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

Abstract

The invention belongs to the technical field of tin ion detection, and provides a method for detecting tin ions based on Ce-UiO-66-NO2 nano enzyme. The method comprises the following steps: mixing Ce-UiO-66-NO2 nano-enzyme with colorless 3, 3 ', 5, 5'-tetramethyl benzidine (TMB) to generate blue oxidation-state TMB, then adding a sample containing tin ions (Sn < 2 + >), and reducing the oxidation-state TMB by utilizing the strong reducibility of the tin ions (Sn < 2 + >), so that the color of the solution becomes light; the tin ions (Sn < 2 + >) are qualitatively detected according to color change, or the tin ions (Sn < 2 + >) are quantitatively detected by utilizing a linear relation between the change of the absorbance value of the solution before and after the tin ions (Sn < 2 + >) are added and the concentration of the tin ions (Sn < 2 + >). The method has the advantages of low detection limit, high selectivity and good stability, and realizes the purpose of rapid detection of tin ions in tap water.

Description

Technical Field

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

[0002] Heavy metal ions pose a significant threat to the environment and human health. Tin is a common heavy metal in our daily lives and is widely used. The presence of tin ions in tap water can have a wide range of impacts on water quality and human health. High concentrations of tin ions can affect the normal respiratory and digestive systems and even damage human DNA. To ensure the safety and sanitation of tap water, strict control of tin ion content in tap water is necessary, along with strengthened water source protection and water quality monitoring. The current Chinese standard GB / T 5750-2023, "Standard Test Method for Drinking Water," primarily uses atomic absorption spectroscopy and spectrophotometry for the detection of tin (Sn). These methods suffer from cumbersome pretreatment, with some requiring digestion, filtration, and masking steps, increasing the risk of human error. Some methods, such as FAAS and HG-AFS, require specialized training, requiring proficiency in instrument operation and maintenance.

[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 tin ions in tap water. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for detecting tin ions based on Ce-UiO-66-NO2 nanozyme in order to solve the above problems. The method has a low detection limit, high selectivity and good stability, and can realize the rapid quantitative detection of tin ions (Sn 2+ ) purpose.

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

[0007] A method for detecting tin ions based on Ce-UiO-66-NO2 nanozyme is provided. The method comprises mixing a Ce-UiO-66-NO2 nanozyme solution with a colorless 3,3',5,5'-tetramethylbenzidine (TMB) buffer solution to generate a blue oxidized TMB, and then adding a tin ion (Sn 2+ ) samples, using tin ions (Sn 2+ ) reduces the oxidized TMB, which makes the solution lighter in color; according to the color change, the tin ion (Sn 2+ ) for qualitative detection, or by adding tin ions (Sn 2+ ) and the changes in the absorbance of the solution before and after tin ions (Sn 2+ ) concentration to achieve a linear relationship between the tin ion (Sn 2+ ) quantitative detection.

[0008] In the present invention, preferably, the specific steps of the quantitative detection are:

[0009] (1) Solution preparation: Prepare a series of tin ion (Sn 2+ ) standard solution; and prepare Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution;

[0010] (2) Drawing of standard curve: Draw a certain concentration of tin ions (Sn 2+ ) standard solution was added to the cuvette, 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 an ultraviolet spectrophotometer to obtain the absorbance value at 652nm, and the tin ion (Sn 2+ ) The absorbance value measured when the concentration of the standard solution is 0 is recorded as A o , the tin ions (Sn 2+ ) When the concentration of the standard solution is other values, the absorbance value measured is recorded as A n , according to the formula ΔA=A o -A n Calculate the absorbance change ΔA to obtain the different concentrations of tin ions (Sn 2+) standard solution in the mixed reagent absorbance value change value ΔA; using different concentrations of tin ions (Sn 2+ ) standard solution and obtain the absorbance change ΔA with the change of tin ions (Sn 2+ ) a linear standard curve that varies with the concentration of the standard solution;

[0011] (3) Sample testing: Use the sample to be tested to replace the tin ion (Sn 2+ ) standard solution, the same Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution as in step (2) were shaken evenly to obtain a mixed reagent, and the absorbance value A was obtained by testing. n Calculate the absorbance change ΔA and obtain the tin ion (Sn 2+ )concentration.

