A liquid core waveguide in-situ online multi-component high-sensitivity detection system

Abstract

The utility model discloses a liquid core waveguide in-situ online multi-component high-sensitivity detection system, which is used for on-site online detection of aqueous solutions, including a liquid core waveguide tube made of Teflon AF material, a flow path structure, a detection structure and a degassing structure. The flow path structure is used to inject the aqueous solution to be detected into the liquid core waveguide tube, and the detection structure uses a photometric method to detect the aqueous solution in the liquid core waveguide. The liquid core waveguide tube uses the air-permeable and water-impermeable characteristics of the Teflon AF material, combined with the degassing structure to remove bubbles in the aqueous solution in the liquid core waveguide tube, thereby improving the quality of the detection structure for in-situ online detection of multiple components of the aqueous solution. The utility model improves the sensitivity and accuracy of the detection of trace components of the aqueous solution through the total internal reflection characteristics of the liquid core waveguide tube and the negative pressure pumping method, so that the optical signal that was previously difficult to detect can be easily detected.

Description

Technical Field

[0001] The utility model relates to the field of detection and analysis technology, in particular to a liquid core waveguide in-situ online multi-component high-sensitivity detection system. Background Art

[0002] Polluted water poses a major threat to the environment and human health, and real-time acquisition of water quality information is an effective way to achieve water pollution control. Among them, the online in-situ detection of trace components in aqueous solutions is the first step in obtaining water quality information. Therefore, it is of great significance to achieve in-situ online detection of multiple components in aqueous solutions. At present, the detection of aqueous solution components in my country is mostly based on regular sampling combined with laboratory chemical analysis. The sampling method is mainly manual sampling, which has high labor costs, high resource investment, and long time. Therefore, a liquid core waveguide in-situ online multi-component high-sensitivity detection system is urgently needed. Utility Model Content

[0003] In order to solve the above technical problems, the utility model provides a liquid core waveguide in-situ online multi-component high-sensitivity detection system.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0005] A liquid core waveguide in-situ online multi-component high-sensitivity detection system, comprising a liquid core waveguide tube made of Teflon AF material, a flow path structure, a detection structure and a degassing structure;

[0006] The degassing structure includes a degassing tube, a liquid core waveguide runs through the degassing tube, and a sealed cavity is formed between the liquid core waveguide and the sealed cavity, a vacuum pump is connected through a pipeline, and a tee is provided at both ends of the liquid core waveguide, one end of the tee is used as a port for light to pass through and is sealed by a quartz light window, and the other end is used as a port for detection liquid to pass through;

[0007] A light emitting diode and a photodetector are arranged near both ends of the liquid core waveguide, a three-way pipe is located at one end of the quartz light window, and optical fibers are arranged through flanges in a direction away from the liquid core waveguide, a collimator is arranged at the end of the optical fiber, and the quartz light window, the light emitting diode, the photodetector, the optical fiber, the collimator and the liquid core waveguide are all in the same straight line to form a detection structure;

[0008] One of the three-way pipes is connected to a drain pipe on the port for the detection liquid to pass through, and the other three-way pipe is connected to a multi-position switching valve on the port for the detection liquid to pass through a pipeline. The multi-position switching valve is also respectively connected to a test liquid injection pipe and a color developer injection pipe, and a drain valve is provided on the drain pipe to form a flow path structure.

[0009] Preferably, the multi-position switching valve is also connected to an air extraction pipe, and the air extraction pipe is connected to an air extraction pump.

[0010] Preferably, a liquid injection valve is provided on the pipeline, and a sample mixing pool is also provided at a position between the multi-position switching valve and the liquid discharge valve.

[0011] Preferably, a waste liquid storage tank is provided at the discharge end of the discharge pipe.

[0012] Preferably, the multi-position switching valve is also connected to a gas-liquid injection pipe.

[0013] Preferably, the drain pipe and the pipeline are both made of polytetrafluoroethylene.

[0014] Preferably, the above also includes a controller for controlling the operating status of a multi-position switching valve, a drain valve, a light-emitting diode, a vacuum pump and an air extraction pump, and a processor connected to a photoelectric detector. Both the controller and the processor are connected to the terminal device through a wireless communication module, and the terminal device includes a computer, a mobile phone and a tablet.

