CN114235918A

CN114235918A - A method for detecting carbendazim using intrinsically defective porous carbon materials

Info

Publication number: CN114235918A
Application number: CN202111498388.9A
Authority: CN
Inventors: 牙禹; 韦良; 杨晶; 黄信龙; 闫飞燕; 谢丽萍; 王彦力; 梁静; 蒋翠文; 李焘; 罗丽红; 宁德娇; 唐莉; 王静; 郑鹭飞
Original assignee: Guangxi Zhuang Nationality Autonomous Region Academy of Agricultural Sciences; Nanning Normal University
Current assignee: Guangxi Zhuang Nationality Autonomous Region Academy of Agricultural Sciences; Nanning Normal University
Priority date: 2021-12-09
Filing date: 2021-12-09
Publication date: 2022-03-25
Anticipated expiration: 2041-12-09
Also published as: CN114235918B

Abstract

The invention discloses a method for detecting carbendazim by adopting intrinsic defect porous carbon material: (1) preparation of intrinsic defect porous carbon material; (2) preparation of modified electrode; (3) preparation of standard solution; (4) preparation of standard solution; ) the drawing of the standard curve; in the process of actually detecting the content of carbendazim, the standard solution of carbendazim is replaced with the sample to be tested, and the peak oxidation current value is measured at the peak position of the oxidation peak, and the peak oxidation current value is brought into In 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; the active area of the electrode can be increased, and the transfer rate of electrons on the electrode surface can be accelerated. High accuracy.

Description

Method for detecting carbendazim by adopting intrinsic defect porous carbon material

Technical Field

The invention relates to the technical field of carbendazim detection, in particular to a method for detecting carbendazim by adopting an intrinsic defect porous carbon material.

Background

Carbendazim is a systematic broad-spectrum bactericide of benzimidazole family, contains stable benzimidazole ring in the structure, and can exist in soil for a long time, thereby promoting the accumulation of carbendazim in plants and further intensifying the enrichment of carbendazim in food. Carbendazim has potential toxicity to human body, and can cause endocrine system disorder and cancer. The maximum residual limits on crops have been established in many countries.

Electrochemical sensing technology is receiving more and more attention in carbendazim detection due to its advantages of high sensitivity, low cost, short analysis time, simple operation, etc. Therefore, the establishment of an accurate, simple and high-sensitivity carbendazim electrochemical determination method has important practical significance.

Disclosure of Invention

The invention aims to provide a method for detecting carbendazim by adopting an intrinsic defect porous carbon material, which comprises the following steps of:

(1) preparation of intrinsic defect porous carbon material: mixing 1, 10-phenanthroline and Na₂CO₃Uniformly mixing, heating to 880-920 ℃ under the protection of inert gas, keeping for 0.5-1.5 h, cooling to obtain a black solid substance, washing and drying to obtain nitrogen-doped porous carbon, heating the nitrogen-doped porous carbon to 1100-1200 ℃ under the protection of inert gas, keeping for 2.5-3.5 h to remove nitrogen elements, and cooling to obtain an intrinsic defect porous carbon material;

(2) preparing a modified electrode: dispersing the intrinsic defect porous carbon material prepared in the step (1) into N, N-dimethylformamide to prepare 0.8-1.2 mg/mL suspension, dripping the suspension onto the surface of a clean glassy carbon electrode, and drying to obtain a modified electrode;

(3) preparation of a standard solution: weighing carbendazim solid, dissolving in ethanol to prepare a mother solution, adding a certain amount of the mother solution into a phosphoric acid buffer solution, and performing constant volume to obtain a series of carbendazim standard solutions to be measured with different concentrations;

(4) drawing a standard curve: inserting a three-electrode system, namely the three-electrode system with the modified electrode prepared in the step (2) as a working electrode, the saturated calomel electrode as a reference electrode and the platinum wire electrode as a counter electrode into an electrolytic cell containing a carbendazim standard solution, carrying out square wave volt-ampere scanning within the range of 0.4-1.2V after enriching for 200-220 s under the condition of 0.2V, and recording the oxidation peak current value of 0.8 +/-0.05V; the oxidation peak current value and the carbendazim concentration are in a good linear relation within the range of 0.01-1.00 mu mol/L to obtain a linear equation; in the process of actually detecting the carbendazim content, the carbendazim standard solution is replaced by a sample to be detected, and the oxidation peak current value measured at 0.8 +/-0.05V is substituted into the linear equation, so that the content of the carbendazim in the sample to be detected can be calculated.

