Atmospheric trace nitrous acid and formaldehyde profile detection device carried by small aircraft and detection method

Abstract

The invention relates to the field of atmospheric environment monitoring and high-altitude sampling, and discloses an atmospheric trace nitrous acid and formaldehyde profile detection device carried by a small aircraft and a detection method. The absorption liquid is fed into the double-channel miniature spiral trapping trap through a peristaltic pump to be mixed and contacted with the sample gas to form a sample solution; a liquid storage bottle is arranged on the automatic sample disc, and the top of the first liquid inlet needle is connected with a liquid outlet of the dual-channel miniature spiral trapping trap; a color developing solution in the color developing solution storage bottle is injected into the liquid storage bottle through a second liquid inlet needle, and the constant-temperature reaction kettle controls the color developing reaction temperature to form a sample solution to be detected; a to-be-detected sample solution is pumped into the absorption cell through the liquid pumping needle, and the liquid pumping needle is driven by the liquid pumping arm to move up and down; the absorption cell is connected with a detector, and the detector is used for detecting the component concentration of the sample solution to be detected; the automatic sampler and the rapid reaction detector comprise the same automatic sample disc to realize rapid sample transfer.

Description

Technical Field

[0001] This invention relates to the field of atmospheric environment monitoring and high-altitude sampling technology, and in particular to a detection device and method for detecting atmospheric trace nitrite (HONO) and formaldehyde (HCHO) profiles carried by small aircraft. Background Technology

[0002] HONO and HCHO, as important precursors of OH radicals, are directly related to the strength of atmospheric oxidation. Therefore, studying the impact of monitoring HONO and HCHO in urban areas on O3 generation, free radical chemistry, and atmospheric oxidation is a necessary prerequisite for clarifying the causes of urban ozone pollution and improving atmospheric chemical models. The distribution of reactive pollutants such as HONO and HCHO is not uniform in both vertical and horizontal directions, mainly due to two factors: firstly, these pollutants are in a continuous dynamic process of generation, transport, and transformation; secondly, the diurnal variation of atmospheric boundary layer height significantly affects the diffusion patterns of pollutants. Vertical and horizontal profile measurements of HONO and HCHO can provide indispensable three-dimensional data support for atmospheric oxidation studies. First, profile measurements can reveal vertical stratification differences in atmospheric oxidation, deepening our understanding of chemical processes. Second, they can provide the concentration distribution of free radical precursors at different altitudes, thereby quantifying the source and sink contributions of free radicals at each altitude and improving atmospheric chemical models. Third, the transboundary transport of upper-air pollutants significantly alters the oxidative levels of downstream regions, and HONO and HCHO profile data are key indicators for tracking this process. Furthermore, HONO and HCHO profile data can enable precise diagnosis of pollution causes, providing a basis for stratified control and facilitating the coordinated prevention and control of oxidative stress and pollution, leading to the development of refined governance strategies.

[0003] Among existing methods for observing the profiles of HONO and HCHO, multi-axis differential absorption spectroscopy (MAX-DOAS) can achieve direct ground-based measurement of pollutant concentration profiles, but it has a high detection limit and is dependent on sunlight intensity. Observation tower pods carrying pollutant detection devices can achieve high-resolution detection of lower concentrations of pollutants, but their application scenarios are extremely limited, only allowing vertical observations in fixed areas with observation towers, and cannot be flexibly deployed to key areas such as towerless urban core pollution zones and complex terrain areas. Aircraft-borne pollutant monitoring systems offer wide coverage and can perform multi-parameter measurements, acquiring full-altitude profile data from near-ground to the upper troposphere, but they are extremely costly, making high-frequency, routine observations difficult; they are also restricted by flight routes and airspace control, hindering flexible fixed-point, intensive observations; and they require highly skilled observation teams.

[0004] In recent years, small aircraft such as drones equipped with detection devices have become a new means of measuring high-altitude atmospheric pollutants. However, the carrying capacity and flight time of drones are very limited (within 1 hour for a single flight), and they can only carry some small pollutant detectors to measure conventional pollutants such as PM 2.5 , PM 10 , SO2, and higher-concentration pollutants such as CO2 and CH4. For the two trace components (ppt) of HONO and HCHO that require high-precision detection, the existing spectroscopic measurement instruments are relatively heavy, and the optical components are sensitive to vibration; the wet chemical method can achieve a detection limit of ppt for HONO and HCHO in the air, but it requires a large amount of reagent solution, occupying additional load, and the solution pipeline is long, with a large dead volume, and the data has a certain lag. There is currently no device that can be carried by a small aircraft. To break through the detection bottleneck of low-concentration pollutants, a technical idea of separating sampling and detection can be adopted, that is, using a drone to carry a sampling tank or sampling bottle to collect high-altitude samples. Currently, there are related technologies that can complete the sample collection of pollutants such as VOCs, O3, NO x by carrying a sampling bottle with a drone. However, such a scheme needs to bring the sample back to the laboratory for concentration detection, with poor timeliness and complex operation. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a detection device and detection method for the profiles of atmospheric trace nitrous acid and formaldehyde carried by a small aircraft, which can achieve lightweight, trace-level (ppt-level), automated, portable, and real-time detection. At the same time, it realizes the rapid switching and linkage of air sampling and ground detection.

