CN114235918B - Method for detecting carbendazim by adopting intrinsic defect porous carbon material - Google Patents

Abstract

The invention discloses a method for detecting carbendazim using intrinsically defective porous carbon materials: (1) preparation of intrinsically defective porous carbon materials; (2) preparation of modified electrodes; (3) preparation of standard solutions; (4) ) Standard curve drawing; in the process of actually detecting the content of carbendazim, replace the standard solution of carbendazim with the sample to be tested, measure the oxidation peak current value at the peak position of the oxidation peak, and bring the oxidation peak current value into From the obtained linear equation, the content of carbendazim in the sample to be tested can be calculated. The porous carbon material prepared in the present invention is rich in defect structures and can form more active sites; it can increase the active area of the electrode and speed up the transfer rate of electrons on the electrode surface. The detection method of the present invention is simple to operate, low in cost, and can detect High accuracy.

Description

A method for detecting carbendazim using intrinsically defective porous carbon materials

Technical field

The present invention relates to the technical field of detecting carbendazim, and in particular to a method for detecting carbendazim using intrinsically defective porous carbon materials.

Background technique

Carbendazim is a systemic broad-spectrum fungicide of the benzimidazole family. Its structure contains a stable benzimidazole ring, which can exist in the soil for a long time, thereby promoting the accumulation of carbendazim in plants and in turn aggravating food Enrichment of carbendazim in . Carbendazim is potentially toxic to humans and can cause endocrine system disorders and cancer. Many countries have established maximum residue limits on crops.

Electrochemical sensing technology has received more and more attention in carbendazim detection due to its advantages such as high sensitivity, low cost, short analysis time, and easy operation. Therefore, it is of great practical significance to establish an accurate, simple, and highly sensitive electrochemical determination method for carbendazim.

Contents of the invention

The object of the present invention is to provide a method for detecting carbendazim using intrinsically defective porous carbon materials, which includes the following steps:

(1) Preparation of intrinsically defective porous carbon materials: Mix 1,10-phenanthroline and Na ₂ CO ₃ evenly, raise the temperature to 880-920°C under the protection of inert gas and maintain it for 0.5-1.5 hours. After cooling, black color is obtained The solid material is washed and dried to obtain nitrogen-doped porous carbon. Under the protection of inert gas, the nitrogen-doped porous carbon is heated to 1100-1200°C and held for 2.5-3.5 hours to remove nitrogen. After cooling, intrinsic defects are obtained. porous carbon materials;

(2) Preparation of modified electrode: Disperse the intrinsically defective porous carbon material prepared in step (1) into N,N-dimethylformamide to make a suspension of 0.8 to 1.2 mg/mL. Drop it onto the surface of a clean glassy carbon electrode, and after drying, you can obtain the modified electrode;

(3) Preparation of standard solution: Weigh the carbendazim solid fraction and dissolve it in ethanol to make a mother solution, then take a certain amount of the mother solution and add it to the phosphate buffer solution, and adjust the volume to obtain a series of carbendazim standard solutions to be tested with different concentrations;

(4) Drawing of the standard curve: The three-electrode system, that is, the modified electrode prepared in step (2) is used as the working electrode, the saturated calomel electrode is used as the reference electrode, and the platinum wire electrode is used as the counter electrode. Insert the system containing multiple In the electrolytic cell of the bacterium standard solution, after enrichment for 200 to 220 seconds under the condition of 0.2V, perform a square wave voltammetric scan in the range of 0.4 to 1.2V, and record the oxidation peak current value of 0.8±0.05V; this oxidation peak There is a good linear relationship between the current value and the carbendazim concentration in the range of 0.01 to 1.00 μmol/L, and a linear equation is obtained; in the process of actually detecting the carbendazim content, the above-mentioned carbendazim standard solution is replaced with the sample to be tested, Substituting the oxidation peak current value measured at 0.8±0.05V into the resulting linear equation, the content of carbendazim in the sample to be tested can be calculated.

Further, in step (1), the mass ratio of 1,10-phenanthroline and Na ₂ CO ₃ is 1:1.

