Methcathinone imprinted electrochemical sensor as well as preparation method and detection method thereof

Abstract

The invention provides a methcathinone imprinted electrochemical sensor as well as a preparation method and a detection method thereof, and relates to an electrochemical sensor technology. According to the methcathinone imprinted electrochemical sensor, o-phenylenediamine is taken as a polymeric monomer, methcathinone is taken as a template molecule, a methcathinone imprinted membrane is prepared by adopting an electropolymerization mode, and then the methcathinone imprinted membrane is subjected to potential elution in an HCl dilute solution, so that the methcathinone imprinted electrochemical sensor is obtained. The methcathinone imprinted electrochemical sensor capable of detecting methcathinone in a simply treated aqueous solution is prepared, and indirect detection of methcathinone is realized. The sensor is simple to prepare and high in sensitivity, the detection limit can reach 1.0 * 10 <-12 > mol.L <-1 >, the detection range is 1.0 * 10 <-12 >-1.0 * 10 <-4 > mol.L <-1 >, on-site rapid detection of methcathinone can be realized, and a choice is provided for more efficient and rapid inspection and analysis of basic-level public security drugs.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical sensors, and in particular to a methcathinone imprinted electrochemical sensor and a preparation method and a detection method thereof. Background Art

[0002] Methcathinone (MC) is a new psychoactive substance that is widely abused worldwide due to its low price, easy availability and significant neurostimulant effect, which seriously threatens people's physical and mental health and social stability. Therefore, it is of great research significance to quickly and accurately detect methcathinone.

[0003] In the prior art, methcathinone content in urine or liver is usually determined by liquid chromatography-mass spectrometry or gas chromatography-mass spectrometry, such as ultra-high performance liquid chromatography-mass spectrometry (UPC2-MS, with a minimum detection limit of 0.5 ng·mL -1 ), high performance liquid chromatography-mass spectrometry (HPLC-MS / MS, with a minimum detection limit of 0.1 ng·mL -1 ) for separation and detection, but the above methods are expensive, technically demanding, and not suitable for rapid on-site detection. In addition, some researchers have proposed the use of graphene-modified screen-printed electrodes (GSPE) for electrochemical analysis of methcathinone, with a minimum detection limit of 11.60 µg mL -1 This method is fast and accurate, but has a high detection limit. However, all of the above detection methods require tedious pre-processing steps, strict professional training requirements for personnel, and high operating and maintenance costs for the instruments, which largely limits their practical application in daily law enforcement by grassroots police officers.

[0004] At present, with the advancement of science and technology and the improvement of people's requirements for analytical accuracy, electrochemical detection methods have emerged, which can establish a certain connection between the chemical amount of the analyte and the considerable electrical signal, thereby directly or indirectly detecting the chemical amount of the analyte through the change of the electrical signal. Compared with other methods, electrochemical detection methods have the advantages of reducing the cost of use and the operating threshold. However, due to the poor electrochemical activity of methcathinone and the lack of direct redox peaks in the electrochemical window of the electrode, there are still difficulties in the rapid detection of methcathinone using electrochemical methods. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention uses o-phenylenediamine as a polymerization monomer and MC as a template molecule, and prepares an MC imprinted membrane by electropolymerization. After potential elution in a dilute HCl solution, an imprinted electrochemical sensor that can directly detect MC in a simply treated aqueous solution is prepared.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a method for preparing a methcathinone imprinted electrochemical sensor, comprising the following steps: Preparation of methcathinone imprinting prepolymer solution: dissolving functional monomer o-phenylenediamine in an acidic buffer solution and ultrasonically dissolving the solution, then adding methcathinone solution and continuing ultrasonication to obtain methcathinone imprinting prepolymer solution; Preparation of methcathinone imprinted polymer membrane: vertically suspending the three-electrode system and placing it in a methcathinone imprinted prepolymer solution for polymerization to obtain a methcathinone imprinted polymer membrane; Preparation of methcathinone imprinted electrochemical sensor: placing a three-electrode system covered with methcathinone imprinted polymer film in a hydrochloric acid eluent for stirring elution at an elution voltage of -0.1 to -0.3 V to obtain a methcathinone imprinted electrochemical sensor.

