CN109254057B - Preparation method and application of pyrethroid insecticide electrochemical sensing electrode - Google Patents

Preparation method and application of pyrethroid insecticide electrochemical sensing electrode Download PDF

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CN109254057B
CN109254057B CN201811306722.4A CN201811306722A CN109254057B CN 109254057 B CN109254057 B CN 109254057B CN 201811306722 A CN201811306722 A CN 201811306722A CN 109254057 B CN109254057 B CN 109254057B
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pyrethroid insecticide
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张勇
刘召壹
魏琴
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University of Jinan
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Abstract

The invention discloses a preparation method of a pyrethroid insecticide electrochemical sensing electrode. Belongs to the technical field of novel nanometer functional materials and biosensing analysis. The method comprises the steps of firstly preparing an iron-cobalt bimetal layered hydroxide nanosheet array on a disposable throwable electrode, utilizing large specific surface area and high-activity hydroxyl functional groups of the iron-cobalt bimetal layered hydroxide nanosheet array and amino functional groups of polydopamine, adopting an in-situ growth method, and directly and sequentially preparing a polydopamine film containing an electronic mediator and a molecularly imprinted polymer taking a pyrethroid insecticide as a template molecule on the iron-cobalt bimetal layered hydroxide nanosheet array in sequence, wherein after the template molecule is eluted, the original position of the template molecule is changed into a cavity, namely the molecularly imprinted polymer of the template molecule is eluted, so that the pyrethroid insecticide electrochemical sensing electrode is prepared.

Description

Preparation method and application of pyrethroid insecticide electrochemical sensing electrode
Technical Field
The invention relates to a preparation method and application of an electrochemical analysis sensor. Belongs to the technical field of novel nanometer functional materials and biosensing analysis.
Background
Pyrethroid insecticides are 5-nitro-2 substituted furan derivatives and once are important anti-infective drugs. The medicines mainly comprise furazolidone, nitrofurantoin, furacilin and the like, and are mainly used for treating urinary system infection, intestinal bacterial infection and skin wound infection and used as food additives for preventing poultry intestinal infectious diseases. However, due to the genotoxicity and carcinogenic effects of furazolidone, its use in humans and animals has been banned by the Food and Drug Administration (FDA) and the European Medicines Administration (EMA) in 2005. Furthermore, the clinical importance of nitro heterocyclic compounds is high due to their cell-induced degeneration and animal carcinogenic toxicity. Therefore, the development of a method for quickly, highly selectively and sensitively detecting the pyrethroid insecticides is very important to public health and has wide market application prospect.
The molecular imprinting electrochemical sensor has high specificity selectivity, excellent stability, excellent reproducibility, wide detection range and bottom detection limit. The sensor has the advantages of simple preparation, convenient detection, high sensitivity, low cost and the like, and can be widely applied to the fields of chromatographic separation, membrane separation, solid-phase extraction, drug controlled release, chemical sensing and the like. Molecularly Imprinted Polymers (MIPs), also known as "plastic antibodies", are capable of specifically recognizing and selectively adsorbing a specific target molecule (i.e., template molecule). The molecular imprinting technology has many advantages, such as corrosion resistance of organic reagents, good stability, high temperature resistance and simple preparation. Thus, MIP electrochemical sensors based on MIP in combination with electrochemical sensors (MIP-ECS) have attracted a hot interest in the field of electroanalytical chemistry, especially the detection of small molecule contaminants, over the last few years. However, in the preparation process of the traditional MIP-ECS, the defects of difficult elution of template molecules, difficult control of the thickness of the imprinted membrane, poor reproducibility and the like exist, and the application of the molecularly imprinted membrane in an electrochemical sensor is limited. The problems, especially the technical problems that the sensitivity of the electrochemical sensor is reduced due to the fact that the thickness of the molecularly imprinted membrane is not easy to control, and the stability and the reproducibility are reduced due to the fact that the molecularly imprinted membrane is easy to fall off from the surface of an electrode in the elution process, limit the application of MIP _ ECS, so that the research of a new molecularly imprinted polymer synthesis method, a new molecularly imprinted membrane electrode modification method and a method for combining the molecularly imprinted membrane and a substrate material for solving the preparation and application problems of MIP-ECS has important research significance and market value.
