Flexible anti-ion interference ISO pesticide detection sensor as well as preparation method and application thereof

Abstract

The invention discloses a flexible anti-ion interference ISO pesticide detection sensor as well as a preparation method and application thereof. The sensor consists of an electrode and layered double hydroxides coated on the surface of the electrode in situ, the thickness of the layered double hydroxide is 3 to 5 nm; the strain deformation range of the sensor is-2%-2%. According to the sensor, aluminum salt and nickel salt are dissolved to obtain a mixed solution, and then the pH value of the mixed solution is adjusted to obtain a suspension; and placing the suspension and an electrode in a reaction kettle together for an in-situ hydrothermal reaction, and after the reaction is finished, cleaning and drying in sequence to obtain the composite material. Based on the excellent technical effects of the sensor, the anti-interference performance of the sensor is greatly improved on the premise of ensuring the accuracy and sensitivity of a detection result; tests show that when the sensor provided by the invention is used for inspecting ISO pesticides, R2 in an accuracy regression equation of the sensor is greater than 0.99, under the strain condition of-2% to + 2%, the electrochemical sensing performance of the sensor has no significant change, and the sensor has excellent anti-interference characteristic on metal ions such as Pd, Al and the like.

Description

Technical Field

[0001] The invention relates to a pesticide sensor, in particular to a flexible ion interference resistant ISO pesticide detection sensor and a preparation method and application thereof, belonging to the technical field of electrochemical detection. Background Art

[0002] ISO pesticide detection sensors are a class of devices specifically designed to detect and quantify pesticide residues in the environment. Pesticides are chemicals widely used in agricultural production to control pests, weeds, and other harmful organisms. However, excessive use or improper handling of pesticides can lead to environmental pollution and food safety issues. Therefore, the development of efficient and sensitive pesticide detection technology is crucial to protecting the environment and human health.

[0003] Traditional ISO pesticide detection methods are mainly divided into chromatography and immunoassay. Chromatography is a common method for detecting pesticide residues, which has high sensitivity and selectivity. Immunoassay uses the specific binding of antibodies and pesticide molecules to detect pesticide residues, which has good anti-interference. However, the above methods all require professional laboratories for testing, which is difficult to meet the needs of portable and rapid detection of pesticide residues.

[0004] In order to achieve rapid detection of pesticides in the existing technology, sensors are usually used for detection. Common sensors include electrochemical sensors, optical sensors and biosensors. Compared with traditional methods, sensor technology can achieve rapid on-site detection, reduce sample processing and analysis time, and sensors also have the advantages of low cost and can meet the requirements of large-scale applications.

[0005] However, there are still a series of problems in the application of sensor detection in pesticides, such as poor selectivity, poor stability and low sensitivity. Especially the selectivity problem, the sensor may cross-react with compounds with similar structures during the detection process, resulting in false positives, and for complex samples, especially most agricultural products, there are multiple compounds, which will interfere with the sensor's detection of specific pesticides. Summary of the invention

[0006] In view of the relationship between the existing technologies, the first purpose of the present invention is to provide a flexible ion interference resistant ISO pesticide detection sensor. The sensor is based on the synergistic effect between layered double hydroxides and electrodes, and strictly limits the deposition thickness of layered double hydroxides on electrodeposition, thereby ensuring that the sensor has excellent anti-interference characteristics while having high sensitivity; and the sensor also has a certain degree of flexibility, ensuring normal use under external stress, greatly broadening the application scenarios of the sensor.

[0007] The second object of the present invention is to provide a method for preparing a flexible ion-interference-resistant ISO pesticide detection sensor. The method controls the pH value of a mixed metal salt solution, adjusts the solution to the vicinity of a coprecipitation phase transition point, and then deposits the mixed solution in situ on an electrodeposition surface by a hydrothermal method; the method does not require high-temperature sintering, and the in-situ deposition method greatly simplifies the process flow and reduces the preparation cost while ensuring a stable combination of the two, making it suitable for large-scale industrial production.

[0008] The third object of the present invention is to provide an application of a flexible ion interference resistant ISO pesticide detection sensor for online detection of ISO pesticides. Based on the excellent technical effect of the above sensor, while ensuring the accuracy and sensitivity of the detection results, the anti-interference ability of the sensor is greatly improved; after testing, when the sensor provided by the present invention inspects ISO pesticides, the R in the accuracy regression equation is 2 >0.99, under the condition of -2% to +2% strain, its electrochemical sensing performance has no significant change, and it has excellent anti-interference characteristics for metal ions such as Pd and Al.