[0007] Furthermore, the feed ratio of o-phenylenediamine and acidic buffer solution is 0.10mmol:5mL; The addition amount of the methcathinone solution and the feeding ratio of o-phenylenediamine are 50-70 μL: 0.01 mmol, wherein the concentration of the methcathinone solution is 0.25 mol·L -1 .

[0008] Furthermore, the acidic buffer is a HAc-NaAc buffer with a pH of 5-5.6, preferably 5.2.

[0009] Furthermore, the three-electrode system is composed of a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a Pt wire electrode as an auxiliary electrode; Before use, the glassy carbon electrode is ground by mixing alumina powder of different particle sizes with deionized water until the glassy carbon electrode is at K 3 [Fe(CN) 6 ]The redox peak difference in the solution is within 100mV.

[0010] Furthermore, the number of polymerization cycles is 20-40 cycles, preferably 30 cycles.

[0011] Furthermore, the hydrochloric acid eluent is 0.6 mol·L -1 HCl solution; The elution time is 10-30 min, preferably 20 min.

[0012] In a second aspect, the present invention provides a methcathinone imprinted electrochemical sensor prepared by the method described above.

[0013] In a third aspect, the present invention provides a method for detecting methcathinone, which is performed by using a methcathinone imprinted electrochemical sensor prepared by the method described above.

[0014] Furthermore, the detection method comprises the following steps: Different concentrations of methcathinone solutions were prepared and measured using differential pulse voltammetry to obtain a DPV curve. The response current of DPV was linearly fitted to the concentration of methcathinone to obtain the methcathinone standard curve; Using potassium ferrocyanide as a probe and the methcathinone imprinted electrochemical sensor to detect a sample containing methcathinone, and obtaining a sample response peak change current of methcathinone; The content of methcathinone was calculated based on the sample response peak change current of methcathinone and the methcathinone standard curve.

[0015] Furthermore, in the process of detecting a sample containing methcathinone using the methcathinone imprinted electrochemical sensor, the sample containing methcathinone is added to a potassium ferrocyanide solution and a methcathinone imprinted electrochemical sensor for incubation and then detected.

[0016] Furthermore, the incubation time is 4-6 minutes, preferably 5 minutes.

[0017] The methcathinone imprinted electrochemical sensor and its preparation method and detection method provided by the present invention have the following advantages compared with the prior art: The present invention uses o-phenylenediamine as a polymerization monomer and methcathinone as a template molecule to prepare a methcathinone imprinted membrane by electropolymerization. After potential elution in a dilute HCl solution, a methcathinone imprinted electrochemical sensor (MC-MIM / GCE) capable of detecting methcathinone in a simply treated aqueous solution is prepared, thereby realizing indirect detection of methcathinone. The sensor is simple to prepare, has high sensitivity, and a detection limit of up to 1.0×10 -12 mol·L -1 , the detection range is 1.0×10 -12 -1.0×10 -4 mol·L -1 .

