Automatic monitoring system for semi-volatile organic compounds in ambient air and waste gas

Abstract

The invention discloses an automatic monitoring system for semi-volatile organic compounds in ambient air and waste gas, and belongs to the technical field of environmental monitoring. The device comprises an automatic sample injection module, a sampling efficiency investigation module, a solvent adding module, a solvent blowing module, a to-be-detected object focusing module, a gas chromatography-mass spectrometer and a waste liquid barrel, the automatic sample injection module comprises an automatic sample injection base and a sampling cavity, the automatic sample injection base comprises a waiting area, a sampling area and an extraction area, and the sampling cavity of the extraction area, the solvent blow-off module, the to-be-detected object focusing module and the gas chromatography-mass spectrometer are sequentially connected through pipelines. According to the invention, automation and high efficiency of monitoring of semi-volatile organic compounds in ambient air and waste gas are realized; meanwhile, the sample injection amount of a target object is greatly increased through the sample injection mode of the system, compared with a traditional analysis technical means, the detection limit is reduced, the sensitivity of the method is improved, more semi-volatile organic compounds can be detected, and the monitoring frequency can be increased.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental monitoring, and in particular relates to an automatic monitoring system for semi-volatile organic compounds in ambient air and waste gas. Background Art

[0002] Semi-volatile organic pollutants (SVOCs) usually refer to organic substances with boiling points between 170 and 350 ° C and low vapor pressure. Due to the vague classification basis, they often overlap with volatile organic compounds. The SVOCs that environmental monitoring focuses on now mainly include dioxins, polycyclic aromatic hydrocarbons, organic pesticides, chlorobenzenes, polychlorinated biphenyls, pyridines, quinolines, nitrobenzenes, phthalates, nitrosamines, anilines, phenols, polychlorinated naphthalenes and polybrominated diphenyl ethers, etc., which already include substances with boiling points exceeding 350 ° C. Among them, some SVOCs with high boiling points or strong polarity or high viscosity are easily adsorbed on particulate matter. Many SVOCs substances have direct hazards to the ecological environment or human health, such as dioxins, polycyclic aromatic hydrocarbons, organic pesticides and other compounds, which exist in the ambient air in gaseous state, aerosol, or attached to particulate matter. Therefore, it is necessary to monitor SVOCs in ambient air and exhaust gas.

[0003] There are two existing monitoring methods for SVOCs in the atmosphere: offline monitoring and online monitoring. Offline monitoring is done by sampling personnel on-site and transporting them to the laboratory for analysis. The entire analysis process is relatively long and requires sample collection, transportation, circulation, and analysis. Online monitoring equipment mainly monitors SVOCs in the gaseous state and is difficult to use for monitoring SVOCs with higher boiling points in particulate matter.

[0004] Existing monitoring technologies: 1. Mainstream analysis methods at home and abroad: Use filter membrane (collection of particle state) + solid phase adsorbent (enrichment of gas state), adopt rapid solvent extraction or Soxhlet extraction, extract with organic solvent, and then concentrate the extract to 0.1~1mL by nitrogen blowing. The final concentrate is then injected into the gas chromatograph for analysis through a liquid injector (the injection volume is generally 1μL, basically not more than 2μL).

[0005] For details, please refer to: HJ 646-2013 "Determination of Polycyclic Aromatic Hydrocarbons in Gas Phase and Particles of Ambient Air and Exhaust Gas by Gas Chromatography-Mass Spectrometry" and HJ 691-2014 "Technical Guidelines for Sampling Semi-volatile Organic Compounds in Ambient Air".

[0006] 2. New methods such as the US EPA: Use solid-phase adsorption materials to collect, then use high temperature to vaporize semi-volatile organic compounds, and then use inert gas to enrich them in a cold trap, and then use the cold trap for thermal desorption and gas chromatography analysis.

[0007] The disadvantages of the first monitoring technology are: (1) The degree of automation is not high. After concentration, the concentrate needs to be manually transferred to the instrument for analysis; (2) The injection volume is only 0.1%~1% of the concentrate. The injection volume is too small and the monitoring sensitivity is low, which makes it difficult to accurately analyze certain trace semi-volatile organic compounds.

[0008] Disadvantages of the second monitoring technology: it is difficult to completely vaporize and remove the collected semi-volatile organic compounds by heating, the recovery rate of some substances with high boiling points or substances with strong adsorbent binding is low, and the monitoring cost is high. Summary of the invention

[0009] The object of the present invention is to provide an automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas to solve the problems existing in the background technology.

[0010] The objective of the present invention is achieved through the following technical solutions: An automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas, comprising an automatic sampling module, a sampling efficiency investigation module, a solvent addition module, a solvent blowing module, a test object focusing module, a gas chromatograph-mass spectrometer and a waste liquid barrel; The automatic sampling module comprises an automatic sampling base and a sampling cavity, wherein the automatic sampling base comprises a waiting area, a sampling area and an extraction area, wherein a plurality of sampling cavities are respectively arranged in the waiting area, the sampling area and the extraction area, wherein a sampling cover and a sampling assembly are provided on the top of the sampling cavity in the sampling area, and an extraction cover is provided on the top of the sampling cavity in the extraction area; The sampling efficiency investigation module is connected to the sampling cover; the solvent addition module is connected to the extraction cover; The extraction cover, solvent blowing module, analyte focusing module and gas chromatography-mass spectrometer are connected in sequence through pipelines; The waste liquid barrel is connected to the solvent adding module, the solvent blowing module and the object to be tested focusing module respectively.

