A method and device for quantitative analysis of trace urea

Abstract

The present invention belongs to the technical field of water quality analysis, and specifically, is a method and device for quantitatively analyzing trace urea, wherein the method for quantitatively analyzing trace urea comprises the following steps: S1, influent water first passes through an injection pump P1 and a flow sensor F1; S2, after influent water enters a pretreatment unit, it enters an ultraviolet decomposer A and an organic adsorber B in sequence; S3, the pretreated influent water is pumped into a micro-injector C through a peristaltic pump W; S4, during injection, the sample solution is mixed with carrier water, and then enters a detection unit; S5, the carrier water enters the detection unit to analyze the urea concentration; according to the method and device for quantitative analysis of trace urea of ​​the present invention, the urea concentration of raw water or produced water prepared by ultrapure water in a semiconductor / liquid crystal panel factory can be accurately measured, and the method has the advantages of high accuracy, high precision and high degree of device integration.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality analysis, in particular to a method and a device for quantitatively analyzing trace urea. Background Art

[0002] Ultrapure water is an essential auxiliary material for the production of semiconductor / LCD panel products, and the water quality requirements are quite high. The raw water for the preparation of ultrapure water basically comes from municipal tap water. Municipal tap water is processed through a pretreatment system, a processing system, and a polishing system to obtain ultrapure water for the production of semiconductor / LCD panel products.

[0003] Sometimes, trace amounts of urea are mixed into municipal tap water, with a concentration of 50-200 ppb, which is only 10-40 ppb when converted into TOC. However, the ultrapure water preparation system has limited ability to remove urea, which eventually causes the TOC of the produced water to exceed the standard, affecting the production yield and causing huge economic losses to semiconductor / LCD panel factories. The existing ultrapure water system is designed with a urea removal unit at the raw water end, but the owner will reduce the actual operating time in order to reduce operating costs; the urea removal unit will be started again when the TOC of the produced water exceeds the standard, which will still bring certain economic losses. Even if a TOC meter is set at the raw water end, the addition of trace urea will not cause huge fluctuations in TOC; if there is online monitoring of trace urea and the urea removal unit is operated in time, economic losses can be avoided.

[0004] The existing literature on urea detection technology is as follows:

[0005] Patent document 1: 201711338043.0; Using the spectrophotometric measurement method, using the principle of the reaction of diacetyl monoxime and antipyrine reagent with urea, setting the sample cup, sampling multi-way valve, cleaning multi-way valve, first mechanical arm unit and second mechanical arm unit and other components to analyze the urea content in the water sample. However, this method uses large components, the degree of equipment integration is not high, the sampling is cumbersome, the detection cycle is as long as 52 minutes, the practicality is poor, and it does not meet the continuous detection requirements of the pure water system.

[0006] Patent document 2: 201810341217.7; Using a neutral red indicator, a sample to be tested, and a polyethylene glycol mixed solution as the inner aqueous phase, and a urease and dextran mixed solution as the outer aqueous phase, the urea content is analyzed by a microfluidic control device. The operating cost is low, and a single sample test only takes 10 to 20 seconds. However, this method still cannot be used for the detection of raw water for pure water preparation. This is because the enzyme effect of the enzymatic reaction is limited when the reactant concentration is low, and the actual use effect is not good.

[0007] Patent document 3: 201880021497.1; A method for quantifying urea in sample water by using a colorimetric assay of diacetyl monoxime, in particular, refrigerating the reagents used for the reaction. However, diacetyl monoxime does not only react with urea to produce color, but also reacts with its metabolite citrulline to produce color. This measurement method cannot exclude the influence of citrulline; and the detection principle of this method has limited accuracy, with a detection limit of 0.1ppm, and cannot detect lower trace amounts of urea. It is mostly used in places such as swimming pools and is not suitable for urea detection in raw water preparation from pure water.

