A sensor preparation method for nitrite detection and application

Abstract

The application discloses a sensor preparation method for nitrite detection and application, and the method comprises the following steps: annealing an indium oxide precursor to obtain indium oxide particles, and then compounding the indium oxide particles with gold nanoparticles to obtain gold-indium oxide nanocomposites. The gold-indium oxide nanocomposites are dispersed in an ethanol solution, ultrapure water and a Nafion solution to prepare a suspension of the gold-indium oxide nanocomposites, and the suspension is dripped on a glassy carbon electrode by using a pipette gun. The electrode is dried to be ready for electrochemical test. The sensor prepared by the method can realize rapid and accurate detection of nitrite in aquaculture, has high sensitivity, selectivity and anti-interference, and overcomes the defects of high price, long time and complex operation of traditional detection methods, and has certain guiding and reference significance for the aquaculture industry.

Description

Technical Field

[0001] This invention relates to the field of electrochemical sensor technology, specifically to a method for preparing and applying a sensor for nitrite detection. Background Technology

[0002] Nitrite, a highly toxic inorganic pollutant, is widely distributed in industry, agriculture, the environment, food, and even physiological systems. However, its excessive presence poses serious threats to public health and the ecological environment. Short-term inhalation of small amounts of nitrite may trigger acute poisoning, while long-term intake can lead to various diseases, including potential carcinogenic risks. High concentrations of nitrite not only harm aquatic organisms and cause economic losses in aquaculture but also pose a persistent chronic threat to human health. Therefore, developing an efficient, accurate, economical, and sensitive sensing technology suitable for nitrite detection in aquaculture is of significant practical importance for both human health and environmental monitoring.

[0003] To date, the main methods for detecting nitrite include ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, chemiluminescence spectroscopy, electrochemical spectroscopy, and chromatography. However, these processes often require expensive equipment, incur high costs, or involve cumbersome processing procedures, hindering their practical application. Electrochemical sensors, with their advantages of high sensitivity, low cost, fast response, portability, and feasibility of on-site analysis, have been widely used in environmental monitoring and other fields. This invention is based on a noble metal-modified metal oxide semiconductor-based electrochemical sensor, achieving highly sensitive detection of nitrite. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a sensor for nitrite detection, so as to solve the problems mentioned above.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a sensor for nitrite detection includes the following steps:

[0007] S1: Mix terephthalic acid and indium nitrate tetrahydrate with deionized water to obtain mixed solution A. Soak mixed solution A in a water bath and sonicate it. Then stir it with a magnetic stirrer for 30-60 minutes. Then transfer mixed solution A to a steel autoclave lined with polytetrafluoroethylene and place it in an oven to react for 4-6 hours.

[0008] S2: Remove the supernatant from the mixed solution A, wash with ethanol and sonicate, then centrifuge in a high-speed centrifuge, and dry the mixture after removing the supernatant in an oven for 6-12 hours to obtain the indium oxide particle precursor.

[0009] S3: High-temperature annealing treatment of indium oxide particle precursor to obtain indium oxide nanoparticles;

[0010] S4: The aqueous solution of HAuCl4, indium oxide nanoparticles and reducing agent (NH4)2CO3 solution were mixed and stirred for 2 hours. After centrifugation, the composite product was separated from the solution and washed with ultrapure water. Then, it was dried in an oven for 3-6 hours to obtain the gold-indium oxide nanocomposite.

[0011] S5: Take the glassy carbon electrode and polish it with alumina powder, then rinse it with deionized water;

[0012] The gold-indium oxide nanocomposite prepared in S4 was dispersed in ethanol solution, ultrapure water and Nafion solution to prepare an aqueous suspension of the gold-indium oxide nanocomposite;

[0013] 10 μL of gold-indium oxide nanocomposite suspension was dropped onto the surface of a glassy carbon electrode and dried to obtain a composite glassy carbon electrode.

[0014] S6: Using the composite glassy carbon electrode prepared in S5 as the working electrode, the platinum wire electrode as the counter electrode, and the silver / silver chloride electrode as the reference electrode, a sensor for nitrite detection is prepared.

[0015] As a further aspect of the present invention: in S2, the mass fraction of ethanol is 99.7%, and the drying temperature in the oven is 60°C.

