Preparation method and detection method of new electrochemical sensor for electrochemical regulation of carbaryl pesticide
The glass carbon electrode is modified through the three-electrode system and electrochemical regulation method, which solves the problem of cumbersome and unenvironmental preparation of Siviin electrochemical sensors, and achieves high-sensitivity and low-cost fast detection of Siviin.
Patent Information
- Application Number
- CN202310042485.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-01-28
- Publication Date
- 2025-04-22
- Estimated Expiration
- 2043-01-28
AI Technical Summary
The existing Siwei electrochemical sensors have problems such as cumbersome preparation steps, poor reproducibility, expensive and unenvironmental materials, and it is difficult to meet the needs of large-scale rapid testing.
A three-electrode system was adopted, using a platinum wire electrode and a silver/silver chloride electrode, and the glass carbon electrode was modified by electrochemical regulation methods, including timing potential method and cyclic voltammetry, and one- and two-step electrochemical regulation electrodes were prepared for detection of Siviin.
The high sensitivity of sivine detection is achieved, with a sensitivity of up to 4.2×103μA·μM-1·cm-2, a linear range of 0.2~30.0μM, and the preparation time is short, the cost is low, and the environmentally friendly. It can accurately detect sivine in complex solutions.
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Figure CN116008380B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of analysis and detection, and relates to a preparation method and a detection method of a novel electrochemical sensor for electrochemical regulation of carbaryl pesticide. Background Art
[0002] Carbaryl is a moderately toxic broad-spectrum carbamate insecticide that kills pests by inhibiting acetylcholinesterase (AChE) and is widely used in the production of fruit trees, vegetables, grains, medicinal materials, tea and other agricultural products. However, its wide application and long half-life also lead to residual carbaryl remaining in the soil and contaminating water sources, thereby entering animals and even humans, causing neurotoxicity and organ damage. In view of the serious environmental pollution and ecological risks that carbaryl may cause, it is very important to monitor carbaryl residues in agricultural soil, natural water sources and agricultural products. Therefore, a rapid, accurate, environmentally friendly and economical carbaryl detection method is urgently needed.
[0003] Electrochemical detection technology has the characteristics of rapid detection and high sensitivity. It is a rapid detection method with great potential and has been widely used in the detection of various pesticide residues. The working electrode is the core component in the electrochemical sensor. Therefore, the current carbaryl electrochemical sensor mainly enhances the sensitivity and specificity by modifying the working electrode with advanced materials and biomaterials. Common modification materials include various carbon-based, metal-based nanomaterials and enzymes, antibodies, aptamers, etc. The modification of these materials can provide recognition and catalytic sites on the electrode surface to improve the detection performance of carbaryl.
[0004] However, these carbaryl electrochemical sensors mainly have the following problems.
[0005] First, the preparation steps of material-modified electrodes are usually numerous and cumbersome, which not only takes a long time to prepare, but also easily leads to poor reproducibility.
[0006] Second, most modification materials, especially precious metal nanoparticles and antibodies, are relatively expensive and cannot meet the needs of large-scale cypermethrin testing.
[0007] Third, many toxic and harmful reagents are often used in the production of these advanced materials and the preparation of sensors, which do not meet the requirements of green environmental protection.
[0008] Therefore, developing low-cost, simple and rapid preparation, and environmentally friendly electrochemical sensors is an important approach and strategy for large-scale rapid detection of carbaryl.
[0009] Electrochemical regulation is a method of modifying the electrode surface and promoting the conversion of target analytes through a series of electrochemical means by applying a constant or cyclic potential in an electrolyte solution. The application of this electrochemical regulation method in improving detection results is not only simple and fast (only a few minutes) but also uses only common inorganic solutions. It is green and environmentally friendly and can be applied to large-scale rapid detection at a low cost. At the same time, the electrochemical derivatization of the target analyte using the electrochemical regulation method can greatly improve the selectivity of the sensor by utilizing the redox signal of the derivative to avoid interference from similar substances.