[0006] To achieve the above objectives, in a first aspect, the technical solution adopted by the present invention is as follows: a detection device for atmospheric trace nitrite and formaldehyde profiles mounted on a small aircraft, comprising: an automatic sampler mounted on the small aircraft, including a sample gas collector and an automatic sample storage device; the sample gas collector includes an absorbent storage bottle and a dual-channel micro-spiral trap, wherein the absorbent in the absorbent storage bottle is fed into the dual-channel micro-spiral trap by a peristaltic pump, and the sample gas enters the dual-channel micro-spiral trap and mixes with the absorbent in the dual-channel micro-spiral trap to form a sample solution; the automatic sample storage device includes an automatic sample tray, wherein multiple pairs of storage bottles are arranged circumferentially on the automatic sample tray, the automatic sample tray is placed on a first turntable, and is driven to rotate automatically by a first reduction stepper motor mounted on the first turntable; a pair of first liquid inlet needles are arranged above the automatic sample tray, and the top of each first liquid inlet needle is connected to the dual-channel micro-spiral trap via a pipeline. The system has two outlets connected. The first inlet needle, driven by the first inlet arm, moves up and down to inject the sample solution into the storage bottle. The rapid reaction detector is located on the ground and includes an automatic reaction injector and a detection mechanism. The detection mechanism includes a defoamer and an absorption cell. The automatic reaction injector includes a colorimetric solution storage bottle and an automatic sample tray placed on a second turntable. It rotates automatically via a second reduction stepper motor mounted on the second turntable, which is placed in a constant-temperature reaction vessel. A pair of second inlet needles are located above the second turntable. The colorimetric solution in the storage bottle is injected through the second inlet needles into the storage bottle on the automatic sample tray to collect the sample solution, forming the sample solution to be tested. The second inlet needles move up and down driven by the second inlet arm. The sample solution to be tested is extracted into the absorption cell through a pair of extraction needles, which move up and down driven by the extraction arm. The absorption cell is connected to a detector, which detects the component concentration of the sample solution to be tested.

[0007] Furthermore, the sample gas collector also includes a liquid flow meter, a first three-way valve, and a safety bottle;

[0008] The absorbent storage bottle is connected to the inlet of a liquid flow meter via a solution pipeline. The outlet of the liquid flow meter is connected to the inlet of the first three-way valve. The liquid flow meter monitors and controls the solution volume. The two outlets of the first three-way valve are connected to the first and second channel inlets of the dual-channel micro-spiral trap, respectively. The outlet of the dual-channel micro-spiral trap is connected to the inlet of a safety bottle. Abnormal liquid accumulation is discharged through the safety bottle. The first and second channel outlets of the dual-channel micro-spiral trap are connected to the corresponding first inlet needles via solution pipelines.

[0009] Furthermore, the peristaltic pump adopts a four-channel peristaltic pump; the first channel of the four-channel peristaltic pump is connected to the first tee and the first channel inlet of the dual-channel micro-spiral trap; the second channel of the four-channel peristaltic pump is connected to the first tee and the second channel inlet of the dual-channel micro-spiral trap; the third channel of the four-channel peristaltic pump is connected to the first channel outlet of the dual-channel micro-spiral trap and the inlet of the first inlet needle of the inlet arm; and the fourth channel of the four-channel peristaltic pump is connected to the second channel outlet of the dual-channel micro-spiral trap and the inlet of the second inlet needle of the inlet arm.

[0010] Furthermore, the outlet of the dual-channel micro-spiral trap is connected to a safety bottle, the upper exhaust port of the safety bottle is connected to a gas flow meter and a gas pump in sequence, and the bottom liquid outlet of the safety bottle is connected to a waste liquid pool via a waste liquid pump, which pumps the waste liquid into the waste liquid pool; a gas flow meter is installed at the outlet of the safety bottle.

[0011] Furthermore, one end of the first inlet arm is provided with a first inlet needle clamping hole, and the other end of the first inlet arm is connected to a first lead screw, which is connected to a first stepper motor. The first stepper motor drives the first lead screw to rotate, thereby controlling the first inlet arm.

[0012] Furthermore, one end of the second liquid inlet arm is provided with a second liquid inlet needle clamping hole, and the other end of the second liquid inlet arm is connected to a second lead screw, which is connected to a second stepper motor; one end of the liquid extraction arm is provided with a liquid extraction needle clamping hole, and the other end of the liquid extraction arm is connected to a third lead screw, which is connected to a third stepper motor.

[0013] Furthermore, two absorption cells are configured, both of which are long-path colorimetric cells; and a light source is provided outside each long-path colorimetric cell. The testing mechanism also includes a second three-way valve and a defoamer; the colorimetric solution storage bottle is connected to the inlet of a pair of second inlet needles on the second inlet arm via the second three-way valve, and the outlet of the pair of second inlet needles is respectively aligned with the caps of the storage bottles on the outer and inner rings of the automatic sample tray; the inlet of a pair of suction needles on the suction arm is aligned with the caps of the storage bottles on the outer and inner rings of the automatic sample tray; the outlet of the pair of suction needles is respectively connected to the inlet of a defoamer, and the outlet of the defoamer is respectively connected to the inlet of the absorption cell; the light source is connected to the light inlet of the absorption cell via an optical fiber, and the detector is connected to the light outlet of the absorption cell via an optical fiber.

[0014] Secondly, the technical solution adopted by the present invention is as follows: a method for detecting atmospheric trace nitrite and formaldehyde profiles on a small aircraft, based on the aforementioned detection device for atmospheric trace nitrite and formaldehyde profiles on a small aircraft, comprising: preparing an absorption liquid and a colorimetric solution; mounting an automatic sampler on a small aircraft, placing a storage bottle in an automatic sample tray, adjusting the automatic sample tray and the first liquid inlet arm to the initial position, and the small aircraft ascending into the air to collect samples at different altitudes; during sampling, the sample gas enters a dual-channel micro spiral trap and mixes with the absorption liquid entering the dual-channel micro spiral trap. The sample solution is formed by contact with the sampler. Driven by the first inlet arm, the sample solution is injected into the storage bottle through the first inlet needle. The sampling process is repeated at different altitudes to collect sample gas at different altitudes. When the small aircraft lands, the automatic sample tray in the automatic sampler is removed and placed in the automatic reaction detector. The colorimetric solution is automatically injected into the storage bottle on the sample tray in sequence by the second inlet arm, and reacts with the sample solution to be tested to produce a colorimetric reaction. The constant temperature reaction vessel keeps the reaction temperature constant. After the reaction is completed, the sample solution to be tested is passed into the absorption cell in the same order by the suction arm, and the component concentration is detected by the detector.

[0015] Furthermore, if nitrite is being tested, the temperature of the sample solution in the storage bottle during the reaction is controlled at 50°C in the constant-temperature reactor; if formaldehyde is being tested, the temperature of the sample solution in the storage bottle during the reaction is controlled at 70°C in the constant-temperature reactor.

