CN114839242B - Electrochemical sensor for detecting pesticides, preparation method and application thereof - Google Patents
Electrochemical sensor for detecting pesticides, preparation method and application thereof Download PDFInfo
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/308—Electrodes, e.g. test electrodes; Half-cells at least partially made of carbon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y40/00—Manufacture or treatment of nanostructures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
Abstract
The invention provides an electrochemical sensor for detecting pesticides, a preparation method and application thereof. The electrochemical sensor is composed of PtNPs/UiO-66-NH 2 The MWCNTs nano composite material is modified on the surface of the glassy carbon electrode; ptNPs/UiO-66-NH 2 MWCNTs nanocomposite is referred to in UiO-66-NH 2 The MWCNTs nano composite material is modified with PtNPs nano composite material; uiO-66-NH 2 The MWCNTs nano composite material is characterized in that UiO-66-NH is modified on the surface of the MWCNTs 2 Is a nanocomposite of (a). The invention has the advantages of simple operation, no need of complex pretreatment of the sample to be detected, low detection cost, rapid detection, low requirement on detection instruments and the like when the invention is used for detecting pesticides.
Description
Technical Field
The invention relates to the technical field of pesticide residue detection, in particular to an electrochemical sensor for detecting pesticides, a preparation method and application thereof.
Background
Pesticides are used as pesticides, bactericides, herbicides and the like in agricultural production, and they mainly protect crops and plants from diseases and insect pests and weed damage, and improve the yield of crops. However, improper operation of pesticides during production, transportation and use is extremely prone to leakage and acute poisoning. In particular, with the excessive application of pesticides, pesticide residues are detected in the bodies of vast crops and cultured animals, and great harm is brought to the production and life of people. The organophosphorus pesticides are organic compound pesticides containing phosphorus elements, and approximately account for four times of the pesticide usage amount, and can cause excessive accumulation of acetylcholinesterase (ACh) in human bodies due to incapacity of hydrolysis by inhibiting the activity of acetylcholinesterase, thereby causing excessive stimulation of cholinergic neurons. Clinically, convulsions and epilepsy develop rapidly into persistent convulsions, which lead to deep brain structural damage and death within a few minutes. Therefore, the research on the pesticide residue detection method is enhanced, a high-sensitivity and high-accuracy pesticide residue analysis detection technology is developed to rapidly and timely monitor the pesticide residue in the environment and agricultural products, the scientific use of the pesticide is promoted, and the method has important significance for protecting the ecological environment and guaranteeing the physical health and life safety of people.
At present, the detection methods of pesticide residues mainly comprise two types: traditional instrumental detection analysis techniques and rapid detection methods. The traditional instrument detection method mainly focuses on chromatographic techniques, including gas chromatography, gas/liquid chromatography-mass spectrometry, high performance liquid chromatography and the like. The method has higher sensitivity and stability, but the conventional chromatographic-mass spectrometry detection and other techniques for analyzing pesticide residues have higher cost and long detection time, and most of the defects of expensive equipment, large solvent consumption and incapability of meeting the on-site rapid detection exist, so that the method causes a lot of inconvenience to the national food safety supervision departments for the supervision of agricultural products. In order to accurately, conveniently and rapidly detect pesticide residues in real time, a plurality of rapid detection methods are developed, one of which is a spectrophotometry, but the method has the defects of low accuracy, high detection limit, low sensitivity and the like, so that the application of the spectrophotometry in pesticide residue detection is greatly limited. Accordingly, there is an urgent need to conduct intensive research work in this area to establish a rapid and efficient method for separating and detecting pesticides in foods.
Disclosure of Invention
The invention aims to provide an electrochemical sensor for detecting pesticides, a preparation method and application thereof, and the electrochemical sensor can realize rapid and high-sensitivity detection of pesticides and has low detection cost.
The invention is realized in the following way: the electrochemical sensor for detecting pesticide provided by the invention is formed by PtNPs/UiO-66-NH 2 The MWCNTs nano composite material is modified on the surface of the glassy carbon electrode. Wherein PtNPs/UIO-66-NH 2 The MWCNTs nano composite material is synthesized by a simple two-step method: first, a one-pot hydrothermal method is used for synthesizing UiO-66-NH 2 MWCNTs nanocomposite, uiO-66-NH 2 Uniformly grow onThe surface of MWCNTs; ptNPs are then reduced in situ to UiO-66-NH 2 MWCNTs material surface.