[0009] In order to achieve the above technical objectives, the present invention provides a flexible ion interference resistant ISO pesticide detection sensor, characterized in that: it is composed of an electrode and a layered double hydroxide in situ wrapped on its surface; the thickness of the layered double hydroxide is 3 to 5 nm; the strain range of the sensor is -2 to 2%;

[0010] As a preferred embodiment, the layered double hydroxide is at least one of NiFe-LDH, ZnAl-LDH, CoAl-LDHs, CoNiFe-LDHs and NiAl-LDH.

[0011] The present invention also provides a method for preparing a flexible ion interference resistant ISO pesticide detection sensor, the process of which is: dissolving aluminum salt and nickel salt to obtain a mixed solution, then adjusting the pH value of the mixed solution to obtain a suspension; placing the suspension and the electrode together in a reactor for an in-situ hydrothermal reaction, and after the reaction is completed, cleaning and drying in sequence to obtain the sensor.

[0012] As a preferred solution, the aluminum salt and the nickel salt have a metal ion molar ratio of 1:1 to 4.

[0013] As a preferred solution, the aluminum salt is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate.

[0014] As a preferred solution, the nickel salt is at least one of nickel nitrate, nickel chloride and nickel sulfate.

[0015] As a preferred solution, the aluminum salt and the nickel salt have a metal ion molar ratio of 1:1.

[0016] As a preferred solution, the aluminum salt is aluminum nitrate, and the nickel salt is nickel nitrate.

[0017] As a preferred solution, the pH value of the mixed solution is adjusted to 5.5-6.5 by using a caustic soda solution.

[0018] As a preferred solution, the conditions of the hydrothermal reaction are: temperature of 160-220° C. and time of 20-28 h.

[0019] As a preferred solution, the drying method is oven drying, and the conditions are: temperature of 60 to 90° C. and time of 22 to 26 hours.

[0020] The present invention also provides an application of a flexible ion interference resistant ISO pesticide detection sensor for online detection of ISO pesticides, the process of which includes:

[0021] 1) The obtained sensors were used as working electrodes in a three-electrode system according to different metal atomic ratios in the layered double hydroxide, and ISO pesticide standards were detected to screen the optimal atomic ratio sensor;

[0022] 2) Prepare a series of ISO pesticide standards according to a fixed gradient, use the optimal atomic ratio sensor as the working electrode in the three-electrode system, test the pesticide standards, and plot the test results as a standard curve;

[0023] 3) Using the optimal atomic ratio sensor as a three-electrode system to detect the sample to be tested and comparing it with the standard curve, the result is obtained;

[0024] The reference electrode in the sensor is an Ag / AgCl electrode, and the counter electrode is a carbon electrode.

[0025] As a preferred solution, the screening process of the optimal atomic ratio sensor is: placing the ISO solution in a three-electrode system for differential pulse voltammetry detection to obtain current-voltage curves of the three-electrode systems of sensors with different atomic ratios.

[0026] As a preferred solution, the process of obtaining the standard curve is: fitting the current-voltage data points using the least squares method to fit to R 2 >0.99, you get it.

[0027] 1) The sensor provided by the present invention is based on the synergistic effect between the layered double hydroxide and the electrode, and strictly limits the deposition thickness of the layered double hydroxide in the electrodeposition, thereby ensuring that the sensor has excellent anti-interference characteristics while having high sensitivity; and the sensor also has a certain flexibility, ensuring normal use under external stress, greatly broadening the application scenarios of the sensor.

[0028] 2) The preparation method provided by the present invention controls the pH value of the mixed metal salt solution, adjusts the solution to the vicinity of the co-precipitation phase transition point, and then deposits the mixed solution in situ on the electrodeposition surface by a hydrothermal method; this method does not require high-temperature sintering, and the in-situ deposition method greatly simplifies the process flow while ensuring a stable combination of the two, reduces the preparation cost, and is suitable for large-scale industrial production.

[0029] 3) The technical solution provided by the present invention is based on the excellent technical effect of the above-mentioned sensor. Under the premise of ensuring the accuracy and sensitivity of the detection results, it also greatly improves the anti-interference ability of the sensor; after testing, when the sensor provided by the present invention inspects ISO pesticides, the R in the accuracy regression equation is 2 >0.99, under the condition of -2% to +2% strain, its electrochemical sensing performance has no significant change, and it has excellent anti-interference characteristics for metal ions such as Pd and Al. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram and parameter description of the strain applied to the sensor obtained in Example 1 of the present invention;

[0031] Figure 2 This is a differential pulse voltammetry curve diagram of the NiAl-LDH sensor of various atomic ratios obtained in Example 1 of the present invention when detecting ISO pesticides;

