Copper ferrocyanide / copper benzenehexophenol electrode material as well as preparation method and application of copper ferrocyanide / copper benzenehexophenol electrode material

Abstract

The invention discloses a copper ferrocyanide / copper benzenehexophenol electrode material as well as a preparation method and application thereof, and belongs to the technical field of electroanalytical chemical detection and preparation of composite nano materials. According to the invention, a copper benzenehexophenol conductive metal organic framework is constructed by a sacrificial template method, and rich metal sites of the copper benzenehexophenol conductive metal organic framework are used for in-situ bonding of a Fe-CN ligand to form a copper ferrocyanide / copper benzenehexophenol composite nano material with a built-in oxidation-reduction probe, so that effective amplification of electrochemical signals is realized. On the basis, a high-selectivity molecular imprinting / copper ferrocyanide / copper benzenehexophenol electrode is prepared through an electro-polymerization method. The constructed electrochemical sensor has the advantages of high sensitivity, high specificity, wide detection range and good stability, and can realize the efficient detection of methadone and metabolite 2-ethylidene-1, 5-dimethyl-3, 3-diphenyl pyrrolidine (EDDP) thereof in domestic sewage and river water. The invention provides an effective strategy for constructing a stable and sensitive built-in probe type electrochemical sensor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electroanalytical chemical detection and composite nanomaterial preparation, and particularly relates to an electrochemical sensing composite nanosensing material with built-in redox probe copper ferrocyanide / copper benzene hexathiol and application thereof. BACKGROUND

[0002] Methadone is an artificial synthetic opioid drug, which is widely used for the relief of chronic pain and the replacement therapy of opioid drugs. However, due to its addictive nature, there are problems of abuse, excessive use, illegal circulation and random discharge, which increasingly cause serious public health risks and environmental pollution risks. Methadone and its main biological metabolite 2-ethylidene-1, 5-dimethyl-3, 3-diphenylpyrrolidine (EDDP) are ubiquitous in municipal wastewater, and have become typical emerging organic pollutants. Due to the low removal efficiency (<40%) of methadone by the existing wastewater treatment process, it and its metabolites are discharged into natural water bodies, which pose a potential threat to ecological health. As a stable metabolite of methadone, EDDP is often used as a biomarker in epidemiological studies of wastewater, reflecting the drug use trends of the regional population. Therefore, the detection of methadone and its metabolites in municipal wastewater and surface water not only has environmental monitoring significance, but also provides key technical support for drug control.

[0003] At present, the detection of methadone and EDDP in wastewater and surface water faces significant technical bottlenecks: the concentrations of both in wastewater and surface water are at the ng / L level, and although the mature detection technology of liquid chromatography tandem mass spectrometry has high sensitivity, it is expensive, complex to operate, and cumbersome to process samples, and is not suitable for on-site rapid detection; existing portable devices (such as colorimetric test strips, portable handheld Raman / infrared, fluorescence instruments, etc.) can be used for high-concentration sample analysis, but have insufficient sensitivity and poor anti-interference ability in trace detection under complex matrix conditions. Electrochemical sensing technology has a wide application prospect in trace pollutant detection due to its strong portability, rapid response and high sensitivity. Methadone, as an electroactive compound, can undergo oxidation reaction on a nanomaterial-modified electrode, and there have been studies on enhancing its electrochemical response in biological samples by carbon-based nanomaterials. However, such methods based on electrocatalytic mechanism are difficult to achieve high-sensitivity detection of ng / L-level concentrations of methadone in complex environmental matrices, limiting their application in environmental water bodies. Therefore, it is urgent to develop a detection technology with high sensitivity and strong selectivity to achieve efficient detection of methadone and EDDP in wastewater and surface water.