[0010] Therefore, the carbaryl electrochemical sensor based on the electrochemical regulation method can provide technical support for the rapid detection of carbaryl.
[0011] At present, there are no reports on the construction of carbaryl electrochemical sensors using electrochemical regulation methods. Summary of the invention
[0012] In view of this, the present invention provides a preparation method and detection method of a new electrochemically regulated electrochemical sensor for carbaryl pesticide to solve the problems in the prior art that the material-modified electrode preparation steps are cumbersome, the reproducibility is poor, the materials used are not only expensive but also contain many toxic and harmful reagents.
[0013] To solve the above problems, the technical solution adopted by the present invention is:
[0014] A method for preparing a novel electrochemical sensor for electrochemical regulation of carbaryl pesticides, characterized in that the sensor is prepared based on a three-electrode system, with a platinum wire electrode as a counter electrode and a silver / silver chloride electrode as a reference electrode.
[0015] The specific preparation method is:
[0016] The first step of electrochemical regulation: the working electrode is based on a glassy carbon electrode. First, Al 2 O 3 The powder was placed on a polishing flannel and rinsed thoroughly with deionized water. The electrode, a platinum wire electrode, and a silver / silver chloride electrode formed a three-electrode system and electrochemical regulation was performed using chronopotentiometry in 0.1 M phosphate buffer. The working electrode obtained was a one-step electrochemical regulation electrode (e-GCE CP );
[0017] The second step is electrochemical regulation: the three-electrode system after the first step of electrochemical regulation is electrochemically regulated using cyclic voltammetry in 0.1 M phosphate buffer, and then rinsed with deionized water to complete the preparation of the electrochemical sensor.
[0018] The time of the above-mentioned potential method is 20 s and the current is 0.3 mA.
[0019] The voltage of the above voltammetry method is -0.9 to 0.5 V, and the scanning rate is 0.5 V / s.
[0020] The pH value of the above phosphate buffer is 7.0.
[0021] The method for determining carbaryl by electrochemically regulating an electrochemical sensor is characterized in that the method steps are as follows:
[0022] The prepared sensor detects carbaryl through an electrochemical regulation strategy. The prepared electrochemical sensor is first incubated in a 0.1M PBS solution containing an unknown concentration of carbaryl at room temperature for 2 minutes, and then differential pulse voltammetry is used in the solution at a potential of 0.8 to -0.4V to obtain the relationship curve between potential and current.
[0023] The voltage range of the above voltammetry method is 0.8 to -0.4 V, the amplitude is 0.05 V, the pulse time is 0.05 s, the sampling interval is 0.0167 s, and the pulse interval is 0.5 s.
[0024] The beneficial effects of the present invention are:
[0025] 1) The sensitivity of the electrochemical sensor prepared by the preparation method of the present invention to the detection of carbaryl is as high as 4.2×10 3 μA·μM -1 cm -2 , the linear range is 0.2~30.0μM;
[0026] 2) The present invention utilizes an electrochemical control method to derivatize the analyte so as to have good selectivity among similar amino acid formate pesticides, and the sensor is prepared using only phosphate buffer, and the preparation time can be achieved within 5 minutes.
[0027] 3) The raw materials used in the preparation method of the present invention are cheap and easy to purchase, and no other toxic or harmful substances are used, thus protecting the ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 The bare glassy carbon electrode and the electrode that has only been subjected to one-step electrochemical regulation treatment in the present invention (referred to as e-GCE according to different electrochemical regulation modes) are respectively CV 、e-GCE CA 、e-GCE CP ) as the working electrode of the electrochemical sensor detecting the differential pulse voltammetry (DPV) curve of 50 μM carbaryl hydrolysis product.
[0029] Figure 2The X-ray photoelectron spectroscopy C1s deconvolution spectra of the bare glassy carbon electrode and the electrode treated by electrochemical regulation of the present invention, wherein (a) is the spectrum of the bare glassy carbon electrode; (b) is the spectrum of the e-GCE CV Spectrum; (c) e-GCE CA Spectrum; (d) e-GCE CP 's graph.
