A weakly conductive amino acid molecular imprinted polymer film electrochemical sensor and preparation method thereof, and a method for detecting ketamine

Abstract

The present invention provides a weakly conductive amino acid molecular imprinting polymer film electrochemical sensor and a preparation method thereof, and a ketamine detection method, belonging to the technical field of drug detection. The present invention uses amino acids as functional monomers and ketamine (KT) as template molecules to synthesize weakly conductive amino acids @KT-MIPs by electropolymerization. Due to the rich active sites and good electrochemical activity of amino acids, the polyamino acid film polymerized on the electrode surface exhibits excellent catalytic activity and biocompatibility. The polyamino acid film not only combines ketamine as a template molecule, but also improves the electrocatalytic performance of the ketamine detection electrode, and has specific recognition of ketamine, which can improve the accuracy of the detection results.

Description

Technical Field

[0001] The present invention relates to the technical field of drug detection, and in particular to a weakly conductive amino acid molecular imprinting polymer film electrochemical sensor and a preparation method thereof, and a ketamine detection method. Background Art

[0002] Traditionally, analytical methods for ketamine detection include gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, capillary electrophoresis, and immunoassay. These techniques offer excellent specificity and sensitivity; however, high cost, laborious measurements, and poor portability make them unsuitable for on-site analysis. On the other hand, electrochemical sensors have the advantages of high sensitivity, good selectivity, and real-time detection and analysis. Therefore, electrochemical detection of ketamine holds great promise.

[0003] However, most of the methods reported so far are based on indirect determination using potassium ferrocyanide as a probe, which increases the uncertainty of detection. In addition, complex actual samples, such as hair, blood, body fluids, drugs and other interfering substances, will greatly affect indirect determination. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a weakly conductive amino acid molecular imprinted polymer film electrochemical sensor and a preparation method thereof, and a method for detecting ketamine. The weakly conductive amino acid molecular imprinted polymer film electrochemical sensor prepared by the present invention can be used to directly detect ketamine with good detection accuracy.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a weakly conductive amino acid molecular imprinted polymer film electrochemical sensor, comprising the following steps:

[0007] mixing the amino acid, ketamine and buffer solution to obtain a mixed solution;

[0008] Using a glassy carbon electrode to electropolymerize the mixed solution to obtain an electropolymerized film;

[0009] The ketamine in the electropolymer film is removed to obtain the weakly conductive amino acid molecular imprinting polymer film electrochemical sensor.

[0010] Preferably, the amino acids include one or more of L-cysteine, tyrosine, histidine and lysine.

[0011] Preferably, the mass ratio of ketamine to amino acid is 1:1-5.

[0012] Preferably, the buffer solution is a phosphate buffer solution, and the pH value of the phosphate buffer solution is 7.

[0013] Preferably, the electropolymerization is performed by cyclic voltammetry, and the scan rate of the cyclic voltammetry is 100 mV·s -1 , the potential relative to Ag / AgCl is -1.5 to +2.2 V, and the number of cycles is 8 to 20 times.

[0014] Preferably, the removal is elution by static immersion, and the elution solution is a methanol-acetic acid mixture, and the volume ratio of methanol to acetic acid in the methanol-acetic acid mixture is 1-3:9-30.

[0015] The present invention also provides an amino acid molecular imprinting polymer film electrochemical sensor with weak conductivity prepared by the preparation method described in the above technical solution.

[0016] The present invention also provides a method for detecting ketamine, comprising the following steps:

[0017] Mixing the phosphate buffer solution and the ketamine-containing solution to obtain a test solution;

[0018] The weakly conductive amino acid molecular imprinted polymer film electrochemical sensor described in the above technical solution is used to perform square wave voltammetry on the test solution.

[0019] Preferably, the potential measured by the square wave voltammetry is 0.6-1.3 V, the amplitude is 0.025 V, and the frequency is 15 Hz.

[0020] Preferably, the concentration of ketamine in the test solution is 5.0×10 -7 ~2.0×10 -5 mol / L.

[0021] The present invention provides a method for preparing a weakly conductive amino acid molecular imprinted polymer membrane electrochemical sensor, comprising the following steps: mixing amino acids, ketamine and a buffer solution to obtain a mixed solution; electropolymerizing the mixed solution using a glassy carbon electrode to obtain an electropolymer membrane; and removing ketamine from the electropolymer membrane to obtain the weakly conductive amino acid molecular imprinted polymer membrane electrochemical sensor.