[0004] Electrochemical sensing combined with molecularly imprinted polymers (MIPs) can enhance the detection ability of trace analytes by selective adsorption, achieving high sensitivity and high selectivity detection of substances. By introducing redox probes, MIP sensors can use the binding of target substances to imprinted sites to trigger current changes, enabling indirect detection. This strategy is suitable for a variety of target substances (Li et al, Biosensors and Bioelectronics, 2024, 249:116018). Prussian blue analogues (PBA) are used as built-in redox probes and are used in conjunction with high-surface-area materials to improve imprinted efficiency and detection performance. Conductive metal-organic frameworks (MOFs) synthesized through a template sacrifice strategy not only retain their porous structure but also provide sufficient electron transport channels and reactive sites, making them ideal carriers for constructing high-performance surface molecularly imprinted electrode materials. Currently, there is no public report in the prior art of combining PBA with conductive MOF materials to construct electrochemical sensors. How to construct a redox probe built-in electrochemical sensing material with high sensitivity, high selectivity, and stability is of great significance for on-site detection of low-concentration substances in complex water environments. SUMMARY

[0005] The purpose of the present application is to address the lack of sensitivity in electrochemical detection technology for ng / L concentrations of methadone and EDDP, and to provide a copper ferrocyanide / copper benzene hexathiol composite electrode material, a preparation method and use thereof.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] In a first aspect, a copper ferrocyanide / copper benzene hexathiol electrode material is provided. The copper ferrocyanide / copper benzene hexathiol composite nanomaterial is composed of conductive MOF copper benzene hexathiol and built-in redox probe copper ferrocyanide. The copper ferrocyanide is a Prussian blue analogue that is fixed on the surface of copper benzene hexathiol through in-situ bonding, and has good conductivity and stable reversible redox properties.

[0008] In a second aspect, a preparation method for the above-mentioned copper ferrocyanide / copper benzene hexathiol electrode material is provided, comprising the following steps:

[0009] A precursor HKUST-1 MOF is synthesized by coordination reaction of a copper ion source and 1,3,5-benzene tricarboxylic acid triethylammonium salt. A copper benzene hexathiol MOF material is generated by ligand exchange reaction of benzene hexathiol and the precursor HKUST-1 MOF. The copper benzene hexathiol MOF material is reacted with potassium ferrocyanide and potassium ferrocyanide to generate and fix copper ferrocyanide in-situ through coordination bonding, and then dried to obtain the copper ferrocyanide / copper benzene hexathiol composite nanomaterial.

[0010] In some implementations, the method specifically includes the following steps:

[0011] (1) Add 1.5 mL of copper nitrate solution with a concentration of 0.08–0.12 mol / L (preferably 0.1 mol / L) to 240 mL of ethanol-water mixed solution, wherein the volume ratio of ethanol to water is (0.8–1):1 (preferably 1:1). After stirring and dissolving, add 1 mL of 1,3,5-benzenetricarboxylic acid triethylammonium salt aqueous solution with a concentration of 0.1–0.15 mol / L (preferably 0.1 mol / L). Stir the reaction for 5–10 min. After centrifugation and washing with deionized water, the reaction solution is vacuum dried at 50–70 °C for 8–24 h to obtain the precursor HKUST-1MOF of copper phenylhexathiophenol MOF.

[0012] (2) Disperse 30 mg HKUST-1 MOF obtained in step (1) in 16 mL of deoxymethanol; add 8 mL of benzene hexathiophenol deoxymethanol solution with a concentration of 3.5–5 mmol / L (preferably 4 mmol / L) and stir the reaction at room temperature for 5 h; after the reaction is completed, the product is separated by centrifugation, washed and dried under vacuum at 50–70 °C for 8–24 h to obtain copper benzene hexathiophenol MOF material;

[0013] (3) Disperse the 30 mg copper benzene hexathiophenol MOF obtained in step (2) in 75 mL of a mixed solution consisting of N,N-dimethylformamide (DMF), 30% hydrogen peroxide (H2O2) and deionized water, wherein the volume ratio of DMF:30% H2O2:water is (6-8):(1-2):3, preferably 6:1:3; add 2-6 mmol of potassium ferrocyanide and potassium ferrocyanide in a molar ratio of 1:1 to the mixed solution, stir and react at room temperature for 12 h, and centrifuge, wash and dry the product under vacuum at 50-70 °C for 8-24 h to obtain copper ferrocyanide / copper benzene hexathiophenol composite nanomaterials.