[0012] 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.

[0013] In the present invention, preferably, the concentration of the Ce-UiO-66-NO2 reserve solution in steps (2) and (3) is 1 mg / mL, and the amount added is 25 μL; the concentration of the ABS buffer solution is 0.1 M, the pH value is 3.0-4.0, and the amount added is 925 μL; the concentration of the TMB buffer solution is 0.2-0.5 mM, and the amount added is 40 μL; the amount added of the tin 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 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.

[0016] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0017] 1. The present invention utilizes the good oxidase-like activity of Ce-UiO-66-NO2, which 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. This law is used to construct a signal attenuation type colorimetric sensor for tin ions (Sn2+ ) detection, this method does not require complicated pretreatment of the test samples, nor does it require the purchase of expensive instruments to achieve one-step colorimetric rapid detection and analysis of tin ions in tap water. The detection time only takes a few minutes, which greatly improves the detection efficiency and reduces the detection cost.

[0018] 2. Tin ions (Sn 2+ ) was detected as low as 0.33 μM, and the detection limit for tin ions (Sn 2+ ) detection has good selectivity, stability, and reproducibility, and has high accuracy in sample detection. It can be applied to the detection of actual samples and helps to timely detect tin ions (Sn 2+ ) content exceeds the standard, and is expected to be used to protect environmental safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the XRD pattern of Ce-UiO-66-NO2 nanozyme composite material;

[0020] Figure 2 The infrared spectrum of Ce-UiO-66-NO2 nanozyme and its composite material;

[0021] Figure 3 This is the scanning electron microscopy of Ce-UiO-66-NO2 nanozyme;

[0022] Figure 4 Transmission electron microscopy image of Ce-UiO-66-NO2 nanozyme;

[0023] Figure 5 For different concentrations of Sn 2+ Typical absorption spectrum of the system when it exists;

[0024] Figure 6 The absorbance at 652 nm changes with Sn 2+ Linear plot of concentration changes;

[0025] Figure 7 The results of the selectivity study of the reaction system;

[0026] Figure 8 This is the reproducibility test result of Ce-UiO-66-NO2 nanozyme;

[0027] Figure 9 These are the stability test results of Ce-UiO-66-NO2 nanozyme. DETAILED DESCRIPTION

[0028] 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+ ) The standard solution was prepared by adding stannous chloride dihydrate (AR) to deionized water.

[0029] 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), and then 6 mL of 0.5 mol / L ceric ammonium nitrate was added dropwise. 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 degrees Celsius for 12 hours.

[0030] 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 , the presence of nitro functional groups on the ligand can be verified. 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.

[0031] The present invention provides a method for detecting tin ions based on Ce-UiO-66-NO2 nanozyme, which comprises mixing a Ce-UiO-66-NO2 nanozyme reserve solution with a colorless 3,3',5,5'-tetramethylbenzidine (TMB) buffer solution to generate a blue oxidized TMB, and then adding a tin ion (Sn 2+ ) samples, using tin ions (Sn 2+ ) can reduce the oxidized TMB, thus making the solution lighter in color. 2+ ) and the changes in the absorbance of the solution before and after tin ions (Sn 2+ ) concentration to achieve a linear relationship between the tin ion (Sn 2+ ) detection.

