Rapid detection method for ammonia nitrogen in environmental water body

Abstract

The invention discloses a method for rapidly detecting ammonia nitrogen in environmental water, which comprises the following steps: fixing alanine dehydrogenase (AlaDH) on the surface of core-shell Fe3O4 (at) Au nanoparticles to construct a biosensing membrane, and combining with an ammonium ion sensitive membrane consisting of polyvinyl chloride (PVC), sodium tetraphenylborate (NaTFPB), 2-nitrophenyl octyl ether (NPOE) and nonactin according to the mass ratio of 65.6: 0.6: 131.8: 2 to form an all-solid-state electrode. The detection lower limit reaches 0.05 mg / L, the linear range is 10 <-1 >-10 <-8 > M, the response time is only 100 seconds, the NH4 < + > selectivity coefficient (K < + > / NH4 < + >) is 0.01, and the anti-interference rate is lt; the signal attenuation rate is 1t after continuous use for 30 days; 5%. A potential-concentration logarithmic model is established through an open circuit potentiometry, and the ammonia nitrogen concentration in an environmental water body can be rapidly measured. The method is suitable for online monitoring of water bodies such as lakes, rivers and industrial wastewater, and an efficient and reliable technical means is provided for ammonia nitrogen pollution prevention and control.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental detection, and particularly relates to a rapid detection method for ammonia nitrogen in environmental water bodies. Background Art

[0002] Ammonia nitrogen (NH4 + -N) mainly exists in two forms: non-ionic ammonia (or free ammonia, NH3) and ionic ammonia (or ammonium ion, NH4 + ). In the environmental water body system, the form of ammonium / ammonia depends on the pH. When the pH value is higher than 9.75, it mainly exists in the form of non-ionic ammonia. The pH value of most environmental water bodies is lower than 8.75, and ammonium is the main form, with much less ammonia present. As a common indicator for judging the pollution situation of environmental water bodies, it is crucial to obtain ammonia nitrogen data in real time and accurately.

[0003] Ammonia nitrogen (NH4 + / NH3) is an important indicator for evaluating the degree of water body pollution. Its excessive discharge can lead to water eutrophication, depletion of dissolved oxygen, and pose a serious threat to aquatic organisms and human health. Currently, ammonia nitrogen detection methods mainly include spectrophotometry, ion chromatography, and traditional ion-selective electrode methods. However, these methods have the following problems:

[0004] (1) Spectrophotometry: It requires complex pretreatment (such as water sample distillation, color reaction), is time-consuming, and is easily interfered by turbidity and organic matter.

[0005] (2) Traditional ion-selective electrode: The sensitive membrane is prone to aging, has poor stability (signal attenuation > 10% / month), and insufficient anti-interference ability (K + NH4 + > 0.1).

[0006] (3) Unable to perform on-line monitoring: Existing technologies rely on laboratory equipment and it is difficult to achieve on-site real-time detection.

[0007] In view of the above problems, the present invention has developed an all-solid-state ammonium ion-selective electrode by the magnetic fixation and catalytic synergy of core-shell Fe3O4@Au nanoparticles, combined with optimizing the sensitive membrane formulation, significantly improving the detection sensitivity, anti-interference ability, and stability. Summary of the Invention

[0008] In order to overcome the problems in the background art, the present invention provides a rapid detection method for ammonia nitrogen in environmental water bodies.

[0009] To achieve the above object, the present invention is realized by the following technical solutions:

[0010] A rapid detection method for ammonia nitrogen in environmental water bodies, comprising the following steps:

[0011] (1) Prepare core-shell Fe3O4@Au nanoparticles, where the size of the Fe3O4 core is 50 - 100 nm and the thickness of the Au shell is 5 - 10 nm;

[0012] (2) Immobilize alanine dehydrogenase (AlaDH) on the surface of the core-shell Fe3O4@Au nanoparticles to form an enzyme-based biosensing membrane;

[0013] (3) Mix polyvinyl chloride (PVC), sodium tetraphenylborate (NaTFPB), 2-nitrophenyl octyl ether (NPOE), and nonactin in a mass ratio of 65.6:0.6:131.8:2, and dissolve them in tetrahydrofuran (THF) to prepare an ammonium ion-sensitive membrane solution;

[0014] (4) Coat the sensitive membrane solution on the surface of a glassy carbon electrode (GCE) modified with Fe3O4@Au / AlaDH, and dry it to form an all-solid-state ammonium ion-selective electrode;

[0015] (5) Immerse the electrode in the water sample to be measured, measure the potential response by the open-circuit potential method, and calculate the ammonia nitrogen concentration by combining with the standard curve.

