A gaseous nitrous acid sampler for high frequency isotope analysis and a working method thereof

Abstract

The invention discloses a gaseous nitrous acid sampler and a working method for high-frequency isotope analysis, and relates to the technical field of analytical measurement devices. The sampler comprises a left dual-channel sampling tube and a right dual-channel sampling tube with the same structure. The left dual-channel sampling tube comprises a first channel and a second channel arranged from bottom to top, an air inlet is arranged at the bottom of the first channel, and an air outlet is arranged at the top of the second channel. Coating rings are arranged in the first channel and the second channel. The upper parts of the first channel and the second channel are connected to corresponding flushing liquid tanks, coating liquid tanks and nitrogen bottles, and the lower parts of the first channel and the second channel are connected to corresponding waste liquid bottles and collection trays. The invention can meet the needs of efficient and accurate collection of atmospheric HONO samples, and ensure that the sample concentration is sufficient for high-precision isotope analysis, thereby providing stronger technical support for analyzing the source, generation mechanism and atmospheric chemical behavior of HONO.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and measurement devices, and in particular to a gaseous nitrous acid sampler for high-frequency isotope analysis and a working method thereof. Background Art

[0002] Gaseous nitrous acid (HONO) is a key active substance in the atmosphere. Its photolysis produces hydroxyl radicals (·OH), which aggravates air pollution and the frequency of haze. The sources and formation mechanisms of HONO in the atmosphere are very complex and involve multiple pathways. However, factors such as the lack of field observations, the uncertainty of emission factors, and the lack of emission inventories have led to considerable controversy in current research on the sources and formation mechanisms of HONO. In recent years, with the increasing demand for accurate quantification of the sources of atmospheric HONO, stable isotope technology has shown a rapid development trend in tracing the sources of atmospheric HONO. As a high-precision analytical method, this technology can effectively distinguish HONO from different sources and formation paths by utilizing the differences in the isotopic composition of HONO emitted by different types of sources.

[0003] When conducting isotope analysis, HONO samples need to be collected offline first. The commonly used sampling method is the dissolver sampling method recommended by the US Environmental Protection Agency (EPA). This method usually requires a long sampling time (several hours to several days) and is difficult to provide data with high time resolution. In addition, the dissolver method also relies on a lot of manual operations, including the preparation of absorption liquid, sample processing and analysis, and the process is complicated and time-consuming. Because it involves liquid sample processing, there is a risk of sample contamination, especially in field sampling. In addition to the dissolver method, the existing wet chemical method can achieve high-frequency measurement of HONO and provide concentration data with higher time resolution, but it usually cannot reach the concentration standard required for isotope analysis, and the absorption liquid is difficult to recover for subsequent isotope determination. This leads to a technical gap between high-frequency acquisition and isotope analysis, which limits the in-depth study of HONO. It can be seen that although the existing isotope analysis methods have strong advantages in analyzing the source and formation of HONO, they are limited by low-frequency acquisition and analysis and cannot fully and dynamically reveal the generation and transformation process of HONO. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a gaseous nitrous acid sampler and a working method for high-frequency isotope analysis, which can meet the needs of efficient and accurate collection of atmospheric HONO samples, while ensuring that the sample concentration is sufficient for high-precision isotope analysis, thereby providing stronger technical support for analyzing the source, generation mechanism and atmospheric chemical behavior of HONO.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect of the present invention, a gaseous nitrite sampler for high-frequency isotope analysis is provided, comprising a left dual-channel sampling tube and a right dual-channel sampling tube of the same structure, the left dual-channel sampling tube comprising a first channel and a second channel which are interconnected and arranged from bottom to top, an air inlet is arranged at the bottom of the first channel, an air outlet is arranged at the top of the second channel, coating rings are arranged in the first channel and the second channel, the upper parts of the first channel and the second channel are connected to corresponding flushing liquid tanks, coating liquid tanks and nitrogen bottles, and the lower parts of the first channel and the second channel are connected to corresponding waste liquid bottles and collection trays.

