperature state of -20°C). In this mode, after the carrier gas passes through the gas supply and pressure control system 31 and the first electric three-way valve 21, the material desorbed from the quartz fiber filter membrane in the particulate matter enrichment and desorption device 22 is purged up. After the other carrier gas passes through the gas supply and pressure control system 31 and the second electric three-way valve 23, the material desorbed from the quartz fiber filter membrane in the particle enrichment and desorption device 22 is purged downward, and the upper and lower pinching will blow The swept out substances pass through the BA port of the three-way ball valve 26 and are brought to the adsorbent in the focusing trap 6 in the adsorption focusing trap device 24 at -20°C. The air pipe part of the air is captured, and the volatile low-carbon organic matter is captured by the adsorbent at a low temperature, and the excess unadsorbed impurities are discharged into the ambient atmosphere through the third electric three-way valve 25; at this time, The protective carrier gas of GCMS28 comes out from the gas supply and gas path pressure control system 31 and enters the GCMS 28 through the electronic pressure controller 27;

Measurement steps: After the adsorption and enrichment of organic matter is completed, the computer interactive control system 32 controls the adsorption tube body 6 in the adsorption focusing trap device 24 to rapidly raise the temperature from a low temperature of -20°C to a high temperature of desorption at 320°C (that is, by using the gas supply and pressure control system The carrier gas from 31 drives the micro-finger platform cylinder 11 to open, drives the two low-temperature modules to open, and controls the heating wire wrapped around the adsorption tube 6 to work quickly through the computer interactive control system 32), and the carrier gas passes through the gas supply and pressure control system 31 and the third electric three-way valve 25, the organic matter to be measured, which is enriched in the adsorption tube body 6 in the adsorption focusing trap device 24 and released at high temperature, is brought into the GCMS 28 through the AC port of the electric three-way ball valve 26 for analysis Measurement, at this time, the electronic pressure controller 27 is closed, and no gas path output is performed;

Aging step: After the sample injection is completed, in order to remove the residual impurities in the system pipeline, the computer interactive control system 32 controls the electric three-way ball valve AB to connect, and after it comes out of the air supply and air pressure control system 31, it passes through the electronic pressure controller. 27 to the GCMS 28, to provide the GCMS 28 with the corresponding carrier gas for separation and measurement; at the same time, control the particle enrichment and desorption device 22 (i.e. the enrichment desorption device) and the adsorption focusing trap device 24 (i.e. the high and low temperature components) to be at 330°C High temperature state. After the carrier gas comes out of the gas supply and gas path pressure control system 31, it passes through the first electric three-way valve 21, the particle enrichment and desorption device 22, the second electric three-way valve 23, the mass flow controller 29, and the air pump 30. The pipelines and parts in the particulate matter enrichment and desorption device 22 are cleaned with high-temperature carrier gas; another carrier gas comes out from the gas supply and gas path pressure control system 31 and passes through the third electric three-way valve 25 and electric ball valve 26 to enrich the particulate matter. Integrating desorption device 22, mass flow controller 29, and air pump 30, so as to realize aging cleaning of pipelines and components in adsorption focusing trap device 24;

Cooling standby step: After the aging cleaning is completed, the computer interactive control system 34 controls the particle enrichment and desorption device 22 and the high and low temperature components 24 to be in a low-temperature waiting state for enrichment, waiting for the next particle collection process. After a carrier gas comes out of the gas supply and gas path pressure control system 31, it is discharged through the third electric three-way valve 25, electric ball valve 26, particulate matter enrichment and desorption device 22, mass flow controller 29, and air pump 30, so that the high temperature The electric ball valve 26 and the internal coating of the high-temperature pipeline are protected; at this time, the GCMS 28 is still in the stage of temperature programming and mass spectrometry detection, and its separation and detection carrier gas comes out from the gas supply and gas pressure control system 31 and passes through Electronic pressure controller 27 provides;

So far, a complete cycle of online measurement of atmospheric particulate organic matter has been completed. Time sequence control of the entire system and components is realized through the computer interactive control system 32, and the six steps can be automatically cycled.

In order to minimize the loss of viscous organic particles inside the system, all components and continuous pipelines after thermal desorption are equipped with a 300-320°C adjustable high-temperature heating device, and the internal pipeline is shortened as much as possible. The connection length minimizes the loss of high-carbon organic matter, especially C35-C40 and PAH substances with 4 or more rings in the pipeline.