[0011] Furthermore, the sampling cavity and the automatic sampling base are fixed by plugging, a first temperature regulating module is provided outside the sampling area and the extraction area, a heat insulation plate is provided between the sampling area and the extraction area, the sampling cavity has an inverted cone structure, and a filter membrane pressure ring, a filter membrane, a first support member, a solid phase adsorption material and a second support member are provided in sequence from top to bottom in the sampling cavity, an outlet channel is provided on one side of the top of the sampling cavity, and the outlet channel is connected to the small end in the sampling cavity.

[0012] Furthermore, the sampling cover and the extraction cover are connected to the corresponding sampling cavity through a sealing nut, respectively. A sampling inlet and a sampling outlet are provided on the top of the sampling cover. The sampling inlet is located at the center of the sampling cover and communicates with the corresponding sampling cavity, and the sampling outlet corresponds to and communicates with the outlet channel. An extraction liquid inlet and an extraction liquid outlet are provided on the top of the extraction cover. The extraction liquid inlet is located at the center of the extraction cover and is connected to the corresponding sampling cavity. The extraction liquid outlet corresponds to and is connected to the outlet channel. An electromagnetic switch valve is provided at the extraction liquid inlet.

[0013] Furthermore, the sampling component includes an oil-free air pump, a flow controller, a first three-way switching valve and a filter. The two groups of the oil-free air pump and the flow controller are respectively connected to the first three-way switching valve, one end of the first three-way switching valve is connected to the sampling outlet, and the filter is located between the first three-way switching valve and the sampling outlet.

[0014] Furthermore, the solvent addition module includes a first inert gas input component, a first multi-position selector valve, a second multi-position selector valve and an extraction solvent bottle. The first multi-position selector valve, the second multi-position selector valve, the first inert gas input component and the extraction liquid inlet are connected through a four-way connection. The extraction solvent bottle is connected to the first multi-position selector valve and the second multi-position selector valve, respectively. The first multi-position selector valve and the second multi-position selector valve are both provided with injection pumps. The second multi-position selector valve is also provided with a first substitute solution bottle, a low-concentration standard solution bottle and a high-concentration standard solution bottle. The second multi-position selector valve is connected to the waste liquid barrel.

[0015] Furthermore, the solvent blowing module includes a six-way switching valve, an inert three-way switching valve and a solvent-driving chamber connected in sequence, the six-way switching valve is connected to the extraction liquid outlet of the extraction cover, the solvent-driving chamber is a U-shaped structure, the solvent-driving chamber includes a thin tube and a thick tube, the outlet end of the thin tube is located at the bottom of the thick tube, and upper and lower independent heating modules are provided outside the solvent-driving chamber. The six-way switching valve and the inert three-way switching valve are respectively connected to the waste liquid barrel, and an internal standard solution bottle and a first quantitative ring are also provided outside the six-way switching valve. The internal standard solution bottle is connected to the inert gas source, and the two ends of the first quantitative ring are respectively connected to the six-way switching valve.

[0016] Furthermore, the object to be tested focusing module includes an inert four-way switching valve, an inert six-way switching valve and a focusing tube connected in sequence, the inert four-way switching valve and the inert six-way switching valve are provided with a second temperature adjustment module outside, the focusing tube is provided with a third temperature adjustment module outside, the inert four-way switching valve is connected to the thick tube outlet end of the solvent-driving chamber, and the inert six-way switching valve is connected to the gas chromatograph-mass spectrometer.

[0017] Furthermore, a second three-way switching valve and a second inert gas input assembly are provided outside the inert four-way switching valve. The second three-way switching valve, the inert four-way switching valve and the second inert gas input assembly are connected via three-way connections, and the second three-way switching valve is connected to the waste liquid barrel.

[0018] Furthermore, the sampling efficiency investigation module includes a third multi-position selector valve, a third inert gas input assembly, a second substitute solution bottle and a second quantitative ring, the third inert gas input assembly, the second substitute solution bottle and the second quantitative ring are respectively connected to the third multi-position selector valve, both ends of the second quantitative ring are respectively connected to the third multi-position selector valve, one end of the second substitute solution bottle is connected to an inert gas source, the third multi-position selector valve is connected to the sampling cavity of the sampling area, and the third multi-position selector valve is connected to the waste liquid barrel.

[0019] Furthermore, the extraction solvent bottle is a sealed structure, and a one-way valve and a filter head are provided on the top of the extraction solvent bottle.

[0020] The beneficial effects of the present invention are: 1) The injection volume of the target object has been greatly increased, thereby reducing the detection limit and improving the sensitivity of the method. Substances with very low concentrations but requiring special attention can be detected, which can allow for less sampling volume and sampling time, and improve analysis efficiency. In this case, some substances with very low concentrations but high toxicity can be detected, which is of great significance for environmental monitoring. Moreover, the shortening of sampling time means higher monitoring "resolution". Multiple analyses can be performed in the same time. For example, the original method requires one sample and one set of data every 24 hours, but now one sample can be performed every 2 hours, and 12 sets of data can be performed every 24 hours. More precise data analysis can be achieved, and the judgment of air pollution conditions can be more accurate.

[0021] 2) It is easy to realize fully automatic unmanned work. It can completely liberate manpower, reduce the contact between people and toxic and harmful reagents, and facilitate the realization of Internet of Things and cloud data. It can not only be used for unmanned laboratories, but also facilitate the development of automatic monitoring devices for fixed pollution source exhaust gas or ambient air points.

