Humic acid interference resistant polymer membrane ion selective electrode and preparation and application thereof

Abstract

The invention belongs to the field of potentiometric anti-fouling sensors, and particularly relates to a humic acid interference resistant polymer membrane ion selective electrode as well as preparation and application thereof. The selective electrode is formed by sequentially adhering a polymer sensitive film and a protective layer to the bottom of an electrode substrate; wherein the protective layer is a polyvinylidene fluoride coating. By virtue of the characteristics of low surface energy, strong electronegativity and compact film formation of the polyvinylidene fluoride coating, the infiltration and adhesion of humic acid on the surface of the electrode film are reduced, and the humic acid is effectively prevented from entering the polymer film, so that the stability and the service life of the polymer film ion-selective electrode in complex environmental water application are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of potential type anti-fouling sensor, and particularly relates to a humic acid interference resistant polymer membrane ion selective electrode and preparation and application thereof. BACKGROUND

[0002] As a common electrochemical sensor, the polymer membrane ion selective electrode has been widely applied in environmental analysis due to its simple operation, fast detection speed, continuous detection and no influence of sample color and turbidity. Among them, humic acid as a common dissolved organic matter widely exists in environmental water such as river water and seawater, and soil and sediment. The environmental humic acid causes great challenge to the application of the polymer membrane ion selective electrode in complex environmental samples.

[0003] At present, the sensitive film of the polymer membrane ion selective electrode is generally composed of a polymer matrix material, a plasticizer, an ion carrier and an ion exchanger. The polymer matrix is mainly a hydrophobic material such as polyvinyl chloride, and the plasticizer is also easily dissolved in an organic reagent, which makes the surface of the electrode sensitive film lipophilic. This causes the dissolved humic acid in the detection solution to adhere to the surface of the electrode sensitive film through hydrophobic interaction, and enter the inside of the sensitive film through extraction, thereby changing the composition of the sensitive film. The above reasons will affect the thermodynamic response of the electrode, resulting in unstable electrode response, decreased detection performance and greatly shortened service life. At present, the humic acid in the sample is usually removed by pretreatment to reduce its influence on the polymer membrane ion selective electrode, and the research on how to improve the humic acid resistance of the electrode during in-situ detection in complex environments has not been reported. SUMMARY

[0004] The application aims to provide a humic acid interference resistant polymer membrane ion selective electrode and preparation and application thereof.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0006] A humic acid interference resistant polymer membrane ion selective electrode, the selective electrode is sequentially adhered with a polymer sensitive film and a protective layer on the bottom of an electrode substrate; wherein the protective layer is a polyvinylidene fluoride coating.

[0007] A conductive layer can be further arranged between the substrate and the polymer sensitive film.

[0008] The conventional electrode substrate can be a glassy carbon electrode, a gold electrode or a platinum electrode, etc.

[0009] The polyvinylidene fluoride coating is formed by dissolving polyvinylidene fluoride in N,N-dimethylformamide solution and coating on the surface of the electrode base polymer membrane; wherein the concentration of polyvinylidene fluoride in the solution is 2%-10% by mass percentage; the N,N-dimethylformamide solution is a mixture of N,N-dimethylformamide and tetrahydrofuran with a volume ratio of 1:0-1:1.

[0010] A preparation method of the anti-humic acid interference polymer membrane ion selective electrode, wherein a solution containing polyvinylidene fluoride is drop-coated on the surface of the sensitive membrane of the polymer membrane ion selective electrode to form a polyvinylidene fluoride coating.

[0011] The polymer membrane ion selective electrode is a solid contact polymer sensitive membrane cation / anion selective electrode or a liquid contact polymer sensitive membrane cation / anion selective electrode containing a polymer sensitive membrane.

[0012] The solution containing polyvinylidene fluoride is dried on the surface of the sensitive membrane of the polymer membrane ion selective electrode for 10-15 minutes, and then the electrode is immersed in deionized water to keep the polyvinylidene fluoride coating moist, thereby obtaining the anti-humic acid interference polymer membrane ion selective electrode.