[0016] As a further aspect of the present invention: in step S3, the indium oxide particle precursor is placed in an annealing furnace at 500°C and reacted in an air atmosphere for 2 hours, with a heating rate of 5°C / min.

[0017] As a further aspect of the present invention: in S5, the diameter of the alumina powder is 0.05 μm.

[0018] As a further aspect of the present invention: an application of a nitrite detection sensor, characterized in that the sensor is prepared using the preparation method described above;

[0019] Includes the following steps:

[0020] Q1: Determine the optimal pH value for sensor detection:

[0021] Phosphate buffer solutions with different pH values ​​but the same concentration were prepared, and a 0.5M nitrite solution was also prepared. The sensor prepared in S6 was used to test the response of nitrite concentration to current at different pH values. The corresponding nitrite current was measured in phosphate buffer solutions with different pH values ​​using cyclic voltammetry. By comparing the peak current values, the pH value corresponding to the maximum peak current value was found, and the optimal pH range of the buffer solution for sensor detection was determined to be 7.36-7.4.

[0022] Q2: Detection of nitrite concentration:

[0023] Based on the optimal pH range of 7.36-7.4 obtained in Q1, phosphate buffer solution was prepared as the electrolyte; nitrite solutions of different concentrations were prepared, ranging from 10 to 5000 μmol·L⁻¹. -1 The peak current values ​​corresponding to different concentrations of nitrite solutions were measured using the differential pulse voltammetry method with the sensor prepared in S6. The functional relationship between nitrite concentration and peak current was calculated, and a linear relationship graph between peak current and nitrite concentration was plotted. Nitrite in aquaculture was detected using an electrochemical sensor, and the peak current value was obtained. The concentration of nitrite in aquaculture was calculated using the obtained linear relationship graph.

[0024] As a further aspect of the present invention: the concentration of the phosphate buffer solution in Q1 is 0.1M.

[0025] As a further aspect of the present invention: the optimal pH value determined in Q1 is used to prepare a phosphate buffer solution for detecting nitrite solutions of different concentrations.

[0026] The beneficial effects of this invention are:

[0027] (1) In this invention, the prepared nitrite electrochemical sensor can be directly used to detect nitrite in aquaculture, providing effective reference and guidance for aquaculture. Furthermore, the prepared glassy carbon electrode has a gold-indium oxide nanocomposite surface, which... Figure 2 and Figure 3 It can be seen that the material of this sensor, due to the loading of gold nanoparticles, has unique conductivity and chemical stability, and the surface area is increased. During the detection process, the contact area between the detection material and the test solution is increased, which effectively enhances the enrichment of nitrite on the surface of the working electrode, giving it a positive effect on electrocatalytic performance and facilitating the monitoring of nitrite.

[0028] In the process of sensor fabrication, only ordinary instruments are needed, the process cost is low, and the fabrication method is simple and easy to operate;

[0029] (2) Correspond the obtained peak current values ​​to the nitrite ion concentrations one-to-one, calculate the functional relationship between nitrite concentration and peak current, and plot the linear relationship between peak current and nitrite ion concentration. The results are as follows: Figure 5 As shown, the linear detection range of this sensor for nitrite is 10-500 μmol·L⁻¹. -1 and 500-5000 μmol·L -1 The regression equations are I1(μA)=0.0097C1(μmol)+5.24(R) 2 =0.995) and I2(μA)=0.014C2(μmol)+2.23(R 2 =0.998). Then, an electrochemical sensor was used to detect nitrite in aquaculture, and the peak current value was obtained. Using the linear relationship between the peak current and the nitrite ion concentration, the concentration of nitrite in the sample can be calculated.

[0030] The linear regression equation of this sensor was calculated, proving its detection accuracy in nitrite detection in aquaculture. It has broad prospects and can effectively monitor the concentration of nitrite in aquaculture waters, providing important reference and guidance for the aquaculture industry. Attached Figure Description

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] Figure 1 These are XRD images of the gold-indium oxide nanocomposite prepared in this invention;

[0033] Figure 2 These are scanning electron microscope images of the gold-indium oxide nanocomposite prepared in this invention. Figure 2 Images (a) and (b) in the middle are scanning electron microscope (SEM) images of the indium oxide precursor and indium oxide nanoparticles, respectively. Figure 2 Images (c) and (d) are scanning electron microscope (SEM) images of the gold-indium oxide nanocomposite.

