CN106841343A - A kind of Tebuconazole molecular engram film electrode, portable sensor and its application method and application - Google Patents

Abstract

The invention provides a tebuconazole molecularly imprinted membrane electrode, comprising a base electrode, sequentially modifying gold nanoparticles, mercapto graphene and gold-Prussian blue on the surface of the base electrode, and gold-Prussian blue attached to the surface of the gold-Prussian blue Tebuconazole molecularly imprinted membrane; the tebuconazole molecularly imprinted membrane is an o-aminophenol and resorcinol polymer with tebuconazole as a template molecule. The tebuconazole molecularly imprinted membrane electrode provided by the invention is used for quantitative detection of tebuconazole, and the detection limit can reach 1.63× ^10-8 mol/L, and the sensitivity is high. The invention immobilizes the probe molecule Prussian blue on the tebuconazole molecularly imprinted membrane electrode, can realize the direct measurement of the non-electroactive target compound in the sample, makes the operation of the sensor more convenient and is suitable for on-site rapid detection.

Description

A tebuconazole molecularly imprinted membrane electrode, a portable sensor and its use method and application

technical field

The invention relates to the technical field of pesticide detection, in particular to a tebuconazole molecularly imprinted membrane electrode, a portable sensor, and a use method and application thereof.

Background technique

Tebuconazole is a high-efficiency triazole fungicide, which is widely used in the disease control of peanuts, barley, rice, apples and other crops. Frequent use will cause soil pollution and endanger the ecosystem, groundwater and human health.

At present, the method for detecting tebuconazole is mainly chromatographic technology, which has the advantages of high sensitivity, good accuracy, and excellent qualitative and quantitative analysis. However, the limitations of these analysis methods are: the required analytical instruments are generally placed in standard analytical laboratories far away from the site, and the instruments are expensive, complicated to operate, and require the operation of professionals; sample pretreatment takes a long time, and it is difficult to meet the requirements of pesticide residues in agricultural products. The demand for on-site rapid detection.

In the prior art, although the electrochemical sensor is convenient to carry, the quantitative detection sensitivity of pesticide residues is low, and the electrochemical sensor needs an electronic medium as a probe to indicate the strength of the electrochemical signal, and these probes will pollute the sample and affect the detection result. Interference is generated, resulting in inaccurate test results. Therefore, there is an urgent need to develop a rapid detection method for pesticide residues that is easy to carry, low in price and high in detection accuracy.

Contents of the invention

In view of this, the purpose of the present invention is to provide a device that can be applied to the quantitative determination of tebuconazole, which is easy to carry and has high accuracy and sensitivity.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides a tebuconazole molecularly imprinted membrane electrode, comprising a base electrode, sequentially modifying gold nanoparticles, mercapto graphene and gold-Prussian blue on the surface of the base electrode, and the gold-Prussian blue attached to the surface of the gold-Prussian blue Tebuconazole molecularly imprinted membrane;

The tebuconazole molecularly imprinted membrane is an o-aminophenol and resorcinol polymer with tebuconazole as a template molecule.

The present invention provides a method for preparing a tebuconazole molecularly imprinted membrane electrode described in the above technical solution, comprising the following steps:

(1) placing the substrate electrode in a tetrachloroalloy acid solution, performing electrodeposition by a constant potential method, depositing gold nanoparticles on the surface of the substrate electrode, and obtaining a gold nanoparticle modified electrode;

(2) The gold nanoparticle modified electrode obtained in the step (1) is left standing in the aqueous solution of mercaptographene, so that the mercaptographene is modified on the gold nanoparticle surface of the electrode to obtain the mercaptographene-gold nanoparticle modification electrode;

(3) The mercaptographene-gold nanoparticle modified electrode obtained in the step (2) is placed in a mixed solution containing potassium nitrate, tetrachloroalloy acid and potassium ferrocyanide, and gold-nanoparticles are deposited by cyclic voltammetry. Prussian blue particles to obtain a gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode;

(4) placing the gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode obtained in the step (3) in a phosphate buffer containing tebuconazole, o-aminophenol and resorcinol for electropolymerization, Obtain a polymer film modified electrode;

(5) placing the polymer membrane modified electrode in the step (4) in a mixed solution of methanol and acetic acid to remove tebuconazole molecules in the polymer membrane to obtain a tebuconazole molecularly imprinted membrane electrode.

Preferably, the concentration of the tetrachloroalloy acid solution in step (1) is 2.5-3.5 mmol/L, and the electrodeposition time is 80-150 s.

Preferably, the concentration of the graphene-mercapto aqueous solution in step (2) is 0.25-0.5 mg/mL, and the standing time is 2-6 hours.

Preferably, the concentration of potassium nitrate in the mixed solution described in step (3) is 0.05～0.2mol/L, the concentration of tetrachloroalloy acid is 0.5～1.5mmol/L and the concentration of potassium ferrocyanide is 0.5～1.5mmol/L L; the conditions of cyclic voltammetry are: the potential range is 0-1.0V, the scan rate is 50mV/s, and the scan is 15-30 cycles.

Preferably, in the phosphoric acid mixed solution described in step (4), the concentrations of o-aminophenol and resorcinol are independently 2.0 to 2.5 mmol/L, and the concentration of tebuconazole is 0.5 to 1 mmol/L. The concentration is 0.01-0.07mmol/L; the electropolymerization conditions are: the potential range is -0.4-1.0V, the scanning rate is 50mV/s, and the scanning is 8-10 circles.

Preferably, in the mixed solution of methanol and acetic acid described in step (5), the volume ratio of methanol and acetic acid is 1:7˜1:11.

The present invention also provides a portable sensor for the quantitative determination of tebuconazole, including a working electrode, a counter electrode, a reference electrode and an electrolyte solution, and the working electrode is the tebuconazole molecularly imprinted membrane electrode or For the tebuconazole molecularly imprinted membrane electrode obtained by the preparation method described in the above technical solution, the electrolyte solution is a potassium nitrate solution with a pH value of 5.0-8.0 and a concentration of 0.08-0.14 mol/L.

The present invention provides the application of the tebuconazole molecularly imprinted membrane electrode described in the above technical solution or the portable sensor described in the above technical solution in the determination of tebuconazole pesticide residues in agricultural products.

Preferably, the method for the determination of tebuconazole pesticide residues in agricultural products comprises the following steps:

1) Suspend the tebuconazole molecularly imprinted membrane electrode in the sample solution, and absorb for 10-20 minutes;

2) Use the tebuconazole molecularly imprinted membrane electrode adsorbed in the step (1) as a working electrode, form a three-electrode system with a counter electrode and a reference electrode, perform an electrochemical test in an electrolyte solution, and record the differential obtained from the test. Pulse voltammetry scanning curve and maximum response current value;

3) obtain the content of tebuconazole in the sample solution according to the maximum response current value of the sample solution obtained by the standard curve and the step (2);

The standard curve is a linear curve between the maximum response current value of the differential pulse voltammetry test and the concentration of tebuconazole.

Compared with the prior art, the present invention has the following advantages:

The tebuconazole molecularly imprinted membrane electrode provided by the present invention effectively improves the tebuconazole detection efficiency by sequentially modifying gold nanoparticles, mercapto graphene and gold-Prussian blue on the base electrode, and then combining the tebuconazole molecularly imprinted membrane. Sensitivity and Accuracy. The tebuconazole molecularly imprinted membrane electrode provided by the present invention is used for detection, and the detection limit can reach 1.63×10 ^{- 8} mol/L. It can be seen that the tebuconazole molecularly imprinted membrane electrode provided by the present invention has high sensitivity and can be used for tebuconazole quantitative detection.

In the tebuconazole molecularly imprinted membrane electrode provided by the present invention, a layer of gold nanoparticles is first deposited on the surface of the substrate electrode, and then the gold nanoparticles are connected to the mercaptographene through a stable gold-sulfur bond by using the gold-philic ability of the sulfur atom to modify the mercapto group. Graphene can expand the specific surface area of the electrode, amplify the response signal of the sensor, and then significantly improve the sensitivity of the electrode.