[0007] In some embodiments of the present invention, the right dual-channel sampling tube includes a third channel and a fourth channel arranged from bottom to top, an air inlet is arranged at the bottom of the third channel, an air outlet is arranged at the top of the fourth channel, and coating rings are arranged in the third channel and the fourth channel; the upper parts of the third channel and the fourth channel are connected to the corresponding flushing liquid tank, coating liquid tank and nitrogen bottle, the lower part of the third channel is connected to the waste liquid bottle and the collecting tray connected to the first channel, and the lower part of the fourth channel is connected to the waste liquid bottle and the collecting tray connected to the second channel; wherein, the difference between the concentration and isotope detection results of the sample obtained from the collecting tray connected to the first channel and the third channel and the sample obtained from the collecting tray connected to the second channel and the fourth channel is the content and isotope abundance characteristics of gaseous nitrous acid in the gas to be tested.

[0008] In some embodiments of the present invention, the coating ring is made of Teflon material, connected to the inner wall surface of the sampling channel by an adhesive, and sealed at the connection by a sealing strip; the coating ring is a circular cavity structure, the annular body is a liquid storage chamber, and an upper coating ring and a lower coating ring are provided in each channel, wherein the bottom of the upper coating ring is provided with evenly distributed liquid injection holes, and the top of the lower coating ring is provided with evenly distributed liquid collection holes.

[0009] In some embodiments of the present invention, the liquid storage chamber in the upper coating ring is connected to the coating liquid tank and the flushing liquid tank through a pipe, the coating liquid tank and the flushing liquid tank are arranged in parallel, and peristaltic pumps are provided on the outlet pipe of the coating liquid tank and the outlet pipe of the flushing liquid tank; the liquid storage chamber in the lower coating ring is connected to the waste liquid bottle through a pipe.

[0010] In some embodiments of the present invention, the coating liquid tank contains a coating liquid, and the coating liquid is a mixture of carbonate buffer and phosphate buffer, which are mixed in a ratio of 1:1, and the pH value of the mixture is 7-9.

[0011] In some embodiments of the present invention, a flushing liquid is placed in the flushing liquid tank, and the flushing liquid is ultrapure water. The flushing liquid enters the channel through the coating ring to clean the coating ring and the channel.

[0012] In some embodiments of the present invention, filter membranes are provided at the air inlets at the bottom of the first channel and the third channel.

[0013] In some embodiments of the present invention, a plurality of sample collection bottles are arranged on the collection tray, and the plurality of sample collection bottles are distributed in the circumferential direction of the collection tray. The collection tray can drive the sample collection bottles to rotate, and the collection tray is placed in a constant temperature system.

[0014] In a second aspect of the present invention, there is provided a method for operating a gaseous nitrous acid sampler for high frequency isotope analysis, comprising:

[0015] The coating liquid in the coating liquid tank enters the coating rings of the first channel, the second channel, the third channel and the fourth channel respectively, and continuously flows downward under the influence of gravity, so that the liquid spreads all over the inner wall surface of the channel. After the coating liquid flows out of the channel, it flows into the waste liquid bottle through the peristaltic pump, realizing the automatic coating function;

[0016] The nitrogen in the nitrogen bottle enters the first channel, the second channel, the third channel and the fourth channel respectively, and blows the coating liquid in the channel dry, thus realizing the automatic blowing function;

[0017] The gas to be tested enters the first channel and the third channel from the gas inlet, reacts with the coating liquid in the first channel and the third channel, and then enters the second channel and the fourth channel, reacts with the coating liquid in the second channel and the fourth channel, and the coating liquid absorbs HONO in the gas to be tested;

[0018] The flushing liquid in the flushing liquid tank enters the first channel, the second channel, the third channel and the fourth channel respectively, flushes the reaction liquid on the coating ring in each channel, and then flows into the sample collection bottle on the collection plate for collection;

[0019] After sampling is completed, concentration analysis and detection are performed on the samples obtained from the collection plate connected to the first channel and the third channel and the samples obtained from the collection plate connected to the second channel and the fourth channel, and the difference in the detection results is the content of gaseous nitrous acid in the gas to be tested; isotope analysis and detection are performed respectively, and the difference in the detection results is the isotope abundance characteristic of the gaseous nitrous acid in the gas to be tested.

