Electrochemical sensor for high-sensitivity detection of carbendazim and preparation method thereof

Abstract

The invention belongs to the field of electrochemical sensors, and relates to an electrochemical sensor for high-sensitivity detection of carbendazim and a preparation method of the electrochemical sensor. The surface of a glassy carbon electrode (GCE) is modified with an LDMS-CCN-GCT nanocomposite material prepared from dendritic large-aperture mesoporous silica, conductive carbon black nanoparticles and graphitized carbon nanotubes, and a CCN-GCT-LDMS / GCE working electrode is formed. The preparation method comprises the following steps: firstly, uniformly dispersing CCN and GCT in an N, N-dimethylformamide solution through magnetic stirring in an ultrasonic environment, wherein the CCN and the GCT are equal in mass; then, adding LDMS into the solution, and carrying out ultrasonic dispersion to obtain a uniformly mixed CCN (at) GCT (at) LDMS suspension; and finally, dispensing the uniform suspension onto the surface of GCE, and drying under an infrared lamp to prepare the working electrode CCN (at) GCT (at) LDMS / GCE modified by the CCN (at) GCT (at) LDMS nano composite material. Based on the synergistic effect generated by LDMS and CCN-coated GCT, the CCN-coated GCT-coated LDMS / GCE sensor is high in sensitivity, the detection limit can reach 7.36 nM, and the CCN-coated GCT-coated LDMS / GCE sensor has excellent carbendazim sensing detection performance.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical sensors and relates to an electrochemical sensor for highly sensitive detection of carbendazim and a preparation method thereof. Background Art

[0002] Carbendazim is a broad-spectrum fungicide that can be used for foliar spraying, seed treatment, and soil treatment, and can effectively prevent and treat a variety of crop diseases caused by fungi. In the agricultural field, carbendazim can prevent and treat gray mold of green onions and leeks, gray mold of tomatoes, cucumbers, and kidney beans, and can also prevent and treat sclerotinia of eggplants, cucumbers, cruciferous vegetables, tomatoes, lettuce, and kidney beans. The fungicide residue can cause liver disease and chromosomal aberrations and is toxic to mammals. If the human body is poisoned by mouth, symptoms such as dizziness, nausea, and vomiting will occur. It can be seen that if used improperly, carbendazim will have a serious impact on human life and health and the ecological environment.

[0003] At present, traditional carbendazim detection and analysis technologies mainly involve high performance liquid chromatography, ultraviolet spectrophotometry, gas chromatography-mass spectrometry, liquid chromatography-mass spectrometry, etc. These analytical techniques have played an important role in the detection of carbendazim. However, these analytical techniques also have some disadvantages, such as: expensive detection and analysis hardware equipment, large equipment space volume, complex specialized operation, long detection and analysis cycle, and it is difficult to achieve portable field detection of outdoor carbendazim. In contrast, the electrochemical sensor detection method has the advantages of high efficiency, sensitivity, low cost and easy miniaturization. In recent years, electrochemical sensing detection technology has gradually developed, but the electrochemical sensing detection technology for carbendazim is still immature and needs further improvement. Therefore, it is particularly urgent to develop a fast, low-cost and highly sensitive electrochemical sensor for carbendazim detection.

[0004] The Chinese invention patent (publication number: CN115524383A) provides an electrochemical sensor for highly sensitive detection of carbendazim and a detection method thereof, wherein the electrochemical sensor is composed of a glassy carbon electrode GCE surface modified with a Super P Li / ZIF-8 nanocomposite prepared from a highly conductive superconducting carbon black Super P Li and a zinc-based metal organic framework material ZIF-8. Super P Li is uniformly dispersed in a DMF solution, and then an equal amount of ZIF-8 is added to the above solution, and a uniform mixed suspension is obtained by ultrasonic dispersion. Finally, 5 μL of the above uniform suspension is drop-coated on the surface of the glassy carbon electrode and dried under an infrared lamp to obtain a working electrode modified with a Super P Li / ZIF-8 nanocomposite. The disadvantage of this method is that the Super P Li used has a branched morphology, and the conductive network formed is composed of "point-point" contact of zero-dimensional carbon nanoparticles, and there are still certain deficiencies in enhancing the charge transfer efficiency. Moreover, ZIF-8 is a metal organic framework material with a porous structure with a limited specific surface area, and there is still a lot of room for improvement in adsorption and enrichment of the detected object on the electrode surface.