[0008] It can be seen from the above content that the existing technology has the problems of limited detection principle accuracy, inability to measure trace urea, and low degree of automation and integration of equipment sampling; in view of the above problems, the present invention aims to provide a method and device for quantitative analysis of trace urea. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a method and device for quantitative analysis of trace urea, which utilizes flow injection analysis technology and advanced oxidation technology to quantitatively analyze the urea concentration of raw water or produced water. According to the purpose of the present invention, a method for quantitative analysis of trace urea is provided, and the method comprises the following steps:

[0010] The water in S1 first passes through the injection pump P1 and flow sensor F1;

[0011] After the S2 influent enters the pretreatment unit, it enters the UV decomposer A and the organic adsorber B in sequence;

[0012] S3 The pre-treated water is pumped into the micro-injector C through the peristaltic pump W;

[0013] During S4 injection, the sample solution will be mixed with the carrier water and then enter the detection unit;

[0014] S5 carries water into the detection unit to analyze the urea concentration.

[0015] Preferably, the main body of the ultraviolet decomposer A is an ultraviolet lamp tube with a quartz sleeve on the outside, using vacuum ultraviolet rays with a wavelength range of 100~200nm, and the main body of the organic adsorber B is an ion exchange resin, using a domestic high-quality brand of macroporous strong base resin and macroporous weak base resin, 1~2BV / h, and a ratio of 2:1~3:1.

[0016] Preferably, the microinjector C body is a six-way valve, which includes six ports and an annular pipeline, the six ports are numbered 1', 2', 3', 4', 5' and 6' respectively; the annular pipeline is connected to the two ports 2' and 5', and the liquid flow direction in the annular pipeline is 2'→5'.

[0017] Preferably, the carrier water is provided with a circulation unit, and the carrier water in the circulation pool G is pressurized by the injection pump P2 and enters the carrier water pipeline ③, passes through the flow sensor F2, the ion absorber D and the heating coil HC, enters the annular pipeline of the micro-injector C, and mixes with the sample solution. The carrier water passes through the 3'→2'→5'→4' ports in sequence.

[0018] Preferably, the detection unit is provided with conductivity cell C1 and conductivity cell C2, reagent injection device and mixing coil MC on the detection pipeline ④, and the urea concentration is obtained by measuring the conductivity difference before and after the advanced oxidation of the water carrier.

[0019] A device for quantitative analysis of trace urea, the device is a peristaltic pump W used in S3 in the above step; the peristaltic pump includes a motor, a shell, a pump head, a rotor, a roller and a pump tube; an anti-wear mechanism is arranged inside the peristaltic pump; the anti-wear mechanism includes a push plate, a connecting plate and a limit rod; the push plate is located between the pump tube and the pump head, the push plate is in an arc shape, the convex surface of the push plate is attached to the pump tube, the concave surface of the push plate is attached to the roller, the push plate is fixedly connected to the connecting plate on the surface opposite to the bottom of the shell, and the connecting plate passes through the gap between the pump tube and the inner bottom surface of the shell, a sliding hole is provided on the connecting plate, and the gap in the sliding hole matches the limit rod; the limit rod is located above the pump tube, and one end of the limit rod is fixedly connected to the inner bottom surface of the shell.

[0020] Preferably, a return spring is provided in the sliding hole; one end of the return spring is fixedly connected to the side wall of the sliding hole, and the other end of the return spring is fixedly connected to the limiting rod.

[0021] Preferably, a limiting plate is provided at the other end of the limiting rod; the limiting plates are two in number, and the limiting plates are symmetrically fixed to the other end of the limiting rod.

[0022] Preferably, a slide groove is respectively provided on both sides of the slide hole; and the end of the limit plate is slidably connected in the slide groove.

[0023] Preferably, the slide groove is in an arc shape, and the inner concave surfaces of the slide groove are designed to be relatively opposite.