The tebuconazole molecularly imprinted membrane electrode provided by the present invention co-deposits gold-Prussian blue on the surface of mercapto graphene, so that the probe molecule Prussian blue is fixed on the electrode, and it is not necessary to add probe molecules to the electrolyte during detection, simplifying the Experimental operation, improve the sensitivity and accuracy of direct determination. The tebuconazole molecularly imprinted membrane electrode provided by the invention is especially suitable for on-site rapid detection, making the on-site detection of pesticide residues in agricultural products more rapid and accurate.

The present invention co-deposits gold-Prussian blue on the surface of the mercapto graphene-gold nanoparticle modified electrode, which can also improve the conductivity of the electrode, further improve the detection sensitivity of the electrode, and shorten the detection time. Combined with the tebuconazole molecularly imprinted membrane composed of tebuconazole as a template molecule and resorcinol and o-aminophenol as polymerized functional monomers, it can specifically recognize the tebuconazole molecule, so that the obtained tebuconazole molecularly imprinted membrane The membrane electrode has good sensitivity and specificity, and can accurately and efficiently identify tebuconazole molecules. Tests have shown that the tebuconazole molecularly imprinted membrane provided by the present invention has a low response value to structural analogs such as triaconazole and penconazole, and can effectively distinguish tebuconazole from other pesticides with similar structures, and avoid pesticides with similar structures to tebuconazole influence on the measurement results.

The portable sensor for the quantitative determination of tebuconazole provided by the present invention includes the above-mentioned tebuconazole molecularly imprinted membrane electrode as a working electrode, a counter electrode, a reference electrode and an electrolyte solution, compared with the existing chromatography or chromatography-mass spectrometry As far as the detection method is concerned, the detection instrument is small in size, easy to carry out, not limited by the detection location, and can be used for on-site detection. Moreover, the portable sensor provided by the invention takes 15.5 to 17.5 minutes to quantitatively measure the tebuconazole content in the sample, which greatly shortens the detection time and improves the detection efficiency of the tebuconazole.

When the portable sensor provided by the invention is used for quantitative determination of tebuconazole in agricultural products, the recovery rate of tebuconazole can reach 77.9% to 118.69%, which shows that the portable sensor provided by the invention has high quantitative determination accuracy and can meet the requirements of pesticides in agricultural products. Requirements for on-site testing of residues.

The portable sensor for the quantitative determination of tebuconazole provided by the present invention has the advantages of simple structure, small volume, and easy operation. Compared with the chromatograph and other instruments used in the existing chromatographic detection method, the cost is low, easy to operate and carry out, and is especially suitable for on-site Quick check.

Description of drawings

Figure 1 is a schematic diagram of the preparation process of tebuconazole molecularly imprinted membrane electrode;

Among them, AuNPs is gold nanoparticles, SH-G is mercaptographene, Au-PB is gold-Prussian blue, Teb is tebuconazole molecule, analogue is tebuconazole molecular analog, p(AP-DHB) is tebuconazole Alcohol molecularly imprinted membrane;

Figure 2 is the cyclic voltammogram of electropolymerization gold-Prussian blue-mercaptographene-gold nanoparticles modified electrode process; the illustration is the cyclic voltammogram obtained after removing Prussian blue from the electrode of electropolymerization gold-Prussian blue;

Fig. 3 is the cyclic voltammogram of electropolymerization polymer membrane electrode process;

Figure 4 is the cyclic voltammogram of tebuconazole molecularly imprinted membrane electrode modification and detection process;

Figure 5 is the differential pulse voltammetry scanning curve of the tebuconazole portable sensor measuring different concentrations of tebuconazole samples; the inset is the standard curve of the logarithm value-current response change value of the sample measured by the sensor composed of different modified working electrodes;

Fig. 6 is a selectivity evaluation diagram of tebuconazole and its structural analogues.

detailed description

The invention provides a tebuconazole molecularly imprinted membrane electrode, comprising a base electrode, sequentially modifying gold nanoparticles, mercapto graphene and gold-Prussian blue on the surface of the base electrode, and the gold-Prussian blue attached to the surface of the gold-Prussian blue Tebuconazole molecularly imprinted membrane;

The tebuconazole molecularly imprinted membrane is an o-aminophenol and resorcinol polymer with tebuconazole as a template molecule.

The present invention has no limitation on the type of the substrate electrode, and commercially available electrodes can be used, such as platinum electrodes, gold electrodes, glassy carbon electrodes, carbon fiber microelectrodes or chemically modified electrodes, preferably glassy carbon electrodes.

In the present invention, the specific surface area of the base electrode can be increased after the gold nanoparticles are modified, thereby increasing the passing current intensity, thereby improving the detection sensitivity of the electrode. At the same time, gold nanoparticles can also be combined with mercaptographene through covalent bonds, providing a basis for the immobilization of mercaptographene.

In the present invention, the mercapto graphene is graphene modified with mercapto groups. The present invention does not have any limitation on the source of mercaptographene, and commercially available products can be used. In some embodiments of the present invention, mercaptographene sold by Suzhou Carbonfeng Graphene Technology Co., Ltd. is preferably used.

In the present invention, the gold-Prussian blue is to co-precipitate Prussian blue and gold nanoparticles on the surface of mercaptographene, and the Prussian blue in the gold-Prussian blue is used as a probe molecule, and the co-deposition with gold nanoparticles can effectively Ensure that the probe molecules are firmly combined on the electrode, and gold nanoparticles and mercapto graphene can also be firmly combined by forming a covalent gold-sulfur bond; the gold-Prussian blue can further improve the conductivity of the electrode, so that the electrical signal The conduction speed is faster, the measurement time is effectively shortened, and the detection sensitivity of the electrode can also be enhanced.

The present invention provides a method for preparing a tebuconazole molecularly imprinted membrane electrode described in the above technical solution, comprising the following steps:

(1) placing the substrate electrode in a tetrachloroalloy acid solution, performing electrodeposition by a constant potential method, depositing gold nanoparticles on the surface of the substrate electrode, and obtaining a gold nanoparticle modified electrode;

(2) The gold nanoparticle modified electrode obtained in the step (1) is left standing in the aqueous solution of mercaptographene, so that the mercaptographene is modified on the gold nanoparticle surface of the electrode to obtain the mercaptographene-gold nanoparticle modification electrode;

(3) The mercaptographene-gold nanoparticle modified electrode obtained in the step (2) is placed in a mixed solution containing potassium nitrate, tetrachloroalloy acid and potassium ferrocyanide, and gold-nanoparticles are deposited by cyclic voltammetry. Prussian blue particles to obtain a gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode;

(4) placing the gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode obtained in the step (3) in a phosphate buffer containing tebuconazole, o-aminophenol and resorcinol for electropolymerization, Obtain a polymer film modified electrode;

(5) placing the polymer membrane modified electrode in the step (4) in a mixed solution containing methanol and acetic acid to remove tebuconazole molecules in the polymer membrane to obtain a tebuconazole molecularly imprinted membrane electrode.

The preparation steps of the tebuconazole molecularly imprinted membrane electrode of the present invention are shown in FIG. 1 .

In the present invention, before the base electrode is placed in the tetrachloroalloy acid solution, the base electrode is preferably pretreated and cleaned. In the present invention, the method of said pretreatment and cleaning preferably comprises the following steps:

a. Soak the substrate electrode in a mixed solution of hydrogen peroxide and concentrated sulfuric acid for 10-30 minutes, and polish it with 0.03-0.10 μm Al ₂ O ₃ ;

b. Clean the base electrode after grinding and polishing in the step a, and ultrasonicate in water for 8 to 15 minutes;

c. Place the base electrode after ultrasonication in the step b in 0.1-1.0 mol/L dilute sulfuric acid solution, scan by cyclic voltammetry for 15-30 cycles, wash and dry.

In the present invention, the matrix electrode is placed in the mixed solution of hydrogen peroxide and concentrated sulfuric acid for 10-30 minutes. Specifically, in the present invention, the base electrode is soaked in a mixed solution of hydrogen peroxide and concentrated sulfuric acid. In the present invention, the volume ratio of the hydrogen peroxide to concentrated sulfuric acid is 1:2-5, preferably 1:3. The soaking time in the present invention is preferably 15-25 minutes, more preferably 20 minutes. The volume concentration of the hydrogen peroxide in the present invention is preferably 20-50%, more preferably 30%; the concentrated sulfuric acid can be commercially available.