[0014] Thirdly, the copper ferrocyanide / copper hexathiophenol electrode material is further improved for preparing a molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode for recognizing methadone and EDDP. The preparation method includes the following steps:

[0015] (1) Copper ferrocyanide / copper hexathiophenol was added to an isopropanol and water dispersion containing Nafion solution and uniformly drop-coated onto the surface of a screen-printed carbon working electrode to obtain a copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode with a loading of 0.2 mg / cm³. 2 ;

[0016] (2) A 60 μL H2SO4 solution containing methadone and para-aminobenzoic acid was used as the electrolyte, wherein the molar ratio of para-aminobenzoic acid to methadone was (6-7):1, preferably 6:1, the concentration of para-aminobenzoic acid was 2-4 mmol / L, preferably 3 mmol / L, and the concentration of H2SO4 was 0.1 mol / L. Electrochemical cyclic voltammetry was used to polymerize the methadone-containing polymer / copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode, with a voltage range of -0.2–1.2 V and a scan rate of 50 mV·s. -1 The number of aggregation circles is 5;

[0017] (3) Elution of template molecules: 60 μL of methanol aqueous solution (66.7 vol%) was added dropwise to the polymer / copper ferrocyanide / copper hexathiophenol / screen printed electrode obtained in step (2) to elute methadone. The elution time was 1-1.5 min. The eluted electrode was washed with deionized water and dried at 25 °C to obtain molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen printed carbon electrode.

[0018] Fourthly, the aforementioned molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode can be used to construct an electrochemical sensor for detecting methadone and its main metabolite EDDP in water. Specifically, the molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode serves as the working electrode, while the carbon electrode and Ag / AgCl electrode serve as the counter and reference electrodes, respectively. Differential pulse voltammetry is used for determination; by measuring the change in the voltammetric peak current before and after adsorption of the target substance, quantitative analysis of methadone and its metabolites is achieved.

[0019] The beneficial effects of this invention are that the copper ferrocyanide / copper hexathiophenol composite material prepared by this invention has both excellent conductivity and stable built-in redox probe, which can serve as an efficient carrier for molecularly imprinted electrochemical sensors, significantly improving detection sensitivity and enabling accurate detection of ng / L methadone and its metabolite EDDP. It is suitable for drug monitoring in wastewater epidemiology and trace analysis of environmental pollutants, and has good practical application prospects. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0021] Figure 1 The following are the (a) XRD and (b) Raman spectra of the precursors HKUST-1, copper hexathiophenol, and copper ferrocyanide / copper hexathiophenol-3 in Example 1 of this invention.

[0022] Figure 2 SEM images of (a) HKUST-1 and (b) copper hexathiophenol in Example 1;

[0023] Figure 3 The electrochemical performance of copper ferrocyanide / copper hexathiophenol in Example 1 is shown in Figure 1. (a) is the CV curve of the electrodes prepared by copper hexathiophenol, copper ferrocyanide / copper hexathiophenol-1, copper ferrocyanide / copper hexathiophenol-2 and copper ferrocyanide / copper hexathiophenol-3 in 0.1 mol / L KCl aqueous electrolyte, and (b) is the CV curve of the copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode after 80 cycles of testing.

[0024] Figure 4 SEM images of the molecularly imprinted / copper ferrocyanide / copper hexathiophenol in Example 2; (a) scale bar is 300 nm, (b) scale bar is 100 nm;

[0025] Figure 5 The following are the signal response diagrams of the sensor in Example 2: (a) is a schematic diagram of the sensor's signal response; (b) is a DPV diagram of the sensor after adsorbing different concentrations of EDDP; and (c) is a standard curve showing the change of the response signal ΔI with the lg value of methadone and EDDP concentrations.

[0026] Figure 6 The graph shows the test results of (a) anti-interference and (b) stability of the sensor in Example 2. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0028] Example 1

[0029] The preparation and electrochemical characterization of a copper ferrocyanide / copper hexathiophenol electrode material includes the following steps:

[0030] (1) 1.5 mL of 0.1 mol / L copper nitrate solution was added to 240 mL of ethanol-water mixed solution (ethanol to water volume ratio of 1:1). After stirring and dissolving, 1 mL of 0.1 mol / L triethylammonium salt of 1,3,5-benzenetricarboxylic acid (synthesis method is described in Liu et al, CrystEngComm, 2016, 18, 4127-4132) aqueous solution was added. The reaction was stirred for 6 min. After centrifugation and washing with deionized water, the reaction solution was dried under vacuum at 60 °C for 8 h to obtain the precursor HKUST-1MOF of copper benzene hexathiophenol MOF.

