Carbon black nanogold composite material-based electrochemical sensor, and preparation method and application thereof

Abstract

The application relates to the technical field of electrochemical detection, and discloses a carbon black and nano-gold composite material-based electrochemical sensor and a preparation method and application thereof. The sensor preparation steps are as follows: 1, carbon black dispersion liquid preparation; 2, nano-gold particle material (AuNPs) preparation by using a sodium citrate reduction method; and 3, nano-gold / carbon black modified composite electrode preparation. When used, the carbon black and gold nano-composite electrode sensor is used as a working electrode, an Ag / AgCl electrode is used as a reference electrode, a platinum electrode is used as an auxiliary electrode, and LSV detection is adopted. The sensor has the advantages of high detection sensitivity, fast detection speed, convenient use and the like. The sensor prepared by the application can measure the content of the phenolic compound cannabidiol in cannabinoids, and the sensor has the advantages of no need for complex sample pretreatment, simple operation, short detection time and low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical analysis, and particularly relates to a carbon black nanogold composite material electrochemical sensor and a preparation method and application thereof. BACKGROUND

[0002] The most valuable component in medicine is cannabidiol (CBD), which is one of the main components of industrial hemp, extracted from female hemp plants, and has the second highest content among 85 special compounds contained in industrial hemp, with an average content of about 40%. Cannabidiol has the physiological activity functions of blocking the adverse effects of some polyphenols on the human nervous system, blocking breast cancer metastasis, treating epilepsy, resisting rheumatoid arthritis, resisting insomnia, etc. It is necessary to detect cannabidiol, a cannabinoid compound.

[0003] However, the current detection of cannabidiol is basically carried out in professional laboratories, and such a detection method has high cost and long detection process time, and it is difficult to meet the timeliness requirement of phenolphthalein detection in actual application

[0004] Carbon black (CB) is also called carbon black, which is an amorphous carbon with loose structure and light texture, and is black and powdery. Carbon black has excellent electrical properties and large specific surface area, and as a modification material, it can help the working electrode to determine the sample to be measured, reduce the response overpotential, increase the peak current, reduce the detection limit, improve the selectivity and sensitivity. It can effectively reduce the overpotential of the oxidation-reduction reaction of chemical substances, improve the oxidation-reduction reversibility of molecules, and has good application prospect in the field of electrochemistry.

[0005] Metal nanomaterials refer to metal materials with at least one spatial dimension meeting the nanometer level or composed of nanomaterials as constituent units. Metal nanoparticles are superior to ordinary nanoparticles and have the advantages of large specific surface area, many active sites, good oxidation-reduction activity, high conductivity, etc. In the field of electroanalytical chemistry, metal nanoparticles are widely used as functional nanomaterials. Especially, noble metal nanomaterials have characteristics superior to general nanoparticles, can provide a large number of active sites, have excellent catalytic activity, and have good biocompatibility, so they have good application prospect in the field of electrochemical sensors. SUMMARY

[0006] The primary object of the present application is to provide a carbon black nanogold composite material electrochemical sensor, which is an electrochemical sensor of a three-electrode system with carbon black material loaded with nanogold particles polymerized on the surface of an electrode as a working electrode (i.e. CB / AuNPs / GCE). The sensor can further improve the detection sensitivity of substances and can be specifically used for the detection of cannabidiol, a cannabinoid compound.

[0007] The second object of the present application is to provide a preparation method of the carbon black nanogold composite material-based electrochemical sensor. The mixed suspension of nanogold and carbon black is drop-coated on the surface of an electrode, and a working electrode is obtained after drying; or the dried electrode is placed in a buffer solution of BRB-acetonitrile, PBS or HAc-NaAc, and a working electrode in a three-electrode system is prepared by further polymerizing the carbon black nanogold to the surface of the electrode under cyclic voltammetry in a three-electrode system.

[0008] In the preparation method, the ratio of nanogold and carbon black material in the mixed suspension is 1:1-5; and the solvent of the mixed suspension of nanogold and carbon black includes dimethylformamide, water, methanol, ethanol, water or N,N-dimethylacetamide.

[0009] In the preparation method, the carbon black dispersion liquid is prepared by weighing carbon black into a solvent to prepare a carbon black dispersion, and ultrasonic treatment to obtain a carbon black dispersion liquid of 1.0-5.0 mg / mL.