[0030] Figure 3 The bare glassy carbon electrode and the electrode treated with two-step electrochemical regulation (referred to as e-GCE according to the different electrochemical regulation modes) CP-CV 、e-GCE CP-CA 、e-GCE CP-CP ) is the effect of the electrochemical sensor of the working electrode on the detection of carbaryl hydrolysis products and the mode and parameters in the second step of electrochemical regulation. (a) is the DPV curve of each electrode detecting 50μM carbaryl hydrolysis products; (b) is the effect of the cyclic voltammetry implementation potential on the peak current of carbaryl detection in the second step of electrochemical regulation; (c) is the effect of the number of cyclic voltammetry implementation stages on the peak current of carbaryl detection in the second step of electrochemical regulation.
[0031] Figure 4 The bare glassy carbon electrode and the electrode treated with one-step or two-step electrochemical regulation (referred to as e-GCE according to the different electrochemical regulation processes) CP 、e-GCE CP-CV )’s Raman spectrum.
[0032] Figure 5 The bare glassy carbon electrode and the electrode treated with one-step or two-step electrochemical regulation (referred to as e-GCE according to the different electrochemical regulation processes) CP 、e-GCE CP-CV ) of the X-ray photoelectron spectroscopy C1s deconvolution spectrum, where (a) is the spectrum of the bare glassy carbon electrode; (b) is the spectrum of the e-GCE CP ; (c) is the spectrum of e-GCE CP-CV 's graph.
[0033] Figure 6 The DPV curves of the electrochemical regulation process and the detection selectivity of 50 μM carbaryl and other carbamate pesticide hydrolysis products. (a) is the electrode (e-GCE) treated with two-step electrochemical regulation. CP-CV ) as the working electrode of the electrochemical sensor at different potentials in 0.1M PBS and 50μM carbaryl hydrolyzate; (b) with e-GCE CP-CV PDV curves of the electrochemical sensor with the working electrode detecting 10 μM hydrolyzate of four carbamate pesticides (carbaryl, fenbucarb, isoprocarb and mefenamic acid).
[0034] Figure 7 The reaction mechanism of carbaryl during the detection process on the electrochemically regulated electrochemical sensor.
[0035] Figure 8 The electrochemical sensor was used to detect the peak current of 10 μM carbaryl hydrolyzate in the presence of equal concentrations of interfering substances (other carbamate pesticides, anions, cations, fatty acids) for electrochemical regulation.
[0036] Fig. 9 The standard curve of the electrochemical sensor for detecting carbaryl hydrolyzate by the electrochemical control of the present invention is shown in Figure 1. (a) is the DPV curve of carbaryl hydrolyzate and the linear relationship between the peak current and the concentration; (b) is the DPV curve of carbaryl hydrolyzate at low concentration (0.2-1.0 μM) and the linear relationship between the peak current and the concentration. DETAILED DESCRIPTION
[0037] This sensor is prepared based on a three-electrode system, that is, a platinum wire electrode is used as a counter electrode, a silver / silver chloride electrode is used as a reference electrode, and a modified electrode prepared in this scheme is used as a working electrode. The three-electrode system is immersed in a solution, and electrochemical regulation and subsequent detection are performed through an electrochemical workstation.
[0038] The present invention discloses a method for preparing a novel electrochemical sensor for electrochemical regulation of carbaryl pesticide. The sensor is prepared by two steps of electrochemical regulation:
[0039] The first step of electrochemical regulation: the working electrode is based on a glassy carbon electrode. First, Al 2 O 3 The powder was polished on a polishing flannel and rinsed thoroughly with deionized water. The electrode, a platinum wire electrode and a silver / silver chloride electrode formed a three-electrode system and electrochemically regulated using chronopotentiometry (0.3 mA, 20 s) in 0.1 M phosphate buffer (PBS, pH = 7.0), where the working electrode obtained was a one-step electrochemical regulation electrode (e-GCE CP );
[0040] The second step of electrochemical regulation: the three-electrode system after the first step of electrochemical regulation is subjected to electrochemical regulation using cyclic voltammetry (-0.9~0.5V, 0.5V / s) in 0.1M PBS, and then rinsed with deionized water. The three-electrode system after two steps of electrochemical regulation is the prepared electrochemical regulation electrochemical sensor. The working electrode is the two-step electrochemical regulation electrode (e-GCE CP-CV ).
