Method for detecting iodate ions based on Ce-UiO-66-NO2 nano enzyme

Abstract

The invention belongs to the technical field of detection of iodate ions, and provides a method for detecting iodate ions based on Ce-UiO-66-NO2 nano enzyme. Ce-UiO-66-NO2 has good oxide-like enzyme activity and can be used for catalyzing colorless 3, 3 ', 4', 5 '-tetramethyl-3, 4'-biphenyl. According to the present invention, blue oxidation-state TMB is generated from 3, 3 ', 5, 5'-tetramethyl benzidine (TMB), the oxidation-state TMB is reduced in the presence of tin ions so as to light the color of the solution, and the oxidation of the tin ions is promoted in the presence of iodate ions, such that the catalytic activity of the Ce-UiO-66-NO2 nano-enzyme is recovered, and the color of the solution is darkened so as to construct the colorimetric sensor for iodate ion detection, according to the method, the colorimetric rapid detection analysis of the iodate ions in the table salt can be realized without pretreating a detection sample and purchasing expensive instruments, so that the detection efficiency is greatly improved, and the detection cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of iodate ion detection, and in particular to a method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme. Background Art

[0002] Iodine is an essential trace element for the human body. Iodate ions, as an important component of iodine fortifiers, are often added to foods such as table salt to prevent iodine deficiency. However, if the amount of iodate ions added is too high, it may have adverse effects on the human thyroid function; if the amount added is insufficient, the expected iodine supplementation effect cannot be achieved. Therefore, accurate detection of iodate ions in food is a key link in ensuring food safety and meeting the human body's reasonable iodine intake needs. At present, there are many methods for detecting iodate ions. Instrumental analysis methods such as ion chromatography (IC) and high performance liquid chromatography (HPLC) have the advantages of high sensitivity and good accuracy, and can achieve the separation and quantification of iodate ions in complex samples, but these methods often require expensive instruments and equipment, complex sample pre-treatment processes, and take a long time, which makes it difficult to meet the needs of rapid on-site detection.

[0003] Nanozymes are a new type of artificial enzyme that can convert substrates into products under physiological conditions. Compared to natural enzymes, nanozymes have better stability and durability, and their preparation is less cost-effective, which has led to more in-depth research on nanozymes. To date, a variety of nanozymes have been developed, including metal-organic frameworks, metal oxides, precious metals, carbon-based nanomaterials, and so on. These nanozymes have been applied in fields such as environmental analysis and detection, bioanalysis, disease treatment, and antibacterial activity. Ce-UiO-66-NO2 nanozyme belongs to the metal-organic framework (MOF)-based nanozyme. It uses metal cerium (Ce) as the central node and self-assembles with organic ligands through coordination bonds to form a MOF material with a regular pore structure. Ce-UiO-66-NO2 has peroxidase activity, oxidase activity, and catalase activity. Chinese invention patent publication number CN119334931A discloses a uric acid detection material Ce-UiO-66-X based on cerium-based UiO-66, as well as its preparation method and application. The material can be transformed from white to orange-red in the presence of hydrogen peroxide, allowing for rapid quantitative analysis of uric acid concentration.

[0004] At present, there is no report on the use of Ce-UiO-66-NO2 nanozyme to detect iodate ions in table salt. Summary of the Invention

[0005] The object of the present invention is to provide a method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme to address the above-mentioned problems. The present invention has a low detection limit, high selectivity and good stability, and achieves the purpose of rapid and low-cost quantitative detection of iodate ions in table salt.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme, comprising the following steps:

[0008] (1) Solution preparation: Prepare a series of iodate ion standard solutions with concentration gradients; prepare tin ions (Sn 2+ ) standard solution, Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution;

[0009] (2) Drawing of standard curve: Draw a standard solution of iodate ion with a certain concentration and tin ion (Sn 2+ ) standard solution was mixed and reacted for a period of time, and then a certain amount of ABS buffer solution, a certain amount of Ce-UiO-66-NO2 reserve solution and a certain amount of TMB solution were added, and the mixture was shaken evenly to obtain a mixed reagent. The mixed reagent was monitored by ultraviolet spectrophotometer to obtain the absorbance value at 652nm. The absorbance value measured when the concentration of the iodate ion standard solution was 0 was recorded as A o , the absorbance value measured when the concentration of iodate ion is other values ​​is recorded as A n , according to the formula ΔA=A n -A o Calculating the absorbance change ΔA to obtain the absorbance change ΔA of iodate ion standard solutions with different concentrations in the mixed reagent; using iodate ion standard solutions with different concentrations to draw a graph, obtaining a linear standard curve showing how the absorbance change ΔA changes with the concentration of the iodate ion standard solution;