One-pot hydrothermal synthesis of UiO-66-NH 2 The method of the MWCNTs nano composite material is specifically as follows:
ZrCl is added to 4 MWCNTs and NH 2 Adding BDC into DMF solution, adding glacial acetic acid, reacting at 120 ℃ for 12 hours in an autoclave, naturally cooling, centrifuging, washing with DMF and ethanol to obtain UiO-66-NH 2 MWCNTs material.
Preferably, uiO-66-NH is synthesized 2 ZrCl in the process of MWCNTs nano composite material 4 MWCNTs and NH 2 The mass ratio of BDC is 233:300:181.
In the preparation of UiO-66-NH 2 After the MWCNTs nano composite material, uiO-66-NH 2 Adding MWCNTs into water, and performing ultrasonic treatment for 0.5 hr to obtain 1mg/mL UiO-66-NH 2 MWCNTs suspension; then 1% H is added 2 PtCl 6 ·6H 2 O, ultrasonic for 1 hour, then sequentially adding 1% trisodium citrate solution and freshly prepared 0.075% NaBH 4 Stirring the solution continuously for 12 hours, centrifuging, washing with ethanol to obtain PtNPs/UiO-66-NH 2 MWCNTs nanocomposite.
PtNPs/UIO-66-NH as described above 2 1%H in the preparation method of the MWCNTs nanocomposite 2 PtCl 6 ·6H 2 O solution with 1mg/mL UiO-66-NH 2 The volume ratio of the MWCNTs suspension is 6:100.
Based on the technical scheme, the invention provides a preparation method of an electrochemical sensor, which comprises the following specific steps:
PtNPs/UiO-66-NH 2 Adding the MWCNTs material into water to form PtNPs/UIO-66-NH 2 And (3) dripping the MWCNTs suspension liquid on the surface of the glassy carbon electrode, naturally drying, and forming a uniform modification layer on the surface of the electrode to obtain the electrochemical sensor.
The glass carbon electrode is positioned in PtNPs/UiO-66-NH 2 The MWCNTs suspension is polished and cleaned before being coated by liquid drops, and the treatment method is as follows: with Al of 1.0 μm, 0.3 μm and 0.05 μm, respectively 2 O 3 The polishing powder sequentially polishes the glassy carbon electrode, and after polishing, the electrode is washed with water, and the ear ball is quickly dried for later use. Preferably, the water washing process uses ultrapure water.
The electrochemical sensor prepared by the invention can be used for detecting pesticide residues, including but not limited to detection of organophosphorus pesticides, wherein the electrochemical sensor has the best selectivity to organophosphorus pesticides, such as methyl parathion.
The invention provides a method for detecting pesticides by using an electrochemical sensor prepared by the method, which comprises the following specific steps:
(1) Construction of differential pulse voltammetry curves for pesticides
Diluting the pesticide PBS buffer solution into standard vertebral solutions with different concentrations, placing the electrochemical sensor in the standard solutions with different concentrations, enriching under constant voltage to enable the pesticide to be adsorbed on the working electrode, and detecting by using a differential pulse voltammetry to obtain a differential pulse voltammetry curve.
(2) Construction of pesticide concentration-amperage Standard Curve
And constructing a pesticide concentration-current intensity standard curve by taking the pesticide concentration as an abscissa and the current intensity in the differential pulse voltammetry as an ordinate.
(3) Detecting pesticide residues in a sample
And (3) placing the electrochemical sensor in a sample solution to be detected, enriching under constant voltage, enabling the pesticide to be adsorbed on the working electrode, detecting by using a differential pulse voltammetry, recording a differential pulse voltammetry curve of the sample solution, and obtaining the concentration of the pesticide in the sample to be detected by comparing with a pesticide concentration-current intensity standard curve.
The electrochemical detection cell is a three-electrode system, wherein an electrochemical sensor is a working electrode, ag/AgCl (3M KCl solution) is a reference electrode, a platinum wire electrode is an auxiliary electrode, and a PBS buffer solution with the concentration of 0.1M is used as an electrolyte solution.