The gas circuit of the whole device system is simple and easy to operate. It can directly monitor the low-concentration particulate organic matter in the volatile range of C8-C40 under atmospheric environmental conditions. The time resolution is 30-90min, and the sampling time can be adjusted freely according to the measurement needs. .

Example 1

As shown in Figure 1, in the enrichment and desorption device, the pipe body 33 has a diameter of 1/2 inch and a length of 6 cm. A quartz support structure 37 is welded at 2 cm upstream of the sample inlet, and a patch-type heating diaphragm 36 corresponding to the size of the 1/2-inch quartz glass tube 33 is placed above the quartz support structure 37, and the heating diaphragm 36 is internally deployed There is a heating wire with a certain resistance value, the heating voltage is 24V, and the heating power is 80W. The high-purity quartz filter membrane 35 is selected as the actual sampling part of the particulate matter. The size of the quartz fiber filter membrane 35 is 1/2 inch, and it is close to the patch The type heating membrane 36 is placed, and the filter membrane with a larger size can provide sufficient particle sampling surface area. A 3/8-inch thin-walled quartz lining 34 is placed between the quartz fiber filter membrane 35 and the sampling port of the quartz glass tube body 33 to protect the filter membrane from moving due to air flow. Placing the patch temperature sensor 39 between the quartz fiber filter membrane 35 and the patch heating membrane 36 and close to the side of the quartz transmission tube 40 can accurately monitor the real temperature at the sampling filter membrane. The patch heating diaphragm 36 and the circuit connecting wire of the patch temperature sensor 39 are all wrapped with a layer of high-temperature-resistant quartz glass fiber protective sleeve, and a quartz transmission tube 40 with a diameter of 3 mm is welded under the quartz support structure 37, and Lead out from the hole 4cm below the quartz glass tube body 33, and the lead-out length is 2cm. The quartz transmission tube 40 with a diameter of 3mm can be used to place the circuit connection line of the patch heating diaphragm 36 and the patch temperature sensor 39, and the quartz transmission The tail end of the pipe 40 is sealed with a sealant 42 to prevent air leakage. In practical applications, when the quartz fiber filter membrane 35 is at a high temperature thermal desorption temperature of 320°C, the temperature of the sealant 42 is actually only 40°C. Open a 1/16 inch hole next to the lower end of the quartz support structure 37, and weld a 1/16 inch desorption quartz tube 38, which is used to transport the material that is thermally desorbed to the subsequent In the passivated three-way ball valve, a commercial high-temperature-resistant polyimide O-ring 41 is used between the two to seal the gas path. In addition, in order to ensure the sealing effect between the upper end and the lower end of the quartz glass tube body 33 and the stainless steel material, commercial O-rings and subsequent electric three-way valves are also used for sealing.

