An electrochemical sensor based on MNC single-atom catalyst and its application
By modifying a glassy carbon electrode with a single-atom MNC catalyst and combining it with differential pulse voltammetry, the problem of simultaneous detection of multiple phenolic compounds has been solved, achieving highly sensitive, rapid, and low-cost detection of phenolic compounds, which is applicable to the detection of phenolic compounds in water, plastic products, and food packaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-05-07
- Publication Date
- 2026-03-10
AI Technical Summary
Existing electrochemical sensors are difficult to achieve high sensitivity and rapid detection of multiple phenolic compounds simultaneously, especially for bisphenol compounds such as bisphenol AF, bisphenol S, and bisphenol AP. Furthermore, traditional detection methods involve complex sample pretreatment, high costs, and large equipment, making them unsuitable for on-site detection.
An electrochemical sensor was constructed using a glassy carbon electrode modified with a MNC single-atom catalyst and combined with differential pulse voltammetry. The high activity and selectivity of the MNC single-atom catalyst enabled the highly sensitive detection of a variety of phenolic compounds.
It achieves highly sensitive, rapid, and accurate detection of a variety of phenolic compounds, reduces detection costs, simplifies sample pretreatment, is suitable for field applications, and has good selectivity and reproducibility.
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Figure CN117054498B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical sensor and analytical chemistry technology, and in particular relates to an electrochemical sensor based on a MNC single-atom catalyst that can be applied to the rapid detection of a variety of phenolic compounds simultaneously. Background Technology
[0002] Phenolic compounds (monohydric and polyhydric phenols) are among the most important endocrine disruptors, and their rapid screening and detection have become a research hotspot in the environmental field. Monohydric phenols such as phenol and polyhydric phenols such as bisphenols have been extensively studied due to their wide distribution and high toxicity. A series of structural analogs, such as bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol Z, bisphenol AP, bisphenol AF, and bisphenol S, not only have similar structures but also similar acute toxicity, genotoxicity, and estrogenic effects, constantly endangering human physical and mental health, especially infants and pregnant women. Currently, many countries have successively introduced laws and regulations prohibiting or restricting the use of bisphenol compounds. Therefore, highly sensitive and rapid detection of these phenolic compounds has become a research hotspot in recent years.
[0003] To meet the demand for phenolic compound detection, there is an urgent need to develop reliable, efficient, sensitive, rapid, and inexpensive analytical detection methods. Traditional detection methods, such as high-performance liquid chromatography (HPLC), mass spectrometry (MS), and liquid chromatography-mass spectrometry (LC-MS), are mainly based on precision instruments and suffer from drawbacks such as complex and time-consuming sample pretreatment, expensive and bulky equipment, high technical requirements for operators, high detection costs, and unsuitability for on-site real-time detection. Electrochemical detection methods, with their advantages of ease of operation and high sensitivity, are widely used for highly sensitive and rapid detection of phenolic compounds. Among them, electrochemical tyrosinase sensors, as an emerging analytical detection method, can achieve highly sensitive and rapid detection of phenolic compounds using the time-current method. However, they cannot achieve simultaneous detection of multiple analytes, and the sensor does not respond to some bisphenol compounds (such as bisphenol AF, bisphenol S, and bisphenol AP). Therefore, there is an urgent need to develop new electrochemical detection methods to achieve highly sensitive and rapid simultaneous detection of multiple phenolic compounds.
[0004] The electrochemical sensor is fabricated using a glassy carbon electrode modified with a novel material possessing unique physical and chemical properties as the working electrode. This sensor utilizes the substrate electrode to convert chemical signals into electrical signals and leverages the signal amplification effect of the modified material to achieve highly sensitive detection of the analyte. The main advantages of this electrochemical sensor include: 1. High response sensitivity and fast detection speed; 2. Good selectivity; 3. Simple operation and low cost; 4. Easy miniaturization, suitable for on-site detection and continuous online monitoring.