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

[0033] (1) Solution preparation: Prepare a series of tin ion (Sn 2+ ) standard solution with a concentration range of 0-μM to 128 μM; and prepare Ce-UiO-66-NO2 stock solution (dissolved in ultrapure water), ABS buffer solution and TMB solution;

[0034] (2) Drawing of standard curve: Draw a certain concentration of tin ions (Sn 2+ ) standard solution was added to the cuvette, 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 an ultraviolet spectrophotometer to obtain the absorbance value at 652nm, and the tin ion (Sn 2+ ) The absorbance value measured when the concentration of the standard solution is 0 is recorded as A o , the tin ions (Sn 2+ ) When the concentration of the standard solution is other values, the absorbance value measured is recorded as A n , according to the formula ΔA=A o -A n Calculate the absorbance change ΔA to obtain the different concentrations of tin ions (Sn 2+ ) standard solution in the mixed reagent absorbance value change value ΔA; using different concentrations of tin ions (Sn 2+ ) standard solution and obtain the absorbance change ΔA with the change of tin ions (Sn 2+ ) a linear standard curve that varies with the concentration of the standard solution;

[0035] (3) Sample testing: Use the sample to be tested to replace the tin ion (Sn 2+ ) standard solution, the same Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution as in step (2) were shaken evenly to obtain a mixed reagent, and the absorbance value A was measured. n , calculate the absorbance change ΔA=A o -A n According to the linear standard curve, the tin ion (Sn 2+ )concentration.

[0036] Example 1

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

[0038] (1) Solution preparation: Prepare a series of stannous chloride standard solutions with a concentration gradient ranging from 0 μM to 128 μM; prepare 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 0.2 mM TMB solution;

[0039] (2) Drawing of the standard curve: Add 10 μL of a certain concentration of stannous chloride standard solution into a cuvette, then add 25 μL of Ce-UiO-66-NO2 reserve solution, 925 μL of ABS buffer solution and 40 μL of TMB solution, shake evenly to obtain a mixed reagent, monitor the mixed reagent with an ultraviolet spectrophotometer to obtain the absorbance value at 652 nm, and record the absorbance value measured when the concentration of the stannous chloride standard solution is 0 as A o , the tin ions (Sn 2+ ) When the concentration of the standard solution is other values, the absorbance value measured is recorded as A n , according to the formula ΔA=A o -A n Calculate the absorbance change ΔA to obtain the absorbance change ΔA of different concentrations of stannous chloride standard solution in the mixed reagent; use different concentrations of stannous chloride standard solution to draw a graph to obtain the absorbance change ΔA with tin ions (Sn 2+ ) a linear standard curve that varies with the concentration of the standard solution;

[0040] (3) Sample testing: Use the sample to be tested to replace the tin ion (Sn 2+ ) standard solution, the same Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution as in step (2) were mixed evenly to obtain a mixed reagent, and the absorbance value A was obtained by testing. n Calculate the absorbance change ΔA and obtain the tin ion (Sn 2+ )concentration.

[0041] Example 2

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

[0043] (1) Solution preparation: Prepare a series of stannous chloride standard solutions with a concentration gradient ranging from 0 μM to 128 μM; prepare 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 0.5 mM TMB solution;

[0044] (2) Drawing of the standard curve: Add 10 μL of a certain concentration of stannous chloride standard solution into a cuvette, then add 25 μL of Ce-UiO-66-NO2 reserve solution, 925 μL of ABS buffer solution and 40 μL of TMB solution, shake evenly to obtain a mixed reagent, and monitor the mixed reagent with an ultraviolet spectrophotometer to obtain the absorbance value at 652 nm. The absorbance value measured when the concentration of the stannous chloride standard solution is 0 is recorded as A o , the absorbance value measured when the concentration of the stannous chloride standard solution is other values ​​is recorded as A n , according to the formula ΔA=A o -A n Calculate the absorbance change ΔA to obtain the absorbance change ΔA of different concentrations of stannous chloride standard solution in the mixed reagent; use different concentrations of stannous chloride standard solution to draw a graph to obtain the absorbance change ΔA with tin ions (Sn 2+ ) a linear standard curve that varies with the concentration of the standard solution;

[0045] (3) Sample testing: Substitute the sample to be tested for the stannous chloride standard solution, shake the same Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution as in step (2) to obtain a mixed reagent, and test to obtain the absorbance value A n Calculate the absorbance change ΔA and obtain the tin ion (Sn 2+ )concentration.