[0010] Further, the carbon black dispersion liquid is obtained by the following method: 1 mg of carbon black is added into a solvent of dimethylformamide (DMF): water = 1:1 to prepare a carbon black dispersion, and ultrasonic treatment is performed at 59 Hz for 15 min; and a carbon black dispersion liquid of 1.0 mg / mL is obtained.

[0011] In the preparation method, the particle size of nanogold is 1-100 nm; and the sodium citrate reduction method is preferably used for preparation.

[0012] Further, the preparation method of nanogold particles is as follows: 1.03 mL of HAuCL4 and 98.97 mL of deionized water are mixed, and then the mixture is heated to 110°C. When the temperature reaches 110°C, 10 mL of 1.45X10 -2 M tri-sodium citrate is rapidly injected into the boiling solution. The mixture is stirred vigorously under reflux for 30 minutes, and the color of the reaction solution gradually changes from colorless to light red, light purple, and finally to wine red. After the color remains unchanged, the colloidal solution is continuously stirred at room temperature until the solution is cooled. After the reaction is completed, the solution is stored at 4°C for standby use before use. The ultraviolet-visible absorption peak of the AuNPS is about 522 nm (UV-2450 spectrophotometer, Shimadzu, Japan).

[0013] Further, the preparation method of the carbon black nanogold suspension is preferably as follows: 2.0 mg of carbon black is weighed into a solvent of dimethylformamide: water = 1:1 to prepare a carbon black dispersion, and 1 mL of nanogold is removed and added into the carbon black dispersion liquid for ultrasonic stirring until a uniform suspension is formed, to obtain a carbon black nanogold suspension; the mass ratio of carbon black and nanogold is 1:1, and the content of carbon black nanogold in the suspension is 1 mg / mL.

[0014] Further, the drop coating amount of the carbon black nanometer gold suspension on the electrode is 8.0 μL; the carbon black nanometer gold suspension is drop coated on the surface of the glassy carbon electrode, and dried under an infrared lamp; or the dried electrode is placed in a buffer solution of Breytan-Robinson (phosphoric acid, boric acid and acetic acid) : acetonitrile = 5:2, and the carbon black nanometer gold is further polymerized to the electrode surface through cyclic voltammetry in a three-electrode system.

[0015] The preparation method further preferably comprises the following steps: first, the carbon black dispersion liquid is drop coated on the electrode surface, and a layer of carbon black film is left on the electrode surface after drying; then, the mixed suspension of nanometer gold and carbon black is drop coated on the surface of the carbon black film and dried.

[0016] The preparation method further comprises the following step: the carbon black nanometer gold is further polymerized to the electrode surface through cyclic voltammetry in a three-electrode system. The working electrode in the three-electrode system is prepared under the following conditions: potential range: 0-0.8 V; scanning number: 20; electrolyte: BRB-acetonitrile buffer solution, pH = 3-9; preferably, pH = 5.0.

[0017] Further, the bare glassy carbon electrode is polished with 0.3 μm and 0.05 μm Al2O3 powder suspensions on the suede for 3-5 min, and then the polished bare electrode is sequentially cleaned in anhydrous ethanol and ultrapure water for 3 min, and then rinsed with double-distilled water and dried with nitrogen. 8.0 uL of CB / AuNPs dispersion liquid is accurately taken by a pipette and drop coated on the polished glassy carbon electrode surface, and then dried under an infrared lamp to obtain a CB / AuNPs electrode.

[0018] A third object of the present application is to provide an application method of the carbon black nanometer gold composite material-based electrochemical sensor, wherein, in the application, the carbon black material loaded with nanometer gold particles is polymerized to the electrode surface as a working electrode, an Ag / AgCl electrode is used as a reference electrode, a platinum electrode is used as an auxiliary electrode, and LSV is used for detection.

[0019] Further, the sensor is placed in an electrolyte buffer solution for detection, and the oxidation peak current value is recorded, and the concentration of the sample cannabidiol is measured according to a working curve.

[0020] Further, the voltage range of LSV is 0.2 V to 0.8 V, the potential width is 4 mV, the amplitude is 50 mV, the pulse width is 0.06 s, and the pulse period is 0.5 s; and the electro-polymerization conditions are as follows: potential range: 0-0.8 V; scanning number: 20; electrolyte: a buffer solution of BRB-acetonitrile, PBS or HAc-NaAc containing cannabidiol, pH = 3-9, preferably, pH = 5.0.