[0022] 3) It is convenient to dispose of thermally unstable substances and substances that are easily deposited on the quartz surface and difficult to vaporize. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of step S1 in Example 1; Figure 2 is a schematic diagram of step S2 in Example 1; Figure 3 is a schematic diagram of step S3 in Example 1; Figure 4 is a schematic diagram of step S4 in Example 1; Figure 5 is a schematic diagram of step S5 in Example 1; Figure 6 is a schematic diagram of step S6 in Example 1; Figure 7is a schematic diagram of step S7 in Example 1; Figure 8 is a schematic diagram of step S8 in Example 1; Fig. 9 is a schematic diagram of step S9 in Example 1; Fig.10 is a schematic diagram of step S10 in Example 1; Fig.11 is a schematic diagram of step S11 in Example 1; Fig.12 is a schematic diagram of step S12 in Example 1; Fig.13 is a schematic diagram of step S13 in Example 1; Fig.14 is a schematic diagram of step S14 in Example 1; Fig.15 is a schematic diagram of step S15 in Example 1; Fig.16 is a schematic diagram of the sampling chamber in the present invention; Fig.17 Schematic diagram of the solvent-driving chamber in the present invention; Fig.18 is a schematic diagram of Example 2; Fig.19 is a schematic diagram of Example 2; Fig. 20 is a schematic diagram of step T2 in Example 3; Fig.21 is a schematic diagram of step T3 in Example 3; In the figure, the dotted line represents the workflow; In the figure, 1-automatic injection module, 101-waiting area, 102-sampling area, 103-extraction area, 11-automatic injection base, 12-sampling chamber, 121-sealing nut, 122-solid phase adsorption material, 123-export channel, 13-sampling cover, 131-sampling inlet, 132-sampling outlet, 14-extraction cover, 141-extraction liquid inlet, 142-extraction liquid outlet, 15-oil-free vacuum pump, 16-flow controller, 17-first three-way switching valve, 18-filter, 19-first temperature adjustment module, 2-sampling efficiency inspection module, 21-third multi-position selection valve, 22-third inert gas input assembly, 23-second substitute solution bottle, 24-second quantitative ring, 3-solvent addition module, 31-first inert gas input assembly, 32-first multi-position Selection valve, 33-second multi-position selection valve, 34-extraction solvent bottle, 341-one-way valve, 342-filter head, 35-first substitute solution bottle, 36-low concentration standard solution bottle, 37-high concentration standard solution bottle, 38-four-way, 4-solvent blowing module, 41-six-way switching valve, 42-inert three-way switching valve, 43-solvent driving chamber, 431-thin tube, 432-thick tube, 433-upper and lower independent heating modules, 44-internal standard solution bottle, 45-first quantitative loop, 5-analyte focusing module, 51-inert four-way switching valve, 52-inert six-way switching valve, 53-focusing tube, 54-second temperature adjustment module, 55-third temperature adjustment module, 56-second three-way switching valve, 57-second inert gas input assembly, 6-gas chromatograph-mass spectrometer, 7-waste liquid barrel. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0025] Embodiment 1: The present invention provides a technical solution: an automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas, comprising an automatic sampling module 1, a sampling efficiency investigation module 2, a solvent addition module 3, a solvent blowing module 4, a test object focusing module 5, a gas chromatograph-mass spectrometer 6 and a waste liquid barrel 7; The automatic sampling module 1 includes an automatic sampling base 11 and a sampling chamber 12. The automatic sampling base 11 includes a waiting area 101, a sampling area 102 and an extraction area 103. The plurality of sampling chambers 12 are respectively arranged in the waiting area 101, the sampling area 102 and the extraction area 103. The top of the sampling chamber 12 in the sampling area 102 is provided with a sampling cover 13 and a sampling assembly, and the top of the sampling chamber 12 in the extraction area 103 is provided with an extraction cover 14. The sampling efficiency inspection module 2 is connected to the sampling cover 13; the solvent addition module 3 is connected to the extraction cover 14; The extraction cover 14, the solvent blowing module 4, the analyte focusing module 5 and the gas chromatograph-mass spectrometer 6 are connected in sequence through pipelines; The waste liquid barrel 7 is connected to the solvent adding module 3 , the solvent blowing module 4 and the object focusing module 5 respectively.

[0026] According to the above technical scheme, the ambient air or exhaust gas is sampled by the automatic sampling module 1, and the semi-volatile organic compounds (SVOCs) in the sample are collected by the sampling chamber 12; then the solvent is added to the sampling chamber 12 by the solvent adding module 3, so that the collected semi-volatile organic compounds are dissolved in the organic solvent to obtain an extract; then the solvent in the extract is blown away by the solvent blowing module 4, and the semi-volatile organic compounds are vaporized at high temperature, and are condensed and enriched at low temperature by the focusing tube 53, and finally the focusing tube 53 is heated to make the enriched semi-volatile organic compounds quickly heat up and analyze, and are brought into the gas chromatograph-mass spectrometer 6 by the carrier gas in the gas chromatograph-mass spectrometer 6 for analysis.

[0027] Through the above technical solution, the sample that finally enters the gas chromatograph-mass spectrometer 6 is gas, while the sample that enters the analytical instrument in the traditional detection device is liquid. The advantages of gas injection in this method include the following points: (1) The injection volume of the target substance is greatly increased, thereby reducing the detection limit of the method and improving the sensitivity of the method. Substances with very low concentrations but requiring special attention can be detected, allowing for a smaller sampling volume and sampling time.

[0028] (2) It is easy to realize automated monitoring. The traditional method can only realize semi-automated monitoring, and each intermediate link requires human participation. In the process of processing SVOCs samples, volume determination is an indispensable operation link. At present, most intermediate pre-treatment equipment requires analysts to manually determine the volume and then load the sample on the machine by themselves. This method does not have steps such as volume determination, which is convenient for fully automatic unmanned operation.

[0029] The specific operation process includes steps S1-S15, such as Figure 1-Figure 15 As shown: Step S1, such as Figure 1As shown, at this time, a sealing cover is provided on the top of the sampling cavity 12 in the waiting area 101 to ensure that the interior of the unsampled sampling cavity 12 is pure. At the same time, the sampling cavity 12 and the sampling cover 13 in the sampling area 102 are in a state to be installed, and the extraction cover 14 and the corresponding sampling cavity 12 in the extraction area 103 are also in a state to be installed.