[0032] Figure 3 This is a differential pulse voltammetry curve diagram of the optimal atomic ratio sensor obtained in Example 1 of the present invention when detecting ISO pesticides of various concentrations;

[0033] Figure 4 This is a current-concentration fitting diagram when the sensor obtained in Example 1 of the present invention detects ISO pesticides of different concentrations;

[0034] Figure 5 This is a current-interference ion differential pulse voltammetry curve of the sensor obtained in Example 1 of the present invention for detecting ISO pesticides under the interference of heavy metals and other ions;

[0035] Figure 6 This is a peak current-interference ion histogram of the sensor obtained in Example 1 of the present invention detecting ISO pesticides under the interference of heavy metals and other ions;

[0036] Figure 7 This is a differential pulse voltammetry curve diagram of a continuous experiment when the sensor obtained in Example 1 of the present invention detects ISO pesticides;

[0037] Figure 8 This is a graph showing the change in peak current versus number of times in a continuous experiment when the sensor obtained in Example 1 of the present invention detects ISO pesticides.

[0038] Fig. 9 is a linear fitting diagram of the sensor obtained in Example 1 of the present invention when detecting ISO pesticides under a strain of -1.2% to +1.2%;

[0039] Fig.10 is a graph showing the relationship between the peak current and the strain magnitude of the sensor obtained in Example 1 of the present invention when detecting ISO pesticides under a strain of -1.2% to +1.2%;

[0040] Fig.11 This is a graph showing the sensitivity change of the sensor obtained in Example 1 of the present invention when detecting ISO pesticides under a strain of -1.2% to +1.2%. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described in detail below in conjunction with the accompanying drawings and embodiments.

[0042] The flexible ion interference-resistant ISO pesticide detection sensor provided by the present invention is based on the self-oxidation-reduction process between layered double hydroxides. It has good electrochemical activity characteristics and good selective adsorption for ISO pesticides. The present invention adopts a traditional three-electrode system: an electrode modified with NiAl-LDH on the surface of a screen-printed electrode is used as a working electrode. The screen-printed electrode also includes: a reference electrode (silver) and a counter electrode. The electrochemical signal is detected by differential pulse voltammetry (DPV), and its quantitative detection is achieved based on the correlation between the current signal size and the ISO pesticide concentration.

[0043] Example 1

[0044] The specific preparation process of the ISO pesticide sensor provided by the present invention is as follows:

[0045] Aluminum nitrate and nickel nitrate are added to deionized water at a metal atomic ratio of 1:1 to obtain a mixed solution, and then 1 mol / L NaOH is slowly added to adjust the fusion pH to 6 to obtain a suspension; the suspension and the electrode are transferred to a stainless steel polytetrafluoroethylene-lined reactor, and the reactor is heated to 180°C and maintained for 24 hours for an in-situ hydrothermal reaction. After the reaction is completed, it is naturally cooled to room temperature, and the electrode is taken out, washed, and dried at 70°C for 24 hours to obtain the product.

[0046] Example 2

[0047] This embodiment is exactly the same as the embodiment 1, except that the metal atomic ratio of aluminum nitrate to nickel nitrate is 1:2.

[0048] Example 3

[0049] This embodiment is exactly the same as the embodiment 1, except that the metal atomic ratio of aluminum nitrate to nickel nitrate is 1:3.

[0050] Example 4

[0051] This embodiment is exactly the same as the embodiment 1, except that the metal atomic ratio of aluminum nitrate to nickel nitrate is 1:4.

[0052] The sensors obtained in Examples 1 to 4 were applied to ISO pesticide detection, and the process was as follows:

[0053] 1) The sensor obtained in Examples 1 to 4 was used as a working electrode, Ag / AgCl was used as a reference electrode, and a carbon electrode was used as a counter electrode to form a three-electrode system. The ISO solution was subjected to differential pulse voltammetry detection. After standing for a set time (e.g., 10 s), a set of forward scanning voltages in the voltage scanning range of 0.5 V to 0.85 V was applied to the three-electrode system. The change of current-voltage was recorded by an electrochemical workstation, and the current-voltage curves of electrochemical sensing current analysis of ISO by NiAl-LDH prepared with different atomic ratios were obtained as shown in FIG. Figure 2 ,pass Figure 2 The optimal atomic ratio of the sensor screened out is 1:4 in Example 4.

[0054] 2) Using the sensor provided in Example 4 to perform differential pulse voltammetry on a series of ISO pesticide standards to obtain a differential pulse voltammetry curve, and then using the sensor to detect pesticide samples to obtain a current-concentration fitting diagram, whose R 2 >0.99, indicating an excellent fit.