[0031] (2) Disperse 30 mg HKUST-1 MOF obtained in step (1) in 16 mL of deoxyethanol; add 8 mL of 4 mmol / L benzene hexathiophenol deoxyethanol solution to it, stir and react for 5 h at room temperature; after the reaction is completed, the product is separated by centrifugation, washed, and vacuum dried at 60 °C for 8 h to obtain copper benzene hexathiophenol MOF material.

[0032] (3) Disperse the 30 mg copper benzene hexathiophenol MOF obtained in step (2) in a 75 mL mixed solution composed of DMF, 30% H2O2 and deionized water, wherein the volume ratio of DMF: 30% H2O2: water is 6:1:3; add 2, 4 and 6 mmol of potassium ferrocyanide and potassium ferrocyanide to the mixed solution respectively, with a molar ratio of 1:1, stir and react at room temperature for 12 h, and the resulting product is centrifuged, washed and dried under vacuum at 60 °C for 8 h to obtain copper ferrocyanide / copper benzene hexathiophenol composite nanomaterials, which are named copper ferrocyanide / copper benzene hexathiophenol-1, copper ferrocyanide / copper benzene hexathiophenol-2 and copper ferrocyanide / copper benzene hexathiophenol-3.

[0033] (4) 2.5 mg of copper ferrocyanide / copper hexathiophenol was added to 1 mL of a 50 vol% isopropanol aqueous solution containing 0.1 wt.% Nafion, and then uniformly drop-coated onto the surface of a screen-printed carbon working electrode to obtain a copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode with a loading of 0.2 mg / cm³. 2 .

[0034] Figure 1 The XRD and Raman spectra of precursors HKUST-1, copper hexathiophenol, and copper ferrocyanide / copper hexathiophenol-3 are shown. Their characteristic peaks indicate successful preparation of HKUST-1, copper hexathiophenol, and copper ferrocyanide / copper hexathiophenol-3. After the formation of copper ferrocyanide / copper hexathiophenol-3, the Raman spectrum retains the characteristic peak of copper hexathiophenol, and the peak is located at 2111.5 cm⁻¹. -1 A distinct Fe-C≡N stretching vibration peak was observed. Combined with the XRD results, the copper ferrocyanide / copper hexathiophenol composite structure retained the copper hexathiophenol structure, and the Cu element in copper hexathiophenol served as a Cu source in [Fe(CN)6]. 3– / 4– The bonds formed copper ferrocyanide.

[0035] Figure 2 The images show SEM images of HKUST-1 and copper hexathiophenol. HKUST-1 is a cube with a side length of 300 nm and a smooth surface. The copper hexathiophenol formed after the reaction also exhibits a cubic shape, consistent with the particle size of the precursor, and has a rough surface.

[0036] Figure 3Electrochemical cyclic voltammetry (CV) of copper ferrocyanide / copper hexathiophenol. (a) CV curves of electrodes prepared with copper hexathiophenol, copper ferrocyanide / copper hexathiophenol-1, copper ferrocyanide / copper hexathiophenol-2, and copper ferrocyanide / copper hexathiophenol-3 in 0.1 mol / L KCl aqueous electrolyte. Compared with copper hexathiophenol, copper ferrocyanide / copper hexathiophenol exhibits a pair of reversible redox peaks at 0.6 V. Furthermore, the CV peak current increases with increasing concentrations of potassium ferrocyanide and potassium ferrocyanide in the reaction, indicating that copper ferrocyanide / copper hexathiophenol-3 possesses good conductivity and reversible redox properties. (b) CV curve of the copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode after 80 cycles of testing. The CV curve almost overlaps with the initial CV curve, indicating stable electrochemical reversible redox properties.

[0037] Example 2

[0038] In Example 1, a molecularly imprinted / copper hexathiophenol / screen-printed carbon working electrode was prepared using a copper ferrocyanide / copper hexathiophenol-3 / screen-printed carbon working electrode. The specific steps are as follows:

[0039] (1) A 0.1 mol / L H2SO4 solution containing methadone and 3 mmol / L p-aminobenzoic acid was used as the electrolyte, with a molar ratio of p-aminobenzoic acid to methadone of 6:1. Electrochemical cyclic voltammetry was used for polymerization to obtain a polymer containing methadone / copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode with a voltage range of -0.2–1.2 V and a scan rate of 50 mV·s. -1 The number of aggregation circles is 5;

[0040] (2) 60 μL of methanol aqueous solution (66.7 vol%) was added dropwise to the polymer / copper ferrocyanide / copper hexathiophenol / screen printed electrode obtained in step 1 to elute the template molecule methadone for 1 min. The eluted electrode was washed with deionized water and dried at 25 °C to obtain the molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen printed carbon electrode.