Further, in the step (1), 1, 10-phenanthroline and Na₂CO₃The mass ratio of (A) to (B) is 1: 1.

Further, in the step (1), 1, 10-phenanthroline and Na are added₂CO₃Grinding in a mortar to mix them uniformly; the inert gas is nitrogen; raising the temperature to 900 ℃ at the heating rate of 3 ℃/min under the protection of inert gas and keeping the temperature for 1h, naturally cooling to obtain a black solid substance, washing and drying to obtain nitrogen-doped porous carbon, raising the temperature of the nitrogen-doped porous carbon to 1150 ℃ at the heating rate of 5 ℃/min under the protection of inert gas and keeping the temperature for 2h to remove nitrogen elements, and cooling to obtain the intrinsic defect porous carbon material.

Further, the washing in the step (1) is washing the black solid matter with hot water at 80 ℃ for 2-3 times, and the drying is drying at 100 ℃ for 12 hours.

Further, in the step (2), the intrinsic defect porous carbon material prepared in the step (1) is dispersed in N, N-dimethylformamide to prepare a suspension of 2mg/mL, and then the suspension is subjected to ultrasonic dispersion, and the suspension at the upper layer is diluted into a suspension of 1.0 mg/mL.

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

Further, in the step (3), weighing carbendazim solid, dissolving the carbendazim solid with ethanol, diluting the carbendazim solid, and preparing the carbendazim solid into mother liquor with the concentration of 10 mmol/L; the concentration of the phosphate buffer solution is 0.1mol/L, and the pH value is 6.0.

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

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

I_p(CBZ)＝46.9286C_CBZ+0.1705(R²＝0.999)

wherein I_pThe oxidation peak current (. mu.A) and C were the concentration of carbendazim (. mu. mol/L) with a detection limit of 0.0061. mu. mol/L.

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

(1) intrinsic carbon defects formed by the changes of atom deletion, lattice distortion and the like of the carbon material are widely existed in the carbon-based material; research shows that the intrinsic defect-rich carbon material has stronger polarity and is superior to similar materials doped with heteroatoms. The formation of defects affects the electron symmetry in the aromatic ring, thereby forming non-uniform components and catalytically active centers by adjusting the spin density and charge density of the carbon atoms. The intrinsic defects are reasonably designed in the carbon skeleton, so that the overall charge state of the undoped carbon nano material can be influenced, the density of active sites is increased, and the electrocatalytic performance is enhanced. According to the invention, a porous carbon material rich in defect structures is adopted to prepare the modified electrode for electrochemical detection of carbendazim, the porous carbon material can increase the active area of the electrode, remarkably accelerate the transfer rate of electrons on the surface of the electrode, and simultaneously form more active sites on the surface of the electrode to enrich a larger amount of carbendazim on the surface of the electrode, thereby realizing rapid and sensitive determination of the carbendazim;

(2) the detection method provided by the invention is simple and convenient to operate, low in cost and high in detection accuracy, can be used for quickly and effectively detecting carbendazim, and can be used for basic supervision and detection with crude conditions.

Drawings

FIG. 1 is a CV curve of GCE, N-PC/GCE and D-PC/GCE in 0.1mol/L phosphate buffer;

FIG. 2 shows the results of the analysis of GCE, N-PC/GCE and D-PC/GCE in a medium containing 5mmol/LK₃Fe(CN)₆CV profile in 1 mol/LKCl;

FIG. 3 shows the ratio of GCE, N-PC/GCE and D-PC/GCE at 5mmol/L K₃Fe(CN)₆/K₄Fe(CN)₆1 mol/LKCl;

FIG. 4 is a SWV graph and oxidation peak current versus carbendazim concentration graph of D-PC/GCE in different carbendazim concentration solutions.

Detailed Description

The following examples are given to facilitate a better understanding of the invention, but do not limit the invention. The experimental procedures in the following examples are conventional unless otherwise specified. The test materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified. In the quantitative tests in the following examples, three replicates were set up and the results averaged.

The electrochemical workstation used for the experiment is of PalmSens4C type, and the parameters of the square wave voltammetry are set as follows: potential step change: 0.004V; potential amplification: 0.025V; frequency: 25 Hz.