[0005] The information disclosed in this background section is only intended to enhance understanding of the overall background of the invention and should not be taken as an acknowledgement or any form of suggestion that the information constitutes the prior art known to a person skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide an electrochemical sensor for highly sensitive detection of carbendazim and a preparation method thereof. The electrochemical sensor prepared by the method can effectively overcome the shortcomings of traditional detection methods, such as expensive detection and analysis hardware equipment, large equipment space volume, complex specialized operations, long detection and analysis cycle, and difficulty in realizing portable on-site detection of carbendazim outdoors. The electrochemical sensor has the advantages of low cost, high speed, high sensitivity, small space volume, easy to carry, and easy to realize portable on-site detection of carbendazim outdoors.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] The invention discloses an electrochemical sensor for highly sensitive detection of carbendazim. The LDMS@CCN@GCT nanocomposite material prepared by dendritic large-pore mesoporous silica (LDMS), conductive carbon black nanoparticles (CCN) and graphitized carbon nanotubes (GCT) is modified on the surface of a glassy carbon electrode (GCE) to form a CCN@GCT@LDMS / GCE working electrode. The CCN@GCT@LDMS / GCE working electrode, an auxiliary electrode and a reference electrode are placed in an electrolytic cell to form an electrochemical sensor for highly sensitive detection of carbendazim.

[0009] In the electrochemical sensor for highly sensitive detection of carbendazim, the content range of each component in the LDMS@CCN@GCT nanocomposite material is as follows: the mass proportion of LDMS is 30-50%, the mass proportion of CCN is 25-35%, and the mass proportion of GCT is 25-35%.

[0010] In the electrochemical sensor for highly sensitive detection of carbendazim, the thickness of the LDMS@CCN@GCT nanocomposite material on the surface of GCE is 80 to 200 μm.

[0011] The method for preparing the electrochemical sensor for highly sensitive detection of carbendazim comprises the following steps:

[0012] (1) Preparation of uniform CCN@GCT@LDMS suspension: First, equal masses of CCN and GCT were added to N,N-dimethylformamide (DMF) solution, and continuous magnetic stirring was performed under ultrasonic environment to obtain uniformly dispersed CCN@GCT suspension; then, a certain amount of LDMS was added to the above solution, and the LDMS addition ratio was 50% of the total mass of LDMS, CCN and GCT, and ultrasonic dispersion and mixing were performed again to obtain uniformly mixed CCN@GCT@LDMS suspension;

[0013] (2) Preparation of CCN@GCT@LDMS / GCE working electrode: The CCN@GCT@LDMS uniform suspension was droplet-coated onto the pre-polished GCE surface and dried under an infrared lamp to obtain a CCN@GCT@LDMS / GCE working electrode.

[0014] (3) Preparation of an electrochemical sensor for highly sensitive detection of carbendazim: Using a platinum wire electrode as an auxiliary electrode and a saturated calomel electrode as a reference electrode, the CCN@GCT@LDMS / GCE working electrode, auxiliary electrode, and reference electrode were placed in a three-electrode glass electrolytic cell to form an electrochemical sensor for highly sensitive detection of carbendazim.

[0015] Furthermore, in the step (1), the ultrasonic dispersion time is 90 to 180 minutes, and the ultrasonic power is 180W.

[0016] Furthermore, in step (2), the infrared lamp drying time is 5 to 15 minutes.

[0017] Furthermore, in step (2), in order to construct the target working electrode, the surface of the glassy carbon electrode is pretreated by wet sand grinding, and the surface of the glassy carbon electrode is polished by ultrasonic cleaning to obtain a glassy carbon electrode with a clean surface and free of impurities.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] (1) The present invention uses CCN@GCT@LDMS nanocomposite material as a sensitizer for the sensor working electrode, which can overcome the shortcomings of the conventional working electrode electrolyte having weak adsorption capacity, low charge transport efficiency, and weak enrichment capacity of carbendazim molecules on the working electrode surface.

[0020] (2) The LDMS used in the present invention is dendritic mesoporous silica. Compared with conventional mesoporous silica, dendritic mesoporous silica has a dendritic pore structure, the connectivity between the pores is more complex and rich, and the large pore size can also accommodate larger molecules or particles, with advantages such as high loading capacity and high porosity. The unique dendritic pore structure increases the internal pore connectivity and material transmission channels; the large pore size can accommodate larger molecules and larger guest molecules; the high porosity can provide a larger specific surface area and pore volume, which is conducive to the adsorption and loading of a large amount of substances; the dendritic pores and large pore size can achieve rapid diffusion and transmission of the target detection object, significantly improving the enrichment capacity of carbendazim molecules on the electrode surface.