Taking methyl parathion as an example to describe the detection principle of the electrochemical sensor, the detection principle of the electrochemical sensor comprises the following steps:
the MWCNTs material provides a large specific surface area, MWCNTss and UiO-66-NH 2 Affinity with a certain specificity for thiophosphate group on methyl parathion structure, MWCNTs, uiO-66-NH 2 The combination with PtNPs can synergistically amplify the conductivity and sensitivity of the whole electrochemical sensor, and by means of the good conductivity of the modified electrode, obvious reduction peaks appear in the electrochemical detection process, so that the qualitative detection of the methyl parathion pesticide is realized. In addition, as the concentration of the methyl parathion increases, the current intensity also obviously increases, so that the concentration of the methyl parathion in the solution to be detected is obtained by comparing with a standard curve.
The invention leads the novel organometallic framework material UiO-66-NH 2 Combining with carbon nano tube to make UiO-66-NH 2 Evenly distributed on the two-dimensional carbon nano tube material to increase the conductivity. The further combination of the platinum nano particles can synergistically amplify the electrocatalytic signal to realize high-sensitivity detection of pesticides, and particularly has higher specific detection effect on methyl parathion. The pesticide detection method provided by the invention has the advantages of simple operation, no need of complex pretreatment on the sample to be detected, low detection cost, rapid detection, low requirement on detection instruments and the like.
Drawings
FIG. 1 is a diagram of UiO-66-NH prepared in example 1 of the present invention 2 Transmission electron microscopy of MWCNTs.
FIG. 2 is a diagram of UiO-66-NH prepared in example 1 of the present invention 2 Scanning electron microscope image of MWCNTs.
FIG. 3 is a diagram of UiO-66-NH according to example 1 of the present invention 2 Schematic of the preparation process of MWCNTs.
FIG. 4 shows PtNPs/UIO-66-NH prepared in example 2 of this invention 2 Transmission electron microscopy of MWCNTs.
FIG. 5 shows PtNPs/UIO-66-NH prepared in example 2 of this invention 2 Scanning electron microscope image of MWCNTs.
FIG. 6 is PtNPs/UiO-66-NH according to example 2 of the present invention 2 Schematic of the preparation process of MWCNTs.
Fig. 7 is a schematic diagram of the principle of the electrochemical sensor for detecting methyl parathion according to the present invention.
FIG. 8 is a graph of differential pulse voltammograms of methyl parathion pesticides at different concentrations in example 4 of the present invention.
FIG. 9 is a graph of the standard curve between methyl parathion concentration and response peak current in example 4 of the present invention.
FIG. 10 is a graph of differential pulse voltammograms of methyl parathion detected by electrochemical sensors utilizing different modifying materials in example 5 of the present invention.
Detailed Description
The meaning of the abbreviations appearing in the present invention will be explained first, as follows:
"MWCNTs" refers to a multi-walled carbon nanotube two-dimensional material. "UiO-66-NH 2 "refers to a zirconium-based metal-organic framework material. "PtNPs" refers to platinum nanoparticles, and may also be referred to as "platinum nanoparticles", "platinum nanomaterials", and the like. "UiO-66-NH 2 MWCNTs "means MWCNTs surface-modified with UiO-66-NH 2 Is a nanocomposite of (a). "PtNPs/UiO-66-NH 2 MWCNTs "means a UiO-66-NH 2 The MWCNTs nano composite material is modified with PtNPs nano composite material. "PtNPs/UiO-66-NH 2 The MWCNTs/glassy carbon electrode refers to a PtNPs/UiO-66-NH modified on the glassy carbon electrode 2 Electrochemical sensor of MWCNTs nanocomposite.
The invention will be described in further detail below in connection with specific embodiments and with reference to the data. The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention in any way.
Example 1UiO-66-NH 2 Preparation of MWCNTs nanocomposite
58mg ZrCl 4 Adding the mixture into 50mL of DMF (N, N-dimethylformamide) solution, and carrying out ultrasonic dissolution; then 75mg MWCNTs are added and sonicated for 5 hours; 45mg of NH 2 BDC (2-amino terephthalic acid) was added and 4.5mL glacial acetic acid was added and sonication was continued for 1 hour. Adding the suspension into an autoclave at 120 ℃ for reaction for 12 hours, naturally cooling, centrifuging, washing with DMF and ethanol to obtain UiO-66-NH 2 MWCNTs nanocomposite.