[0030] Specific reference Fig.16 , the inverted cone-shaped space of the sampling cavity 12 is provided with a filter membrane pressure ring, a filter membrane, a first support, a solid-phase adsorption material 122 and a second support in sequence from top to bottom, wherein the first support and the second support can be made of stainless steel mesh or metal sintered blocks, which can ensure that the sample can pass smoothly while supporting the interior. The solid-phase adsorption material 122 is accumulated between the first support and the second support, and is generally a spherical resin or silica gel ball. If the moisture content of the sample is high, a small amount of anhydrous sodium sulfate can be filled in the conical bottom layer inside the sampling cavity 12 to remove water. The filter membrane is made of polytetrafluoroethylene or quartz material. Preferably, a polytetrafluoroethylene filter membrane is used. Due to its hydrophobicity, liquid water cannot pass through, making it difficult for water in the gas sample to enter the solvent-removing cavity 43.

[0031] Furthermore, an outlet channel 123 is provided on one side of the top of the sampling cavity 12 , and the outlet channel 123 is communicated with the small end in the sampling cavity 12 .

[0032] For the sampling area 102, the sampling chamber 12 here is transferred from the sampling chamber 12 of the waiting area 101, and the sampling cover 13 is covered on the top of the sampling chamber 12, and then locked by the sealing nut 121. It can be known that a sealing ring is provided at the connection between the sampling cover 13 and the sampling chamber 12 to ensure air tightness. At the same time, since a sampling inlet 131 and a sampling outlet 132 are provided on the top of the sampling cover 13, the sampling inlet 131 is connected to the sampling chamber 12, and sampling is performed through the sampling inlet 131; the sampling outlet 132 corresponds to and is connected to the outlet channel 123, and the excess exhaust gas is discharged through the sampling outlet 132.

[0033] For the extraction area 103, the sampling chamber 12 here is transferred from the sampling chamber 12 after the sampling in the sampling area 102 is completed. The sampling cover 13 is removed and the extraction cover 14 is covered on the top of the sampling chamber 12, and then locked by the sealing nut 121. Similarly, a sealing ring is also provided at the connection between the extraction cover 14 and the sampling chamber 12. At the same time, an extraction liquid inlet 141 and an extraction liquid outlet 142 are provided on the top of the extraction cover 14. The extraction liquid inlet 141 is also connected to the sampling chamber 12. The solvent is added through the extraction liquid inlet 141, and the extraction liquid outlet 142 corresponds to and is connected to the outlet channel 123, so that the extraction liquid formed after adding the organic solvent enters the solvent blowing module 4 from the extraction liquid outlet 142.

[0034] Step S2, such as Figure 2As shown, at this time, the sampling chambers 12 of the sampling area 102 and the extraction area 103 are assembled, and the sampling inlet 131 is connected to the main sampling tube or an independent sampling tube and connected to the local atmosphere. At this time, the first temperature adjustment module 19 outside the sampling area 102 is in a refrigeration state, and the temperature is controlled to 5±2°C. Since the two groups of oil-free air pumps 15 and the flow controller 16 are respectively connected to the first three-way switching valve 17, a group of oil-free air pumps 15 and flow controllers 16 are started at this time (the two groups of oil-free air pumps 15 and flow controllers 16 are used alternately to extend the life of the electrical appliances), and the ambient air is collected at a constant flow rate. Preferably, the maximum gas collection flow rate is 100L / min, and the longest gas collection time is 24h. If the waste gas from a fixed pollution source is collected, the sampling inlet 131 is connected to the waste gas sampling tube, and the sampling flow rate and time are reduced accordingly. For example, the gas collection flow rate is 0.5L / min, and the gas collection time is set to 1h. Furthermore, a filter 18 is provided between the first three-way switching valve 17 and the sampling outlet 132 , and the filter 18 can effectively filter impurities to protect the switching valve, the flow meter and the injection pump.

[0035] Continue as Figure 2 As shown, at this time, the sampling area 102 is in a continuous sampling state. At this time, the second multi-position selection valve 33 is switched to the hole position connected to the first substitute solution bottle, and 100 μL of substitute solution is extracted through the corresponding injection pump, and then the extracted substitute is injected into the sampling cavity 12 of the extraction area 103.

[0036] Step S3, such as Figure 3 As shown, the sampling area 102 keeps sampling. The second multi-position selector valve 33 extracts 200 μL of extraction liquid from the extraction solvent bottle 34 to clean the pipeline and then discharges it into the waste liquid bucket 7. After cleaning, the second multi-position selector valve 33 switches to the dead blocking position.

[0037] Furthermore, the extraction solvent bottle 34 is a sealed structure, and a one-way valve 341 and a filter head 342 are provided on the top of the extraction solvent bottle 34 .

[0038] Through the above technical solution, after the extraction solvent bottle 34 is drawn, the inside of the bottle is in a negative pressure state, and the one-way valve 341 is opened, and the external air will enter the extraction solvent bottle 34 to maintain the air pressure balance. At the same time, the air from the outside entering the bottle will be adsorbed and purified by the filter head 342 to prevent impurities such as organic matter from entering.