[0021] The present application studies the electrochemical properties of the CB / AuNPs electrode in 5.0 mmol / L [Fe(CN)6]3- / 4- The electrochemical performance of different modified electrodes in the probe solution was shown. The electron transfer was good. The reduced oxygen carbon blackene had a good electron transmission rate, and its peak current would be higher than that of the bare electrode. At the same time, the redox peak current of CB / GCE was lower than that of AuNPs / GCE (AuNPs is nano gold, and GCE is glassy carbon electrode), because CB (carbon black) is distributed on the surface of graphite due to π-π conjugation, and has the ability to absorb or lose electrons due to the surface rich in oxygen-containing functional groups, which will hinder the transfer of electrons. Only the simultaneous addition of CB and AuNPs can synergistically improve the electron transmission rate of the electrode. Due to the synergistic effect between CB and AuNPs, CB / AuNPs / GCE showed excellent electrochemical performance, with the highest peak redox current.

[0022] The present application optimizes the experimental conditions, and the influence of the pH value of the buffer solution. pH is an important parameter that directly affects electrochemical reactions. The electrochemical response of cannabidiol in CB / AuNPs / GCE in different pH environments was studied. Figure 7 The CV of 20 μmol / L cannabidiol at different pH values was shown. With the increase of pH value, the anodic peak moved in the negative direction. The influence of pH on the response peak current of cannabidiol was shown in Figure 7 . In the pH range of 3.0 to 5.0, the anodic peak current always increased with the increase of pH value. When the pH changed from 5.0 to 9.0, the anodic peak current gradually decreased. Cannabidiol had the highest response anodic peak at pH = 5.0. In addition, the anodic peak potential linearly decreased with the increase of pH value.

[0023] In order to further understand the electrochemical oxidation mechanism, the CV of 20 μmol / L cannabidiol at various scan rates (v, mV / s) was recorded using CB / AuNPs / GCE, as shown in Figure 8 . The CV at different scan rates was plotted in the figure. It can be seen from the figure that the redox peaks of cannabidiol increased with the increase of scan rate, but at the same time the background current also increased, which may be because high scan rate will increase the charging current of double layer. In addition, with the increase of scan rate, the anodic peak of cannabidiol moves positively, while the cathodic peak moves negatively. As Figure 8 , the peak current of the anode and cathode of cannabidiol is highly related to v 1 / 2 , indicating that the electrochemical oxidation of cannabidiol is a diffusion-controlled process.

[0024] Further study the influence of cannabidiol on different modified electrodes (see Figure 4), the electrochemical response of 20 μmol / L cannabidiol on different electrodes was recorded in BRB buffer (pH = 5.0) by CV. The CB / AuNPs / GCE nanocomposite material showed significant electrocatalytic ability for the electrochemical oxidation of cannabidiol. The addition of electrocatalytic metal particles further improved the conductivity of the composite material, and also increased the surface area of carbon black and improved the electron transfer rate.

[0025] Further research detects the enrichment potential and enrichment time: the enrichment potential is 0.1v, and the enrichment time is 120s.

[0026] Further explore CB / AuNPs / GCE for the determination of cannabidiol, under the optimal experimental conditions, a series of different concentrations of CBD standard solution are determined by LSV method, because it has higher current sensitivity and better resolution than CV. Under the above selected optimal experimental conditions (in pH 5.0 BRB acetonitrile buffer, the sweep speed is 50mV / s), LSV method is used to determine in the potential range of 0.2-0.8V. The concentration range is 0.25 μmol / L-50 μmol / L.

[0027] Preparation of standard curve:

[0028] CB / AuNPs / GCE is used as the working electrode, platinum electrode is used as the auxiliary electrode, and Ag / AgCl is used as the reference electrode, the peak current of cannabidiol is detected in BRB-acetonitrile buffer containing different concentrations of cannabidiol compounds by LSV in a three-electrode system, a linear relationship between the peak current of cannabidiol and the concentration is established, and the corresponding linear regression equation is obtained.

[0029] Based on the carbon black nanogold composite material electrochemical sensor of the application, the detection range of cannabidiol is 0.25 μmol / L-50 μmol / L, and the minimum detection limit is 0.09 μM.

[0030] In summary, the application has the following beneficial effects:

[0031] The application uses carbon black and gold nanoparticles as a composite material (CB / AuNPs), carbon black has excellent electrical properties and a large specific surface area, which helps the working electrode to determine the sample to be measured, can reduce the response potential, increase the peak current, reduce the detection limit, improve the selectivity and sensitivity. Gold nanoparticles can effectively activate the electrocatalytic process, have good electrocatalytic activity, and the combination of carbon black and gold nanoparticles is effective.