[0005] To further improve the detection performance of electrochemical sensors, the selection of electrode modification materials is crucial. In recent years, single-atom catalysts have attracted increasing attention due to their unique structure, exhibiting significantly different activity, stability, and selectivity compared to conventional nanocatalysts. Single-atom catalysts consist of metals uniformly distributed on a support in the form of single atoms, resulting in extremely low metal loading and greatly improved metal atom utilization efficiency and catalytic activity. Single-atom catalysts possess many novel properties, such as dramatically increased surface free energy, quantum size effects, unsaturated coordination environments, and metal-support interactions, giving them superior catalytic performance. They have become a research hotspot in the materials science field in recent years and have broad application prospects in areas such as water catalysis, hydrocarbon chemistry, energy storage batteries, biomedicine, and chemical sensors.
[0006] To date, there have been no reports, either domestically or internationally, of electrochemical sensors based on single-atom catalysts, especially MNC single-atom catalysts, for the simultaneous rapid detection of multiple phenolic compounds. This invention aims to comprehensively utilize the signal amplification effect of nanomaterials, surface modification techniques, and electrochemical sensing technology to construct an electrochemical sensor with high sensitivity, rapid response, good specificity, and low cost capable of simultaneously and rapidly detecting multiple phenolic compounds, effectively addressing the shortcomings of current phenolic compound detection methods. Summary of the Invention
[0007] Based on the above background technology, the purpose of this invention is to provide an electrochemical sensor for the highly sensitive and rapid simultaneous detection of multiple phenolic compounds. This sensor is simple to operate, has a fast response speed, high sensitivity, low detection limit, and is inexpensive. It can be directly used for the simultaneous detection of multiple phenolic compounds in water samples, and can also be used for the detection of phenolic compounds in plastic products, food packaging, and beverage bottles. This invention provides an electrochemical sensor based on a MNC single-atom catalyst. This sensor has advantages such as good selectivity, high sensitivity, low detection limit, low cost, simple preparation method, and reliable and portable equipment. Furthermore, it can achieve the simultaneous detection of one or more phenolic compounds and can be used for on-site screening and detection of environmental pollutants, especially phenolic compounds in water.
[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0009] This invention provides an electrochemical sensor for the simultaneous detection of multiple phenolic compounds, wherein the electrode modification material of the electrochemical sensor is a single-atom catalyst. The single-atom catalyst is an MNC single-atom catalyst. The metal active center M is partially or completely dispersed as isolated single atoms on the surface of a nitrogen-doped carbon material (NC); M includes, but is not limited to, one or more of alkali metal single atoms (such as Li, Na, K), alkaline earth metal single atoms (such as Mg, Ca, Sr), and transition metal single atoms (such as Fe, Co, Ni, Cu); nitrogen is covalently doped onto the nitrogen-doped carbon material, wherein N includes, but is not limited to, one or more of pyridine nitrogen, pyrrole nitrogen, graphitic nitrogen, and pyrimidine nitrogen; C is a carbon-based support; wherein the mass content of nitrogen in the nitrogen-doped carbon material is 0.1-20%, preferably 1-12%; and the loading of M is 0.1-9%.
[0010] The MNC single-atom catalysts described in this invention include, but are not limited to, alkali metal single-atom catalysts, alkaline earth metal single-atom catalysts, and transition metal single-atom catalysts.
[0011] Preferably, the MNC single-atom catalyst is an alkali metal single-atom catalyst or an alkaline earth metal single-atom catalyst, and more preferably a MgNC single-atom catalyst.
[0012] The present invention also provides a method for preparing the above-mentioned electrochemical sensor, comprising the following steps:
[0013] (1) The MNC single-atom catalyst was ultrasonically dispersed in an aqueous phase to obtain a dispersion system with a concentration of 1-5 mg / mL.
[0014] (2) Add the film-forming material to the dispersion system and mix thoroughly to obtain a mixed solution;
[0015] In the mixed solution: the concentration of MNC single-atom catalyst is 0.5–3 mg / mL, and the concentration of film-forming material is 0.1–2.0 mg / mL;
[0016] (3) The mixed solution (e.g., 3-8 μL) is added dropwise to the surface of the glassy carbon electrode, and allowed to stand and dry at room temperature to obtain the electrochemical sensor.