[0015] Compared with the prior art, the utility model has the following beneficial effects:

[0016] 1. The utility model improves the sensitivity and accuracy of detecting trace components in aqueous solutions through the total internal reflection characteristics of the liquid core waveguide and the negative pressure pumping method, making it easy to detect optical signals that were previously difficult to detect.

[0017] 2. By using photodetectors and light-emitting diodes, the cost of the instrument is reduced and the size of the instrument is reduced. Through overall integration and modular design, the needs of on-site in-situ detection and long-term dynamic monitoring are met.

[0018] 3. The controller controls the operating status of the multi-position switching valve, drain valve, light-emitting diode, vacuum pump and air pump to achieve full automation of the liquid inlet, waste discharge and cleaning process. At the same time, the wireless communication module is used to transmit the collected data to the terminal device in real time to achieve dynamic detection without human intervention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the utility model.

[0020] Figure symbols: 1. Liquid core waveguide tube, 20. Liquid injection valve, 21. Liquid discharge pipe, 22. Pipeline, 23. Multi-position switching valve, 24. Test liquid injection pipe, 25. Color developer injection pipe, 26. Liquid discharge valve, 27. Vacuum pipe, 28. Sample mixing pool, 29. Gas-liquid injection pipe, 31. Light-emitting diode, 32. Photoelectric detector, 33. Optical fiber, 34. Collimating mirror, 41. Degassing tube, 42. Sealed chamber, 43. Vacuum pump, 5. Tee pipe, 6. Quartz light window, 7. Flange, 8. Waste liquid storage tank. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the utility model more clearly understood, the utility model is further described in detail below in conjunction with embodiments and drawings. The schematic implementation manner of the utility model and its description are only used to explain the utility model and are not intended to limit the utility model.

[0022] Example 1

[0023] like Figure 1 A liquid core waveguide in-situ online multi-component high-sensitivity detection system is shown, which is used for online detection of aqueous solutions, including a liquid core waveguide tube 1 made of Teflon AF material, as well as a flow path structure, a detection structure and a degassing structure. The Teflon AF material has the characteristics of being air-permeable and water-tight. As a prior art, it will not be described in detail here. The flow path structure is used to inject the aqueous solution to be detected into the liquid core waveguide tube 1, and the detection structure uses photometry to detect the aqueous solution in the liquid core waveguide tube 1. The liquid core waveguide tube 1 of this scheme uses the air-permeable and water-tight characteristics of the Teflon AF material, combined with the degassing structure to remove bubbles in the aqueous solution in the liquid core waveguide tube 1, thereby improving the quality of the detection structure for in-situ online detection of multiple components of the aqueous solution.

[0024] Specifically, the degassing structure includes a degassing tube 41, a liquid core waveguide tube 1 passes through the degassing tube 41, and a sealed cavity 42 is formed between the liquid core waveguide tube 1, and a vacuum pump 43 is connected to the sealed cavity through a pipeline. A tee 5 is provided at both ends of the liquid core waveguide tube 1, one end of the tee 5 is used as a port for light to pass through, and is sealed by a quartz light window 6, and the other end is used as a port for the detection liquid to pass through. The air in the degassing tube 41 is extracted by the vacuum pump 43, so that a negative pressure is formed in the sealed cavity 42, and then the air-permeable and water-tight characteristics of the liquid core waveguide tube 1 are utilized to remove the bubbles in the aqueous solution in the liquid core waveguide tube 1;

[0025] A light emitting diode 31 and a photodetector 32 are arranged near the two ends of the liquid core waveguide 1, respectively. The three-way pipe 5 is located at one end of the quartz light window 6, and an optical fiber 33 is arranged through a flange 7 in a direction away from the liquid core waveguide 1. A collimator 34 is provided at the end of the optical fiber 33, and the quartz light window 6, the light emitting diode 31, the photodetector 32, the optical fiber 33, the collimator 34 and the liquid core waveguide 1 are all in the same straight line to form a detection structure. In some embodiments, the light emitting diode 31 can be replaced by a halogen tungsten lamp, and the photodetector 32 can be replaced by a spectrometer;

[0026] One of the three-way tubes 5 is connected to a drain pipe 21 at the port for the detection liquid to pass through, and the other three-way tube 5 is connected to a multi-position switching valve 23 through a pipeline 22 at the port for the detection liquid to pass through. The multi-position switching valve 23 is also respectively connected to a test liquid injection pipe 24 and a color developer injection pipe 25. A drain valve 26 is provided on the drain pipe 21 to form a flow path structure.