[0016] Furthermore, the detector performs component concentration detection as follows: the concentration of the analyte in the sample solution is obtained according to Beer-Lambert's law; the gas phase concentration of the analyte is obtained by inversion based on the sampling volume and the absorption liquid volume; the concentration of the analyte in the sample solution at different spatial locations is measured to obtain the profile data of the analyte.

[0017] The present invention has the following advantages due to the adoption of the above technical solutions: 1. This invention achieves lightweight design. Through micro-quantification of the solution and automated system control, the system can be integrated into two small and lightweight parts, enabling the sampling and detection of gaseous pollutants such as HONO and HCHO mounted on a small aircraft. The micro-sampling component weighs approximately 7.5 kg, making it lightweight and suitable for integration with other atmospheric environmental monitoring devices on a small aircraft.

[0018] 2. This invention employs a dual-channel wet chemical detection method with low detection limits and high accuracy, capable of measuring trace amounts of HONO and HCHO in ambient air.

[0019] 3. This invention has strong scalability and high flexibility. It can detect the vertical or horizontal profiles of HONO and HCHO, and the micro-sampling section can also be used for high-altitude sample collection of water-soluble components such as NO2, SO2, NH4, HCl, and HNO3, enabling flexible measurement of various pollutants.

[0020] 4. This invention enables on-site measurement. The detection component uses long-path spectrophotometry, which is highly portable and can be transported to the site. After the sample is collected and landed, it can be derivatized and measured on-site without returning to the laboratory. After the sample lands, the entire process of adding liquid, reaction, injection, and detection is completed within 1 hour, allowing for rapid and accurate data acquisition.

[0021] 5. This invention enables the coordinated operation of sample collection and detection. It facilitates rapid sample transfer, significantly improving assembly efficiency before sampling, sample storage efficiency during sampling, and transfer and reaction detection efficiency after sampling. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the micro-sampling section in the detection device of this embodiment of the invention; Figure 2 This is a schematic diagram of the rapid detection section in the detection device according to an embodiment of the present invention; Figure label: 100—Automatic sampler, 110—Sample gas collector, 120—Automatic sample storage container, 111—Absorbent liquid storage bottle, 112—Dual-channel micro-volume spiral trap, 113—Peristaltic pump, 114—Gas flow meter, 115—First three-way valve, 116—Safety bottle, 117—Gas pump, 118—Waste liquid pump, 119—Waste liquid pool, 121—Automatic sample tray, 122—Storage bottle, 123—First inlet needle, 124—First inlet arm, 125—First turntable, 126—First geared stepper motor; 200—Rapid detector, 210—Automatic reaction injector, 211—Color development solution storage bottle, 212—Second turntable, 213—Second geared stepper motor, 214—Second injection needle, 215—Second injection arm, 216—Aspiration needle, 217—Aspiration arm, 218—Second stepper motor, 219—Third stepper motor, 2110—Constant temperature reaction vessel, 220—Detection mechanism, 221—Defoamer, 222—Absorption cell, 223—Detector. Detailed Implementation

[0023] To address the technical problems mentioned above, this invention provides a detection device and method for detecting trace HONO and HCHO profiles in the atmosphere, applicable to small aircraft. Based on wet chemical detection and automatic control technologies, it achieves lightweight, trace-level (ppt-level), automated, portable, and real-time detection. This invention also provides a dual-channel automatic sample holder for automatically storing multiple sets of trace samples, and an automatic reaction detector for automatically adding liquid, conducting isothermal heating reactions, and automatically injecting trace samples. The dual-channel automatic sample holder and the automatic reaction detector are equipped with identical automatic sample trays, enabling rapid sample transfer and quick switching and linkage between aerial sampling and ground detection.

[0024] The principle of this invention is as follows: the detection of trace HONO and HCHO profiles in the atmosphere is carried out in two steps: a sampling process using a micro-volume automatic sampler mounted on a small aircraft, and a rapid response and automatic detection process on the ground. During sampling, the micro-volume sampler, mounted on the small aircraft, ascends into the air. The sample gas comes into full contact with the HONO or HCHO absorbent in a dual-channel micro-spiral trap, where the HONO or HCHO is captured and forms the test solution. This test solution flows into a storage vial in an automatic sample tray under the action of a peristaltic pump and an automatic liquid inlet rod. The automatic sample tray position and the automatic liquid inlet rod are automatically switched at different altitudes or locations to store multiple samples for subsequent detection. While HONO has an absorption efficiency of over 99% in the absorbent in a single-channel spiral trap, it is easily interfered with by nitrogen oxides such as NO2 in the air. This invention employs a dual-channel micro-volume trap and dual long-path detection channels, allowing the concentration data obtained from the two channels to be subtracted to obtain the HONO concentration value after deducting interference. The HCHO collection efficiency in a single-channel spiral trap is 98%-99%. To obtain a higher HCHO collection efficiency, the concentration data measured in both channels are added together to obtain the HCHO concentration value.

[0025] After sampling, the small aircraft lands and removes the automated sample tray from the miniature sampler, placing it into the automated reaction detector on the ground. The automated reactor, containing a thermostatic reaction vessel (with a pre-set heating temperature based on the detected component, e.g., 50°C for HONO and 70°C for HCHO), provides a constant-temperature heating environment for the automated sample tray. The chromogenic solution is automatically added to the storage vial on the automated sample tray, and the reaction begins. The reacted sample is automatically injected into a long-path spectrophotometer for absorbance measurement to obtain the concentration of the analyte in the test solution. The concentration of the analyte in the air is then calculated based on the sampling volume and the volume of the absorber. Measuring the concentration of the analyte at different altitudes yields the profile data of the analyte.