[0017] Based on the above technical solutions, the film-forming material includes, but is not limited to, at least one of chitosan, Nafion, glutaraldehyde, etc.
[0018] Preferably, the film-forming material is chitosan, which is a linear polymer obtained from crab shells and / or shrimp shells, and its degree of deacetylation is 75% to 85%.
[0019] Preferably, the polishing process of the glassy carbon electrode surface is as follows: the glassy carbon electrode surface is polished sequentially with one or more of aluminum oxide powders with particle sizes of 1μm, 0.3μm and 0.05μm, then ultrasonically cleaned repeatedly in anhydrous ethanol and deionized water, and finally dried with high-purity nitrogen gas for later use.
[0020] The present invention also provides applications of the above-described electrochemical sensor or the electrochemical sensor obtained by the above preparation method for detecting phenolic compounds in water environment samples, plastic products, and food contact materials (food packaging materials and beverage bottles).
[0021] Preferably, the application uses a standard curve obtained by measuring the relationship between the response current intensity detected by the electrochemical sensor and the concentration of the phenolic target compound to determine whether the sample contains phenolic compounds and simultaneously determine the concentration of phenolic compounds; and uses the difference in oxidation peak potential in the differential pulse voltammetry curve to determine the type of phenolic compounds in the sample.
[0022] Based on the above technical solution, the detection includes the following steps: immersing the electrochemical sensor as the working electrode, the Ag / AgCl reference electrode, and the Pt electrode into a detection solution containing phenolic compounds, performing differential pulse voltammetry scanning, and recording the response current signal.
[0023] Preferably, the scanning potential range of the differential pulse voltammetry is -0.2 to 1.4 V, the enrichment potential is 0.1 to 0.6 V, and the enrichment time is 60 to 240 s.
[0024] Preferably, the detection solution is a buffer salt solution, which includes, but is not limited to, at least one of phosphate buffer solution, acetate buffer solution, borate buffer solution, and citrate buffer solution, and has a pH value of 3 to 9.
[0025] Preferably, the phenolic compound includes at least one of phenol, catechol, bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF), bisphenol E (BPE), bisphenol Z (BPZ), bisphenol AP (AP), bisphenol S (BPS), and bisphenol AF (BPAF).
[0026] Preferably, the difference in oxidation peak potentials of two or more phenolic compounds that can be detected simultaneously is greater than or equal to 0.05V.
[0027] Preferably, the type of phenolic compound in the sample is determined by the position of the oxidation peak potential in the differential pulse voltammetry curve; and the presence and concentration of phenolic compounds in the sample are determined by a standard curve obtained by the relationship between the detected peak current intensity and the corresponding phenolic compound concentration.
[0028] Preferably, the detection includes the following steps: inserting the electrochemical sensor as a working electrode, an Ag / AgCl reference electrode, and a Pt electrode into a blank detection solution; adding one or more phenolic compounds of known concentration as target analytes into the detection solution; and simultaneously performing differential pulse voltammetry scanning and recording the voltammetric curve of the response.
[0029] Since the concentration of phenolic compounds in the detection solution can be known from different voltammetric curves, the concentration of phenolic compounds in the sample can be calculated and analyzed by forming a calibration curve with the current response signal I and the concentration C of the phenolic target analyte. Based on the different oxidation peak potentials, the types of phenolic compounds can be determined.
[0030] The electrochemical sensor of this invention is prepared by modifying the surface of a glassy carbon electrode with a composite material consisting of a mixture of a single-atom MNC catalyst and a film-forming material. This invention fully utilizes the superior properties of the novel electrode modification material, the single-atom MNC catalyst, such as its activity, high stability, and selectivity compared to conventional nanocatalysts, high metal atom utilization efficiency and catalytic efficiency, large specific surface area, and good aqueous phase dispersibility, achieving highly sensitive and rapid simultaneous detection of various phenolic compounds.