Further, in step (1), grind 1,10-phenanthroline and Na ₂ CO ₃ in a mortar to mix them evenly; the inert gas is nitrogen; the temperature is raised at 3°C/min under the protection of inert gas. The rate is increased to 900°C and maintained for 1 hour. After natural cooling, a black solid material is obtained. After washing and drying, the nitrogen-doped porous carbon is obtained. Under the protection of inert gas, the nitrogen-doped porous carbon is heated at a heating rate of 5°C/min. The temperature is maintained at 1150°C for 2 hours to remove nitrogen. After cooling, the intrinsically defective porous carbon material is obtained.

Further, the washing described in step (1) is to wash the black solid material with hot water at 80°C for 2 to 3 times, and the drying is to dry at 100°C for 12 hours.

Further, in step (2), the intrinsically defective porous carbon material prepared in step (1) is dispersed into N,N-dimethylformamide, and a suspension of 2 mg/mL is first prepared, and then dispersed by ultrasonic. Take the upper suspension and dilute it to a suspension of 1.0 mg/mL.

Further, in step (2), 4 μL of suspension with a concentration of 1.0 mg/mL is dropped onto the surface of a clean glassy carbon electrode, and after drying, a modified electrode can be obtained.

Further, in step (3), the solid carbendazim is weighed, dissolved in ethanol, diluted, and fixed to volume to prepare a mother solution of 10 mmol/L; the concentration of the phosphate buffer is 0.1 mol/L, and the pH value is 6.0.

Further, the enrichment time of step (4) is 210s.

Further, the linear equation described in step (4) is:

I _p (CBZ) = 46.9286C _CBZ +0.1705 (R ² = 0.999)

Among them, I _p is the oxidation peak current (μA), C is the concentration of carbendazim (μmol/L), and the detection limit is 0.0061 μmol/L.

Compared with the prior art, the present invention has the following beneficial effects:

(1) Intrinsic carbon defects formed by changes such as atom deletion and lattice distortion in carbon materials themselves are widely present in carbon-based materials; research shows that intrinsic defect-rich carbon materials have strong polarity and are better than doped ones. Similar materials of heteroatoms. The formation of defects affects the electronic symmetry in the aromatic ring, thereby creating a heterogeneous composition and catalytically active centers by adjusting the spin density and charge density of carbon atoms. Rational design of intrinsic defects within the carbon skeleton can affect the overall charge state of undoped carbon nanomaterials, increase active site density, and thereby enhance electrocatalytic performance. The present invention uses a porous carbon material rich in defect structures to prepare a modified electrode for electrochemical detection of carbendazim. The porous carbon material can increase the active area of the electrode, significantly accelerate the transfer rate of electrons on the electrode surface, and at the same time, More active sites are formed on the surface, and a larger amount of carbendazim is concentrated on the electrode surface, thereby achieving rapid and sensitive determination of carbendazim;

(2) The detection method of the present invention is simple to operate, low in cost, has high detection accuracy, can quickly and effectively detect carbendazim, and can be used for grassroots supervision and detection with simple conditions.

Description of the drawings

Figure 1 shows the CV curves of GCE, N-PC/GCE and D-PC/GCE in 0.1mol/L phosphate buffer;

Figure 2 shows the CV curves of GCE, N-PC/GCE and D-PC/GCE in 1mol/LKCl containing 5mmol/LK ₃ Fe(CN) ₆ ;

Figure 3 shows the impedance diagram of GCE, N-PC/GCE and D-PC/GCE in 1mol/LKCl containing 5mmol/LK ₃ Fe(CN) ₆ /K ₄ Fe(CN) ₆ ;

Figure 4 shows the SWV diagram of D-PC/GCE in solutions with different carbendazim concentrations, and the relationship between oxidation peak current and carbendazim concentration.

Detailed ways

The following examples facilitate a better understanding of the present invention, but do not limit the present invention. The experimental methods in the following examples are all conventional methods unless otherwise specified. The test materials used in the following examples were all purchased from conventional biochemical reagent stores unless otherwise specified. The quantitative tests in the following examples were repeated three times, and the results were averaged.