Example 1

A method of detecting carbendazim, comprising the steps of:

(1) preparation of intrinsic defect porous carbon material: 1, 10-phenanthroline and Na are mixed according to the mass ratio of 1:1₂CO₃Grinding in a mortar to uniformly mix the materials, placing the mixture in a corundum ark, placing the corundum ark in a tubular furnace, introducing nitrogen at a certain flow rate for 1h to exhaust air, raising the temperature to 900 ℃ at the heating rate of 3 ℃/min and keeping the temperature for 1h, cooling to obtain a black solid matter, soaking the obtained black solid matter in hot water at the temperature of 80 ℃ under magnetic stirring to wash and dissolve inorganic impurities for 3 times, collecting the black solid matter, drying at the temperature of 100 ℃ for 12h to obtain nitrogen-doped porous carbon (N-PC), raising the temperature of the N-PC to 1150 ℃ at the heating rate of 5 ℃/min under the protection of nitrogen, keeping the temperature for 3h to remove nitrogen elements, and cooling to obtain an intrinsic defect porous carbon material (D-PC);

(2) preparing a modified electrode: dispersing the intrinsic defect porous carbon material prepared in the step (1) into N, N-dimethylformamide to prepare 2mg/mL suspension, standing for 0.5h after ultrasonic dispersion, taking the upper suspension to dilute into 1.0mg/mL suspension, taking 4 mu L of suspension with the concentration of 1.0mg/mL to drop on the surface of a clean glassy carbon electrode, and drying to obtain a modified electrode (D-PC/GCE);

(3) preparation of a standard solution: weighing carbendazim solid, dissolving with ethanol, diluting, and fixing volume to prepare 10mmol/L mother liquor, adding a certain amount of mother liquor into phosphoric acid buffer solution with concentration of 0.1mol/L, pH value of 6.0, and fixing volume to obtain a series of carbendazim standard solutions to be tested with concentrations of 0.01 μmol/L, 0.025 μmol/L, 0.050 μmol/L, 0.10 μmol/L, 0.25 μmol/L, 0.50 μmol/L, 0.75 μmol/L and 1.0 μmol/L respectively;

(4) drawing a standard curve: inserting a three-electrode system, namely the three-electrode system with the modified electrode prepared in the step (2) as a working electrode, the saturated calomel electrode as a reference electrode and the platinum wire electrode as a counter electrode into an electrolytic cell containing a carbendazim standard solution, carrying out square wave voltammetric scanning within the range of 0.4-1.2V after enriching for 210s under the condition of 0.2V, and recording the oxidation peak current value of 0.8 +/-0.05V; the oxidation peak current value and the carbendazim concentration are in a good linear relation within the range of 0.01-1.00 mu mol/L, and a linear equation is obtained:

I_p(CBZ)＝46.9286C_CBZ+0.1705(R²＝0.999)

wherein I_pIs oxidation peak current (μ A), C is concentration of carbendazim (μmol/L);

in the process of actually detecting the carbendazim content, the carbendazim standard solution is replaced by a sample to be detected, and the oxidation peak current value measured at 0.8 +/-0.05V is substituted into the linear equation, so that the content of the carbendazim in the sample to be detected can be calculated.

Example 2

A method of detecting carbendazim, comprising the steps of:

(1) preparation of intrinsic defect porous carbon material: 1, 10-phenanthroline and Na are mixed according to the mass ratio of 1:1₂CO₃Grinding in a mortar to uniformly mix the materials, placing the mixture in a corundum ark, placing the corundum ark in a tubular furnace, introducing nitrogen at a certain flow rate for 1h to exhaust air, raising the temperature to 880 ℃ at the heating rate of 3 ℃/min and keeping the temperature for 0.5h, cooling to obtain a black solid matter, soaking the obtained black solid in hot water at the temperature of 80 ℃ under magnetic stirring to wash and dissolve inorganic impurities, washing for 2 times, collecting the black solid, drying at the temperature of 100 ℃ for 12h to obtain nitrogen-doped porous carbon (N-PC), raising the temperature of the N-PC to 1100 ℃ at the heating rate of 5 ℃/min under the protection of nitrogen and keeping the temperature for 2.5h to remove nitrogen elements, and cooling to obtain an intrinsic defect porous carbon material (D-PC);