Disclosure of Invention
The invention aims to provide a preparation method of the electrochemical sensing electrode of the pyrethroid insecticide, which has the advantages of strong specificity, simple preparation, convenient detection, high sensitivity and low cost. Based on the purpose, firstly, an iron-cobalt bimetal layered hydroxide nanosheet array is prepared on a disposable throwable electrode, a polydopamine film containing an electron mediator and a molecularly imprinted polymer taking a pyrethroid insecticide as a template molecule are sequentially and directly prepared on the iron-cobalt bimetal layered hydroxide nanosheet array in an in-situ growth method by utilizing the large specific surface area and the high-activity hydroxyl functional group of the array and the amino functional group of the polydopamine, and after the template molecule is eluted, the original position of the template molecule is changed into a cavity, namely the molecularly imprinted polymer of the template molecule is eluted, so that the pyrethroid insecticide electrochemical sensing electrode is prepared. When the electrochemical sensing electrode is used for detecting pyrethroid insecticides, the pyrethroid insecticide electrochemical sensing electrode is inserted into a solution to be detected, and the pyrethroid insecticide in the solution to be detected is adsorbed into a hole of the NIP. The greater the concentration of the pyrethroid insecticides in the solution to be tested, the more pyrethroid insecticides are adsorbed in the holes of the NIP. When electrochemical detection is carried out, the intensity of the detection current is reduced along with the increase of the pyrethroid insecticides adsorbed in the holes of the NIP, so that the concentration of the pyrethroid insecticides in the solution to be detected can be qualitatively and quantitatively determined according to the reduction degree of the current intensity.
The technical scheme adopted by the invention is as follows:
1. a preparation method of a pyrethroid insecticide electrochemical sensing electrode is provided, wherein the pyrethroid insecticide electrochemical sensing electrode is obtained by in-situ growth of a template-free molecularly imprinted polymer NIP on an iron-cobalt bimetallic layered hydroxide nanosheet array electrode FeCo LDH-nanoarray; the template-free molecularly imprinted polymer NIP is a molecularly imprinted polymer without template molecules; the molecularly imprinted polymer without the template molecule is obtained by eluting the template molecule from a MIP containing the template molecularly imprinted polymer; the MIP containing the template molecule engram polymer is the MIP containing the template molecule; the template molecule is a pyrethroid insecticide;
2. the preparation method of the FeCo bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray in the technical scheme 1 comprises the following preparation steps:
(1) carrying out ultrasonic cleaning treatment on the disposable throwable electrode by respectively using dilute hydrochloric acid, absolute ethyl alcohol and deionized water so as to remove an oxide layer and surface impurities of the disposable throwable electrode;
(2) weighing 1-3 mmol Fe (NO)3)3And Co (NO)3)2And 3 to 9mmol of urea CO (NH)2)2Placing the mixture into a 50mL beaker, adding 30mL deionized water, stirring until the mixture is clear, and then transferring the mixture into a 50mL polytetrafluoroethylene reaction kettle;
(3) putting the disposable throwable electrode processed in the step (1) into the solution in the reaction kettle in the step (2), and reacting at the temperature of 100-130 ℃ for 9-12 hours to prepare a precursor electrode of the Fe-Co bimetal layered hydroxide nanosheet array;
(4) inserting the precursor electrode of the iron-cobalt bimetal layered hydroxide nanosheet array obtained in the step (3) into phosphate buffer solution PBS containing dopamine, ammonium persulfate and cobalt nitrate, reacting for 4-6 hours at the temperature of 20-40 ℃, taking out, and performing immersion washing for 2-4 times by using deionized water to prepare an iron-cobalt bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray;
the disposable and disposable electrode is selected from one of the following electrodes: foam nickel, foam copper, pure nickel sheets, pure copper sheets, pure cobalt sheets, pure silicon sheets and conductive carbon cloth; said Fe (NO)3)3And Co (NO)3)2In a mixture of 1: 1;
in the phosphate buffer solution PBS containing dopamine, ammonium persulfate and cobalt nitrate: the concentration of dopamine is 2-5 mg/mL, the concentration of ammonium persulfate is 3-8 mg/mL, the concentration of cobalt nitrate is 0.1-0.5 mg/mL, the concentration of phosphate buffer solution PBS is 0.1mol/L, and the pH value is 7.2-8.5;