[0046] Example 3

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

[0048] (1) Solution preparation: Prepare a series of stannous chloride standard solutions with a concentration gradient ranging from 0 μM to 128 μM; prepare 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: Add 10 μL of a certain concentration of stannous chloride standard solution into a cuvette, then add 25 μL of Ce-UiO-66-NO2 reserve solution, 925 μL of ABS buffer solution and 40 μL of TMB solution, shake evenly to obtain a mixed reagent, and monitor the mixed reagent with an ultraviolet spectrophotometer to obtain the absorbance value at 652 nm. The absorbance value measured when the concentration of the stannous chloride standard solution is 0 is recorded as A o , the absorbance value measured when the concentration of the stannous chloride standard solution is other values ​​is recorded as A n , according to the formula ΔA=Ao -A n Calculate the absorbance change ΔA to obtain the absorbance change ΔA of different concentrations of stannous chloride standard solution in the mixed reagent; use different concentrations of stannous chloride standard solution to draw a graph to obtain the absorbance change ΔA with tin ions (Sn 2+ ) a linear standard curve that varies with the concentration of the standard solution;

[0050] (3) Sample testing: Use the sample to be tested to replace the tin ion (Sn 2+ ) standard solution, the same Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution as in step (2) were shaken evenly to obtain a mixed reagent, and the absorbance value A was obtained by testing. n Calculate the absorbance change ΔA and obtain the tin ion (Sn 2+ )concentration.

[0051] Under the optimal test conditions of Example 3, the test results are as follows Figure 5 , showing the UV spectra of the reaction system at different tin ion concentrations and the corresponding color change trend of oxTMB. As the concentration of tin ions increases from 0μM-128μM, the absorbance at 652nm decreases continuously, and the solution can be observed to change from dark blue to colorless with the naked eye. The above phenomenon proves that the addition of tin ions can inhibit the activity of Ce-UiO-66-NO2 type oxide mimic enzymes, and the qualitative and quantitative detection of tin ions can be achieved through the change of absorbance at 652nm. Figure 6 , through the absorbance change of the reaction system solution under different tin ion concentrations, the corresponding linear equation can be obtained as ΔA 652 =-0.0063X+0.8619, R 2 =0.9938, with a linear range from 0μM to 128μM and a detection limit (LOD) of 0.33μM. This sensor has a low detection limit and good analytical performance, which will be beneficial for its application in environmental monitoring.

[0052] Selectivity analysis

[0053] Selectivity is an influencing factor that must be considered when designing an excellent analytical sensing system. Potential interfering substances in tap water are mostly metal ions. In this experiment, potential metal ion interfering substances in tap water were tested. The selectivity of the system for tin ions was evaluated. 10 μL of the test sample was added to multiple identical colorimetric sensing systems (925 μL of 0.1 M ABS buffer solution with a pH value of 3.5, 40 μL of 0.4 mM TMB buffer solution, and 25 μL of 1 mg / mL Ce-UiO-66-NO2 reserve solution). Various common interfering substances were added to the test samples. The tin ion concentration was 104 μM, and the interfering ion concentration was ten times that of the tin ion concentration (1040 μM). The test results are shown in Figure 2. Figure 7 It can be seen that only the addition of tin ions can reduce the catalytic activity of the oxidase-like enzyme in the system, while whether it is chromium ions, mercury ions, cobalt ions, sulfur ions, sulfate ions, carbonate ions, manganese ions, nickel ions, lead ions, or copper ions, even if the concentration of these interferents is higher than that of tin ions, the change in the absorbance of the reaction system is negligible, indicating that these metal ions cannot reduce the oxidation ability of Ce-UiO-66-NO2 nanozyme on TMB, thereby causing the reaction system to be inactive at A. 652 There is still a high absorbance at the bottom, which shows that the system has a high selectivity for the detection of tin ions.

