Preparation method of copper-6-mercapto purine metal organic gel and application thereof in detection of perfluorooctyl sulfonic acid

Abstract

The application discloses a preparation method of copper-6-mercaptopurine metal organic gel and application thereof in perfluorooctyl sulfonic acid detection, and belongs to the technical field of optical sensing, wherein the preparation method takes 6-mercaptopurine as a reducing agent and a complexing agent, and prepares copper-6-mercaptopurine metal organic gel through a hydrothermal method. The copper-6-mercaptopurine metal organic gel prepared by the application has very high peroxidase-like activity, can efficiently catalyze a substrate 3,3',5,5'-tetramethylbenzidine (TMB) to generate an oxidation product TMB (oxTMB) in the presence of H2O2, and thus can be used as a novel peroxide mimicking nano-enzyme. The application also discloses a colorimetric sensor based on the above copper-6-mercaptopurine metal organic gel and used for perfluorooctyl sulfonic acid detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical sensing, and particularly relates to a preparation method of a copper-6-mercapto purine metal organic gel and application thereof in perfluorooctyl sulfonic acid detection. BACKGROUND

[0002] Perfluorooctyl sulfonic acid (PFOS) is a man-made aliphatic compound. Because PFOS has excellent chemical properties such as good thermal stability, it is widely used in surface coating, surfactant, flame retardant material and food packaging fields. However, because the fluorine atoms in PFOS replace all hydrogen atoms on the alkyl group, PFOS has high toxicity. In addition, PFOS also has properties such as non-degradability and bioaccumulation, so PFOS is a new type of persistent pollutant. PFOS causes certain harm to human liver energy, endocrine, immune cells and other functions, thereby endangering human health. PFOS exists in surface water, soil, plants and organisms, so PFOS also poses a great threat to the environment. In view of the serious harm of PFOS to public health and the environment, it is very meaningful to find a simple, rapid and sensitive PFOS detection method. At present, the detection methods of PFOS include gas chromatography-mass spectrometry, high performance liquid chromatography-mass spectrometry, photoelectrochemical analysis method and the like. However, these methods need professional personnel to operate, the sample preparation is complex, time-consuming and high in cost, and therefore it is very necessary to develop an economical, simple and rapid PFOS detection method.

[0003] Metal gels have the advantages of large specific surface area, tunable structure, rich metal sites and good stability, and are widely used in the fields of sensing, adsorption, catalysis, sewage treatment and dye adsorption. Copper has the advantages of wide raw material source, low cost, easy preparation and good catalytic performance, and therefore copper metal organic gels are particularly concerned by researchers in the fields of catalysis and environmental detection. However, there is no report on copper metal organic gels coordinated by 6-mercapto purine and used for sensitive detection of PFOS. SUMMARY

[0004] In view of the deficiencies and problems in the prior art, the preparation method of the copper-6-mercapto purine metal organic gel and the application thereof in PFOS detection has the advantages of high sensitivity, rapidness and good selectivity.

[0005] The application is implemented by the following technical solutions:

[0006] The application provides a preparation method of copper-6-mercapto purine metal organic gel.

[0007] S1, 20-600 volume parts of 100mM copper nitrate, 3-89 volume parts of 170mM 6-mercapto purine DMF solution and appropriate amount of ultrapure water are sequentially added in a container and mixed uniformly, and the final volume is 1000 volume parts;

[0008] S2, the mixture solution of step S1 is heated in a 35-95℃ water bath for 1-7h, and after cooling to room temperature, centrifugation is performed at 12000rpm / min for 10min, and ultrapure water is washed for three times, and the copper-6-mercapto purine metal organic gel obtained from the lower layer.

[0009] Preferably, the amount of copper nitrate in step S1 is 80 volume parts, the amount of 6-mercapto purine is 65 volume parts, the reaction temperature in step S2 is 65℃, and the reaction time is 3h.

[0010] The application also provides the copper-6-mercapto purine metal organic gel prepared by the above method.

[0011] The application also provides the application of the above copper-6-mercapto purine metal organic gel, and the copper-6-mercapto purine metal organic gel is used for perfluorooctyl sulfonic acid detection.

[0012] The specific application method is as follows:

[0013] (1) a plurality of detection solutions are prepared, 50 volume parts of copper-6-mercapto purine metal organic gel, 200 volume parts of acetic acid-sodium acetate buffer solution, different concentrations of perfluorooctyl sulfonic acid solution, 50 volume parts of TMB, 100 volume parts of H2O2 are added, and water is added to dilute to a total volume of 2000 volume parts, to obtain a plurality of detection solutions;

[0014] (2) each group of detection solutions is mixed uniformly, and reaction is performed at room temperature for 5min;

[0015] (3) the mixed solution prepared in step (2) is measured for ultraviolet-visible absorption spectrum;

[0016] (4) perfluorooctyl sulfonic acid is detected according to the relationship between the absorption peak intensity of the TMB oxidation product (oxTMB) at 652nm corresponding to different concentrations of perfluorooctyl sulfonic acid.