[0018] The detection method of methcathinone proposed in the present invention uses small molecule potassium ferrocyanide as a probe and uses a methcathinone imprinted electrochemical sensor for post-incubation detection. When a certain amount of MC is contained in the sample solution to be tested, it will specifically block the imprinted holes, resulting in a decrease in the redox peak current of the probe, thereby establishing a linear relationship between the response current and the methcathinone concentration, thereby realizing indirect detection of the object to be tested. This method is expected to achieve on-site rapid detection of methcathinone, make up for the high detection cost, lack of experimental technology and equipment of grassroots front-line police officers, and provide a more efficient and quick option for the inspection and analysis of public security drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The peak current response diagram of MC-MIM / GCE prepared in Examples 1 and 2 of the present invention and added with different amounts of methcathinone solution is shown; Figure 2 The results show that 1×10 -12 mol·L -1 The peak current response results of MC in MC-MIM / GCE; Figure 3 The DPV curve (a) and the linear relationship diagram (b) of MC-MIM / GCE in Example 5 of the present invention after incubation in MC solutions of different concentrations are shown; Figure 4 The DPV response diagrams of the methcathinone imprinted polymer membrane and the methcathinone non-imprinted polymer membrane before and after elution in Test Example 1 of the present invention are shown; Figure 5 SEM images of a non-imprinted membrane before elution (a), after elution (b) and an imprinted membrane before elution (c), after elution (d) in an embodiment of the present invention are shown; Figure 6 A graph showing the change in potassium ferrocyanide peak current of the methcathinone imprinted electrochemical sensor after incubation in methcathinone, γ-hydroxybutyric acid, heroin, morphine, methamphetamine, methadone, and fentanyl. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The following examples respectively describe in detail the preparation conditions, detection conditions and detection performance of the methcathinone imprinted electrochemical sensor provided by the present invention. Unless otherwise specified, the raw materials used in the examples are all common commercially available raw materials.

[0023] Racemic methcathinone hydrochloride (ω = 97.3% ± 0.6%, National Narcotics Laboratory, Narcotics Control Bureau, Ministry of Public Security, used to prepare MC solution); potassium ferrocyanide (K 3 [Fe(CN) 6 ], ω≥99% Beijing Chemical Plant); Potassium chloride (KCl), ω≥99.5%, Xilong Science Co., Ltd.; Alumina (Al 2 O 3 ), ω≥99%, Tianjin Aida Hengsheng Technology Co., Ltd.; o-phenylenediamine (o-PD), ω≥99%, Shanghai Titan Sclentific Co; anhydrous sodium acetate (CH 3 COONa), ω≥99%, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.; Acetic acid (CH 3 COOH), ω≥99%, Shanghai Shenbo Chemical Co., Ltd.; hydrochloric acid (HCl), 36-38%; Xilong Scientific Co., Ltd. Embodiment 1:

[0024] In this embodiment, o-phenylenediamine is used as a functional monomer to prepare a methcathinone imprinted electrochemical sensor, which specifically includes the following steps: S1, treatment of bare glassy carbon electrode: grinding the glassy carbon electrode (GCE) by mixing alumina powder of different particle sizes with deionized water; Specifically, on a wet artificial suede, a glassy carbon electrode was polished in sequence with 1.0 and 0.5 μm aluminum oxide powders from coarse to fine in an "8" shape until the surface was smooth.

[0025] During the grinding process, it is necessary to pay attention to whether the force on the glassy carbon electrode is uniform and whether the surface of the glassy carbon electrode is in full contact with the suede; the aluminum oxide powder is diluted with deionized water, and the degree of dilution is determined according to the viscosity of the aluminum oxide powder. If the aluminum oxide powder is viscous, it is appropriately diluted with deionized water, and the powder stuck on the electrode is rinsed; if the aluminum oxide powder is too diluted and has no grinding effect, some aluminum oxide powder is appropriately added. Then, the glassy carbon electrode is ultrasonically cleaned with deionized water for 10 seconds to wash away the aluminum oxide powder and impurities, and the residual water stains are carefully absorbed around the electrode with filter paper. Finally, the glassy carbon electrode is placed in 5.0mmol·L -1 K 3 [Fe(CN) 6 ] (containing 0.1 mol·L -1 Cyclic voltammetry (CV) scanning was performed in KCl) solution until the redox peak difference was within 100 mV to meet the detection standard, otherwise it was re-polished.

[0026] S2, preparation of methcathinone imprinting prepolymer solution: accurately weigh 0.10 mmol of functional monomer o-PD using a balance and dissolve it in 5 mL of HAc-NaAc buffer solution with pH = 5.2 (Hac and NaAc concentrations are 0.2 mol·L -1 ), ultrasonic for 2 min to allow o-PD to fully dissolve in the solution, and add 60 μL of 0.25 mol·L -1 The MC solution was then ultrasonicated for 2 min to allow the template MC to interact with the functional monomer to obtain the methcathinone imprinting prepolymer solution.

