Magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite material as well as preparation method and application thereof in chlorpromazine analysis

Abstract

The invention discloses a magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite material as well as a preparation method and application thereof in chlorpromazine analysis, and belongs to the technical field of detection and analysis. The magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite material comprises reduced graphene oxide, Fe3O4 particles are loaded on nanosheets of the reduced graphene oxide to form magnetic reduced graphene oxide, gold nanoparticles are modified on the nanosheets of the magnetic reduced graphene oxide, and the Fe3O4 particles are loaded on the nanosheets of the magnetic reduced graphene oxide to form the magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite material. The gold nanoparticles are grafted with n-octadecanethiol through gold-sulfur bonds. The composite material disclosed by the invention has excellent magnetism, selective adsorption performance on chlorpromazine, conductivity and catalytic activity, and when the composite material is used as an adsorbent for detecting chlorpromazine in animal-derived food by a magnetic solid-phase extraction-electrochemical detection combined technology, the composite material has good anti-interference performance, accuracy and stability.

Description

Technical Field

[0001] This invention belongs to the field of detection and analysis technology, and more specifically, relates to a magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material, its preparation method, and its application in chlorpromazine analysis. Background Technology

[0002] Chlorpromazine (CPZ) is a phenothiazine antibiotic primarily used to treat psychosis and schizophrenia characterized by symptoms such as agitation, hallucinations, and delusions. Currently, the European Union has explicitly banned the use of CPZ in animal husbandry, while China and Japan stipulate that this drug must not be detected in animal-derived foods. In animal husbandry, the illegal use of CPZ can lead to veterinary drug residues that can damage multiple systems in the human body, including the cardiovascular, endocrine, respiratory, and immune systems, potentially causing drowsiness, hypotension, movement disorders, and blood diseases. Therefore, efficient and accurate methods for determining CPZ residues in animal-derived foods are of significant practical importance.

[0003] Among national standard methods, high-performance liquid chromatography (HPLC) is considered the gold standard for determining veterinary drug residues in animal-derived foods due to its strong stability, excellent repeatability, and high industry acceptance. However, this method relies on expensive and sophisticated instruments and requires standardized operation by professional technicians. Furthermore, the sample pretreatment process is complex, and the analysis cycle is relatively long, which severely limits its application in rapid on-site detection scenarios. Electrochemical detection methods, on the other hand, have been gradually developed and applied to the rapid detection of veterinary drug residues in food due to their advantages of simple and portable equipment, convenient operation, fast response, and high detection sensitivity. However, in food analysis, it has been found that most existing electrochemical detection methods are only suitable for simple liquid sample systems. This is because complex food matrices can easily interfere with the electrochemical detection signal, making it difficult to achieve ideal accuracy and reliability. Therefore, a simple and efficient sample pretreatment procedure is essential before electrochemical detection.

[0004] The prior art disclosed in Chinese Patent Document Publication No. CN118913855A is a technique for the determination of nitrofurantoin using a combination of magnetic solid phase extraction and electrochemical detection. This is a related patent previously applied for by our laboratory. It utilizes magnetic solid phase extraction (MSPE) to separate and enrich the target analyte in the sample during the pretreatment process of complex environments and biological samples. The in-situ electrochemical differential pulse voltammetry (DPV) detection of nitrofurantoin is then performed using a magnetic glassy carbon electrode modified with cobalt / nitrogen-doped carbon material.

[0005] Therefore, this application aims to further develop a method for the efficient and accurate determination of CPZ residues in animal-derived foods, based on the combined use of magnetic solid-phase extraction and electrochemical detection. Summary of the Invention

[0006] 1. The problem to be solved To address the technical problem that existing magnetic solid phase extraction-electrochemical detection combined technology cannot efficiently and accurately determine CPZ residues in animal-derived foods, this invention provides a magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material, which, when used as an adsorbent for the combined magnetic solid phase extraction and electrochemical detection of CPZ residues in animal-derived foods, can efficiently and accurately determine CPZ residues in animal-derived foods.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: [1. Magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material] The first aspect of the present invention provides a magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material, comprising reduced graphene oxide, wherein Fe3O4 particles are loaded on the nanosheets of the reduced graphene oxide to form magnetic reduced graphene oxide, and gold nanoparticles are modified on the nanosheets of the magnetic reduced graphene oxide, wherein the gold nanoparticles are grafted with n-octadecyl mercaptan via gold-sulfur bonds.

[0008] As a preferred embodiment of any of the first aspects of the present invention, the Fe3O4 particles have a particle size of 100 nm to 300 nm, and the gold nanoparticles have a particle size of 10 nm to 100 nm.

[0009] Furthermore, the Fe3O4 particles have a particle size of 150 nm to 250 nm, and the gold nanoparticles have a particle size of 30 nm to 70 nm.

[0010] As a preferred embodiment of any of the first aspects of the present invention, the gold nanoparticles have a spherical morphology and a non-spherical morphology.

[0011] Furthermore, the non-spherical morphology includes triangular prisms and rods.

[0012] As a preferred embodiment of any of the first aspects of the present invention, the XRD pattern of the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material shows characteristic diffraction peaks of 2θ at 38.2±0.2°, 44.6±0.2°, 64.9±0.2° and 77.6±0.2°.

[0013] Furthermore, the XRD pattern of the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material shows characteristic diffraction peaks of 2θ at 24.0±0.2°, 30.1±0.2°, 35.2±0.2°, 43.1±0.2°, 53.6±0.2°, 56.8±0.2° and 62.4±0.2°.

[0014] As a preferred embodiment of any of the first aspects of the present invention, the magnetic reduction graphene oxide / hydrophobic gold nanoparticle composite material has a magnetization greater than 20 emu·g. –1 .