[0054] Reproducibility analysis

[0055] Prepare 5 groups of 925 μL of 0.1M, pH 3.5 ABS buffer solution, 40 μL of 0.4mM TMB buffer solution, 25 μL of 1mg / mL Ce-UiO-66-NO2 stock solution and 10 μL of 104μM tin ion solution, and test their absorbance to conduct reproducibility experiments. 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 tin ions in real samples, tap water was spiked with three different concentrations of tin ions using the standard addition method. The analytical results are listed in the table below. Tin ion recoveries ranged from 97.5% to 101%, with relative standard deviations (RSDs) ranging from 2.4% to 4.0% (n=3). This indicates that the Ce-UiO-66-NO2 nanozyme-based colorimetric method is suitable for detecting tin ions in real samples.

[0060] Table 1 Detection of actual tap water 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 tin ions based on Ce-UiO-66-NO2 nanozyme, characterized in that: The method is to mix the Ce-UiO-66-NO2 nanozyme reserve solution with colorless 3,3',5,5'-tetramethylbenzidine (TMB) buffer to generate blue oxidized TMB, and then add tin ions (Sn 2+ ) samples, using tin ions (Sn 2+ )'s strong reducing property reduces the oxidized TMB, thus making the solution color lighter; According to the color change of tin ions (Sn 2+ ) for qualitative detection, or by adding tin ions (Sn 2+ ) and the changes in the absorbance of the solution before and after tin ions (Sn 2+ ) concentration to achieve a linear relationship between the tin ion (Sn 2 + ) quantitative detection.

2. The method for detecting tin ions according to claim 1, wherein The specific steps of the quantitative detection are: (1) Solution preparation: Prepare a series of tin ion (Sn 2+ ) standard solution; and prepare Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution; (2) Drawing of standard curve: Draw a certain concentration of tin ions (Sn 2+ ) standard solution was added to the cuvette, 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 an ultraviolet spectrophotometer to obtain the absorbance value at 652nm, and the tin ion (Sn 2+ ) The absorbance value measured when the concentration of the standard solution is 0 is recorded as A o , the tin ions (Sn 2+ ) When the concentration of the standard solution is other values, the absorbance value measured is recorded as A n , according to the formula ΔA=A o -A n Calculate the absorbance change ΔA to obtain the different concentrations of tin ions (Sn 2+ ) standard solution in the mixed reagent absorbance value change value ΔA; using different concentrations of tin ions (Sn 2+ ) standard solution and obtain the absorbance change ΔA with the change of tin ions (Sn 2+ ) a linear standard curve that varies with the concentration of the standard solution; (3) Sample testing: Use the sample to be tested to replace the tin ion (Sn 2+ ) standard solution, the same Ce-UiO-66-NO2 reserve solution, ABS buffer solution and TMB solution as in step (2) were shaken evenly to obtain a mixed reagent, and the absorbance value A was obtained by testing. n , calculate the absorbance change ΔA=A o -A n According to the linear standard curve, the tin ion (Sn 2+ )concentration.

3. The method for detecting tin 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.

4. The method for detecting tin ions according to claim 2, wherein: The concentration of the Ce-UiO-66-NO2 reserve solution in steps (2) and (3) is 1 mg / mL, and the amount added is 25 μL; the concentration of the ABS buffer solution is 0.1 M, the pH value is 3.0-4.0, and the amount added is 925 μL; the concentration of the TMB buffer solution is 0.2-0.5 mM, and the amount added is 40 μL; the amount added of the tin ion standard solution in step (2) and the sample to be tested in step (3) is 10 μL.

5. The method for detecting tin 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 tin 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.

Images