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] Example 1: In this example, a device for detecting trace amounts of nitrous acid and formaldehyde in the atmosphere, carried by a small aircraft, is provided. In this example, as... Figure 1 , Figure 2 As shown, the detection device includes: An automatic sampler 100, mounted on a small aircraft, is used to collect trace amounts of HONO and HCHO in the atmosphere. The automatic sampler 100 includes a sample gas collector 110 and an automatic sample storage unit 120. The sample gas collector 110 includes an absorbent storage bottle 111 and a dual-channel micro-spiral trap 112. The absorbent in the absorbent storage bottle 111 is fed into the dual-channel micro-spiral trap 112 via a peristaltic pump 113. The sample gas enters the dual-channel micro-spiral trap 112 and mixes with the absorbent in the trap to form a sample solution. The automatic sample storage unit 120 includes an automatic sample tray 121. Multiple pairs of storage bottles 122 are arranged at 21 circumferential intervals. An automatic sample tray 121 is placed on a first turntable 125 and is driven to rotate automatically by a first reduction stepper motor 126 mounted on the first turntable. A pair of first injection needles 123 are arranged above the automatic sample tray 121. The top of each first injection needle 123 is connected to the two outlets of a dual-channel micro spiral trap 112 through a tube. The first injection needle 123 is driven up and down by a first injection arm 124 to inject the sample solution into the storage bottle 122. The programmed up and down movement of the first injection needles and the rotation of the automatic sample tray enable the automatic storage of multiple sets of samples into different storage bottles.

[0029] A rapid reaction detector 200 is installed on the ground and includes an automatic reaction injector 210 and a detection mechanism 220. The detection mechanism 220 includes a defoamer 221 and an absorption cell 222. The automatic reaction injector 210 includes a colorimetric solution storage bottle 211 and an automatic sample tray 121, with the automatic sample tray 121 placed on a second turntable 212. The second turntable 212 is automatically rotated by a second reduction stepper motor 213 mounted on it, and is placed in a constant-temperature reaction vessel 2110. A pair of second injection needles 214 are positioned above the second turntable, through which the colorimetric solution in the colorimetric solution storage bottle 211 is injected into the automatic sample tray 121 to complete the sample solution collection. Within cell 22, a sample solution is formed; the second injection needle 214 is driven up and down by the second injection arm 215, and the program of the second injection needle moving up and down and the automatic sample tray rotating is used to automatically inject the colorimetric solution into different storage bottles; the sample solution is extracted into the absorption cell 222 through a pair of extraction needles 216, which are driven up and down by the extraction arm 217, and the program of the extraction needle moving up and down and the automatic sample tray rotating is used to automatically inject different groups of sample solutions into the absorption cell; the absorption cell 222 is connected to a detector 223, which detects the component concentration of the sample solution.

[0030] In the above embodiments, such as Figure 2 As shown, in addition to the absorbent storage bottle 111, the dual-channel micro-spiral trap 112, and the peristaltic pump 113, the sample gas collector 110 also includes a liquid flow meter, a gas flow meter 114, a first three-way valve 115, a safety bottle 116, a vacuum pump 117, a waste liquid pump 118, and a waste liquid pool 119.

[0031] The absorbent storage bottle 111 is connected to the inlet of a liquid flow meter via a solution pipeline. The outlet of the liquid flow meter is connected to the inlet of a first three-way valve 115, and the solution volume is monitored and controlled by the liquid flow meter. The two outlets of the first three-way valve 115 are respectively connected to the first and second channel inlets of the dual-channel micro-spiral trap 112. The vent of the dual-channel micro-spiral trap 112 is connected to the vent of a safety bottle 116, through which abnormal accumulated liquid is discharged. The first and second channel outlets of the dual-channel micro-spiral trap 112 are respectively connected to the corresponding first inlet needle 123 via solution pipelines.

[0032] In this embodiment, the peristaltic pump 113 is a four-channel peristaltic pump. The first channel of the four-channel peristaltic pump 113 is connected to the first tee and the first channel inlet of the dual-channel micro-spiral trap 112. The second channel of the four-channel peristaltic pump 113 is connected to the first tee and the second channel inlet of the dual-channel micro-spiral trap 112. The third channel of the four-channel peristaltic pump 113 is connected to the first channel outlet of the dual-channel micro-spiral trap 112 and the inlet of the first inlet needle 123 of the inlet arm. The fourth channel of the four-channel peristaltic pump 113 is connected to the second channel outlet of the dual-channel micro-spiral trap 112 and the inlet of the second inlet needle 123 of the inlet arm.

[0033] In this embodiment, the dual-channel micro-spiral trap 112 is used for gas-liquid mixing, trapping the analyte in the sample gas into the absorption liquid to form the sample. The outlet of the dual-channel micro-spiral trap 112 is connected to a safety bottle 116. The upper exhaust port of the safety bottle 116 is connected in sequence to a gas flow meter 114 and a vacuum pump 117 to discharge waste gas. The bottom liquid outlet of the safety bottle 116 is connected to a waste liquid pool 119 via a waste liquid pump 118, which pumps the waste liquid into the waste liquid pool 119.

[0034] A gas flow meter 114 is installed at the outlet of the safety bottle 116; the inlet of the gas flow meter 114 is connected to the outlet of the safety bottle 116, and the outlet of the gas flow meter 114 is connected to the suction port of the suction pump 117. The gas flow meter 114 is used to control the sampling flow rate.

[0035] In the above embodiment, the automatic sample storage device 120 is used to automatically switch and store multiple sets of samples. One end of the first liquid inlet arm 124 is provided with a first liquid inlet needle clamping hole, and the other end of the first liquid inlet arm 124 is connected to a first lead screw, which is connected to a first stepper motor. The first stepper motor drives the first lead screw to rotate, thereby controlling the up-and-down movement of the first liquid inlet arm 124. The automatic sample tray 121 is mounted on the first tray 125, and the first reduction stepper motor 126 drives the first tray 125 and the automatic sample tray 121 to rotate automatically.

[0036] Specifically, the automatic sample tray 121 is controlled to rotate by a first reduction stepper motor 126. The first reduction stepper motor 126 is started and stopped, and 10 stop positions are set, corresponding to 10 liquid storage vials. The automatic sample tray 121 rotates at a constant speed of 0.05 rpm, meaning it takes 2 seconds to rotate from one stop position to the next. The first liquid inlet arm 124 is controlled to move up and down by the first stepper motor, and has two positions: one where the first liquid inlet arm 124 is raised to the waiting position, and the first liquid inlet needle 123 leaves the automatic sample tray 121 without affecting its rotation; the other where the first liquid inlet arm 124 is lowered to the liquid inlet position, and the first liquid inlet needle 123 is inserted under the cap of the liquid storage bottle 122. The rotation speed of the first stepper motor is constant, designed to complete the lifting in 1 second and the lowering in 2 seconds.