[0021] (3) The present invention uses conductive carbon black nanoparticles (CCN) and graphitized carbon nanotubes (GCT) of equal mass to avoid the shortcomings of conductive carbon materials with a single morphology structure. Through the full contact between zero-dimensional carbon nanoparticles and one-dimensional hollow graphitized carbon nanotubes, a one-dimensional hollow graphitized carbon nanotube network is embedded in the CCN branched conductive structure, which can form an efficient, fast, interconnected and interoperable "point-line synergistic" high-conductivity charge transport pathway, which can maintain a high-speed charge conduction pathway in electrochemically active substances and enhance the charge transport efficiency.

[0022] (4) The CCN@GCT@LDMS nanocomposite material used in the present invention can fully utilize the advantages of the above two materials, exhibit a synergistic effect, and significantly improve the conductivity and carbendazim enrichment capacity of the working electrode modified coating.

[0023] (5) The sensor prepared based on the CCN@GCT@LDMS nanocomposite material of the present invention has the advantages of being simple, efficient, low-cost, highly sensitive, and easy to carry in detecting carbendazim, and can easily realize portable on-site detection of carbendazim outdoors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 CV curves of the CCN@GCT@LDMS / GCE sensor prepared in Example 1 of the present invention and the unmodified sensor for detecting carbendazim. In the figure, the abscissa E represents the potential (V vs SCE), and the ordinate I represents the current (μA).

[0025] Figure 2This is the DPV curve of carbendazim detected by the CCN@GCT@LDMS / GCE sensor prepared in Example 1 of the present invention. In the figure, the abscissa E represents the potential (V vs SCE), and the ordinate I represents the current (μA). DETAILED DESCRIPTION

[0026] In the specific implementation process, the present invention proposes an electrochemical sensor for highly sensitive detection of carbendazim and a preparation method thereof, wherein the CCN@GCT@LDMS / GCE working electrode is composed of a glassy carbon electrode (GCE) surface modified by a LDMS@CCN@GCT nanocomposite prepared by dendritic macroporous silica (LDMS), conductive carbon black nanoparticles (CCN) and graphitized carbon nanotubes (GCT). First, equal masses of CCN and GCT are uniformly dispersed in a N,N-dimethylformamide (DMF) solution by magnetic stirring under an ultrasonic environment; then, a certain amount of LDMS is added to the above solution, and a uniform suspension of the CCN@GCT@LDMS mixture is obtained by ultrasonic dispersion; finally, the uniform suspension of the CCN@GCT@LDMS mixture is drop-coated on the surface of the GCE and dried under an infrared lamp to obtain a working electrode CCN@GCT@LDMS / GCE modified by the CCN@GCT@LDMS nanocomposite.

[0027] In the present invention, the technical indicators of the conductive carbon black nanoparticles (CCN) are as follows: grain size 30-45nm, specific surface area 120-130m 2 / g. The technical indicators of graphitized carbon nanotubes (GCT) are as follows: diameter 10-20nm, length 5-30μm, purity>99.9wt%. The technical indicators of dendritic macroporous mesoporous silica (LDMS) are as follows: average particle size ~100nm, average pore size ~13nm.

[0028] The present invention is further described below with reference to specific embodiments.

[0029] Example 1

[0030] In this embodiment, a method for preparing an electrochemical sensor for highly sensitive detection of carbendazim comprises the following steps:

[0031] (1) Preparation of CCN@GCT@LDMS uniform suspension: 20 mg of CCN (10 mg) and GCT (10 mg) of equal mass were added to 10 mL of N,N-dimethylformamide (DMF) solution, and continuous magnetic stirring (180 mins) was performed under ultrasonic environment to obtain a uniformly dispersed black suspension of CCN and GCT. Subsequently, a certain amount of LDMS was added to the above solution, the amount of LDMS added was 20 mg, and ultrasonic dispersion (90 mins) was again used to mix evenly to obtain a uniformly mixed CCN@GCT@LDMS suspension.

[0032] (2) Preparation of CCN@GCT@LDMS / GCE working electrode: 5 μL of CCN@GCT@LDMS uniform suspension was dropleted onto the pre-polished and cleaned GCE surface. The shape and size of GCE were: CHI104 glassy carbon disk electrode diameter 3 mm, and dried under infrared light for 6 mins to obtain CCN@GCT@LDMS / GCE working electrode.

