CN109828017B - Clematin molecular imprinting electrochemical sensor and preparation method thereof - Google Patents
Clematin molecular imprinting electrochemical sensor and preparation method thereof Download PDFInfo
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Abstract
The invention relates to the field of electrochemical sensors, and provides a preparation method of a simetryn molecular imprinting electrochemical sensor, which comprises the steps of mixing simetryn, methacrylic acid and acetonitrile, and then carrying out prepolymerization reaction to obtain a prepolymerization solution; and mixing the pre-polymerization solution, a cross-linking agent and an initiator, deoxidizing, coating the deoxidizing solution on the surface of an electrode, carrying out thermal polymerization, and washing the molecules of a stripper plate to obtain the simetryn molecularly imprinted electrochemical sensor. The invention combines the molecular imprinting technology with the electroanalytical chemistry detection technology to prepare the simetryn imprinted film on the surface of the electrode, and the method has simple steps and is easy to carry out. The invention also provides a simetryn molecular imprinting electrochemical sensor which is simple in structure, can be used for measuring the content of simetryn, is high in sensitivity, high in accuracy and short in detection time, and overcomes the defects of complex steps, expensive equipment and long time consumption of the traditional analysis method.
Description
Technical Field
The invention relates to the technical field of electrochemical sensors, in particular to a simetryn molecular imprinting electrochemical sensor and a preparation method thereof.
Background
Simetryn is a triazine selective herbicide developed in 1959 by Geigy, switzerland. Due to the characteristics of high efficiency and low toxicity, the compound is widely used after being developed. However, researches show that triazine herbicide residues in the environment and agricultural products can cause various cancers, congenital defects and reproductive tumors, influence normal hormone functions and embryonic development and seriously damage human health. Moreover, the compound has a rigid structure similar to a benzene ring, can stably exist in the environment and crops for a long time, and causes serious harm to human bodies and the environment.
The molecular imprinting technique refers to a process of preparing a polymer having a specific selectivity for a specific substance using the substance as a template. The polymer has multiple sites of action cavities matching the spatial configuration of the template molecule, and is selectively recognized when they meet the template molecule again. In recent years, the technology is researched and applied to trace residue analysis of triazine herbicide pesticide. However, for qualitative and quantitative analysis of simetryn, instruments such as high performance liquid chromatography and chromatography-mass spectrometry are still needed. These instruments are expensive, expensive and time consuming to detect.
Disclosure of Invention
In view of the above, the present invention aims to provide a simetryn molecular imprinting electrochemical sensor and a preparation method thereof. The simetryn molecular imprinting electrochemical sensor provided by the invention is simple in structure and high in sensitivity, can meet the detection requirement of trace simetryn pesticide residues, and does not need expensive instruments such as a high performance liquid chromatography and the like during detection.
In order to achieve the above object, the present invention provides the following technical solutions:
a preparation method of a simetryn molecular imprinting electrochemical sensor comprises the following steps:
(1) mixing template molecules, methacrylic acid and acetonitrile, and then carrying out prepolymerization reaction to obtain a prepolymerization solution; the template molecule is simetryn;
(2) mixing the pre-polymerization liquid, a cross-linking agent and an initiator, and then deoxidizing to obtain an oxygen removal liquid;
(3) and coating the deoxygenation liquid on the surface of an electrode, performing thermal polymerization, and eluting template molecules to obtain the simetryn molecularly imprinted electrochemical sensor.
Preferably, the molar ratio of the template molecule to the methacrylic acid is 1: 3-1: 6.3.
Preferably, the temperature of the prepolymerization reaction is-5 ℃ and the time is 12 h.
Preferably, the cross-linking agent comprises one or more of ethylene glycol dimethacrylate, maleic rosin ethylene glycol acrylate and trimethylolpropane trimethacrylate; the molar ratio of the simetryn to the cross-linking agent is 1: 8.1-1: 18.9.
Preferably, the initiator is azobisisobutyronitrile; the mass of the initiator is 1-3% of the total mass of the methacrylic acid and the cross-linking agent.
Preferably, the oxygen removal is N2Deoxidizing; and the time for deoxidizing is 5-10 min.
Preferably, the coating is specifically: dripping the oxygen removing liquid on the surface of the electrode for 2-6 times; the total coating amount of the oxygen removing liquid is 10-20 mu L.