[0017] With the increase of the concentration of perfluorooctyl sulfonic acid, the ability of copper-6-mercaptopurine metal organic gel to catalyze the oxidation of TMB in the presence of H2O2 is obviously decreased, the absorption peak intensity of oxTMB at 652nm is gradually weakened, the concentration of perfluorooctyl sulfonic acid and the absorbance of oxTMB are linear in the range of 0.025-2uM, and the detection limit is 5.3nM.

[0018] As preferred, the concentration of the acetic acid-sodium acetate diluted buffer solution is 100mM, and the pH is 4.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The present application uses copper nitrate as a source material, 6-mercaptopurine as a reducing agent and a complexing agent, and one-step prepares copper-6-mercaptopurine metal organic gel by a hydrothermal method, and the copper-6-mercaptopurine metal organic gel has high peroxidase-like activity and good stability.

[0021] (2) The copper-6-mercaptopurine metal organic gel prepared by the present application is used to construct a colorimetric sensor for sensitive detection of perfluorooctyl sulfonic acid, and has the advantages of high sensitivity, rapidness and good selectivity. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a photo of the copper-6-mercaptopurine metal organic gel of the present application;

[0023] Figure 2 is a performance research map of the enzyme activity of the copper-6-mercaptopurine metal organic gel of the present application;

[0024] Figure 3 is an ultraviolet-visible absorption spectrum of the copper-6-mercaptopurine metal organic gel for detecting perfluorooctyl sulfonic acid;

[0025] Figure 4 is a selectivity diagram of the copper-6-mercaptopurine metal organic gel of the present application. DETAILED DESCRIPTION

[0026] The present application will be further described below in conjunction with the drawings.

[0027] Example 1 Preparation of copper-6-mercaptopurine metal organic gel

[0028] The method uses copper nitrate as a raw material and 6-mercaptopurine as a reducing agent and a complexing agent to one-step prepare copper-6-mercaptopurine metal organic gel by a hydrothermal method. The method specifically includes the following steps:

[0029] S1, add 20-600 volume parts of 100 mM copper nitrate, 3-89 volume parts of 170 mM 6-mercapto purine DMF solution, and an appropriate amount of ultrapure water into the container in sequence, mix uniformly, and the final volume is 1000 volume parts;

[0030] S2, heat the mixture solution of step S1 in a 35-95 °C water bath for 1-7 h. After cooling to room temperature, centrifuge at 12000 rpm / min for 10 min, wash with ultrapure water three times, and take the lower layer to obtain the copper-6-mercapto purine metal organic gel.

[0031] (1) Optimization of the amount of copper nitrate, 6-mercapto purine, N, N-dimethylformamide, reaction temperature and time.

[0032] The results show that, with the increase of the amount of copper nitrate, the ultraviolet absorbance gradually increases and then gradually balances, and the best amount is 80 μL; with the increase of the amount of 6-mercapto purine, the ultraviolet absorbance gradually weakens and the gelation ability gradually increases and then weakens, and the best amount is 65 μL; with the increase of the reaction temperature, the ultraviolet absorbance gradually weakens, then gradually increases, and then gradually weakens, and the best reaction temperature is 65 °C; with the increase of the reaction time, the ultraviolet absorbance gradually increases and then weakens, and the best reaction time is 3 h.

[0033] (2) Preparation of copper-6-mercapto purine metal organic gel under the best conditions: mix 80 μL of 100 mM copper nitrate, 65 μL of 170 mM 6-mercapto purine DMF solution, and finally add an appropriate amount of ultrapure water to make the total volume 1 mL, mix uniformly, react at 65 °C for 3 h, centrifuge at 12000 rpm / min for 10 min, wash with ultrapure water three times, and the lower layer is the copper-6-mercapto purine metal organic gel.

[0034] Figure 1 The photo of copper-6-mercapto purine metal organic gel can be clearly seen, and the brown gel is firmly attached to the bottom of the bottle. From Figure 2 It can be seen that only copper-6-mercapto purine metal organic gel and H2O2 can catalyze the oxidation of TMB, which indicates that the copper hydrogel has strong catalytic properties of peroxidase.