[0015] Furthermore, the magnetic reduction graphene oxide / hydrophobic gold nanoparticle composite material exhibits a magnetization greater than 25 emu·g. –1 More preferably, it is greater than or equal to 30 emu·g –1 The optimal value is 30 emu·g –1 ~64 emu·g –1 .

[0016] As a preferred embodiment of any of the first aspects of the present invention, the difference between the ID / IG value of the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material and the ID / IG value of the magnetically reduced graphene oxide is less than or equal to 20.

[0017] Furthermore, the difference is less than or equal to 10, even more preferably less than or equal to 1, and most preferably 0 to 0.5.

[0018] It should be noted that ID represents the defect peak intensity, and IG represents the graphite peak intensity.

[0019] As a preferred embodiment of any of the first aspects of the present invention, the specific surface area of ​​the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material is greater than or equal to 50 m². 2 g –1 More preferably, it is greater than or equal to 60 m 2 g –1 The optimal value is 65m. 2 g –1 ~150 m 2 g –1 .

[0020] [2. Magnetic Reduced Graphene Oxide / Hydrophobic Gold Nanoparticle Composite Material] The second aspect of this invention provides a method for preparing the magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material provided in the first aspect of this invention, comprising the following steps: S1. Synthesis of magnetically reduced graphene oxide; S2. Modify gold nanoparticles on the surface of the magnetically reduced graphene oxide nanosheets. S3. The gold nanoparticles are grafted with n-octadecyl mercaptan via gold-sulfur bonds.

[0021] As a preferred embodiment of any of the first aspects of the present invention, S1 includes the following steps: S1.1 Weigh out graphene oxide and FeCl3 in a mass ratio of (0.1~0.2):(0.3~0.5):(0.1~0.2):(1.5~2):1. 6H2O, trisodium citrate, sodium acetate and polyethylene glycol were placed in a centrifuge tube containing ethylene glycol and subjected to ultrasonic treatment and magnetic stirring in sequence to obtain a uniformly dispersed suspension, wherein the mass-volume ratio of graphene oxide to ethylene glycol was (2.5~5) mg:1 mL. S1.2 Transfer the suspension obtained in S1.1 to a high-pressure reactor lined with polytetrafluoroethylene and react at 200±50℃ for 10~14 hours; S1.3 After the stainless steel high-pressure reactor has cooled naturally to room temperature, the reaction products are collected, washed with ethanol, and dried in a vacuum oven to obtain magnetically reduced graphene oxide.

[0022] As a preferred embodiment of any of the first aspects of the present invention, step S2 includes the following steps: S2.1 Magnetic reduced graphene oxide is dispersed in ultrapure water, ultrasonically treated, and stirred at 0±5 ℃ for 10~30 min to obtain a magnetic reduced graphene oxide suspension with a concentration of 0.2 mg / mL~0.5 mg / mL. S2.2 Add HAuCl4 solution to the magnetically reduced graphene oxide suspension and stir for 0.5~2 h to obtain a mixed solution of magnetically reduced graphene oxide and HAuCl4, wherein the mass ratio of magnetically reduced graphene oxide to HAuCl4 is (3~5):1; S2.3. Over a period of 1 to 5 minutes, while stirring, add sodium borohydride solution dropwise to the mixed solution in S2.2. After the addition is complete, continue stirring for 10 to 20 minutes. The mass ratio of magnetically reduced graphene oxide to sodium borohydride is (5 to 6.5): 1. S2.4. Collect the solid product, wash it with ultrapure water, and dry it in a vacuum oven to obtain a magnetically reduced graphene oxide / gold nanoparticle composite material.

[0023] As a preferred embodiment of any of the first aspects of the present invention, step S3 includes the following steps: S3.1 Place the magnetically reduced graphene oxide / gold nanoparticle composite material in a centrifuge tube containing ethanol, then add an ethanol solution of n-octadecyl mercaptan, shake and mix for 10~14 h to obtain a suspension of the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material, wherein the mass ratio of the magnetically reduced graphene oxide / gold nanoparticle composite material to n-octadecyl mercaptan is (6~8):1. S3.2. Collect the solid product, wash it with ethanol, and dry it in a vacuum oven to obtain a magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material.

[0024] [3. Application of magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite materials] The third aspect of this invention provides the application of the magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material provided in the first aspect of this invention or the magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material prepared by the preparation method provided in the second aspect of this invention in the analysis of chlorpromazine.

[0025] As a preferred embodiment of any aspect of the present invention, the detection method in the application is a magnetic solid-phase extraction-differential pulse voltammetry combined technique, comprising the following steps: M1. Mix the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material with the sample to be tested and vortex for 20~40 min to obtain a mixture. M2. Immerse the magnetic glassy carbon electrode in the mixture in M1 to adsorb the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material. M3. Remove the magnetic glassy carbon electrode and immerse it in the electrolytic cell. Perform differential pulse voltammetry to obtain the differential pulse voltammetry curve. The peak current intensity at 0.68 V is I. p ; M4, peak current intensity I p Substituting the standard curve of chlorpromazine into the magnetic solid-phase extraction-differential pulse voltammetry (MS / VPE) technique, the concentration of chlorpromazine was obtained and denoted as c. CPZ .

[0026] Furthermore, the pretreatment steps of the sample to be tested before detection are in accordance with the Chinese National Standard Method GB31656.4-2021.

[0027] Furthermore, the detection limit of the magnetic solid-phase extraction-differential pulse voltammetry coupled technique is less than or equal to 100 nmol·L⁻¹. –1 More preferably, it is less than or equal to 50 nmol·L –1 The optimal value is 10 nmol·L. –1 ~30 nmol·L –1 .