[0039] Continue as Figure 3As shown, since the first multi-position selector valve 32, the second multi-position selector valve 33, the first inert gas input assembly 31 and the extract inlet 141 are connected through the four-way 38, the first multi-position selector valve 32 is switched to extract the extract through the injection pump and inject it into the sampling chamber 12 of the extraction area 103. The extract can be a mixture of n-hexane and acetone, or dichloromethane and acetone. The extracted extract immerses the solid phase adsorption material 122 and the filter membrane. The volume of the added extract is related to the volume of the remaining space of the sampling chamber 12. Generally speaking, the volume of the added extract should be within 100mL, and the specific volume can be adjusted according to actual conditions. When the extract is added to half of the set volume, the electromagnetic switch valve of the extraction cover 14 is opened to allow the residual gas in the sampling chamber 12 to be discharged, and the outlet of the electromagnetic switch valve can be connected to the activated carbon adsorption tube. After reaching the set volume of the entire extract injected, the electromagnetic switch valve is closed to make the sampling chamber 12 completely closed, and the first multi-position selector valve 32 is switched to the dead blocking position.

[0040] Step S4, such as Figure 4 As shown, the sampling area 102 keeps sampling. The extraction area 103 heats the corresponding sampling cavity 12 through the first temperature adjustment module 19. Specifically, heating can be carried out in the following two ways: 1. Ultrasonic heating method: the extraction area 103 starts to heat, and the temperature is slightly lower than the atmospheric boiling point of the extraction liquid by 2~4°C, and the ultrasonic element set in the automatic sampling base 11 is used to transmit ultrasound to the sampling cavity 12; 2. High temperature and high pressure method: the extraction area 103 starts to heat, and the temperature generally does not exceed 100°C (such as 100°C boiling point, acetone corresponds to 373kPa, n-hexane 244kPa, and dichloromethane 570kPa). At this time, due to the sealing of the cavity, the extraction liquid is still in liquid state, and the high temperature promotes the dissolution of the target. The single extraction time of the sampling cavity 12 of the extraction area 103 is determined according to the debugging results, and generally does not exceed 1h.

[0041] Step S5, such as Figure 5 As shown, the sampling area 102 keeps sampling. The sampling chamber 12 of the extraction area 103 stops the heating, ultrasonic and other extraction actions. The six-way switching valve 41 and the inert three-way switching valve 42 are connected, so that the solvent in the sampling chamber 12 flows into the solvent-driving chamber 43 due to the pressure difference, reducing the pressure in the system to avoid the loss of the extracting liquid due to excessive flow rate; keep this state for about 1 minute, and after the pressure is basically balanced, connect the inert four-way switching valve 51 and the second three-way switching valve 56 to connect it with the waste liquid bucket 7. Start the first inert gas input component 31, where the inert gas source used by the first inert gas input component 31 is nitrogen, and the first inert gas input component 31 is also provided with a gas flow controller, which presses all the extracting liquid in the sampling chamber 12 into the solvent-driving chamber 43 at a lower flow rate (not exceeding 40mL / min). If multiple extractions are required, repeat steps S3 to S5. Generally, the number of extractions does not exceed 2 times.

[0042] Step S6, as Figure 6 As shown, sampling continues. An electromagnetic valve is provided between the internal standard solution bottle 44 and the inert gas source, and by opening the electromagnetic valve, the internal standard liquid is pressed into the first quantitative loop 45 using a pressure difference. After ensuring that the internal standard liquid completely replaces the material in the first quantitative loop 45, the electromagnetic valve is closed. Preferably, the inert gas source adopts nitrogen, and the first quantitative loop 45 adopts 10 μL, and adding 5 times the volume of the quantitative loop is enough to ensure complete replacement, i.e. 50 μL.

[0043] Step S7, Figure 7 As shown, sampling continues. At this time, the first inert gas input assembly 31 in the solvent addition module 3 is connected to the sampling chamber 12 of the extraction area 103, and the first inert gas input assembly 31 is used to introduce all the internal standard liquid in the first quantitative loop 45 into the solvent chamber 43. The preferred nitrogen flow rate is about 40mL / min, and the ventilation is about 1min.

[0044] Step S8, Figure 8 As shown, sampling continues. Since the solvent removal chamber 43 is provided with upper and lower independent heating modules 433, the heating module below the solvent removal chamber 43 starts to heat independently at this time, and the heating rate is not higher than 10°C / min, and the temperature is controlled to 2~5°C below the boiling point of the extract. The upper part of the solvent removal chamber 43 does not start heating. Fig.17 As shown, since the solvent-driving chamber 43 includes a thin tube 431 and a thick tube 432, the outlet end of the thin tube 431 is located at the bottom of the thick tube 432, the high-purity nitrogen gas of the first inert gas input assembly 31 brings all the liquid in the thin tube into the thick tube, and the extract is all gathered in the thick tube. At the same time, some target substances that have a low boiling point and are vaporized will condense on the upper part of the thick tube 432 of the solvent-driving chamber 43; the high-purity nitrogen gas of the first inert gas input assembly 31 continues to purge the extract in the solvent-driving chamber 43, with a flow rate not exceeding 40 mL / min, and the solvent in the solvent-driving chamber 43 is purged into the waste liquid barrel 7, and semi-volatile organic compounds (SVOCs) remain in the solvent-driving chamber 43.

[0045] The solvent in the solvent removal chamber 43 is purged and removed, or the remaining solvent is no more than 0.1 mL. If the target contains SVOCs with relatively low boiling points, when the remaining solvent is only a few milliliters, heating can be stopped and purged at room temperature.

[0046] Furthermore, an observation hole is provided outside the thick tube 432 of the solvent chamber 43, through which the time of completion of purging can be observed and recorded, and set in the program, and the subsequent operations can be carried out according to this time; or sensors and other components can be provided to automatically determine whether the solvent has been blown away cleanly, thereby realizing automation.

[0047] Step S9, as Fig. 9As shown, sampling continues. The focusing tube 53 is temperature-controlled to -30°C by the third temperature regulating module 55. The upper and lower heating zones of the solvent-driving chamber 43 are all turned on, and the temperature is raised to 400-450°C at a rate of about 5°C / min, and the temperature is kept constant. The high-purity nitrogen flow rate in the first inert gas input assembly 31 is 20mL / min, and the SVOCs in the solvent-driving chamber 43 are vaporized and blown into the focusing tube 53, where they are condensed and adsorbed.