[0027] As a preferred solution of the above embodiment, the multi-position switching valve 23 is also connected to the exhaust pipe 27, and the exhaust pipe 27 is connected to the exhaust pump. Before the sample liquid and the color developer enter the liquid core waveguide tube 1, the multi-position switching valve 7 is controlled to connect the exhaust pipe 27 with the pipeline 22, and the drain valve 26 on the drain pipe 21 is closed. The exhaust pump is started to use the exhaust pipe 27 to form a negative pressure environment inside the liquid core waveguide tube 1, so that the sample can easily enter the liquid core waveguide tube 1 later.

[0028] As a preferred solution of the above embodiment, in order to improve the detection quality, a liquid injection valve 20 is provided on the pipeline 22, and a sample mixing pool 28 is also provided at the position between the multi-position switching valve 23 and the liquid injection valve 20. The sample liquid and the color developer are mixed through the sample mixing pool 28 and injected into the liquid core waveguide tube 1 after sufficient reaction to be detected by the detection structure.

[0029] As a preferred solution of the above embodiment, in order to collect the detection waste liquid and facilitate the subsequent harmless treatment, a waste liquid storage tank 8 is provided at the discharge end of the discharge pipe 21 .

[0030] As a preferred solution of the above embodiment, in order to facilitate the cleaning of the flow path structure, the multi-position switching valve 23 is also connected to a gas-liquid injection pipe 29 .

[0031] As a preferred solution of the above embodiment, the drain pipe 21 and the pipeline 22 are both made of polytetrafluoroethylene material.

[0032] As a preferred embodiment of the above embodiment, the above also includes a controller for controlling the operating status of the multi-position switching valve 23, the drain valve 26, the light-emitting diode 31, the vacuum pump 43 and the air pump, and a processor connected to the photodetector 32. The controller and the processor are respectively connected to the terminal device through a wireless communication module, and the terminal device includes a computer, a mobile phone and a tablet.

[0033] When testing aqueous solutions, the steps of generating negative pressure, introducing color developing solution, degassing, testing, discharging waste and cleaning are completed in this order. First, the vacuum pump is started, and the multi-position switching valve 23 connects the vacuum pipe 27 to the liquid core waveguide 1 through the pipeline 22. The drain valve 26 is in a closed state, so that a negative pressure environment is formed inside the liquid core waveguide 1, which can facilitate the entry of the sample liquid. At the same time, the vacuum pump 43 is started to form a negative pressure environment in the sealed cavity 42; then, by controlling the multi-position switching valve 23, the sample liquid and the color developer are respectively injected into the sample mixing tank 28 through the test liquid injection pipe 24 and the color developer injection pipe 25 from the pipeline 22, and then transported to fill the liquid core waveguide 1. At this time, the liquid core waveguide 1 is airtight. Due to its water-permeable property, the sealed cavity 42 in a negative pressure environment discharges the bubbles in the liquid core waveguide 1; then the light emitting diodes 31 are turned on in sequence, and the generated light travels from the light emitting diodes 31 to the photodetector 32, passes through the collimator 34 in sequence and enters the optical fiber 33, and then passes through the quartz light window 6 to enter the liquid core waveguide 1 and undergoes total internal reflection. The optical signal is enhanced during the movement, and then is coupled to the photodetector 32 through the quartz light window 6, the optical fiber 33 and the collimator 34 in sequence, and is converted into an electrical signal and transmitted to the processor. After calculation, the result is displayed on the terminal device.

[0034] After the signal acquisition is completed, the drain valve 26 is opened, and the waste liquid enters the waste liquid storage tank 24 through the drain pipe 21 through the liquid level difference. In some embodiments, a peristaltic pump is provided on the drain pipe 21 to pump out the waste liquid; then a cleaning operation is performed, including water washing and air washing. First, pure water enters the pipeline 22, the sample mixing tank 28 and the liquid core waveguide tube 1 in turn through the gas-liquid injection pipe 29, and is discharged through the drain pipe 21, and then the vacuum pump 43 is turned on, and air is passed into the flow path structure through the gas-liquid injection pipe 29 to discharge the residual liquid in the flow path structure to avoid affecting the next detection.