Preferably, the coating further comprises: carrying out graphene modification on the electrode; the graphene modification is as follows: and dripping graphene dispersion liquid on the surface of the electrode and drying.
Preferably, the thermal polymerization temperature is 50-60 ℃, the vacuum degree is 0.04-0.06 Mpa, and the time is 4-10 h.
Preferably, the eluent for elution is acidified methanol solution; the acidified methanol solution is a mixed solution of methanol and acetic acid; the volume ratio of methanol to acetic acid in the acidified methanol solution is 6: 1-12: 1.
The invention provides a simetryn molecular imprinting electrochemical sensor prepared by the preparation method in the scheme, which comprises an electrode and a simetryn molecular imprinting film arranged on the surface of the electrode.
The invention provides a preparation method of a simetryn molecular imprinting electrochemical sensor, which comprises the following steps: (1) mixing template molecules, methacrylic acid and acetonitrile, and then carrying out prepolymerization reaction to obtain a prepolymerization solution; the template molecule is simetryn; (2) mixing the pre-polymerization liquid, a cross-linking agent and an initiator, and then deoxidizing to obtain an oxygen removal liquid; (3) and coating the deoxygenation liquid on the surface of an electrode, performing thermal polymerization, and eluting template molecules to obtain the simetryn molecularly imprinted electrochemical sensor. The invention combines a molecular imprinting technology with an electroanalytical chemistry detection technology, prepares the simetryn molecular imprinting film on the surface of an electrode by a thermal polymerization method, and obtains the simetryn molecular imprinting electrochemical sensor; the preparation method provided by the invention has simple steps and is easy to carry out.
The invention provides the simetryn molecular imprinting electrochemical sensor prepared by the method in the scheme, the sensor is simple in structure, can be applied to electrochemical detection for determining the content of simetryn, and is high in sensitivity and accuracy. The results of the examples show that the sensor provided by the invention can complete the response within 10min, and the detection limit is as low as 0.89 mu mol/L.
Drawings
FIG. 1 is a cyclic voltammogram of the bare electrode, the blotting electrode before elution, the blotting electrode after elution, and the blotting electrode after adsorption in example 1;
fig. 2 is a linear fit curve of simetryn concentration and sensor peak current value.
Detailed Description
The invention provides a preparation method of a simetryn molecular imprinting electrochemical sensor, which comprises the following steps:
(1) mixing template molecules, methacrylic acid and acetonitrile, and then carrying out prepolymerization reaction to obtain a prepolymerization solution; the template molecule is simetryn;
(2) mixing the pre-polymerization liquid, a cross-linking agent and an initiator, and then deoxidizing to obtain an oxygen removal liquid;
(3) and coating the deoxygenation liquid on the surface of an electrode, performing thermal polymerization, and eluting template molecules to obtain the simetryn molecularly imprinted electrochemical sensor.
The preparation method comprises the steps of mixing template molecules, methacrylic acid and acetonitrile, and then carrying out prepolymerization reaction to obtain a prepolymerization solution. In the present invention, the template molecule is simetryn; the methacrylic acid is a functional monomer, and the acetonitrile is a reaction solvent; the mol ratio of the template molecules to the methacrylic acid is preferably 1: 3-1: 6.3, and more preferably 1: 4-1: 5; the preferable dosage ratio of the template molecule to the acetonitrile is 12-14 mg: 10-20 mL, more preferably 12-14 mg: 15 mL.
In the invention, the mixing is preferably ultrasonic mixing, and the ultrasonic mixing time is preferably 10-15 min; the temperature of the prepolymerization is preferably-5 ℃, more preferably-3 ℃, and the time of the prepolymerization is preferably 12 h; the invention preferably carries out the prepolymerization reaction under the condition of keeping out of the sun; according to the invention, preferably, after the ultrasonic mixing is finished, the mixed solution is placed in a constant temperature refrigerator for a prepolymerization reaction, and the time of the prepolymerization reaction is calculated when the temperature reaches the requirement. The temperature of the prepolymerization is controlled within the range of the invention, which is beneficial to the polymerization of the template molecules and the functional monomers.