[0013] The polyvinylidene fluoride coating is formed by dissolving polyvinylidene fluoride in N,N-dimethylformamide solution and coating on the surface of the electrode base polymer membrane; wherein the concentration of polyvinylidene fluoride in the solution is 2%-10% by mass percentage; the N,N-dimethylformamide solution is a mixture of N,N-dimethylformamide and tetrahydrofuran with a volume ratio of 1:0-1:1.

[0014] The polymer sensitive membrane is composed of an ion selective carrier, a lipophilic ion exchanger, a membrane base material, and a plasticizer in a weight ratio of 0.2-10:0.1-5:20-40:40-80.

[0015] The membrane base material includes but is not limited to polyvinyl chloride, polyurethane, silicone rubber, acetate fiber, polyacrylamide, or polymethyl methacrylate-dimethylaminoethyl methacrylate; the plasticizer includes but is not limited to o-nitrophenyl octyl ether, dioctyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl adipate, or dioctyl sebacate; the ion selective carrier includes but is not limited to lead ion, copper ion, iron ion, chromium ion, sodium ion, potassium ion, ammonium ion, calcium ion, magnesium ion, carbonate ion, nitrate ion, chloride ion, or bromide ion; and the lipophilic ion exchanger includes but is not limited to sodium tetrakis(3,5-di(trifluoromethyl)phenyl)borate or tridodecylammonium chloride.

[0016] The anti-humic acid interference polymer membrane ion selective electrode is applied in the detection of environmental water bodies against humic acid interference.

[0017] The anti-humic acid interference polymer membrane ion selective electrode can be applied to analysis of environmental water bodies including lake water, river water or sea water, and reduces the influence of humic acid in the water body on the detection signal and service life of the electrode.

[0018] Principle: The polyvinylidene coating is modified on the surface of the polymer membrane ion selective electrode film, and the electrode is endowed with the anti-humic acid interference ability by virtue of the low surface energy, strong electronegativity, dense film forming and other characteristics of the polyvinylidene. Further, the low surface energy of the polyvinylidene reduces the infiltration and adhesion of the soluble humic acid molecules with hydrophobic skeleton and amphiphilic surface groups on the electrode surface. At the same time, the polyvinylidene has strong electronegativity due to the C-F bond, and charge repulsion is generated with the electronegative groups such as phenolic hydroxyl and carboxyl on the surface of humic acid, further reducing the adhesion of humic acid. On the other hand, as a semi-crystalline polymer, the polyvinylidene can form a continuous and dense protective layer on the surface of the polymer membrane, thereby effectively preventing humic acid from entering the inside of the polymer membrane. In addition, the polyvinylidene itself does not contain ion exchange sites, and will not affect the normal response of the electrode. Therefore, the polyvinylidene coating can effectively improve the protection ability of the electrode against humic acid in the detection of environmental samples.

[0019] The present application has the advantages that:

[0020] 1. The present application uses polyvinylidene coating to modify the polymer membrane ion selective electrode, thereby improving the anti-humic acid interference ability of the polymer membrane ion selective electrode in the detection of environmental samples.

[0021] 2. The anti-humic acid interference polymer membrane ion selective electrode based on the polyvinylidene coating adopts a drop coating method to construct a protective coating on the surface of the electrode film, and the process is simple and does not affect the detection performance of the electrode.

[0022] 3. The polyvinylidene coating in the anti-humic acid interference ion selective electrode based on the polyvinylidene coating has universality for polymer membrane potential type sensors, and can be used to improve the anti-humic acid interference ability of polymer membrane ion selective electrodes containing different membrane matrix materials and different ion carrier types.

[0023] 4. The present application proposes a polymer membrane potential type anti-fouling sensor which can be applied to various environmental water bodies or samples containing humic acid. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The anti-humic acid interference polymer membrane ion selective electrode based on the polyvinylidene coating provided by the present application is shown in the structure diagram.