The electrochemical workstation used in the experiment is PalmSens4C type. The square wave voltammetry parameters are set as follows: potential step: 0.004V; potential increase: 0.025V; frequency: 25Hz.

Example 1

A method for detecting carbendazim includes the following steps:

(1) Preparation of intrinsically defective porous carbon materials: Grind 1,10-phenanthroline and Na ₂ CO ₃ in a mortar at a mass ratio of 1:1 to mix them evenly, then place them in a corundum ark and place Enter the tube furnace, pass nitrogen at a certain flow rate for 1 hour to exhaust the air, then raise it to 900°C at a heating rate of 3°C/min and keep it for 1 hour. After cooling, a black solid material is obtained. The obtained black solid is stirred under magnetic stirring. Immerse in hot water at 80°C and wash to dissolve the inorganic impurities. Wash 3 times. Then collect the black solid and dry it at 100°C for 12 hours to obtain nitrogen-doped porous carbon (N-PC). Under nitrogen protection, N-PC is dried at 5 The heating rate is increased to 1150°C for 3 hours to remove nitrogen. After cooling, the intrinsically defective porous carbon material (D-PC) is obtained;

(2) Preparation of modified electrode: Disperse the intrinsically defective porous carbon material prepared in step (1) into N,N-dimethylformamide. First prepare a 2 mg/mL suspension, disperse it with ultrasound and then let it stand. 0.5h, dilute the upper suspension to a suspension of 1.0 mg/mL, drop 4 μL of the suspension with a concentration of 1.0 mg/mL onto the surface of a clean glassy carbon electrode, and dry it to obtain a modified electrode (D-PC/ GCE);

(3) Preparation of standard solution: Weigh the carbendazim solid, dissolve it with ethanol, dilute it, and adjust it to a constant volume to prepare a mother solution of 10 mmol/L. Then take a certain amount of the mother solution and add phosphoric acid with a concentration of 0.1 mol/L and a pH value of 6.0. In the buffer solution, dilute the volume to obtain a series of concentrations: 0.01μmol/L, 0.025μmol/L, 0.050μmol/L, 0.10μmol/L, 0.25μmol/L, 0.50μmol/L, 0.75μmol/L and 1.0μmol/ L of carbendazim standard solution to be tested;

(4) Drawing of the standard curve: The three-electrode system, that is, the modified electrode prepared in step (2) is used as the working electrode, the saturated calomel electrode is used as the reference electrode, and the platinum wire electrode is used as the counter electrode. Insert the system containing multiple In the electrolytic cell of the bacterium standard solution, after enrichment for 210 seconds under the condition of 0.2V, perform a square wave voltammetric scan in the range of 0.4 to 1.2V, and record the oxidation peak current value of 0.8±0.05V; the oxidation peak current value There is a good linear relationship with the concentration of carbendazim in the range of 0.01 to 1.00 μmol/L, and a linear equation is obtained:

I _p (CBZ) = 46.9286C _CBZ +0.1705 (R ² = 0.999)

Where I _p is the oxidation peak current (μA), C is the concentration of carbendazim (μmol/L);

In the actual process of detecting the content of carbendazim, replace the above-mentioned carbendazim standard solution with the sample to be tested, and substitute the oxidation peak current value measured at 0.8±0.05V into the resulting linear equation to calculate the sample to be tested The content of carbendazim in .