After the prepolymerization reaction is finished, the method provided by the invention mixes the prepolymerization solution, the cross-linking agent and the initiator and then carries out deoxygenation to obtain the deoxygenation solution. In the invention, the cross-linking agent preferably comprises one or more of ethylene glycol dimethacrylate, maleic rosin ethylene glycol acrylate and trimethylolpropane trimethacrylate, and more preferably ethylene glycol dimethacrylate; the mol ratio of the simetryn to the cross-linking agent is preferably 1: 8.1-18.9, and more preferably 1: 10-15; the initiator is preferably azobisisobutyronitrile; the mass of the initiator is preferably 1-3%, more preferably 2-2.5% of the total mass of the methacrylic acid and the cross-linking agent.
In the present invention, the oxygen scavenging is preferably N-channel2Deoxidizing; the time for deoxidizing is preferably 5-10 min, and more preferably 6-8 min. The invention reduces the interference of oxygen to the next polymerization reaction by removing the oxygen in the oxygen liquid.
After deoxygenation is finished, the deoxygenation solution is coated on the surface of an electrode and then is subjected to thermal polymerization, and then template molecules are eluted, so that the simetryn molecular imprinting electrochemical sensor is obtained. In the present invention, the electrode is preferably a glassy carbon electrode or a gold electrode; the invention preferably performs pretreatment on the electrode before coating, wherein the pretreatment comprises polishing, ethanol washing and ultrapure water washing which are sequentially performed, and the method for polishing, ethanol washing and ultrapure water washing has no special requirement and can be performed by using a method well known by the technical personnel in the field; the invention removes impurities on the surface of the electrode by pretreatment, and prevents the polymerization of interfering molecular imprinting.
In the present invention, the coating is particularly preferably: dripping the oxygen removing liquid on the surface of the electrode for 2-6 times, and preferably dripping the oxygen removing liquid on the surface of the electrode for 4-5 times; the volume of the deoxygenation liquid is preferably the same in each dripping, standing is carried out for 1-2 min after each dripping, next dripping is carried out after the polymer solution is stable, and standing is preferably carried out for 15min after the last dripping is finished, so that the deoxygenation liquid is stable and then thermal polymerization is carried out; the total coating amount of the oxygen removing liquid is preferably 10-20 mu L, and more preferably 15 mu L; the wet film thickness of the coating obtained after coating is preferably 0.02-0.06 mm, and more preferably 0.032-0.042 mm.
In the present invention, the coating preferably further comprises: carrying out graphene modification on the electrode; the graphene modification specifically comprises: and dripping graphene dispersion liquid on the surface of the electrode and drying. In the invention, the concentration of the graphene dispersion liquid is preferably 4-6 mg/L, more preferably 5mg/L, and the dispersion solvent of the graphene dispersion liquid is preferably N, N-Dimethylformamide (DMF); the dropping amount of the graphene dispersion liquid is preferably 10 mu L; the drying temperature is preferably 50-70 ℃, and more preferably 60 ℃; the drying is preferably carried out in a vacuum drying oven. The invention modifies the electrode with graphene, which can enhance the signal, enlarge the detection range of the sensor for the content of simetryn, and improve the detection sensitivity of the sensor for simetryn.
In the invention, the temperature of the thermal polymerization is preferably 50-60 ℃, more preferably 55 ℃, the vacuum degree is preferably 0.04-0.06 MPa, more preferably 0.05MPa, and the time is preferably 4-10 h, more preferably 5-8 h; in the invention, the electrode coated with the oxygen removing liquid is preferably placed in a vacuum drying oven for thermal polymerization. In the thermal polymerization process, the compound of the functional monomer and the template molecule simetryn is subjected to polymerization reaction with azobisisobutyronitrile and ethylene glycol dimethacrylate; after the thermal polymerization is finished, a layer of uniform and transparent polymer film is formed on the surface of the electrode.
After the polymerization reaction is finished, the invention elutes the template molecules in the polymer film to obtain the simetryn molecularly imprinted electrochemical sensor. In the present invention, the eluent for elution is preferably an acidified methanol solution; the acidified methanol solution is preferably a mixed solution of methanol and acetic acid; the volume ratio of methanol to acetic acid in the acidified methanol solution is preferably 6: 1-12: 1, and more preferably 8: 1-10: 1; the method preferably elutes until the simetryn molecules can not be detected in the eluent, and then uses ultrapure water to wash off the residual eluent on the surface of the electrode. According to the invention, the simetryn molecules are eluted from the polymer through elution, and a three-dimensional hole matched with the size, shape, structure and the like of the template molecules is formed in the polymer, so that the imprinted membrane on the surface of the electrode can specifically identify and combine the template molecules.