[0024] The beneficial effects of the present invention are as follows:

[0025] According to the trace urea quantitative analysis method and device of the present invention, the urea concentration of raw water or produced water for preparing ultrapure water in semiconductor / liquid crystal panel factories can be accurately measured, and the method has the following advantages:

[0026] 1. High accuracy. The present invention adopts advanced oxidation technology. The generated hydroxyl radicals (·OH) can effectively react with trace urea. After testing, it can accurately measure 20~1000ppb trace urea.

[0027] Second, high precision. The present invention adopts flow injection analysis technology. The volume of the measured sample is constant, and the conditions such as residence time in the pipeline, reaction temperature and turbulence intensity are the same. The measurement results have good reproducibility and high precision.

[0028] 3. The device has a high degree of integration. The device highly integrates pretreatment unit, micro-injector, detection unit, water circulation unit, dual water inlet and outlet channels, injection pump, flow sensor, heating coil, mixing coil, ion absorber and other components, with a high degree of integration.

[0029] The peristaltic pump used has an anti-wear mechanism installed between the pump tube and the roller to prevent the roller from causing destructive wear to the pump tube, thereby extending the service life of the pump tube; the limit plate slides in the arc-shaped slide groove, so that the movement trajectory of the connecting plate is restricted, so that the effective action point of the push plate squeezing the pump tube is restricted, so that the amount of extrusion deformation of the pump tube each time remains the same, and thus the amount of liquid flowing out of the pump tube remains the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the loading gear of the trace urea analysis device of the present invention;

[0032] Figure 2 This is a schematic diagram of the sample feed block of the trace urea analysis device of the present invention;

[0033] Figure 3 The relationship diagram between raw water urea concentration and conductivity (C1, C2, C2-C1);

[0034] Figure 4 1 is a perspective view of a peristaltic pump W used in the present invention;

[0035] Figure 5 is a cross-sectional view of a peristaltic pump W used in the present invention;

[0036] Figure 6 yes Figure 5 A partial enlarged view of the middle A;

[0037] In the figure: motor 1, housing 2, pump head 11, rotor 12, roller 121, pump tube 21, anti-wear mechanism 3, push plate 31, connecting plate 32, sliding hole 321, return spring 322, sliding groove 323, limit rod 33, limit plate 331. DETAILED DESCRIPTION

[0038] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with the implementation methods.

[0039] like Figures 1 to 3 As shown,

[0040] A method for quantitatively analyzing trace urea, the method comprising the following steps:

[0041] The S1 inlet water first passes through the injection pump P1 and the flow sensor F1; the injection pump P1 pressurizes the inlet water to ensure that the inlet water can pass through the subsequent components smoothly; the flow sensor F1 detects the fluid flow and provides the fluid signal in the pipeline to facilitate maintenance and repair. The pressurized inlet water can enter the pretreatment unit through the pipeline ①, and the front end of the pipeline ① is equipped with a maintenance valve. When the device is overhauled, the maintenance valve is closed and the inlet water can directly enter the drainage pipeline ②;

[0042] After the S2 influent enters the pretreatment unit, it enters the UV decomposer A and the organic adsorber B in sequence;

[0043] S3 The pretreated influent water is pumped into the micro-injector C through a peristaltic pump W; a peristaltic pump is used here, and the influent water passes through the ultraviolet decomposer A and the organic adsorber B in sequence, and the water pressure is weakened. At this time, the water pressure is difficult to ensure that it passes smoothly through the micro-injector C in the later stage. For this reason, a peristaltic pump W is used for pressurization treatment. Compared with a syringe pump, a peristaltic pump has a simple structure, convenient maintenance, and low cost. The most consumable part is the pump tube, which is easy to wear and break. However, in the present invention, the peristaltic pump is improved, and the service life of the peristaltic pump is extended by an anti-wear mechanism;

[0044] During S4 injection, the sample solution will be mixed with the carrier water and then enter the detection unit;

[0045] S5 carries water into the detection unit to analyze the urea concentration.