[0028] As a preferred embodiment of any of the first aspects of the present invention, the method for establishing the standard curve includes the following steps: N1. The magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material was mixed with CPZ standard solutions of different concentrations and vortexed for 20-40 min to obtain a mixture. N2. Immerse the magnetic glassy carbon electrode in the mixture in N1 to adsorb the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material. N3. Remove the magnetic glassy carbon electrode and immerse it in the electrolytic cell. Perform differential pulse voltammetry to obtain the differential pulse voltammetry curve. The peak current intensity at 0.68 V is I. p ; N4. Plot the peak current intensity as the ordinate and the CPZ concentration c as the ordinate. CPZ As the x-axis, construct I p With c CPZ The standard curve between them was obtained, and their relationship equation was fitted.

[0029] As a preferred embodiment of any of the first aspects of the present invention, the standard curve is a two-segment curve: The concentration c of chlorpromazine CPZ Located in the range of 0.1~8 μmol·L –1 At that time, the peak current intensity I p With respect to the concentration c of the chlorpromazine CPZ The linear equation is: I p (μA)=0.881c CPZ (μmol·L –1 +0.346; The concentration c of chlorpromazine CPZ Greater than 8 μmol·L –1 At that time, the peak current intensity I i With respect to the concentration c of the chlorpromazine CPZ The linear equation is: I p (μA)=0.094c CPZ (μmol·L –1 )+6.78.

[0030] Furthermore, linear equation I p (μA)=0.881c CPZ (μmol·L –1 The goodness of fit R² is +0.346. 2 Greater than or equal to 0.995; Linear equation I p (μA)=0.094c CPZ (μmol·L –1 The goodness-of-fit R-value was +6.78. 2 Greater than or equal to 0.990.

[0031] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention is the first to develop a magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material, which combines excellent magnetism, selective adsorption performance for chlorpromazine (CPZ), conductivity, and catalytic activity, thereby realizing the application of magnetic solid-phase extraction-electrochemical detection technology in the detection of CPZ in animal-derived foods. Specifically, the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material developed in this invention can serve as a selective adsorbent for magnetic solid-phase extraction of CPZ, and can also provide excellent conductivity for the electrode in electrochemical detection and enhance the electrochemical detection signal of CPZ. Among these, Fe3O4 particles endow the material with excellent magnetic response characteristics, enabling rapid separation and enrichment of CPZ under an applied magnetic field, while effectively inhibiting the aggregation and stacking of reduced graphene oxide (RGO) sheets. In addition, gold nanoparticles (AuNPs) possess excellent electrocatalytic activity, which can enhance the electrochemical detection signal of CPZ and improve the accuracy and sensitivity of detection. As a two-dimensional nanocarrier, reduced graphene oxide provides a stable loading platform for Fe3O4 and gold nanoparticles, and can achieve efficient adsorption of CPZ through π-π interactions. More importantly, the introduction of n-octadecyl mercaptan (ODT) constructs hydrophobic interaction sites, further improving the adsorption selectivity and adsorption capacity of the composite material for CPZ.

[0032] (2) The method for preparing magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material provided by the present invention has good batch reproducibility and can be produced, applied and promoted in industry.

[0033] (3) This invention is the first to develop a method for detecting chlorpromazine in animal-derived foods based on magnetic solid phase extraction-electrochemical detection technology. This method is based on a magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material. When applied to the determination of CPZ residues in animal-derived foods such as beef and sea bass without the need for additional electrode modification, it shows specificity for CPZ and high detection sensitivity. It has good anti-interference, accuracy and stability, which fully highlights the application potential and practical value of this composite material in the field of chlorpromazine detection in animal-derived foods.

[0034] (4) The method for detecting chlorpromazine in animal-derived foods based on magnetic solid-phase extraction-electrochemical detection technology provided by the present invention, compared with the high performance liquid chromatography (HPLC) in the prior art, does not require eluting chlorpromazine from the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material of the adsorbent, and can directly use the electrode to detect chlorpromazine on the adsorbent; in addition, the pretreatment process and electrochemical detection process in the detection method of the present invention are simplified and the required time is reduced compared with the high performance liquid chromatography; and the detection method of the present invention has a simple process and reasonable design, which greatly improves the efficiency of chlorpromazine detection in animal-derived foods. Attached Figure Description

[0035] Figure 1 : a is a TEM image (1 μm) of MRGO in Example 1; b is a TEM image (500 nm) of MRGO in Example 1. c is a TEM image (100 nm) of MRGO in Example 1. d is a TEM image (1 μm) of MRGO@AuNPs-ODT in Example 1; e is a TEM image (500 nm) of MRGO@AuNPs-ODT in Example 1. f is a TEM image (100 nm) of MRGO@AuNPs-ODT in Example 1. Figure 2 : a is the infrared spectrum of GO, MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT in Example 1; b is the Raman spectrum of GO, MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT in Example 1; Figure 3 : a is the XRD pattern of GO, MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT in Example 1; b is the hysteresis regression curve of Fe3O4 and MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT in Example 1; Figure 4 Bar chart showing the CPZ adsorption capacity of Fe3O4 and MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT in Example 1; Figure 5 The graphs show the DPV detection without adsorbent and the DPV detection when MRGO, MRGO@AuNPs, and MRGO@AuNPs-ODT are used as adsorbents in Example 1. Where: a represents no adsorbent, b represents MRGO as the adsorbent, c represents MRGO@AuNPs as the adsorbent, and d represents MRGO@AuNPs-ODT as the adsorbent; Figure 6 : a is the DPV curve of different concentrations of CPZ when MRGO@AuNPs-ODT is used as the adsorbent in Example 1; b is the standard curve of the MSPE-DPV co-processing technology when MRGO@AuNPs-ODT is used as the adsorbent in Example 1; Figure 7 The graph shows the anti-interference performance of CPZ detected by MSPE-DPV coupled technology when MRGO@AuNPs-ODT is used as the adsorbent in Example 1. Figure 8 The storage stability performance diagram of MRGO@AuNPs-ODT in Example 1 is shown. Figure 9 The graph shows the performance of CPZ detected by MSPE-DPV coupled technology when different batches of MRGO@AuNPs-ODT were used as adsorbents in Example 1. Detailed Implementation

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0038] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0039] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0040] It should be noted that the magnetic glassy carbon electrode (MGCE) needs to be cleaned before use. The specific steps are as follows: First, polish the electrode surface of the MGCE with alumina slurry, then rinse it three times with ultrapure water and ethanol alternately, 5 mL each time, and finally blow the moisture off the electrode surface with nitrogen to obtain a clean MGCE.