Obtained UiO-66-NH 2 The transmission electron microscope graph of the MWCNTs nano composite material is shown in figure 1, and the scanning electron microscope graph is shown in figure 2. UiO-66-NH 2 The preparation process of the MWCNTs nanocomposite is shown in figure 3.
EXAMPLE 2PtNPs/UiO-66-NH 2 Preparation of MWCNTs nanocomposite
10mg of UiO-66-NH 2 MWCNTs nanocomposite was added to 10mL of water, sonicated for 0.5h, and added with 0.6mL1% H 2 PtCl 6 ·6H 2 The solution O is continuously sonicated for 1h. Then 1.5mL of 1% trisodium citrate solution, 1.5mL of absolute ethanol, and 0.3mL of freshly prepared 0.075% NaBH were added in sequence with stirring 4 A solution. The above mixed solution was stirred continuously for 12 hours. Centrifuging, washing with ethanol to obtain PtNPs/UiO-66-NH 2 MWCNTs nanocomposite.
PtNPs/UIO-66-NH obtained 2 The transmission electron microscope image of the MWCNTs nano composite material is shown in figure 4, and the scanning electron microscope image is shown in figure 5. PtNPs/UiO-66-NH 2 The preparation process of the MWCNTs nanocomposite is shown in FIG. 6.
Example 3 electrochemical sensor (PtNPs/UiO-66-NH) 2 MWCNTs/glassy carbon electrode)
(1) Polishing and cleaning the glassy carbon electrode with Al of 1.0 μm, 0.3 μm and 0.05 μm 2 O 3 Polishing powder is used for polishing the surfaces of the glassy carbon electrodes respectively, after polishing, ultrapure water is used for cleaning the electrodes, and the surfaces of the electrodes such as mirror surfaces are obtained, and the ear-washing balls are quickly dried for use.
(2) PtNPs/UiO-66-NH 2 Adding MWCNTs into water to obtain PtNPs/UiO-66-NH 2 MWCNTs suspension, concentration is 2mg/mL; mu.L PtNPs/UiO-66-NH was removed by a micropipette 2 The MWCNTs suspension is dripped on the surface of the glassy carbon electrode, preferably on the middle part, the beaker is inverted at room temperature to cover the electrode so as to naturally dry the electrode, and a uniform modification layer is formed on the surface of the electrode; stored in a refrigerator at 4 ℃ for later use.
Example 4 method for detecting methyl parathion Using electrochemical sensor
Methyl parathion was diluted with PBS buffer (0.1M) to 10mL of standard vertebral solution of 0.03, 0.1, 0.3, 1.0, 3.0, 5.0, 8.0, 10.0, 20.0, 30.0, 40.0, 50.0, 60.0mg/L, respectively, and then the electrochemical sensor prepared in example 3 was placed in the standard solutions of the above different concentrations, and constant pressure enrichment was performed at 0.3V for 6min, so that pesticides were adsorbed on the working electrode, and then detection was performed by differential pulse voltammetry, and differential pulse voltammetry was recorded and obtained by an electrochemical platform instrument (CHI 750C, shanghai Chen Hua instruments Co.).
The electrochemical detection cell is a three-electrode system, wherein a Glassy Carbon Electrode (GCE) is used as a working electrode, ag/AgCl (3 MKCl solution) is used as a reference electrode, a platinum wire electrode is used as an auxiliary electrode, and PBS phosphate buffer (0.1M) is used as an electrolyte solution. Modification of PtNPs/UiO-66-NH on a glassy carbon electrode 2 MWCNTs (i.e. the electrochemical sensor prepared in example 3), and then three electrodes are put into electrolyte solution, the glassy carbon electrode is connected with a green wire, the Ag/AgCl electrode is connected with a white wire, the platinum wire electrode is connected with a red wire, and the three-electrode system is assembled, wherein the voltage is between-0.2V and-0.8V.
The principle of detecting methyl parathion by using an electrochemical sensor is shown in fig. 7, and an electric signal is generated when methyl parathion is detected by using the electrochemical sensor. The plotted differential pulse voltammogram is shown in fig. 8, with increasing concentration of methyl parathion, the current intensity of the electrochemical differential pulse voltammogram increases continuously.