[0034] Figure 3 These are transmission electron microscope (TEM) images of the gold-indium oxide nanocomposite prepared according to this invention. Figure 3 Images (a) and (b) are transmission electron microscopy (TEM) images of the gold-indium oxide nanocomposite.

[0035] Figure 4 The cyclic voltammetry curves of (a) bare glassy carbon electrode, (b) indium oxide modified electrode, and (c) gold-indium oxide nanocomposite modified electrode prepared in this invention in phosphate buffer solution (0.1 mol / L, pH 7.38) containing 5 mmol / L sodium nitrite.

[0036] Figure 5 This is a linear relationship between the sodium nitrite concentration and the oxidation peak current of the gold-indium oxide nanocomposite prepared in this invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Indium oxide (In₂O₃), as an important wide-bandgap N-type semiconductor material, has been extensively studied due to its superior optical and electrical properties and high stability. However, In₂O₃, with its relatively low specific surface area, does not exhibit sufficient conductivity and electrochemical sensing characteristics. Therefore, doping, pore formation, or surface modification of In₂O₃ are employed to improve its conductivity and electrochemical sensing properties. Studies have shown that gold nanoparticles (AuNPs), as a typical noble metal catalyst, possess good conductivity and exhibit strong catalytic activity for the oxidation of nitrite.

[0039] Based on the above description, the present invention aims to provide a method for preparing a sensor for the detection of nitrite in aquaculture.

[0040] The objective of this invention is achieved through the following technical solution:

[0041] To more clearly demonstrate the technical solution and its effects provided by the present invention, the preparation and application of the sensor for nitrite detection in aquaculture provided by the present invention will be described in detail below with specific embodiments.

[0042] Example 1

[0043] This invention relates to a method for preparing a sensor for nitrite detection, comprising:

[0044] Preparation of indium oxide nanoparticles:

[0045] Step A: Weigh 0.18g of terephthalic acid (C8H6O4), 0.468g of indium nitrate tetrahydrate (In(NO3)3·4H2O), and mix with 30.0mL of deionized water to obtain mixed solution A. Place the above mixed solution A in a water bath at about 20°C and sonicate for 10min. Then place it in a magnetic stirrer and stir continuously for 30min at a speed of 800r / min. After the above solution is mixed evenly, transfer the mixed solution to a steel autoclave (50mL) lined with polytetrafluoroethylene and place it in an oven at 80°C to react for 4h.

[0046] Step B: Remove the supernatant from the above mixed solution A, wash the remaining mixture in the above mixed solution A with 30 mL of 99.7% ethanol, sonicate for 10 min until evenly dispersed, centrifuge at 6000 r / min for 5 min, repeat the above washing and centrifugation process 3 times, and then place the mixture after removing the supernatant in a 60℃ oven to dry for 6 h, thereby obtaining the indium oxide particle precursor;

[0047] Step C: The indium oxide particle precursor obtained by drying is annealed in air at 500℃ for 6-8 hours with a heating rate of 5℃ / min to obtain indium oxide nanoparticles.

[0048] Preparation of gold-indium oxide nanocomposites: Refer to Figures 1-3 As shown;

[0049] Step D: First, take 25-100 mg of the prepared In2O3, soak it in ultrapure water and stir for 15 min, then mix it with 1 M (NH4)2CO3, then add a certain concentration of HAuCl4 aqueous solution, stir on a magnetic stirrer for 2 h, centrifuge the product, wash it several times with ultrapure water, and dry it at 60℃ for 4 h to prepare the gold-indium oxide nanocomposite.

[0050] Modification of glassy carbon electrodes:

[0051] Step E: Modify the glassy carbon electrode. Specifically, polish the GCE with alumina powder with a diameter of 0.05 μm to obtain a mirror-like surface, and then rinse with deionized water; disperse the above gold-indium oxide composite in ethanol solution, ultrapure water and Nafion solution to prepare an aqueous suspension of the gold-indium oxide composite.

[0052] Take 10 μL from the above gold-indium oxide nanocomposite suspension, add it dropwise to the surface of a 4 mm glassy carbon electrode in two portions, and dry it. After drying, wait for use in electrochemical testing. In this step, Au, In2O3 and GCE composite materials are all existing materials; GCE is a glassy carbon electrode.