(4) preparing a modified electrode: dispersing the intrinsic defect porous carbon material prepared in the step (1) into N, N-dimethylformamide to prepare 2mg/mL suspension, standing for 0.5h after ultrasonic dispersion, taking the upper suspension to dilute into 1.0mg/mL suspension, taking 4 mu L of suspension with the concentration of 1.0mg/mL to drop on the surface of a clean glassy carbon electrode, and drying to obtain a modified electrode (D-PC/GCE);

(5) preparation of a standard solution: weighing carbendazim solid, dissolving with ethanol, diluting, and fixing volume to prepare 10mmol/L mother liquor, adding a certain amount of mother liquor into phosphoric acid buffer solution with concentration of 0.1mol/L, pH value of 6.0, and fixing volume to obtain a series of carbendazim standard solutions to be tested with concentrations of 0.01 μmol/L, 0.025 μmol/L, 0.050 μmol/L, 0.10 μmol/L, 0.25 μmol/L, 0.50 μmol/L, 0.75 μmol/L and 1.0 μmol/L respectively;

(4) drawing a standard curve: inserting a three-electrode system, namely the three-electrode system with the modified electrode prepared in the step (2) as a working electrode, the saturated calomel electrode as a reference electrode and the platinum wire electrode as a counter electrode into an electrolytic cell containing a carbendazim standard solution, enriching for 200s under the condition of 0.2V, performing square wave voltammetric scanning within the range of 0.4-1.2V, and recording the oxidation peak current value of 0.8 +/-0.05V; the oxidation peak current value and the carbendazim concentration are in a good linear relation within the range of 0.01-1.00 mu mol/L, and a linear equation is obtained:

I_p(CBZ)＝46.9286C_CBZ+0.1705(R²＝0.999)

Example 3

A method of detecting carbendazim, comprising the steps of:

(1) preparation of intrinsic defect porous carbon material: 1, 10-phenanthroline and Na are mixed according to the mass ratio of 1:1₂CO₃Grinding in mortar to mix them uniformly, placing in corundum ark, placing in tube furnace, introducing nitrogen gas with certain flow rate for 1 hr to exhaust air, heating to 920 deg.C at a heating rate of 3 deg.C/min and maintaining for 1.5 hr, coolingThen obtaining a black solid substance, immersing the obtained black solid substance into hot water at 80 ℃ under magnetic stirring to wash and dissolve inorganic impurities, washing for 3 times, collecting the black solid substance, drying for 12 hours at 100 ℃ to obtain nitrogen-doped porous carbon (N-PC), raising the temperature of the N-PC to 1200 ℃ at a heating rate of 5 ℃/min under the protection of nitrogen, keeping for 3.5 hours to remove nitrogen elements, and cooling to obtain an intrinsic defect porous carbon material (D-PC);

(6) preparing a modified electrode: dispersing the intrinsic defect porous carbon material prepared in the step (1) into N, N-dimethylformamide to prepare 2mg/mL suspension, standing for 0.5h after ultrasonic dispersion, taking the upper suspension to dilute into 1.0mg/mL suspension, taking 4 mu L of suspension with the concentration of 1.0mg/mL to drop on the surface of a clean glassy carbon electrode, and drying to obtain a modified electrode (D-PC/GCE);

(7) preparation of a standard solution: weighing carbendazim solid, dissolving with ethanol, diluting, and fixing volume to prepare 10mmol/L mother liquor, adding a certain amount of mother liquor into phosphoric acid buffer solution with concentration of 0.1mol/L, pH value of 6.0, and fixing volume to obtain a series of carbendazim standard solutions to be tested with concentrations of 0.01 μmol/L, 0.025 μmol/L, 0.050 μmol/L, 0.10 μmol/L, 0.25 μmol/L, 0.50 μmol/L, 0.75 μmol/L and 1.0 μmol/L respectively;

I_p(CBZ)＝46.9286C_CBZ+0.1705(R²＝0.999)

Example 4 measurement of recovery of spiked samples according to the method of the invention

The sample determination method comprises the following steps: taking about 5.0g of sample, carrying out ultrasonic extraction for 10min by using 30mL of ethanol solution, centrifuging, filtering, collecting an extracting solution, evaporating in a water bath at 60 ℃ until 3-5 mL of solution is remained, and adding ethanol to a constant volume to 10mL of solution. For the measurement, 100. mu.L of the solution was added to 10mL of 0.1mol/L phosphate buffer (pH 6.0) to measure the carbendazim content in the same manner as in example 1.