[0022] The present invention uses amino acids as functional monomers and ketamine (KT) as a template molecule to synthesize weakly conductive amino acid@KT-MIPs through electropolymerization. Due to the rich active sites and good electrochemical activity of amino acids, the polyamino acid film polymerized on the electrode surface exhibits excellent catalytic activity and biocompatibility. The polyamino acid film not only combines ketamine as a template, but also improves the electrocatalytic performance of the ketamine detection electrode, and has specific recognition of ketamine, which can improve the accuracy of the detection results.

[0023] The preparation method of the present invention has simple and reliable process, integrated design, short detection cycle, and is suitable for on-site rapid detection.

[0024] The present invention also provides a weakly conductive amino acid molecular imprinted polymer membrane electrochemical sensor prepared by the preparation method described in the above technical solution. The molecular imprinted polymer membrane electrochemical sensor of the present invention is an electrochemical sensor based on a weakly conductive polyamino acid molecular imprinted membrane, has excellent detection sensitivity, and detects ketamine using square wave voltammetry (SWV) with a detection range of 1×10 -12 ~4×10 -4 mol·L -1 , the detection limit is 8.0×10 -13 It can be used to directly detect ketamine, can directly detect the oxidation peak of KT, and can be used for the determination of ketamine in actual hair samples and urine samples, with high detection sensitivity, strong anti-interference ability and wide linear range. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 SEM images of poly-L-Cys-KT-MIM / GCE before and after elution of the template;

[0026] Figure 2 Cyclic voltammetry curves CVs of different modified electrodes;

[0027] Figure 3 The SWV detection response current of bare electrode, imprinted membrane electrode before and after template elution, and non-imprinted electrode to KT;

[0028] Figure 4 is the detection response current of different amino acid imprinted membranes to KT;

[0029] Figure 5 is the detection response current of KT with different electropolymerization cycles;

[0030] Figure 6 Square wave voltammetric peak current-concentration curves and standard curves of different concentrations of KT on the modified electrode;

[0031] Figure 7 The structural diagram and HRMS diagram of the electrochemical oxidation product. DETAILED DESCRIPTION

[0032] The present invention provides a method for preparing a weakly conductive amino acid molecular imprinted polymer film electrochemical sensor, comprising the following steps:

[0033] mixing the amino acid, ketamine and buffer solution to obtain a mixed solution;

[0034] Using a glassy carbon electrode to electropolymerize the mixed solution to obtain an electropolymerized film;

[0035] The ketamine in the electropolymer film is removed to obtain the weakly conductive amino acid molecular imprinting polymer film electrochemical sensor.

[0036] In the present invention, unless otherwise specified, the raw materials used are all commercially available products in the art.

[0037] The present invention mixes amino acids, ketamine and a buffer solution to obtain a mixed solution.

[0038] In the present invention, the amino acid preferably includes one or more of L-cysteine ​​(L-Cys), tyrosine, histidine and lysine.

[0039] In the present invention, the mass ratio of ketamine to amino acid is preferably 1:1-5, more preferably 1:2-4, most preferably 1:3, and the ketamine serves as a template molecule.

[0040] In the present invention, the buffer solution is preferably a phosphate buffer solution, and the pH value of the phosphate buffer solution is preferably 7.

[0041] In the present invention, the concentration of the phosphate buffer solution is preferably 0.1 mol·L -1 .

[0042] In the present invention, the mixing is preferably ultrasonic, and the ultrasonic time is preferably 10 to 30 minutes. During the mixing process, the amino acid and ketamine interact with each other to form intermolecular hydrogen bonds.

[0043] After obtaining the mixed solution, the present invention uses a glassy carbon electrode (GCE) to electropolymerize the mixed solution to obtain an electropolymerized film.

[0044] In the present invention, the electropolymerization is preferably performed by cyclic voltammetry, and the scan rate of the cyclic voltammetry is preferably 100 mV·s -1 The potential relative to Ag / AgCl is preferably -1.5 to +2.2 V, and the number of cycles is preferably 8 to 20 times. The number of cycles can ensure the thickness of the electropolymer film, avoiding the problem of the imprinting sites being buried and difficult to elute due to being too thick, and also avoiding the problem of the polymer film being unable to completely cover the electrode surface and having few imprinting sites due to being too thin.