[0037] The positional relationship between the automatic sample tray 121 and the first liquid inlet arm 124 is as follows: (1) When the machine starts running, the first liquid inlet arm 124 is raised, the automatic sample tray 121 is placed in the initial position, the first set of liquid storage bottles 122 is located directly opposite the first liquid inlet needle 123, and the first liquid inlet needle 123 moves down to the liquid inlet position to start liquid inlet; (2) After the first set of liquid inlet is completed, the first liquid inlet needle 123 moves up to the waiting position, the automatic sample tray 121 rotates to the second stop position and stops, the second set of liquid storage bottles 122 is located directly opposite the first liquid inlet needle 123, and the first liquid inlet needle 123 moves down to the liquid inlet position to start liquid inlet, and so on. This process is automated by pre-setting a program.

[0038] In this embodiment, the automatic sample tray 121 is equipped with two sets of storage bottles 122, which are located on the inner and outer rings of the automatic sample tray 121, respectively; each set can contain 10 storage bottles 122, with a maximum storage capacity of 8 ml. The first channel outlet of the dual-channel micro spiral trap 112 is connected to the inlet end above the first inlet needle, and the second channel outlet is connected to the inlet end of the second inlet needle. The outlet end of the first inlet needle is aligned with the cap of the outer ring storage bottle placed on the automatic sample tray 121, and the outlet end of the second inlet needle is aligned with the cap of the storage bottle 122 placed on the inner ring of the automatic sample tray 121.

[0039] In the above embodiments, such as Figure 2As shown, the automatic reaction sampler 210 is used to automatically inject the colorimetric solution into the storage bottle 122 and heat it to promote color development. Specifically: a constant-temperature reaction vessel 2110 surrounds the automatic sample tray 121 and maintains its temperature at a set level; one end of the second injection arm 215 is provided with a second injection needle clamping hole, and the other end of the second injection arm 215 is connected to a second lead screw, which is connected to a second stepper motor 218. One end of the suction arm 217 is provided with a suction needle clamping hole, and the other end of the suction arm 217 is connected to a third lead screw, which is connected to a third stepper motor 219. In use, the second stepper motor 218 drives the second lead screw to rotate, controlling the movement of the second injection arm 215; the third stepper motor 219 drives the third lead screw to rotate, controlling the movement of the suction arm 217. The automatic sample tray 121 is mounted on the second tray 212, and the second reduction stepper motor 213 drives the second turntable 212 and the automatic sample tray 121 to rotate automatically.

[0040] Specifically, the rotational speeds of the second stepper motor 218 and the third stepper motor 219 are the same as those of the first stepper motor 126. The motion relationship between the automatic sample tray 121, the second liquid inlet arm 215, and the liquid extraction arm 217 is consistent with the relationship between the automatic sample tray 121 and the first liquid inlet arm 124, which will not be elaborated here.

[0041] In the above embodiment, there are two absorption cells 222, both of which are long-path colorimetric cells; and a light source is provided outside each long-path colorimetric cell.

[0042] like Figure 2 As shown, the detection mechanism 220 also includes a second three-way valve and a defoamer 221. The colorimetric solution storage bottle 211 is connected via the second three-way valve to the inlet ports of a pair of second inlet needles 214 on the second inlet arm 215. The outlet ports of the pair of second inlet needles 214 are respectively aligned with the caps of the storage bottles 122 on the outer and inner rings of the automatic sample tray 121. The inlet ports of a pair of suction needles 216 on the suction arm 217 are aligned with the caps of the storage bottles 122 on the outer and inner rings of the automatic sample tray 121. The outlet ports of the pair of suction needles 216 are respectively connected to the inlet of a defoamer 221, and the outlet ports of the defoamer 221 are respectively connected to the inlet ports of the absorption cell 222. The light source 224 is connected to the light inlet port of the absorption cell 222 via an optical fiber, and the detector 223 is connected to the light outlet port of the absorption cell 222 via an optical fiber.

[0043] In this embodiment, a two-channel peristaltic pump is provided at the inlet of the second inlet needle 214. The first and second channels of the two-channel peristaltic pump are connected to the second tee and a pair of second inlet needles 214. A four-channel peristaltic pump is provided at the outlet of the suction needle 216. The first channel of the four-channel peristaltic pump is connected to the outlet of a suction needle and a defoamer 221, the second channel is connected to the outlet of another suction needle and another defoamer 221, the third channel is connected to the outlet of a defoamer 221 to a detector 222, and the fourth channel is connected to the outlet of another defoamer 221 to another detector 222.

[0044] In the above embodiments, both the first turntable 125 and the second turntable 212 are made of carbon fiber material to effectively reduce weight. The cap of the liquid storage bottle 122 is a silicone cap to facilitate the insertion of the automatic liquid inlet needle and the automatic liquid extraction needle into the bottle. The first liquid inlet arm 124 and the second liquid inlet arm 215 have two positions, namely the liquid inlet position and the switching position, and the liquid extraction arm 217 has two positions, namely the liquid extraction position and the switching position.

[0045] In summary, when using this invention, all samples are placed in the storage bottle 122 and integrated on the automatic sample tray 121. The automatic sample tray 121 is adapted to the automatic sampler 100 of the micro-sampling section and the rapid response detector 200 of the rapid detection section. After sampling, the sample can be quickly transferred from the micro-sampling section to the rapid detection section along with the automatic sample tray 121.