[0041] An electrochemical sensor was constructed using a molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode as the working electrode, and an Ag / AgCl electrode as the counter electrode and reference electrode, respectively. A 60 μL solution of 0.1 mol / L KCl was used as the electrolyte. The peak current difference ΔI before and after adsorption of medazine or EDDP in the water was measured by differential pulse voltammetry. ΔI showed a two-segment linear correlation with lgC.

[0042] Figure 4The image shows a SEM image of molecularly imprinted copper ferrocyanide / copper hexathiophenol. Some parts of the image exhibit a complete cubic structure, while others show pores on their surface. This may be due to the localized consumption of copper hexathiophenol, which leads to the partial loss of copper ferrocyanide / copper hexathiophenol. The detached copper ferrocyanide / copper hexathiophenol then forms a loose, porous structure composed of granules.

[0043] Figure 5 This is the signal response graph of the sensor. As the adsorbed EDDP concentration increases, the DPV peak current decreases, and the methadone concentration C ranges from 10... -9 -10 -3 mol / L, detection limit is 10.6 × 10⁻⁶ -12 mol / L, or 3.28 ng / L; the concentration C of EDDP is in the range of 10 mol / L. -11 -10 -3 mol / L, detection limit is 3.6 × 10⁻⁶ -13 The concentration is mol / L, or 99.86 pg / L. This indicates that the electrochemical sensor has high sensitivity for the detection of methadone and EDDP.

[0044] Figure 6 The sensor's anti-interference and stability were demonstrated. Interference tests were conducted using hydrochloric acid (HCl), sodium hydroxide (NaOH), potassium chloride (KCl), sodium sulfate (Na2SO4), humic acid, glucose, sodium dodecylbenzenesulfonate (SDBS), and diatomite. When the concentration of the interfering agent was 10 times that of the target analyte (HCl, NaOH, KCl, Na2SO4, glucose, and SDBS: 100 μM; humic acid and diatomite: 1 g / L; methadone and EDDP: 10 μM), the response current significantly increased in the presence of methadone or EDDP, indicating good specificity for methadone and EDDP. The electrode was vacuum-preserved at room temperature, and the electrochemical response signal of the sensor to EDDP was recorded over 7 weeks. The RSD was 1.30%, demonstrating the sensor's good stability.

[0045] Example 3: Performance Evaluation of Electrochemical Sensor

[0046] To evaluate the sensor's performance in practical applications, actual water samples from municipal wastewater treatment plants and rivers were selected, and the samples filtered through 0.45 μm glass fiber membranes were tested. The detection results of EDDP and methadone-spiked samples are summarized in Table 1.

[0047] Table 1. Detection results of EDDP and methadone in domestic sewage and river water

[0048]

[0049] For filtered wastewater and river water samples, the recoveries of EDDP were 104.5% and 102.0%, respectively, with relative standard deviations (RSDs) below 5.0%. In contrast, the recoveries of methadone were 110.5% and 103.0%, respectively, with RSDs also below 5.0%. These results indicate that, under conditions of reduced matrix interference, the sensor exhibits high detection accuracy and repeatability, demonstrating potential for practical applications.

Claims

1. A copper ferrocyanide / copper hexathiophenol electrode material, characterized in that, The copper ferrocyanide / copper hexathiophenol electrode material is composed of a conductive metal-organic framework and an embedded redox probe. The conductive metal-organic framework is made of copper hexathiophenol, and the embedded redox probe is made of copper ferrocyanide. The copper ferrocyanide is fixed on the surface of copper hexathiophenol by in-situ bonding.

2. A method for preparing the copper ferrocyanide / copper hexathiophenol electrode material according to claim 1, characterized in that, Includes the following steps: The precursor HKUST-1MOF was synthesized by coordination reaction between a copper ion source and triethylammonium salt of 1,3,5-benzenetricarboxylic acid. A copper-benzene-hexathiophenol MOF material was generated by ligand exchange reaction between benzene-hexathiophenol and the precursor HKUST-1MOF. The copper-benzene-hexathiophenol MOF material was then reacted with potassium ferrocyanide and potassium ferrocyanide to generate and fix copper ferrocyanide in situ through coordination bonding. After drying, a copper ferrocyanide / copper-benzene-hexathiophenol composite nanomaterial was obtained.