The present invention has no limitation on the volume used when treating the base electrode with the mixed solution of hydrogen peroxide and concentrated sulfuric acid, as long as the base electrode can be immersed. The invention adopts the mixed solution of hydrogen peroxide and concentrated sulfuric acid to treat the substrate electrode, and can effectively remove the organic impurities on the substrate electrode.

In the present invention, the base electrode treated with the mixed solution is ground and polished with 0.03-0.10 μm Al ₂ O ₃ . In the present invention, the particle size of the Al ₂ O ₃ is preferably 0.05 μm. The present invention uses Al ₂ O ₃ to grind and polish until the surface of the electrode reaches the level of a mirror surface and stops grinding and polishing. Grinding and polishing can remove the oxide layer and inert layer on the surface of the base electrode.

After grinding and polishing, the present invention cleans the substrate electrode, and ultrasonics in water for 8-15 minutes. Specifically, in the present invention, the ground and polished base electrode is washed with water to remove residual Al ₂ O ₃ on the surface of the base electrode. In the present invention, the ultrasonic time is preferably 9-12 minutes, more preferably 10 minutes.

After ultrasonication, the present invention places the base electrode in 0.1-1.0 mol/L dilute sulfuric acid solution, uses cyclic voltammetry to scan for 15-30 circles, washes and dries, and obtains the pretreated base electrode. The concentration of the dilute sulfuric acid solution in the present invention is preferably 0.4-0.8 mol/L, more preferably 0.5 mol/L. In the present invention, the voltage range of the cyclic voltammetry is -0.2 to 1.6V; the number of scanning cycles of the cyclic voltammetry is preferably 18 to 25 cycles, more preferably 20 cycles; the scanning cycle of the cyclic voltammetry The speed is preferably 50mV/s.

The invention adopts cyclic voltammetry to scan the substrate electrode to polarize the electrode, and cleans the surface of the substrate electrode by electrochemical means.

In the invention, the base electrode is placed in the tetrachloroalloy acid solution, and a constant potential method is used for electrodeposition to obtain the gold nano particle modified electrode. The concentration of the tetrachloroalloy acid solution in the present invention is preferably 2.5-3.5 mmol/L, more preferably 3 mmol/L. In the present invention, the electrodeposition time is preferably 80-150s, more preferably 100s. The potential during the constant potential deposition of the present invention is -0.3～-0.1V, preferably -0.2V. The present invention adopts the constant potential method to deposit the gold nanoparticles, which is to reduce the gold ions in the tetrachloroalloy acid to the gold nanoparticles by passing an electric current so as to deposit on the surface of the substrate electrode.

After the gold nanoparticle-modified electrode is obtained, the present invention places the gold nanoparticle-modified electrode in an aqueous solution of mercaptographene to obtain a mercaptographene-gold nanoparticle-modified electrode. In the present invention, utilizing the gold-philic ability of the sulfur atom and following the principle of soft-hard acid-base interaction, the mercaptographene and the gold nanoparticles are linked by a polar covalent gold-sulfur bond, so that the mercaptographene is modified on the surface of the gold nanoparticles .

The reaction of the mercapto graphene and the gold nanoparticles in the present invention can be completed at normal temperature. In the present invention, the concentration of the graphene-mercapto aqueous solution is 0.25-0.5 mg/mL, more preferably 0.25 mg/mL. The standing time of the present invention is preferably 2 to 6 hours, more preferably 4 hours.

The invention improves the detection sensitivity of the tebuconazole molecularly imprinted membrane electrode through the double sensitization effect of the gold nanoparticle and the mercapto graphene, lowers the detection limit, and can be used in the actual quantitative detection of the tebuconazole.

After obtaining the mercaptographene-gold nanoparticle modified electrode, the present invention places the mercaptographene-gold nanoparticle modified electrode in a mixed solution containing potassium nitrate, tetrachloroalloy acid and potassium ferrocyanide, and adopts cyclic voltammetry Gold-Prussian blue is deposited on the surface of mercaptographene to obtain a gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode. In the mixed solution of the present invention, the concentration of potassium nitrate is preferably 0.05～0.2mol/L, more preferably 0.1mol/L; the concentration of tetrachloroalloy acid is preferably 0.5～1.5mmol/L, more preferably 1mmol/L ; The concentration of potassium ferrocyanide is preferably 0.5-1.5mmol/L, more preferably 1mmol/L. In the present invention, the conditions of the cyclic voltammetry are preferably: a potential range of 0-1.0V, a scan rate of 50mV/s, and 15-30 scan cycles; the number of scan cycles is more preferably 17 cycles.

In the present invention, following chemical reaction takes place when adopting cyclic voltammetry to deposit gold-Prussian blue:

The tetrachloroalloy acid reaction in the mixed solution generates gold nanoparticles:

HAuCl ₄ →H ⁺ +AuCl ₄ ^-

AuCl ₄ ^- +3e ^- → Au ⁽⁰⁾ +4Cl ^-

Au ⁽⁰⁾ +3HOH→Au(OH) ₃ +3H ⁺

Potassium ferrocyanide in the mixed solution reacts to generate Prussian blue:

[Fe(CN) ₆ ] ^3- +6H ⁺ →Fe ³⁺ +6HCN

Fe ³⁺ +e ^- → Fe ²⁺

Fe ²⁺ +[Fe(CN) ₆ ] ^3- →[Fe ³⁺ Fe ²⁺ (CN) ₆ ] ^-

After generating gold nanoparticles and Prussian blue, they were co-deposited on the surface of mercaptographene under the action of cyclic voltammetry to obtain a gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode.

In the present invention, the obtained gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode is placed in a phosphate buffer solution containing tebuconazole, o-aminophenol and resorcinol for electropolymerization to obtain a polymer membrane modified electrode . The electropolymerization of the present invention is preferably carried out by cyclic voltammetry, and the conditions of the cyclic voltammetry are preferably: potential range -0.4～1.0V, scanning rate is 50mV/s, scanning 8～10 circles; The number of scanning circles is preferably 9 circles.

The concentration of the phosphate buffer of the present invention is preferably 0.01～0.07mmol/L, more preferably 0.05mmol/L; the concentration of tebuconazole in the phosphate buffer is preferably 0.5～1mmol/L, more preferably 0.7mmol /L; the concentration of o-aminophenol and resorcinol in the phosphate buffer solution is preferably independently 2.0～2.5mmol/L, more preferably 2.1mmol/L; the pH of the phosphate buffer solution is preferably 5～ 9, more preferably 7.

In the present invention, the tebuconazole molecule is used as a template, and o-aminophenol and resorcinol are used as polymerized functional monomers to polymerize under electropolymerization into a tebuconazole molecularly imprinted membrane containing template molecules, and the tebuconazole molecule is imprinted. Membrane finish on gold-Prussian blue surface.

In the present invention, the polymer film modified electrode is preferably obtained after standing still for 3-16 hours after electropolymerization. The standing time is more preferably 5h. The present invention does not have any limitation on the standing environment, and it can be left standing in the air. In the present invention, the purpose of resting the electrode with the polymer film after the electropolymerization is to make the polymer film firmly bonded to the surface of the electrode, and prevent the polymer film from being damaged by directly removing template molecules after the electropolymerization.

After obtaining the polymer-modified electrode, the present invention places the polymer-modified electrode in a mixed solution of methanol and acetic acid to remove template molecules in the polymer film to obtain the tebuconazole molecularly imprinted membrane electrode. In the mixed solution of methanol and acetic acid in the present invention, the volume ratio of methanol and acetic acid is preferably 1:7-1:11, more preferably 1:9. In the present invention, the mixed solution is preferably stirred during the process of removing the template molecules in the polymer film, the stirring speed is preferably 100-150 rpm, more preferably 120 rpm; the stirring time is preferably 20-40 min , more preferably 30min. The mixed solution of acetic acid and methanol adsorbs tebuconazole molecules by competing with the polymer membrane, so that the tebuconazole molecules are removed from the polymer membrane, thereby obtaining a molecularly imprinted membrane with hole recognition sites for tebuconazole molecules.