Example 2

A method for detecting carbendazim includes the following steps:

(1) Preparation of intrinsically defective porous carbon materials: Grind 1,10-phenanthroline and Na ₂ CO ₃ in a mortar at a mass ratio of 1:1 to mix them evenly, then place them in a corundum ark and place Enter the tube furnace, introduce nitrogen at a certain flow rate for 1 hour, exhaust the air, and then raise it to 880°C at a heating rate of 3°C/min and maintain it for 0.5h. After cooling, a black solid material is obtained. The obtained black material is stirred under magnetic stirring. Immerse the solid in hot water at 80°C and wash to dissolve the inorganic impurities. Wash twice, then collect the black solid and dry it at 100°C for 12 hours to obtain nitrogen-doped porous carbon (N-PC). Under nitrogen protection, the N-PC is Raise the temperature to 1100°C for 2.5 hours at a heating rate of 5°C/min to remove nitrogen. After cooling, the intrinsically defective porous carbon material (D-PC) is obtained;

(4) Preparation of modified electrode: Disperse the intrinsically defective porous carbon material prepared in step (1) into N,N-dimethylformamide. First prepare a 2 mg/mL suspension, disperse it with ultrasonic and then let it stand. 0.5h, dilute the upper suspension to a suspension of 1.0 mg/mL, drop 4 μL of the suspension with a concentration of 1.0 mg/mL onto the surface of a clean glassy carbon electrode, and dry it to obtain a modified electrode (D-PC/ GCE);

(5) Preparation of standard solution: Weigh the carbendazim solid, dissolve it with ethanol, dilute it, and adjust it to a constant volume to prepare a mother solution of 10 mmol/L. Then take a certain amount of the mother solution and add phosphoric acid with a concentration of 0.1 mol/L and a pH value of 6.0. In the buffer solution, dilute the volume to obtain a series of concentrations: 0.01μmol/L, 0.025μmol/L, 0.050μmol/L, 0.10μmol/L, 0.25μmol/L, 0.50μmol/L, 0.75μmol/L and 1.0μmol/ L of carbendazim standard solution to be tested;

(4) Drawing of the standard curve: The three-electrode system, that is, the modified electrode prepared in step (2) is used as the working electrode, the saturated calomel electrode is used as the reference electrode, and the platinum wire electrode is used as the counter electrode. Insert the system containing multiple In the electrolytic cell of the bacterium standard solution, after enrichment for 200 seconds under the condition of 0.2V, perform a square wave voltammetry scan in the range of 0.4 to 1.2V, and record the oxidation peak current value of 0.8±0.05V; the oxidation peak current value There is a good linear relationship with the concentration of carbendazim in the range of 0.01 to 1.00 μmol/L, and a linear equation is obtained:

I _p (CBZ) = 46.9286C _CBZ +0.1705 (R ² = 0.999)

Where I _p is the oxidation peak current (μA), C is the concentration of carbendazim (μmol/L);

In the actual process of detecting the content of carbendazim, replace the above-mentioned carbendazim standard solution with the sample to be tested, and substitute the oxidation peak current value measured at 0.8±0.05V into the resulting linear equation to calculate the sample to be tested The content of carbendazim in .

Example 3

A method for detecting carbendazim includes the following steps:

(1) Preparation of intrinsically defective porous carbon materials: Grind 1,10-phenanthroline and Na ₂ CO ₃ in a mortar at a mass ratio of 1:1 to mix them evenly, then place them in a corundum ark and place Enter the tube furnace, introduce nitrogen at a certain flow rate for 1 hour and exhaust the air, then raise it to 920°C at a heating rate of 3°C/min and keep it for 1.5h. After cooling, a black solid material is obtained. The obtained black material is stirred under magnetic stirring. Immerse the solid in hot water at 80°C and wash to dissolve inorganic impurities. Wash three times. Then collect the black solid and dry it at 100°C for 12 hours to obtain nitrogen-doped porous carbon (N-PC). Under nitrogen protection, N-PC is Raise the temperature to 1200°C for 3.5 hours at a heating rate of 5°C/min to remove nitrogen. After cooling, the intrinsically defective porous carbon material (D-PC) is obtained;

(6) Preparation of modified electrode: Disperse the intrinsically defective porous carbon material prepared in step (1) into N,N-dimethylformamide. First prepare a 2 mg/mL suspension, disperse it with ultrasound and then let it stand. 0.5h, dilute the upper suspension to a suspension of 1.0 mg/mL, drop 4 μL of the suspension with a concentration of 1.0 mg/mL onto the surface of a clean glassy carbon electrode, and dry it to obtain a modified electrode (D-PC/ GCE);