[0016] As a preferred technical solution of the present invention, the immobilization method of the alanine dehydrogenase in step (2) is: incubate the Fe3O4@Au nanoparticles with the AlaDH solution at 4 °C for 12 hours, and obtain an enzyme-nanoparticle complex after magnetic separation.

[0017] As a preferred technical solution of the present invention, the immobilization method of the alanine dehydrogenase in step (2) is: incubate the Fe3O4@Au nanoparticles with the AlaDH solution at 4 °C for 12 hours, and obtain an enzyme-nanoparticle complex after magnetic separation.

[0018] As a preferred technical solution of the present invention, the preparation method of the core-shell Fe3O4@Au nanoparticles in step (1) includes:

[0019] (a) Prepare Fe3O4 nanoparticles by the co-precipitation method and carry out amino modification;

[0020] (b) Mix the amino-functionalized Fe3O4 nanoparticles with the nanoparticle solution, stir and react for 8 hours to form a core-shell structure.

[0021] As a preferred technical solution of the present invention, the detection linear range of the ammonium ion-sensitive membrane is 10 -1 ~10 -8 M, the detection limit is 0.05 mg / L, and the response time is 100 seconds.

[0022] As a preferred technical solution of the present invention, the method for establishing the standard curve in step (5) is as follows:

[0023] (a) Prepare NH4Cl standard solutions with different concentrations in the range of 10 -1 ~10 -8 M, and adjust the pH of the solution with phosphate buffer solution (PBS) with pH = 7.4;

[0024] (b) Use the all-solid-state ammonium ion selective electrode to measure the open-circuit potential of each concentration solution and record the stable potential value;

[0025] (c) With the logarithm of ammonia nitrogen concentration as the abscissa and the potential response value as the ordinate, fit a linear relationship model.

[0026] As a preferred technical solution of the present invention, the signal attenuation rate of the all-solid-state ammonium ion selective electrode is less than 5% after continuous use for 30 days, and the repeatability error ≤ 3%.

[0027] As a preferred technical solution of the present invention, the reference electrode used in the detection method is an Ag / AgCl electrode, which is isolated from the solution to be measured through a salt bridge, and the salt bridge solution is saturated KCl solution.

[0028] As a preferred technical solution of the present invention, the combination of the enzyme-based biosensing membrane and the ammonium ion sensitive membrane makes the selectivity coefficient (K + / NH4 + / NH4 + ) of the electrode 0.01, and the interference rate is less than 5%.

[0029] As a preferred technical solution of the present invention, it includes:

[0030] (a) Glassy carbon electrode (GCE) substrate;

[0031] (b) Fe3O4@Au / AlaDH modification layer;

[0032] (c) Ammonium ion sensitive membrane composed of PVC, NaTFPB, NPOE and Nonactin.

[0033] As a preferred technical solution of the present invention, the thickness of the sensitive membrane is a thin film formed after drying 6 μL of the membrane solution is coated.

[0034] Advantages of the present invention:

[0035] (1) High sensitivity: The detection limit reaches 0.05 mg / L, which is suitable for low-concentration ammonia nitrogen water samples (such as drinking water sources).

[0036] (2) Wide linear range: covering 10 -1 ~10 -8M can detect water bodies with different pollution levels (such as industrial wastewater, rivers).

[0037] (3) Strong anti-interference ability: The selectivity coefficient (K + of nonactin in the sensitive membrane for NH4 + / NH4 + is 0.01), the interference rate < 5%, and it can effectively shield the interference of Na + , K + , Ca 2+ and other ions.