[0041] It should be noted that the preparation method of Fe3O4 used in the test example is basically the same as the synthesis steps of magnetic reduced graphene oxide (MRGO) in Example 1, the only difference being that graphene oxide is not added.

[0042] It should be noted that when using electrochemical differential pulse voltammetry (DPV) to detect chlorpromazine (CPZ) in beef or sea bass, the pretreatment steps for beef or sea bass samples are simplified from the Chinese National Standard Method GB 31656.4-2021, as follows: 1. Sample pretreatment: Crush the beef or sea bass sample; 2. CPZ Extraction: Weigh 0.5 g to 1.5 g of the crushed sample and add it to a centrifuge tube containing 10 mL of acetonitrile. Vortex the tube for 1 minute, sonicate for 10 minutes, and then centrifuge at 10,000 rpm for 5 minutes to collect the supernatant. Then, add another 10 mL of acetonitrile to the centrifuge tube, vortex for 1 minute, sonicate for 10 minutes, and then centrifuge at 10,000 rpm for 5 minutes to collect the supernatant. Combine the two supernatants.

[0043] 3. Degreasing the extract: Transfer the combined 20 mL supernatant to a new centrifuge tube, add 10 mL of n-hexane, vortex for 30 seconds, then transfer to a separatory funnel and let stand for 2 minutes. Collect the lower layer solution in a flask.

[0044] 4. Vacuum evaporation: Evaporate the lower layer solution to dryness under reduced pressure at 40 °C, and use 20 mL of 0.1 mol·L⁻¹ solution. –1 Phosphate-buffered saline (PBS) was used to dissolve the residue on the flask wall for subsequent MSPE-DPV detection.

[0045] In addition, for the detection of CPZ in beef or sea bass by high performance liquid chromatography (HPLC), the pretreatment of beef or sea bass samples, CPZ extraction, and degreasing of the extract are the same as for DPV detection. The only difference between the vacuum evaporation procedure and the above steps is that the residue on the flask wall after evaporation is dissolved in 10 mL of H3PO4 solution (pH 4.0). Then, the sample solution containing CPZ is purified using a mixed strong cation exchange solid-phase extraction column (MCX-SPE), as follows: (1) The MCX-SPE column was activated sequentially with 5 mL of methanol and 5 mL of H3PO4 solution (pH 4.0); (2) Dissolve 10 mL of sample solution at a rate of 1-2 mL / min. –1 Flow rate loading; (3) Use 5 mL of 0.1 mol·L –1 Rinse the MCX-SPE column with hydrochloric acid solution; (4) Elute the CPZ adsorbed on the MCX-SPE column with 5 mL of methanol / ammonia solution (95 / 5, V / V).

[0046] (5) The eluent was dried by nitrogen and then reconstituted in 0.8~1.2 mL of 0.055wt% H3PO4 solution / acetonitrile (50 / 50, V / V).

[0047] Finally, the above solution was filtered through a 0.45 μm syringe filter and then injected into HPLC for detection. The mobile phase was 0.055 wt% H3PO4 solution / acetonitrile (50 / 50, V / V), with isocratic elution for 10 min and a mobile phase flow rate of 1 mL / min. –1 The injection volume was 10 μL, the column temperature was 30 ℃, and the wavelength of the ultraviolet detector was 255 nm.

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] Example 1 This embodiment provides a magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material, the preparation method of which includes the following steps: 1. Synthesis of Magnetic Reduced Graphene Oxide (MRGO) A. Weigh out 150 mg of graphene oxide (GO) and 400 mg of FeCl3. 6H2O, 150 mg trisodium citrate, 1.8 g sodium acetate and 1.0 g polyethylene glycol were placed in a centrifuge tube containing 40 mL ethylene glycol and subjected to sonication for 60 minutes and magnetic stirring for 60 minutes in sequence to obtain a uniformly dispersed suspension.

[0050] B. Transfer the suspension obtained in step A to a stainless steel high-pressure reactor lined with polytetrafluoroethylene and react at 200 °C for 12 hours.

[0051] C. After the stainless steel high-pressure reactor has cooled naturally to room temperature, the reaction product is collected using a magnet and washed with ethanol three times, 5 mL each time. Then the product is dried in a vacuum oven to obtain 200 mg of MRGO.

[0052] 2. Modifying the surface of MRGO with gold nanoparticles (AuNPs) A. Weigh 50 mg of MRGO and disperse it in 150 mL of ultrapure water. After sonicating for 5 minutes, transfer it to a three-necked round-bottom flask and place the flask in an ice-water bath. Stir the MRGO suspension mechanically for 20 minutes.

[0053] B. Add another 1.5 mL of 10 mg mL –1 HAuCl4 Add 3H2O solution and continue stirring for 1 hour until the gold ions and MRGO are fully mixed.

[0054] C. Then, over 2 minutes, while stirring, add 1.5 mL of freshly prepared 150 mmol solution dropwise to the flask. L –1 After the sodium borohydride solution is added dropwise, stir continuously for 15 minutes.