[0045] In the present invention, the temperature of the electropolymerization is preferably room temperature, and the time is preferably 10 to 30 minutes.

[0046] In the present invention, the glassy carbon electrode is preferably cleaned before use. The present invention has no particular limitation on the specific method of the cleaning process, and the method familiar to those skilled in the art may be used.

[0047] After obtaining the electropolymerized membrane, the present invention removes ketamine from the electropolymerized membrane to obtain the molecular imprinted polymerized membrane electrochemical sensor (poly-amino acid-KT-MIM / GCE).

[0048] In the present invention, the removal is preferably elution, preferably by static immersion, the elution solution is preferably a methanol-acetic acid mixture, and the volume ratio of methanol to acetic acid in the methanol-acetic acid mixture is preferably 1-3:9-30.

[0049] The present invention also provides a molecular imprinting polymer membrane electrochemical sensor prepared by the preparation method described in the above technical solution.

[0050] The present invention also provides a method for detecting ketamine, comprising the following steps:

[0051] Mixing the phosphate buffer solution and the ketamine-containing solution to obtain a test solution;

[0052] The molecularly imprinted polymer film electrochemical sensor described in the above technical solution is used to perform square wave voltammetry on the test solution.

[0053] The present invention mixes a phosphate buffer solution with a ketamine-containing solution to obtain a test solution.

[0054] In the present invention, the ketamine-containing solution is preferably a solution obtained after treatment of a hair sample and a urine sample.

[0055] In the present invention, the solution after the hair sample is treated is preferably prepared by a method comprising the following steps: washing the hair sample with water and acetone, drying, cutting the obtained sample into small pieces of 1 mm, and then grinding it into powder in a freezing grinder, dispersing 20 mg of the obtained hair powder in 1.0 mL of methanol, and then ultrasonicating it in an ice bath for 30 minutes, taking the supernatant after centrifugation, evaporating it naturally, and dissolving the evaporated residue in 100 μL of methanol to obtain the solution after the hair sample is treated.

[0056] In the present invention, the pH value of the phosphate buffer solution is preferably 9.

[0057] In the present invention, the concentration of the phosphate buffer solution is preferably 0.1 mol·L -1 .

[0058] In the present invention, the concentration of ketamine in the test solution is preferably 5.0×10 -7 ~2.0×10 -5 mol / L.

[0059] After obtaining the liquid to be tested, the present invention uses the molecular imprinted polymer film electrochemical sensor described in the above technical solution to perform square wave voltammetry on the liquid to be tested.

[0060] In the present invention, the potential measured by the square wave voltammetry is preferably 0.6 to 1.3 V, the amplitude is preferably 0.025 V, and the frequency is preferably 15 Hz.

[0061] In the present invention, the square wave voltammetry determination preferably uses the molecular imprinted polymer film electrochemical sensor as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum column electrode as the counter electrode.

[0062] In the present invention, the molecular imprinted polymer film electrochemical sensor exhibits the strongest response to KT at +0.95V, and has a sensitizing effect on the determination of KT.

[0063] After the square wave voltammetry determination is completed, the present invention preferably further comprises detecting the concentration of ketamine in the ketamine-containing solution. The present invention preferably calculates the concentration of ketamine in the ketamine-containing solution using a predetermined standard equation, wherein the standard equation uses the concentration of ketamine as the horizontal coordinate and the response current as the vertical coordinate.

[0064] In the present invention, the standard equation is preferably prepared by a method comprising the following steps: using poly-L-Cys-KT-MIM / GCE to continuously measure ketamine KT solutions of different solubility (0.5μM, 1μM, 2μM, 3μM, 5μM, 7μM, 10μM, 12μM, 14μM, 16μM, 20μM,) in 0.1M phosphate buffer (pH 9), and square wave voltammetry SWV response under the conditions of a scanning range of 0.6-1.3V, a balance time of 5s, and a frequency of 15Hz.

[0065] In the present invention, the linear range of the peak current change I of the standard equation and the KT concentration is preferably 5.0×10 -7 ~2.0×10 -5 mol·L -1 The equation is I = 1.08746 + 0.28239C (μmol·L -1 )(R 2 =0.9830).