[0038] (4) Long-term stability: The signal attenuation of the all-solid-state electrode is < 5% after continuous use for 30 days, and the repeatability error ≤ 3%.

[0039] (5) Fast response: The detection is completed within 100 seconds, supporting on-site real-time monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for describing the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 is the flow chart of the present invention;

[0042] Figure 2 is the structural diagram of the all-solid-state ammonium ion selective electrode of the present invention;

[0043] Figure 3 is the conduction principle diagram of the solid contact layer of the present invention;

[0044] Figure 4 is the reaction principle diagram for detecting NH4 + of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] Embodiment 1

[0047] In this embodiment, refer to Figures 1 to 4As shown in the figure, the present invention needs to establish a relationship model to be applied to the detection of actual water areas. The specific steps are as follows:

[0048] 1. Prepare a test solution with a standard concentration using a standard ammonia nitrogen solution;

[0049] 2. Immerse the ammonium ion-selective nanobiosensor into the test solution and connect it to the working electrode interface of the electrochemical workstation, with the Ag / AgCl electrode as the reference electrode;

[0050] 3. Run the electrochemical workstation, set it to the open circuit potential method, and record the electrode potential for 100 s;

[0051] 4. Establish a relationship model between the potential response of the standard ammonia nitrogen water sample and the ammonia nitrogen concentration, and use it to predict the ammonia nitrogen concentration in the actual environmental water sample;

[0052] 5. Evaluate and optimize the performance of the ammonium ion-selective nanobiosensor according to the experimental results.

[0053] The specific design is as follows:

[0054] First, prepare a gold nanoparticle solution. Take 100 mL of ultrapure water, add 0.25 mL of a 0.1 mol / L chloroauric acid solution, and heat it to boiling under a magnetic stirrer; then quickly inject 1.5 mL of a 2% trisodium citrate solution, and reflux it for about 30 min under a reflux device until the solution turns wine red; stop heating and keep stirring, and gradually cool it to room temperature to obtain gold nanoparticles (AuNPs) with a size of about 18 nm. Finally, store it in the refrigerator for later use, and the storage temperature is 4 °C.

[0055] Secondly, take 2 g of Fe3O4 nanoparticles and ultrasonically disperse them in 50 mL of an aqueous solution containing 20% ethanol. Dropwise add 1 mL of 3-aminopropyltriethoxysilane (APTES), and stir it at room temperature for 12 h. After the reaction, it can be seen that the suspension with fine particles is light brown, and the obtained product is the amino-functionalized Fe3O4 nanoparticles. Wash the obtained product 3 times with a 0.1 mol / L HAc-ethanol solution by magnetic separation, and dry it for later use. Take 2 g of the above amino-functionalized Fe3O4 nanoparticles in a beaker, continuously stir them in a magnetic stirrer at 150 r / min at room temperature, and quickly add 20 mL of the prepared gold nanoparticle solution. The mixed solution gradually fades from brown, and after low-speed stirring for 8 h, Fe3O4@Au magnetic microparticles are obtained.

[0056] Then, 0.01 ml of alanine dehydrogenase (AlaDH) solution (4.28 U cm -3 ) in PBS is mixed with 0.1 ml of Fe3O4@Au nanoparticle suspension (0.015 mg cm -3)Mix for 30 min with a vortex mixer in a vial (1.5 cm3 microcentrifuge tube), then place the mixture in a refrigerator at 4 °C for 12 hours to immobilize AlaDH on Fe3O4@Au nanoparticles.