[0010] (3) Sample testing: Replace the iodate ion standard solution with the sample to be tested and mix it with the same tin ion (Sn) solution as in step (2). 2+ ) The standard solution was mixed and reacted for a period of time, and the same ABS buffer solution, Ce-UiO-66-NO2 reserve solution and TMB solution as in step (2) were added and shaken evenly to obtain a mixed reagent. The mixed reagent was shaken evenly to obtain an absorbance value A n , according to ΔA=A n -A o The absorbance change ΔA is calculated, and the iodate ion concentration in the sample to be tested can be obtained according to the linear standard curve.

[0011] In the present invention, preferably, the Ce-UiO-66-NO2 nanozyme is obtained by dissolving nitroterephthalic acid in dimethylformamide, adding ammonium cerium nitrate dropwise, stirring and reacting at 90-100°C, and then centrifuging, washing and drying.

[0012] In the present invention, preferably, the iodate ion standard solution and tin ion (Sn 2+ ) The mixing reaction time of the standard solution is 2 to 6 minutes.

[0013] In the present invention, preferably, the tin ions (Sn 2+ ) standard solution has a concentration of 104 μM and is used in an amount of 10 μL; the concentration of the Ce-UiO-66-NO2 reserve solution is 1 mg / mL and is added in an amount of 25 μL; the concentration of the ABS buffer solution is 0.1 M, the pH value is 3.0-4.0, and is added in an amount of 915 μL; the concentration of the TMB buffer solution is 0.2-0.5 mM and is added in an amount of 40 μL; the amount of the iodate ion standard solution in step (2) and the sample to be tested in step (3) is 10 μL.

[0014] In the present invention, preferably, the Ce-UiO-66-NO2 reserve solution is obtained by dissolving Ce-UiO-66-NO2 nanozyme in ultrapure water.

[0015] In the present invention, preferably, the iodate ion standard solution and tin ion (Sn 2+ ) The mixing reaction time of the standard solution is 4 minutes.

[0016] In the present invention, preferably, the amount of the Ce-UiO-66-NO2 reserve solution in steps (2) and (3) is 25 μL; the concentration of the ABS buffer solution is 0.1 M, and the pH value is 3.0; and the concentration of the TMB buffer solution is 0.4 mM.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. The Ce-UiO-66-NO2 used in the present invention has good oxidase-like activity and can catalyze colorless 3,3',5,5'-tetramethylbenzidine (TMB) to generate blue oxidized TMB. The strong reducing property of tin ions enables it to reduce the oxidized TMB in the presence of tin ions, making the solution color lighter. In the presence of iodate ions, due to the strong oxidizing property of iodate ions, it effectively promotes the oxidation of tin ions, so that the Ce-UiO-66-NO2 nanozyme recovers the catalytic activity and the solution color becomes darker. Thus, a colorimetric sensor is constructed for the detection of iodate ions. This method does not require complex pretreatment of the test sample, nor does it require the purchase of expensive instruments to achieve one-step colorimetric rapid detection and analysis of iodate ions in table salt. The detection time is short, the detection efficiency is greatly improved, and the detection cost is reduced.

[0019] 2. The detection limit of iodate ions in the colorimetric sensing system constructed by the present invention is as low as 0.33 μM, and the detection of iodate ions has good selectivity, stability, and reproducibility. The accuracy of sample detection is high and can be applied to the detection of actual samples. It helps to promptly detect whether the iodate ion content exceeds the standard, and is expected to be used to protect food safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the XRD pattern of Ce-UiO-66-NO2 nanozyme composite material;

[0021] Figure 2 The infrared spectrum of Ce-UiO-66-NO2 nanozyme and its composite material;

[0022] Figure 3 This is the scanning electron microscopy of Ce-UiO-66-NO2 nanozyme;

[0023] Figure 4 Transmission electron microscopy image of Ce-UiO-66-NO2 nanozyme;

[0024] Figure 5 is the typical absorption spectrum of the system in the presence of different concentrations of iodate ions;

[0025] Figure 6 is a linear graph of the change in iodate ion concentration at 652 nm absorbance;

[0026] Figure 7 is the selectivity test result of the reaction system;

[0027] Figure 8 This is the reproducibility test result of Ce-UiO-66-NO2 nanozyme;

[0028] Figure 9These are the stability test results of Ce-UiO-66-NO2 nanozyme. DETAILED DESCRIPTION

[0029] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention. The reagents and instruments used in the embodiments of the present invention can be purchased on the market. Tin ions (Sn 2+ ) standard solution was prepared by adding stannous chloride dihydrate (AR) to deionized water; iodate standard solution was prepared by adding potassium iodate (AR) to deionized water.