[0046] The main body of the ultraviolet decomposer A is an ultraviolet lamp tube with a quartz sleeve on the outside, which uses vacuum ultraviolet rays with a wavelength range of 100-200nm, more specifically 180-190nm, preferably 185nm. The 185nm ultraviolet germicidal lamp can convert oxygen in the air into ozone. Ozone has a strong oxidizing effect and can effectively kill bacteria and eliminate the influence of other organisms on the experiment; the main body of the organic adsorber B is an ion exchange resin, which uses a domestic high-quality brand of macroporous strong base resin and macroporous weak base resin, 1-2BV / h, and a ratio of 2:1-3:1; the ultraviolet decomposer A can remove large molecular organic matter in the influent water, but cannot remove small molecular organic matter urea; the organic adsorber B can effectively adsorb large molecular organic matter, but cannot adsorb small molecular organic matter urea; in order to improve the detection accuracy of the instrument, the influent requires TOC<2ppm to ensure that the pretreatment unit can effectively eliminate the influence of large molecular organic matter.

[0047] The micro-injector C is a six-way valve, which includes six ports and a ring pipeline. The six ports are numbered 1', 2', 3', 4', 5' and 6' respectively; the ring pipeline is connected to the two ports 2' and 5', and the liquid flow direction in the ring pipeline is 2'→5'.

[0048] The carrier water is provided with a circulation unit. The carrier water in the circulation pool G is pressurized by the injection pump P2 and enters the carrier water pipeline ③. After passing through the flow sensor F2, the ion absorber D and the heating coil HC, it enters the annular pipeline of the micro-injector C and mixes with the sample solution. The carrier water passes through the 3'→2'→5'→4' ports in sequence; the ion absorber D is mainly an ion exchange resin, which adopts a domestic high-quality brand of gel-type strong acid resin and gel-type strong base resin, 40~60BV / h, and the ratio is 3:1; experiments have found that the advanced oxidation technology of urea has certain requirements for temperature, and setting a suitable temperature can improve the detection accuracy of urea; the carrier water flow is constant, the volume of the sample solution in the annular pipeline is constant, and after calculation, a heating coil HC with a certain power is selected to keep the carrier water at a suitable temperature, and the temperature is selected to be 20~30℃, preferably 23~25℃.

[0049] The detection unit is provided with conductivity cell C1 and conductivity cell C2 as well as reagent injection device and mixing coil MC on detection pipeline ④, and the urea concentration is obtained by measuring the conductivity difference before and after the advanced oxidation of carrier water; after the carrier water is mixed with a certain volume of reagents E and F in reagent pipelines ⑤ and ⑥, it passes through conductivity cell C1, passes through mixing coil MC to promote the reaction, and finally enters circulation pool G through drainage pipeline ⑦ through conductivity cell C2 and flow sensor F5; reagents E and F respectively have injection pumps P3, P4 and flow sensors F3, F4 to control the reagent volume and transmit fluid signals, and the signal of flow sensor F5 is used as the basis for maintenance and inspection of the detection unit. Reagent E is an alkaline reagent, which can be a sodium hydroxide or potassium hydroxide solution, with a concentration of 0.5-2%, preferably 1%; Reagent F is an oxidant combination, which is a mixed solution of hypochlorite and bromide salt, preferably sodium salt, with a hypochlorite concentration of 7-10mM, a bromide concentration of 10-15mM, and a molar ratio of hypochlorite to bromide salt of 0.6-0.7; The volume and concentration of each solution are constant, and a working curve of the standard solution is drawn according to the comparison method, and the urea concentration in the sample solution is analyzed thereby.

[0050] Example 1: The preliminary advanced oxidation method experiment is as follows: 2000 mL of ultrapure water (TOC <1ppb) was taken from a pure water station in a semiconductor factory for experiment. At 23°C, the dosage of NaClO and NaBr was adjusted, and the pH value of the process was reasonably adjusted. Among them, the best advanced oxidation effect was as follows: 200 ppb urea solution was prepared, the water bath was heated to control 23°C, 10 ppm NaClO solution and 22 ppm NaBr solution were added, the pH was adjusted to 8.5~9.0, and after 30 minutes, the urea concentration of the solution was found to be 40 ppb.