The present invention also provides a portable sensor for the quantitative determination of tebuconazole, including a working electrode, a counter electrode, a reference electrode and an electrolyte solution, and the working electrode is the tebuconazole molecularly imprinted membrane electrode or For the tebuconazole molecularly imprinted membrane electrode obtained by the preparation method described in the above technical solution, the electrolyte solution is a potassium nitrate solution with a pH value of 5.0-8.0 and a concentration of 0.08-0.14 mol/L.

In the present invention, the reference electrode is preferably a calomel electrode, and the counter electrode is preferably a platinum electrode.

In the present invention, the pH value of the electrolyte solution is preferably 7.0; the concentration of the potassium nitrate solution is preferably 0.1 mol/L. In the portable sensor provided by the present invention, since the probe molecule Prussian blue is immobilized on the working electrode tebuconazole molecularly imprinted membrane electrode, the electrolyte solution can be directly used for the determination of the target compound in the sample without adding probe molecules.

The present invention provides the application of the tebuconazole molecularly imprinted membrane electrode described in the above technical solution or the portable sensor described in the above technical solution in the determination of tebuconazole pesticide residues in agricultural products.

Preferably, the method for the determination of tebuconazole pesticide residues in agricultural products comprises the following steps:

1) Suspend the tebuconazole molecularly imprinted membrane electrode in the sample solution, and absorb for 10-20 minutes;

2) Use the tebuconazole molecularly imprinted membrane electrode adsorbed in step 1) as a working electrode, form a three-electrode system with a counter electrode and a reference electrode, perform an electrochemical test in an electrolyte solution, and record the differential pulse obtained from the test Volt-ampere scanning curve and maximum response current value;

3) according to the standard curve and the maximum response current value of the sample solution obtained in step 2), obtain the content of tebuconazole in the sample solution;

The standard curve is a linear curve between the maximum response current value of the differential pulse voltammetry test and the concentration of tebuconazole.

In the present invention, the tebuconazole molecularly imprinted membrane electrode is suspended in the sample solution and adsorbed for 10-20 minutes. The adsorption time of the present invention is preferably 15 minutes. The sample solution of the present invention is obtained by homogenizing the substance to be tested, and preferably the substance to be tested includes vegetables, cucumbers, beans, and radishes. The present invention does not have any limitation on the homogenization method, and conventional homogenization methods in the field can be used, such as manual homogenization, mechanical homogenization, ultrasonic homogenization, and repeated freezing and thawing.

In the present invention, preferably, the tebuconazole molecularly imprinted membrane electrode after adsorption is washed with water and then electrochemically tested.

After the adsorption, the present invention uses the tebuconazole molecularly imprinted membrane electrode as the working electrode, forms a three-electrode system with a counter electrode and a reference electrode, performs an electrochemical test in an electrolyte solution, and records the differential pulse voltammetry scanning curve obtained from the electrochemical test and The maximum response current value. In the present invention, the differential pulse voltammetry conditions are preferably: voltage 0.5-0.1V, pulse width 50ms, time interval 0.5s, step potential 5mV, modulation amplitude 50mV.

Since the probe molecule is immobilized on the working electrode, the current change generated by the reaction between the tebuconazole in the sample and the tebuconazole molecularly imprinted membrane is directly covered by the gold- Prussian blue accepts and then produces electrochemical signal changes, thereby affecting the maximum response current value in the electrochemical test. By calculating the change in the maximum response current value, the content of tebuconazole contained in the sample can be characterized. The present invention calculates and obtains the content of tebuconazole in the sample solution according to the standard curve and the maximum response current value of the sample solution obtained by the electrochemical test. Specifically, in the present invention, the difference between the maximum response current value when not adsorbed and the maximum corresponding current value after adsorption is used as the ordinate, and the logarithm of the tebuconazole concentration is used as the abscissa to draw a standard curve. The preferred linear range of the standard curve of the present invention is 0-0.4mmol/L.

Specifically, the standard curve of the present invention is to select the tebuconazole solution with a concentration of 0, 0.00005, 0.0002, 0.0005, 0.001, 0.006, 0.03, 0.1, 0.2 and 0.4mmol/L, using the tebuconazole in the tebuconazole portable sensor The azole alcohol molecularly imprinted membrane electrode is used to adsorb each standard series of samples, and the maximum response current value is measured by differential pulse voltammetry. The logarithmic value of the concentration of tebuconazole standard series samples is used as the abscissa to draw the standard curve. The conditions of differential pulse voltammetry in the present invention are the same as the conditions for determining the sample to be tested.

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

The glassy carbon electrode was soaked in a mixed solution of 30% hydrogen peroxide and concentrated sulfuric acid with a volume ratio of 1:3 for 20 minutes, polished with 0.05 μm Al ₂ O ₃ until the surface of the electrode was mirror-like, washed with water, and ultrasonicated in water for 10 minutes. Dry the electrode after ultrasonication with nitrogen, place it in 0.5 mol/L dilute sulfuric acid solution, and scan 20 cycles in the voltage range of -0.2 ~ 1.6V by cyclic voltammetry. After scanning, the electrode was washed with water and dried with nitrogen to obtain the pretreated substrate electrode.

Place the pretreated substrate electrode in 3mmol/L tetrachloroalloy acid solution, and use the constant potential method to electrodeposit at a voltage of -0.2V for 100s, so that gold nanoparticles are deposited on the surface of the substrate electrode to obtain a gold nanoparticle modified electrode. .

The gold nanoparticle-modified electrode was placed in a 0.25 mg/mL mercaptographene aqueous solution, and allowed to stand for 4 hours to obtain a mercaptographene-gold nanoparticle-modified electrode.

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and the gold-Prussian blue was deposited by cyclic voltammetry under the conditions of a potential range of 0-1.0V, a scan rate of 50mV/s, and 17 cycles of scanning to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.1mol/L potassium nitrate, 1mmol/L tetrachloroalloy acid and 1mmol/L potassium ferrocyanide.

The gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode was placed in a phosphate buffer solution containing tebuconazole, o-aminophenol and resorcinol, and cyclic voltammetry was used in the potential range of -0.4 to 1.0V, Under the conditions of scanning rate 50mV/s and scanning 9 circles, polymerize into a tebuconazole molecularly imprinted film containing template molecules and modify it on the gold-Prussian blue surface of the electrode. After washing with water, dry it with nitrogen and let it stand for 5 hours to obtain a polymer membrane electrode. The concentration of the phosphate buffer is 0.05mmol/L, and the pH value is 7.0; the concentration of tebuconazole in the phosphate buffer is 0.7mmol/L, and the concentrations of o-aminophenol and resorcinol are both 2.1mmol/L.

The polymer membrane electrode was placed in a mixed solution of methanol and acetic acid with a volume ratio of 1:9 to remove template molecules, stirred at 120 rpm for 30 min, and washed with water to obtain a tebuconazole molecularly imprinted membrane electrode.

The preparation time of the tebuconazole molecularly imprinted membrane electrode is short, the preparation method is simple, the time consumption is less, and the economic benefit is high.

Example 2

The base electrode was placed in 2.5mmol/L tetrachloroalloy acid solution, and the electrodeposition was carried out at -0.1V for 80s by the constant potential method, so that the gold nanoparticles were deposited on the surface of the base electrode, and the gold nanoparticles modified electrode was obtained.

The gold nanoparticle-modified electrode was placed in a 0.25 mg/mL mercaptographene aqueous solution, and allowed to stand for 2 hours to obtain a mercaptographene-gold nanoparticle-modified electrode.

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and gold-Prussian blue was deposited by cyclic voltammetry under the conditions of potential range 0-1.0V, scanning rate 50mV/s, and scanning 15 circles to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.05mol/L potassium nitrate, 0.5mmol/L tetrachloroalloy acid and 0.5mmol/L potassium ferrocyanide.

The gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode was placed in a phosphate buffer solution containing tebuconazole, o-aminophenol and resorcinol, and cyclic voltammetry was used in the potential range of -0.4 to 1.0V, Under the conditions of scanning rate 50mV/s and scanning 8 circles, the tebuconazole molecularly imprinted membrane containing template molecules was polymerized and modified on the gold-Prussian blue surface of the electrode to obtain a polymer membrane electrode. The concentration of the phosphate buffer is 0.01mmol/L, the concentration of tebuconazole in the phosphate buffer is 0.5mmol/L, and the pH value is 5.0; the concentrations of o-aminophenol and resorcinol are both 2.0mmol/L.