[0032] Specifically provided is a high-sensitivity electrochemical sensor, which adopts a traditional three-electrode system and is based on LSV to test the electrochemical performance of the electrochemical sensor. When in use, the CB / AuNPs / GCE is used as a working electrode, the Ag / AgCl electrode is used as a reference electrode, and the platinum electrode is used as an auxiliary electrode to form a traditional three-electrode system. Based on the irreversible oxidation of the phenol group of cannabidiol, the peak current of the cannabidiol to be measured is determined by LSV with the cannabidiol to be measured as a sample, so that the quantitative detection of the cannabidiol is realized. The sensor has the characteristics of high detection sensitivity, strong specificity, wide linear range, and convenient use. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application, and are used to explain the application together with the examples of the application, and do not constitute a limitation to the application, and in the drawings:

[0034] Figure 1 :CB / AuNPs transmission electron microscopy diagram.

[0035] Figure 2 : X-ray diffraction spectrum diagram of carbon black nanogold material.

[0036] Figure 3 : Ultraviolet-visible absorption spectrum diagram of nanogold particles.

[0037] Figure 4 : CV current response of different modified electrodes in BRB-acetonitrile buffer solution (pH = 5.0) containing 20 μmol / L CBD at a scanning rate of 50 mV / s.

[0038] Figure 5 : Optimization of enrichment potential (A) and enrichment time (B) of the modified electrode to 20 μmol / L CBD.

[0039] Figure 6 : (A) CV current response of different modified electrodes in 5 mmol / L [Fe(CN)6] (1:1) in 0.1 mol / L KCl; (B) Nyquist plot of different electrodes for EIS measurement in the presence of 5 mmol / L [Fe(CN)6] (1:1) in 0.1 mol / L KCl. 3- / 4- 3- / 4-

[0040] Figure 7 : CV recorded in 20 μmol / L CBD solution at different pH values of 3-9;

[0041] (A) CV of different p H base solutions for detecting cannabidiol (from right to left, p H is 3, 4, 5, 6, 7, 8, and 9, respectively); ​​

[0042] (B) and (C) are the current value and oxidation peak potential relationship curve of the buffer solution of different pH of cannabidiol, respectively.

[0043] Figure 8 (A) The effect of CV scan rate on the redox peak current of 20 μmol / L cannabidiol in CB / AuNPs / GCE in BRB-acetonitrile buffer (pH 5.0); (B) The linear relationship between the numerical value of the reduction peak current and the square root of the scan rate; (C) The linear relationship between the size of the reduction peak potential and the logarithm of the scan rate.

[0044] Figure 9 The LSV current response of CB / AuNPs / GCE in BRB-acetonitrile buffer (pH 5.0) with (A) the increase of cannabidiol concentration, and the calibration curve of LSV current and (B) cannabidiol concentration.

[0045] Figure 10 The inhibition degree of various interfering substances on CB / AuNPs / GCE when detecting CBD. DETAILED DESCRIPTION

[0046] The following examples are intended to further illustrate the present application, but not to limit the present application.

[0047] Example 1

[0048] The preparation method of the electrochemical sensor for analyzing cannabidiol and its components is characterized by the following specific steps:

[0049] S1, Preparation of carbon black dispersion liquid: 1.0 mg of carbon black is weighed and added into dimethylformamide (DMF): water = 1:1 to prepare a carbon black dispersion, which is ultrasonically treated at 59 Hz for 15 min. A 1.0 mg / mL carbon black dispersion liquid is prepared. A small amount (8 mL) of the dispersion liquid is moved to the working electrode surface of the glassy carbon electrode in three steps by a pipette, 2 mL each time. Then, the solvent is allowed to evaporate, and a layer of carbon black "film" (CB) is left on the electrode surface.

[0050] S2, Preparation of gold nanoparticles AuNPs: 1.03 mL of 24.28 mmol / L HAuCL4 and 98.97 mL of deionized water are mixed by sodium citrate reduction method, and then the mixture is heated to 110°C. When the temperature reaches 110°C, 10 mL of 1.45X10 -2M trisodium citrate was quickly injected into the boiling solution. The mixture was stirred vigorously under reflux for 30 min (25 °C), and the color of the reaction solution gradually changed from colorless to light red, light purple, and finally to wine red. After the color remained unchanged, the colloid solution was continuously stirred at room temperature until the solution cooled. After the reaction was completed, the solution was stored at 4 °C before use. The UV-visible absorption peak of AuNPs (UV-2450 spectrophotometer, Shimadzu, Japan) was about 522 nm. See Figure 1 Figure 3 .