[0046] In the micro-sampling section, during sampling, a vacuum diaphragm pump is used to extract sample gas, which is then introduced into the dual-channel micro-volume spiral trap 112. Simultaneously, a 1 / 16” PTFE tube and a peristaltic pump tube are used to introduce the absorbent liquid from the absorbent liquid storage bottle 111 into the dual-channel micro-volume spiral trap 112. The resulting first-channel test liquid is introduced through the peristaltic pump tube into a first inlet needle on a first inlet arm. This first inlet needle pierces under the cap of the storage bottle 122 on the outer ring of the automatic sample tray 121, allowing the first-channel test liquid to enter the storage bottle 122. In step 22, the obtained test liquid in the second channel is introduced into another first inlet needle on another first inlet arm through a peristaltic pump tube. This first inlet needle pierces the cap of the storage bottle 122 on the inner ring of the automatic sample tray 121, allowing the test liquid in the second channel to enter the storage bottle 122. When the test sample is injected into the storage bottle 122, the first inlet arm is in the inlet position. After one test sample is injected, when switching to the next test sample, the first inlet arm is raised, and the automatic sample tray 121 rotates until the inlet needle is aligned with the next set of storage bottles 122.

[0047] In the detection section, the colorimetric solution enters the inlet needle of the second inlet arm simultaneously through the second three-way valve. The inlet needle is inserted into the storage bottle 122 on the automatic sample tray 121, and the colorimetric reaction begins after the colorimetric solution is injected into the storage bottle 122. A constant-temperature reactor outside the automatic sample tray 121 maintains constant temperature control of the test solution during the reaction. After the reaction is complete, the suction arm switches to the suction position, and the suction needle is inserted into the storage bottle 122. The test sample from one channel after the reaction is drawn in by one suction needle on the suction arm, sent to the corresponding defoamer for defoaming, and then enters the inlet of the first long-path colorimetric cell. Simultaneously, light emitted from the first light source enters the light inlet of the first long-path colorimetric cell. After being absorbed by the test solution in the first channel after the reaction, the light from the first light source enters the first detector through the light outlet of the first long-path colorimetric cell to detect the light intensity and calculate the liquid phase concentration of the analyte in the test sample of the first channel. The detection method for the test sample in the second channel is the same as that for the first channel, and then the gas phase concentration of the analyte is calculated.

[0048] Example 2 provides a method for detecting trace nitrite and formaldehyde profiles in the atmosphere, applicable to small aircraft. This method is based on the detection devices described in the above examples. In this example, the detection method includes the following steps: 1) Prepare the absorption solution and the color development solution.

[0049] 2) Sampling: The automatic sampler is mounted on a small aircraft, the liquid storage bottle is placed in the automatic sample tray, the automatic sample tray and the first liquid inlet arm are adjusted to the initial position, the small aircraft ascends into the air, and samples are collected at different altitudes; during sampling, the sample gas enters the dual-channel micro spiral trap 112 and mixes with the absorbent liquid entering the dual-channel micro spiral trap 112 to form a sample solution; driven by the first liquid inlet arm, the sample solution is injected into the liquid storage bottle through the first liquid inlet needle; the sampling process is repeated at different altitudes to complete the collection of sample gas at different altitudes.

[0050] Specifically, based on actual sampling needs, the sample loading time and sampling flow rate are designed, the absorption liquid is prepared and placed in the absorption liquid bottle, and the 8ml storage vial is placed into the automatic sample tray; the sample tray and the first liquid inlet arm are adjusted to the initial position; the micro-sampling part is mounted on a small aircraft.

[0051] A micro-sampler is mounted on a small aircraft and ascends into the air to collect samples at different altitudes. During sampling, the sample gas enters a dual-channel micro-spiral trap, first entering the first channel and then the second channel. Simultaneously, the absorbent enters both channels in parallel. The analyte comes into full contact with the corresponding absorbent and is then captured, forming the analyte solution. This analyte solution flows into the inlet needle under the action of a peristaltic pump. The inlet needle, driven by the inlet arm, inserts into a sample storage vial in the automated sample tray. The analyte solution flows into the storage vial. Each sample collection process takes 3-5 minutes, yielding two samples captured by the first and second channel traps: the first-channel analyte solution and the second-channel analyte solution. Each sample volume is 1-1.5 ml. The fully automated sample tray contains two sets of sample storage vials for storing the analyte samples. The first-channel analyte solution is injected into the first set of vials, and the second-channel analyte solution is injected into the second set of vials. The automatic rotation of the sample tray and the up-and-down movement of the inlet needle driven by the first inlet arm allow multiple sets of samples to be stored in different vials at different positions on the automatic sample tray. During sampling, air samples are collected at different altitudes or positions by controlling the arrival time of the small aircraft at different altitudes or positions and the sampling time of the automatic sampler.

[0052] 3) Detection: After the small aircraft lands, the automatic sample tray from the automatic sampler is removed and placed in the automatic reaction detector. The colorimetric solution is automatically injected into the storage bottle 122 on the sample tray under the action of the second liquid inlet arm, and a colorimetric reaction occurs with the sample solution to be tested. The constant temperature reaction vessel keeps the reaction temperature constant. After the reaction is completed, the sample solution to be tested is passed into the absorption cell in the same order under the action of the liquid extraction arm, and the detector detects the component concentration. The concentration of the component to be tested in the sample solution is obtained according to the Lambert-Beer law. The gas phase concentration of the component to be tested is obtained by inversion based on the sampling volume and the absorption liquid volume. The concentration of the component to be tested in the sample solution at different altitudes is measured to obtain the profile data of the component to be tested.

[0053] In step 3) above, the corresponding detection program is set in advance according to the type of pollutant to be detected. For example, for HONO detection, the temperature of the constant temperature reactor is set to 50℃ and the reaction residence time (the time between the injection of the reaction liquid into the storage bottle 122 and the extraction of the solution after the reaction for detection) is 3 minutes; for HCHO detection, the temperature of the constant temperature reactor is set to 70℃ and the reaction residence time is 5 minutes.

[0054] Specifically, after sampling, the small aircraft lands and removes the automatic sample tray from the micro-sampler, placing it in the fully automated reaction and injection unit for rapid detection. The fully automated reaction and injection unit includes a thermostatic reactor to maintain the temperature of the automatic sample tray. During detection, the chromogenic solution is automatically injected sequentially into the sample storage vial on the automatic sample tray by a peristaltic pump and a second inlet arm, reacting with the sample to produce a colorimetric reaction. The injection volume of the chromogenic solution is 1-1.5 ml. After the reaction is complete, the sample is then passed through a long-path spectrophotometer in the same order by a peristaltic pump and a suction arm for automatic absorbance detection. The concentration of the analyte in the sample is obtained according to Beer-Lambert's law, and the gas phase concentration of the analyte is obtained by inversion based on the sampling volume and the volume of the absorption liquid.