[0020] One or more technical solutions of the present invention have the following beneficial effects:

[0021] (1) The present invention uses a mixture of carbonate buffer and phosphate buffer as the absorption liquid to replace the traditional sodium carbonate-glycerol-methanol mixed absorption liquid. The new absorption liquid can control the pH value that is too high. The multiphase reaction can avoid the low collection efficiency of HONO caused by too low pH. It will significantly improve the capture capacity of atmospheric HONO and have a faster adsorption rate, thus being able to meet the needs of large-flow gas sampling.

[0022] (2) The present invention can realize automatic replacement of coating liquid, and has functions such as automatic coating, drying, and rinsing. Through precise program control, it ensures seamless connection and efficient execution of each step. The visual operation interface is designed to make the status and operation process of each functional module clear at a glance, and allow users to set parameters and operation procedures according to specific needs. The development of this system will significantly reduce human pollution, the complexity and errors of manual operation, and improve the efficiency and reliability of the sampling process.

[0023] (3) The present invention adopts an advanced roulette sample collector. After the sample collection is completed, the flushing liquid flows into the coating ring and flows downward evenly by gravity. The collected HONO is brought into the No. 1 sample collection bottle through the peristaltic pump. Before that, the required sample volume is set. After the collection is completed, the No. 1 sample collection bottle rotates counterclockwise to the position of the No. 12 sample collection bottle, and the No. 2 sample collection bottle moves to the arrow-indicated area (i.e., the original No. 1 sample collection bottle position), and so on, to prepare for the next sample collection. The high-frequency collection system is constructed through the above process. In order to ensure the integrity and stability of the collected samples, a precision temperature control room is specially set up to preserve the samples collected at high frequency, to maximize the storage of samples under optimal conditions, thereby improving the accuracy and reliability of subsequent analysis.

[0024] (4) The present invention is realized by the design of a dual-channel sampling tube, which greatly improves the sampling efficiency, thereby effectively increasing the sampling volume of HONO. At present, due to the high sample quantity requirements of HONO isotope analysis, the existing technology usually needs to extend the sampling time to meet the requirements. The present invention significantly improves the HONO sampling volume per unit time by adding sampling channels, which not only meets the needs of conventional HONO isotope analysis, but also provides technical support for the realization of high-frequency HONO isotope observations. This innovative design shortens the time required for sampling, makes high-temporal and spatial resolution HONO isotope research possible, and provides important support for in-depth research in the field of atmospheric chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the gaseous nitrous acid sampler for high-frequency isotope analysis of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of the channel and the coating ring of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of the sample collection plate of the present invention;

[0028] Figure 4 is a cross-sectional view of a coating ring of the present invention;

[0029] Figure 5 The above are the test data of the absorption effect of the absorption liquid of the present invention.

[0030] In the figure: 1, first channel; 2, second channel; 3, third channel; 4, fourth channel; 5, flushing liquid tank; 6, filter membrane; 7, coating ring; 701, liquid storage chamber; 702, liquid injection hole or liquid collection hole; 703, groove; 704, sealing strip; 8, waste liquid bottle; 9, coating liquid tank; 10, peristaltic pump; 11, collection plate; 12, air valve; 13, nitrogen bottle; 14, sample collection bottle. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] Example 1

[0033] In a typical embodiment of the present invention, a gaseous nitrous acid sampler for high-frequency isotope analysis is provided, such as Figure 1-Figure 3 As shown, it includes a left dual-channel sampling tube and a right dual-channel sampling tube with the same structure, the left dual-channel sampling tube includes a first channel 1 and a second channel 2 which are interconnected and arranged from bottom to top, an air inlet is arranged at the bottom of the first channel 1, and an air outlet is arranged at the top of the second channel 2, a coating ring 7 is arranged in the first channel 1 and the second channel 2, the upper parts of the first channel 1 and the second channel 2 are connected to the corresponding flushing liquid tank 5, the coating liquid tank 9 and the nitrogen bottle 13, and the lower parts of the first channel and the second channel are connected to the corresponding waste liquid bottle and the collecting tray 11.