[0057] Next, modify the ammonium ion-sensitive membrane, which mainly consists of four parts: matrix material, ion exchanger, plasticizer, and ionophore. Since polyvinyl chloride (PVC) has good plasticity and processability, it can be made into films of different shapes and sizes. At the same time, it has high resistivity and dielectric constant, which can improve ion selectivity and effectively inhibit the interference of impurities. Therefore, polyvinyl chloride is selected as the matrix material. Sodium borate can accelerate the exchange of the sensitive membrane with ammonium ions in the solution and has good spatial shielding ability for the counterions of the ions to be measured, so it is often used as a cation additive. 2-Nitrophenyl octyl ether (NPOE) is one of the commonly used plasticizers in making ion-sensitive membranes. NPOE can form a mixture with the PVC matrix material, improve the plasticity and softness of the membrane within a certain temperature range, facilitate the processing and shaping of the membrane, and effectively inhibit the interference of impurity ions in the ion-sensitive membrane, improving signal stability and reliability. Therefore, NPOE is selected as the plasticizer. Nonactin has high selectivity for ammonium ions in the presence of various cations. It can form a complex with ammonium ions, and its coordination in the ion-sensitive membrane is relatively stable, which can improve the service life of the ion-sensitive membrane. Therefore, nonactin is selected as the ionophore. Take 65.6 mg of PVC, 0.6 mg of NaTFPB, 131.8 mg of NPOE, and 2 mg of nonactin and dissolve them in 1.0 ml of THF. Since the solubility of PVC is poor, the mixed solution is magnetically stirred for 30 min to prepare a polymer-sensitive membrane solution. Use a pipette to aspirate 6 μL of the membrane solution and drop it onto the Fe3O4@Au / AlaDH / GCE electrode, and then place it in an oven to dry to obtain an all-solid-state ammonium ion-selective electrode (Fe3O4@Au / AlaDH / GCE-ISE).

[0058] To determine the detection range of the prepared Fe3O4@Au / AlaDH / GCE-ISE, use this electrode to detect the potential in NH4Cl solutions with concentrations of 10 -1 M, 10 -2 M, 10 -3 M, 10 -4 M, 10 -5 M, 10 -6 M, 10 -7 M, 10 -8 M. Since NH4 +The concentration is easily affected by pH, so the solutions here are all prepared with PBS solution at pH = 7.4. Under the two-electrode system of the electrochemical workstation, the Ag / AgCl electrode is used as the reference electrode, and the Fe3O4@Au / AlaDH / GCE-ISE is used as the working electrode. The potential is detected for 100 s in each concentration solution. Since NH4 + will interfere with the Ag / AgCl reference electrode, thus affecting the accuracy and stability of the measurement. Therefore, a salt bridge protection is required, and the salt bridge solution is saturated KCl solution.

[0059] The response range of the electrode can be described by the concentration linear range. The concentration linear range refers to the range in which the electrical signal output by the ammonium ion selective electrode is linearly related to the ammonium ion concentration. By fitting the electrical signal output value with the corresponding ammonium ion concentration, the response equation of the electrode can be obtained, and the concentration linear range can be calculated by the slope of the response equation.

[0060] Example 2

[0061] This example mainly conducts a rapid detection of ammonia nitrogen in the environmental water body of a certain aquaculture factory in Dali.

[0062] 1. Implementation background

[0063] As the leading development of the local key aquaculture industry, the water quality safety of a certain aquaculture factory in Dali is of crucial importance. The ammonia nitrogen content, as a common indicator for judging water environmental pollution, has important guiding and prompting effects on fishery aquaculture. Therefore, it is very important to accurately obtain ammonia nitrogen data. It is necessary to regularly monitor the ammonia nitrogen concentration to evaluate the water quality safety. Traditional methods (such as Nessler reagent method) have problems such as cumbersome operation, high toxicity of reagents, and poor anti-interference ability. This example is based on the detection method proposed in the present invention and combines the actual water quality characteristics of a certain aquaculture factory (pH 6.8 - 7.5, common interfering ions are K + , Ca 2+ , Na + ) to optimize and verify the detection performance of the all-solid-state ammonium ion selective electrode.

[0064] 2. Experimental materials and equipment

[0065] Reagents: FeCl3·6H2O, FeCl2·4H2O, HAuCl4, alanine dehydrogenase (AlaDH, activity ≥ 200 U / mg), PVC, NaTFPB, NPOE, Nonactin, NH4Cl (analytical pure).