[0051] S3, Preparation of gold nanoparticle / carbon black modified composite electrode: 2.0 mg of carbon black was accurately weighed and added to (dimethylformamide (DMF): water (1:1)) to prepare a carbon black dispersion. 1 mL of nanogold was removed and added to the carbon black dispersion liquid and stirred under ultrasonic until a uniform suspension was formed to obtain a CB / AuNPs suspension.

[0052] S4: The bare glassy carbon electrode was polished on the suede with 0.3 μm and 0.05 μm A12O3 powder suspensions for 3-5 min, respectively, and then the polished bare electrode was ultrasonically treated. It was sequentially placed in anhydrous ethanol, ultrapure water and ultrasonically cleaned for 3 min each. Then it was washed with double-distilled water and blown dry with nitrogen. 8.0 uL of CB / AuNPs dispersion was accurately removed with a pipette and drop-coated on the polished glassy carbon electrode surface, and then dried under an infrared lamp to obtain a CB / AuNPs electrode.

[0053] Figure 1 The transmission electron microscopy (TEM) image of the carbon black nanogold composite material shows that the gold nanoparticles were successfully prepared and uniformly modified on the electrode surface, and the carbon black nanogold composite electrode was successfully modified. Through XRD data analysis, a strong diffraction peak of amorphous carbon at 38° can be seen, which is consistent with the transmission electron microscopy result (Figure 3), proving that the introduction of gold nanoparticles is successfully combined with carbon black, which is more conducive to improving the conductivity in the process of electron transfer. Figure 2

[0054] The UV-visible absorption spectrum of the prepared gold nanoparticles is shown in Figure 2, and the absorption spectrum of AuNPs has a clear absorption peak at 522 nm. Figure 3

[0055] The prepared carbon black / nanogold electrochemical sensor was placed in a buffer solution containing the sample to be measured BRB-acetonitrile, and cyclic voltammetry (CV) detection was performed. The current response of the composite material was the largest when detected by GCE, CB / GCE, AuNPs / GCE and CB / AuNPs / GCE, respectively. See Figure 4 Figure 4 .

[0056] Further research was conducted on the enrichment potential and enrichment time during detection. The enrichment potential was 0.1 V, and the enrichment time was 120 s. See Figure 5​​Figure 5 .

[0057] The electrochemical properties of different modified electrodes in 5.0 mmol / L [Fe(CN)6] 3- / 4- probe solution were studied by CV. Figure 6 The corresponding CV curves are shown. It can be seen that the peak current response of the bare electrode, carbon black, gold nanoparticles, carbon black gold nanoparticles composite electrode, and composite material is the highest. The corresponding interface resistance was characterized by EIS, which proved the accuracy of the results.

[0058] The pH was adjusted to 3.0-9.0 in BRB-acetonitrile buffer solution before use.

[0059] The electrochemical response of CBD in different pH environments was studied. Figure 7 The CV of 20 μmol / L CBD at different pH values is shown. As shown in Figure 7 A, with the increase of pH value, the anodic peak of CBD moves in the negative direction. In the pH range of 3.0 to 5.0, the anodic peak current always increases with the increase of pH value. When the pH changes from 5.0 to 9.0, the anodic peak current gradually decreases. CBD has the highest response anodic peak at pH=5.0. The optimal pH is 5.0.

[0060] In order to further understand the electrochemical oxidation mechanism, as Figure 8 shown, the CV of 20 μmol / L CBD at various scan rates (v, mV / s) was recorded using CB / AuNPs / GCE. The CV at different scan rates is plotted in the figure. Figure 8 As can be seen from Figure 8 A, the redox peaks of CBD increase with the increase of scan rate, and the background current also increases, which may be because high scan rate will increase the charging current of double layer. In addition, with the increase of scan rate, the anodic peak of CBD moves positively, while the cathodic peak moves negatively. As shown in Figure 8 B, the anodic peak current of CBD is highly correlated with v 1 / 2 , indicating that the electrochemical oxidation of CBD is a diffusion-controlled process. The linear regression equation is as follows: Ipa(μA)=1.7963v 1 / 2 (mv / s)-7.5497 (R 2 =0.9919).