[0048] Step S10, as Fig.10 As shown, sampling continues. The focusing tube 53 is heated to 400° C. at a rate of not less than 60° C. / min. The inert six-way valve is switched, and the SVOCs in the focusing tube 53 are introduced into the GC / MS analysis using the carrier gas of the gas chromatograph-mass spectrometer 6 (GC / MS).

[0049] At the same time, the first multi-position selector valve 32 draws the extracting liquid in the extraction solvent bottle 34 into the sampling cavity 12 of the extraction area 103 for cleaning the solvent cavity 43. At this time, the extracting liquid does not need to fill the sampling cavity 12, and the volume of the extracted extracting liquid is 10-50 mL.

[0050] Step S11, as Fig.11 As shown, sampling continues. The extracting liquid in the sampling chamber 12 is pressed into the solvent-driving chamber 43 through the first inert gas input assembly 31. The inert gas flow blows all the liquid in the thin tube into the thick tube. Since the solvent-driving chamber 43 is U-shaped, all the liquid gathers at the bottom of the thick tube. At this time, the lower heating zone of the solvent-driving chamber 43 is heated to a slight boiling of the extracting liquid, so that the solvent evaporates to clean the inner wall of the upper half of the solvent-driving chamber 43 that is not soaked. Because of the temperature difference, the solvent will condense and flow down in the upper half, cleaning any residue that may exist on the inner wall. The process lasts for several minutes. This step can also be performed in step S10 to save time.

[0051] Step S12, as Fig.12As shown, sampling continues. The inert gas source of the second inert gas input assembly 57 uses nitrogen, and the second inert gas input assembly 57 is provided with a nitrogen pressure reducing valve, a gas flow controller and a solenoid valve. The temperature of the solvent-driving chamber 43 is kept rising as a whole through the upper and lower independent heating modules 433, the second inert gas input assembly 57, the second three-way switching valve 56, the inert four-way switching valve 51 and the solvent-driving chamber 43 are connected, the second inert gas input assembly 57 is enabled, nitrogen is introduced, and the extraction liquid in the solvent-driving chamber 43 is slowly pressed at a flow rate of about 30 mL / min along the inert three-way switching valve 42 and the six-way switching valve 41 into the waste liquid barrel 7. When the extraction liquid used to clean the solvent-driving chamber 43 is completely emptied, the nitrogen flushing of the second inert gas input assembly 57 is still maintained. The temperature of the solvent-driving chamber 43 gradually rises from low to high, and finally rises to 400°C, and then the temperature is no longer controlled, and then the temperature is kept falling (the specific heating program and the maximum temperature can be determined according to the debugging experiment). When the temperature of the solvent chamber 43 drops to about 60° C., the nitrogen flushing of the second inert gas input assembly 57 is stopped.

[0052] Step S13, as Fig.13 As shown, sampling continues. The inert six-way switching valve 52 is flushed with nitrogen through the second inert gas input assembly 57 at a flow rate of about 40 mL / min for 1 min.

[0053] Step S14, as Fig.14 As shown, sampling continues. The inert six-way switching valve 52 is flushed through the second inert gas input component 57 at a flow rate of about 40 mL / min. After 5 minutes, the focusing tube 53 is no longer temperature controlled and continues to cool down. When the temperature of the focusing tube 53 drops by about 80°C, the second inert gas input component 57 is stopped. Long-term high temperature affects the life of electrical appliances.

[0054] It can be known that the second temperature regulating module 54 maintains a constant temperature of 300° C. during the process of step S1 to step S13. The second temperature regulating module 54 mainly heats the inert four-way switching valve 51 and the inert six-way switching valve 52 and the connected pipelines to prevent the extract from condensing on the connected pipelines. Fig.14 After the process, the heating of the second temperature adjustment module 54 can be stopped.

[0055] Step S15, as Fig.15 As shown, sampling in the sampling area 102 is completed, and the sampling assembly and the first temperature adjustment module 19 are closed. The sampling chamber 12 in the extraction area 103 is moved to the waiting area 101 through the automatic sampling base 11, and the sampling chamber 12 in the sampling area 102 is moved to the extraction area 103, and the next sampling chamber 12 in the waiting area 101 is moved to the sampling area 102. The next round of gas sampling and analysis begins. At this time, the second temperature adjustment module 54 is restarted and kept heated to 300°C.

[0056] Embodiment 2: Based on step S2 in Example 1, a solution for adding a substitute during the sampling process is provided.

[0057] Specific reference Fig.18 and Fig.19 ,like Fig.18 As shown, the third multi-position selector valve 21 is switched to connect the second substitute solution bottle 23 and the second quantitative ring 24. Since one end of the second substitute solution bottle 23 is connected to the inert gas source, the inert gas source uses nitrogen. At the same time, a solenoid valve is provided between the second substitute solution bottle 23 and the inert gas source. The solenoid valve is opened to allow the substitute solution in the second substitute solution bottle 23 to flow into the second quantitative ring 24 under the action of the pressure difference and fully replace the material inside the second quantitative ring 24. After the replacement is sufficient, the solenoid valve is closed.

[0058] like Fig.19 As shown, the third multi-position selector valve 21 is switched, and the third inert gas input assembly 22 is started. The inert gas source of the third inert gas input assembly 22 is nitrogen. The third inert gas input assembly 22 is provided with a nitrogen pressure reducing valve, a solenoid valve and a flow limiting valve. The solenoid valve is opened, and nitrogen is controlled by the flow limiting valve to fill the substitute solution in the second quantitative ring 24 into the sampling chamber 12 at a rate of about 20 mL / min. After ensuring that the substitute solution in the second quantitative ring 24 is fully filled, the solenoid valve and the third multi-position selector valve 21 are closed.