[0030] The Ce-UiO-66-NO2 nanozyme used in the present invention was prepared by the following method: 0.6333 g of nitroterephthalic acid was dissolved in 18 mL of dimethylformamide (DMF), followed by the dropwise addition of 6 mL of 0.5 mol / L ceric ammonium nitrate, and the mixture was stirred at 100°C in an oil bath for 15 minutes. Subsequently, the product was collected by centrifugation at 5000 rpm for 3 minutes and washed three times with dimethylformamide and ethanol, respectively. Finally, the collected product was dried in vacuo at 60°C for 12 hours.

[0031] Figure 1 The XRD pattern of Ce-UiO-66-NO2 is consistent with the existing literature. After being immersed in the reaction medium, the Ce-UiO-66-NO2 crystals are still intact, and the XRD signal is consistent with the expected results. The structure of Ce-UiO-66-NO2 was analyzed using Fourier transform infrared spectroscopy, and it was found that the absorption peak at 1526cm belongs to -NO2, such as Figure 2 , it can be verified that there is a nitro functional group on the ligand. In addition, according to Figure 3 and Figure 4 Scanning electron microscopy (SEM, STM) images of Ce-UiO-66-NO2 show a polyhedral structure with a size range of approximately 100 nm. Various characterization techniques confirmed the successful synthesis of Ce-UiO-66-NO2.

[0032] In some specific embodiments of the present invention, the method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme comprises the following steps:

[0033] (1) Solution preparation: Prepare a series of iodate ion standard solutions with a concentration gradient ranging from 0 to 64 μM; prepare tin ions (Sn 2+) standard solution, Ce-UiO-66-NO2 stock solution (dissolved in ultrapure water), ABS buffer solution and TMB solution;

[0034] (2) Drawing of standard curve: Draw a standard solution of iodate ion with a certain concentration and tin ion (Sn 2+ ) standard solution was mixed and reacted for a period of time, and then a certain amount of ABS buffer solution, a certain amount of Ce-UiO-66-NO2 reserve solution and a certain amount of TMB solution were added, and the mixture was shaken evenly to obtain a mixed reagent. The mixed reagent was monitored by ultraviolet spectrophotometer to obtain the absorbance value at 652nm. The absorbance value measured when the concentration of the iodate ion standard solution was 0 was recorded as A o , the absorbance value measured when the concentration of iodate ion is other values ​​is recorded as A n , according to the formula ΔA=A n -A o Calculating the absorbance change ΔA to obtain the absorbance change ΔA of iodate ion standard solutions with different concentrations in the mixed reagent; using iodate ion standard solutions with different concentrations to draw a graph, obtaining a linear standard curve showing how the absorbance change ΔA changes with the concentration of the iodate ion standard solution;

[0035] (3) Sample testing: Replace the iodate ion standard solution with the sample to be tested and mix it with the same tin ion (Sn) solution as in step (2). 2+ ) The standard solution was mixed and reacted for a period of time, and the same ABS buffer solution, Ce-UiO-66-NO2 reserve solution and TMB solution as in step (2) were added and shaken evenly to obtain a mixed reagent. The mixed reagent was shaken evenly to obtain an absorbance value A n , according to ΔA=A n -A o The absorbance change ΔA is calculated, and the iodate ion concentration in the sample to be tested can be obtained according to the linear standard curve.

[0036] Example 1

[0037] The method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme has the following specific steps:

[0038] (1) Solution preparation: Prepare a series of potassium iodate standard solutions with a concentration gradient ranging from 0 to 64 μM; prepare a 104 μM stannous chloride standard solution, a 1 mg / mL Ce-UiO-66-NO2 stock solution, a 0.1 M ABS buffer solution with a pH of 3.5, and a 0.2 mM TMB solution;