3. The method for preparing the copper ferrocyanide / copper hexathiophenol electrode material according to claim 2, characterized in that, The coordination reaction via a copper ion source and triethylammonium 1,3,5-benzenetricarboxylate includes the following steps: 1.5 mL of a 0.08–0.12 mol / L copper nitrate solution is added to 240 mL of an ethanol-water mixture, wherein the volume ratio of ethanol to water is (0.8–1):

1. After stirring to dissolve, 1 mL of a 0.1–0.15 mol / L aqueous solution of triethylammonium 1,3,5-benzenetricarboxylate is added. The mixture is stirred for 5–10 min, and the reaction solution is centrifuged, washed, and dried.

4. The method for preparing the copper ferrocyanide / copper hexathiophenol electrode material according to claim 2, characterized in that, The ligand exchange reaction using benzene hexathiophenol and the precursor HKUST-1MOF includes the following steps: 30 mg of HKUST-1MOF is dispersed in 16 mL of deoxymethanol; 8 mL of benzene hexathiophenol deoxymethanol solution with a concentration of 3.5–5 mmol / L is added, and the mixture is stirred at room temperature for 5 h; after the reaction is completed, the product is centrifuged, washed, and dried.

5. The method for preparing the copper ferrocyanide / copper hexathiophenol electrode material according to claim 2, characterized in that, The copper phenyl hexathiophenol MOF material reacts with potassium ferricyanide and potassium ferrocyanide to generate and fix copper ferrocyanide in situ through coordination bonding, including the following steps: 30 mg of copper phenyl hexathiophenol MOF is dispersed in 75 mL of a mixed solution composed of DMF, 30% H2O2 and water, wherein the volume ratio of DMF:30% H2O2:water is (6-8):(1-2):3; 2-6 mmol of potassium ferricyanide and potassium ferrocyanide are added to the mixed solution in a molar ratio of 1:1, and the mixture is stirred at room temperature for 12 h. The resulting product is then centrifuged, washed, and dried.

6. The method for preparing the copper ferrocyanide / copper hexathiophenol electrode material according to any one of claims 2-5, characterized in that, The drying process involves vacuum drying at 50–70°C for 8–24 hours.

7. A molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode for identifying methadone and EDDP, characterized in that, It is prepared through the following steps: (1) The copper ferrocyanide / copper hexathiophenol electrode material of claim 1 was added to a Nafion dispersion and uniformly drop-coated onto the surface of a screen-printed carbon electrode to obtain a copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode with a loading of 0.2 mg / cm³. 2 ; (2) Using an H2SO4 solution containing methadone and para-aminobenzoic acid as the electrolyte, polymerization was carried out by electrochemical cyclic voltammetry to obtain a polymer containing methadone / copper ferrocyanide / copper hexathiophenol / screen-printed carbon working electrode with a voltage range of -0.2–1.2V and a scan rate of 50mV·s. -1 The number of aggregation circles is 5; (3) Elute the template molecules, wash the eluted electrode with water, and dry it to obtain a molecularly imprinted / copper ferrocyanide / copper benzene hexathiophenol / screen printed carbon electrode.

8. The molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode according to claim 7, characterized in that, In step (2), the molar ratio of para-aminobenzoic acid to methadone is (6-7):1, the concentration of para-aminobenzoic acid is 2-4 mmol / L, and the concentration of H2SO4 is 0.1 mol / L.

9. The molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode according to claim 7, characterized in that, In step (3), 60 μL of methanol aqueous solution with a concentration of 66.7 vol% is added dropwise to the obtained polymer / copper ferrocyanide / copper hexathiophenol / screen printed electrode to elute methadone for 1-1.5 min; the drying is carried out at 25 °C.

10. The use of the molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode of claim 7 in the identification of methadone and EDDP, characterized in that, Using a molecularly imprinted / copper ferrocyanide / copper hexathiophenol / screen-printed carbon electrode as the working electrode, and an Ag / AgCl electrode as the counter electrode and reference electrode, differential pulse voltammetry was employed to quantitatively determine medazone and its metabolite EDDP in domestic sewage and river water.

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