3. the preparation method of the template-containing molecularly imprinted polymer MIP with FeCo LDH-nanoarray in-situ growth described in the technical scheme 1 comprises the following preparation steps:
(1) respectively weighing 0.25-0.45 mmol of template molecules and 3-5 mmol of 2-methacrylic acid MAA in an ampoule bottle, adding 8-15 mL of acetonitrile, and carrying out ultrasonic treatment for 30min until all the template molecules and the 2-methacrylic acid MAA are dissolved;
(2) adding 15-25 mmol of ethylene glycol dimethacrylate EDMA into the solution obtained in the step (1), and carrying out ultrasonic treatment for 30min until the mixture is uniformly mixed to obtain a precursor mixed solution;
(3) clamping FeCo LDH-nanoarray prepared in the technical scheme 2 onto a rotary stirrer, inserting the FeCo LDH-nanoarray into the precursor mixed solution in the step (2), and adding N2Under the temperature of an environment and a water bath of 20-40 ℃, rotationally stirring at the speed of 5-200 r/s, simultaneously dropwise adding 1mmol of azobisisobutyronitrile AIBN into the mixed solution at the speed of 1-20 d/s to initiate polymerization, and obtaining the in-situ grown MIP on FeCo LDH-nanoarray;
4. the preparation steps of the FeCo LDH-nanoarray in-situ grown template-free molecularly imprinted polymer NIP in the technical scheme 1 are as follows: immersing the MIP which is obtained in the technical scheme 3 and grows in situ on FeCo LDH-nanoarray and contains the template molecularly imprinted polymer into an eluant, eluting the template molecule for 5-20 min at room temperature, and then taking out to obtain the NIP without the template molecularly imprinted polymer; the eluent is a mixed solution of formic acid and methanol, wherein the volume ratio of the formic acid to the methanol is 9 (1-5);
5. the preparation steps of the pyrethroid insecticide electrochemical sensing electrode in the technical scheme 1 are as follows: washing the template-free molecularly imprinted polymer NIP which grows on FeCo LDH-nanoarray in situ and is prepared in the technical scheme 2-4 times by using deionized water, and airing at room temperature to prepare the pyrethroid insecticide electrochemical sensing electrode;
6. the electrochemical sensing electrode for pyrethroid insecticides prepared by the technical scheme 1-5 is applied to the detection of pyrethroid insecticides, and comprises the following application steps:
(1) preparing a standard solution: preparing a group of pyrethroid insecticide standard solutions with different concentrations including blank samples;
(2) modification of a working electrode: taking the electrochemical sensing electrode of the pyrethroid insecticide as a working electrode, inserting the pyrethroid insecticide standard solutions with different concentrations prepared in the step (1), hatching for 10min, taking out, and washing for 3 times by using deionized water;
(3) drawing a working curve: taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, forming a three-electrode system with the modified working electrode in the step (2), connecting the three-electrode system with an electrochemical workstation, and sequentially adding 15mL phosphate buffer solution PBS into an electrolytic bath; detecting a current response of the assembled working electrode by Differential Pulse Voltammetry (DPV); the response current intensity of the blank sample is recordedI 0The response current intensity of the pyrethroid insecticide standard solution with different concentrations is recorded asI iThe difference in response to the decrease in current intensity is ΔI = I 0-I i，ΔIMass concentration of the pyrethroid pesticide and standard solutionCWith a linear relationship therebetween, plotting ΔI－CA working curve; the concentration of the phosphate buffer solution PBS is 10mmol/L, pH, and the value is 7.4; the parameters during DPV detection are set as follows: the range and the direction are 0-1V, the step is 0.05V, the pulse time is 0.05s, the sampling time is 0.016s, and the pulse period is 0.5 s;
(4) detecting pyrethroid insecticides in a sample to be detected: replacing the standard solution of the pyrethroid insecticide in the step (1) with a sample to be detected, detecting according to the methods in the steps (2) and (3), and detecting according to the difference delta of the reduction of the response current intensityIAnd obtaining the content of the pyrethroid insecticides in the sample to be detected according to the working curve.
7. The pyrethroid insecticide of the technical scheme 1-6 is one of the following pyrethroid insecticides: permethrin, tetramethrin, cypermethrin, deltamethrin, d-trans-allethrin.