[0066] Instruments: magnetic stirrer, ultraviolet-visible spectrophotometer (to verify enzyme activity), electrochemical workstation (CHI660E), scanning electron microscope (SEM, to characterize nanoparticles).

[0067] Water sample: Surface water sample from a certain aquaculture farm in Dali (stored at 4°C after collection and detected within 24 hours).

[0068] 3. Experimental procedures and data

[0069] 3.1 Preparation of core-shell Fe3O4@Au nanoparticles

[0070] Steps:

[0071] Preparation of Fe3O4 nanoparticles by co-precipitation method: Dissolve Fe 3+ and Fe 2+ (molar ratio 2:1) in deoxygenated water, add ammonia water to adjust the pH to 10, react at 80°C for 1 hour, and perform amination modification after magnetic separation.

[0072] Construction of core-shell structure: Mix aminated Fe3O4 (particle size 80±10 nm, verified by SEM) with 0.1 mM HAuCl4 solution, stir for 8 hours, and the Au shell thickness is 8±2 nm (verified by TEM).

[0073] Optimization: By adjusting the concentration of HAuCl4 (0.05 - 0.2 mM), a uniform core-shell structure is obtained, and the CV value of the particle size distribution is <8%.

[0074] 3.2 Construction of enzyme-based biosensing membrane

[0075] Steps: Incubate Fe3O4@Au nanoparticles with AlaDH solution (1 mg / mL, pH 7.0 PBS) at 4°C for 12 hours. After magnetic separation, the enzyme loading is 0.15 μg / mg (determined by BCA method).

[0076] Data: The retention rate of immobilized enzyme activity is ≥90% (based on the activity of free enzyme, and the generation rate of NADH is determined by ultraviolet method).

[0077] 3.3 Preparation of ammonium ion-sensitive membrane

[0078] Formulation: PVC (65.6%), NaTFPB (0.6%), NPOE (131.8%), Nonactin (2%). After dissolving in THF, it is coated on the surface of Fe3O4@Au / AlaDH modified GCE, and the membrane thickness is about 5 μm after drying (SEM cross-section analysis).

[0079] Performance:

[0080] Detection linear range: 10 -1 ~10 -8 M (R 2 = 0.998), detection limit 0.03 mg / L (signal-to-noise ratio S / N = 3).

[0081] Response time: 80±10 s (10-4 MNH4 + (95% of the steady-state potential in the solution).

[0082] 3.4 Construction and Stability Test of All-Solid-State Electrodes

[0083] Electrode structure: GCE substrate → Fe3O4@Au / AlaDH modified layer → ammonium ion-sensitive membrane → Ag / AgCl reference electrode (salt bridge is saturated KCl).

[0084] Stability: After continuous use for 30 days, the signal attenuation rate is 2.8% (10 -4 M NH4 + solution), and the repeatability error is 2.1% (n = 5).

[0085] 4. Detection and Comparison of Actual Water Samples

[0086] 4.1 Establishment of Standard Curve

[0087] Prepare NH4Cl standard solution (10 -1 / ~10 -8 M, pH 7.4 PBS), measure the open-circuit potential (E / mV), and fit the equation: E = 58.2×log[NH4 + +120.3 (R 2 = 0.997).

[0088] 4.2 Detection of Water Samples from a Certain Aquaculture Farm

[0089] Pretreatment: The water sample is filtered through a 0.45μm filter membrane and the pH is adjusted to 7.4.

[0090] Result: The measured ammonia nitrogen concentration is 0.12 mg / L (this method) vs. 0.11 mg / L (ion chromatography method), and the relative deviation ≤ 5%.

[0091] 4.3 Anti-interference Test

[0092] Simulated water sample: Add 1 mM K + , Ca 2+ , Na + , and the ammonia nitrogen concentration is 0.1 mg / L.

[0093] Selectivity coefficient: K + / NH4 + = 0.008, and the interference rate < 3% (potential change < 2 mV).