[0055] The present invention also tests the anti-interference characteristics of the sensor. The sensor obtained in Example 4 is subjected to anti-interference and repeatability experiments on ISO to obtain a peak current-voltage curve and a bar graph. The results are as follows: Figures 5 to 8 As shown, through Figures 5 to 8 It can be seen that under the interference of 8mM concentration of impurities, its current-voltage curve shows excellent stability.

[0056] Furthermore, in order to detect the anti-interference ability of the sensor of the present invention to external stress, the present invention places the sensor on a fixture that applies strain, adjusts the fixture to adjust the sensor deformation to the scale values ​​corresponding to the tensile strain of -1.2%, -0.8%, -0.4%, +0.4%, +0.8%, and +1.2%, respectively, and obtains the current-voltage curve and regression equation, such as Fig. 9 and Fig.10As shown in the figure, the error of the sensor in the strain state and the non-strain state is ≤10%, which shows excellent external stress resistance. After the external stress is removed, the sensitivity test of the sensor is performed again, and the results are as follows Fig.11 As shown, Fig.11 As shown, the device sensitivity did not change significantly after the application of tensile strain, which indicates that the sensor is extremely stable under flexible deformation.

Claims

1. A flexible ion interference resistant ISO pesticide detection sensor, characterized in that: The invention is composed of an electrode and a layered double hydroxide in situ wrapped on its surface; the thickness of the layered double hydroxide is 3-5nm; and the strain range of the sensor is -2-2%.

2. The flexible ion interference resistant ISO pesticide detection sensor according to claim 1, characterized in that: The layered double hydroxide is at least one of NiFe-LDH, ZnAl-LDH, CoAl-LDHs, CoNiFe-LDHs and NiAl-LDH.

3. The method for preparing a flexible ion interference resistant ISO pesticide detection sensor according to claim 1 or 2, characterized in that: Aluminum salt and nickel salt are dissolved to obtain a mixed solution, and then the pH value of the mixed solution is adjusted to obtain a suspension; the suspension and the electrode are placed in a reactor to perform an in-situ hydrothermal reaction, and after the reaction is completed, the mixture is cleaned and dried in sequence to obtain the mixture.

4. The method for preparing a flexible ion interference resistant ISO pesticide detection sensor according to claim 3, characterized in that: The aluminum salt and the nickel salt have a metal ion molar ratio of 1:1 to 4; the aluminum salt is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate; the nickel salt is at least one of nickel nitrate, nickel chloride and nickel sulfate.

5. The method for preparing a flexible ion interference resistant ISO pesticide detection sensor according to claim 3, characterized in that: The aluminum salt and the nickel salt have a metal ion molar ratio of 1:1; the aluminum salt is aluminum nitrate, and the nickel salt is nickel nitrate.

6. The method for preparing a flexible ion interference resistant ISO pesticide detection sensor according to claim 3, characterized in that: The pH value of the mixed solution is adjusted to 5.5-6.5 by caustic soda solution; the conditions of the hydrothermal reaction are: temperature of 160-220° C. and time of 20-28 hours.

7. The method for preparing a flexible ion interference resistant ISO pesticide detection sensor according to claim 3, characterized in that: The drying method is oven drying, and the conditions are: temperature of 60 to 90° C. and time of 22 to 26 hours.

8. Application of a flexible ion interference resistant ISO pesticide detection sensor according to claim 1 or 2, characterized in that: For online detection of ISO pesticides, the process includes: 1) The obtained sensors were used as working electrodes in a three-electrode system according to different metal atomic ratios in the layered double hydroxide, and ISO pesticide standards were detected to screen the optimal atomic ratio sensor; 2) Prepare a series of ISO pesticide standards according to a fixed gradient, use the optimal atomic ratio sensor as the working electrode in the three-electrode system, test the pesticide standards, and plot the test results as a standard curve; 3) Using the optimal atomic ratio sensor as a three-electrode system to detect the sample to be tested and comparing it with the standard curve, the result is obtained; The reference electrode in the sensor is an Ag / AgCl electrode, and the counter electrode is a carbon electrode.

9. Application of a flexible ion interference resistant ISO pesticide detection sensor according to claim 8, characterized in that: The screening process of the optimal atomic ratio sensor is as follows: placing the ISO solution in a three-electrode system for differential pulse voltammetry detection, and obtaining current-voltage curves of the three-electrode systems of sensors with different atomic ratios.

10. The application of a flexible ion interference resistant ISO pesticide detection sensor according to claim 8, characterized in that: The process of obtaining the standard curve is as follows: the current-voltage data points are fitted using the least squares method to fit to R 2 >0.99, you get it.

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