Advantageous results of the invention
(1) The pyrethroid insecticide electrochemical sensing electrode is simple to prepare, convenient to operate, low in cost, applicable to portable detection and promising in market development prospect, and realizes quick, sensitive and high-selectivity detection on a sample;
(2) according to the invention, the molecularly imprinted polymer is grown in situ on the FeCo bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray for the first time, on one hand, more and more uniform molecularly imprinted polymers can be grown by utilizing the large specific surface area of the FeCo LDH-nanoarray, and the FeCo LDH-nanoarray has excellent electron transfer capacity, so that the detection sensitivity is greatly improved; on the other hand, when dopamine is polymerized on the iron-cobalt double-metal layered hydroxide nanosheet array in situ, cobalt ions are creatively doped as an electronic mediator, and electrochemical response current is directly generated during detection, so that the sensor can directly detect in a buffer solution without adding other mediator substances, thereby further reducing the signal background, improving the detection sensitivity, greatly reducing the detection cost and reducing the environmental pollution;
(3) according to the invention, the dopamine is combined with the high-activity hydroxyl functional group rich in the iron-cobalt double-metal layered hydroxide nanosheet array and the large specific surface area, so that when dopamine is polymerized in situ on the surface of the iron-cobalt double-metal layered hydroxide nanosheet array, a thin enough polydopamine film is formed and simultaneously the polydopamine film is uniformly covered on the iron-cobalt double-metal layered hydroxide nanosheet array, thereby laying a better cushion for more and better polymerized molecularly imprinted polymers in the next step; then utilizing strong connection effect of polydopamine on hydroxyl functional groups and amino groups rich in the molecularly imprinted polymer, skillfully using FeCo LDH-nanoarray as a stirrer, immersing and stirring in the molecularly imprinted precursor mixed solution, and directly growing the molecularly imprinted polymer capable of controlling the film thickness on the surface of the FeCo LDH-nanoarray in situ by controlling the stirring speed, the dropping speed of a polymerization reaction initiator and the polymerization reaction temperature, so that the FeCo LDH-nanoarray can firmly load the molecularly imprinted polymer on one hand, and the stability and the reproducibility of the prepared electrochemical sensor are obviously improved; on the other hand, the film forming thickness of the molecularly imprinted polymer on the surface of the electrode can be effectively controlled, and the technical problem of poor reproducibility caused by the fact that the film forming thickness of the molecularly imprinted film on the surface of the electrode cannot be controlled is solved; in addition, the preparation method of the invention has important scientific significance and application value for effectively controlling the thickness of the formed film and coating the electronic mediator in situ, and fully improving the sensitivity and detection limit of the electrochemical sensor based on the molecular imprinting.
Detailed Description
Example 1 preparation of FeCo LDH-nanoarray
(1) Carrying out ultrasonic cleaning treatment on the disposable throwable electrode by respectively using dilute hydrochloric acid, absolute ethyl alcohol and deionized water so as to remove an oxide layer and surface impurities of the disposable throwable electrode;
(2) 1mmol of Fe (NO) was weighed3)3And Co (NO)3)2And 3mmol of urea CO (NH)2)2Put it into a 50mL beaker, add 30mL deionized water, stir until clear, then transfer to 50mL in a polytetrafluoroethylene reaction kettle;
(3) putting the disposable throwable electrode processed in the step (1) into the solution in the reaction kettle in the step (2), and reacting at the temperature of 100 ℃ for 12 hours to prepare a precursor electrode of the Fe-Co bimetal layered hydroxide nanosheet array;
(4) inserting the precursor electrode of the FeCo bimetal layered hydroxide nanosheet array obtained in the step (3) into phosphate buffer solution PBS containing dopamine, ammonium persulfate and cobalt nitrate, reacting for 4 hours at the temperature of 20 ℃, taking out and washing with deionized water for 2 times to prepare a FeCo bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray;
wherein the disposable throwable electrode is foamed nickel; said Fe (NO)3)3And Co (NO)3)2In a mixture of 1: 1; the concentration of dopamine is 2 mg/mL, the concentration of ammonium persulfate is 3 mg/mL, the concentration of cobalt nitrate is 0.1 mg/mL, the concentration of phosphate buffer solution PBS is 0.1mol/L, and the pH value is 7.2.
Example 2 preparation of FeCo LDH-nanoarray
(1) Carrying out ultrasonic cleaning treatment on the disposable throwable electrode by respectively using dilute hydrochloric acid, absolute ethyl alcohol and deionized water so as to remove an oxide layer and surface impurities of the disposable throwable electrode;
(2) weighing 2 mmol Fe (NO)3)3And Co (NO)3)2And 6 mmol of urea CO (NH)2)2Placing the mixture into a 50mL beaker, adding 30mL deionized water, stirring until the mixture is clear, and then transferring the mixture into a 50mL polytetrafluoroethylene reaction kettle;
(3) putting the disposable throwable electrode processed in the step (1) into the solution in the reaction kettle in the step (2), and reacting for 11 hours at the temperature of 110 ℃ to prepare a precursor electrode of the Fe-Co bimetal layered hydroxide nanosheet array;
(4) inserting the precursor electrode of the FeCo bimetal layered hydroxide nanosheet array obtained in the step (3) into phosphate buffer solution PBS containing dopamine, ammonium persulfate and cobalt nitrate, reacting for 5 hours at the temperature of 30 ℃, taking out and washing with deionized water for 3 times to prepare a FeCo bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray;
wherein the disposable throwable electrode is a pure copper sheet; said Fe (NO)3)3And Co (NO)3)2In a mixture of 1: 1; the concentration of dopamine is 3.5 mg/mL, the concentration of ammonium persulfate is 6.2 mg/mL, the concentration of cobalt nitrate is 0.3 mg/mL, the concentration of phosphate buffer solution PBS is 0.1mol/L, and the pH value is 8.0.