[0025] Figure 2 The anti-humic acid interference polymer membrane ion selective electrode based on the polyvinylidene coating provided by the present application is shown in the structure diagram. Figure 1Partial magnified electron microscope picture of the middle protective layer (polyvinylidene fluoride coating).

[0026] Figure 3 Comparison chart of the response of the unmodified and polyvinylidene fluoride modified polymer film chloride ion selective electrode to different concentrations of chloride ions provided by the embodiment of the present application; wherein A is the electrode potential response in a concentration range of 1.0*10 -7 ~1.0*10 -1 M sodium chloride solution, B is the electrode potential-chloride ion activity logarithmic value correction curve.

[0027] Figure 4 Potential drift and physical picture of the unmodified and polyvinylidene fluoride modified polymer film chloride ion selective electrode in humic acid solution provided by the embodiment of the present application; wherein A is the electrode potential drift in humic acid solution, B is the electrode surface physical picture before and after contacting humic acid and after removing the modified layer.

[0028] Figure 5 Comparison chart of the response of the unmodified and polyvinylidene fluoride modified polymer film chloride ion selective electrode to different concentrations of chloride ions provided by the embodiment of the present application; wherein A is the electrode potential response in a concentration range of 1.0*10 -7 ~1.0*10 -1 M sodium chloride solution, B is the electrode potential-chloride ion activity logarithmic value correction curve.

[0029] Figure 6 Potential response chart of the polymer film chloride ion selective electrode based on perfluorosulfonic acid resin coating in a concentration range of 1.0*10 -7 ~1.0*10 -1 M sodium chloride solution provided by the comparative example 1 of the present application.

[0030] Figure 7 Potential drift chart of the polymer film chloride ion selective electrode prepared by the modification method provided by the comparative example 2 and the comparative example 3 in humic acid solution; wherein PVDF is the electrode modified by the polyvinylidene fluoride coating provided by the embodiment of the present application, PDA is the electrode modified by the polydopamine coating provided by the comparative example 2, PVC-DMF is the electrode modified by the polyvinyl chloride-N,N dimethylformamide coating provided by step a of the comparative example 3, and PVC-DOS is the electrode modified by the polyvinyl chloride-decanedioic acid dioctyl ester coating provided by step b of the comparative example 3. DETAILED DESCRIPTION

[0031] The specific embodiments of the present application are further described below in conjunction with examples, which are only for the purpose of illustrating and explaining the present application, and are not limited to the present application.

[0032] Example 1

[0033] Preparation of polymeric membrane chloride ion selective electrode based on polyvinylidene fluoride coating:

[0034] a. Preparation of chloride ion selective sensitive membrane solution: 360 mg of membrane components, including 2.0 wt% chloride ion carrier III, 33.0 wt% polyvinyl chloride particles, 63.8 wt% dioctyl sebacate and 1.2 wt% tridodecylammonium chloride, were weighed and added to 3.6 mL of tetrahydrofuran solution. After complete dissolution, a chloride ion selective electrode sensitive membrane solution was obtained.

[0035] b. Preparation of polymeric membrane chloride ion selective electrode based on polyvinylidene fluoride coating: 100 μL of electrode sensitive membrane solution was uniformly coated on the surface of a glassy carbon electrode containing a conductive layer (in this embodiment, a nickel-cobalt sulfide compound was used as the conductive layer), and was allowed to volatilize at room temperature for 12 h to obtain a polymeric membrane chloride ion selective electrode. 100 mg of polyvinylidene fluoride particles were dissolved in 2 mL of a solution of N,N-dimethylformamide and tetrahydrofuran in a volume ratio of 1:1, and after uniform dissolution, a polyvinylidene fluoride solution was obtained. 10 μL of the polyvinylidene fluoride solution was drop-coated to cover the surface of the electrode sensitive membrane, and was allowed to dry at room temperature for 15 min to form a polyvinylidene fluoride coating. Then, the electrode was immersed in 10 mL of M sodium chloride solution to keep the polyvinylidene fluoride coating moist, and a polymeric membrane chloride ion selective electrode modified with a polyvinylidene fluoride coating was prepared, which had a structure as shown in -3 Figure 1 and Figure 2 .