[0051] Under the above experimental conditions, the temperature was changed to conduct experiments and Table 1 was obtained. It was found that the temperature had a greater impact on the reaction.

[0052] Serial number Temperature / ℃ Outlet urea concentration / ppb 1 15 132 2 18 99 3 20 67 4 23 40 5 25 42 6 27 40 7 30 38

[0053] Table 1

[0054] Example 2: The present invention is formed by Example 1. According to the method described in the present invention, the corresponding device is assembled: 20 ppb, 50 ppb, 100 ppb, 250 ppb, 500 ppb, 750 ppb, and 1000 ppb urea standard solutions are respectively supplied to the water inlet, and then the urea concentration of the standard solution is continuously monitored. The number of measurements for each standard solution is 10 times, and the results are averaged. The measurement time of a single data is 2 min (the micro-injector is shifted once every 1 min), and the relationship diagram between the raw water urea concentration and the conductivity (C1, C2, C2-C1) is measured ( Figure 3 );exist Figure 3 In the example, the injection pump P1 has a flow rate of 5 mL / min; the UV decomposer A uses a UV lamp with a wavelength of 185 nm and a power of 4W; the organic adsorber B is filled with 30 mL of resin, 1 BV / h, and the ratio of macroporous strong base resin to macroporous weak base resin is 3:1; the volume of the sample loop of the microinjector C is 500 µL; the injection pump P2 has a flow rate of 10 mL / min; the ion absorber D is filled with 150 mL of resin, 40 BV / h, and the ratio of gel-type strong base resin to gel-type strong acid resin is 3:1; the heating coil HC has a resistance of 10 Ω and a carrier water temperature of 23 °C; the reagent E is a 1% sodium hydroxide solution, and the injection pump P3 has a flow rate of 50 µL / min; the reagent F is a mixed solution of sodium hypochlorite and sodium bromide, with a sodium hypochlorite concentration of 9 mM, a sodium bromide concentration of 14 mM, a sodium hypochlorite and sodium bromide molar ratio of 0.6, and the injection pump P4 has a flow rate of 0.5 mL / min.

[0055] like Figure 4-Figure 6 As shown,

[0056] A device for quantitatively analyzing trace urea, the device is a peristaltic pump W used in S3; the peristaltic pump W comprises a motor 1, a housing 2, a pump head 11, a rotor 12, a roller 121 and a pump tube 21; an anti-wear mechanism 3 is provided inside the peristaltic pump W; the anti-wear mechanism 3 comprises a push plate 31, a connecting plate 32 and a limit rod 33; the push plate 31 is located between the pump tube 21 and the pump head 11, the push plate 31 is in an arc shape, the convex surface of the push plate 31 is attached to the pump tube 21, and the push plate 31 is in an arc shape. The concave surface of the plate 31 is attached to the roller 121, and the push plate 31 is fixedly connected to the connecting plate 32 on the surface opposite to the bottom of the shell 2, and the connecting plate 32 passes through the gap between the pump tube 21 and the inner bottom surface of the shell 2. A sliding hole 321 is provided on the connecting plate 32, and the clearance in the sliding hole 321 fits the limiting rod 33; the limiting rod 33 is located above the pump tube 21, and one end of the limiting rod 33 is fixedly connected to the inner bottom surface of the shell 2; when the peristaltic pump W is working, the roller 121 rotates around the center position of the rotor 12, The roller 121 squeezes the pump tube 21 to generate a friction block, pushing the liquid in the pump tube 21 out of the pump tube 21. At the same time, rolling friction occurs between the roller 121 and the pump tube 21. The surface of the roller 121 rubs the pump tube 21. After the pump tube 21 runs for a long time, the wall of the pump tube 21 gradually wears and becomes thinner. In severe cases, the pump tube 21 wears and breaks, and the liquid leaks, making the peristaltic pump W unusable. For this reason, an anti-friction mechanism 3 is arranged between the pump tube 21 and the roller 121 to prevent the roller 121 from damaging the pump tube. 21 produces destructive wear; when the roller 121 rotates around the center of the rotor 12, the roller 121 squeezes the push plate 31, the push plate 31 squeezes the pump tube 21, and then the liquid in the pump tube 21 is squeezed out, and at the same time, the push plate 31 pushes the connection, and the through hole of the connecting plate 32 is restricted by the limit rod 33, and the connecting plate 32 moves upward. When the roller 121 does not squeeze the push plate 31, the push plate 31 is pushed back to the initial position by the elasticity of the pump tube 21, so that the pump tube 21 is pumped into new liquid again.