[0039] (2) Drawing of the standard curve: 10 μL of 0 μM iodate ion standard solution was mixed with 10 μL of 104 μM stannous chloride standard solution and reacted for 2 min. Then, 915 μL of 0.1 M ABS buffer solution with a pH value of 3.5, 25 μL of 1 mg / mL Ce-UiO-66-NO2 reserve solution and 40 μL of 0.2 mM TMB solution were added and shaken to obtain a mixed reagent. The mixed reagent was monitored by ultraviolet spectrophotometer to obtain the absorbance value at 652 nm. The absorbance value measured when the iodate ion standard solution was 0 μM was recorded as A. o , the absorbance value measured when the concentration of iodate ion is other values ​​is recorded as A n , according to the formula ΔA=A n -A o Calculating the absorbance change ΔA to obtain the absorbance change ΔA of iodate ion standard solutions with different concentrations in the mixed reagent; using iodate ion standard solutions with different concentrations to draw a graph, obtaining a linear standard curve showing how the absorbance change ΔA changes with the concentration of the iodate ion standard solution;

[0040] (3) Sample testing: replace the iodate ion standard solution with the sample to be tested, mix it with the same stannous chloride standard solution as in step (2) and react for 2 minutes, add the same ABS buffer solution, Ce-UiO-66-NO2 reserve solution and TMB solution as in step (2) and shake evenly to obtain a mixed reagent, shake evenly to obtain the mixed reagent, and test to obtain the absorbance value A n , according to ΔA=A n -A o The absorbance change ΔA is calculated, and the iodate ion concentration in the sample to be tested can be obtained according to the linear standard curve.

[0041] Example 2

[0042] The method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme has the following specific steps:

[0043] (1) Solution preparation: Prepare a series of potassium iodate standard solutions with a concentration gradient ranging from 0 to 64 μM; prepare a 104 μM stannous chloride standard solution, a 1 mg / mL Ce-UiO-66-NO2 stock solution, a 0.1 M ABS buffer solution with a pH of 4.0, and a 0.5 mM TMB solution;

[0044] (2) Drawing of the standard curve: 10 μL of 0 μM iodate ion standard solution and 10 μL of 104 μM stannous chloride standard solution were mixed and reacted for 6 min. Then, 910 μL of 0.1 M ABS buffer solution with a pH value of 4.0, 30 μL of 1 mg / mL Ce-UiO-66-NO2 reserve solution and 40 μL of 0.5 mM TMB solution were added. The mixture was shaken to obtain a uniform mixture. The absorbance value at 652 nm was monitored by ultraviolet spectrophotometer. The absorbance value measured when the iodate ion standard solution was 0 μM was recorded as A. o , the absorbance value measured when the concentration of iodate ion is other values ​​is recorded as A n , according to the formula ΔA=A n -A o Calculating the absorbance change ΔA to obtain the absorbance change ΔA of iodate ion standard solutions with different concentrations in the mixed reagent; using iodate ion standard solutions with different concentrations to draw a graph, obtaining a linear standard curve showing how the absorbance change ΔA changes with the concentration of the iodate ion standard solution;

[0045] (3) Sample testing: replace the iodate ion standard solution with the sample to be tested, mix it with the same stannous chloride standard solution as in step (2) and react for 6 minutes, add the same ABS buffer solution, Ce-UiO-66-NO2 reserve solution and TMB solution as in step (2) and shake evenly to obtain a mixed reagent, shake evenly to obtain the mixed reagent, and test to obtain the absorbance value A n , according to ΔA=A n -A o The absorbance change ΔA is calculated, and the iodate ion concentration in the sample to be tested can be obtained according to the linear standard curve.

[0046] Example 3

[0047] The method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme has the following specific steps:

[0048] (1) Solution preparation: Prepare a series of potassium iodate standard solutions with a concentration gradient ranging from 0 to 64 μM; prepare a 104 μM stannous chloride standard solution, a 1 mg / mL Ce-UiO-66-NO2 stock solution, a 0.1 M ABS buffer solution with a pH of 3.0, and a 0.4 mM TMB solution;

[0049] (2) Drawing of the standard curve: 10 μL of 0 μM iodate ion standard solution and 10 μL of 104 μM stannous chloride standard solution were mixed and reacted for 4 min. Then, 915 μL of 0.1 M ABS buffer solution with a pH value of 3.0, 25 μL of 1 mg / mL Ce-UiO-66-NO2 reserve solution and 40 μL of 0.4 mM TMB solution were added. The mixture was shaken to obtain a mixed reagent. The mixed reagent was monitored by ultraviolet spectrophotometer to obtain the absorbance value at 652 nm. The absorbance value measured when the iodate ion standard solution was 0 μM was recorded as A. o , the absorbance value measured when the concentration of iodate ion is other values ​​is recorded as A n , according to the formula ΔA=A n -A o Calculating the absorbance change ΔA to obtain the absorbance change ΔA of iodate ion standard solutions with different concentrations in the mixed reagent; using iodate ion standard solutions with different concentrations to draw a graph, obtaining a linear standard curve showing how the absorbance change ΔA changes with the concentration of the iodate ion standard solution;