[0035] Application Example 1:

[0036] In agricultural production, the detection of soil nitrate nitrogen content is an important indicator of field nutrient management; however, excessive use of chemical fertilizers, pesticides and other chemical substances during agricultural production activities and unreasonable irrigation methods have caused agricultural non-point source nitrogen pollution. At the same time, nitrate nitrogen is not easily adsorbed by soil colloids and is easily soluble in water, which makes it very susceptible to farmland irrigation and precipitation and enters groundwater. Nitrates will be converted into nitrites in water and react with amino compounds in the human body to form carcinogenic nitrosamines, so the accurate determination of nitrate nitrogen in farmland soil leaching solutions is very important.

[0037] For this purpose, this example is used to determine the nitrate nitrogen in the farmland soil leaching solution. In this embodiment, a cadmium column reduction module is connected before the test liquid is injected into the tube 24. The reduction column can be a commercially available product or can be prepared by itself, including a U-shaped glass tube, copper-plated cadmium particles and a joint sealing ring. Refer to the national standard GB / T 42487-2023 "Determination of nitrate nitrogen, nitrite nitrogen and ammonium nitrogen in soil quality - Potassium chloride solution extraction flow analysis method" for the determination of nitrate nitrogen, prepare a nitrate solution of known concentration as the standard solution, and prepare the corresponding color developer. Figure 1 In the device shown, first, the vacuum pump 43 is turned on to achieve a negative pressure environment in the sealed chamber 42, and then 300 μL of nitrate nitrogen standard solution is introduced and reduced to nitrite nitrogen through the cadmium column and then injected into the sample mixing tank 28 through the test liquid injection tube 24 by the multi-position switching valve 23 using the pipeline 22. Then, the color developer is also injected into the sample mixing tank 28 through the color developer injection tube 25 by the multi-position switching valve 23 using the pipeline 22 to mix with the nitrite nitrogen. After a period of time until the color development is stable, the injection valve 20 is opened to inject the colored solution into the liquid core waveguide 1, and the bubbles in the liquid core waveguide 1 are eliminated by negative pressure. Then, the light emitting diode 31 is turned on in sequence by the controller, and the light generated is from the light emitting diode 31 to the photodetector 32, and then passes through the collimator 34 to enter the optical fiber 33, and then passes through the quartz light window 6 to enter the liquid core waveguide 1 and undergoes total internal reflection. The light signal is enhanced during the movement, and then is coupled to the photodetector 32 through the quartz light window 6, the optical fiber 33 and the collimator 34 in sequence, and converted into an electrical signal and transmitted to the processor. After calculation, the linearity of the standard curve and the actual nitrate content in the soil leaching solution are displayed on the terminal device respectively. Compared with the traditional 1cm optical path cuvette measurement, the sensitivity of this method has been improved, and the detection limit is as low as 20ppb, which is far lower than the average level of nitrate nitrogen in the farmland soil leaching solution, and the stability and repeatability are good. The results show that: during the entire measurement process, there is no phenomenon of light path blocking due to the presence of bubbles, and the detection system can effectively complete the determination of nitrate nitrogen in the farmland soil leaching solution.

[0038] Application Example 2:

[0039] Hexavalent chromium, as a toxic substance, has been listed in the national list of toxic and harmful water pollution. Long-term drinking of water containing hexavalent chromium will cause harm to the digestive system, affect normal physiological metabolism, and even cause damage to important organs such as the kidneys and liver, causing irreversible damage. Therefore, it is of great significance to determine hexavalent chromium in water for daily use.