[0055] D. The product was then collected using a magnet, washed three times with 5 mL of ultrapure water each time, and dried in a vacuum oven to obtain 55 mg of magnetically reduced graphene oxide / gold nanoparticle composite material (MRGO@AuNPs).

[0056] 3. Grafting of n-octadecyl mercaptan (ODT).

[0057] A. Weigh 10 mg of MRGO@AuNPs into a centrifuge tube containing 10 mL of ethanol, and add 5 mL of 1 mmol... L – 1 ODT ethanol solution, the suspension in the centrifuge tube was shaken and mixed at room temperature for 12 hours.

[0058] B. The product was then collected using a magnet, washed three times with 5 mL of ethanol each time, and dried in a vacuum oven to obtain the magnetically reduced graphene oxide / hydrophobic gold nanoparticle composite material (MRGO@AuNPs-ODT).

[0059] The morphology of the synthesized MRGO and MRGO@AuNPs-ODT was characterized using transmission electron microscopy (TEM). The TEM image of MRGO is shown below. Figure 1 As shown in a (1 μm), 1b (500 nm), and 1c (100 nm), Fe3O4 particles with a size of approximately 200 nm are uniformly anchored on the two-dimensional graphene oxide nanosheets. TEM images of MRGO@AuNPs-ODT are shown below. Figure 1 As shown in d (1 μm), 1e (500 nm), and 1f (100 nm), MRGO is modified with AuNPs with a particle size of approximately 50 nm. Furthermore, the comparison reveals that the AuNPs are not uniformly spherical, but also exhibit irregular morphologies such as triangles and rods. The formation of these irregular morphologies is mainly attributed to the local concentration differences of HAuCl4 during the formation of MRGO@AuNPs, and the inducing effect of the oxygen-containing groups of graphene oxide on the anisotropic growth of the AuNPs crystals. Simultaneously, the irregular morphology of the AuNPs crystals, due to enhanced surface plasmon resonance, results in superior electrocatalytic activity, effectively improving the subsequent electrochemical DPV detection performance of CPZ.

[0060] Infrared spectroscopy was used to characterize and analyze the surface functional groups of GO, MRGO, MRGO@AuNPs, and MRGO@AuNPs-ODT, such as... Figure 2 As shown in a, after GO is prepared into MRGO via a solvothermal reaction, its oxygen-containing functional groups, such as hydroxyl groups (3400 cm), are... –1 ), carbonyl (1730 cm) –1 ) and epoxy groups (1051 cm –1 The absorption peak intensity of ) decreased, while the absorption peak of C=C bond (1630 cm⁻¹) remained weaker. –1 The presence of GO indicates that GO was reduced to reduced graphene oxide (RGO). Simultaneously, a new absorption peak (580 cm⁻¹) appeared in MRGO. –1 This peak is generated by the Fe–O–Fe vibration in Fe3O4, indicating that the Fe3O4 particles are anchored on the graphene oxide nanosheets. The characteristic absorption peaks of MRGO@AuNPs and MRGO are basically the same, except that the intensity of the Fe–O–Fe absorption peak is reduced. This is because the presence of AuNPs alters the local electron cloud density of Fe–O–Fe, resulting in decreased vibrational activity. In the infrared spectrum of MRGO@AuNPs-ODT, the peak at 2920 cm⁻¹... –1 and 2850 cm –1 The absorption peak at 1466 cm⁻¹ corresponds to the vibration of –CH₂– in the ODT molecule. –1 and 720 cm –1 The absorption peaks at these locations correspond to the bending and stretching vibrations of C–S, respectively, indicating that ODT is grafted onto AuNPs via gold-sulfur bonds.

[0061] Raman spectroscopy was used to characterize GO, MRGO, MRGO@AuNPs, and MRGO@AuNPs-ODT, such as... Figure 2 As shown in b, 1340 cm –1 and 1598 cm –1 The two peaks correspond to the D and G bands unique to carbon materials, respectively. The defect peak intensity (ID) / graphite peak intensity (IG) values ​​of GO, MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT are 1.16, 1.28, 1.21 and 1.33, respectively. The ID / IG value of MRGO@AuNPs-ODT did not increase significantly, indicating that the solvothermal reaction and nanoparticle modification did not significantly increase the defects on the surface of the carbon material. It can be used for detection by magnetic solid phase extraction-differential pulse voltammetry (MSPE-DPV).

[0062] X-ray diffraction (XRD) was used to characterize the crystal structure of the prepared materials, such as... Figure 3As shown in Figure a, GO exhibits a sharp diffraction peak at approximately 10°, which is a typical characteristic diffraction peak of GO sheets. MRGO shows a broad peak at 24° corresponding to the (002) crystal plane of RGO, and diffraction peaks at 30.1°, 35.2°, 43.1°, 53.6°, 56.8°, and 62.4° correspond to the (220), (311), (400), (422), (511), and (440) crystal planes of Fe3O4, respectively. The diffraction peaks have moderate intensity and sharp shape, indicating that well-crystallized Fe3O4 is anchored on MRGO nanosheets. Compared to MRGO, the XRD pattern of MRGO@AuNPs shows new diffraction peaks at 38.2°, 44.6°, 64.9°, and 77.6°, corresponding to the (111), (200), (220), and (311) crystal planes of AuNPs, respectively. This indicates that AuNPs have been modified onto the MRGO surface. The XRD pattern of MRGO@AuNPs-ODT shows no significant difference from that of MRGO@AuNPs, because ODT molecules are amorphous and do not produce XRD diffraction peaks.

[0063] The hysteresis loops of Fe3O4, MRGO, MRGO@AuNPs, and MRGO@AuNPs-ODT are as follows: Figure 3 As shown in b, its saturation magnetization is 63.8 emu·g. –1 44.7 emu·g –1 38.0 emu·g –1 and 34.8 emu·g –1 This indicates that MRGO@AuNPs-ODT can achieve rapid separation under an external magnetic field.