Example 3 preparation of FeCo LDH-nanoarray
(1) Carrying out ultrasonic cleaning treatment on the disposable throwable electrode by respectively using dilute hydrochloric acid, absolute ethyl alcohol and deionized water so as to remove an oxide layer and surface impurities of the disposable throwable electrode;
(2) 3mmol of Fe (NO) are weighed3)3And Co (NO)3)2And 9mmol of urea CO (NH)2)2Placing the mixture into a 50mL beaker, adding 30mL deionized water, stirring until the mixture is clear, and then transferring the mixture into a 50mL polytetrafluoroethylene reaction kettle;
(3) putting the disposable throwable electrode processed in the step (1) into the solution in the reaction kettle in the step (2), and reacting at the temperature of 130 ℃ for 9 hours to prepare a precursor electrode of the Fe-Co bimetal layered hydroxide nanosheet array;
(4) inserting the precursor electrode of the FeCo bimetal layered hydroxide nanosheet array obtained in the step (3) into phosphate buffer solution PBS containing dopamine, ammonium persulfate and cobalt nitrate, reacting for 6 hours at the temperature of 40 ℃, taking out and washing with deionized water for 4 times to prepare a FeCo bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray;
wherein the disposable throwable electrode is a conductive carbon cloth; said Fe (NO)3)3And Co (NO)3)2In a mixture of 1: 1; the concentration of dopamine is 5mg/mL, the concentration of ammonium persulfate is 8mg/mL, and the concentration of cobalt nitrateThe concentration is 0.5 mg/mL, the concentration of phosphate buffer solution PBS is 0.1mol/L, and the pH value is 8.5.
Example 4 preparation method of pyrethroid insecticide electrochemical sensing electrode
(1) Respectively weighing 0.25 mmol of template molecules and 3mmol of 2-methacrylic acid MAA in an ampoule bottle, adding 8 mL of acetonitrile, and performing ultrasonic treatment for 30min until all the template molecules and the 3mmol of 2-methacrylic acid MAA are dissolved;
(2) adding 15 mmol of ethylene glycol dimethacrylate EDMA into the solution obtained in the step (1), and carrying out ultrasonic treatment for 30min until the mixture is uniformly mixed to obtain a precursor mixed solution;
(3) FeCo LDH-nanoarray prepared in example 1 was clamped to a rotary stirrer, inserted into the precursor mixed solution in step (2), and subjected to N2Under the temperature of environment and water bath 20 ℃, stirring in a rotating way at the speed of 200 r/s, and simultaneously dripping 1mmol of azobisisobutyronitrile AIBN into the mixed solution at the speed of 1 d/s to initiate polymerization to obtain the in-situ grown MIP containing the template molecularly imprinted polymer on FeCo LDH-nanoarray;
(4) immersing the MIP which is obtained in the step (3) and grows in situ on FeCo LDH-nanoarray and contains the template molecularly imprinted polymer in an eluant, eluting the template molecules for 5 min at room temperature, and then taking out to obtain the NIP which is the template-free molecularly imprinted polymer; continuously washing with deionized water for 2 times, and air drying at room temperature to obtain pyrethrin pesticide electrochemical sensing electrode;
the eluent is a mixed solution of formic acid and methanol, wherein the volume ratio of the formic acid to the methanol is 9: 1.