[0041] Electrochemically controlled electrochemical sensor method for determining carbaryl:
[0042] The prepared electrochemical sensor was first incubated at room temperature for 2 minutes in a 0.1M PBS solution containing an unknown concentration of carbaryl to be measured, and then the differential pulse voltammetry (voltage range of 0.8-0V, amplitude of 0.05V, pulse time of 0.05s, sampling interval of 0.0167s, pulse interval of 0.5s) was used in the solution at a potential of 0.8-0.4V to obtain a curve of the relationship between potential and current. The curve will have a current peak at a potential of -0.17V, and the current difference between the current peak vertex and the background baseline is taken as the peak height. The peak height is linearly related to the content of carbaryl in the measured solution. The higher the concentration of carbaryl in the sample, the higher the peak height. The peak height of the measured peak of carbaryl standards of different concentrations was linearly fitted by the external standard method to obtain the relationship between the peak value and the concentration, and the test peak height of the unknown carbaryl sample was substituted into the concentration of carbaryl pesticide in the sample.
[0043] The present invention is further described in detail below in conjunction with the accompanying drawings:
[0044] 1. The bare glassy carbon electrode and the electrode treated by electrochemical control of the present invention (referred to as e-GCE according to different electrochemical control modes) are now used. CV 、e-GCE CA 、e-GCE CP ) is the working electrode of the electrochemical sensor detecting the differential pulse voltammetry of 50 μM carbaryl hydrolysis products.
[0045] In the figure, each electrode shows an irreversible reduction peak at -0.17V, which is determined to be the characteristic peak of carbaryl. The peak current values of the electrodes that have been electrochemically regulated are higher than those of the bare glassy carbon electrode and are similar. The solid line represents the electrode that has been subjected to the second step of electrochemical regulation (cyclic voltammetry, CV). CV 、e-GCE CA 、e-GCE CP ) after the second step of electrochemical regulation, the peak current increased to 5, 61 and 81 μA, respectively. The chronopotentiometry (CP) and chronoamperometry (CA) were very sensitive to the second step of electrochemical regulation, and the peak current increased by more than ten times. CV The change is not significant, such as Figure 1 shown.
[0046] Therefore, electrochemical regulation can modify the surface of glassy carbon electrodes, and different electrochemical regulation methods are significantly different. At the same time, multi-step electrochemical regulation strategies can have a very significant effect, which can increase the characteristic peak-to-peak current by 100 times compared with the bare electrode.
[0047] 2. To demonstrate the effect of electrochemical regulation on the surface modification of the working electrode, bare glassy carbon electrode and e-GCE CV 、e-GCECA 、e-GCE CP X-ray photoelectron spectroscopy was carried out.
[0048] It was found that different electrochemical control modes had different effects, such as Figure 2 As shown in the figure, the CV mode reduces the surface oxygen content, while the CP and CA modes significantly increase the oxygen content, because the oxygen-containing functional groups on the electrode surface will be changed during the electrochemical regulation process, and different electrochemical regulation modes and parameters can make different adjustments to the oxygen-containing functional groups. On the other hand, electrochemical regulation also changes the surface carbon hybridization type. The electrochemical regulation of the CA and CP modes will change the sp 3 Carbon is converted to sp 2 Carbon, which is directly related to the surface structure morphology of the electrode.
[0049] Therefore, electrochemical regulation can adjust the composition of oxygen-containing groups on the surface of the glassy carbon electrode and change the surface carbon hybridization type, and different electrochemical regulation modes have different effects on the surface structure.
[0050] 3. In the first step of electrochemical regulation, the CP mode was selected, and the mode of the second step of electrochemical regulation was selected, and experiments were conducted on the effects of different modes and parameters on peak current.