[0064] MRGO@AuNPs-ODT was analyzed using a nitrogen adsorption-desorption apparatus based on a specific surface area analysis (BET) model, and its specific surface area was found to be 67.6 m². 2 g –1 This indicates that the composite material has a large specific surface area and a two-dimensional sheet structure, which can provide abundant adsorption active sites, improve the adsorption performance of CPZ, and lay a structural foundation for the subsequent efficient separation and enrichment of CPZ.

[0065] Test Example 1 This test example provides a standard detection procedure for MRGO@AuNPs-ODT for chlorpromazine (CPZ), and the specific steps are as follows: 1. Weigh 1.5 mg of MRGO@AuNPs-ODT, mix it with 20 mL of CPZ solution, and vortex for 30 minutes.

[0066] 2. Immerse the cleaned MGCE in a mixture of MRGO@AuNPs-ODT and CPZ. Use the magnetic attraction of MGCE to attach the MRGO@AuNPs-ODT with adsorbed CPZ to the electrode surface of MGCE.

[0067] 3. Remove the MGCE and immerse it in an electrolytic cell for electrochemical differential pulse voltammetry (DPV) detection. The electrolyte solution in the electrolytic cell is 0.1 mol / L. L –1 The phosphate buffer solution (PBS, pH 7.0, containing 0.1 mol) L –1 (KCl), DPV scan potential range 0.2~1.0 V, potential increment 4 mV, pulse amplitude 50 mV.

[0068] Test Example 2 This test example is used to test the adsorption capacity of Fe3O4 and MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT in Example 1 for CPZ under the same experimental conditions.

[0069] The test method for MRGO@AuNPs-ODT is basically the same as that in Test Example 1, except that the concentration of the CPZ solution is 500 μmol·L⁻¹. –1 The volume was 0.5 mL, and the dosage of MRGO@AuNPs-ODT was 0.3 mg.

[0070] The testing methods for Fe3O4, MRGO, and MRGO@AuNPs are basically the same as those for MRGO@AuNPs-ODT, except that Fe3O4, MRGO, and MRGO@AuNPs are used instead of MRGO@AuNPs-ODT, respectively.

[0071] It should be noted that the adsorption capacity of CPZ was calculated by measuring the concentration of CPZ in the solution after adsorption using ultraviolet spectrophotometry, combined with the concentration and volume of the CPZ solution before adsorption.

[0072] Test results are as follows Figure 4 As shown, the adsorption capacity of Fe3O4 is 8.1 μg·mg. –1 The MRGO content was 33.7 μg·mg. –1 This is mainly due to the π-π interaction between the conjugated aromatic structure of reduced graphene oxide (RGO) and CPZ molecules in the material, which provides the fundamental driving force for the adsorption process. The adsorption capacity of MRGO@AuNPs for CPZ is 34.6 μg·mg. –1The adsorption capacity of MRGO@AuNPs showed no significant difference compared to that of MRGO, indicating that loading AuNPs did not contribute to the adsorption capacity of the material. However, after grafting ODT molecules onto the surface of MRGO@AuNPs, the adsorption capacity of the prepared MRGO@AuNPs-ODT for CPZ increased to 75.1 μg·mg. –1 The adsorption capacity of MRGO@AuNPs-ODT is about 1.2 times higher than that of MRGO@AuNPs. This change indicates that hydrophobic interactions are formed between the long-chain alkyl groups in the ODT molecule and the hydrophobic groups in the CPZ molecule, which further enhances the adsorption capacity of MRGO@AuNPs-ODT for CPZ.

[0073] Test Example 3 This test case is used to test the feasibility of using MRGO@AuNPs-ODT in Example 1 to determine CPZ using magnetic solid phase extraction-differential pulse voltammetry (MSPE-DPV).

[0074] The test method for MRGO@AuNPs-ODT is basically the same as that in Test Example 1, except that the concentration of the CPZ solution is 100 μmol·L⁻¹. –1 .

[0075] The testing methods for MRGO and MRGO@AuNPs in Example 1 are basically the same as those for MRGO@AuNPs-ODT, except that MRGO and MRGO@AuNPs are used instead of MRGO@AuNPs-ODT respectively.

[0076] In addition, a control test was conducted by directly immersing the cleaned MGCE in an electrolyte solution containing CPZ for electrochemical differential pulse voltammetry (DPV) detection. The concentration of CPZ was 100 μmol·L⁻¹. –1 The electrolyte solution and detection conditions were the same as in Test Example 1.

[0077] Specific test results are as follows: Figure 5 As shown.

[0078] from Figure 5 As can be seen, a significant CPZ oxidation peak is observed at 0.68 V in all DPV curves, indicating that CPZ underwent an oxidation reaction during the detection process.

[0079] Comparing the DPV spectra of CPZ directly detected by MGCE, it can be seen that after sequential separation and enrichment by MRGO, MRGO@AuNPs and MRGO@AuNPs-ODT, the corresponding CPZ peak currents are all enhanced, and the enhancement magnitude increases sequentially. Figure 5Curve c is the DPV curve after separation and enrichment by MRGO@AuNPs. Compared with curve b after separation and enrichment by MRGO, the peak current is significantly increased. Although the adsorption performance of MRGO@AuNPs and MRGO for CPZ is similar during the adsorption process, the introduction of AuNPs endows the material with excellent electrocatalytic activity, which can effectively amplify the electrochemical detection signal of CPZ. Curve d is the DPV curve after separation and enrichment by MRGO@AuNPs-ODT, with the largest oxidation peak current intensity, which corresponds to the characteristic of the composite material having the strongest adsorption capacity for CPZ. The above results indicate that the MRGO@AuNPs-ODT composite material can improve the detection sensitivity of CPZ through the synergistic effect of CPZ separation and enrichment and signal amplification.