EXAMPLE 5 preparation method of pyrethroid insecticide electrochemical sensing electrode
(1) Respectively weighing 0.35mmol of template molecules and 4 mmol of 2-methacrylic acid MAA in an ampoule bottle, adding 12 mL of acetonitrile, and carrying out ultrasonic treatment for 30min until all the template molecules and the 2-methacrylic acid MAA are dissolved;
(2) adding 18 mmol of ethylene glycol dimethacrylate EDMA into the solution obtained in the step (1), and carrying out ultrasonic treatment for 30min until the mixture is uniformly mixed to obtain a precursor mixed solution;
(3) FeCo LDH-nanoarray prepared in the technical scheme 2Clamping the mixture on a rotary stirrer, inserting the mixture into the precursor mixed solution in the step (2), and adding the mixture into a reactor to obtain a solution N2Under the temperature of environment and water bath 30 ℃, stirring in a rotating way at the speed of 60 r/s, and simultaneously dripping 1mmol of azobisisobutyronitrile AIBN into the mixed solution at the speed of 10 s/s to initiate polymerization to obtain the in-situ grown MIP containing the template molecularly imprinted polymer on FeCo LDH-nanoarray;
(4) immersing the MIP which is obtained in the step (3) and grows in situ on FeCo LDH-nanoarray and contains the template molecularly imprinted polymer in an eluant, eluting the template molecule for 10min at room temperature, and then taking out to obtain the NIP which is the template-free molecularly imprinted polymer; continuously washing with deionized water for 3 times, and air drying at room temperature to obtain pyrethrin pesticide electrochemical sensing electrode;
the eluent is a mixed solution of formic acid and methanol, wherein the volume ratio of the formic acid to the methanol is 9: 3.
Example 6 preparation method of pyrethroid insecticide electrochemical sensing electrode
(1) Respectively weighing 0.45mmol of template molecules and 5mmol of 2-methacrylic acid MAA in an ampoule bottle, adding 15mL of acetonitrile, and carrying out ultrasonic treatment for 30min until all the template molecules and the 5mmol of 2-methacrylic acid MAA are dissolved;
(2) adding 25mmol of ethylene glycol dimethacrylate EDMA into the solution obtained in the step (1), and carrying out ultrasonic treatment for 30min until the mixture is uniformly mixed to obtain a precursor mixed solution;
(3) clamping FeCo LDH-nanoarray prepared in the technical scheme 2 onto a rotary stirrer, inserting the FeCo LDH-nanoarray into the precursor mixed solution in the step (2), and adding N2Under the temperature of environment and water bath 40 ℃, rotationally stirring at the speed of 5 r/s, simultaneously dripping 1mmol of azobisisobutyronitrile AIBN into the mixed solution at the speed of 20 s/s to initiate polymerization, and obtaining the in-situ grown MIP containing the template molecularly imprinted polymer on FeCo LDH-nanoarray;
(4) immersing the MIP which is obtained in the step (3) and grows in situ on FeCo LDH-nanoarray and contains the template molecularly imprinted polymer in an eluant, eluting the template molecule for 20min at room temperature, and then taking out to obtain the NIP which is the template-free molecularly imprinted polymer; continuously washing with deionized water for 4 times, and air drying at room temperature to obtain pyrethrin pesticide electrochemical sensing electrode;
the eluent is a mixed solution of formic acid and methanol, wherein the volume ratio of the formic acid to the methanol is 9: 5.
Embodiment 7 the electrochemical sensing electrode for pyrethroid insecticides prepared in embodiments 1 to 6 is applied to detection of pyrethroid insecticides, and comprises the following steps:
(1) preparing a standard solution: preparing a group of pyrethroid insecticide standard solutions with different concentrations including blank samples;
(2) modification of a working electrode: taking the electrochemical sensing electrode of the pyrethroid insecticide as a working electrode, inserting the pyrethroid insecticide standard solutions with different concentrations prepared in the step (1), hatching for 10min, taking out, and washing for 3 times by using deionized water;
(3) drawing a working curve: taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, forming a three-electrode system with the modified working electrode in the step (2), connecting the three-electrode system with an electrochemical workstation, and sequentially adding 15mL PBS into an electrolytic bath; detecting a current response of the assembled working electrode by Differential Pulse Voltammetry (DPV); the response current intensity of the blank sample is recordedI 0The response current intensity of the pyrethroid insecticide standard solution with different concentrations is recorded asI iThe difference in response to the decrease in current intensity is ΔI = I 0-I i，ΔIMass concentration of the pyrethroid pesticide and standard solutionCWith a linear relationship therebetween, plotting ΔI－CA working curve; the PBS is 10mmol/L phosphate buffer solution, and the pH value of the phosphate buffer solution is 7.4; the parameters during DPV detection are set as follows: the range and the direction are 0-1V, the step is 0.05V, the pulse time is 0.05s, the sampling time is 0.016s, and the pulse period is 0.5 s;
(4) detecting pyrethroid insecticides in a sample to be detected: replacing the pyrethroid insecticide standard solution in the step (1) with a sample to be detected, detecting according to the methods in the steps (2) and (3), and detecting according to the reduction of the response current intensityLow difference value deltaIAnd obtaining the content of the pyrethroid insecticides in the sample to be detected according to the working curve.