[0036] Example 2

[0037] Taking the detection of chloride ions as an example, the polymeric membrane chloride ion selective electrode modified with a polyvinylidene fluoride coating obtained in Example 1 (at the same time, a polymeric membrane chloride ion selective electrode without modification of a polyvinylidene fluoride coating prepared according to Example 1 was used as a control) was used as a working electrode, and an Ag / AgCl electrode was used as a reference electrode, and the potential of chloride ions in a 1.0 × 10 -7 ~1.0 × 10 -1 M sodium chloride solution was detected (see Figure 3 ).

[0038] The test results are shown in Figure 3 . After correction, the electrode before and after modification had a potential range of 9.9 × 10 -5 ~7.5 × 10 -2 ​The response of the M chloride ion exhibits a linear response within the activity range. The response slope of the unmodified electrode is -58.6 mV / decade, while that of the modified electrode is -60.0 mV / decade. This is close to the theoretical slope calculated based on the Nernst equation. Furthermore, the response of the electrode remains essentially unchanged before and after the modification with the polyvinylidene fluoride coating, demonstrating that the modification with the polyvinylidene fluoride coating does not affect the response performance of the electrode.

[0039] Example 3

[0040] Antifouling performance tests were conducted using the unmodified polyvinylidene fluoride (PVDF) coated polymer film chloride ion selective electrode and the PVDF-coated polymer film chloride ion selective electrode obtained in Example 1, respectively. Specifically:

[0041] The electrodes obtained in Example 1 were inserted into a solution containing 10 mg / L humic acid. -3 The electrode was immersed in sodium chloride (M) for 1 hour, and the potential change of the electrode was recorded using the method in Example 2. The results are as follows: Figure 4 As shown.

[0042] Depend on Figure 4 It is evident that after contact with humic acid, the potential of the unmodified electrode drops sharply, and the color of the polymer film darkens significantly, indicating that humic acid has entered the membrane through extraction. In contrast, the potential of the electrode modified with polyvinylidene fluoride (PVDF) coating remains stable. Although the color of the PVDF coating darkens, the polymer film remains colorless and transparent after the coating is removed. This demonstrates that the PVDF coating effectively blocks the contact between humic acid and the polymer film substrate, reduces potential drift when the electrode contacts humic acid, and ensures the stability of the potential response.

[0043] The electrode was then removed and rinsed with deionized water. The electrode was tested for concentrations in the range of 1.0 × 10⁻⁶. -7 ~1.0×10 -1 Chloride ion response in sodium chloride solution (see [reference]) Figure 5 The result is as follows: Figure 5 As shown, after contact with humic acid, at 9.9 × 10 -5 ~7.5×10 - 2 Within the chloride ion activity range of M, the slope of the calibration curve for the unmodified electrode dropped sharply from -58.6 mV / decade before contact to -50.7 mV / decade, indicating a decrease in electrode sensitivity. In contrast, the electrode modified with polyvinylidene fluoride coating still exhibited a good response to chloride ions, with the response slope shown in the calibration curve remaining at -57.3 mV / decade. This demonstrates that the surface of the electrode sensitive film modified with polyvinylidene fluoride coating effectively improved the electrode performance.

[0044] Example 4

[0045] Preparation of a polymer membrane carbonate ion selective electrode based on polyvinylidene fluoride coating:

[0046] a. Preparation of carbonate ion-selective sensitive membrane solution: Weigh a total of 360 mg of membrane components, including 5.10 wt% carbonate ion carrier VII, 36.98 wt% polyvinyl chloride, 56.78 wt% dioctyl adipate, and 1.23 wt% tri(dodecyl)ammonium chloride, and add them to 3.6 mL of tetrahydrofuran solution. After complete dissolution, the carbonate ion-selective electrode sensitive membrane solution is obtained.