[0055] In step 3) above, the concentration values ​​of a series of samples measured by one channel are recorded as follows: C 1,i Where i is the sample sampling number. The concentration of the series of samples measured by the two channels is... C 2,i .

[0056] If the detected component is HONO, then C HONO Let i be the HONO concentration of the i-th sample group: C HONO , i = C 1, i - C 2, i If the detected component is HCHO, then C HCHO , i The HCHO concentration of the i-th sample is: C HCHO , i = C 1, i + C 2, i Measuring the concentration of the analyte in samples at different spatial locations yields the profile data of the analyte.

[0057] The invention is further described through embodiments, but the scope of the invention is not limited in any way. The method and apparatus provided by this invention for detecting trace HONO and HCHO profiles in the atmosphere for use on small aircraft are used to measure the HONO profile in the atmosphere.

[0058] Step 1: Weigh 12ml of hydrochloric acid and 1g of sulfanilamide, dissolve them in pure water and bring the volume to 1L to prepare an absorption solution. Mix them evenly and place them in an absorption solution bottle. Weigh 0.1g of naphthylethylenediamine hydrochloride, dissolve it in pure water and bring the volume to 1L to prepare a colorimetric solution.

[0059] Step 2: During sampling, adjust the first liquid inlet arm and the automatic sample tray of the micro sampling part to the initial position, that is, the first liquid inlet arm is in the switching position, the liquid inlet is aligned with the first group of liquid storage bottles of the automatic sample tray and loaded into the small aircraft, and the micro sampling part is loaded into the small aircraft.

[0060] Step 3: The small aircraft begins collecting the first set of samples. At this time, the sample gas, driven by a vacuum diaphragm pump, is introduced into the dual-channel spiral trap at a flow rate of 0.5 L / min. Simultaneously, the absorbent liquid, driven by the first and second channels of a four-channel peristaltic pump, is introduced into the inlets of the first and second channels of the spiral trap at a flow rate of 0.3 ml / min, forming a liquid film. HONO in the sample gas diffuses into the absorbent liquid and reacts with sulfonamides in the absorbent liquid to generate diazo compounds, forming the analyte. The first inlet arm switches to the inlet position, and the analyte is injected into the first set of storage vials in the automatic sample tray.

[0061] Step 4: After the first set of samples is collected for 3 minutes, the four-channel peristaltic pump stops running, the first inlet arm is raised, the automatic sample tray is switched to the inlet needle and aimed at the second set of storage vials, the small aircraft ascends to 50 meters above the ground and hovers for 3 minutes to collect the second set of samples. Then, it ascends 50 meters and hovers for 3 minutes to collect the next set of samples, until the 10th set of samples is collected at an altitude of 450 meters. After that, the small aircraft returns to the ground.

[0062] Step 5: During testing, remove the automatic sample tray from the micro-sampling section and place it into the constant-temperature reactor of the rapid reaction and detection section. The constant-temperature reactor is pre-set to 50℃. The automatic sample tray moves to the inlet on the second inlet arm, aligning it with the first group of sample storage vials. The second inlet arm moves from the switching position to the inlet position, and the two-channel peristaltic pump starts, injecting the colorimetric solution into the first group of samples to begin the reaction. After injecting 1ml of colorimetric solution, the two-channel peristaltic pump pauses, the second inlet arm moves to the switching position, the automatic sample tray switches to the inlet, aligning it with the second group of samples, and the two-channel peristaltic pump starts, injecting the colorimetric solution into the second group of samples. The injection of colorimetric solution is carried out at a uniform rate, with a 3-minute interval between each sample. Then, colorimetric solution is injected into samples 3-10 sequentially.

[0063] Step 6: After all samples have been injected with the colorimetric solution, the automatic sample tray is switched to the suction arm and the suction needle is aimed at the first sample storage vial. Samples are then drawn into the long-path absorption cell at the same interval (3 min) as when the colorimetric solution is added to detect the HONO concentration.

[0064] Step 7: Calculate the HONO concentration of all samples according to the formula.

[0065] Step 8: Obtain the HONO profile in the atmosphere at the testing location based on the HONO concentration values ​​at different altitudes.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for detecting atmospheric trace nitrite and formaldehyde profiles on small aircraft, characterized in that, include: An automatic sampler, mounted on a small aircraft, includes a sample gas collector and an automatic sample storage device; The sample gas collector includes an absorbent storage bottle and a dual-channel micro-spiral trap. The absorbent in the absorbent storage bottle is pumped into the dual-channel micro-spiral trap by a peristaltic pump. The sample gas enters the dual-channel micro-spiral trap and mixes with the absorbent in the trap to form a sample solution. The automatic sample holder includes an automatic sample tray with multiple pairs of storage bottles spaced around its circumference. The automatic sample tray is placed on a first turntable and rotates automatically via a first reduction stepper motor mounted on the turntable. Above the automatic sample tray is a pair of first inlet needles. The top of each needle is connected to two outlets of the dual-channel micro-spiral trap via a tubing. The needles are moved up and down by a first inlet arm to inject the sample solution into the storage bottle. The rapid reaction detector is set on the ground and includes an automatic reaction injector and a detection mechanism. The detection mechanism includes a defoamer and an absorption cell. The automatic reaction injector includes a colorimetric solution storage bottle and an automatic sample tray placed on a second turntable. It is driven to rotate automatically by a second reduction stepper motor mounted on the second turntable. The second turntable is placed in a constant temperature reaction vessel. A pair of second injection needles are located above the second turntable. The colorimetric solution in the colorimetric solution storage bottle is injected into the storage bottle on the automatic sample tray to complete the sample solution collection, forming the sample solution to be tested. The second injection needles are driven up and down by the second injection arm. The sample solution to be tested is extracted into the absorption cell through a pair of extraction needles, which are driven up and down by the extraction arm. The absorption cell is connected to a detector, which detects the component concentration of the sample solution to be tested.