[0051] exist Figure 3 (a) shows that e-GCE CP The performance of the second-step electrochemical regulation in different modes is different. CA and CP electrochemical regulation basically do not change the peak current, while CV electrochemical regulation shows a very significant effect, which proves the effectiveness of multi-step electrochemical regulation and the important influence of electrochemical regulation mode. Figure 3 (b) and (c) are the effects of the parameters on the peak current in the second-step electrochemical control CV mode. It can be seen that only a small change in potential will lead to a huge difference in the results. At the same time, one stage of CV can control the electrode to increase the peak current signal by more than 10 times.
[0052] Therefore, electrochemical regulation can greatly change the electrode performance through a short period of electrochemical treatment. Slight changes in its mode and parameters also have a greater impact, and better results can be achieved through multi-step electrochemical regulation.
[0053] 4. Through bare glassy carbon electrode, one-step electrochemical control electrode (e-GCE CP ) and two-step electrochemical control electrode (e-GCE CP-CV ) to demonstrate the direct effect of multi-step electrochemical regulation on the carbon structure of the electrode surface.
[0054] Figure 4 Middle 1355cm -1 (D peak) and 1595cm -1(G peak) is the characteristic peak of carbon materials. The area ratio of the two peaks can be used to infer the structural order of the electrode surface. 2 For hybrid amorphous carbon, the larger the peak intensity ratio I(D) / I(G), the more ordered the surface is. Therefore, after the first step of CP electrochemical regulation, the ratio dropped to 1.44, indicating that the surface structure was severely damaged, and it was alleviated after the second step of CV electrochemical regulation. At the same time, the increase in the intensity of the saddle between the D and G peaks also means the generation of amorphous carbon entities, such as organic molecules, fragments, and non-graphite carbon with high density functional groups and / or defects. This further illustrates that electrochemical regulation can change the morphology of the glassy carbon electrode surface and thereby improve the electrode performance.
[0055] 5. Through bare glassy carbon electrode, one-step electrochemical control electrode (e-GCE CP ) and two-step electrochemical control electrode (e-GCE CP-CV ) was used to demonstrate the changes in oxygen-containing functional groups and carbon hybridization types on the electrode surface during the multi-step electrochemical regulation process.
[0056] After the first step of electrochemical regulation, the oxygen content on the electrode surface increased significantly, and slightly decreased after the second step of regulation, which was attributed to the change of the oxygen-containing functional groups on the surface. The C1s peak was divided into C sp by fitting. 2 , C sp 3 , CO, C=O, -COOH, we can find C sp 3 / sp 2 After the first step of CP electrochemical regulation, it decreased significantly and recovered after the second step of CV electrochemical regulation, which is related to the aromatic ring representing order and Figure 6 This is consistent with the surface ordering law caused by electrochemical regulation shown in the Raman spectrum.
[0057] Combination Figure 4 The results of Raman spectroscopy indicate that the first step, CP electrochemical regulation, strongly destroys and oxidizes the surface of the glassy carbon electrode, while the second step, CV electrochemical regulation, makes the surface structure orderly and regulates the type and content of oxygen-containing functional groups generated in the first step.
[0058] 6. Using two-step electrochemical control electrode (e-GCE CP-CV ) as the working electrode at different potentials in 0.1 M PBS and 50 μM carbaryl hydrolyzate to demonstrate the effect of electrochemical regulation, and at the same time compare the selectivity of this sensor for carbaryl compared with other similar carbamates.
[0059] This test step is carried out by electrochemical regulation. Figure 6(a) The potential of 0.8 to 0 V is the electrochemical derivatization of the test solution by electrochemical regulation. Without this step, the target quantitative peak cannot be generated in the subsequent 0 to -0.4 V. At the same time, after this step is performed in the test solution, the target quantitative peak can also be generated in the 0 to -0.4 V test in the blank solution. Therefore, the role of electrochemical regulation is to electrochemically derivatize the hydrolyzate of carbaryl and adsorb it on the surface of the working electrode. This specific electrochemical derivatization makes Figure 6 Other carbamate pesticides with similar structures in (b) will not show characteristic peaks at the same potential and thus interfere with the detection of carbaryl.