[0031] The beneficial effects of this invention are as follows:
[0032] (1) Single-atom catalysts reach the limit of metal dispersion, with each individual atom being an active site, maximizing atom utilization and greatly improving catalytic efficiency. Single-atom catalysts also have a large specific surface area, providing a large number of active sites for the attachment of catalytic substrates and enabling the enrichment of phenolic compounds; moreover, the high atom utilization and catalytic efficiency of single-atom catalysts greatly improve the detection sensitivity and detection limit of the sensor.
[0033] (2) Chitosan is a linear homopolymer with good film-forming ability and biocompatibility.
[0034] (3) Single-atom catalysts have good aqueous phase dispersibility, which can improve the reproducibility and detection limit of the sensor.
[0035] (4) The prepared electrochemical sensor is simple to prepare, inexpensive, requires no complicated sample pretreatment, is easy to operate, has a fast response speed, high sensitivity, low detection limit, good selectivity, wide applicability, is easy to miniaturize, is portable, and is suitable for on-site detection.
[0036] (5) The electrochemical sensor prepared by this invention has high sensitivity for the rapid detection of phenolic compounds in environmental samples, especially actual environmental water samples, plastic products, food packaging materials and beverage bottles. It can simultaneously, rapidly, accurately and efficiently evaluate the concentration levels of multiple phenolic compounds in actual samples. Compared with conventional chromatography-mass spectrometry, it has the advantages of simple sample pretreatment, fast detection speed, low cost and reliable and portable equipment. Attached Figure Description
[0037] Figure 1 This is a transmission electron microscope (TEM) image of the single-atom catalyst in Example 1 of the present invention;
[0038] Figure 2 This is a high-angle annular dark-field-scanning transmission electron microscope (HAAD-STEM) image of the single-atom catalyst in Example 1 of the present invention.
[0039] Figure 3 This is the X-ray diffraction (XRD) pattern of the single-atom catalyst in Example 1 of the present invention;
[0040] Figure 4 The differential pulse voltammetry curves for detecting bisphenol A using different metal single-atom catalysts in Example 3 of this invention are shown.
[0041] Figure 5 This is a graph showing the effect of different pH values on the sensor detection performance in Example 4 of the present invention.
[0042] Figure 6 This is a voltammetric curve of two phenolic compounds simultaneously detected by a bare electrode and a single-atom catalyst-modified electrode in Example 5 of the present invention.
[0043] Figure 7A The voltammetry and current-concentration linear correlation curves for the simultaneous detection of two bisphenol compounds (bisphenol A + bisphenol AF) in Example 6 of this invention are shown (with the concentration of bisphenol AF fixed at 5 μM).
[0044] Figure 7B The voltammetry and current-concentration linear correlation curves for the simultaneous detection of two bisphenol compounds (bisphenol A + bisphenol AF) in Example 6 of this invention are shown (with the concentration of bisphenol A fixed at 2 μM). Detailed Implementation
[0045] The following examples are used to illustrate the present invention, but do not limit the scope of the invention.
[0046] The specific steps for preparing the electrochemical sensor and detecting the sample are as follows:
[0047] (a) After mixing the MNC single-atom catalyst with water, the mixture was pretreated by ultrasound to obtain a dispersion system;
[0048] (b) Dissolve chitosan (75% degree of deacetylation) in 1% acetic acid solution to obtain chitosan solution;
[0049] (c) Mix the chitosan solution with the MNC single-atom catalyst dispersion, take 5 μL of the above composite solution containing MNC single-atom catalyst-chitosan (MNC-Chi) and drop it onto the surface of the polished glassy carbon electrode, let it stand and dry at room temperature to obtain the electrochemical sensor.
[0050] (d) Using the electrochemical sensor as the working electrode, a silver / silver chloride electrode as the reference electrode, and a platinum electrode as the auxiliary electrode, an electrochemical detection three-electrode system is constructed. Phosphate buffer solution is used as the detection solution, and differential pulse voltammetry is used as the detection method to detect the type and content of the phenolic compound to be tested.
[0051] The following are some of the instruments and equipment used in the embodiments of the present invention. Other experimental conditions not specifically mentioned shall be in accordance with conventional or instrument manufacturer's recommendations.