[0047] b. Preparation of a carbonate ion-selective electrode based on a polyvinylidene fluoride (PVDF) coating: 100 μL of a carbonate ion-selective sensitive membrane solution was uniformly coated onto the surface of a glassy carbon electrode containing a conductive layer (in this embodiment, the conductive layer is a nickel-cobalt-sulfur compound), and allowed to evaporate at room temperature for 12 h to obtain a polymer membrane carbonate ion-selective electrode. 100 mg of PVDF particles were dissolved in 2 mL of a solution of N,N-dimethylformamide and tetrahydrofuran in a 1:1 volume ratio, and the solution was homogeneous to obtain a PVDF solution. 10 μL of the PVDF solution was drop-coated onto the surface of the electrode sensitive membrane and dried at room temperature for 15 min to form a PVDF coating. The electrode was then immersed in a solution containing 10... -3 A polyvinylidene fluoride (PVDF) coated polymer membrane carbonate ion selective electrode was prepared by keeping the PVDF coating moist in a buffer solution of 0.1 M sodium carbonate, with a background of pH 8.0, 0.1 M tris(hydroxymethyl)aminomethane hydrochloride, and hydrochloric acid.

[0048] c. Using the electrode obtained in step b, insert it into a buffer solution containing 10 mg / L humic acid with a background pH of 8.0, 0.1 M tris(hydroxymethyl)aminomethane hydrochloride, and hydrochloric acid. -3 After soaking in a sodium carbonate solution for 1 day, the electrode was removed and rinsed with deionized water. The electrode was tested for concentrations ranging from 5 × 10⁻⁶. -2 ~1×10 -6 M carbonate ion response (with the buffer solution as described above as the solution background). After contact with humic acid, the polyvinylidene fluoride coated electrode still maintains a good response to carbonate ions.

[0049] Comparative Example 1

[0050] Preparation and detection of chloride ion selective electrodes based on polymer membranes coated with perfluorosulfonic acid resin:

[0051] a. Preparation of a chloride ion selective electrode based on a perfluorosulfonic acid resin coating: Using the polymer membrane chloride ion selective electrode obtained in Example 1, 0.2 mL of 5 wt% perfluorosulfonic acid resin was dissolved in 0.8 mL of anhydrous ethanol and sonicated for 20 min to prepare a 1 wt% perfluorosulfonic acid resin solution. 20 μL of the perfluorosulfonic acid resin solution was drop-coated onto the surface of the electrode's sensitive membrane and dried at room temperature for 15 min to form a perfluorosulfonic acid resin coating. The electrode was then immersed in 10... -3 A perfluorosulfonic acid resin coating modified with a polymer membrane chloride ion selective electrode was prepared by keeping the perfluorosulfonic acid resin coating moist in a sodium chloride solution.

[0052] b. Using the method in Example 2, the modified electrode obtained in step a was tested at a concentration range of 1.0 × 10⁻⁶. -7 ~1.0×10 -1 Potential response in sodium chloride solution M. Test results are as follows: Figure 6 As shown, the chloride ion electrode modified with perfluorosulfonic acid resin coating could no longer maintain the Nernst response, and even showed a response trend of a cation electrode, indicating that the perfluorosulfonic acid resin seriously affected the normal response of the electrode.

[0053] Perfluorosulfonic acid resin is a commonly used antifouling material in electrochemical sensor research. However, it is a cation exchanger with ion exchange sites, which can introduce a large number of cations from the solution onto the polymer membrane surface, interfering with the electrode's normal response to chloride ions. Therefore, perfluorosulfonic acid resin coatings are not suitable for constructing the humic acid-resistant polymer membrane ion-selective electrode of this invention.