[0060] Therefore, electrochemical regulation can also electrochemically derivatize the target analytes, thereby eliminating the influence of interfering peaks generated by the redox reactions of similar substances at the same potential. The selectivity of carbaryl detection is greatly improved through an extremely simple electrochemical regulation process.
[0061] 7. Since electrochemical regulation can electrochemically derivatize the hydrolyzate of carbaryl, the reaction mechanism of the electrochemical sensor based on electrochemical regulation for detecting carbaryl was speculated.
[0062] like Figure 7 As shown, carbaryl is first hydrolyzed in alkaline solution to generate 1-naphthol before the test. 1-naphthol as a reactant is electrochemically derivatized into 1,4-naphthoquinone through electrochemical regulation at 0.8-0 V. Finally, its reduction peak (-0.17 V) is detected as a characteristic peak to detect the initial carbaryl concentration.
[0063] 8. In order to evaluate the anti-interference ability of electrochemical sensors regulated by electrochemistry, equal concentrations of interfering substances (other carbamate pesticides, anions, cations, fatty acids) were added to the 10 μM carbaryl hydrolyzate to observe the changes in the characteristic peak-to-peak current.
[0064] like Figure 8 As shown, compared with the current peak height without interference in the far left, there is no obvious change in the peak current value after adding various interferences. After testing, these substances have no significant interference with the electrochemically regulated electrochemical sensor for detecting carbaryl, indicating that the electrochemical sensor prepared by the electrochemical regulation strategy has good anti-interference ability and can accurately measure carbaryl in solutions with complex components.
[0065] 9. The performance of electrochemically regulated electrochemical sensors in detecting carbaryl was evaluated by comparing the changes in peak current when detecting different concentrations of carbaryl.
[0066] like Fig. 9 As shown in the figure, the peak current of carbaryl in the electrochemically regulated electrochemical sensor has a good linear relationship with its concentration, and the linearity can be maintained even at low concentrations ( Fig. 9(b)), so the linear range of the sensor is 0.2-30.0 μM, and the sensitivity is as high as 4.2×10 3 μA·μM -1 cm -2 , indicating that the electrochemically regulated electrochemical sensor can sensitively detect carbaryl over a wide concentration range.
Claims
1. A method for preparing a novel electrochemical sensor for electrochemical regulation of carbaryl pesticide, characterized in that: The sensor was prepared based on a three-electrode system, with a platinum wire electrode as the counter electrode and a silver / silver chloride electrode as the reference electrode; The specific preparation method is: The first step of electrochemical regulation: The working electrode is based on a glassy carbon electrode. First, Al2O3 powder is applied to a polished flannel and thoroughly rinsed with deionized water. The electrode, a platinum wire electrode, and a silver / silver chloride electrode form a three-electrode system for electrochemical regulation using chronopotentiometry in 0.1 M phosphate buffer. The resulting working electrode is a one-step electrochemical regulation electrode (e-GCE CP ); The second step is electrochemical regulation: the three-electrode system after the first step of electrochemical regulation is electrochemically regulated using cyclic voltammetry in 0.1 M phosphate buffer, and then rinsed with deionized water to complete the preparation of the electrochemical sensor.
2. The method for preparing a novel electrochemical sensor for electrochemical regulation of carbaryl pesticide according to claim 1, characterized in that: The time of the potentiometry is 20 s and the current is 0.3 mA.
3. A method for preparing a novel electrochemical sensor for electrochemical regulation of carbaryl pesticide according to claim 1 or 2, characterized in that: The voltage of the voltammetry method is -0.9 ~ 0.5 V, and the scan rate is 0.5 V / s.
4. The method for preparing a novel electrochemical sensor for electrochemical regulation of carbaryl pesticide according to claim 3, characterized in that: The pH value of the phosphate buffer is 7.0.