[0052] The instrument used for electrochemical detection was the Shanghai Chenhua electrochemical workstation CHI440, and the instrument used for electrochemical impedance spectroscopy was the Swiss Metrohm Autolab electrochemical workstation PGSTAT302N.
[0053] Example 1
[0054] Preparation and characterization of MgNC single-atom catalysts
[0055] Preparation of MgNC single-atom catalyst: 205.9 mg of magnesium acetate and 960 mg of the nitrogen-containing organic ligand o-phenanthroline were dissolved in 150 mL of anhydrous ethanol, and then 9.6 g of nano-magnesium oxide (50 nm) was added. After stirring in a water bath at 60 °C for 12 hours, the mixture was dried. Further calcination at 500 °C in nitrogen for 2 hours, followed by acid washing (2 mol / L nitric acid solution) and drying, yielded the MgNC material, in which the mass content of Mg was 0.48%, the mass content of N was 10.35%, the mass content of C was 81.98%, and the mass content of O was 7.19%.
[0056] The morphology and structure of the MgNC single-atom catalyst were characterized by transmission electron microscopy (TEM, HAAD-STEM) and X-ray diffraction (XRD). Figure 1 The TEM image shows that the prepared MgNC single-atom catalyst has a typical two-dimensional plate-like morphology and no large-scale aggregation of Mg particles. Figure 2 The image shown is from HAAD-STEM, where bright metallic Mg single atoms are uniformly dispersed on the carbon support surface, without Mg clusters. This is consistent with... Figure 3The XRD pattern showed only one broad C diffraction peak that matched the pattern, further confirming the single-atom dispersion of Mg.
[0057] Example 2
[0058] Fabrication of electrochemical sensor (MgNC-Chi / GCE)
[0059] Glassy carbon electrode assembly steps:
[0060] (a) The glassy carbon electrode surface was polished sequentially with aluminum oxide powders of 1 μm, 0.3 μm, and 0.05 μm particle sizes. It was then repeatedly ultrasonically cleaned in anhydrous ethanol and deionized water, and finally dried with high-purity nitrogen. The electrode was then placed in a 1 mmol / L potassium ferrocyanide / potassium ferrocyanide solution (molar ratio 1:1), and cyclic voltammetry was scanned between -0.1 and +0.6 V. The redox peak potential difference was less than 70 mV, indicating that the redox reaction on the glassy carbon electrode surface was completely reversible, the electrode polishing was good, and the next experimental step could be performed.
[0061] (b) Construction of the electrochemical sensor: The MgNC single-atom catalyst was mixed with water and pretreated by ultrasound to obtain a MgNC single-atom catalyst dispersion with a concentration of 2 mg / mL. Chitosan was dissolved in 1% acetic acid solution to obtain a chitosan solution with a concentration of 2 mg / mL. The chitosan solution and the MgNC single-atom catalyst dispersion were mixed at a volume ratio of 1:3 to obtain a final mixture with the following composition: MgNC single-atom catalyst concentration of 1.5 mg / mL and chitosan concentration of 0.5 mg / mL. 5 μL of the final composite solution was dropped onto the surface of a newly polished glassy carbon electrode, allowed to stand at room temperature, and slowly dried to obtain a homogeneous MgNC single-atom catalyst-chitosan electrode (MgNC-Chi / GCE).
[0062] (c) Before use, the modified glassy carbon electrode was immersed in 50 mmol / L phosphate buffer (pH=7.0) for 0.5 hours to remove any material that was not fixed to the electrode surface.