Example 8 the electrochemical sensing electrode of pyrethroid insecticides prepared in examples 1-6 were applied to the detection of different pyrethroid insecticides according to the detection procedure of example 7, and the linear range and detection limit are shown in table 1:
TABLE 1 detection technical index of pyrethrin insecticides
Figure 884145DEST_PATH_IMAGE001
Example 9 detection of pyrethroid insecticides in Water sample
Accurately transferring a certain water sample, adding a pyrethroid insecticide standard solution with a certain mass concentration, taking the water sample without pyrethroid insecticides as a blank, performing a standard recovery experiment, detecting the pyrethroid insecticide electrochemical sensing electrode prepared in the embodiment 1-6 according to the steps of the embodiment 7, and determining the recovery rate of the pyrethroid insecticides in the water sample, wherein the detection result is shown in a table 2:
TABLE 2 detection results of pyrethroid insecticides in water sample
Figure 748196DEST_PATH_IMAGE002
The detection results in table 2 show that the Relative Standard Deviation (RSD) of the results is less than 3.2%, the average recovery rate is 99.0-100.4%, and the method can be used for detecting multiple pyrethroid insecticides in a water sample, and is high in sensitivity, strong in specificity, and accurate and reliable in result.

Claims (7)

1. The preparation method of the pyrethroid insecticide electrochemical sensing electrode is characterized in that the pyrethroid insecticide electrochemical sensing electrode is obtained by in-situ growth of a template-free molecularly imprinted polymer NIP on an iron-cobalt bimetallic layered hydroxide nanosheet array electrode FeCo LDH-nanoarray; the template-free molecularly imprinted polymer NIP is a molecularly imprinted polymer without template molecules; the molecularly imprinted polymer without the template molecule is obtained by eluting the template molecule from a MIP containing the template molecularly imprinted polymer; the MIP containing the template molecule engram polymer is the MIP containing the template molecule; the template molecule is a pyrethroid insecticide; the MIP containing the template molecular imprinting polymer is directly grown on FeCo LDH-nanoarray in situ, and the preparation method comprises the following preparation steps:
(1) respectively weighing 0.25-0.45 mmol of template molecules and 3-5 mmol of 2-methacrylic acid MAA in an ampoule bottle, adding 8-15 mL of acetonitrile, and carrying out ultrasonic treatment for 30min until all the template molecules and the 2-methacrylic acid MAA are dissolved;
(2) adding 15-25 mmol of ethylene glycol dimethacrylate EDMA into the solution obtained in the step (1), and carrying out ultrasonic treatment for 30min until the mixture is uniformly mixed to obtain a precursor mixed solution;
(3) clamping FeCo LDH-nanoarray on a rotary stirrer, inserting the FeCo LDH-nanoarray into the precursor mixed solution in the step (2), and adding N2And (2) rotationally stirring at the speed of 5-200 r/s in the environment and the temperature of 20-40 ℃ in a water bath, and simultaneously dropwise adding 1mmol of azobisisobutyronitrile AIBN into the mixed solution at the speed of 1-20 d/s to initiate polymerization to obtain the in-situ grown MIP on FeCo LDH-nanoarray.