The current intensity response in the differential pulse voltammetry curve is taken as the abscissa and the methyl parathion concentration is taken as the ordinate, and a methyl parathion concentration-current intensity standard curve is constructed as shown in fig. 9: the standard curve graph between the concentration of the methyl parathion and the response peak current is drawn by using Origin operation software according to the methyl parathion differential pulse voltammetry curve obtained under the condition that the voltage is between-0.2 and-0.8V in the figure 8, so that quantitative analysis of the methyl parathion is realized, in addition, the detection range of an electrochemical sensor can be between 0.03mg/L and 60mg/L, and the detection lower limit of the electrochemical sensor can reach 6.8 mu g/L.
In the actual sample detection process, crushing the cucumber purchased in the local supermarket, then further standing for 2 hours, filtering to obtain juice, placing an electrochemical sensor in the cucumber juice (10 mL) to be detected, recording the differential pulse voltammetry curve of the sample solution, and displaying the result that the differential pulse voltammetry detection performed on the actual sample does not find methyl parathion, so that the cucumber in the local supermarket does not contain methyl parathion pesticide.
Example 5 detection Effect of electrochemical Sensors of different modification materials on methyl parathion
Bare glassy carbon electrode, uiO-66-NH is selected 2 MWCNTs/glassy carbon electrode, ptNPs/UIO-66-NH 2 MWCNTs/glassy carbon electrode (electrochemical sensor described in example 3), where "UiO-66-NH 2 MWCNTs/glassy carbon electrode "means that the glassy carbon electrode is modified with UiO-66-NH 2 Electrochemical sensors of MWCNTs composite nanomaterial; "PtNPs/UiO-66-NH 2 The MWCNTs/glassy carbon electrode refers to a PtNPs/UiO-66-NH modified on the glassy carbon electrode 2 Electrochemical sensor of MWCNTs composite nanomaterial.
The electrochemical sensors modified with different materials are respectively placed in 10mL of solution to be detected of methyl parathion (10 mg/L) diluted by PBS buffer solution (0.1M), 0.3V constant pressure enrichment is carried out for 6min, then detection is carried out by using a differential pulse voltammetry, and the differential pulse voltammetry curve of the solution is recorded by an electrochemical platform instrument (CHI 750C, shanghai Chen Hua instrument Co.). The electrochemical detection cell is a three-electrode system, wherein a Glassy Carbon Electrode (GCE) is used as a working electrode, ag/AgCl (3M KCl solution) is used as a reference electrode, a platinum wire electrode is used as an auxiliary electrode, and PBS (phosphate buffer) (0.1M) is used as an electrolyte solution.
As a result, as shown in fig. 10, the conductivity of the electrodes modified with different materials was different; compared with other electrochemical sensors, the electrochemical sensor has stronger current response to methyl parathion, more sensitive detection and better detection effect.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (9)
1. An electrochemical sensor for detecting agricultural chemical is characterized by that it is made up of PtNPs/UiO-66-NH 2 The MWCNTs nano composite material is modified on the surface of the glassy carbon electrode; ptNPs/UiO-66-NH 2 MWCNTs nanocomposite is referred to in UiO-66-NH 2 The MWCNTs nano composite material is modified with PtNPs nano composite material; uiO-66-NH 2 The MWCNTs nano composite material is characterized in that UiO-66-NH is modified on the surface of the MWCNTs 2 Is a nanocomposite of (a); ptNPs refer to platinum nanoparticles, uiO-66-NH 2 Refers to a zirconium-based metal-organic framework material formed by connecting 2-amino terephthalic acid as an organic ligand with zirconium metal ions, and MWCNTs refer to multi-wall carbon nanotubes; the electrochemical sensor is used to detect methyl parathion.