[0053] Sensor fabrication:

[0054] Step F: The sensor adopts a three-electrode system, with the composite glassy carbon electrode obtained in step E as the working electrode, the platinum wire electrode as the counter electrode, and the silver electrode as the reference electrode, to obtain an electrochemical sensor for nitrite detection.

[0055] Example 2

[0056] Preparation of indium oxide nanoparticles:

[0057] Step A: Weigh 0.54 g of terephthalic acid (C8H6O4), 1.404 g of indium nitrate tetrahydrate (In(NO3)3·4H2O), and mix with 30.0 mL of deionized water to obtain mixed solution A. Place the above mixed solution A in a water bath at about 20°C and sonicate for 60 min. Then place it in a magnetic stirrer and stir continuously for 60 min at a speed of 800 r / min. After the above solution is mixed evenly, transfer the mixed solution to a steel autoclave (50 mL) lined with polytetrafluoroethylene and place it in an oven at 120°C to react for 6 h.

[0058] Step B: Remove the supernatant from the above mixed solution A, wash the remaining mixture in the above mixed solution A with 80 mL of 99.7% ethanol, sonicate for 30 min until evenly dispersed, centrifuge at 10000 r / min for 10 min, repeat the above washing and centrifugation process 3 times, and then place the mixture after removing the supernatant in a 60℃ oven to dry for 12 h, thereby obtaining the indium oxide particle precursor;

[0059] Step C: The indium oxide particle precursor obtained by drying is annealed in air at 600℃ for 8 hours with a heating rate of 5℃ / min to obtain indium oxide nanoparticles.

[0060] Preparation of gold-indium oxide nanocomposites:

[0061] Step D: First, take 100 mg of the prepared In2O3, soak it in ultrapure water and stir for 30 min, then mix it with 1 M (NH4)2CO3, then add a certain concentration of HAuCl4 aqueous solution, stir on a magnetic stirrer for 3 h, centrifuge the product, wash it several times with ultrapure water, and dry it at 80℃ for 6 h to prepare the gold-indium oxide nanocomposite.

[0062] Modification of glassy carbon electrodes:

[0063] Step E: Modify the glassy carbon electrode. Specifically, polish the GCE with alumina powder with a diameter of 0.05 μm to obtain a mirror-like surface, and then rinse with deionized water; disperse the above gold-indium oxide composite in ethanol solution, ultrapure water and Nafion solution to prepare an aqueous suspension of the gold-indium oxide composite.

[0064] Take 10 μL from the above gold-indium oxide nanocomposite suspension, add it dropwise to the surface of a 4 mm glassy carbon electrode in two portions, and dry it. After drying, wait for use in electrochemical testing. In this step, Au, In2O3 and GCE composite materials are all existing materials; GCE is a glassy carbon electrode.

[0065] Sensor fabrication:

[0066] Step F: The sensor adopts a three-electrode system, with the composite glassy carbon electrode obtained in step E as the working electrode, the platinum wire electrode as the counter electrode, and the silver chloride electrode as the reference electrode, to obtain an electrochemical sensor for nitrite detection.

[0067] In this invention, the prepared nitrite electrochemical sensor can be directly used to detect nitrite in aquaculture, providing effective reference and guidance for aquaculture. Furthermore, the prepared glassy carbon electrode has a gold-indium oxide nanocomposite surface, which... Figure 2 and Figure 3 It can be seen that the sensor material, due to the loading of gold nanoparticles, has unique conductivity and chemical stability, and the increased surface area increases the contact area between the detection material and the test solution during the detection process, effectively enhancing the enrichment of nitrite on the working electrode surface, giving it a positive effect on electrocatalytic performance, and is beneficial for the monitoring of nitrite.

[0068] In the process of sensor fabrication, only ordinary instruments are needed, the process cost is low, and the fabrication method is simple and easy to operate.