[0094] 5. Comparison with Traditional Methods

[0095]

[0096] 6. Conclusion

[0097] This embodiment verifies the high efficiency of the detection method proposed by the present invention in the water samples of a certain aquaculture factory in Dali. It has the advantages of rapidity, high sensitivity, strong anti-interference, etc., and is suitable for on-site monitoring of environmental water bodies. The optimized Fe3O4@Au nanoparticle and sensitive film formulations further improve the detection performance, providing reliable technical support for water quality safety management.

[0098] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A rapid detection method for ammonia nitrogen in environmental water bodies, characterized in that, It includes the following steps: (1) Prepare core-shell Fe3O4@Au nanoparticles, where the size of the Fe3O4 core is 50 - 100 nm and the thickness of the Au shell is 5 - 10 nm; (2) Immobilize alanine dehydrogenase (AlaDH) on the surface of the core-shell Fe3O4@Au nanoparticles to form an enzyme-based biosensing membrane; (3) Mix polyvinyl chloride (PVC), sodium tetraphenylborate (NaTFPB), 2-nitrophenyloctyl ether (NPOE), and nonactin in a mass ratio of 65.6:0.6:131.8:2, and dissolve them in tetrahydrofuran (THF) to prepare an ammonium ion-sensitive membrane solution; (4) Coat the sensitive membrane solution on the surface of a glassy carbon electrode (GCE) modified with Fe3O4@Au / AlaDH, and dry it to form an all-solid-state ammonium ion-selective electrode; (5) Immerse the electrode in the water sample to be measured, measure the potential response by the open-circuit potential method, and calculate the ammonia nitrogen concentration by combining with the standard curve.

2. The rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that, The immobilization method of the alanine dehydrogenase in step (2) is: incubate the Fe3O4@Au nanoparticles with the AlaDH solution at 4 °C for 12 hours, and obtain an enzyme-nanoparticle complex after magnetic separation.

3. The rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that, The preparation method of the core-shell Fe3O4@Au nanoparticles in step (1) includes: (a) Prepare Fe3O4 nanoparticles by the co-precipitation method and perform amination modification; (b) Mix the aminated Fe3O4 nanoparticles with the nanoparticle solution, stir and react for 8 hours to form a core-shell structure.

4. The rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that, The detection linear range of the ammonium ion-sensitive membrane is 10 -1 ~10 -8 M, the detection lower limit is 0.05 mg / L, and the response time is 100 seconds.

5. A rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that, The method for establishing the standard curve in step (5) is: (a) Prepare NH4Cl standard solutions with different concentrations in the range of 10 -1 ~10 -8 M, and adjust the pH of the solution with phosphate buffer solution (PBS) with pH = 7.4; (b) Use the all-solid-state ammonium ion-selective electrode to measure the open-circuit potential of each concentration solution and record the stable potential value; (c) Take the logarithm of the ammonia nitrogen concentration as the abscissa and the potential response value as the ordinate to fit a linear relationship model.

6. The rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that, The signal attenuation rate of the all-solid-state ammonium ion-selective electrode is less than 5% after continuous use for 30 days, and the repeatability error ≤ 3%.

7. The rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that The reference electrode used in the detection method is an Ag / AgCl electrode, which is isolated from the solution to be measured through a salt bridge, and the salt bridge solution is a saturated KCl solution.

8. A rapid detection method for ammonia nitrogen in environmental water bodies according to claim 1, characterized in that, The combination of the enzyme-based biosensor membrane and the ammonium ion sensitive membrane makes the electrode sensitive to NH4 + The selectivity coefficient (K + / NH4 + ) is 0.01, and the interference rate is less than 5%.

9. A rapid detection method for ammonia nitrogen in environmental water bodies according to any one of claims 1-8, characterized in that, It includes: (a) A glassy carbon electrode (GCE) substrate; (b) An Fe3O4@Au / AlaDH modification layer; (c) An ammonium ion-sensitive membrane composed of PVC, NaTFPB, NPOE, and nonactin.

10. A rapid detection method for ammonia nitrogen in environmental water bodies according to claim 9, characterized in that, The thickness of the sensitive membrane is the film formed after drying the coating of 6 μL of the membrane solution.

Images