[0061] Further explore CB / AuNPs / GCE for the determination of cannabidiol, under the optimal experimental conditions, using LSV method to determine a series of different concentrations of cannabidiol (CBD) standard solution, because it has higher current sensitivity and better resolution than CV. Under the above selected optimal experimental conditions (in BRB acetonitrile buffer solution with pH 5.0, the sweep speed is 50mV / s), in the potential range of 0.2-0.8V, the potential width is 4mV, the amplitude is 50mV, the pulse width is 0.06s, and the pulse period is 0.5s; the electro-polymerization condition is: potential range: 0-0.8V; scan number: 20 circles; the concentration range is 0.25μmol / L-50μmol / L. Figure 9 .

[0062] According to the relationship between peak current and concentration, a standard curve is drawn. The linear equation is: Ipa(μA) = 0.4164c CBD (μmol / L) + 0.8267, R 2 = 0.99.

[0063] Repeatability test: In order to study the stability and reproducibility of CB / AuNPs / GCE, five independently manufactured electrodes were determined in BRB-acetonitrile buffer solution (pH 5.0) with a fixed concentration of 20μmol / L CBD, and the corresponding current was recorded. The results show that the modified electrode has good stability and reproducibility, and the relative standard deviation is 1.73%. In addition, the application also studies the preparation of different batches of composite materials to modify the electrode, and the obtained data has good reproducibility.

[0064] Anti-interference test: The anti-interference of the electrode is studied by adding organic compounds (0.1mmol / L phenol, 0.1mmol / L m-dihydroxybenzene, 0.1mmol / L o-dihydroxybenzene, 0.1mmol / L p-dihydroxybenzene or 0.1mmol / L p-acetamidophenol) or inorganic ions (1mmol / L CuCl2, 0.1mmol / L MnSO4, 0.1mmol / L FeCl3 or 0.1mmol / L HClO). As Figure 10 shown, compared with the current response of 20μmol / L CBD, none of them shows obvious interference signal, and the above research results prove that the developed electrode has excellent selectivity for CBD molecules.

Claims

1. An application of an electrochemical sensor based on carbon black nano-gold composite material in detecting the content of cannabidiol, characterized in that: The electrochemical sensor is a three-electrode system electrochemical sensor in which a carbon black material loaded with gold nanoparticles is polymerized onto the electrode surface as the working electrode; A mixed suspension of gold nanoparticles and carbon black is dropped onto the electrode surface and dried to obtain a working electrode; alternatively, the dried electrode is placed in a BRB-acetonitrile buffer solution and carbon black and gold nanoparticles are further polymerized onto the electrode surface by cyclic voltammetry in a three-electrode system to prepare a working electrode in the three-electrode system; Preparation of carbon black dispersion: Weigh carbon black and add it to solvent to prepare carbon black dispersion, and ultrasonicate it to obtain a 1 mg / mL carbon black dispersion. First, a carbon black dispersion droplet is applied to the electrode surface, leaving a carbon black film on the electrode surface after drying. Then, a mixed suspension of gold nanoparticles and carbon black is applied to the carbon black film surface and dried. The ratio of the nano-gold and carbon black materials in the mixed suspension is 1:1; the solvent of the mixed suspension of nano-gold and carbon black includes: a solvent with a ratio of dimethylformamide to water = 1:1, dimethylformamide, methanol, ethanol, water or N,N-dimethylacetamide; The working electrode of the three-electrode system was prepared by further polymerizing carbon black nano-gold onto the electrode surface by cyclic voltammetry. The conditions were as follows: potential range: 0-0.8 V; electrolyte: BRB-acetonitrile buffer solution, pH = 5; In application, a carbon black material loaded with gold nanoparticles is polymerized onto the electrode surface as the working electrode, an Ag / AgCl electrode is used as the reference electrode, and a platinum electrode is used as the auxiliary electrode, and LSV detection is adopted; The sensor is placed in an electrolyte buffer for detection; the oxidation peak current value is recorded, and the concentration of cannabidiol in the sample is measured according to the working curve; The measurement conditions are as follows: in BRB-acetonitrile buffer at pH 5.0, a scan rate of 50 mV / s, a potential width of 4 mV in the potential range of 0.2-0.8 V, an amplitude of 50 mV, a pulse width of 0.06 s, and a pulse period of 0.5 s.

2. The use according to claim 1, characterized in that Gold nanoparticles were prepared by sodium citrate reduction method.

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