2. The preparation method of the pyrethroid insecticide electrochemical sensing electrode as claimed in claim 1, wherein the preparation method of FeCo LDH-nanoarray comprises the following preparation steps:
(1) carrying out ultrasonic cleaning treatment on the disposable throwable electrode by respectively using dilute hydrochloric acid, absolute ethyl alcohol and deionized water so as to remove an oxide layer and surface impurities of the disposable throwable electrode;
(2) weighing 1-3 mmol Fe (NO)3)3And Co (NO)3)2And 3 to 9mmol of urea CO (NH)2)2Placing the mixture into a 50mL beaker, adding 30mL deionized water, stirring until the mixture is clear, and then transferring the mixture into a 50mL polytetrafluoroethylene reaction kettle;
(3) putting the disposable throwable electrode processed in the step (1) into the solution in the reaction kettle in the step (2), and reacting at the temperature of 100-130 ℃ for 9-12 hours to prepare a precursor electrode of the Fe-Co bimetal layered hydroxide nanosheet array;
(4) inserting the precursor electrode of the iron-cobalt bimetal layered hydroxide nanosheet array obtained in the step (3) into phosphate buffer solution PBS containing dopamine and ammonium persulfate, reacting for 4-6 hours at the temperature of 20-40 ℃, taking out and washing with deionized water for 2-4 times to prepare an iron-cobalt bimetal layered hydroxide nanosheet array electrode FeCo LDH-nanoarray;
the disposable and disposable electrode is selected from one of the following electrodes: foam nickel, foam copper, pure nickel sheets, pure copper sheets, pure cobalt sheets, pure silicon sheets and conductive carbon cloth; said Fe (NO)3)3And Co (NO)3)2In a mixture of 1: 1;
in phosphate buffer solution PBS containing dopamine and ammonium persulfate: the concentration of dopamine is 2-5 mg/mL, the concentration of ammonium persulfate is 3-8 mg/mL, the concentration of phosphate buffer solution PBS is 0.1mol/L, and the pH value is 7.2-8.5.
3. The preparation method of the pyrethroid insecticide electrochemical sensing electrode of claim 1, wherein the preparation steps of the template-free molecularly imprinted polymer NIP are as follows: immersing the obtained MIP which grows in situ on FeCo LDH-nanoarray and contains the template molecularly imprinted polymer in an eluant, eluting the template molecules for 5-20 min at room temperature, and then taking out to obtain the NIP which is the template-free molecularly imprinted polymer; the eluent is a mixed solution of formic acid and methanol, wherein the volume ratio of the formic acid to the methanol is 9 (1-5).
4. The preparation method of the pyrethroid insecticide electrochemical sensing electrode of claim 1, wherein the preparation steps of the pyrethroid insecticide electrochemical sensing electrode are as follows: and (3) washing the obtained template-free molecularly imprinted polymer NIP growing in situ on FeCo LDH-nanoarray with deionized water for 2-4 times, and airing at room temperature to obtain the pyrethroid insecticide electrochemical sensing electrode.
5. The method for preparing the pyrethroid insecticide electrochemical sensing electrode as claimed in any one of claims 1 to 4, wherein the pyrethroid insecticide is one of the following pyrethroid insecticides: permethrin, tetramethrin, cypermethrin, deltamethrin, d-trans-allethrin.
6. The application of the electrochemical sensing electrode of the pyrethroid insecticide prepared by the preparation method according to any one of claims 1 to 5, and the prepared electrochemical sensing electrode is applied to the detection of the pyrethroid insecticide, and is characterized in that the detection steps are as follows:
(1) preparing a standard solution: preparing a group of pyrethroid insecticide standard solutions with different concentrations including blank samples;
(2) modification of a working electrode: taking the electrochemical sensing electrode of the pyrethroid insecticide as a working electrode, inserting the pyrethroid insecticide standard solutions with different concentrations prepared in the step (1), hatching for 10min, taking out, and washing for 3 times by using deionized water;
(3) drawing a working curve: taking a saturated calomel electrode as a reference electrode, taking a platinum wire electrode as a counter electrode, forming a three-electrode system with the modified working electrode in the step (2), connecting the three-electrode system with an electrochemical workstation, and sequentially adding 15mL phosphate buffer solution PBS into an electrolytic bath; detecting a current response of the assembled working electrode by Differential Pulse Voltammetry (DPV); the response current intensity of the blank sample is recorded as I0The response current intensity of the pyrethroid insecticide standard solution with different concentrations is recorded as IiThe difference of response current intensity is Δ I ═ I0-IiThe delta I and the mass concentration C of the pyrethroid insecticide standard solution form a linear relation, and a delta I-C working curve is drawn; the concentration of the phosphate buffer solution PBS is 10mmol/L, and the pH value is 7.4; the parameters during DPV detection are set as follows: the range and the direction are 0-1V, the step is 0.05V, the pulse time is 0.05s, the sampling time is 0.016s, and the pulse period is 0.5 s;
(4) detecting pyrethroid insecticides in a sample to be detected: and (3) replacing the standard solution of the pyrethroid insecticides in the step (1) with a sample to be detected, detecting according to the methods in the steps (2) and (3), and obtaining the content of the pyrethroid insecticides in the sample to be detected according to the difference value delta I of the reduction of the response current intensity and the working curve.
7. The use of claim 6, wherein the pyrethroid insecticide is one of the following pyrethroid insecticides: permethrin, tetramethrin, cypermethrin, deltamethrin, d-trans-allethrin.
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