[0059] Since the sampling process surrogate is added during sampling, it is different from the addition of surrogate during extraction (adding surrogate in step S2). The former can evaluate the recovery rate of the target in the whole process through the recovery rate of the surrogate, while the latter can only evaluate the recovery rate starting from the extraction step. Therefore, in terms of comprehensiveness, the former is more important, while the latter is also meaningful. The combination of the two can analyze the recovery rate of the two key steps of sampling and extraction. During the sampling process, surrogate can be added multiple times at equal time intervals and repeated. Figure 18-19 If repeated addition is required, the concentration of the substitute solution should be prepared to be 1 / n of that added once (n is the number of additions).

[0060] Embodiment 3: Based on Example 1, a scheme of a working curve quantitative method mode is provided, which includes steps T1 to T15. Only the sampling cavity 12 of the extraction area 103 participates in the whole process, and the sampling cavity 12 of the sampling area 102 no longer maintains continuous sampling.

[0061] Step T1 is the same as step S1.

[0062] Step T2, see Fig. 20The sampling chamber 12 of the sampling area 102 does not participate in the sampling, the second multi-position selector valve 33 is connected to the extraction solvent bottle 34, the extraction liquid is drawn to clean the pipeline, and then discharged into the waste liquid barrel 7, and this is repeated 2 to 3 times.

[0063] Step T3, adding standard solution, as follows Fig.21 As shown, the second multi-position selector valve 33 is connected to the low-concentration standard solution bottle 36 and the high-concentration standard solution bottle 37 respectively, and the standard solution is added in a cycle from the low-concentration standard solution to the high-concentration standard solution. For example, 6 working curve points are drawn, and the concentration difference between the low-concentration standard solution bottle 36 and the high-concentration standard solution bottle 37 is set to 20 times (the standard solution includes the setting of the substitute concentration), and 100μL, 200μL, and 500μL of the low-concentration standard solution are taken, and 100μL, 200μL, and 500μL of the high-concentration standard solution are taken.

[0064] In the process of drawing working curve points, first, the second multi-position selector valve 33 is connected to the low-concentration standard solution bottle 36, and 100 μL of standard solution is first extracted to clean the pipeline and then discharged into the waste liquid barrel 7; the set volume of low-concentration standard solution is extracted again and injected into the sampling cavity 12, and steps T4 to T15 are performed; after the standard solution is injected, the second multi-position selector valve extracts 100 μL of extraction liquid to clean the pipeline and then discharge it into the waste liquid barrel 7. After completion, the second multi-position selector valve 33 is switched to the dead blocking position.

[0065] Step T4 is the same as step S3 except that the sampling cavity 12 of the sampling area 102 does not participate in the sampling.

[0066] Step T5 is the same as step S4 except that the sampling cavity 12 of the sampling area 102 does not participate in the sampling.

[0067] Step T6 is the same as step S5 except that the sampling cavity 12 of the sampling area 102 does not participate in the sampling.

[0068] Step T7 is the same as step S6 except that the sampling cavity 12 of the sampling area 102 does not participate in the sampling.

[0069] Step T8 is the same as step S7 except that the sampling cavity 12 of the sampling area 102 does not participate in the sampling.

[0070] Step T9, except that the sampling cavity 12 of the sampling area 102 does not participate in the sampling, the rest is the same as step S9.

[0071] Step T11, except that the sampling cavity 12 of the sampling area 102 does not participate in sampling, the rest is the same as step S10.

[0072] Step T12, except that the sampling cavity 12 of the sampling area 102 does not participate in sampling, the rest is the same as step S11.

[0073] Step T13, except that the sampling cavity 12 of the sampling area 102 does not participate in sampling, the rest is the same as step S12.

[0074] Step T14, except that the sampling cavity 12 of the sampling area 102 does not participate in sampling, the rest is the same as step S13.

[0075] Step T15, except that the sampling cavity 12 of the sampling area 102 does not participate in sampling, the rest is the same as step S14. After this step is completed, it indicates that the working curve point is drawn. If the filter membrane and the solid phase adsorption material 122 in the sampling cavity 12 are not damaged, the sampling cavity 12 of the extraction area 103 can still be used to add the standard solution of the next curve point from step T3, and so on until the curve is drawn.

[0076] Compared with the standard curve quantification method, the working curve quantification method can eliminate the errors caused by the extraction, concentration, injection and other links of the target object. Except for the sampling part, the other operation steps are consistent with the analyte, which reflects most of the analysis process. If there is a loss of the target object, there will be a certain loss at different concentration points. The working curve quantification can better reflect the actual concentration level of the analyte in the sample, and the quantitative result is more accurate under the condition of equivalent linearity.

[0077] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. An automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas, characterized in that: It includes an automatic sampling module (1), a sampling efficiency testing module (2), a solvent adding module (3), a solvent blowing module (4), an analyte focusing module (5), a gas chromatograph-mass spectrometer (6) and a waste liquid bucket (7); The automatic sampling module (1) comprises an automatic sampling base (11) and a sampling chamber (12); the automatic sampling base (11) comprises a waiting area (101), a sampling area (102) and an extraction area (103); a plurality of sampling chambers (12) are arranged in the waiting area (101), the sampling area (102) and the extraction area (103), respectively; the sampling chamber (12) in the waiting area (101) has a cover on the top; the sampling chamber (12) in the sampling area (102) has a sampling cover (13) and a sampling assembly on the top; and the sampling chamber (12) in the extraction area (103) has an extraction cover (14) on the top; The sampling efficiency investigation module (2) is connected to the sampling cover (13); the solvent addition module (3) is connected to the extraction cover (14); The extraction cover (14), the solvent blowing module (4), the analyte focusing module (5) and the gas chromatograph-mass spectrometer (6) are connected in sequence through pipelines; The waste liquid barrel (7) is respectively connected to the solvent adding module (3), the solvent blowing module (4) and the object to be tested focusing module (5).

2. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 1, characterized in that: The sampling cavity (12) and the automatic injection base (11) are fixed by plugging, a first temperature regulating module (19) is provided outside the sampling area (102) and the extraction area (103), a heat insulation plate is provided between the sampling area (102) and the extraction area (103), the sampling cavity (12) is an inverted cone structure, and a filter membrane pressure ring, a filter membrane, a first support member, a solid phase adsorption material (122) and a second support member are provided in sequence from top to bottom in the sampling cavity (12), and an outlet channel (123) is provided on one side of the top of the sampling cavity (12), and the outlet channel (123) is communicated with a small end in the sampling cavity (12).

3. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 2, characterized in that: The sampling cover (13) and the extraction cover (14) are connected to the corresponding sampling chamber (12) via a sealing nut (121), respectively; a sampling inlet (131) and a sampling outlet (132) are provided at the top of the sampling cover (13); the sampling inlet (131) is located at the center of the sampling cover (13) and is in communication with the corresponding sampling chamber (12); the sampling outlet (132) corresponds to and is in communication with the outlet channel (123); An extraction liquid inlet (141) and an extraction liquid outlet (142) are provided at the top of the extraction cover (14); the extraction liquid inlet (141) is located at the center of the extraction cover (14) and is in communication with the corresponding sampling cavity (12); the extraction liquid outlet (142) corresponds to and is in communication with the outlet channel (123); and the extraction liquid inlet (141) is provided with an electromagnetic switch valve.

4. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 3, characterized in that: The sampling assembly comprises an oil-free air pump (15), a flow controller (16), a first three-way switching valve (17) and a filter (18); the two groups of the oil-free air pump (15) and the flow controller (16) are respectively connected to the first three-way switching valve (17); one end of the first three-way switching valve (17) is connected to the sampling outlet (132); and the filter (18) is located between the first three-way switching valve (17) and the sampling outlet (132).

5. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 4, characterized in that: The solvent addition module (3) comprises a first inert gas input assembly (31), a first multi-position selector valve (32), a second multi-position selector valve (33) and an extraction solvent bottle (34); the first multi-position selector valve (32), the second multi-position selector valve (33), the first inert gas input assembly (31) and the extraction liquid inlet (141) are connected via a four-way (38); the extraction solvent bottle (34) is connected to the first multi-position selector valve (32) and the second multi-position selector valve (33), respectively; the first multi-position selector valve (32) and the second multi-position selector valve (33) are both provided with an injection pump; the second multi-position selector valve (33) is also provided with a first substitute solution bottle (35), a low-concentration standard solution bottle (36) and a high-concentration standard solution bottle (37); the second multi-position selector valve (33) is connected to the waste liquid barrel (7).

6. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 3, characterized in that: The solvent removal module (4) comprises a six-way switching valve (41), an inert three-way switching valve (42) and a solvent-removing chamber (43) which are connected in sequence. The six-way switching valve (41) is connected to the extraction liquid outlet (142) of the extraction cover (14). The solvent-removing chamber (43) is a U-shaped structure. The solvent-removing chamber (43) comprises a thin tube (431) and a thick tube (432). The outlet end of the thin tube (431) is located at the bottom of the thick tube (432). An upper and lower independent heating module (433) is arranged outside the solvent-removing chamber (43). The six-way switching valve (41) and the inert three-way switching valve (42) are respectively connected to the waste liquid barrel (7). An internal standard solution bottle (44) and a first quantitative ring (45) are also arranged outside the six-way switching valve (41). The internal standard solution bottle (44) is connected to an inert gas source. Both ends of the first quantitative ring (45) are respectively connected to the six-way switching valve (41).

7. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 6, characterized in that: The analyte focusing module (5) comprises an inert four-way switching valve (51), an inert six-way switching valve (52) and a focusing tube (53) which are connected in sequence; the inert four-way switching valve (51) and the inert six-way switching valve (52) are provided with a second temperature regulating module (54) outside; the analyte focusing tube (53) is provided with a third temperature regulating module (55) outside; the inert four-way switching valve (51) is connected to an outlet end of a thick tube (432) of the solvent-driving chamber (43); and the inert six-way switching valve (52) is connected to the gas chromatograph-mass spectrometer (6).

8. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 7, characterized in that: A second three-way switching valve (56) and a second inert gas input assembly (57) are also provided outside the inert four-way switching valve (51); the second three-way switching valve (56), the inert four-way switching valve (51) and the second inert gas input assembly (57) are connected via a three-way connection; the second three-way switching valve (56) is connected to the waste liquid barrel (7).

9. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 1, characterized in that: The sampling efficiency investigation module (2) comprises a third multi-position selector valve (21), a third inert gas input assembly (22), a second substitute solution bottle (23) and a second quantitative ring (24); the third inert gas input assembly (22), the second substitute solution bottle (23) and the second quantitative ring (24) are respectively connected to the third multi-position selector valve (21); both ends of the second quantitative ring (24) are respectively connected to the third multi-position selector valve (21); one end of the second substitute solution bottle (23) is connected to an inert gas source; the third multi-position selector valve (21) is communicated with the sampling chamber (12) of the sampling area (102); and the third multi-position selector valve (21) is connected to the waste liquid barrel (7).

10. The automatic monitoring system for semi-volatile organic compounds in ambient air and exhaust gas according to claim 5, characterized in that: The extraction solvent bottle (34) is a sealed structure, and a one-way valve (341) and a filter head (342) are provided on the top of the extraction solvent bottle (34).

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