The invention provides a simetryn molecular imprinting electrochemical sensor prepared by the method in the scheme, which comprises an electrode and a simetryn molecular imprinting film arranged on the surface of the electrode; the sensor provided by the invention has a simple structure, can specifically recognize and combine the simetryn molecules, has high sensitivity, and can meet the detection requirement of trace simetryn pesticide residues.
In the invention, the electrochemical activity of the simetryn is low, when the sensor disclosed by the invention is used for detecting the simetryn, potassium ferricyanide is preferably used as an ion probe for electrochemical detection, the potassium ferricyanide can generate an oxidation-reduction reaction on the surface of an electrode so as to generate an electrochemical signal, and when the concentration of the simetryn is increased, molecular holes of the simetryn in a molecularly imprinted membrane can be filled up to different degrees to block electron transfer, so that the electrochemical signal can be changed, and the purpose of detecting the content of the simetryn is further achieved.
In the present invention, the simetryn molecularly imprinted electrochemical sensor is preferably applied by the following method:
adding the simetryn solution to be detected into the scanning base solution to obtain a mixed solution; the scanning base solution comprises potassium ferricyanide and lithium chloride;
standing the simetryn molecular imprinting electrochemical sensor in the mixed solution, then performing cyclic voltammetry scanning, and calculating the concentration of the simetryn solution to be detected according to the peak current value and the working curve;
the working curve is a relation curve of a peak current value and the simetryn concentration.
In the invention, the concentration of potassium ferricyanide in the scanning base solution is preferably 5mmol/L, and the concentration of lithium chloride is preferably 1 mmol/L; the time for the standing is preferably 10 min.
In the invention, the linear range of the working curve is 2-30 mu mol/L, and the peak current value of the sensor and the simetryn concentration have a good linear relation in the range. The method for drawing the working curve has no special requirement, and the method known by the person skilled in the art can be used.
The embodiments of the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Treatment of glassy carbon electrodes
Polishing glassy carbon electrode on deer skin with 1.0 μm and 0.5 μm alumina powder, then placing into anhydrous alcohol for ultrasonic treatment for 10min, and finally cleaning with ultrapure water for ultrasonic treatment for 5 min.
Preparation of dicumetryn molecular imprinting electrochemical sensor
(1) Adding 14mg of template molecule simetryn and 0.025mlL functional monomer methacrylic acid into 10mL of acetonitrile solvent in sequence, carrying out ultrasonic treatment for 12min, placing in a constant-temperature refrigerator at 3 ℃, and carrying out prepolymerization for 12 h.
(2) 0.1mL of crosslinking agent ethylene glycol dimethacrylate and 7mg of initiator azobisisobutyronitrile are added into the solution after the prepolymerization is finished, and N is introduced2And deoxidizing for 5min to obtain the deoxidizing liquid.
(3) And (3) coating 13 mu L of the oxygen removing liquid obtained in the step (2) on the surface of a treated clean and smooth glassy carbon electrode for 4 times, placing the electrode for 15min, placing the coated electrode in a vacuum drying box at 60 ℃ for thermal polymerization for 6 h, forming a layer of uniform and transparent polymer film on the surface of the electrode, placing the electrode with the polymer film in an acetic acid-methanol solution (the volume ratio of acetic acid to methanol is 1:9), eluting template molecules until the template molecules cannot be detected in an eluent, washing off the methanol and the acetic acid on the surface of the imprinted electrode by using ultrapure water, and storing the simetryn molecular imprinted electrochemical sensor (the imprinted electrode for short) in the ultrapure water for later use.
Electrochemical detection
(1) Adding a scanning base solution into an electrolytic cell, wherein the concentration of potassium ferricyanide in the scanning base solution is 5mmol/L, the concentration of lithium chloride is 1mmol/L, respectively carrying out cyclic voltammetry scanning on a bare electrode, a blotting electrode before elution, a blotting electrode after elution and a blotting electrode after adsorbing for 10min in the scanning base solution by using a zahner electrochemical workstation, and obtaining results as shown in figure 1, wherein in figure 1, a is a cyclic voltammetry curve of the bare electrode, b is a cyclic voltammetry curve of the blotting electrode before elution, c is a cyclic voltammetry curve of the blotting electrode after elution, and d is a cyclic voltammetry curve of the blotting electrode after adsorption.