2. The detection device for atmospheric trace nitrite and formaldehyde profiles applied to small aircraft as described in claim 1, characterized in that, The sample gas collector also includes a liquid flow meter, a first three-way valve, and a safety bottle; The absorbent storage bottle is connected to the inlet of a liquid flow meter via a solution pipeline. The outlet of the liquid flow meter is connected to the inlet of the first three-way valve. The liquid flow meter monitors and controls the solution volume. The two outlets of the first three-way valve are connected to the first and second channel inlets of the dual-channel micro-spiral trap, respectively. The outlet of the dual-channel micro-spiral trap is connected to the inlet of a safety bottle. Abnormal liquid accumulation is discharged through the safety bottle. The first and second channel outlets of the dual-channel micro-spiral trap are connected to the corresponding first inlet needles via solution pipelines.

3. The detection device for atmospheric trace nitrite and formaldehyde profiles applied to small aircraft as described in claim 2, characterized in that, The peristaltic pump is a four-channel peristaltic pump; the first channel of the four-channel peristaltic pump is connected to the first tee and the first channel inlet of the dual-channel micro-spiral trap; the second channel of the four-channel peristaltic pump is connected to the first tee and the second channel inlet of the dual-channel micro-spiral trap; the third channel of the four-channel peristaltic pump is connected to the first channel outlet of the dual-channel micro-spiral trap and the inlet of the first inlet needle of the inlet arm; and the fourth channel of the four-channel peristaltic pump is connected to the second channel outlet of the dual-channel micro-spiral trap and the inlet of the second inlet needle of the inlet arm.

4. The detection device for atmospheric trace nitrite and formaldehyde profiles applied to small aircraft as described in claim 2, characterized in that, The outlet of the dual-channel micro-spiral trap is connected to a safety bottle. The upper exhaust port of the safety bottle is connected to a gas flow meter and a gas pump in sequence. The bottom liquid outlet of the safety bottle is connected to a waste liquid pool via a waste liquid pump, which pumps the waste liquid into the waste liquid pool. A gas flow meter is installed at the outlet of the safety bottle.

5. The detection device for atmospheric trace nitrite and formaldehyde profiles applied to small aircraft as described in claim 1, characterized in that, One end of the first liquid inlet arm is provided with a first liquid inlet needle clamping hole, and the other end of the first liquid inlet arm is connected to a first lead screw. The first lead screw is connected to a first stepper motor, and the first stepper motor drives the first lead screw to rotate in order to control the first liquid inlet arm.

6. The detection device for atmospheric trace nitrite and formaldehyde profiles applied to small aircraft as described in claim 1, characterized in that, One end of the second inlet arm is provided with a second inlet needle clamping hole, and the other end of the second inlet arm is connected to a second lead screw, which is connected to a second stepper motor; one end of the suction arm is provided with a suction needle clamping hole, and the other end of the suction arm is connected to a third lead screw, which is connected to a third stepper motor.

7. The detection device for atmospheric trace nitrite and formaldehyde profiles applied to small aircraft as described in claim 1, characterized in that, Two absorption cells are provided, both of which are long-path colorimetric cells; and a light source is provided outside each long-path colorimetric cell. The testing mechanism also includes a second three-way valve and a defoamer; the colorimetric solution storage bottle is connected to the inlet of a pair of second inlet needles on the second inlet arm via the second three-way valve, and the outlet of the pair of second inlet needles is respectively aligned with the caps of the storage bottles on the outer and inner rings of the automatic sample tray; the inlet of a pair of suction needles on the suction arm is aligned with the caps of the storage bottles on the outer and inner rings of the automatic sample tray; the outlet of the pair of suction needles is respectively connected to the inlet of a defoamer, and the outlet of the defoamer is respectively connected to the inlet of the absorption cell; the light source is connected to the light inlet of the absorption cell via an optical fiber, and the detector is connected to the light outlet of the absorption cell via an optical fiber.

8. A method for detecting atmospheric trace nitrite and formaldehyde profiles on a small aircraft, implemented based on the detection device for atmospheric trace nitrite and formaldehyde profiles on a small aircraft as described in any one of claims 1 to 7, characterized in that, include: Prepare the absorption solution and the colorimetric solution; An automatic sampler is mounted on a small aircraft. The storage bottle is placed in the automatic sample tray. The automatic sample tray and the first liquid inlet arm are adjusted to their initial positions. The small aircraft ascends into the air to collect samples at different altitudes. During sampling, the sample gas enters a dual-channel micro spiral trap and mixes with the absorbent liquid entering the trap to form a sample solution. Driven by the first liquid inlet arm, the sample solution is injected into the storage bottle through the first liquid inlet needle. The sampling process is repeated at different altitudes to complete the collection of sample gas at different altitudes. The small aircraft lands, removes the automatic sample tray from the automatic sampler, and places it in the automatic reaction detector. The colorimetric solution is automatically injected into the storage bottle on the sample tray under the action of the second inlet arm, and reacts with the sample solution to be tested to produce a colorimetric reaction. The constant temperature reaction vessel keeps the reaction temperature constant. After the reaction is complete, the sample solution to be tested is passed into the absorption cell in the same order under the action of the pumping arm, and the component concentration is detected by the detector.

9. The method for detecting atmospheric trace nitrite and formaldehyde profiles on small aircraft as described in claim 8, characterized in that, If testing for nitrite, the temperature of the sample solution in the storage bottle during the reaction is controlled at 50℃ in the constant temperature reactor; if testing for formaldehyde, the temperature of the sample solution in the storage bottle during the reaction is controlled at 70℃ in the constant temperature reactor.

10. The method for detecting atmospheric trace nitrite and formaldehyde profiles on a small aircraft as described in claim 8, characterized in that, The detector performs component concentration detection as follows: the concentration of the analyte in the sample solution is obtained according to Beer-Lambert's law; the gas phase concentration of the analyte is obtained by inversion based on the sampling volume and the absorption liquid volume; the concentration of the analyte in the sample solution at different spatial locations is measured to obtain the profile data of the analyte.

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