[0033] Among them, the thickness of LDMS@CCN@GCT nanocomposite on the GCE surface is 80 to 200 μm.

[0034] (3) Preparation of electrochemical sensor for highly sensitive detection of carbendazim: The above-mentioned CCN@GCT@LDMS / GCE working electrode, auxiliary electrode (platinum wire electrode) and reference electrode (saturated calomel electrode) were placed in a three-electrode glass electrolytic cell to form an electrochemical sensor for carbendazim detection. The detection limit can reach 7.36 nM, which has excellent electrochemical sensing detection performance for carbendazim.

[0035] The CV curves of the CCN@GCT@LDMS / GCE sensor prepared in this example and the unmodified sensor for detecting carbendazim are shown in Figure 1 The DPV curve of the prepared CCN@GCT@LDMS / GCE sensor for detecting carbendazim is shown in Figure 2 .

[0036] Depend on Figure 1It can be seen that the CV curves of these sensors detecting carbendazim all show an oxidation peak and a reduction peak. It should be noted that the CV peak current of the unmodified sensor is weak. In contrast, the CCN@GCT@LDMS / GCE sensor shows a clear CV peak, and its peak current response is significantly enhanced. It can be seen that the CCN@GCT@LDMS nanocomposite material as a working electrode sensitizer can significantly enhance the sensing detection performance of carbendazim, which is closely related to the synergistic enhancement effect of the CCN@GCT@LDMS nanocomposite material. LDMS is a dendritic mesoporous silica. Compared with conventional mesoporous silica, dendritic mesoporous silica has a dendritic pore structure, the connectivity between the pores is more complex and rich, and the large pore size can also accommodate larger molecules or particles, with the advantages of high loading capacity and high porosity. The unique dendritic pore structure increases the internal pore connectivity and material transfer channels; the large pore size can accommodate larger molecules and larger guest molecules; the high porosity can provide a large specific surface area and pore volume, which is conducive to the adsorption and loading of a large amount of substances; the dendritic pores and large pore size can achieve rapid diffusion and transmission of target detection objects, significantly improving the enrichment capacity of carbendazim molecules on the electrode surface. CCN and GCT of equal quality can avoid the shortcomings of conductive carbon materials with a single morphological structure. Through the full contact between zero-dimensional carbon nanoparticles and one-dimensional hollow graphitized carbon nanotubes, a one-dimensional hollow graphitized carbon nanotube network is embedded in the CCN branched conductive structure, which can form an efficient, fast, interconnected and interoperable "point-line synergy" highly conductive charge transport pathway, which can maintain a high-speed charge conduction pathway in electrochemically active substances and enhance charge transport efficiency.

[0037] Depend on Figure 2 It can be seen that the linear carbendazim concentration range of the DPV test of CCN@GCT@LDMS / GCE sensor for detecting carbendazim is 0.01μM to 20μM. The research results show that the carbendazim concentration has a significant effect on the peak current response of the DPV curve. With the increase of carbendazim concentration, the peak current response of the DPV curve for detecting carbendazim gradually increases, and the two show a positive correlation. Based on the fitted linear relationship between carbendazim concentration and the peak current response of the DPV curve, the linear regression equation of the response can be obtained, and then the detection limit of the prepared CCN@GCT@LDMS / GCE sensor for carbendazim is 7.36nM by calculation and analysis, indicating that the above-prepared sensor has excellent carbendazim sensing detection performance.

[0038] Example 2

[0039] In this embodiment, a method for preparing an electrochemical sensor for highly sensitive detection of carbendazim comprises the following steps:

[0040] (1) Preparation of CCN@GCT@LDMS uniform suspension: 30 mg of CCN (15 mg) and GCT (15 mg) of equal mass were added to 15 mL of N,N-dimethylformamide (DMF) solution, and continuous magnetic stirring (180 mins) was performed under ultrasonic environment to obtain a uniformly dispersed black suspension of CCN and GCT of equal mass. Subsequently, a certain amount of LDMS was added to the above solution, the amount of LDMS added was 30 mg, and ultrasonic dispersion (90 mins) was performed again to mix evenly to obtain a uniformly mixed CCN@GCT@LDMS / GCE suspension.

[0041] (2) Preparation of CCN@GCT@LDMS / GCE working electrode: 5 μL of CCN@GCT@LDMS uniform suspension was dropleted onto the pre-polished and cleaned GCE surface. The shape and size of GCE were: CHI104 glassy carbon disk electrode diameter 3 mm, and dried under infrared light for 6 mins to obtain CCN@GCT@LDMS / GCE working electrode.