In order to study the effectiveness of the D-PC/GCE modified electrode in practical detection in example 1, river water, lettuce and soil were selected as practical samples for simultaneous detection. Carbendazim was artificially added to the samples, 3 concentrations were set: 0.05 mu mol/L, 0.15 mu mol/L and 0.25 mu mol/L, and under the same test conditions as the example 1, the standard recovery rates are calculated, and the results are shown in Table 1, wherein the recovery rates of Jiangshui, lettuce and soil samples are respectively 99.3% -102.0%, 94.8% -98.0% and 96.0% -103.6%, which indicates that the D-PC/GCE has good applicability in the actual sample detection.

TABLE 1 recovery of carbendazim by D-PC/GCE assay

Example 5

To investigate CV curves of the Glassy Carbon Electrode (GCE), the nitrogen-doped porous carbon-modified glassy carbon electrode (N-PC/GCE) of example 1 and the intrinsic-defect porous carbon-modified glassy carbon electrode (D-PC/GCE) in 0.1mol/L phosphate buffer, as shown in FIG. 1, CV of D-PC/GCE in 0.1mol/L phosphate buffer did not show any redox peak (curve a), indicating that D-PC itself has redox characteristics. Then 10 mu mol/L carbendazim is added into 0.1mol/L phosphate buffer solution, a pair of redox peaks appear on different electrodes, the carbendazim shows a weak electrochemical signal on GCE, and the electrochemical signal is obviously enhanced after the modification of N-PC, which shows that the N-PC has good electrocatalytic performance on the carbendazim. However, carbendazim exhibits a stronger electrochemical signal on D-PC/GCE than N-PC/GCE, probably due to the fact that intrinsic defects in D-PC act as catalytically active sites enhancing electrocatalytic effects on carbendazim.

Example 6

In order to calculate the electric active areas of a Glassy Carbon Electrode (GCE), a nitrogen-doped porous carbon modified glassy carbon electrode (N-PC/GCE) and an intrinsic defect porous carbon modified glassy carbon electrode (D-PC/GCE), 5mmol/LK is added into a 1mol/L KCl solution₃Fe(CN)₆With K₃[Fe(CN)₆]For the probe, a test was performed using Cyclic Voltammetry (CV) (scan rate: 0.025, 0.050, 0.075, 0.100, 0.125, 0.150, 0.175, and 0.200 V.s)^-1) The results are shown in FIG. 2. from FIG. 2, it can be seen that when the scanning rate of CV is from 0.025 V.s^-1Increased to 0.200 V.s^-1，K₃[Fe(CN)₆]Reduction peak current (I) of_p) Of progressively larger and different electrodes_p) And v^1/2With a good linear relationship. Without any conclusion, if not linear, the active area cannot be calculated by the following equation.

D in FIG. 2 is a plot of the reduction peak current versus the square root of the scan rate, as can be seen from FIG. 2-d, in terms of

The equation: i is_p＝－2.69×10⁵AD^1/2n^3/2v^1/2C₀From I in the figure_pAnd v^1/2The values of the slope (D) were calculated to give an electroactive area of 0.0607cm for GCE, N-PC/GCE and D-PC/GCE, respectively²、0.0644cm²And 0.0656cm². Thus, it was found that the modification of D-PC/GCE can increase the electroactive area of the electrode.

Example 7

Study of the content of 1mmol/LK in the Glassy Carbon Electrode (GCE), the nitrogen-doped porous carbon-modified glassy carbon electrode (N-PC/GCE) of example 1 and the intrinsic defect porous carbon-modified glassy carbon electrode (D-PC/GCE)₃Fe(CN)₆/K₄Fe(CN)₆To understand the electron transfer rates of the different electrodes, the results are shown in fig. 3. In FIG. 3, the GCE has a larger semicircular diameter, and the diameters of N-PC/GCE and D-PC/GCE are relatively smaller, which shows that the GCE modified by N-PC and D-PC can significantly reduce the resistance value of the electrochemical sensing interface. Also, as can be seen from the inset, the semi-circle diameter of D-PC/GCE is slightly smaller than that of N-PC/GCE. This shows that D-PC/GCE has more excellent electron transfer rate and can accelerate the electrochemical reaction of CBZ on the electrode.