Example 2

As shown in Figure 4, an enrichment and desorption device includes the enrichment and desorption device in Example 1, and also includes a high and low temperature component, including a high temperature module, a low temperature module and a high and low temperature switching module, the high temperature module It includes the adsorption tube body 6 and the insulating resistance wire tightly wound on the outer wall. The interior of the adsorption tube is filled with Tenax adsorbent. The adsorption tube body is passivated thin-walled corrosion-resistant 316 stainless steel. The size of the attached tube body is as follows: inner diameter : 2.2mm, outer diameter: 2.5mm, length: 600mm. There is also a layer of insulating sleeve 53 between the adsorption tube and the resistance wire, the insulating sleeve 53 is wrapped around the periphery of the adsorption tube body 6, and the material of the insulating sleeve is glass fiber cotton. The outer wall of the adsorption tube is tightly wound with insulating resistance wire, which is used as a heating unit to provide high temperature for analysis. A protective sleeve 15 made of glass fiber is wrapped on the outer layer of the resistance wire, and the protection sleeve 15 is used as a protection unit to protect the resistance wire; The temperature sensor 42 is placed at the position, and the temperature sensor 42 is close to the outer wall of the adsorption tube, which can display the real-time temperature of the adsorbent in a more realistic manner, so as to reduce the insufficient analysis of organic matter enrichment caused by temperature discrimination, and use an external PID control system to control the temperature of the adsorbent. At + 0.1 degrees, the temperature accuracy of the adsorbent itself is guaranteed. Among them, the resistance wire high-temperature module tightly wound on the outer wall of the adsorption tube can raise the temperature of the adsorption tube to 320°C-350°C. Low-temperature module, the low-temperature module includes a cooling plate, a metal block, plastic screws, a temperature sensor and a heat dissipation unit. The metal block is composed of two symmetrical sub-copper blocks with a semi-circular groove in the center and can be opened and closed. The adsorption tube can be fitted on the In the groove formed by the two sub-copper blocks. The cooling chip is a three-stage semiconductor cooling element, which can reduce the temperature of the adsorption tube to -40°C and can continuously provide low temperature; the size of the two sub-copper blocks is 130mm*30mm. An aluminum protective shell is added outside the copper block. The size of the aluminum protective shell is 140*33mm. The aluminum protective shell and the two half-copper blocks are connected with M4*12 PTFE screws. The gap is filled with thermal insulation cotton to reduce the temperature of the sub-temperature module and the transmission loss of air. At the same time, a support rod is used to fix and connect the adsorption tube. The lower end of the support rod is connected to the workbench through an insulating pad to reduce the temperature transmission loss. The upper end of the support rod is connected to the adsorption tube through M4*16 stainless steel screws. , so as to support and fix the adsorption tube. The temperature sensor of the low-temperature module is placed at the side opening of the copper block, that is, the copper block and the side of the aluminum protective case are opened, and its size is adapted to the outer diameter (4mm) of the low-temperature temperature sensor. Place the low-temperature temperature sensor on the copper block. the interior of the block. The high and low temperature switching module includes a pneumatic device. The pneumatic device includes a miniature finger platform cylinder, two-position five-way valve, PU pneumatic high-pressure pipe and high-pressure air source. The miniature finger platform cylinder is connected to the bottom of the two sub-metal blocks through a stainless steel connecting column. connection, the air inlet and outlet of the micro-finger platform cylinder are respectively connected to the working port of a two-position five-way valve, the air inlet of the two-position five-way valve is connected to a high-pressure air source, and the two-position five-way The two exhaust ports of the valve are connected with the muffler.

Fig. 5 is a graph showing the chemical composition and signal value of atmospheric environment particulate organic matter collected by the online enrichment monitoring device for particulate organic matter described in the present application. The abscissa is the collection time, and the ordinate is the TIC intensity signal value of the Agilent mass spectrometer. Through the measurement of this system, the molecular level information of particulate organic matter in the atmosphere can be obtained, providing basic data support for the traceability and refined control of atmospheric particulate matter.

Claims (15)