[0080] Test Example 4 This test case is used to test the peak current of different concentrations of CPZ after separation and enrichment by MRGO@AuNPs-ODT in Example 1 using MSPE-DPV coupled technology, and to establish a standard curve.

[0081] The test method is basically the same as in Test Example 1, the only difference being the CPZ concentration, as shown in Figure 6b. Specific test results are as follows: Figure 6 As shown in Figure a, with the increase of CPZ concentration (0.1~200 μmol·L⁻¹), –1 As shown in the figure, the peak current at 0.68 V gradually increases.

[0082] A standard curve for the MSPE-DPV combined technology was constructed by plotting the peak current intensity at 0.68 V on the ordinate and the CPZ concentration on the abscissa, as shown below. Figure 6 As shown in figure b, it can be seen from the figure that the peak current is related to the CPZ concentration in the range of 0.1~8 μmol·L⁻¹. –1 and 8~200 μmol·L –1 The two intervals exhibit a good linear relationship, and the corresponding linear equations are I. p (μA)=0.881c CPZ (μmol·L –1 +0.346, R 2 =0.998 and I p (μA)=0.094c CPZ (μmol·L –1 +6.78, R 2 =0.994. Based on the results of 10 blank tests, the noise average of the MSPE-DPV coupled technology was calculated, and the detection limit (LOD) was obtained as 19 nmol·L⁻¹ based on a three-fold signal-to-noise ratio. –1 .

[0083] Test Example 5 This test case is used to test the anti-interference performance of MRGO@AuNPs-ODT in detecting CPZ using MSPE-DPV combined technology in Example 1.

[0084] 20 μmol·L –1 Excess interfering substances, such as 10 times the concentration of common ions (Na+), were added to the CPZ standard solutions. + K + NO3 - and SO4 2- ), 5 times the concentration of biomolecules (glucose Glu, glycine Gly and ascorbic acid AA), 5 times the concentration of common veterinary drugs (metronidazole Met, chloramphenicol Cap and acetaminophen Ace) and 5 times the concentration of the CPZ analog promethazine (PHZ).

[0085] 20 μmol·L –1 The CPZ standard solution and the above solutions were subjected to the test method of Test Example 1, and after separation and enrichment by MRGO@AuNPs-ODT, DPV was detected. The test results are as follows: Figure 7 As shown, the relative error of the obtained oxidation peak current compared with the CPZ standard solution without added interfering substances did not exceed ±10%, indicating that the MSPE-DPV method based on MRGO@AuNPs-ODT has good anti-interference performance for the determination of CPZ. More importantly, even for the CPZ analogue promethazine (PHZ), this demonstrates that the detection method can specifically identify chlorpromazine.

[0086] Test Example 6 This test case is used to test the storage stability of MRGO@AuNPs-ODT in Example 1.

[0087] The test procedure for this test case is basically the same as that for Test Case 1, the only difference being the use of 20 μmol·L⁻¹. –1 CPZ solution was used as the detection target, and MRGO@AuNPs-ODT solutions stored for 1 day, 3 days, 5 days, 7 days, 10 days, and 14 days were used for separation and enrichment.

[0088] Specific test results are as follows: Figure 8 As shown, the DPV peak current did not fluctuate significantly, indicating that MRGO@AuNPs-ODT has acceptable long-term stability in CPZ measurement applications.

[0089] Test Example 7 This test case is used to test the feasibility of using MSPE-DPV combined with MRGO@AuNPs-ODT for actual detection.

[0090] The test procedure for this test case is basically the same as that for Test Case 1, the only difference being the pre-treated beef and beef + 0.5 μmol·L⁻¹. –1 CPZ solution, beef + 1 μmol·L –1 CPZ solution, beef + 1.5 μmol·L –1 CPZ solution, sea bass, sea bass + 0.5 μmol·L⁻¹ –1 CPZ solution, sea bass + 1 μmol·L –1 CPZ solution, sea bass + 1.5 μmol·L⁻¹ –1 CPZ solution was used as the detection target, and MRGO@AuNPs-ODT was used to separate and enrich it.

[0091] The specific test results are shown in Table 1.

[0092] Test Example 8 This test case is used to test the actual detection effect of the HPLC method and compare it with the MSPE-DPV coupling technology based on MRGO@AuNPs-ODT.

[0093] This test case showed pre-treated beef and beef with 0.5 μmol·L⁻¹. –1 CPZ solution, beef + 1 μmol·L –1 CPZ solution, beef + 1.5 μmol·L –1 CPZ solution, sea bass, sea bass + 0.5 μmol·L⁻¹ –1 CPZ solution, sea bass + 1 μmol·L –1 CPZ solution, sea bass + 1.5 μmol·L⁻¹ –1 CPZ solution is the target of detection. The specific test results are shown in Table 1.

[0094] Table 1 Comparison of recoveries of MSPE-DPV method and HPLC method in actual sample detection

[0095] As shown in Table 1, in the recovery experiments of actual samples using the MSPE-DPV coupled technique, the recoveries of beef and sea bass samples ranged from 89.6% to 93.6%, with RSDs ranging from 4.6% to 8.7%. This indicates that the MSPE-DPV method still possesses good anti-interference ability and detection accuracy in complex food samples. Comparing this method with the HPLC method, the experiments showed that the HPLC method achieved recoveries of 87.6% to 92.5% in beef and sea bass samples, with RSDs ranging from 0.6% to 2.0%. The comparative results show that the recovery rate of this method is comparable to that of the HPLC method, and the sample pretreatment process is significantly simplified. Furthermore, this method offers advantages such as ease of operation, low reagent consumption, and short detection time, making it more suitable for rapid detection of CPZ.