[0027] In some embodiments of the present invention, the pH of the HAc-NaAc buffer solution is 5.0, 5.3, 5.4, 5.5, and 5.6, and the methcathinone imprinting prepolymer solution can be successfully obtained, and the optimal pH is 5.2.

[0028] S3, preparation of methcathinone imprinted polymer film: a three-electrode system consisting of a polished glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a Pt wire electrode as an auxiliary electrode was placed vertically in the methcathinone imprinted prepolymer solution, and polymerized by cyclic voltammetry (CV) scanning for 30 cycles, wherein the scanning range was 0-0.8V and the scanning rate was 50mVs -1 .

[0029] S4, preparation of methcathinone imprinted electrochemical sensor: After the polymerization is completed, the three-electrode system covered with the methcathinone imprinted polymer film is rinsed with deionized water, and the filter paper absorbs the water stains and is vertically suspended in 0.6 mol·L -1 In HCl solution, a voltage of -0.3 V was applied to the working electrode and stirred for 20 min to remove the template molecules in the methcathinone imprinted polymer film to obtain the methcathinone imprinted electrochemical sensor (MC-MIM / GCE).

[0030] At the same time, it was found in this example that when HCl was selected as the eluent, the concentration of HCl was 0.1-0.6 mol·L -1 There is still no effect, but the solution concentration has reached the maximum concentration for eluting metal ions, so at 0.6 mol·L -1 A voltage was applied to the working electrode under stirring conditions in HCl. It was found that the MC molecules in the template could be effectively removed from -0.1V to -0.3V. The reason may be that the application of voltage changed the potential of the methcathinone imprinted polymer film, thereby effectively destroying the complementary structure of MC and o-PD. Embodiment 2:

[0031] The methcathinone imprinted electrochemical sensor was prepared according to the method of Example 1, except that the amount of template molecule added in step S2 was adjusted to 0.25 mol·L -1MC-MIM / GC was prepared with 40 µL and 80 µL of MC solution.

[0032] The MC-MIM / GC obtained in this example and the MC-MIM / GC obtained in Example 1 were mixed in 5.0 mmol·L -1 K 3 [Fe(CN) 6 ] (containing 0.1 mol·L -1 The test was carried out in KCl solution.

[0033] The results are as follows Figure 1 As shown, it can be seen that the corresponding peak current of the potassium ferrocyanide probe first increases and then decreases. This may be because when the template concentration is insufficient, not enough imprint holes can be formed, and when the template is excessive, there are not enough monomers to form imprint holes with it. In addition, when o-PD is excessive, it will induce high cross-linking, resulting in the formation of an imprinted membrane that is too thick, making it difficult for the template molecules to be eluted and difficult to approach the imprinted holes. Therefore, the amount of o-PD was selected as 0.10mmol, and the amount of template added was 60μL0.25mol·L -1 MC solution. Embodiment 3:

[0034] The methcathinone imprinted polymer membrane was prepared according to the method of Example 1, except that the number of polymerization cycles in step S3 was set to 15 cycles and 50 cycles, respectively. The MC-MIM / GC obtained by scanning polymerization for 30 cycles in Example 1 was 5.0 mmol·L -1 K 3 [Fe(CN) 6 ](Contains 0.1mol·L -1 DPV test was carried out in KCl solution.