[0069] Regarding the nitrite detection sensor prepared above, the following examples are provided for its application:

[0070] Example 3

[0071] Step W1: Determine the optimal pH value for sensor detection;

[0072] A phosphate buffer solution with a pH of 5.60 and a concentration of 0.1 M was prepared, and a nitrite solution with a concentration of 0.5 M was also prepared. The three-electrode sensor system prepared in the above example was used to conduct experiments to detect the response of nitrite concentration to current at different pH values. In phosphate buffer solutions with different pH values, the corresponding nitrite current was measured by cyclic pulse voltammetry. By comparing the peak current magnitudes, the pH value corresponding to the maximum peak current value could be determined, thus establishing the optimal pH value of the buffer solution for sensor detection as 7.38.

[0073] Step W2: Detect the nitrite concentration;

[0074] Different concentrations of nitrite solutions were prepared, and a phosphate buffer solution with a pH of 7.38 was prepared as the supporting electrolyte. The three electrodes were then placed in these nitrite solutions. The current response caused by nitrite at different concentrations was measured using differential pulse voltammetry. Wastewater from aquaculture was collected, and the working electrodes were placed in each solution. Cyclic voltammetry was used to obtain the corresponding peak current values. The above steps were repeated three times, and the average value was taken.

[0075] The obtained peak current values ​​and nitrite ion concentrations were correlated one-to-one, and the functional relationship between nitrite concentration and peak current was calculated. A linear relationship graph between peak current and nitrite ion concentration was then plotted. The results are as follows: Figure 5 As shown, the linear detection range of this sensor for nitrite is 10-500 μmol·L⁻¹. -1 and 500-5000 μmol·L -1 The regression equations are I1(μA)=0.0097C1(μmol)+5.24(R) 2 =0.995) and I2(μA)=0.014C2(μmol)+2.23(R 2 =0.998). Then, an electrochemical sensor was used to detect nitrite in aquaculture, and the peak current value was obtained. Using the linear relationship between the peak current and the nitrite ion concentration, the concentration of nitrite in the sample can be calculated.

[0076] The linear regression equation of this sensor was calculated, proving the detection accuracy of the nitrite detection sensor used in aquaculture.

[0077] Example 4

[0078] Step W1: Determine the optimal pH value for sensor detection;

[0079] A phosphate buffer solution with a pH of 8.01 and a concentration of 0.1 M was prepared, and a nitrite solution with a concentration of 0.5 M was also prepared. The three-electrode sensor system prepared in the above example was used to conduct experiments to detect the response of nitrite concentration to current at different pH values. In phosphate buffer solutions with different pH values, the corresponding nitrite current was measured by cyclic voltammetry. By comparing the peak current values, the pH value corresponding to the maximum peak current value could be determined, thus establishing the optimal pH value of the buffer solution for sensor detection as 7.38.

[0080] Step W2: Detect the nitrite concentration;

[0081] Nitrite solutions of different concentrations were prepared, and phosphate buffer solution under the same conditions was prepared as the supporting electrolyte. The three electrodes were then placed in these nitrite solutions. The current response caused by nitrite at different concentrations was measured using differential pulse voltammetry. Wastewater from aquaculture was collected, and the working electrodes were placed in each solution. The corresponding peak current values ​​were obtained using differential pulse voltammetry. This process was repeated three times, and the average value was taken.

[0082] The obtained peak current values ​​and nitrite ion concentrations were correlated one-to-one, and the functional relationship between nitrite concentration and peak current was calculated. A linear relationship graph between peak current and nitrite ion concentration was then plotted. The results are as follows: Figure 5 As shown, the linear detection range of this sensor for nitrite is 10-500 μmol·L⁻¹. -1 and 500-5000 μmol·L -1 The regression equations are I1(μA)=0.0097C1(μmol)+5.24(R) 2 =0.995) and I2(μA)=0.014C2(μmol)+2.23(R 2 =0.998). Then, an electrochemical sensor was used to detect nitrite in aquaculture, and the peak current value was obtained. Using the linear relationship between the peak current and the nitrite ion concentration, the concentration of nitrite in the sample can be calculated.

[0083] The linear regression equation of this sensor was calculated, proving the detection accuracy of the nitrite detection sensor used in aquaculture.

[0084] Experimental results show that the sensor has a significant catalytic effect on nitrite, with high sensitivity and fast response. It overcomes the shortcomings of traditional detection methods, such as high cost, long processing time, and complex operation. Therefore, it has certain guiding and reference value for the aquaculture industry, and its application in aquaculture has broad prospects. It can effectively monitor the concentration of nitrite in aquaculture waters, providing important reference and guidance for the aquaculture industry.