[0057] As an embodiment of the present invention, a return spring 322 is provided in the slide hole 321; one end of the return spring 322 is fixedly connected to the side wall of the slide hole 321, and the other end of the return spring 322 is fixedly connected to the limit rod 33; when the connecting plate 32 moves, the connecting plate 32 squeezes the return spring 322, and at the same time the return spring 322 pulls the limit rod 33 and pulls the push plate 31 downward, at this time the push plate 31 moves downward, and at the same time the roller 121 is able to effectively squeeze the push plate 31 again, the push plate 31 squeezes the pump tube 21, and the squeezed recessed part of the pump tube 21 no longer squeezes the push plate 31 and then returns to the initial state, so that the pump tube 21 is promptly restored to the liquid suction state, so that the pump tube 21 can effectively suck in liquid.

[0058] As an embodiment of the present invention, a limiting plate 331 is provided at the other end of the limiting rod 33; there are two limiting plates 331, which are symmetrically fixed to the other end of the limiting rod 33; the connecting plate 32 is moved to the inner bottom surface of the shell 2 through the limiting plate 331 to prevent the end of the connecting plate 32 from warping, making it difficult for the push plate 31 to effectively squeeze the pump tube 21.

[0059] The two sides of the sliding hole 321 each define a sliding groove 323 ; the end of the limiting plate 331 is slidably connected in the sliding groove 323 .

[0060] As an embodiment of the present invention, the slide groove 323 is arc-shaped, and the inner concave surfaces of the slide groove 323 are relatively designed; the limiting plate 331 slides in the arc-shaped slide groove 323, so that the moving trajectory of the connecting plate 32 is restricted, so that the effective action point of the push plate 31 squeezing the pump tube 21 is restricted, so that the amount of extrusion deformation of the pump tube 21 remains the same each time, and thus the amount of liquid flowing out of the pump tube 21 remains the same.