[0035] The test results are as follows: When the number of polymerization turns is 15, there is still a large current. When the number of polymerization turns is 30, the peak current drops to 8.934×10 -3 µA, indicating that a non-conductive polymer film has been formed on the electrode surface. It is non-conductive after 50 cycles of polymerization. However, because the thickness of the polymer film is determined by the number of cycles of polymerization, although it is non-conductive after 50 cycles of polymerization, the polymer film will be very thick at this time. The thickness of the film is related to the sensitivity and elution conditions. Therefore, 30 cycles is set as the optimal number of cycles of polymerization, which not only ensures the stability of the polymer film, but also achieves the best detection effect. Embodiment 4:

[0036] The methcathinone imprinted electrochemical sensor was prepared according to the method of Example 1, except that the hydrochloric acid eluent was replaced with deionized water, pure methanol, pure ethanol, and a mixed solution of methanol:acetic acid (9:1), and the MC-MIM / GCE was stirred and eluted. The obtained MC-MIM / GC was heated to 5.0 mmol·L every five minutes. -1 K 3 [Fe(CN) 6 ] (containing 0.1 mol·L - 1 DPV test was carried out in KCl solution.

[0037] The results showed that when deionized water was used as the eluent, the elution time was 80 minutes or even stirred overnight, and the DPV scanning of MC-MIM / GCE in the potassium ferrocyanide electrolytic cell did not produce redox peaks. Using pure methanol, pure ethanol, and a mixed solution of methanol: acetic acid (9:1) as the eluent also had no effect.

[0038] Combined with the conclusions of hydrochloric acid concentration and elution voltage in Example 1, the optimal elution condition determined in the present invention is that the eluent is 0.6 mol·L -1 HCl, elution voltage -0.3V, elution time 20min. Embodiment 5:

[0039] This embodiment provides a method for detecting methcathinone, specifically using differential pulse voltammetry (DPV) to measure MC, with K 3 [Fe(CN) 6 ] as a probe using the methcathinone imprinted electrochemical sensor prepared in Example 1 to detect samples containing, the specific process is as follows: Using the three-electrode system in Example 1, a 1.0×10 -12 mol·L -1 5mL of MC5.0mmol·L -1 K 3 [Fe(CN) 6 ] (containing 0.1 mol·L -1 In a KCl solution, the MC-MIM / GCE prepared in Example 1 was placed vertically in the air as a working electrode for incubation, and the DPV response current was measured. In this example, the incubation time was optimized, and the results were as follows. Figure 2 As shown in the figure, as the stirring incubation time increases, the peak current keeps decreasing until after 5 minutes, when the downward trend slows down and becomes stable. Therefore, 5 minutes is set as the optimal incubation time. After 5 minutes, the peak current is more stable, but it will undoubtedly increase the experimental cost and is not conducive to public security practice. Therefore, in this embodiment, the optimal incubation time is selected as 5 minutes.

[0040] The optimal incubation time was 5 min and the process was as follows: Prepare MC solutions of different concentrations for DPV measurement to obtain a DPV curve. In this embodiment, the DPV curve is as follows: Figure 3 As shown in (a), as the MC concentration increases, the DPV peak current response on MC-MIM / GCE becomes lower and lower, indicating that the MC molecules in the potassium ferrocyanide solution system continuously fill the holes on the molecular imprinting membrane and block the conduction of current.

[0041] The response current of DPV was linearly fitted to the concentration c of MC, and the linear relationship was as follows: Figure 3 As shown in (b), it can be seen that the DPV response current is related to the concentration of MC at 1.0×10 -12 -1.0×10 -4 mol·L -1 There is a linear relationship within the concentration range, and the corresponding regression equation is ∆i=1.723logc+9.078(R 2 =0.9983), and the detection limit was 1.0×10 -12 mol·L -1 . This equation shows that there is a good linear relationship between the ∆i value and the concentration of the MC solution; The concentration of the MC solution was calculated based on the measured ∆i value to determine its content.

[0042] Comparative Example 1:

[0043] A methcathinone molecular non-imprinting electrochemical sensor was prepared according to the method of Example 1, except that the step of adding the MC solution was removed in step S2 of Example 1, a methcathinone non-imprinting polymer liquid membrane was obtained in S3, and a methcathinone non-imprinting electrochemical sensor (NIM / GCE) was obtained in step S4.