[0054] Comparative Example 2

[0055] Preparation and detection of chloride ion selective electrodes based on polymer membranes with polydopamine coating:

[0056] a. Preparation of chloride ion selective electrode based on polydopamine coating: Using the polymer membrane chloride ion selective electrode obtained in Example 1, the electrode was immersed in a buffer solution of 10 mM tris(hydroxymethyl)aminomethane hydrochloride and hydrochloric acid with a background pH of 8.5 for 12 h to obtain the polydopamine-coated polymer membrane chloride ion selective electrode.

[0057] b. Using the method in Example 2, the modified electrode obtained in step a was tested at a concentration range of 1.0 × 10⁻⁶. -7 ~1.0×10 -1 Potential response in sodium chloride solution. The response slope of the modified electrode is close to the theoretical slope, proving that the polydopamine coating does not affect the electrode's response performance.

[0058] c. Insert the modified electrode obtained in step a into a container containing 10 mg / L humic acid. -3 The electrode was immersed in sodium chloride (M), and the potential change when the electrode came into contact with humic acid was recorded using the method of Example 2. The results are shown in […]. Figure 7 Upon contact with humic acid, compared to the polyvinylidene fluoride coating used in the example, the electrode modified with the polydopamine coating showed a slow decrease in potential, indicating that the coating has a certain blocking effect on humic acid, but cannot completely protect the electrode from the influence of humic acid.

[0059] Polydopamine is widely used as an antifouling modifier due to its hydrophilicity and electronegativity. However, the resulting coating is a cross-linked network structure with a thin thickness of only a few hundred nanometers, making it difficult to completely block the passage of large molecules such as polyions and humic acids. Furthermore, polydopamine possesses phenolic hydroxyl groups, which can interact with anion exchangers such as tris(dodecyl)ammonium chloride in the polymer membrane. Therefore, polydopamine coatings are not suitable for constructing the humic acid-resistant polymer membrane ion-selective electrode of this invention.

[0060] Comparative Example 3

[0061] Preparation and detection of chloride ion selective electrodes based on polymer membranes with polyvinyl chloride coating:

[0062] a. Preparation of a chloride ion selective electrode based on a polyvinyl chloride-N,N-dimethylformamide coating: Using the polymer membrane chloride ion selective electrode obtained in Example 1, and referring to the preparation of the polyvinylidene fluoride coating in Example 1, the polyvinylidene fluoride particles were replaced with polyvinyl chloride powder. 100 mg of polyvinyl chloride powder was dissolved in 2 mL of a solution of N,N-dimethylformamide and tetrahydrofuran in a 1:1 volume ratio. After uniform dissolution, a polyvinyl chloride-N,N-dimethylformamide solution was obtained. 10 μL of this solution was drop-coated onto the surface of the electrode sensitive membrane and dried at room temperature for 15 min to form a coating. The electrode was then immersed in 10... -3 A polyvinyl chloride-N,N-dimethylformamide coating-modified polymer membrane chloride ion selective electrode was prepared by keeping the coating moist in a sodium chloride solution.

[0063] b. Preparation of chloride ion selective electrode based on polyvinyl chloride-dioctyl sebacate coating: Referring to step a, N,N-dimethylformamide was replaced with plasticizer dioctyl sebacate to obtain a polymer film chloride ion selective electrode modified with polyvinyl chloride-dioctyl sebacate coating.

[0064] c. Using the method in Example 2, the modified electrodes obtained in steps a and b were tested at concentrations within the range of 1.0 × 10⁻⁶. -7 ~1.0×10 -1Potential response in sodium chloride solution M. The response slopes of the two modified electrodes are close to the theoretical slopes, proving that the PVC coating does not affect the electrode's response performance.

[0065] d. Insert the modified electrode obtained using steps a and b into a solution containing 10 mg / L humic acid. -3 The electrode was immersed in sodium chloride (M), and the potential change when the electrode came into contact with humic acid was recorded using the method of Example 2. The results are shown in […]. Figure 7 .