[0040] For this purpose, refer to the national standard GB / T 5750.6-2023 "Standard Test Methods for Drinking Water Part 6: Metal and Metalloid Indexes" on the determination method of hexavalent chromium, prepare a hexavalent chromium solution of known concentration as the standard solution, and prepare the corresponding color developer. Figure 1 In the device shown, the vacuum pump 43 is first turned on to realize the negative pressure environment in the sealed chamber 42, and then 300 μL of hexavalent chromium standard solution and developer are respectively introduced into the sample mixing pool 28 through the test liquid injection tube 24 and the developer injection tube 25. After a period of time, the injection valve 20 is opened to inject the colored solution into the liquid core waveguide 1 after the color development is stable, and the bubbles in the liquid core waveguide 1 are eliminated by negative pressure. Then, the light emitting diodes 31 are turned on in sequence by the controller, and the generated light is from the light emitting diodes 31 to the photodetector 32, and then passes through the collimator 34 to enter the optical fiber 33, and then passes through the quartz light window 6 to enter the liquid core waveguide 1 and undergoes total internal reflection. The light signal is enhanced during the movement, and then is coupled to the photodetector 32 through the quartz light window 6, the optical fiber 33 and the collimator 34 in sequence, and converted into an electrical signal and transmitted to the processor. After calculation, the linearity of the standard curve and the nitrite content of the actual aqueous solution are respectively displayed on the terminal device. Compared with traditional colorimetric measurement, the sensitivity of this method has been improved, and the detection limit is as low as 8ppb, which meets the limit requirement of hexavalent chromium in drinking water quality (0.05mg / L) in GB 5749-2022 "Sanitary Standard for Drinking Water", and has good stability and repeatability. The results show that during the entire measurement process, there is no phenomenon of light path blocking due to the presence of bubbles, and the detection system can effectively complete the detection of hexavalent chromium in drinking water.

[0041] Of course, the present invention may have many other implementation modes. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A liquid core waveguide in-situ online multi-component high-sensitivity detection system, characterized in that: It comprises a liquid core waveguide (1) made of Teflon AF material, as well as a flow path structure, a detection structure and a degassing structure; The degassing structure comprises a degassing tube (41), the liquid core waveguide tube (1) passes through the degassing tube (41), and a sealed cavity (42) is formed between the liquid core waveguide tube (1), the sealed cavity is connected to a vacuum pump (43) through a pipeline, and three-way tubes (5) are provided at both ends of the liquid core waveguide tube (1), one end of the three-way tube (5) serves as a port for light to pass through and is sealed by a quartz light window (6), and the other end serves as a port for detection liquid to pass through; A light emitting diode (31) and a photodetector (32) are arranged at positions close to both ends of the liquid core waveguide (1), the three-way pipe (5) is located at one end of the quartz light window (6), and an optical fiber (33) is arranged through a flange (7) in a direction away from the liquid core waveguide (1), a collimator (34) is provided at the end of the optical fiber (33), and the quartz light window (6), the light emitting diode (31), the photodetector (32), the optical fiber (33), the collimator (34) and the liquid core waveguide (1) are all located on the same straight line to form the detection structure; One of the three-way pipes (5) is connected to a liquid discharge pipe (21) at a port for the detection liquid to pass through, and the other three-way pipe (5) is connected to a multi-position switching valve (23) at a port for the detection liquid to pass through a pipeline (22). The multi-position switching valve (23) is also respectively connected to a test liquid injection pipe (24) and a color developer injection pipe (25). The liquid discharge pipe (21) is provided with a liquid discharge valve (26) to form the flow path structure.

2. The liquid core waveguide in-situ online multi-component high-sensitivity detection system according to claim 1, characterized in that: The multi-position switching valve (23) is also connected to an air extraction pipe (27), and the air extraction pipe (27) is connected to an air extraction pump.

3. The liquid core waveguide in-situ online multi-component high-sensitivity detection system according to claim 2, characterized in that: The pipeline (22) is provided with a liquid injection valve (20), and a sample mixing pool (28) is also provided at a location between the multi-position switching valve (23) and the liquid injection valve (20).

4. The liquid core waveguide in-situ online multi-component high-sensitivity detection system according to any one of claims 2 to 3, characterized in that: The multi-position switching valve (23) is also connected to a gas-liquid injection pipe (29).

5. The liquid core waveguide in-situ online multi-component high-sensitivity detection system according to claim 4, characterized in that: The liquid discharge pipe (21) and the pipeline (22) are both made of polytetrafluoroethylene material.

6. The liquid core waveguide in-situ online multi-component high-sensitivity detection system according to claim 5, characterized in that: It also includes a controller for controlling the operating status of the multi-position switching valve (23), the drain valve (26), the light-emitting diode (31), the vacuum pump (43) and the air extraction pump, and a processor connected to the photoelectric detector (32). The controller and the processor are respectively connected to the terminal device through a wireless communication module, and the terminal device includes a computer, a mobile phone and a tablet.

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