[0042] Among them, the thickness of LDMS@CCN@GCT nanocomposite on the GCE surface is 80 to 200 μm.

[0043] (3) Preparation of electrochemical sensor for highly sensitive detection of carbendazim: The above-mentioned CCN@GCT@LDMS / GCE working electrode, auxiliary electrode (platinum wire electrode) and reference electrode (saturated calomel electrode) were placed in a three-electrode glass electrolytic cell to form an electrochemical sensor for carbendazim detection, which has excellent electrochemical sensing detection performance for carbendazim.

[0044] The implementation results show that the sensor prepared by the present invention has low cost, high efficiency, high sensitivity, small space occupation volume, easy to carry, and easy to realize outdoor field detection. Based on the synergistic effect of LDMS and CCN@GCT, the CCN@GCT@LDMS / GCE sensor has high sensitivity, low detection limit, and excellent carbendazim sensing detection performance.

[0045] The exemplary embodiments are chosen and described for the purpose of explaining certain principles of the invention and their practical applications, thereby enabling those skilled in the art to make and utilize various exemplary embodiments of the invention as well as various alternatives and modifications.

Claims

1. An electrochemical sensor for highly sensitive detection of carbendazim, characterized in that: LDMS@CCN@GCT nanocomposite material prepared by dendritic macroporous mesoporous silica (LDMS), conductive carbon black nanoparticles (CCN) and graphitized carbon nanotubes (GCT) was modified on the surface of glassy carbon electrode (GCE) to form CCN@GCT@LDMS / GCE working electrode. The CCN@GCT@LDMS / GCE working electrode, auxiliary electrode and reference electrode were placed in an electrolytic cell to form an electrochemical sensor for highly sensitive detection of carbendazim.

2. An electrochemical sensor for highly sensitive detection of carbendazim according to claim 1, characterized in that: In the LDMS@CCN@GCT nanocomposite material, the content range of each component is as follows: the mass proportion of LDMS is 30-50%, the mass proportion of CCN is 25-35%, and the mass proportion of GCT is 25-35%.

3. An electrochemical sensor for highly sensitive detection of carbendazim according to claim 1, characterized in that: The thickness of LDMS@CCN@GCT nanocomposites on the GCE surface is 80-200 μm.

4. A method for preparing an electrochemical sensor for highly sensitive detection of carbendazim according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Preparation of uniform CCN@GCT@LDMS suspension: First, equal masses of CCN and GCT were added to N,N-dimethylformamide (DMF) solution, and continuous magnetic stirring was performed under ultrasonic environment to obtain a uniformly dispersed CCN@GCT suspension; then, a certain amount of LDMS was added to the above solution, and the LDMS addition ratio was 50% of the total mass of LDMS, CCN and GCT, and ultrasonic dispersion and mixing were performed again to obtain a uniformly mixed CCN@GCT@LDMS suspension; (2) Preparation of CCN@GCT@LDMS / GCE working electrode: The CCN@GCT@LDMS uniform suspension was droplet-coated onto the pre-polished GCE surface and dried under an infrared lamp to obtain a CCN@GCT@LDMS / GCE working electrode. (3) Preparation of an electrochemical sensor for highly sensitive detection of carbendazim: Using a platinum wire electrode as an auxiliary electrode and a saturated calomel electrode as a reference electrode, the CCN@GCT@LDMS / GCE working electrode, auxiliary electrode, and reference electrode were placed in a three-electrode glass electrolytic cell to form an electrochemical sensor for highly sensitive detection of carbendazim.

5. The method for preparing an electrochemical sensor for highly sensitive detection of carbendazim according to claim 4, characterized in that: In the step (1), the ultrasonic dispersion time is 90 to 180 minutes, and the ultrasonic power is 180W.

6. The method for preparing an electrochemical sensor for highly sensitive detection of carbendazim according to claim 4, characterized in that: In the step (2), the infrared lamp drying time is 5 to 15 minutes.

7. The method for preparing an electrochemical sensor for highly sensitive detection of carbendazim according to claim 4, characterized in that: In the step (2), in order to construct the target working electrode, the surface of the glassy carbon electrode is pretreated by wet sand grinding, and the surface of the glassy carbon electrode is polished by ultrasonic cleaning to obtain a glassy carbon electrode with a clean surface and free of impurities.

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