[0034] In this embodiment, the structure of the right dual-channel sampling tube is the same as that of the left dual-channel sampling tube. The right dual-channel sampling tube includes a third channel 3 and a fourth channel 4 arranged from bottom to top, an air inlet is arranged at the bottom of the third channel 3, and an air outlet is arranged at the top of the fourth channel 4, and a coating ring 7 is arranged in the third channel and the fourth channel; the upper parts of the third channel and the fourth channel are connected to the corresponding flushing liquid tank, coating liquid tank and nitrogen bottle, the lower part of the third channel 3 is connected to the waste liquid bottle 8 and the collecting tray 11 connected to the first channel 1, and the lower part of the fourth channel 4 is connected to the waste liquid bottle and the collecting tray connected to the second channel 2; wherein, the difference between the concentration and isotope detection result of the sample obtained by the collecting tray connected to the first channel 1 and the third channel 3 and the sample obtained by the collecting tray connected to the second channel 2 and the fourth channel 4 is the content of gaseous nitrous acid in the gas to be tested and the isotope abundance characteristics.

[0035] like Figure 4As shown, the coating ring 7 is made of Teflon material and connected to the inner wall of the sampling channel through an adhesive. The groove 703 on the coating ring 7 can match the protrusion on the inner wall of the channel, and the high-performance sealing strip 704 is used to seal at the connection to ensure the air tightness and operation stability of the entire device; the coating ring is a circular cavity structure, the annular body is a liquid storage chamber 701, and the coating ring is provided with a liquid injection hole or a liquid receiving hole 702, and the liquid injection hole or the liquid receiving hole 702 is connected to the liquid storage chamber 701. An upper coating ring and a lower coating ring are provided in each channel, wherein the bottom of the upper coating ring is provided with evenly distributed liquid injection holes, and the top of the lower coating ring is provided with evenly distributed liquid receiving holes. These injection holes have a small diameter, which can make the flow rate of the absorption liquid much lower than the initial flow rate when it enters the liquid storage chamber. With the help of gravity, the absorption liquid can be distributed to the inner wall of the absorption channel in a relatively uniform manner to form a stable coating layer, thereby improving the absorption efficiency and avoiding sampling deviations that may be caused by uneven liquid flow. The excess absorption liquid enters the lower coating ring storage chamber through the liquid receiving hole and is finally discharged into the waste liquid bottle.

[0036] Furthermore, the liquid storage chamber in the upper coating ring is connected to the coating liquid tank and the flushing liquid tank through a pipe, the coating liquid tank and the flushing liquid tank are arranged in parallel, and peristaltic pumps are provided on the outlet pipe of the coating liquid tank and the outlet pipe of the flushing liquid tank; the liquid storage chamber in the lower coating ring is connected to the waste liquid bottle through a pipe.

[0037] In this embodiment, the coating liquid tank 9 contains a coating liquid, which is a mixture of carbonate buffer and phosphate buffer, which are mixed in a ratio of 1:1, and the pH value of the mixture is 7-9, so as to replace the traditional sodium carbonate-glycerol-methanol mixed absorption liquid. The absorption liquid can absorb HONO in the atmosphere and generate , collect the absorption liquid that has absorbed HONO, and measure the The concentration of HONO in the atmosphere can be obtained by measuring the concentration of HONO in the atmosphere. The multi-phase reaction can avoid the low collection efficiency of HONO caused by too low pH. It will significantly improve the capture capacity of atmospheric HONO and have a faster adsorption rate, so as to meet the needs of large-flow gas sampling; increase the number of sampling channels, and upgrade the traditional single-channel sampling tube design to a multi-channel sampling tube. This multi-channel structure will significantly increase the absorption of HONO, and establish an enrichment module by integrating multiple sampling tubes, so as to effectively enrich HONO samples with sufficient concentration in a short time (within 1 hour).

[0038] In addition, a mixture of carbonate buffer and phosphate buffer was used as the coating solution. After absorbing HONO, in addition to HONO concentration detection, isotope analysis can also be performed. The absorption efficiency of the absorption solution was systematically verified by setting 5 different HONO concentration gradients (0.1 ppb, 0.5 ppb, 2 ppb, 5 ppb, 10 ppb). The results are as follows: Figure 5 The correlation coefficient of the data fitting result is r=0.999, indicating that the absorption liquid designed by the patent has a very high absorption efficiency for HONO. In addition, the absorption liquid can fix the absorbed HONO into nitrite, providing a reliable sample basis for subsequent isotope analysis, thereby expanding its application potential in atmospheric chemistry research.

[0039] In this embodiment, a rinse liquid is placed in the rinse liquid tank. The rinse liquid is ultrapure water. The rinse liquid enters the channel through the coating ring to clean the coating ring and the channel.