[0050] (3) Sample testing: replace the iodate ion standard solution with the sample to be tested, mix it with the same stannous chloride standard solution as in step (2) and react for 4 minutes, add the same ABS buffer solution, Ce-UiO-66-NO2 reserve solution and TMB solution as in step (2) and shake evenly to obtain a mixed reagent, shake evenly to obtain the mixed reagent, and test to obtain the absorbance value A n , according to ΔA=A n -A o The absorbance change ΔA is calculated, and the iodate ion concentration in the sample to be tested can be obtained according to the linear standard curve.

[0051] Under the optimal test conditions of Example 3, the test results are as follows Figures 5-6 When the concentration of iodate ions added increases, the absorbance of the reaction system at 652 nm will increase accordingly. Figure 5 The UV spectra of the reaction system at different iodate ion concentrations and the corresponding color change trend of oxTMB are shown. As the concentration of iodate ions increases from 0μM to 64μM, the absorbance at 652nm increases continuously, and the obvious change of the solution from colorless to blue can be observed with the naked eye. The above phenomenon proves that the addition of iodate ions can enhance the activity of Ce-UiO-66-NO2 type oxide mimic enzymes, and the quantitative detection of iodate ions can be achieved through the absorbance at 652nm. Through the absorbance changes of the reaction system solution at different iodate ion concentrations, the linear equation can be obtained as ΔA=0.0113X+0.2006, R 2=0.9924, the linear range is from 0μM to 64μM, and the detection limit LOD value is 0.33μM. The sensor has a low detection limit and good analytical performance and can be applied to the detection of table salt.

[0052] Selectivity analysis

[0053] Selectivity is an influencing factor that must be considered when designing an excellent analytical sensor system. This experiment was conducted using interfering ions that may exist in table salt. First, 10μL of the sample solution to be tested was mixed with 10μL of a 104μM stannous chloride standard solution for 4 minutes, and then 915μL of a 0.1M, pH 3.0 ABS buffer solution, 40μL of a 0.4mM TMB buffer solution, and 25μL of a 1mg / mL Ce-UiO-66-NO2 reserve solution were added. Different interfering ions were added to each sample to be tested (iodate ions and all other interfering ions were mixed in the mixture). The iodate ion concentration was 64μM, and the interfering ion concentration was ten times the iodate ion concentration (640μM). The test results are shown in Figure 2. Figure 7 It can be seen that only the addition of iodate ions can improve the oxidase-like catalytic activity of the reaction system. Whether calcium ions, cadmium ions, potassium ions, magnesium ions, manganese ions, sodium ions, chloride ions, sulfate ions, carbonate ions, or bromide ions are added, even if the concentration of these interfering ions is ten times that of iodate ions, the absorbance of the reaction system of these interfering ions does not change significantly, indicating that these interfering ions cannot increase the oxidation ability of Ce-UiO-66-NO2 nanozyme on TMB. The colorimetric sensing system of the present invention has high selectivity for iodate ions, which lays a good foundation for its detection in actual samples.

[0054] Reproducibility analysis

[0055] Prepare 5 sets of identical samples for reproducibility testing: 10 μL of 104 μM tin chloride solution, 10 μL of 64 μM potassium iodate solution, reaction time 4 minutes, 915 μL of 0.1 M ABS buffer solution with a pH of 3.5, 40 μL of 0.4 mM TMB buffer solution, and 25 μL of 1 mg / mL Ce-UiO-66-NO2 stock solution. Figure 8 As shown in A 652nm Based on the five sets of absorbance obtained, the reproducibility of Ce-UiO-66-NO2 nanozyme was calculated. The relative standard deviation (RSD) of these five sets of data was about 1.1%, and the experimental results were satisfactory.

[0056] Stability analysis

[0057] In this experiment, the stability of Ce-UiO-66-NO2 nanozyme was also tested. In the experiment, the 1 mg / mL Ce-UiO-66-NO2 nanozyme solution was subjected to colorimetric detection on the 1st, 3rd, 5th, 7th, and 9th days. Figure 9 As shown, the relative standard deviation (RSD) calculated based on its absorbance was 2.6%, which was a satisfactory result, indicating that the Ce-UiO-66-NO2 nanozyme had good stability.