[0063] Example 3
[0064] Comparative Experiments: Potassium acetate, cobalt acetate, nickel acetate, and copper acetate were used instead of magnesium acetate in Example 1, and KNC, CoNC, NiNC, and CuNC single-atom catalysts were prepared using the same method as MgNC in Example 1. Following the method in Example 1, 960 mg of o-phenanthroline monohydrate was dissolved in 150 mL of anhydrous ethanol, and 9.6 g of nano-magnesium oxide (50 nm) was added. After stirring in a water bath at 60 °C for 12 hours, the mixture was dried, further calcined at 500 °C in nitrogen for 2 hours, washed with acid (2 mol / L nitric acid solution), and dried again to obtain the NC material. Electrochemical sensors (NC-Chi / GCE, KNC-Chi / GCE, CoNC-Chi / GCE, NiNC-Chi / GCE, and CuNC-Chi / GCE) were constructed using the NC (metal-free active center M), KNC, MgNC, CoNC, NiNC, and CuNC single-atom catalysts as electrode modification materials, respectively, using the method in Example 2. These were compared with the MgNC-Chi / GCE prepared in Example 2. Bisphenol A was enriched at an enrichment potential of 0.5 V and an enrichment time of 210 s. Then, 10 μM bisphenol A in 50 mmol / L phosphate buffer (pH = 7.0) was detected using differential pulse voltammetry within a potential range of 0.2–1.4 V. The results are as follows: Figure 4 As shown, the response signals of sensors detecting bisphenol A for different single-atom catalysts, from largest to smallest, are MgNC > KNC > NC ≈ CoNC > NiNC > CuNC. Alkali metal and alkaline earth metal single-atom catalysts have higher response signals and are superior to the support NC, indicating that alkali metal and alkaline earth metal single-atom catalysts have significantly better catalytic activity than transition metal single-atom catalysts in the catalytic oxidation of bisphenol A.
[0065] Example 4
[0066] pH range suitable for electrochemical sensors (MgNC-Chi / GCE)
[0067] Using the modified glassy carbon electrode prepared in Example 2 as the working electrode, the Ag / AgCl electrode as the reference electrode, and the Pt electrode as the auxiliary electrode, a three-electrode system was formed. The detection solution was a 50 mM phosphate buffer solution with pH values of 3, 5, 7, 9, and 11. 10 μM bisphenol A, bisphenol AF, and bisphenol S were added to the detection solution, respectively. The bisphenol compounds were enriched at an enrichment potential of 0.5 V and an enrichment time of 210 s. Differential pulse voltammetry was then used to perform differential pulse voltammetry scans within a potential range of 0.2–1.4 V, and the peak current and peak potential versus pH curves were recorded. Figure 5(Taking bisphenol A as an example). As can be seen from the figure, the electrochemical sensor developed in this invention has a high electrochemical response signal in detection solutions with pH values lower than its dissociation constant (pKa = 9.73), and is applicable in the pH range of 3 to 9, with a wide range of applications.
[0068] Example 5
[0069] Comparison of detection performance between MgNC-Chi / GC electrode and bare electrode
[0070] Using the glassy carbon electrode modified with the MgNC single-atom catalyst prepared in Example 2 and the bare glassy carbon electrode as working electrodes, two known concentrations of bisphenol compounds (5 μM bisphenol A + 5 μM bisphenol AF, 5 μM bisphenol A + 5 μM bisphenol S, 5 μM bisphenol AF + 4 μM bisphenol S) in a phosphate buffer solution at pH 7 were simultaneously detected. The bisphenol compounds were enriched at an enrichment potential of 0.5 V and an enrichment time of 210 s. Differential pulse voltammetry was then used to perform differential pulse voltammetry scans within a potential range of 0.2–1.4 V, and the electrochemical response signals were recorded and compared. Figure 6 As shown, the sensitivity for simultaneous detection of any two bisphenol compounds is higher with the MgNC-Chi / GC electrode than with the bare electrode, indicating that the electrochemical sensor of this invention has high response sensitivity and that MgNC has high catalytic activity. Furthermore, the MgNC-Chi / GC electrode also exhibits superior peak resolution, especially when simultaneously detecting bisphenol S and bisphenol AF. On the bare electrode, the oxidation peaks of these two bisphenol compounds completely overlap, meaning that the total amount of both bisphenol compounds is actually detected. However, the differential pulse voltammetry curve of the MgNC-Chi / GC electrode shows two oxidation peaks, indicating that the electrochemical sensor of this invention can achieve highly sensitive and rapid simultaneous detection of two phenolic compounds with high selectivity.