[0035] Example 2 Detection application of copper-6-mercapto purine metal organic gel for perfluorooctylsulfonic acid

[0036] (1) 50 μL of copper-6-mercapto purine metal-organic gel, 200 μL of acetic acid-sodium acetate buffer solution (concentration of 100 mM, pH 4), different concentrations of perfluorooctyl sulfonic acid solution, 50 μL of TMB, 100 μL of H2O2, and water were added to dilute to a total volume of 2 mL to obtain a plurality of detection solutions; uniformly mixed, reacted at room temperature for 5 min, and the ultraviolet-visible absorption spectrum was measured. As shown in Figure 3 , with the increase of the concentration of perfluorooctyl sulfonic acid, the absorption peak intensity of oxTMB at 652 nm gradually weakened, and the concentration of perfluorooctyl sulfonic acid and the absorbance of oxTMB were linearly related in the range of 0.025-2 μM, the detection limit was 5.3 nM, which could be used for high-sensitivity detection of perfluorooctyl sulfonic acid.

[0037] (2) The selectivity of copper-6-mercapto purine metal-organic gel to perfluorooctyl sulfonic acid detection is shown in Figure 4 , except for perfluorooctyl sulfonic acid, other cations and anions including Zn 2+ , Cd 2+ , Cu 2+ , Fe 2+ , Fe 3+ , Ba 2+ , Cr 3+ , Mn 2+ , Na + , Pb 2+ , Al 3+ , K + , Co 2+ , Cl - , SO4 2- , PO4 3- , NO3 - , HPO4 2- , H2PO4 - , and humic acid and bovine serum albumin, etc. have no obvious response, indicating that the gel nanozyme has good selectivity for perfluorooctyl sulfonic acid detection.

[0038] The above only expresses the preferred embodiments of the present application, which are described in more detail and in more detail, but cannot be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications, improvements and substitutions can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a copper-6-mercaptopurine metal organic gel, characterized in that: The method uses copper nitrate as a raw material and 6-mercaptopurine as a reducing agent and a coordination agent to prepare copper-6-mercaptopurine metal organic gel in one step through a hydrothermal method. The method comprises the following steps: S1. Add 20-600 parts by volume of copper nitrate, 3-89 parts by volume of 6-mercaptopurine in DMF solution, and appropriate amount of ultrapure water into a container and mix them evenly to a final volume of 1000 parts by volume; S2. The mixture solution is heated in a water bath at 35-95°C for 1-7 hours; after cooling to room temperature, the mixture solution is subjected to high-speed centrifugation and washed with ultrapure water, and the lower layer is removed to obtain the copper-6-mercaptopurine metal organic gel.

2. The method for preparing the copper-6-mercaptopurine metal organic gel according to claim 1, wherein: In step S1, the amount of copper nitrate used is 80 parts by volume, and the concentration thereof is 100 mM; the amount of 6-mercaptopurine used is 65 parts by volume, and the concentration thereof is 170 mM.

3. The method for preparing the copper-6-mercaptopurine metal organic gel according to claim 1, wherein: The reaction temperature in step S2 is 65° C. and the reaction time is 3 h.

4. The copper-6-mercaptopurine metal organic gel prepared by the method according to any one of claims 1 to 3.

5. Use of the copper-6-mercaptopurine metal organic gel prepared by the method according to any one of claims 1 to 3, characterized in that: A colorimetric sensor is constructed based on the copper-6-mercaptopurine metal organic gel for detecting perfluorooctane sulfonic acid.

6. The use according to claim 5, characterized in that The application method comprises: (1) Preparing multiple sets of detection solutions: 50 parts by volume of copper-6-mercaptopurine metal organic gel, 200 parts by volume of acetic acid-sodium acetate buffer solution, different concentrations of perfluorooctane sulfonic acid solution, 50 parts by volume of TMB, and 100 parts by volume of H2O2 were added, and diluted with water to a total volume of 2000 parts by volume to obtain multiple sets of detection solutions; (2) Mix the test solutions of each group evenly and react at room temperature for 5 minutes; (3) measuring the UV-visible absorption spectrum of the mixed solution prepared in step (2); (4) PFOS was detected based on the relationship between the absorption peak intensities of TMB oxidation products (oxTMB) at 652 nm corresponding to different concentrations of PFOS.

7. The use according to claim 6, characterized in that: The concentration of the acetic acid-sodium acetate buffer solution in step (1) is 100 mM and the pH is 4.

8. The use according to claim 6, characterized in that: With the increase of PFOS concentration, the absorption peak intensity of oxTMB at 652 nm gradually weakened. The PFOS concentration and the absorbance of oxTMB showed a linear relationship in the range of 0.025~2 μM, with a detection limit of 5.3 nM.

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