[0096] Test Example 9 This test case is used to test the batch reproducibility of MRGO@AuNPs-ODT.

[0097] The MRGO@AuNPs-ODT prepared in Example 1 is designated as No. 1. The preparation process of Example 1 is repeated 7 times to obtain 7 batches of MRGO@AuNPs-ODT, which are designated as No. 2, 3, 4, 5, 6, 7, and 8, respectively.

[0098] The test procedure for this test case is basically the same as that for Test Case 1, the only difference being the use of 20 μmol·L⁻¹. –1 CPZ solution was used as the detection target, and MRGO@AuNPs-ODT was used in 8 batches to separate and enrich it.

[0099] Specific test results are as follows: Figure 9 As shown, the relative standard deviation (RSD) of the DPV peak current measured in each batch was 8.7%, which indicates that the composite material and the detection electrode have good batch reproducibility in CPZ measurement.

[0100] The above description provides an illustrative overview of the present invention and its embodiments. This description is not restrictive, and the embodiments shown are merely one example of the invention's implementation. Actual implementations are not limited to these examples. Therefore, if those skilled in the art are inspired by this description and design similar implementations and examples without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention.

Claims

1. A magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite, characterized by, The magnetic reduced graphene oxide is modified with gold nanoparticles on the nanosheet of the magnetic reduced graphene oxide, and the gold nanoparticles are grafted with n-octadecanethiol through gold-sulfur bond.

2. The magnetic reduced graphene oxide / hydrophobized gold nanoparticles composite according to claim 1, characterized in that, The particle size of the Fe3O4 particles is 100 nm-300 nm, and the particle size of the gold nanoparticles is 10 nm-100 nm. 3.The magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite of claim 1, wherein, The XRD pattern of the magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material has characteristic diffraction peaks at 2θ of 38.2±0.2°, 44.6±0.2°, 64.9±0.2° and 77.6±0.2°.

4. The magnetic reduced graphene oxide / hydrophobized gold nanoparticle composite of claim 1, wherein, The magnetic reduction of graphene oxide / hydrophobic gold nanoparticle composites has a magnetization intensity greater than 20 emu-g –1 .

5. The preparation method of the magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material according to any one of claims 1-4, comprising the following steps: S1, synthesizing magnetic reduced graphene oxide; S2, modifying gold nanoparticles on the nanosheet surface of the magnetic reduced graphene oxide; S3, the gold nanoparticles are grafted with n-octadecanethiol through gold-sulfur bond.

6. The production method according to claim 5, wherein The S2 comprises the following steps: S2.1 dispersing the magnetic reduced graphene oxide in ultrapure water, stirring at 0±5 ℃ for 10-30 min after ultrasonic treatment to obtain a magnetic reduced graphene oxide suspension, and the concentration of the magnetic reduced graphene oxide suspension is 0.2 mg / mL-0.5 mg / mL; S2.2 adding HAuCl4 solution to the magnetic reduced graphene oxide suspension, stirring for 0.5-2 h to obtain a mixed solution of magnetic reduced graphene oxide and HAuCl4, wherein the mass ratio of magnetic reduced graphene oxide to HAuCl4 is (3-5):1; S2.3 adding sodium borohydride solution drop by drop to the mixed solution of S2.2 while stirring for 1-5 min, and continuing to stir for 10-20 min after the dropwise addition is completed, wherein the mass ratio of magnetic reduced graphene oxide to sodium borohydride is (5-6.5):1; S2.4 collecting the solid product, washing with ultrapure water and drying in a vacuum oven to obtain a magnetic reduced graphene oxide / gold nanoparticle composite material.

7. The production method according to claim 6, characterized by, The S3 comprises the following steps: S3.1 placing the magnetic reduced graphene oxide / gold nanoparticle composite material in a centrifuge tube containing ethanol, then adding n-octadecanethiol ethanol solution, and oscillating and mixing for 10-14 h to obtain a suspension of magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material, wherein the mass ratio of magnetic reduced graphene oxide / gold nanoparticle composite material to n-octadecanethiol is (6-8):1; S3.2 collecting the solid product, washing with ethanol and drying in a vacuum oven to obtain a magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material.

8. The application of the magnetic reduced graphene oxide / hydrophobic gold nanoparticle composite material according to any one of claims 1-4 in the analysis of chlorpromazine.

9. Use according to claim 8, characterized in that, In the application, chlorpromazine is determined by using magnetic solid phase extraction-differential pulse voltammetry technology, comprising the following steps: M1, vortexing the magnetic reduced graphene oxide / hydrophobicized gold nanoparticle composite and the sample to be measured for 20-40 min to obtain a mixed solution; M2, immersing the magnetic glassy carbon electrode in the mixed solution in M1 to adsorb the magnetic reduced graphene oxide / hydrophobicized gold nanoparticle composite; M3, the magnetic glassy carbon electrode is immersed into the electrolytic cell to perform differential pulse voltammetry detection to obtain a differential pulse voltammetry curve, wherein the peak current intensity at 0.68 V is I p ; M4, the peak current intensity I p The standard curve of the detection of chlorpromazine by magnetic solid phase extraction-differential pulse voltammetry is substituted into the concentration of chlorpromazine, denoted as c CPZ .

10. Use according to claim 9, characterized in that, The standard curve is two-segmented: The concentration c of the chlorpromazine CPZ Located at 0.1~8 μmol·L –1 The peak current intensity I p The linear equation of the concentration c of the chlorpromazine CPZ ​ I p (μA)=0.881c CPZ (μmol·L –1 )+0.346; the concentration c of the chloφromazine CPZ greater than 8 μmol L –1 the peak current intensity I i with the concentration c of the chloφromazine CPZ is a linear equation I p (μA)=0.094c CPZ (μmol·L –1 )+6.78.

Images