[0040] In this embodiment, a filter membrane 6 is provided at the air inlet at the bottom of the first channel 1 and the third channel 3, and the filter membrane can achieve physical interception of particulate matter in the gas entering the channel, and can block the particulate matter in the air. and , preventing them from entering the sampling system, thereby avoiding their interference with the HONO measurement results after dissolving in the absorption liquid; Gas selective filtration: Some filter membranes (such as specific coatings or materials) have the function of selectively excluding specific gases, which can weaken The possibility of entering the system, thereby further reducing interference.

[0041] In this embodiment, the sampling channels are all made of glass, and the design ensures the consistency of the gas channels. At the same time, the absorption liquid is evenly coated on each channel through an independent upper coating ring. This independent coating method avoids cross-interference of liquids and ensures the efficiency and accuracy of the absorption process. The excess absorption liquid is efficiently collected by the respective lower coating rings and directed to the waste liquid bottle, further optimizing the system's operating procedures and the convenience of waste liquid treatment.

[0042] Furthermore, each channel is connected to an independent flushing liquid tank, coating liquid tank and nitrogen bottle respectively, instead of sharing the same device, mainly to ensure the independence of the sampling process and the efficient operation of the system. It has the following advantages: each channel is independently connected to the relevant device, which can effectively avoid the mixing of flushing liquid, coating liquid or airflow between different channels, thereby ensuring the purity of the sampling conditions of each channel; the independent nitrogen bottle enables the airflow pressure and flow rate of each channel to be controlled separately, thereby achieving more accurate sampling and coating effects; sharing a device may cause the failure of a certain channel to affect the operation of the entire system, while the independent device design can limit the problem to a single channel, reduce interference with other channels, and improve the stability and reliability of the system; independent equipment makes the experimental conditions and parameters of each channel more consistent, which helps to obtain truly comparable results between channels without introducing additional errors due to uneven distribution of liquid or gas flow.

[0043] In this embodiment, a plurality of sample collection bottles are arranged on the collection tray, and the plurality of sample collection bottles are distributed in the circumferential direction of the collection tray. The collection tray can drive the sample collection bottles to rotate. The collection tray is placed in a constant temperature system. Temperature changes may cause changes in the physical and chemical properties of the HONO sample. By placing the sample in a constant temperature environment (about -18°C), the uncertainty caused by temperature fluctuations can be eliminated, thereby ensuring the repeatability and reliability of the experimental results. Figure 3 The top view of the collection plate is shown. When the sample collection is completed, the flushing liquid flows into the coating ring and flows downward evenly by gravity, and the collected HONO is brought into the No. 1 sample collection bottle through the peristaltic pump. Before that, the required sample volume is set. After the collection is completed, stop, and the No. 1 sample collection bottle rotates counterclockwise to the position of the No. 12 sample collection bottle, and the No. 2 sample collection bottle to the arrow-indicated area (i.e. the original No. 1 sample collection bottle position), and so on, to prepare for the next sample collection. The high-frequency collection system is constructed through the above process. In order to ensure the integrity and stability of the collected samples, a precision temperature control room is specially set up to preserve the samples collected at high frequency, to maximize the storage of samples under optimal conditions, and thus improve the accuracy and reliability of subsequent analysis.

[0044] In this embodiment, the nitrogen bottle is connected to the channel through an air valve, and the nitrogen enters the channel to dry the coating liquid on the coating ring. The purpose of drying the coating liquid is mainly to remove excess solvent and ensure the uniform distribution of the coating liquid in the absorption channel, thereby improving the absorption efficiency. Nitrogen is inert under most conditions and will not react with the components in the coating liquid. Therefore, it can be safely used in the drying process without interfering with the absorption characteristics of the coating liquid or affecting the accuracy of the experimental data. Nitrogen itself does not contain moisture and will not introduce additional moisture to avoid affecting the drying process of the coating liquid. At the same time, it will not introduce other substances that may affect the absorption process. The coating liquid has lost its solvent component after drying, and it can still effectively absorb HONO. This is because even after the coating liquid is dried, the chemical components in the absorption liquid can still maintain their adsorption characteristics. In addition, as air flows into the system, the moisture in the air interacts with the coating liquid, further promoting the absorption of HONO.