[0066] The present invention preferably further comprises identifying the oxidation product of the ketamine in the electrochemical process. The present invention preferably identifies the oxidation product by high resolution mass spectrometry (HRMS), confirms the oxidation peak of the ketamine by cyclic voltammetry, and places the molecularly imprinted polymer film electrochemical sensor in 5 mL, 0.1 mol·L -1 PBS (pH 9) and 1.0 mmol·L -1The current was measured in KT solution and scanned at a potential of 1.1 V (vs. Ag / AgCl) for 4 to 10 hours. KT was completely oxidized on the electrode surface. The KT solution was extracted with dichloromethane. After the dichloromethane was completely evaporated, the solid was dissolved in chromatographic grade methanol to obtain a HRMS standard solution sample, which was stored at 4°C in the dark. The sample was used for HRMS detection, and the conditions of the HRMS detection were as follows: the chromatographic column was a C18 column (100 mm×2.1 mm, 1.9 μm), the temperature was 27.5°C, the mobile phase was 0.1 wt% formic acid and ultrapure water (A)-methanol (B), isokinetic elution (A / B=2 / 98, v / v), the flow rate was 0.3 mL / min, the injection volume was 1 μL, and it worked in high-resolution Fourier transform mass spectrometer mode with a resolution of 60,000, an ionization temperature of 230°C, a spray voltage of 3.5 kV, and a positive polarity HESI (vacuum insulated heatable electrospray ion source) mode.

[0067] In order to further illustrate the present invention, the molecular imprinted polymer film electrochemical sensor and its preparation method, and the detection method of ketamine provided by the present invention are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present invention.

[0068] Example 1

[0069] The electrochemical detection method of ketamine comprises the following steps:

[0070] 1. Preparation of poly-L-Cys-KT-MIM / GCE modified electrode: First, KT and L-Cys were mixed in a 1:1 mass ratio in 10 mL and 0.1 mol·L -1 Phosphate buffer solution (PBS, pH 7) was ultrasonicated for 30 min to obtain a mixed solution. The cleaned glassy carbon electrode was placed in the above solution and -1 The scanning rate was 10 times, and the cyclic voltammetry was performed continuously in the potential range of -1.5 to +2.2 V relative to Ag / AgCl. After polymerization, the template molecules were removed by elution with methanol:acetic acid (volume ratio 1:9) solution for 30 minutes to obtain poly-L-Cys-KT-MIM / GCE.

[0071] Under the same conditions, non-imprinted polymer NIM / GCE was synthesized without KT.

[0072] 2. Electrochemical determination of ketamine: The poly-L-Cys-KT-MIM / GCE modified electrode was used as the working electrode, the Ag / AgCl electrode was used as the reference electrode, and the platinum column electrode was used as the counter electrode. Cyclic voltammetry was used to measure different electrodes in 5 mM and 10 mL potassium ferrocyanide solutions (containing 0.1 M KCl). The scan rate was 100 mV / s and the scan range was -0.2 to 0.6 V.

[0073] Scanning electron microscopy (SEM) experiments were performed on the morphology of poly-L-Cys-KT-MIM / GCE before and after elution of the template molecule. The obtained SEM photos are shown in Figure 1 shown. Figure 1 A is before elution, B is after elution. Figure 1 A regular structure of poly-L-Cys-KT-MIM / GCE can be observed in both images, indicating that the poly-L-Cys layer was successfully deposited on the electrode surface. However, the surface morphology before and after template elution was obviously different. Figure 1 A shows that the membrane before elution is smooth, uniform and dense, with more white crystals scattered on the surface. Figure 1 In B), a relatively rough surface was observed and the white crystals were significantly reduced, indicating that most of the template molecules KT had been successfully removed by the elution step.

[0074] Figure 2 Cyclic voltammetry curves a of a bare glassy carbon electrode in 5 mM and 10 mL potassium ferrocyanide solutions (containing 0.1 M KCl) are shown respectively; cyclic voltammetry curves b and c of a poly-L-Cys imprinted membrane before and after removal of KT; Figure 2 Figure d and e are cyclic voltammetry curves of the non-imprinted electrode before and after elution in B. A pair of typical redox peaks with the largest peak current appeared in the bare GCE (curve a). In the case of the poly-L-Cys-KT-MIM modified electrode, the ferrocyanide redox peak disappeared (curve b), indicating that the surface of the GCE was covered by a weakly conductive dense polymer film. However, after removing KT from the poly-L-Cys imprinted membrane, a pair of redox peaks reappeared (curve c), indicating that the imprinted sites were generated after the template molecules were eluted, which made [Fe(CN)6] 3- / 4- It is easier to contact the electrode surface and promote electron transfer. For non-imprinted electrodes ( Figure 2 In B), the peak current does not change much before (curve d) and after (curve e) the template molecule is eluted, indicating that the elution step does not damage the poly-L-Cys membrane.