[0044] Test Example 1:

[0045] The methcathinone imprinted polymer membrane prepared in Example 1 and the methcathinone non-imprinted polymer membrane prepared in Comparative Example 1 were electrochemically characterized by comparing the methcathinone imprinted polymer membrane and the methcathinone non-imprinted polymer membrane before and after elution at 5 mL 5.0 mmol·L -1 K 3 [Fe(CN) 6 ] (containing 0.1 mol·L -1 DPV response effect in KCl solution.

[0046] The results are as follows Figure 4As shown in the figure, it can be seen that neither the uneluted methcathinone imprinted polymer membrane nor the methcathinone non-imprinted polymer membrane before and after elution can produce redox peaks in the potassium ferrocyanide solution system, indicating that the uneluted methcathinone imprinted polymer membrane and the methcathinone non-imprinted polymer membrane before and after elution both exhibit highly dense and insulating properties. No [Fe(CN)6] 3- / 4- After elution, the methcathinone-imprinted polymer membrane showed a significant redox peak, indicating that a large number of MC pores were generated during the elution process, which allowed [Fe(CN)6] 3- / 4- Able to effectively penetrate and initiate redox reactions.

[0047] Test Example 2:

[0048] According to the method of Example 1, an eluted methcathinone imprinted polymer membrane and an uneluted methcathinone imprinted polymer membrane were prepared respectively, and according to the method of Comparative Example 1, an eluted methcathinone non-imprinted polymer membrane and an uneluted methcathinone non-imprinted polymer membrane were prepared respectively, and the above four polymer membranes were characterized by scanning electron microscopy.

[0049] The results are as follows Figure 5 As shown, it can be seen that the methcathinone non-imprinted polymer membranes a and b and the methcathinone imprinted polymer membrane c before and after elution are all dense membranes, indicating that the membrane structure is not destroyed during the elution process. After elution, the methcathinone non-imprinted polymer membrane d appears loose granular, with a texture like a wrinkled sponge, from the upper left to the lower right. Obviously, the loose and porous structure of the imprinted membrane after elution is the reason why the detection sensitivity of MC-MIM / GCE to methcathinone molecules can be improved.

[0050] Test Example 3:

[0051] DPV detection was performed on the MC-MIM / GCE prepared in Example 1 and the NIM / GCE prepared in Comparative Example 1. The results showed that no peak current appeared, indicating that the optimal elution conditions selected would only elute the MC template molecules, and the imprinted membrane obtained by elution was specifically passed through the methcathinone molecules.

[0052] The specificity of MC-MIM / GCE was verified as follows: In 5mL5.0mmol·L -1 K 3 [Fe(CN) 6 ] (containing 0.1 mol·L -1 KCl) solution, and then add 1.0×10 -10 mol·L -1 MC (a), 1.0×10 -9 mol·L-1 γ-hydroxybutyrate (b), heroin (c), morphine (d), methamphetamine (e), methadone (f), and fentanyl (g), and the potassium ferrocyanide peak current was measured after MC-MIM / GCE was incubated in these solutions.

[0053] The results are as follows Figure 6 As shown in Figure 2, MC caused the peak current of potassium ferrocyanide to drop by much more than 1.0×10 -9 mol·L -1 γ-hydroxybutyric acid (b), heroin (c), morphine (d), methamphetamine (e), methadone (f), and fentanyl (g), indicating that the prepared MC-MIM / GCE has good MC-specific recognition ability.

[0054] Test Example 4:

[0055] Reproducibility and stability of MC-MIM / GCE: Five MC-MIM / GCEs were prepared using the experimental method of Example 1, and then 1.0×10 -12 mol·L -1 For the MC standard sample, the relative standard deviation of the peak current was 3.2%; after eluting the same MC-MIM / GCE to the maximum peak, the peak current was tested 5 times in parallel under the same conditions, and the relative standard deviation was 3.8%; after using MC-MIM / GCE 20 times continuously, it can still maintain more than 90.1% of the initial response, indicating that MC-MIM / GCE has good stability and can be reused.