[0045] The system will have the functions of automatic coating, blowing, rinsing, etc. The coating liquid stored in the coating liquid tank 9 can be evenly introduced into the coating rings of the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 through the peristaltic pump 10, and continuously flow downward under the influence of gravity, so that the liquid spreads over the inner wall of the sampling channel. After the coating liquid flows out of the sampling tube, it flows into the waste liquid bottle 8 through the peristaltic pump to realize the automatic coating function; the nitrogen in the nitrogen bottle 13 enters the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 through the air valve 12 to blow dry the coating liquid in the sampling tube to realize the automatic blowing function; the flushing liquid stored in the flushing liquid tank can be evenly introduced into the coating rings of the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 through the peristaltic pump 10 to rinse the sampling channel in preparation for the next sampling. After the flushing liquid flows out of the sampling tube, it flows into the waste liquid bottle 8 through the peristaltic pump to realize the automatic flushing function. Through precise program control, the seamless connection and efficient execution of each step are ensured. The visual operation interface is designed to make the status and operation process of each functional module clear at a glance, and allow users to set parameters and operation processes according to specific needs. The development of this system will significantly reduce human pollution, the complexity and errors of manual operation, and improve the efficiency and reliability of the sampling process.

[0046] The working process of the gaseous nitrous acid sampler for high-frequency isotope analysis provided in this embodiment is as follows:

[0047] The coating liquid is placed in a coating liquid tank 9, and the coating liquid is uniformly introduced into the coating rings of the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 respectively through a peristaltic pump 10, and continuously flows downward under the influence of gravity, so that the liquid spreads over the inner wall surface of the channel. The coating liquid is a mixture of carbonate buffer and phosphate buffer. After the coating liquid flows out of the sampling tube, it flows into the waste liquid bottle 8 through a peristaltic pump;

[0048] The nitrogen in the nitrogen bottle 13 enters the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 through the gas valve 12 to dry the coating liquid in the sampling tube;

[0049] The gas to be tested enters the first channel 1 and the third channel 3 from the air inlet through the filter membrane 6, reacts with the coating liquid in the first channel and the third channel, and then enters the second channel 2 and the fourth channel 4, reacts with the coating liquid in the second channel and the fourth channel, and the coating liquid can absorb HONO in the atmosphere;

[0050] The flushing liquid is placed in the flushing liquid tank 5, and the flushing liquid is uniformly introduced into the coating rings of the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 respectively through the peristaltic pump 10. The flushing liquid is ultrapure water. The flushing liquid flushes the reaction liquid of the gas to be tested and the coating liquid of the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4, and then flows into the sample collection bottle 14 in the constant temperature system through the peristaltic pump. The sample collection bottle is placed on a collection tray 11. After the sample collection is completed, the collection tray can rotate the next empty sample collection bottle to the outflow of the flushing liquid to prepare for the next sample collection;

[0051] After the sample collection is completed, the flushing liquid is evenly introduced into the coating rings of the first channel 1, the second channel 2, the third channel 3, and the fourth channel 4 through the peristaltic pump 10 to rinse the sampling tube in preparation for the next sampling. After the flushing liquid flows out of the sampling tube, it flows into the waste liquid bottle 8 through the peristaltic pump;

[0052] The difference between the sample test results collected by the first three channels and the sample test results collected by the second four channels is the HONO content and isotope abundance characteristics in the atmosphere. During the sampling process, the first and third channels can completely absorb the HONO in the atmosphere and absorb .because The concentration is very high and It is the main interference that affects HONO concentration and isotope analysis. To interfere with the results, the second and fourth channels are connected in series above the first and third channels. The distribution in the four channels is homogenized. With this configuration, the concentration of HONO can be accurately determined by calculating the concentration difference between the two channels in series, effectively eliminating The impact on HONO measurement ensures the accuracy of measurement and the reliability of isotope analysis.

[0053] For all the above processes, users can set parameters and operation procedures according to specific needs on the visual operation interface; and the data acquisition and transmission system can record the key parameters of the sampling process (such as sampling time, temperature, humidity, air flow rate, etc.) in real time, and can transmit the data to the terminal device via the wireless network.