The polymer membrane electrode was placed in a mixed solution of methanol and acetic acid with a volume ratio of 1:7 to remove template molecules, stirred at 100 rpm for 20 min, and washed with water to obtain a tebuconazole molecularly imprinted membrane electrode.

Example 3

The glassy carbon electrode was soaked in a mixed solution of 20% hydrogen peroxide and concentrated sulfuric acid with a volume ratio of 1:2 for 15 minutes, polished with 0.05 μm Al ₂ O ₃ until the surface of the electrode was mirror-like, washed with water, and ultrasonicated in water for 8 minutes. Dry the electrode after ultrasonication with nitrogen, place it in 0.4 mol/L dilute sulfuric acid solution, and scan 15 circles in the voltage range of -0.2 ~ 1.6V by cyclic voltammetry. After scanning, the electrode was washed with water and dried with nitrogen to obtain the pretreated substrate electrode.

Place the pretreated substrate electrode in a 3.5mmol/L tetrachloroalloy acid solution, and use the constant potential method to electrodeposit at a voltage of -0.3V for 150s, so that gold nanoparticles are deposited on the surface of the substrate electrode, and gold nanoparticles are modified. electrode.

The gold nanoparticle-modified electrode was placed in a 0.5 mg/mL mercaptographene aqueous solution, and allowed to stand for 6 hours to obtain a mercaptographene-gold nanoparticle-modified electrode.

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and gold-Prussian blue was deposited by cyclic voltammetry under the conditions of potential range 0-1.0V, scanning rate 50mV/s, and scanning 30 circles to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.2mol/L potassium nitrate, 1.5mmol/L tetrachloroalloy acid and 1.5mmol/L potassium ferrocyanide.

The gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode was placed in a phosphate buffer solution containing tebuconazole, o-aminophenol and resorcinol, and cyclic voltammetry was used in the potential range of -0.4 to 1.0V, Under the conditions of scanning rate 50mV/s and scanning 10 circles, polymerize into a tebuconazole molecularly imprinted membrane containing template molecules and modify it on the gold-Prussian blue surface of the electrode. After washing with water, dry it with nitrogen and let it stand for 16 hours to obtain a polymer membrane electrode. The concentration of the phosphate buffer is 0.07mmol/L, and the pH value is 6.0; the concentration of tebuconazole in the phosphate buffer is 1mmol/L, and the concentrations of o-aminophenol and resorcinol are both 2.5mmol/L.

The polymer membrane electrode was placed in a mixed solution of methanol and acetic acid with a volume ratio of 1:11 to remove template molecules, stirred at 150 rpm for 40 min, and washed with water to obtain a tebuconazole molecularly imprinted membrane electrode.

Example 4

The glassy carbon electrode was soaked in a mixed solution of 30% hydrogen peroxide and concentrated sulfuric acid with a volume ratio of 1:3 for 20 minutes, polished with 0.05 μm Al ₂ O ₃ until the surface of the electrode was mirror-like, washed with water, and ultrasonicated in water for 10 minutes. Dry the electrode after ultrasonication with nitrogen, place it in 0.5 mol/L dilute sulfuric acid solution, and scan 20 cycles in the voltage range of -0.2 ~ 1.6V by cyclic voltammetry. After scanning, the electrode was washed with water and dried with nitrogen to obtain the pretreated substrate electrode.

Place the pretreated substrate electrode in 3mmol/L tetrachloroalloy acid solution, and use the constant potential method to electrodeposit at a voltage of -0.2V for 100s, so that gold nanoparticles are deposited on the surface of the substrate electrode to obtain a gold nanoparticle modified electrode. .

The gold nanoparticle-modified electrode was placed in a 0.25 mg/mL mercaptographene aqueous solution, and allowed to stand for 4 hours to obtain a mercaptographene-gold nanoparticle-modified electrode.

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and the gold-Prussian blue was deposited by cyclic voltammetry under the conditions of a potential range of 0-1.0V, a scan rate of 50mV/s, and 17 cycles of scanning to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.1mol/L potassium nitrate, 1mmol/L tetrachloroalloy acid and 1mmol/L potassium ferrocyanide. The cyclic voltammogram of electropolymerized gold-Prussian blue-mercaptographene-gold nanoparticles modified electrode is shown in Figure 2.

It can be seen from Figure 2 that Figure 2 shows the characteristic peaks obtained during cyclic scanning of the gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode for 1 to 17 cycles. The redox peaks that are continuously enhanced by the increase of the peaks are the mutual conversion peaks of Prussian blue and Prussian white, which is a typical feature of the successfully modified electrode of Prussian blue, indicating that the gold-Prussian blue co-deposition method in the preparation method provided by the present invention is adopted Able to fix Prussian blue successfully.

At the same time, in order to verify the gold-Prussian blue modified electrode process, gold particles were also successfully modified on the electrode surface. Put the pretreated glassy carbon electrode in the mixed solution, and use cyclic voltammetry to deposit gold-Prussian blue under the conditions of potential range 0-1.0V, scanning rate 50mV/s, and scanning 17 times to obtain gold-Prussian blue Modified electrodes. The mixed solution is 0.1mol/L potassium nitrate, 1mmol/L tetrachloroalloy acid and 1mmol/L potassium ferrocyanide. The gold-Prussian blue modified electrode was placed in 0.1mol/L sodium hydroxide aqueous solution again to remove the Prussian blue, and the cyclic voltammogram of the electrode after removal was shown in the inset of Figure 2. It can be clearly seen from the illustration in Figure 2 that the Prussian blue redox peak disappears, and the characteristic peaks of gold nanoparticles are clearly visible. It shows that in the present invention, both the Prussian blue and the gold nanoparticles exist independently, and are modified on the surface of the mercapto graphene by co-deposition.

Example 5

The base electrode was placed in a 3 mmol/L tetrachloroalloy acid solution, and was electrodeposited at -0.3V for 100 s by a potentiostatic method, so that gold nanoparticles were deposited on the surface of the base electrode to obtain a gold nanoparticle-modified electrode.

The gold nanoparticle-modified electrode was placed in a 0.25 mg/mL mercaptographene aqueous solution, and allowed to stand for 4 hours to obtain a mercaptographene-gold nanoparticle-modified electrode.

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and the gold-Prussian blue was deposited by cyclic voltammetry under the conditions of a potential range of 0-1.0V, a scan rate of 50mV/s, and 17 cycles of scanning to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.1mol/L potassium nitrate, 1mmol/L tetrachloroalloy acid and 1mmol/L potassium ferrocyanide.

The gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode was placed in a phosphate buffer solution containing tebuconazole, o-aminophenol and resorcinol, and cyclic voltammetry was used in the potential range of -0.4 to 1.0V, Under the conditions of scanning rate 50mV/s and scanning 9 circles, polymerize into a tebuconazole molecularly imprinted film containing template molecules and modify it on the gold-Prussian blue surface of the electrode. After washing with water, dry it with nitrogen and let it stand for 5 hours to obtain a polymer membrane electrode. The concentration of the phosphate buffer is 0.05mmol/L, and the pH value is 7.0; the concentration of tebuconazole in the phosphate buffer is 0.7mmol/L, and the concentrations of o-aminophenol and resorcinol are both 2.1mmol/L. The cyclic voltammogram of the polymer membrane electrode process is shown in Figure 3.

It can be seen from Figure 3 that when electropolymerization is scanned by cyclic voltammetry for 1 to 10 cycles, irreversible oxidation peaks appear at 0.3V and 0.72V in the first cycle, which are irreversible oxidation peaks of o-aminophenol and resorcinol , as the number of scanning cycles increased, the oxidation peak decreased sharply until it approached 0, indicating that the polymer film with tebuconazole molecules successfully aggregated on the electrode surface and hindered the current signal. At the same time, there are Prussian blue peaks at 0.1V and 0.02V, and the Prussian blue peak signal gradually decreases as the electropolymerization progresses, indicating that the formation of a polymer film with tebuconazole molecules hinders the electrochemical signal of Prussian blue, and then During the detection process, the content of tebuconazole molecules can be characterized by the strength of the Prussian blue electrochemical signal.