[0056] Actual sample analysis: The prepared MC-MIM / GCE was used to measure three tap water sample solutions with MC added five times in parallel under the optimal conditions, and the standard working curve of Example 5 was used. ∆i=1.723logc+9.078(R 2 =0.9983) to calculate the amount of MC added. The calculation results show that the relative standard deviation of the results measured by the electrochemical detection method established in this experiment is within 3.9%, and the spike recovery rate is between 93.7% and 104.3%.

[0057] The above experiments prove that the MC-MIM / GCE prepared by the present invention is reliable for detecting the concentration of MC in tap water.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a methcathinone imprinted electrochemical sensor, characterized in that: The following steps are involved: Preparation of methcathinone imprinting prepolymer solution: dissolving functional monomer o-phenylenediamine in an acidic buffer solution and ultrasonically dissolving the solution, then adding methcathinone solution and continuing ultrasonication to obtain methcathinone imprinting prepolymer solution; Preparation of methcathinone imprinted polymer membrane: vertically suspending the three-electrode system and placing it in a methcathinone imprinted prepolymer solution for polymerization to obtain a methcathinone imprinted polymer membrane; Preparation of methcathinone imprinted electrochemical sensor: placing a three-electrode system covered with methcathinone imprinted polymer film in a hydrochloric acid eluent for stirring elution at an elution voltage of -0.1 to -0.3 V to obtain a methcathinone imprinted electrochemical sensor.

2. The method for preparing the methcathinone imprinted electrochemical sensor according to claim 1, characterized in that: The feeding ratio of o-phenylenediamine and acidic buffer solution is 0.10mmol:5mL; The addition ratio of the methcathinone solution to o-phenylenediamine is 50-70 μL: 0.01mmol, wherein the concentration of the methcathinone solution is 0.25mol·L -1 .

3. The method for preparing the methcathinone imprinted electrochemical sensor according to claim 1, characterized in that: The acidic buffer is a HAc-NaAc buffer with a pH of 5-5.

6.

4. The method for preparing the methcathinone imprinted electrochemical sensor according to claim 1, characterized in that: The three-electrode system is composed of a glassy carbon electrode as a working electrode, an Ag / AgCl electrode as a reference electrode, and a Pt wire electrode as an auxiliary electrode; Before use, the glassy carbon electrode is polished by mixing aluminum oxide powder of different particle sizes and deionized water until the redox peak difference of the glassy carbon electrode in K3[Fe(CN)6] solution is within 100mV.

5. The method for preparing the methcathinone imprinted electrochemical sensor according to any one of claims 1 to 3, characterized in that: The number of polymerization cycles is 20-40.

6. The method for preparing the methcathinone imprinted electrochemical sensor according to any one of claims 1 to 3, characterized in that: The hydrochloric acid eluent is 0.6 mol·L -1 HCl solution; The elution time is 10-30min.

7. A methcathinone imprinted electrochemical sensor, characterized in that: The method is prepared by any one of claims 1 to 5.

8. A method for detecting methcathinone, characterized in that: The methcathinone imprinted electrochemical sensor prepared by the method described in any one of claims 2 to 6 is used for detection.

9. The method for detecting methcathinone according to claim 8, characterized in that: The detection method The following steps are involved: Different concentrations of methcathinone solutions were prepared and measured using differential pulse voltammetry to obtain a DPV curve. The response current of DPV was linearly fitted to the concentration of methcathinone to obtain the methcathinone standard curve; Using potassium ferrocyanide as a probe and the methcathinone imprinted electrochemical sensor to detect a sample containing methcathinone, and obtaining a sample response peak change current of methcathinone; The content of methcathinone was calculated based on the sample response peak change current of methcathinone and the methcathinone standard curve.

10. The method for detecting methcathinone according to claim 8, characterized in that: In the process of using the methcathinone imprinted electrochemical sensor to detect a sample containing methcathinone, the sample containing methcathinone is added to a potassium ferrocyanide solution and a methcathinone imprinted electrochemical sensor for incubation and then detected, and the incubation time is 4-6 minutes.

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