[0054] The gaseous nitrite sampler provided in this embodiment has a sample volume sufficient to meet the needs of HONO concentration and isotope analysis each time. In addition, the system design allows the user to flexibly set the collection time according to the experimental requirements, such as collecting once an hour. Each time sampling, the series channels on the left and right sides will be sampled at the same time to ensure synchronization and data consistency. After completing one hour of sampling, the instrument will automatically perform pretreatment steps such as rinsing, coating, and drying to prepare for the next hour of sampling. The sample collection process is carried out according to preset time periods. This design not only improves the efficiency of sampling, but also ensures the quality and comparability of samples in each time period.

[0055] The "next sampling" mentioned in the working process of this embodiment refers to collecting air samples from the same fixed location, and the main difference is the different time periods of sampling. During repeated experiments and sampling, the source of the gas sample remains consistent, and the only variable is the specific time period of collection. This design can effectively track and analyze the changes in gas concentration in different time periods, thereby providing a more comprehensive understanding and trend analysis of the temporal and spatial changes in air quality.

[0056] The gaseous nitrite sampler provided in this embodiment is realized by the design of a dual-channel sampling tube, which greatly improves the sampling efficiency, thereby effectively increasing the sampling volume of HONO. At present, due to the high requirements of HONO isotope analysis on the sample quantity, the existing technology usually needs to extend the sampling time to meet the demand. However, this embodiment significantly improves the HONO sampling volume per unit time by increasing the sampling channel, which can not only meet the needs of conventional HONO isotope analysis, but also provide technical guarantee for realizing high-frequency HONO isotope observations. This innovative design shortens the time required for sampling, makes high-temporal and spatial resolution HONO isotope research possible, and provides important support for in-depth research in the field of atmospheric chemistry.

[0057] Example 2

[0058] In a typical embodiment of the present invention, a working method of a gaseous nitrous acid sampler for high-frequency isotope analysis is provided, comprising:

[0059] The coating liquid in the coating liquid tank enters the coating rings of the first channel, the second channel, the third channel and the fourth channel respectively, and continuously flows downward under the influence of gravity, so that the liquid spreads all over the inner wall surface of the channel. After the coating liquid flows out of the sampling tube, it flows into the waste liquid bottle through the peristaltic pump, realizing the automatic coating function;

[0060] The nitrogen in the nitrogen bottle enters the first channel, the second channel, the third channel and the fourth channel respectively, and blows the coating liquid in the channel dry, thus realizing the automatic blowing function;

[0061] The gas to be tested enters the first channel and the third channel from the gas inlet, reacts with the coating liquid in the first channel and the third channel, and then enters the second channel and the fourth channel, reacts with the coating liquid in the second channel and the fourth channel, and the coating liquid absorbs HONO in the gas to be tested;

[0062] The flushing liquid in the flushing liquid tank enters the first channel, the second channel, the third channel and the fourth channel respectively, flushes the reaction liquid on the coating ring in each channel, and then flows into the sample collection bottle on the collection plate for collection;

[0063] After sampling is completed, concentration analysis and detection are performed on the samples obtained from the collection plate connected to the first channel and the third channel and the samples obtained from the collection plate connected to the second channel and the fourth channel, and the difference in the detection results is the content of gaseous nitrous acid in the gas to be tested; isotope analysis and detection are performed respectively, and the difference in the detection results is the isotope abundance characteristic of the gaseous nitrous acid in the gas to be tested.

[0064] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A gaseous nitrous acid sampler for high frequency isotope analysis, characterized in that: It comprises a left dual-channel sampling tube and a right dual-channel sampling tube with the same structure, the left dual-channel sampling tube comprises a first channel and a second channel which are interconnected and arranged from bottom to top, an air inlet is arranged at the bottom of the first channel, and an air outlet is arranged at the top of the second channel, an upper coating ring and a lower coating ring are arranged in the first channel and the second channel, the upper coating rings of the first channel and the second channel are connected to corresponding flushing liquid tanks, coating liquid tanks and nitrogen bottles, and the lower coating rings of the first channel and the second channel are connected to corresponding waste liquid bottles and collection trays.

2. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 1, characterized in that: The right dual-channel sampling tube includes a third channel and a fourth channel arranged from bottom to top, an air inlet is arranged at the bottom of the third channel, and an air outlet is arranged at the top of the fourth channel, and an upper coating ring and a lower coating ring are arranged in the third channel and the fourth channel; the upper coating rings of the third channel and the fourth channel are connected to the corresponding flushing liquid tank, coating liquid tank and nitrogen bottle, the lower coating ring of the third channel is connected to the waste liquid bottle and the collecting plate connected to the first channel, and the lower coating ring of the fourth channel is connected to the waste liquid bottle and the collecting plate connected to the second channel; wherein, the difference between the concentration and isotope detection result of the sample obtained from the collecting plate connected to the first channel and the third channel and the sample obtained from the collecting plate connected to the second channel and the fourth channel is the content of gaseous nitrous acid in the gas to be tested and the isotope abundance characteristics.

3. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 2, characterized in that: The upper coating ring and the lower coating ring are made of Teflon material, connected to the inner wall surface of the sampling channel by adhesive, and sealed at the connection by a sealing strip; the upper coating ring and the lower coating ring are annular cavity structures, the annular body is a liquid storage chamber, and an upper coating ring and a lower coating ring are arranged in each channel, wherein the bottom of the upper coating ring is provided with evenly distributed liquid injection holes, and the top of the lower coating ring is provided with evenly distributed liquid collection holes.

4. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 3, characterized in that: The liquid storage chamber in the upper coating ring is connected to the coating liquid tank and the flushing liquid tank through a pipeline. The coating liquid tank and the flushing liquid tank are arranged in parallel. Peristaltic pumps are arranged on the outlet pipes of the coating liquid tank and the outlet pipes of the flushing liquid tank; the liquid storage chamber in the lower coating ring is connected to the waste liquid bottle through a pipeline.

5. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 4, characterized in that: The coating liquid tank contains a coating liquid, which is a mixture of carbonate buffer and phosphate buffer, which are mixed in a ratio of 1:1, and the pH value of the mixture is 7-9.

6. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 4, characterized in that: The flushing liquid tank contains flushing liquid, which is ultrapure water. The flushing liquid enters the channel through the upper coating ring to clean the upper coating ring, the lower coating ring and the channel.

7. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 2, characterized in that: Filter membranes are provided at the air inlets at the bottom of the first channel and the third channel.

8. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 1, characterized in that: A plurality of sample collecting bottles are arranged on the collecting tray, and the plurality of sample collecting bottles are distributed in the circumferential direction of the collecting tray. The collecting tray can drive the sample collecting bottles to rotate, and the collecting tray is placed in a constant temperature system.

9. The gaseous nitrous acid sampler for high-frequency isotope analysis according to claim 1, characterized in that: The nitrogen bottle is connected to the channel through a gas valve, and the nitrogen gas dries the coating liquid in the channel after entering the channel.

10. A method for operating a gaseous nitrous acid sampler for high-frequency isotope analysis according to any one of claims 2 to 7, characterized in that: include: The coating liquid in the coating liquid tank enters the upper coating rings of the first channel, the second channel, the third channel and the fourth channel respectively, and continuously flows downward under the influence of gravity, so that the liquid spreads over the inner wall surface of the channel. After the coating liquid flows out of the channel, it flows into the waste liquid bottle through the peristaltic pump, realizing the automatic coating function; The nitrogen in the nitrogen bottle enters the first channel, the second channel, the third channel and the fourth channel respectively, and blows the coating liquid in the channel dry, thus realizing the automatic blowing function; The gas to be tested enters the first channel and the third channel from the gas inlet, reacts with the coating liquid in the first channel and the third channel, and then enters the second channel and the fourth channel, reacts with the coating liquid in the second channel and the fourth channel, and the coating liquid absorbs HONO in the gas to be tested; The flushing liquid in the flushing liquid tank enters the first channel, the second channel, the third channel and the fourth channel respectively, flushes the reaction liquid on the upper coating ring and the lower coating ring in each channel, and then flows into the sample collection bottle on the collection plate for collection; After sampling is completed, concentration analysis and detection are performed on the samples obtained from the collection plate connected to the first channel and the third channel and the samples obtained from the collection plate connected to the second channel and the fourth channel, and the difference in the detection results is the content of gaseous nitrous acid in the gas to be tested; isotope analysis and detection are performed respectively, and the difference in the detection results is the isotope abundance characteristic of the gaseous nitrous acid in the gas to be tested.

Images