Example 6

In this experiment, cyclic voltammetry was used to characterize the mercaptographene-gold nanoparticle modified electrode, the gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode, the polymer membrane electrode, the tebuconazole molecularly imprinted membrane electrode and the adsorption 0.1 Tebuconazole molecularly imprinted membrane electrode of mmol/L tebuconazole, obtain the cyclic voltammogram of the modification process and detection of tebuconazole molecularly imprinted membrane electrode.

Preparation of the electrode to be tested: According to the preparation method of the tebuconazole molecularly imprinted membrane electrode described in the examples, prepare respectively: mercaptographene-gold nanoparticle modified electrode, gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode, polymer Membrane electrode, tebuconazole molecular imprinting membrane electrode. The tebuconazole molecularly imprinted membrane electrode adsorbing 0.1 mmol/L tebuconazole is obtained by placing the tebuconazole molecularly imprinted membrane electrode obtained in Example 1 in a 0.1 mmol/L tebuconazole solution and stirring for 30 min.

The electrodes to be tested are measured by cyclic voltammetry, the potential range is 0.5-0.1V, and the electrolyte is 0.1mol L ^-1 potassium nitrate solution. The cyclic voltammetry obtained is shown in Figure 4.

The measurement results are shown in Figure 4, in the figure: a is the cyclic voltammogram of the mercaptographene-gold nanoparticles modified electrode, b is the cyclic voltammogram of the gold-Prussian blue-mercaptographene-gold nanoparticles modified electrode, c is the cyclic voltammogram of the polymer membrane electrode, d is the cyclic voltammogram of the tebuconazole molecularly imprinted membrane electrode, and e is the tebuconazole molecularly imprinted membrane electrode adsorbed with 0.1 mmol/L tebuconazole.

The peak current value of curve b is significantly enhanced relative to curve a, indicating that the electron transfer efficiency is increased after the modification of gold-Prussian blue, that is, the modification of gold-Prussian blue can improve the sensitivity of the electrode.

Curve c is a gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode modified with a polymer film with template molecules. Compared with curve b, the current value is significantly lower and the degree of closure is increased, indicating that the modified electrode has template molecules The reduction of Prussian blue electrical signal after the polymer film is mainly due to the compact structure of the polymer film, which blocks the electronic signal transfer of the probe molecule Prussian blue.

Compared with the curve c, the redox peak appeared again in the curve d, indicating that the tebuconazole molecules in the polymer membrane were successfully removed after being treated with the mixed solution of methanol and acetic acid, leaving imprints on the surface of the tebuconazole molecularly imprinted membrane electrode The hole and the recognizable site enable the tebuconazole molecule in the sample to be tested to specifically bind to the imprinted hole, thereby realizing the specific detection of the tebuconazole molecule.

Curve e is the tebuconazole molecularly imprinted membrane electrode that adsorbs 0.1mmol/L tebuconazole. Since part of the imprinted sites are occupied by tebuconazole, the Prussian blue electrical signal is blocked by part of the imprinted sites, so that the peak current relative to the curve The peak current of d decreases, indicating that the present invention can calculate the content of tebuconazole adsorbed in the tebuconazole molecularly imprinted membrane electrode by measuring the change of the peak current value before and after sample adsorption, and then can be used for the quantitative determination of tebuconazole.

Example 7

The tebuconazole molecularly imprinted membrane electrode prepared in Example 1 was used as the working electrode, the platinum electrode was used as the counter electrode, and the calomel electrode was used as the reference electrode to form a three-electrode system; the electrolyte solution was potassium nitrate with a pH of 7.0 and 0.1 mol/L solution. The above materials were combined to make a portable sensor for tebuconazole.

Example 8

The tebuconazole molecularly imprinted membrane electrode prepared in Example 2 was used as the working electrode, the platinum electrode was used as the counter electrode, and the calomel electrode was used as the reference electrode to form a three-electrode system; the electrolyte solution was potassium nitrate with a pH of 5.0 and 0.08 mol/L solution. The above materials were combined to make a portable sensor for tebuconazole.

Example 9

The tebuconazole molecularly imprinted membrane electrode prepared in Example 3 was used as the working electrode, the platinum electrode was used as the counter electrode, and the calomel electrode was used as the reference electrode to form a three-electrode system; the electrolyte solution was potassium nitrate with a pH of 8.0 and 0.14 mol/L solution. The above materials were combined to make a portable sensor for tebuconazole.

Comparative example 1

The glassy carbon electrode was soaked in a mixed solution of 30% hydrogen peroxide and concentrated sulfuric acid with a volume ratio of 1:3 for 20 minutes, polished with 0.05 μm Al ₂ O ₃ until the surface of the electrode was mirror-like, washed with water, and ultrasonicated in water for 10 minutes. Dry the electrode after ultrasonication with nitrogen, place it in 0.5 mol/L dilute sulfuric acid solution, and scan 20 cycles in the voltage range of -0.2 ~ 1.6V by cyclic voltammetry. After scanning, the electrode was washed with water and dried with nitrogen gas to obtain the pretreated substrate electrode.

Place the pretreated substrate electrode in 3mmol/L tetrachloroalloy acid solution, and use the constant potential method to electrodeposit at a voltage of -0.2V for 100s, so that gold nanoparticles are deposited on the surface of the substrate electrode to obtain a gold nanoparticle modified electrode. .

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and the gold-Prussian blue was deposited by cyclic voltammetry under the conditions of a potential range of 0-1.0V, a scan rate of 50mV/s, and 17 cycles of scanning to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.1mol/L potassium nitrate, 1mmol/L tetrachloroalloy acid and 1mmol/L potassium ferrocyanide.

The gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode was placed in a phosphate buffer solution containing tebuconazole, o-aminophenol and resorcinol, and cyclic voltammetry was used in the potential range of -0.4 to 1.0V, Under the conditions of scanning rate 50mV/s and scanning 9 circles, polymerize into a tebuconazole molecularly imprinted film containing template molecules and modify it on the gold-Prussian blue surface of the electrode. After washing with water, dry it with nitrogen and let it stand for 5 hours to obtain a polymer membrane electrode. The concentration of the phosphate buffer is 0.05mmol/L, and the pH value is 7.0; the concentration of tebuconazole in the phosphate buffer is 0.7mmol/L, and the concentrations of o-aminophenol and resorcinol are both 2.1mmol/L.

The polymer membrane electrode was placed in a mixed solution of methanol and acetic acid with a volume ratio of 1:9 to remove template molecules, stirred at 120 rpm for 30 min, and washed with water to obtain a comparative electrode 1.

The comparative electrode 1 was used as the working electrode, the platinum electrode was used as the counter electrode, and the calomel electrode was used as the reference electrode to form a three-electrode system; the electrolyte solution was potassium nitrate solution with pH 7.0 and 0.1 mol/L. The above-mentioned material composition was made into a comparative sensor 1 .

The difference between comparative sensor 1 and the tebuconazole portable sensor described in Example 7 is that the working electrode used in comparative sensor 1 is unmodified mercapto graphene.

Comparative example 2

The glassy carbon electrode was soaked in a mixed solution of 30% hydrogen peroxide and concentrated sulfuric acid with a volume ratio of 1:3 for 20 minutes, polished with 0.05 μm Al ₂ O ₃ until the surface of the electrode was mirror-like, washed with water, and ultrasonicated in water for 10 minutes. Dry the electrode after ultrasonication with nitrogen, place it in 0.5 mol/L dilute sulfuric acid solution, and scan 20 cycles in the voltage range of -0.2 ~ 1.6V by cyclic voltammetry. After scanning, the electrode was washed with water and dried with nitrogen gas to obtain the pretreated substrate electrode.

Place the pretreated substrate electrode in 3mmol/L tetrachloroalloy acid solution, and use the constant potential method to electrodeposit at a voltage of -0.2V for 100s, so that gold nanoparticles are deposited on the surface of the substrate electrode to obtain a gold nanoparticle modified electrode. .

The gold nanoparticle-modified electrode was placed in a 0.25 mg/mL mercaptographene aqueous solution, and allowed to stand for 4 hours to obtain a mercaptographene-gold nanoparticle-modified electrode.