[0061] Working principle: When the roller 121 rotates around the center of the rotor 12, the roller 121 squeezes the push plate 31, the push plate 31 squeezes the pump tube 21, and then the liquid in the pump tube 21 is squeezed out, and at the same time the push plate 31 pushes the connection, and the through hole of the connecting plate 32 is restricted by the limit rod 33, and the connecting plate 32 moves upward. When the roller 121 does not squeeze the push plate 31, the push plate 31 is pushed back to the initial position by the elasticity of the pump tube 21, so that the pump tube 21 draws new liquid again; by arranging the anti-wear mechanism 3 between the pump tube 21 and the roller 121, the roller 121 is prevented from causing destructive wear to the pump tube 21, thereby extending the service life of the pump tube 21; and when the connecting plate 32 moves, the connecting plate 32 squeezes the reset spring 322, and at the same time, the return spring 322 pulls the limit rod 33 and pulls the push plate 31 downward. At this time, the push plate 31 moves downward, and the roller 121 is able to effectively squeeze the push plate 31 again. The push plate 31 squeezes the pump tube 21 and the squeezed recessed part of the pump tube 21 no longer squeezes the push plate 31 and then returns to its initial state, so that the pump tube 21 is restored to the liquid suction state in time, so that the pump tube 21 can effectively suck the liquid; at the same time, the limit plate 331 slides in the arc-shaped slide groove 323, so that the moving trajectory of the connecting plate 32 is restricted, so that the effective action point of the push plate 31 squeezing the pump tube 21 is restricted, so that the amount of deformation of the pump tube 21 each time is kept the same, so that the amount of liquid flowing out of the pump tube 21 remains the same.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for quantitative analysis of trace urea, characterized in that: The method comprises the following steps: The water in S1 first passes through the injection pump P1 and flow sensor F1; After the S2 influent enters the pretreatment unit, it enters the UV decomposer A and the organic adsorber B in sequence; S3 The pre-treated water is pumped into the micro-injector C through the peristaltic pump W; During S4 injection, the sample solution will be mixed with the carrier water and then enter the detection unit; S5 carries water into the detection unit to analyze the urea concentration; The micro-injector C is a six-way valve, which includes six ports and an annular pipeline. The six ports are numbered 1', 2', 3', 4', 5' and 6' respectively; the annular pipeline is connected to the two ports 2' and 5', and the liquid flow direction in the annular pipeline is 2'→5'; The carrier water is provided with a circulation unit. The carrier water in the circulation pool G is pressurized by the injection pump P2 and enters the carrier water pipeline ③. After passing through the flow sensor F2, the ion absorber D and the heating coil HC, it enters the annular pipeline of the micro-injector C and mixes with the sample solution. The carrier water passes through the 3'→2'→5'→4' ports in sequence. The detection unit is provided with conductivity cell C1 and conductivity cell C2, reagent injection device and mixing coil MC on the detection pipeline ④, and the urea concentration is obtained by measuring the conductivity difference before and after the advanced oxidation of the water carrier.

2. A method for quantitative analysis of trace urea according to claim 1, characterized in that: The main body of the ultraviolet decomposer A is an ultraviolet lamp tube with a quartz sleeve on the outside, using vacuum ultraviolet light with a wavelength range of 100-200nm, and the main body of the organic adsorber B is an ion exchange resin.

3. A device for quantitative analysis of trace urea, based on the method for quantitative analysis of trace urea described in claim 1, characterized in that: The peristaltic pump W used in step S3 includes a motor, a shell, a pump head, a rotor, a roller and a pump tube; an anti-wear mechanism is provided in the peristaltic pump; the anti-wear mechanism includes a push plate, a connecting plate and a limit rod; the push plate is located between the pump tube and the pump head, the push plate is in an arc shape, the convex surface of the push plate is attached to the pump tube, the concave surface of the push plate is attached to the roller, the connecting plate is fixedly connected to the surface of the push plate opposite to the bottom of the shell, and the connecting plate passes through the gap between the pump tube and the inner bottom surface of the shell, a sliding hole is provided on the connecting plate, and the gap in the sliding hole matches the limit rod; the limit rod is located above the pump tube, and one end of the limit rod is fixedly connected to the inner bottom surface of the shell.

4. A device for quantitative analysis of trace urea according to claim 3, characterized in that: A return spring is arranged in the sliding hole; one end of the return spring is fixedly connected to the side wall of the sliding hole, and the other end of the return spring is fixedly connected to the limiting rod.

5. A device for quantitative analysis of trace urea according to claim 3, characterized in that: The other end of the limit rod is provided with a limit plate; the number of the limit plates is two, and the limit plates are symmetrically fixed to the other end of the limit rod.

6. A device for quantitative analysis of trace urea according to claim 5, characterized in that: A sliding groove is respectively provided on both sides of the sliding hole; and the end of the limiting plate is slidably connected in the sliding groove.

7. A device for quantitative analysis of trace urea according to claim 6, characterized in that: The slide groove is in an arc shape, and the inner concave surfaces of the slide groove are designed to be opposite to each other.

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