(7) Preparation of standard solution: Weigh the carbendazim solid, dissolve it with ethanol, dilute it, and adjust it to a constant volume to prepare a mother solution of 10 mmol/L. Then take a certain amount of the mother solution and add phosphoric acid with a concentration of 0.1 mol/L and a pH value of 6.0. In the buffer solution, dilute the volume to obtain a series of concentrations: 0.01μmol/L, 0.025μmol/L, 0.050μmol/L, 0.10μmol/L, 0.25μmol/L, 0.50μmol/L, 0.75μmol/L and 1.0μmol/ L of carbendazim standard solution to be tested;

(4) Drawing of the standard curve: The three-electrode system, that is, the modified electrode prepared in step (2) is used as the working electrode, the saturated calomel electrode is used as the reference electrode, and the platinum wire electrode is used as the counter electrode. Insert the system containing multiple In the electrolytic cell of the bacterium standard solution, after enrichment for 200 seconds under the condition of 0.2V, perform a square wave voltammetry scan in the range of 0.4 to 1.2V, and record the oxidation peak current value of 0.8±0.05V; the oxidation peak current value There is a good linear relationship with the concentration of carbendazim in the range of 0.01 to 1.00 μmol/L, and a linear equation is obtained:

I _p (CBZ) = 46.9286C _CBZ +0.1705 (R ² = 0.999)

Where I _p is the oxidation peak current (μA), C is the concentration of carbendazim (μmol/L);

In the actual process of detecting the content of carbendazim, replace the above-mentioned carbendazim standard solution with the sample to be tested, and substitute the oxidation peak current value measured at 0.8±0.05V into the resulting linear equation to calculate the sample to be tested The content of carbendazim in .

Embodiment 4 Determination of spike recovery rate of the method of the present invention

Sample measurement method: Take about 5.0g of sample, use 30mL of ethanol solution to extract ultrasonically for 10 minutes, centrifuge, filter, collect the extract, evaporate in a 60°C water bath until 3 to 5mL of solution remains, add ethanol to adjust the volume to 10mL of solution. . During measurement, 100 μL of the solution was added to 10 mL of 0.1 mol/L phosphate buffer (pH 6.0), and the carbendazim content was measured according to the method of Example 1.

In order to study the effectiveness of the D-PC/GCE modified electrode of Example 1 in actual detection, river water, lettuce and soil were selected as actual samples for simultaneous detection. Carbendazim was artificially added to the sample, and three concentrations were set: 0.05 μmol/L, 0.15 μmol/L, and 0.25 μmol/L. Under the same test conditions as in Example 1, the spike recovery rate was calculated. The results are shown in Table 1. As shown, the recovery rates of river water, lettuce and soil samples are 99.3% ~ 102.0%, 94.8% ~ 98.0% and 96.0% ~ 103.6% respectively, which shows that D-PC/GCE has good applicability in actual sample detection .

Table 1 Recovery rate of carbendazim detected by D-PC/GCE

Example 5

The glassy carbon electrode (GCE), the nitrogen-doped porous carbon modified glassy carbon electrode (N-PC/GCE) of Example 1 and the intrinsically defective porous carbon modified glassy carbon electrode (D-PC/GCE) were studied at 0.1 mol/L. The CV curve in phosphate buffer, as shown in Figure 1, the CV of D-PC/GCE in 0.1 mol/L phosphate buffer does not show any redox peak (curve a), which shows that D-PC itself does not Has redox properties. Then 10 μmol/L carbendazim was added to 0.1mol/L phosphate buffer. At this time, a pair of redox peaks appeared on different electrodes. Carbendazim showed a weak electrochemical signal on GCE, while the modified N -PC, the electrochemical signal is significantly enhanced, which indicates that N-PC has good electrocatalytic performance for carbendazim. However, compared with N-PC/GCE, carbendazim exhibited stronger electrochemical signals on D-PC/GCE, which may be due to the intrinsic defects in D-PC serving as catalytically active sites that enhance the response to polypeptides. Electrocatalytic effect of bacterium.