[0066] Upon contact with humic acid, the electrode potential modified with a polyvinyl chloride-N,N-dimethylformamide coating decreased slowly, indicating that the coating provides some protection against humic acid, but cannot completely block its influence on the electrode. Polyvinyl chloride (PVC) is a polymer with a structure similar to polyvinylidene fluoride (PVDF) and is also the matrix material for polymer films. Although it possesses certain hydrophobicity and electronegativity, PVC is an amorphous polymer, and dissolving in N,N-dimethylformamide prevents it from forming a dense protective coating, thus failing to effectively protect the electrode from humic acid interference.

[0067] Therefore, in step b, N,N-dimethylformamide was replaced with the plasticizer dioctyl sebacate, and the electrode was modified with a polyvinyl chloride-dioctyl sebacate coating. Upon contact with humic acid, the electrode potential modified with the polyvinyl chloride-dioctyl sebacate coating dropped sharply, indicating that the coating was also ineffective in protecting the electrode from humic acid interference. While the plasticizer helps form a continuous coating of polyvinyl chloride, the composition of this coating is similar to that of the polymer membrane, causing the effective components of the polymer membrane—the ion carriers and ion exchangers—to be extracted into the coating. This results in direct contact between the humic acid and the effective components of the polymer membrane, leading to a significant potential shift. Therefore, the polyvinyl chloride-dioctyl sebacate coating is not suitable for constructing the humic acid-resistant polymer membrane ion-selective electrode of this invention.

Claims

1. A humic acid-resistant polymer membrane ion-selective electrode, characterized in that: The selective electrode consists of a polymer sensitive film and a protective layer sequentially adhered to the bottom of the electrode substrate; the protective layer is a polyvinylidene fluoride coating.

2. The humic acid-resistant polymer membrane ion-selective electrode according to claim 1, characterized in that: A conductive layer is disposed between the substrate and the polymer sensitive membrane.

3. The humic acid-resistant polymer membrane ion-selective electrode according to claim 1, characterized in that: The polyvinylidene fluoride coating is prepared by dissolving polyvinylidene fluoride in an N,N-dimethylformamide solution and coating it onto the surface of the polymer film of the electrode substrate; wherein the concentration of polyvinylidene fluoride in the solution is 2%-10% by mass; the N,N-dimethylformamide solution is prepared by a volume ratio of N,N-dimethylformamide and tetrahydrofuran of 1:0-1:

1.

4. A method for preparing the ion-selective electrode of the humic acid-resistant polymer membrane according to claim 1, characterized in that: A solution containing polyvinylidene fluoride is drop-coated onto the surface of the sensitive membrane of a polymer membrane ion-selective electrode to form a polyvinylidene fluoride coating; wherein, the polymer membrane ion-selective electrode is either a solid contact anion / cation selective electrode containing a polymer sensitive membrane or a liquid contact polymer sensitive membrane anion / cation selective electrode.

5. The method for preparing the ion-selective electrode of the humic acid-resistant polymer membrane according to claim 4, characterized in that: The solution containing polyvinylidene fluoride is dried on the surface of the sensitive membrane of the polymer membrane ion-selective electrode for 10-15 minutes, and then the electrode is immersed in deionized water to keep the polyvinylidene fluoride coating moist, thus obtaining a humic acid-resistant polymer membrane ion-selective electrode.

6. The method for preparing the humic acid-resistant polymer membrane ion-selective electrode according to claim 4 or 5, characterized in that: The polyvinylidene fluoride coating is prepared by dissolving polyvinylidene fluoride in an N,N-dimethylformamide solution and coating it onto the surface of the polymer film of the electrode substrate; wherein the concentration of polyvinylidene fluoride in the solution is 2%-10% by mass; the N,N-dimethylformamide solution is prepared by a volume ratio of N,N-dimethylformamide and tetrahydrofuran of 1:0-1:

1.

7. The application of the humic acid-resistant polymer membrane ion-selective electrode according to claim 1, characterized in that: Application of the polymer membrane ion-selective electrode in the detection of humic acid interference in environmental water.

Images