[0058] Actual sample testing

[0059] To evaluate the feasibility of the Ce-UiO-66-NO2 nanozyme-based colorimetric method for detecting iodate ions in real samples, salt solutions were spiked with three different concentrations of iodate ions using the standard addition method. The analytical results are listed in the table below. The iodate ion recoveries ranged from 97.2% to 110%, with relative standard deviations (RSDs) ranging from 0.7% to 1.8% (n=3). This indicates that the Ce-UiO-66-NO2 nanozyme-based colorimetric method is suitable for detecting iodate ions in real samples.

[0060] Table 1 Detection of actual salt samples

[0061]

[0062] The above description is a detailed description of the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for detecting iodate ions based on Ce-UiO-66-NO2 nanozyme, characterized in that: The following steps are involved: (1) Solution preparation: Prepare a series of iodate ion standard solutions with a concentration gradient; Prepare tin ions (Sn 2 + ) standard solution, Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution; (2) Drawing of standard curve: Draw a standard solution of iodate ion with a certain concentration and tin ion (Sn 2+ ) standard solution was mixed and reacted for a period of time, and then a certain amount of ABS buffer solution, a certain amount of Ce-UiO-66-NO2 reserve solution and a certain amount of TMB solution were added, and the mixture was shaken evenly to obtain a mixed reagent. The mixed reagent was monitored by ultraviolet spectrophotometer to obtain the absorbance value at 652nm. The absorbance value measured when the concentration of the iodate ion standard solution was 0 was recorded as A o , the absorbance value measured when the concentration of iodate ion is other values ​​is recorded as A n , according to the formula ΔA=A n -A o Calculating the absorbance change ΔA to obtain the absorbance change ΔA of iodate ion standard solutions with different concentrations in the mixed reagent; using iodate ion standard solutions with different concentrations to draw a graph, obtaining a linear standard curve showing how the absorbance change ΔA changes with the concentration of the iodate ion standard solution; (3) Sample testing: Replace the iodate ion standard solution with the sample to be tested and mix it with the same tin ion (Sn) solution as in step (2). 2+ ) The standard solution was mixed and reacted for a period of time, and the same ABS buffer solution, Ce-UiO-66-NO2 reserve solution and TMB solution as in step (2) were added and shaken evenly to obtain a mixed reagent. The mixed reagent was shaken evenly to obtain an absorbance value A n , according to ΔA=A n -A o The absorbance change ΔA is calculated, and the iodate ion concentration in the sample to be tested can be obtained according to the linear standard curve.

2. The method for detecting iodate ions according to claim 1, wherein: The Ce-UiO-66-NO2 nanozyme is obtained by dissolving nitroterephthalic acid in dimethylformamide, adding cerium ammonium nitrate dropwise, stirring and reacting at 90-100°C, and then centrifuging, washing and drying.

3. The method for detecting iodate ions according to claim 1, wherein: The iodate ion standard solution and tin ion (Sn 2+ ) The mixing reaction time of the standard solution is 2 to 6 minutes.

4. The method for detecting iodate ions according to claim 1, wherein: The tin ions (Sn 2+ ) standard solution has a concentration of 104 μM and is used in an amount of 10 μL; the concentration of the Ce-UiO-66-NO2 reserve solution is 1 mg / mL and is added in an amount of 25 to 30 μL; the concentration of the ABS buffer solution is 0.1 M, the pH value is 3.0 to 4.0, and is added in an amount of 915 μL; the concentration of the TMB buffer solution is 0.2 to 0.5 mM and is added in an amount of 40 μL; the amount of the iodate ion standard solution in step (2) and the sample to be tested in step (3) is 10 μL.

5. The method for detecting iodate ions according to claim 2, wherein: The Ce-UiO-66-NO2 reserve solution is obtained by dissolving Ce-UiO-66-NO2 nanoenzyme in ultrapure water.

6. The method for detecting iodate ions according to claim 4, wherein: The iodate ion standard solution and tin ion (Sn 2+ ) The mixing reaction time of the standard solution is 4 minutes.

7. The method for detecting iodate ions according to claim 4, wherein: The pH value of the ABS buffer solution in steps (2) and (3) is 3.0; the concentration of the TMB buffer solution is 0.4 mM.

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