2. The preparation method of the electrochemical sensor for detecting pesticides is characterized by comprising the following steps: ptNPs/UiO-66-NH 2 Adding the MWCNTs nano composite material into water to form PtNPs/UiO-66-NH 2 MWCNTs suspension, ptNPs/UiO-66-NH 2 The MWCNTs suspension liquid is coated on the surface of the glassy carbon electrode in a dripping way, and naturally dried, and a uniform modification layer is formed on the surface of the glassy carbon electrode, so that the electrochemical sensor for detecting pesticides is obtained; ptNPs refer to platinum nanoparticles, uiO-66-NH 2 Refers to a zirconium-based metal-organic framework material formed by connecting 2-amino terephthalic acid as an organic ligand with zirconium metal ions, and MWCNTs refer to multi-wall carbon nanotubes; the pesticide is methyl parathion.
3. The method for manufacturing an electrochemical sensor for detecting agricultural chemicals according to claim 2, characterized in that PtNPs/Uio-66-NH is measured 2 Before the MWCNTs suspension is dripped on the surface of the glassy carbon electrode, firstly polishing and cleaning treatment is carried out on the glassy carbon electrode, and the treatment method is as follows: with Al of 1.0 μm, 0.3 μm and 0.05 μm, respectively 2 O 3 And polishing the glassy carbon electrode by the polishing powder in sequence, and washing the glassy carbon electrode by water after polishing, so that the ear washing ball is quickly dried.
4. The method for manufacturing an electrochemical sensor for detecting pesticides as claimed in claim 2, wherein PtNPs/UIO-66-NH 2 The preparation method of the MWCNTs nano composite material comprises the following steps:
(1) Synthesis of UiO-66-NH by one pot hydrothermal method 2 MWCNTs nanocomposite, uiO-66-NH 2 Uniformly growing on the surface of MWCNTs;
(2) In situ reduction of PtNPs in UiO-66-NH 2 MWCNTs nanocomposite surface.
5. The method for manufacturing an electrochemical sensor for detecting pesticides according to claim 4, wherein step (1) specifically comprises: zrCl is added to 4 MWCNTs and NH 2 Adding BDC into DMF solution, adding glacial acetic acid, reacting in autoclave, naturally cooling, centrifuging, washing with DMF and ethanol to obtain UiO-66-NH 2 MWCNTs nanocomposite.
6. The method for manufacturing an electrochemical sensor for detecting pesticides according to claim 4, wherein step (2) specifically comprises: uiO-66-NH 2 Adding the MWCNTs nano composite material into water to obtain UiO-66-NH 2 MWCNTs suspension; then add H 2 PtCl 6 ·6H 2 O solution, ultrasonic treatment, adding trisodium citrate solution and NaBH sequentially 4 Stirring, centrifuging and washing with ethanol to obtain PtNPs/UiO-66-NH 2 MWCNTs nanocomposite.
7. The method for manufacturing an electrochemical sensor for detecting pesticides as claimed in claim 6, wherein UiO-66-NH 2 The concentration of the MWCNTs suspension is 1mg/mL, H 2 PtCl 6 ·6H 2 The mass fraction of the O solution is 1%, the mass fraction of the trisodium citrate solution is 1%, and the NaBH is 4 The mass fraction of the solution was 0.075%.
8. The electrochemical sensor for detecting pesticides according to claim 1 and the use of the electrochemical sensor for detecting pesticides prepared according to the method of any one of claims 2 to 7 for detecting methyl parathion.
9. The use according to claim 8, characterized in that the method for detecting pesticides is specifically as follows:
(1) Construction of differential pulse voltammetry curves for pesticides
Diluting pesticide PBS buffer solution into a plurality of standard vertebral solutions with different concentrations, then placing an electrochemical sensor in the standard solutions with different concentrations, enriching under constant voltage to enable pesticide to be adsorbed on a working electrode, and then detecting by using a differential pulse voltammetry to obtain a differential pulse voltammetry curve; the working electrode is an electrochemical sensor;
(2) Construction of pesticide concentration-amperage Standard Curve
Constructing a pesticide concentration-current intensity standard curve by taking the pesticide concentration as an abscissa and the current intensity in the differential pulse voltammetry as an ordinate;
(3) Detecting pesticide residues in a sample
And (3) placing the electrochemical sensor in a sample solution to be detected, enriching under constant voltage, enabling the pesticide to be adsorbed on the working electrode, detecting by using a differential pulse voltammetry, recording a differential pulse voltammetry curve of the sample solution to be detected, and obtaining the concentration of the pesticide in the sample solution to be detected by comparing with a pesticide concentration-current intensity standard curve.
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