Example 8

The spectrum of the square wave voltammetry of the intrinsic defect porous carbon modified glassy carbon electrode (D-PC/GCE) in carbendazim solutions with different concentrations (a diagram in FIG. 4) and the oxidation peak current-concentration relationship diagram (b in FIG. 4) of example 1 were studied. As shown in FIG. 4, the oxidation peak current of carbendazim increases with the increase of concentration, and is in a better linear relation in the range of 0.01-1.00 mu M, and the linear equation is as follows: i is_p(CBZ)＝46.9286C_CBZ+0.1705(R²0.999); the detection limit of carbendazim was calculated to be 0.0061 μ M.

Compared with other electrodes in the prior art, the intrinsic defect porous carbon modified glassy carbon electrode (D-PC/GCE) in example 1 has the results shown in Table 2, and the results show that the porous carbon modified glassy carbon electrode (D-PC/GCE) prepared by the invention has better electrochemical sensing performance and obvious superiority from Table 2.

TABLE 2 comparison of the sensing Performance of D-PC/GCE with that of other electrodes for detecting carbendazim

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Claims

1. a method that adopts intrinsic defect porous carbon material to detect carbendazim, is characterized in that, comprises the following steps:

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

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

(3) Preparation of standard solution: Weigh the solid carbendazim and dissolve it in ethanol to prepare a mother solution, then take a certain amount of the mother solution and add it to the phosphate buffer solution, and set the volume to obtain a series of standard solutions of carbendazim 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. In the electrolytic cell of the standard solution of pendant, after enriching at 0.2V for 200-220s, a square wave voltammetry scan was performed in the range of 0.4-1.2V, and the oxidation peak current value of 0.8±0.05V was recorded; the oxidation peak There is a good linear relationship between the current value and the concentration of carbendazim in the range of 0.01 to 1.00 μmol/L, and a linear equation is obtained; in the process of actually detecting the content of carbendazim, the above-mentioned standard solution of carbendazim is replaced with the sample to be tested. Substitute the oxidation peak current value measured at 0.8±0.05V into the obtained linear equation, and the content of carbendazim in the sample to be tested can be calculated.

2. method according to claim 1 is characterized in that: in step (1), the mass ratio of 1,10-o-phenanthroline and Na ₂ CO ₃ is 1:1.

3. according to the described method of claim 1, it is characterized in that: in step (1), by 1,10-o-phenanthroline and Na ₂ CO ₃ are ground in mortar to make them mix; Inert gas is nitrogen; Under the protection of inert gas, the temperature was raised to 900 °C at a heating rate of 3 °C/min and kept for 1 h. After natural cooling, a black solid material was obtained. After washing and drying, nitrogen-doped porous carbon was obtained. Under the protection of inert gas, nitrogen-doped porous carbon was obtained. Heteroporous carbon was raised to 1150 °C at a heating rate of 5 °C/min for 2 h to remove nitrogen elements, and the intrinsic defect porous carbon material was obtained after cooling.

4 . The method according to claim 1 , wherein the washing in step (1) is to wash the black solid matter with hot water at 80° C. for 2 to 3 times, and the drying is to dry at 100° C. for 12 hours. 5 .

5. The method according to claim 1, wherein in step (2), the intrinsic defect porous carbon material prepared in step (1) is dispersed in N,N-dimethylformamide, and the 2 mg/mL suspension, then dispersed by ultrasonic, and the upper suspension was diluted to 1.0 mg/mL suspension.

6 . The method according to claim 1 , wherein in step (2), 4 μL of suspension with a concentration of 1.0 mg/mL is dropped onto a clean glassy carbon electrode surface, and the modified electrode can be obtained after drying. 7 .

7. according to the method described in claim 1, it is characterized in that: in step (3), take by weighing carbendazim solid and be mixed with the mother liquor of 10mmol/L with ethanol dissolving, dilution, constant volume; Described phosphate buffer concentration It is 0.1mol/L, and the pH value is 6.0.

8. The method according to claim 1, wherein the enrichment time of step (4) is 210s.

9. according to the described method of claim 1, it is 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.