[0075] Figure 3The peak current responses of bare glassy carbon electrode, poly-L-Cys / MIM / GCE before and after elution, and non-imprinted electrode to 10 μM ketamine in 0.1M phosphate buffer solution with a pH of 9 are shown respectively, with a scanning range of 0.6-1.3V, a balance time of 5s, and a frequency of 15Hz. It can be seen that the response of bare GCE to KT is almost unobservable (curve a). However, poly-L-Cys-KT-MIM / GCE shows the strongest response to KT at +0.95V (curve c), and the peak current is twice that before elution (curve b). This peak is an irreversible oxidation peak, corresponding to the oxidation of secondary amines. In the case of non-imprinted electrode (curve d), a weak oxidation peak can be observed due to the influence of cysteine. It shows that the molecular imprinting membrane is conducive to the accumulation of KT on the electrode surface, making the poly-L-cysteine ​​membrane have a sensitizing effect on the determination of KT.

[0076] Example 2

[0077] The technical solution in Example 1 was further optimized, common amino acids lysine, arginine and L-cysteine ​​were compared and studied, and different amino acids were used to prepare molecularly imprinted polymer film electrochemical sensors, which differed from Example 1 only in the types of amino acids. The effects of different types of amino acids on imprinting and detecting KT were studied.

[0078] The current responses of the electrodes modified with different polyamino acid films were determined by square wave voltammetry measurements (scan range 0.6-1.3 V, equilibrium time 5 s, frequency 15 Hz) in 0.1 M phosphate buffer (pH 9) containing 10 μM ketamine. Figure 4 As shown, L-cysteine ​​was the most sensitive to the KT response current compared with arginine and lysine, which was attributed to the more active sites and the role of the sulfhydryl group of L-Cys.

[0079] Example 3

[0080] Further optimizing the technical solution in Example 1, changing the number of electropolymerization cycles in Example 1, optimizing the number of electropolymerization cycles of the poly-L-Cys modified electrode, the number of polymerization cycles is 5 to 25, and the current response obtained is as follows Figure 5 As shown, it can be seen that when the number of polymerization turns is less than 10, the peak current increases with the increase of the number of polymerization turns, and after exceeding 10 turns, the peak current decreases with the increase of the number of polymerization turns, so the optimal number of polymerization turns is 10.

[0081] Example 4

[0082] To verify the detection performance of the present invention for ketamine, poly-L-Cys-KT-MIM / GCE was used to continuously measure ketamine KT solutions of different solubility (0.5μM, 1μM, 2μM, 3μM, 5μM, 7μM, 10μM, 12μM, 14μM, 16μM, 20μM) in 0.1M phosphate buffer (pH 9), and the square wave voltammetry SWV response and calibration curve were obtained under the conditions of scanning range of 0.6-1.3V, equilibrium time of 5s, and frequency of 15Hz. Figure 6 As shown in Figure A, the peak current increases with the increase of KT concentration. The linear range of the peak current change I and KT concentration is 5.0×10 -7 ~2.0×10 -5 mol·L -1 The equation is I = 1.08746 + 0.28239C (μmol·L -1 )(R 2 =0.9830), the standard curve is Figure 6 As shown in B. The detection limit (LOD) is 3S b / m Calculated to be 1.6×10 -7 mol·L -1 , where Sb is the standard deviation of the blank amount, and m is the slope of the calibration curve. It can be seen that the method of the present invention shows a relatively low LOD and a satisfactory dynamic range.