Example 6

In order to calculate the electroactive area of glassy carbon electrode (GCE), nitrogen-doped porous carbon modified glassy carbon electrode (N-PC/GCE) and intrinsically defective porous carbon modified glassy carbon electrode (D-PC/GCE), at 1 mol/ Add 5mmol/LK ₃ Fe(CN) ₆ to L of KCl solution, use K ₃ [Fe(CN) ₆ ] as the probe, and use cyclic voltammetry (CV) for testing (scan rate: 0.025, 0.050, 0.075, 0.100 , 0.125, 0.150, 0.175 and 0.200V·s ^-1 ), the results are shown in Figure 2. It can be seen from Figure 2 that when the CV scan rate increases from 0.025V·s ^-1 to 0.200V·s ^-1 , the reduction peak current (I _p ) of K ₃ [Fe(CN) ₆ ] gradually increases and (I _p ) of different electrodes has a good linear relationship with ν ^1/2 . There is no conclusion. If there is no linear relationship, the active area cannot be calculated through the following equations.

d in Figure 2 is the relationship between the reduction peak current and the square root of the scan rate. It can be seen from Figure 2-d that according to Equation: I _p =-2.69×10 ⁵ AD ^1/2 n ^3/2 v ^1/2 C ₀ , GCE, N-PC/GCE and D can be calculated from the slope values of I _p and ν ^1/2 in the figure -The electroactive areas of PC/GCE are 0.0607cm ² , 0.0644cm ² and 0.0656cm ² respectively. It can be seen that the modification of D-PC/GCE can increase the electroactive area of the electrode.

Example 7

Study the glassy carbon electrode (GCE), the nitrogen-doped porous carbon modified glassy carbon electrode (N-PC/GCE) of Example 1 and the intrinsically defective porous carbon modified glassy carbon electrode (D-PC/GCE) in the presence of 1 mmol/LK ₃ Fe(CN) ₆ /K ₄ Fe(CN) ₆ impedance diagram in 1mol/LKCl solution to understand the electron transfer rate of different electrodes. The results are shown in Figure 3. In Figure 3, GCE has a larger semicircle diameter, while the diameters of N-PC/GCE and D-PC/GCE are relatively small, indicating that modification of GCE by N-PC and D-PC can significantly reduce its electrochemical sensing. The resistance value of the interface. At the same time, it can be seen from the illustration that the semicircle diameter of D-PC/GCE is slightly smaller than that of N-PC/GCE. This shows that D-PC/GCE has a more excellent electron transfer rate and can accelerate the electrochemical reaction of CBZ on the electrode.

Example 8

Study the square wave voltammetry spectra of the intrinsically defective porous carbon modified glassy carbon electrode (D-PC/GCE) of Example 1 in carbendazim solutions of different concentrations (panel a in Figure 4), as well as the oxidation peak The relationship between current and concentration (b in Figure 4). As shown in Figure 4, the oxidation peak current of carbendazim increases as the concentration increases, showing a good linear relationship in the range of 0.01 to 1.00 μM. The linear equation is: I _p (CBZ) = 46.9286C _CBZ +0.1705 (R ² =0.999); the calculated detection limit of carbendazim is 0.0061 μM.

Comparing the intrinsically defective porous carbon modified glassy carbon electrode (D-PC/GCE) of Example 1 with other electrodes in the prior art, the results are shown in Table 2. From Table 2, it can be seen that the porous carbon prepared by the present invention Modified glassy carbon electrode (D-PC/GCE) has better electrochemical sensing performance and has obvious advantages.