As can be seen from FIG. 1, compared with the bare electrode, the oxidation reduction peak is hardly observed on the surface of the imprinted electrode before elution, which indicates that the polymerized simetryn polymer film has a dense film structure and prevents K from being generated3Fe[(CN)6]The redox reaction of the probe between the base solution and the electrode surface; when the template simetryn is eluted, a special identification hole K of simetryn is formed in the polymer film3Fe[(CN)6]Can diffuse to the surface of the glassy carbon electrode through the imprinting holes, so that the peak current is increased; when the imprinted membrane electrode adsorbs simetryn again, the identification holes are occupied again, the mass transfer channel is closed, the redox current intensity is gradually weakened, and the peak current is reduced.
(2) Drawing of working curves
Respectively placing the imprinted electrodes prepared in the second step into 0.5-60 mu mol/L simetryn water solution for adsorption for 10min, and then carrying out cyclic voltammetry scanning in scanning base solution, wherein the concentration of potassium ferricyanide in the scanning base solution is 5mmol/L, and the concentration of lithium chloride in the scanning base solution is 1 mmol/L; and recording peak current values corresponding to different concentrations of the simetryn solution, and then performing linear fitting on the peak current values and the concentrations of the simetryn.
The concentration of the simetryn solution and the corresponding peak current value are shown in table 1;
TABLE 1 concentration of simetryn solution and its peak current value
Performing linear fitting on the peak current value and the simetryn concentration according to the data in table 1 to obtain a fitted curve as shown in fig. 2, wherein the obtained linear regression equation is shown in formula (a), the correlation coefficient R is 0.997, and the detection limit (S/N is 3) is 0.89 μmol/L;
i (μ a) ═ 0.75234c (μmol/L) +35.51797 formula (a).
According to the graph 2, the concentration of the simetryn and the peak current are in a good linear relation within the concentration range of 2-30 mu mol/L, and the lowest detection limit reaches 0.89 mu mol/L, which shows that the sensor prepared by the embodiment has high sensitivity and can meet the detection requirement of trace simetryn pesticide residues.
(3) Determination of recovery rate of simetryn in water
Preparing a 1mmol/L simetryn water solution, dropwise adding the solution into 100mL of scanning base solution (the concentration of potassium ferricyanide in the scanning base solution is 5mmol/L, and the concentration of lithium chloride is 1mmol/L), placing the imprinted electrode in the scanning base solution, standing for 10min, performing cyclic voltammetry scanning, calculating a concentration value according to a working curve shown in formula (a), and calculating the recovery rate, wherein the results are shown in Table 2.
TABLE 2 recovery of simetryn
According to table 2, the concentration of simetryn is detected by using the electrochemical sensor for molecularly imprinting simetryn prepared in the embodiment, the recovery rate is 98.53-99.65%, and the sensor provided by the invention has high accuracy.
Example 2
Treatment of glassy carbon electrodes
Polishing glassy carbon electrode on deer skin with 1.0 μm and 0.5 μm alumina powder, then placing into anhydrous alcohol for ultrasonic treatment for 10min, and finally cleaning with ultrapure water for ultrasonic treatment for 5 min.
Preparation of dicumetryn molecular imprinting electrochemical sensor
(1) 13mg of template molecule simetryn and 0.025mL of functional monomer methacrylic acid are sequentially added into 10mL of acetonitrile solvent, ultrasonic treatment is carried out for 12min, and the mixture is placed in a constant-temperature refrigerator at 3 ℃ for prepolymerization for 12 h.
(2) 0.1mL of crosslinking agent ethylene glycol dimethacrylate and 7mg of initiator azobisisobutyronitrile are added into the solution after the prepolymerization is finished, and N is introduced2And deoxidizing for 5min to obtain the deoxidizing liquid.
(3) And (3) coating 13 mu L of the oxygen removing liquid obtained in the step (2) on the surface of a treated clean and smooth glassy carbon electrode for 4 times, placing the treated electrode in a vacuum drying box at 60 ℃ for thermal polymerization for 6 hours after placing for 15 minutes, forming a layer of uniform and transparent polymer film on the surface of the electrode, then placing the polymerized electrode in an acetic acid methanol solution (the volume ratio of acetic acid to methanol is 1:9), eluting template molecules until the template molecules cannot be detected in an eluent, washing off the methanol and the acetic acid on the surface of the imprinted electrode by using ultrapure water, and then storing the imprinted electrode in the ultrapure water for later use.