The mercaptographene-gold nanoparticle modified electrode was placed in the mixed solution, and the gold-Prussian blue was deposited by cyclic voltammetry under the conditions of a potential range of 0-1.0V, a scan rate of 50mV/s, and 17 cycles of scanning to obtain gold- Prussian blue-mercaptographene-gold nanoparticles modified electrodes. The mixed solution is 0.1mol/L potassium nitrate, 1mmol/L tetrachloroalloy acid and 1mmol/L potassium ferrocyanide.

The gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode was placed in a phosphate buffer containing o-aminophenol and resorcinol, and cyclic voltammetry was used in the potential range of -0.4 to 1.0V at a scan rate of 50mV/ s. Prepare non-molecularly imprinted film (NIP) by in-situ electropolymerization under the condition of scanning 9 circles, and modify the gold-Prussian blue surface of the electrode. After washing with water, blow dry with nitrogen and let it stand for 5 hours to obtain NIP polymer film modification electrode. The concentration of the phosphate buffer solution is 0.05mmol/L, and the pH value is 7.0; the concentrations of o-aminophenol and resorcinol in the phosphate buffer solution are independently 2.1mmol/L.

The polymer membrane electrode was placed in a mixed solution of methanol and acetic acid with a volume ratio of 1:9 to remove template molecules, stirred at 120 rpm for 30 min, and washed with water to obtain a comparative electrode 2.

The contrast electrode 2 is used as the working electrode, the platinum electrode is used as the counter electrode, and the calomel electrode is used as the reference electrode to form a three-electrode system; the electrolyte solution is potassium nitrate solution with pH 7.0 and 0.1 mol/L. The above-mentioned material composition was fabricated into a comparative sensor 2 .

The difference between the comparative sensor 2 and the tebuconazole portable sensor described in Example 7 is that the working electrode used in the comparative sensor 2 is modified with a non-molecularly imprinted membrane NIP.

Example 10

This test uses differential pulse voltammetry to measure the linear range of the portable sensor and draws a standard curve, and compares the detection sensitivity of the portable sensor obtained in Example 7 with the comparative sensor 1 and comparative sensor 2 obtained in comparative example 1 and comparative example 2.

Preparation of standard series: prepare standard series with concentrations of 0, 0.00005, 0.0002, 0.0005, 0.001, 0.006, 0.03, 0.1, 0.2 and 0.4 mmol/L by taking tebuconazole standard substance respectively.

Detection objects: the portable sensor obtained in Example 7, the comparative sensor 1 obtained in Comparative Example 1, and the comparative sensor 2 obtained in Comparative Example 2.

Detection method: suspend the working electrode of each detection object in the sample to be tested, absorb for 15 minutes, and wash with water after the adsorption is completed. Differential pulse voltammetry is used to form a three-electrode system at a working electrode, a platinum electrode, and a calomel electrode, and detection is performed in a potassium nitrate solution of pH 7.0 and 0.1mol/L. The conditions of the differential pulse voltammetry are preferably: voltage 0.5～-0.1V, pulse width 50ms, time interval 0.5s, step potential 5mV, modulation amplitude 50mV. Record the differential pulse voltammetry scanning curve and the maximum response current value obtained from the test, and the electrochemical response time is 1.5min.

The result is shown in Figure 5, in the figure:

The curve from top to bottom is the difference obtained by using the tebuconazole portable sensor described in Example 7 to measure concentrations of 0, 0.00005, 0.0002, 0.0005, 0.001, 0.006, 0.03, 0.1, 0.2 and 0.4mmol/L standard series Pulse voltammetry scan curve.

The illustration of Figure 5 is the standard curve of the sample concentration logarithmic value-current response change value obtained by the tebuconazole portable sensor composed of different modified working electrodes for measuring standard series samples, in the figure:

The standard curve obtained for the portable sensor using the tebuconazole molecularly imprinted membrane electrode prepared in Example 1 as the working electrode, the curve equation is as follows:

ΔI=4.95LogC+26.64,

In the formula, △I represents the change value of the sample current value in response, and the unit is μA;

C represents the concentration of tebuconazole in the sample, unit mmol/L;

The correlation coefficient R ² of the curve equation is 0.971;

The standard curve obtained for the portable sensor with the comparative electrode 1 prepared in Comparative Example 1 as the working electrode, the curve equation is as follows:

△I＝3.86LogC+9.11

In the formula, △I represents the change value of the sample current value in response, and the unit is μA;

C represents the concentration of tebuconazole in the sample, unit mmol/L;

The correlation coefficient R ² of the curve equation = 0.996;

▲It is the standard curve obtained for the portable sensor using the non-molecularly imprinted membrane electrode prepared in Comparative Example 2 as the working electrode. The curve equation is as follows:

ΔI=1.23LogC+6.20,

In the formula, △I represents the change value of the sample current value in response, and the unit is μA;

C represents the concentration of tebuconazole in the sample, unit mmol/L;

The correlation coefficient R ² =0.976 for the curve equation.

It can be seen from Figure 5 that the tebuconazole portable sensor obtained in Example 7 is linear in the concentration of tebuconazole in the range of 0.0005-0.4mmol/L and the change value of the current response is linear, and the change value of the current response is determined by the working electrode when the sample is adsorbed. The difference between the maximum response current value and the maximum response current value obtained during the measurement of the working electrode after absorbing the sample.

From the illustration in Figure 5, it can be seen that the slope of the ■ curve is higher than that of the ● curve and the ▲ curve, indicating that the tebuconazole portable sensor provided by the present invention works relative to the working electrode of unmodified mercaptographene or modified non-molecularly imprinted membrane The sensor composed of electrodes has higher detection sensitivity. It can be seen that the modified mercaptographene and tebuconazole molecularly imprinted membrane on the molecularly imprinted membrane of the present invention can effectively improve the sensitivity of quantitative detection, and the detection limit of the tebuconazole portable sensor provided by the present invention can reach 1.63×10 ^-8 mol /L.

Example 11

In this experiment, the tebuconazole portable sensor and the comparative sensor 2 were used to quantitatively measure tebuconazole and tebuconazole structural analogues to test the selectivity of the tebuconazole portable sensor.

Detection object: the tebuconazole portable sensor obtained in Example 7, and the comparative sensor 2 obtained in Comparative Example 2. The difference between the two lies in whether the tebuconazole molecularly imprinted membrane is modified.

Sample determination: get respectively the standard substance of tebuconazole, triaconazole, bifentriazole, penconazole, myclobutanil and acetamiprid, be mixed with the sample solution of 0.1mmol/L, described triaconazole, Bifentriazole, penconazole, myclobutanil and acetamiprid are structural analogues of tebuconazole.

Experimental method: Suspend the working electrode in the sample solution to be tested, absorb for 15 minutes, and wash with water after the adsorption is completed. Adopt differential pulse voltammetry to measure in the three-electrode system that the working electrode after adsorbing sample, platinum electrode, calomel electrode form, the electrolytic solution that uses is the potassium nitrate solution of pH7.0, 0.1mol/L, described differential The preferred pulse voltammetry conditions are: voltage 0.5-0.1V, pulse width 50ms, time interval 0.5s, step potential 5mV, modulation amplitude 50mV. . Record the maximum response current value measured by each sample and each sensor. The electrochemical response time is 1.5min.

The test results are shown in Figure 6, in the figure:

MIP represents the portable sensor described in Example 7, and NIP represents the comparative sensor 2 obtained in Comparative Example 2;

△I is the difference between the maximum response current value measured after the adsorption of the sample and the maximum response current value measured before the adsorption;

△I _M is the △I value measured by MIP, and △I _N is the △I value measured by NIP;

IF is the ratio of _{△ IM} to △IN, which is mainly used to evaluate the selectivity of the working electrode in the portable sensor to the target compound and its structural analogues.

As can be seen from Figure 6, MIP measures the ΔI value of tebuconazole significantly higher than the ΔI value of triaconazole, bifentriazole, penconazole, myclobutanil and acetamiprid, illustrating that the present invention provides The maximum response current change value of tebuconazole sample measured by the tebuconazole portable sensor was significantly different from that of triaconazole, bifentriazole, penconazole, myclobutanil and acetamiprid; while NIP The △I value of tebuconazole was not significantly different from that of triaconazole, bifentriazole, penconazole, myclobutanil and acetamiprid, which indicated that the comparison sensor 2 was used for tebuconazole and its structure. The response values of the analogues are close, and it is impossible to clearly distinguish tebuconazole and its structural analogues. The content of tebuconazole structural analogues may interfere with the quantitative determination of tebuconazole.