1. An enrichment and desorption device for organic matter in the C8-C40 volatile range in the atmospheric particle phase, characterized in that it comprises: a tube body, a desorption tube and a transfer tube; The tube body, the two sides of the tube body are the sample inlet and the gas outlet respectively; In the direction of the sampling of the organic matter, a filter membrane, a heating membrane and a support structure are sequentially arranged inside the tube body; A desorption tube, one side of which is welded to the side surface of the tube body, and the other side extends radially outward along the tube body; The transmission pipe is L-shaped, and one side of the transmission pipe is welded to the support structure, wherein one edge of the L-shaped transmission pipe extends along the inner wall of the pipe, and the other side of the L-shaped pipe is welded from the pipe body to the support structure. One side surface of the desorption tube is opposite to the other side surface protruding; The support structure, the desorption tube and the transfer tube are arranged at different positions of the tube body in the direction of the sampling of the organic matter. 2. enrichment desorption device according to claim 1, is characterized in that, In the sampling direction of the organic matter, the support mechanism is arranged upstream of the desorption pipe, and the transfer pipe is arranged downstream of the desorption pipe; Preferably, the ratio of the distance between the support structure and the desorption tube to the total length of the tube body is (0.3-1):6; Further preferably, the ratio of the distance between the support structure and the transmission pipe to the total length of the pipe body is (1-3):6; More preferably, the ratio of the distance between the transfer tube and the sample inlet to the total length of the tube body is (3-4):6. More preferably, the ratio of the distance between the desorption tube and the injection port to the total length of the tube body is (1.5-3.5):6. 3. The enrichment-desorption device according to claim 2, characterized in that, In the sampling direction of the organic matter, the desorption pipe is arranged upstream of the support mechanism, and the transfer pipe is arranged downstream of the support mechanism; Preferably, the ratio of the distance between the support structure and the desorption tube to the total length of the tube body is (0.3-1):6; Further preferably, the ratio of the distance between the support structure and the transmission pipe to the total length of the pipe body is (1-3):6; More preferably, the ratio of the distance between the transfer tube and the sample inlet to the total length of the tube body is (3-4):6. More preferably, the ratio of the distance between the desorption tube and the injection port to the total length of the tube body is (0.5-2.5):6. 4. enrichment desorption device according to claim 1, is characterized in that, The enrichment-desorption device also includes a liner, the liner is arranged inside the tube body and is located between the sample inlet and the filter membrane. 5. The enrichment-desorption device according to claim 1, characterized in that, The enrichment-desorption device also includes a patch temperature sensor, the patch temperature sensor is located in the middle of the filter membrane and the heating membrane, and is close to the side of the tube body with the transfer tube; Preferably, the wires connected to the heating membrane and the wires connected to the patch temperature sensor are located in the transmission tube. 6. The enrichment-desorption device according to claim 1, characterized in that, Both sides of the pipe body are sealed with a first O-ring or a polytetrafluoroethylene joint. Preferably, the first O-ring is made of fluororubber or nitrile rubber; The desorption tube is sealed with a second O-ring, preferably, the second O-ring is made of polyimide; The transmission pipe is sealed with a sealant, preferably, the material of the sealant is inorganic ceramic material. 7. The enrichment-desorption device according to claim 1, characterized in that, The filter membrane is a quartz fiber filter membrane. 8. The enrichment-desorption device according to claim 1, characterized in that, The enrichment-desorption device also includes a refrigeration unit arranged outside the tube body; Preferably, the cooling unit is a fan. 9. A device for enrichment and desorption of organic matter within the volatile range of C8-C40 in the atmospheric particle phase, characterized in that it comprises the enrichment and desorption device according to any one of claims 1-8. 10. The enrichment-desorption device according to claim 9, further comprising high and low temperature components; The high and low temperature components include a high temperature module, a low temperature module and a high and low temperature switching module. 11. The enrichment-desorption device according to claim 10, wherein, The high temperature module includes an adsorption tube and a resistance wire wound outside the adsorption tube, and the inside of the adsorption tube is filled with Tenax series adsorbents; Preferably, a layer of insulating sleeve is further included between the adsorption tube and the resistance wire, and the insulating sleeve is wrapped around the periphery of the adsorption tube; Further preferably, the high temperature module further includes a protection unit wrapped around the resistance wire; More preferably, the high temperature module further includes a temperature sensor, and the temperature sensor is arranged outside the adsorption tube body and between the insulating sleeve and the adsorption tube. 12. The enrichment-desorption device according to claim 10, wherein, The low-temperature module includes a cooling plate and a metal block. The metal block is composed of two symmetrical sub-metal blocks with a semicircular groove in the center and can be opened and closed. The adsorption tube can be attached to the two symmetrical sub-metal blocks. in the groove formed; Preferably, The cold end of the refrigerating plate is closely attached to the metal block. 13. The enrichment-desorption device according to claim 10, wherein, The high and low temperature switching module includes a pneumatic drive device, and the pneumatic drive device realizes the switch between the high temperature mode and the low temperature mode of the adsorption tube by separating and closing the low temperature sub-metal block; Preferably, When the pneumatic drive device is supplied with carrier gas, the two symmetrical sub-metal blocks move relative to each other, so that there is a gap between the two symmetrical sub-metal blocks and the adsorption tube, and the heating module is controlled to work in a high-temperature mode ; When the pneumatic device is not supplied with carrier gas, the two symmetrical sub-metal blocks move toward each other, so that the two symmetrical sub-metal blocks adhere to the adsorption tube, and the heating module is controlled to stop working, and is in a low-temperature mode. 14. A kind of enrichment desorption device described in any one of claim 1-8 or the enrichment desorption equipment described in any one of claim 9-13 is used in the C8-C40 volatility range in atmospheric particle phase A method for on-line measurement of internal particle phase organic matter. 15. The method of claim 14, comprising Sampling step, purging step, focusing enrichment step, measurement step; wherein, Sampling step: passing the sample to be detected into the enrichment desorption device, so that the particulate phase organic matter is enriched in the enrichment desorption device; Purging step: purging the enrichment-desorption device and its transmission route or the enrichment-desorption device and its transmission route with carrier gas to remove excess gas; Focusing enrichment step: desorb the particulate phase organic matter adsorbed in the enrichment desorption device and enter the enrichment desorption device; Measurement steps: desorb the organic matter in the particle phase adsorbed in the enrichment-desorption device, and separate and measure the organic matter in the particle phase.

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