Third, determination of recovery rate of simetryn in water
A1 mmol/L simetryn aqueous solution is prepared, the solution is dripped into 100ml scanning base solution (the concentration of potassium ferricyanide in the scanning base solution is 5mmol/L, the concentration of lithium chloride is 1mmol/L), the imprinted electrode is placed in the scanning base solution and stands for 10min, cyclic voltammetry scanning is carried out, a concentration value is calculated according to the working curve in example 1, and the recovery rate is calculated, and the results are shown in Table 3.
TABLE 3 recovery of simetryn
According to table 3, the recovery rate of the simetryn molecular imprinting electrochemical sensor prepared in the embodiment for detecting the concentration of the simetryn is 91.7-101.4%, which shows that the sensor provided by the invention has high accuracy.
Example 3
Treatment of glassy carbon electrodes
Polishing glassy carbon electrode on deer skin with 1.0 μm and 0.5 μm alumina powder, then placing into anhydrous alcohol for ultrasonic treatment for 10min, and finally cleaning with ultrapure water for ultrasonic treatment for 5 min.
Preparation of dicumetryn molecular imprinting electrochemical sensor
(1) Adding 14mg of template molecule simetryn and 0.025mL of functional monomer methacrylic acid into 10mL of acetonitrile solvent in sequence, carrying out ultrasonic treatment for 12min, placing in a constant-temperature refrigerator at-2 ℃, and carrying out prepolymerization for 12 h.
(2) 0.1mL of crosslinking agent ethylene glycol dimethacrylate and 7mg of initiator azobisisobutyronitrile are added into the solution after the prepolymerization is finished, and N is introduced2And deoxidizing for 5min to obtain the deoxidizing liquid.
(3) And (3) coating 13 mu L of the oxygen removing liquid obtained in the step (2) on the surface of a treated clean and smooth glassy carbon electrode for 4 times, placing the treated electrode in a vacuum drying box at 60 ℃ for thermal polymerization for 6 hours after placing for 15 minutes, forming a layer of uniform and transparent polymer film on the surface of the electrode, then placing the polymerized electrode in an acetic acid methanol solution (the volume ratio of acetic acid to methanol is 1:9), eluting template molecules until the template molecules cannot be detected in an eluent, washing off the methanol and the acetic acid on the surface of the imprinted electrode by using ultrapure water, and then storing the imprinted electrode in the ultrapure water for later use.
Third, determination of recovery rate of simetryn in water
A1 mmol/L simetryn aqueous solution is prepared, the solution is dripped into 100mL of scanning base solution (the concentration of potassium ferricyanide in the scanning base solution is 5mmol/L, the concentration of lithium chloride is 1mmol/L), the imprinted electrode is placed in the scanning base solution and stands for 10min, cyclic voltammetry scanning is carried out, a concentration value is calculated according to the working curve in example 1, and the recovery rate is calculated, and the results are shown in Table 4.
TABLE 4 recovery of simetryn
According to table 4, the recovery rate of the simetryn molecular imprinting electrochemical sensor prepared in the embodiment for detecting the concentration of the simetryn is 99.2-102.57%, which indicates that the sensor provided by the invention has high accuracy.
Example 4
Treatment of glassy carbon electrodes
Polishing glassy carbon electrode on deer skin with 1.0 μm and 0.5 μm alumina powder, then placing into anhydrous alcohol for ultrasonic treatment for 10min, and finally cleaning with ultrapure water for ultrasonic treatment for 5 min.
And (3) preparing 5mg/L graphene dispersion liquid by using N, N-Dimethylformamide (DMF) as a solvent. And dripping 10 mu L of graphene dispersion liquid on the surface of the electrode which is polished, then placing the electrode in a vacuum drying box at 60 ℃ for drying, and placing the electrode in ultrapure water for later use.
Preparation of dicumetryn molecular imprinting electrochemical sensor
(1) Adding 14mg of template molecule simetryn and 0.025mlL functional monomer methacrylic acid into 10mL of acetonitrile solvent in sequence, carrying out ultrasonic treatment for 12min, placing in a constant-temperature refrigerator at 3 ℃, and carrying out prepolymerization for 12 h.