It can be seen that the electrode modified with the tebuconazole molecularly imprinted membrane has a stronger specificity for the detection of tebuconazole than the electrode modified with the non-molecularly imprinted membrane, that is, the tebuconazole molecularly imprinted membrane electrode provided by the present invention has a higher specificity for the detection of tebuconazole. The specificity of the quantitative detection is stronger, and the influence of the structural analogue of tebuconazole on the quantitative determination result is effectively avoided.

At the same time, the IF value of tebuconazole in Figure 6 is significantly higher than that of triaconazole, bifonazole, penconazole, myclobutanil and acetamiprid. The IF value is the ratio of △I _M to △ _IN , and IF The larger the value, the stronger the selectivity of the electrode to the target compound in the tebuconazole portable sensor. It can be seen that the tebuconazole molecularly imprinted membrane electrode provided by the present invention has strong selectivity to tebuconazole, and can effectively distinguish tebuconazole and its structural analogues.

Example 12

In this test, the tebuconazole portable sensor obtained in any one of Examples 7 to 9 was used to measure the tebuconazole contained in cucumbers and green vegetables, so as to test the accuracy of the tebuconazole portable sensor.

Sample preparation: after crushing and homogenizing 500g cucumber or green vegetables, weigh 25g (accurate to 0.01g) homogenate sample, add tebuconazole standard respectively, so that the concentrations of tebuconazole in the homogenate sample are: 0.020mg/ kg, 0.100mg/kg and 0.500mg/kg. Let it stand for 30 minutes, add 50 mL of acetonitrile for extraction, homogenize the mixed solution with a high-speed homogenizer, transfer it to a centrifuge tube, and centrifuge at 5000 rpm for 5 minutes, take 1 mL of the supernatant extract, add 3 mL of water, mix well and then test the sample.

Experimental method: suspend the tebuconazole molecularly imprinted membrane electrode in the sample to be tested, absorb for 15 minutes, and wash with water after the adsorption is completed. Time difference pulse voltammetry is adopted to measure in a three-electrode system composed of tebuconazole molecularly imprinted membrane electrode, platinum electrode and calomel electrode, the electrolyte solution is potassium nitrate solution of pH7.0, 0.1mol/L, and the differential The preferred pulse voltammetry conditions are: voltage 0.5-0.1V, pulse width 50ms, time interval 0.5s, step potential 5mV, modulation amplitude 50mV. Record the differential pulse voltammetry scan curve and the maximum response current value obtained from the test. The electrochemical response time is 1.5min.

The standard curve (Fig. 5 insert) obtained in Example 10 is used to calculate the maximum response current value obtained by the test, and then multiply the dilution factor to obtain the content of tebuconazole in the sample, and calculate the recovery rate of tebuconazole in the sample And the relative standard deviation, the specific results are shown in Table 1.

Content and recovery rate of tebuconazole in table 1 cucumber and green vegetables

As can be seen from Table 1, using the tebuconazole portable sensor provided by the invention to measure the content of tebuconazole in cucumbers and green vegetables, the recovery rate can reach 77.90-118.69%, and the RSD value is less than 10%, which shows that the tebuconazole provided by the invention is portable. The sensor has high measurement accuracy and can meet the requirements of on-site detection of pesticide residues.

The above is only a preferred embodiment of the present invention, and it should be pointed out that for those of ordinary skill in the art, some improvements and modifications can be made without departing from the principle of the present invention. It should be regarded as the protection scope of the present invention.

Claims (10)

1. A tebuconazole molecularly imprinted membrane electrode, comprising a base electrode, sequentially modifying gold nanoparticles, mercaptographene and gold-Prussian blue on the surface of the base electrode, and tebuconazole attached to the surface of the gold-Prussian blue Alcohol molecularly imprinted membrane; The tebuconazole molecularly imprinted membrane is an o-aminophenol and resorcinol polymer with tebuconazole as a template molecule. 2. A method for preparing a tebuconazole molecularly imprinted membrane electrode, comprising the following steps: (1) placing the substrate electrode in a tetrachloroalloy acid solution, performing electrodeposition by a constant potential method, depositing gold nanoparticles on the surface of the substrate electrode, and obtaining a gold nanoparticle modified electrode; (2) The gold nanoparticle modified electrode obtained in the step (1) is left standing in the aqueous solution of mercaptographene, so that the mercaptographene is modified on the gold nanoparticle surface of the electrode to obtain the mercaptographene-gold nanoparticle modification electrode; (3) The mercaptographene-gold nanoparticle modified electrode obtained in the step (2) is placed in a mixed solution containing potassium nitrate, tetrachloroalloy acid and potassium ferrocyanide, and gold-nanoparticles are deposited by cyclic voltammetry. Prussian blue particles to obtain a gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode; (4) placing the gold-Prussian blue-mercaptographene-gold nanoparticle modified electrode obtained in the step (3) in a phosphate buffer containing tebuconazole, o-aminophenol and resorcinol for electropolymerization, Obtain a polymer film modified electrode; (5) placing the polymer membrane modified electrode in the step (4) in a mixed solution of methanol and acetic acid to remove tebuconazole molecules in the polymer membrane to obtain a tebuconazole molecularly imprinted membrane electrode. 3. The preparation method according to claim 2, characterized in that the concentration of the tetrachloroalloy acid solution in step (1) is 2.5-3.5 mmol/L, and the electrodeposition time is 80-150 s. 4. The preparation method according to claim 2 or 3, characterized in that, the concentration of the graphene mercapto aqueous solution in step (2) is 0.25 to 0.5 mg/mL, and the standing time is 2 to 6 hours. 5. preparation method according to claim 2 is characterized in that, the concentration of potassium nitrate in the mixed solution described in step (3) is 0.05～0.2mol/L, the concentration of tetrachloroalloy acid is 0.5～1.5mmol/L And the concentration of potassium ferrocyanide is 0.5-1.5 mmol/L; the conditions of the cyclic voltammetry are: the potential range is 0-1.0V, the scan rate is 50mV/s, and the scan is 15-30 cycles. 6. The preparation method according to claim 2, characterized in that, in the phosphoric acid mixed solution described in step (4), the concentrations of o-aminophenol and resorcinol are independently 2.0 to 2.5mmol/L, and tebuconazole The concentration of phosphate buffer is 0.5-1mmol/L, the concentration of phosphate buffer is 0.01-0.07mmol/L; the electropolymerization conditions are: potential range -0.4-1.0V, scan rate 50mV/s, scan 8-10 circles. 7. The preparation method according to claim 2, characterized in that, in the mixed solution of methanol and acetic acid described in step (5), the volume ratio of methanol and acetic acid is 1:7˜1:11. 8. A portable sensor for the quantitative determination of tebuconazole, comprising a working electrode, a counter electrode, a reference electrode and an electrolyte solution, characterized in that, the working electrode is the tebuconazole molecularly imprinted membrane according to claim 1 For the electrode or the tebuconazole molecularly imprinted membrane electrode obtained by the preparation method described in any one of claims 2-8, the electrolyte solution is a potassium nitrate solution with a pH value of 5.0-8.0 and a concentration of 0.08-0.14 mol/L. 9. The application of the tebuconazole molecularly imprinted membrane electrode as claimed in claim 1 or the portable sensor as claimed in claim 8 in the determination of tebuconazole pesticide residues in agricultural products. 10. application according to claim 9, the method for described measurement agricultural product tebuconazole pesticide residue comprises the following steps: 1) Suspend the tebuconazole molecularly imprinted membrane electrode in the sample solution, and absorb for 10-20 minutes; 2) Use the tebuconazole molecularly imprinted membrane electrode adsorbed in the step (1) as a working electrode, form a three-electrode system with a counter electrode and a reference electrode, perform an electrochemical test in an electrolyte solution, and record the differential obtained from the test. Pulse voltammetry scanning curve and maximum response current value; 3) calculate the content of tebuconazole in the sample solution according to the maximum response current value of the sample solution obtained by the standard curve and the step (2); The standard curve is a linear curve between the maximum response current value of the differential pulse voltammetry test and the concentration of tebuconazole.