[0083] Example 5

[0084] Identification of oxidation products by high resolution mass spectrometry (HRMS). Figure 7 All oxidation products identified using HRMS and the corresponding structures are provided. Figure 7 A in the middle is a high-resolution mass spectrometry detection image. Figure 7 B is a schematic diagram of the oxidation products. It shows that there are three main products (K1 to K3) after oxidation: the first oxidation product K1 (m / z 224.0843, C 12 H 15 ClNO) eluted after 0.85 min. K1 is norketamine, which is the product of the demethylation reaction after the oxidation of the secondary amine. The second product K2 (m / z 254.0945, C 13 H 17 ClNO2) eluted after 0.97 minutes and was the hydroxylation of ketamine. The third product K3 (m / z 236.0843, C 13 H 15 ClNO) eluted after 1.02 min, probably due to the formation of double bonds in the structure.

[0085] HRMS conditions: The chromatographic column is a C18 column (100mm×2.1mm, 1.9μm), the temperature is 27.5℃, the mobile phase is 0.1wt% formic acid and ultrapure water (A)-methanol (B), isocratic elution (A / B=2 / 98, v / v). The flow rate is 0.3mL / min, and the injection volume is 1μL. The instrument works in high-resolution Fourier transform mass spectrometer mode with a resolution of 60000. The specific conditions are: ionization temperature 230℃, spray voltage 3.5kV, and positive polarity HESI (heatable electrospray ion source with vacuum insulation protection) mode.

[0086] To verify the reliability of the test structure, the prepared electrode was used for the determination of ketamine in human urine and hair samples (suspicious persons) by the standard addition method. Specifically, the prepared electrode was used to add sample solutions containing different amounts of ketamine (see Table 1) in 0.1M phosphate buffer (pH 9) (the solution was the ketamine standard solution added to the treated urine and hair sample solutions), and the SWV technique was used to determine the respective oxidation peak currents. Then, the current values ​​were brought into the linear relationship in Example 4 to obtain the corresponding concentrations, and then compared with the actual added amounts. The results are shown in Table 1. It can be seen that the RSD values ​​of the determination results of ketamine in urine and hair samples were within 4.0%, and the spike recovery rates were between 92 and 102.4%, which preliminarily indicated that the determination results were accurate and reliable. The hair sample solution was prepared as follows: the hair sample was washed with water and acetone, dried, cut into 1 mm segments, and then ground into powder in a freezer grinder. 20 mg of the obtained hair powder was dispersed in 1.0 mL of methanol, and then ultrasonicated in an ice bath for 30 minutes. After centrifugation, the supernatant was taken and naturally evaporated. The evaporated residue was dissolved in 100 μL of methanol.

[0087] Table 1 Test results of different test samples

[0088]

[0089] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a weakly conductive amino acid molecular imprinted polymer film electrochemical sensor, characterized in that: The following steps are involved: Mixing an amino acid, ketamine and a buffer solution to obtain a mixed solution; the amino acid is L-cysteine; The mixed solution is electropolymerized by using a glassy carbon electrode to obtain an electropolymerized film; the electropolymerization is performed by cyclic voltammetry, and the scanning rate of the cyclic voltammetry is 100 mV·s -1 , the potential relative to Ag / AgCl is -1.5 to +2.2 V, and the number of cycles is 8 to 20 times; The ketamine in the electropolymer film is removed to obtain the amino acid molecular imprinting polymer film electrochemical sensor with weak conductivity.

2. The preparation method according to claim 1, characterized in that: The mass ratio of ketamine to amino acid is 1:1-5.

3. The preparation method according to claim 1, characterized in that: The buffer solution is a phosphate buffer solution, and the pH value of the phosphate buffer solution is 7.

4. The preparation method according to claim 1, characterized in that: The removal is elution, which is carried out by static immersion. The elution liquid is a methanol-acetic acid mixture, and the volume ratio of methanol to acetic acid in the methanol-acetic acid mixture is 1-3:9-30.

5. A weakly conductive amino acid molecular imprinted polymer film electrochemical sensor prepared by the preparation method according to any one of claims 1 to 4.

6. A method for detecting ketamine, characterized in that: The following steps are involved: Mixing the phosphate buffer solution and the ketamine-containing solution to obtain a test solution; The test solution is subjected to square wave voltammetry determination using the weakly conductive amino acid molecular imprinted polymer film electrochemical sensor described in claim 5.

7. The detection method according to claim 6, characterized in that: The potential measured by the square wave voltammetry method is 0.6-1.3 V, the amplitude is 0.025 V, and the frequency is 15 Hz.

8. The detection method according to claim 6, characterized in that: The concentration of ketamine in the test solution is 5.0×10 -7 ~2.0×10 -5 mol / L.

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