Table 2 Comparison of sensing performance between D-PC/GCE and other electrodes for detecting carbendazim

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Claims (9)

1. A method for detecting carbendazim using intrinsically defective porous carbon materials, which is characterized by including the following steps: (1) Preparation of intrinsically defective porous carbon materials: Mix 1,10-phenanthroline and Na ₂ CO ₃ evenly, raise the temperature to 880-920°C under the protection of inert gas and maintain it for 0.5-1.5 hours. After cooling, black color is obtained The solid material is washed and dried to obtain nitrogen-doped porous carbon. Under the protection of inert gas, the nitrogen-doped porous carbon is heated to 1100-1200°C and held for 2.5-3.5 hours to remove nitrogen. After cooling, intrinsic defects are obtained. porous carbon materials; (2) Preparation of modified electrode: Disperse the intrinsically defective porous carbon material prepared in step (1) into N,N-dimethylformamide to make a suspension of 0.8 to 1.2 mg/mL. Drop it onto the surface of a clean glassy carbon electrode, and after drying, you can obtain the modified electrode; (3) Preparation of standard solution: Weigh the carbendazim solid fraction and dissolve it in ethanol to make a mother solution, then take a certain amount of the mother solution and add it to the phosphate buffer solution, and adjust the volume to obtain a series of carbendazim standard solutions to be tested with different concentrations; (4) Drawing of the standard curve: The three-electrode system, that is, the modified electrode prepared in step (2) is used as the working electrode, the saturated calomel electrode is used as the reference electrode, and the platinum wire electrode is used as the counter electrode. Insert the system containing multiple In the electrolytic cell of the bacterium standard solution, after enrichment for 200 to 220 seconds under the condition of 0.2V, perform a square wave voltammetric scan in the range of 0.4 to 1.2V, and record the oxidation peak current value of 0.8±0.05V; this oxidation peak There is a good linear relationship between the current value and the carbendazim concentration in the range of 0.01 to 1.00 μmol/L, and a linear equation is obtained; in the process of actually detecting the carbendazim content, the above-mentioned carbendazim standard solution is replaced with the sample to be tested, Substituting the oxidation peak current value measured at 0.8±0.05V into the resulting linear equation, the content of carbendazim in the sample to be tested can be calculated. 2. The method according to claim 1, characterized in that: in step (1), the mass ratio of 1,10-phenanthroline and Na ₂ CO ₃ is 1:1. 3. The method according to claim 1, characterized in that: in step (1), 1,10-phenanthroline and Na ₂ CO ₃ are ground in a mortar to mix them evenly; the inert gas is nitrogen; Raise the temperature to 900°C at a heating rate of 3°C/min under the protection of an inert gas and maintain it for 1 hour. After natural cooling, a black solid material is obtained. After washing and drying, the nitrogen-doped porous carbon is obtained. Under the protection of an inert gas, the nitrogen-doped porous carbon is obtained. The heteroporous carbon was heated to 1150°C at a heating rate of 5°C/min and held for 2 hours to remove nitrogen. After cooling, the intrinsically defective porous carbon material was obtained. 4. The method according to claim 1, characterized in that: the washing in step (1) is to wash the black solid material with hot water at 80°C for 2 to 3 times, and the drying is to dry at 100°C for 12 hours. 5. The method according to claim 1, characterized in that: in step (2), the intrinsically defective porous carbon material prepared in step (1) is dispersed into N,N-dimethylformamide, first prepared A suspension of 2 mg/mL is then dispersed by ultrasonic, and the upper suspension is diluted to a suspension of 1.0 mg/mL. 6. The method according to claim 1, characterized in that: in step (2), 4 μL of suspension with a concentration of 1.0 mg/mL is dropped onto the surface of a clean glassy carbon electrode, and the modified electrode can be obtained after drying. 7. The method according to claim 1, characterized in that: in step (3), weigh the carbendazim solid, dissolve it with ethanol, dilute it, and adjust the volume to prepare a mother liquor of 10 mmol/L; the concentration of the phosphate buffer solution It is 0.1mol/L and the pH value is 6.0. 8. The method according to claim 1, characterized in that: the enrichment time of step (4) is 210s. 9. The method according to claim 1, characterized in that: the linear equation described in step (4) is: I _p (CBZ) = 46.9286C _CBZ +0.1705 (R ² = 0.999) Among them, I _p is the oxidation peak current (μA), C is the concentration of carbendazim (μmol/L), and the detection limit is 0.0061 μmol/L.