(2) 0.1mL of crosslinking agent ethylene glycol dimethacrylate and 7mg of initiator azobisisobutyronitrile are added into the solution after the prepolymerization is finished, and N is introduced2And deoxidizing for 5min to obtain the deoxidizing liquid.
(3) And (3) coating 13 mu L of the oxygen removing liquid in the step (3) on the surface of a graphene-modified glassy carbon electrode for 4 times, placing the coated electrode in a vacuum drying box at 60 ℃ for thermal polymerization for 6 hours after placing for 15 minutes, forming a layer of uniform and transparent polymer film on the surface of the electrode, then placing the polymerized electrode in an acetic acid methanol solution (the volume ratio of acetic acid to methanol is 1:9), eluting template molecules until the template molecules cannot be detected in an eluent, washing off the methanol and the acetic acid on the surface of the imprinted electrode by using ultrapure water, and then storing the imprinted electrode in the ultrapure water for later use.
Third, comparison of peak current values of imprinted electrodes
Placing a bare electrode modified by graphene, a imprinted electrode modified by graphene before elution and an imprinted electrode modified by graphene after elution in a scanning base solution for cyclic voltammetry scanning, and simultaneously placing the bare electrode without modified by graphene, the imprinted electrode without modified by graphene before elution in the embodiment 1 and the imprinted electrode without modified by graphene after elution in the scanning base solution for cyclic voltammetry scanning; the concentration of potassium ferricyanide in the scanning base solution is 5mmol/L, and the concentration of lithium chloride is 1 mmol/L. The scanning results are shown in table 5:
table 5 cyclic voltammetry scan results of graphene modified imprinted electrodes
| Peak current value of bare electrode | Peak current value before elution | Peak current value after elution | |
| Graphene modified imprinted electrode | 225.9μA | 2.29μA | 96.08μA |
| Graphene-free modified imprinted electrode | 65.52μA | 2.19μA | 45.75μA |
As can be seen from table 5, the graphene has the effect of enhancing signals, and compared with an electrode without graphene modification, the detection range of the simetryn content is expanded, and the detection sensitivity of the simetryn is improved.
The embodiment shows that the simetryn molecular imprinting electrochemical sensor provided by the invention is simple in structure, high in sensitivity and accuracy when used for detecting simetryn, short in detection time and capable of overcoming the defects of complex steps, expensive equipment and long time consumption of the traditional method.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (1)
1. A preparation method of a simetryn molecular imprinting electrochemical sensor is characterized by comprising the following steps:
firstly, processing a glassy carbon electrode:
polishing a glassy carbon electrode on a deer skin by using alumina powder with the particle size of 1.0 micron and alumina powder with the particle size of 0.5 micron in sequence, then putting the polished electrode into absolute ethyl alcohol for ultrasonic treatment for 10min, and finally cleaning the polished electrode by using ultrapure water for ultrasonic treatment for 5 min;
secondly, preparing the simetryn molecular imprinting electrochemical sensor:
(1) adding 14mg of template molecule simetryn and 0.025mL of functional monomer methacrylic acid into 10mL of acetonitrile solvent in sequence, carrying out ultrasonic treatment for 12min, placing in a constant-temperature refrigerator at 3 ℃, and carrying out prepolymerization for 12 h;
(2) 0.1mL of crosslinking agent ethylene glycol dimethacrylate and 7mg of initiator azobisisobutyronitrile are added into the solution after the prepolymerization is finished, and N is introduced2Deoxidizing for 5min to obtain a deoxidizing liquid;
(3) and (3) coating 13 mu L of the oxygen removing liquid obtained in the step (2) on the surface of a treated clean and smooth glassy carbon electrode for 4 times, placing the treated electrode for 15min, placing the coated electrode in a vacuum drying box at 60 ℃ for thermal polymerization for 6 hours to form a uniform and transparent polymer film on the surface of the electrode, and then placing the electrode with the polymer film in a volume ratio of 1:9, eluting the template molecules in the acetic acid methanol solution until the template molecules cannot be detected in the eluent, and then washing off methanol and acetic acid on the surface of the imprinting electrode by using ultrapure water to obtain the simetryn molecular imprinting electrochemical sensor.
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