[0085] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing a sensor for nitrite detection, characterized in that, Includes the following steps: S1: Mix terephthalic acid and indium nitrate tetrahydrate with deionized water to obtain mixed solution A. Soak mixed solution A in a water bath and sonicate it. Then stir it with a magnetic stirrer for 30-60 minutes. Then transfer mixed solution A to a steel autoclave lined with polytetrafluoroethylene and place it in an oven to react for 4-6 hours. S2: Remove the supernatant from the mixture after the reaction, wash with ethanol and sonicate, then centrifuge in a high-speed centrifuge, and dry the mixture after removing the supernatant in an oven for 6-12 h to obtain indium oxide particle precursor. S3: High-temperature annealing treatment of indium oxide particle precursor to obtain indium oxide nanoparticles; S4: The aqueous solution of HAuCl4, indium oxide nanoparticles and reducing agent (NH4)2CO3 solution were mixed and stirred for 2 hours. After centrifugation, the composite product was separated from the solution and washed with ultrapure water. Then, it was dried in an oven for 3-6 hours to obtain the gold-indium oxide nanocomposite. S5: Take the glassy carbon electrode and polish it with alumina powder, then rinse it with deionized water; The gold-indium oxide nanocomposite prepared in S4 was dispersed in ethanol solution, ultrapure water and Nafion solution to prepare an aqueous suspension of the gold-indium oxide nanocomposite; 10 μL of gold-indium oxide nanocomposite suspension was dropped onto the surface of a glassy carbon electrode and dried to obtain a composite glassy carbon electrode. S6: Using the composite glassy carbon electrode prepared in S5 as the working electrode, the platinum wire electrode as the counter electrode, and the silver / silver chloride electrode as the reference electrode, an electrochemical sensor for nitrite detection is prepared.

2. The method for preparing a nitrite detection sensor according to claim 1, characterized in that, In S2, the mass fraction of ethanol is 99.7%, and the drying temperature in the oven is 60°C.

3. The method for preparing a nitrite detection sensor according to claim 1, characterized in that, In step S3, the indium oxide particle precursor is placed in an annealing furnace at 500°C and reacted in air atmosphere for 2 hours, with a heating rate of 5°C / min.

4. The method for preparing a nitrite detection sensor according to claim 1, characterized in that, In S5, the diameter of the alumina powder is 0.05 μm.

5. A sensor for detecting nitrite, characterized in that, It is prepared by the preparation method described in any one of claims 1-4.

6. The application of the nitrite detection sensor according to claim 5, characterized in that, Includes the following steps: Q1: Determine the optimal pH value for sensor detection: Phosphate buffer solutions with different pH values ​​but the same concentration were prepared, and a 0.5M nitrite solution was also prepared. The sensor prepared in S6 was used to conduct experiments to detect the response of nitrite concentration to current at different pH values. The corresponding nitrite current was measured in phosphate buffer solutions with different pH values ​​using cyclic voltammetry. By comparing the peak current values, the pH value corresponding to the maximum peak current value was found, and the pH range of the buffer solution for sensor detection was determined to be 7.36-7.

4. Q2: Detection of nitrite concentration: Based on the pH range of 7.36-7.4 obtained in Q1, phosphate buffer solution was prepared as the electrolyte; nitrite solutions of different concentrations were prepared, ranging from 10 to 5000 μmol·L⁻¹. -1 ; The peak current values ​​corresponding to different concentrations of nitrite solutions were measured using the differential pulse voltammetry with the sensor prepared in S6. The functional relationship between nitrite concentration and peak current was calculated, and a linear relationship graph between peak current and nitrite concentration was plotted. Nitrite in aquaculture was detected using an electrochemical sensor, and the peak current value was obtained. The concentration of nitrite in aquaculture was calculated using the obtained linear relationship graph.

7. The application of the nitrite detection sensor according to claim 6, characterized in that, The concentration of the phosphate buffer solution in Q1 is 0.1M.

8. The application of the nitrite detection sensor according to claim 6, characterized in that, Phosphate buffer solutions were prepared within the pH range determined in Q1 to detect nitrite solutions of different concentrations.

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