[0071] Example 6
[0072] Electrochemical Sensor (MgNC-Chi / GCE) for Detection of Standard Solutions of Phenolic Compounds and Practical Applications
[0073] In Example 2, the MgNC single-atom catalyst-chitosan electrochemical sensor was prepared in a detection solution at pH 7. The concentration of one phenolic compound was fixed, while the concentration of another phenolic compound was varied. The electrochemical response signal was recorded, and a standard curve was plotted. Bisphenol A and bisphenol AF were used as examples.
[0074] Using 5 mL of phosphate buffer solution as the detection solution, the concentration of bisphenol AF was fixed at 5 μM, while the concentration of bisphenol A standard solution was varied (0.2–10 μM). Differential pulse voltammetry was performed at the optimal enrichment time (210 s) and enrichment potential (0.5 V) to obtain the voltammetric curves (Figure 7, A). Then, with the concentration of bisphenol A fixed at 2 μM, differential pulse voltammetric curves of bisphenol AF at different concentrations were measured (Figure 7, B). Based on the response current of the phenolic compound on each voltammetric curve and the known concentration, the correlation curve between the current intensity and the concentration of the phenolic compound was obtained (built-in graph). Simultaneous detection of bisphenol A and bisphenol AF showed good linearity, with detection limits of 0.506 μM and 1.011 μM, respectively.
[0075] Furthermore, using the same method, with the concentration of bisphenol S fixed at 5 μM, differential pulse voltammetry curves of bisphenol A at different concentrations were measured; then, with the concentration of bisphenol A fixed at 4 μM, differential pulse voltammetry curves of bisphenol S at different concentrations were measured, and correlation curves between current intensity and phenolic compound concentration were plotted. Simultaneous detection of bisphenol S and bisphenol A showed good linearity, with detection limits of 0.583 μM and 0.518 μM, respectively.
[0076] A fixed concentration ratio of bisphenol AF and bisphenol S of 5:4 was used. A certain volume of mixed standard solution was added according to this ratio. Differential pulse voltammetry was performed at the optimal enrichment time and enrichment potential to obtain voltammetric curves. Based on the response current of the phenolic compound on each voltammetric curve and its known concentration, correlation curves between current intensity and phenolic compound concentration were obtained. When bisphenol S and bisphenol AF were detected simultaneously, their detection limits were 0.952 μM and 1.158 μM, respectively.
[0077] When both bisphenol compounds were detected simultaneously, they exhibited good linearity, low detection limits, high sensitivity, and a wide linear range, indicating that the MgNC-based sensor can meet the requirement of highly sensitive and rapid simultaneous detection of one or more phenolic compounds.
[0078] Actual sample testing: Three different types of plastic bottles (PP, PC, and PET) were cut into 1cm × 1cm pieces, immersed in deionized water, and pretreated at 80℃ for 24 hours. After filtration, volume adjustment, and spiking, the differential pulse voltammetry method was used for electrochemical scanning, and the response current was recorded to analyze the types and contents of bisphenol compounds in the leachate. The results showed that no phenolic compounds were detected in the plastic products. Furthermore, good recoveries were obtained in the spiking detection (BPA: 73.15-103.12%, BPAF: 74.84-103.48%, BPS: 79.52-99.91%), indicating that this method has certain feasibility in practical applications.
[0079] Example 7
[0080] Evaluation of the anti-interference ability, reproducibility and stability of electrochemical sensors based on MgNC single-atom catalysts
[0081] At a concentration of 5 μM for bisphenol A, bisphenol S, and bisphenol AF, 50 μM of glucose, ascorbic acid, and catechol, respectively, were added to the detection solution as interfering agents. The bisphenol compounds were enriched at an enrichment potential of 0.5 V and an enrichment time of 210 s. Differential pulse voltammetry was then used to perform a differential pulse voltammetry scan within a potential range of 0.2–1.4 V to obtain electrochemical voltammetric curves in the presence of the three interfering agents. The results show that the presence of 10 times the amount of interfering agents does not affect the detection of bisphenol A, bisphenol S, and bisphenol AF by the electrochemical sensor prepared in Example 2. The same process was applied to 50 μM inorganic salt ions (Ni... 2+ Zn 2+ Co 2+ NO3 - SO4 2- Cl - The interference of the inorganic salt ions was tested, and the results showed that the inorganic salt ions had no interference effect on the electrochemical sensor of the present invention.
[0082] The reproducibility of the sensors was studied using differential pulse voltammetry. The relative standard deviations (RSDs) for the detection of 5 μM bisphenol A, bisphenol S, and bisphenol AF by the seven different electrochemical sensors prepared in Example 2 were 2.7%, 3.1%, and 4.6%, respectively, indicating good reproducibility among different electrodes. Furthermore, the electrochemical sensor prepared in Example 2 retained 88.2% of its original catalytic activity after being stored at 4°C for 3 weeks, demonstrating high storage stability.
[0083] The advantages of this invention are: 1. High sensitivity for detecting phenolic compounds; 2. Low detection limit; 3. Good selectivity; 4. Good peak separation, enabling simultaneous rapid detection of multiple phenolic compounds; 5. Wide applicability; 6. The sensor of this invention has advantages such as simple preparation process, no need for complex and time-consuming sample pretreatment, and easy miniaturization.
Claims
1. An electrochemical sensor for simultaneous detection of a plurality of phenolic compounds, characterized in that, The electrode modification material of the electrochemical sensor is a single-atom catalyst; the single-atom catalyst is MgNC single-atom catalyst, wherein the preparation method of the electrochemical sensor comprises: (1) Preparation of MgNC single-atom catalyst: magnesium acetate and nitrogen-containing organic ligand phenanthroline are dissolved in anhydrous ethanol, and then nano-magnesium oxide is added, and after stirring in a 60 °C water bath for 12 hours, drying, calcination at 500 °C for 2 hours in nitrogen, acid washing with nitric acid solution, and drying, the MgNC material is obtained; (2) Construction of electrochemical sensor: after mixing the MgNC single-atom catalyst with water and ultrasonic pretreatment, a MgNC single-atom catalyst dispersion liquid is obtained; chitosan is dissolved in a 1% acetic acid solution to obtain a chitosan solution; the chitosan solution and the MgNC single-atom catalyst dispersion liquid are mixed to obtain a final mixed liquid; the final mixed liquid is dropped onto the surface of a newly polished glassy carbon electrode, and after standing at room temperature and drying, a MgNC single-atom catalyst-chitosan electrode MgNC-Chi / GCE is obtained.
2. Use of an electrochemical sensor according to claim 1, characterized in that The electrochemical sensor can be used for simultaneous detection of one or more phenolic compounds in water environmental samples, plastic products and food contact materials.
3. Use according to claim 2, characterized in that: A three-electrode system composed of the electrochemical sensor, an Ag / AgCl reference electrode and a Pt electrode is immersed in a detection solution containing phenolic compounds, differential pulse voltammetry scanning is performed, and the response current signal is recorded; the scanning potential range of the differential pulse voltammetry method is-0.2-1.4 V, the enrichment potential is 0.1-0.6 V, and the enrichment time is 60-240 s.
4. Use according to claim 3, characterized in that, The detection solution is a buffer salt solution, and the buffer salt solution comprises at least one of a phosphate buffer solution, an acetate buffer solution, a borate buffer solution and a citrate buffer solution, and the pH value is 3-9.
5. Use according to claim 3, characterized in that: The phenolic compounds include at least one of phenol, catechol, bisphenol A, bisphenol B, bisphenol E, bisphenol F, bisphenol Z, bisphenol S, bisphenol AF and bisphenol AP.
6. Use according to claim 3, characterized in that, Two or more phenolic compounds can be simultaneously detected, and the difference between the oxidation peak potentials of the simultaneously detectable phenolic compounds is greater than or equal to 0.05 V.
7. Use according to claim 3, characterized in that, The type of phenolic compound in the sample is determined by the position of the oxidation peak potential in the differential pulse voltammetry curve, and whether the sample contains phenolic compounds and the concentration of the phenolic compounds are determined by a standard curve obtained by the relationship between the detected peak current intensity and the concentration of the corresponding phenolic compound.