A composite electrode for detecting paracetamol, its preparation and application

Abstract

The present invention discloses a composite electrode for detecting acetaminophen, its preparation method and application, belonging to the technical field of electrochemical sensors. The preparation method includes the following steps: (1) Pretreatment of GF; (2) Preparation of Co-Ce precursor / GF; (3) Preparation of Co-CeO2 NSs / GF composite electrode. The present invention also discloses the composite electrode prepared by the above preparation method, and the application of the composite electrode in an electrochemical sensor for detecting acetaminophen. The Co-CeO2 NSs / GF composite electrode provided by the present invention can detect ACOP in a neutral medium and at a low potential, and exhibits advantages such as good detection sensitivity, cyclic stability, anti-interference ability and high real sample recovery rate. The present invention can achieve efficient detection of ACOP, providing a feasible idea for the electrochemical detection of ACOP.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical sensors, and particularly to a composite electrode for detecting acetaminophen, its preparation and application. Background Art

[0002] Acetaminophen (ACOP) is an aniline non-steroidal anti-inflammatory drug, which has antipyretic, analgesic, anti-inflammatory and other effects, and can be used to treat and relieve various diseases such as cold fever, arthritis and various pains. However, if ACOP is used improperly, for a long time or in excess, it will cause various adverse reactions such as dermatitis and rash, gastrointestinal discomfort, nervous system damage and liver and kidney function damage. In severe cases, it may even cause acute liver and kidney failure and then death.

[0003] At present, the analytical technical means for detecting the content of ACOP include ultraviolet-visible spectrophotometry, fluorescence spectrometry, chemiluminescence, chromatography-mass spectrometry, capillary electrophoresis and electrochemical methods, etc. Among them, the electrochemical method has the advantages of low equipment cost, simple instrument operation, simple sample pretreatment, high detection efficiency, high sensitivity, low detection limit and good selectivity, so it has received wide attention and been applied in the field of analytical detection. However, in the prior art, there are still few electrochemical methods that can sensitively detect acetaminophen.

[0004] Therefore, how to provide an electrochemical detection method or electrochemical sensor for acetaminophen with high sensitivity and high detection efficiency is a technical problem that those skilled in the art need to solve urgently. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite electrode for detecting acetaminophen, its preparation and application to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the present invention provides the following scheme:

[0007] A preparation method of a composite electrode for detecting acetaminophen, comprising the following steps:

[0008] (1) Pretreat the graphite felt (GF) to obtain the pretreated GF;

[0009] (2) Immerse the pretreated GF into a cobalt-cerium precursor solution to prepare Co-Ce precursor / GF;

[0010] (3) Heat-treat the Co-Ce precursor / GF to prepare Co-CeO 2 NSs / GF composite electrode.

[0011] Advantageous Effects: Cerium dioxide (CeO 2)The base material has high surface oxygen migration rate, chemical stability, thermal stability, biocompatibility, non-toxicity, and excellent redox ability due to the valence variability between Ce 3+ / Ce 4+ etc. When applied to electrochemical sensors, it is often necessary to modify or process the CeO 2 material to change its chemical composition or morphological structure and further improve its application performance. Generally speaking, vacancy defects play an important role in the performance of metal oxide materials, and oxygen vacancies, as important reactive sites in CeO 2 materials, can regulate its electronic structure, energy band structure and promote carrier separation, thereby improving its macroscopic electrical and chemical properties, enhancing redox ability and catalytic performance. In the present invention, Co 2+ doped CeO 2 , which helps to form the nano-sheet structure during the high-temperature pyrolysis process, and at the same time effectively promotes the regulation of the electronic structure and the formation of oxygen vacancies of the CeO 2 material, thereby greatly improving the mass / charge transfer efficiency and electrochemical performance of the CeO 2 material, and finally enabling the composite electrode to detect acetaminophen with high precision.

[0012] Preferably, the pretreatment of the GF in step (1) specifically includes the following steps:

[0013] In an air atmosphere, the GF is kept at 400 °C for 10 h, naturally cooled to room temperature, and then washed and dried to obtain the pretreated GF.

[0014] Beneficial effects: Graphite felt is a three-dimensional graphite carbon fiber felt made by high-temperature carbonization treatment. Due to its high volume porosity, high specific surface area, good electrical conductivity, good thermal stability and chemical stability, it is very suitable as a conductive substrate material and is widely used in the electrochemical field. In addition, the pretreated GF in the present invention will carry certain hydrophilic groups, thereby improving the hydrophilicity of the electrode surface and further improving the electrochemical activity.

[0015] Preferably, the washing is carried out using ultrapure water;

[0016] The drying conditions are: drying at 20 - 100 °C under a vacuum condition of 0.02 - 0.08 Mpa for 8 - 16 h.

[0017] Beneficial effects: Using ultrapure water for cleaning in the present invention can effectively protect the electrode from being contaminated by other impurities such as microorganisms; vacuum drying can effectively and quickly dry the pretreated GF and ensure to a certain extent that the electrode is not contaminated.

[0018] Preferably, the preparation of Co-Ce precursor / GF in step (2) specifically includes the following steps:

[0019] Under vigorous stirring conditions, cobalt acetate tetrahydrate, cerium nitrate hexahydrate and hexamethylenetetramine are dissolved in an organic solvent, and then the pretreated GF is added and soaked. Then, a solvothermal reaction is carried out at 170 °C for 8 h. After the reaction is completed, it is cooled and washed to obtain the Co-Ce precursor / GF.

[0020] Beneficial effects: By this solvothermal method, the present invention can successfully in-situ synthesize leaf-shaped Co-Ce precursors on the complete surface of GF carbon fibers, which is beneficial for further derivation.

[0021] Preferably, the addition ratio of cobalt acetate tetrahydrate, cerium nitrate hexahydrate, hexamethylenetetramine and the organic solvent is (0.25-1) mmol:(1-2) mmol:(0.8-0.98) mmol:(10-17) mL;

[0022] More preferably, the addition ratio of cobalt acetate tetrahydrate, cerium nitrate hexahydrate, hexamethylenetetramine and the organic solvent is (0.25-1) mmol:1.5 mmol:125 mg:13.5 mL;

[0023] The organic solvent is a mixed solvent obtained by mixing anhydrous ethanol and ethylene glycol in a volume ratio of (2-12):(3-10).

[0024] More preferably, the volume ratio of anhydrous ethanol to ethylene glycol is 7:6.5.

[0025] Beneficial effects: By selecting the above raw material ratio, Co can be effectively doped into the CeO 2+ lattice, which not only helps to form oxygen vacancies, but also helps the Co-Ce precursor to maintain a flaky structure during pyrolysis and further form nanosheets, increasing the specific surface area of the two-dimensional material and exposing more active sites, thereby improving the material / charge transfer efficiency in the electrochemical process and enhancing the catalytic performance. 2 Preferably, the stirring speed is 115-135 r / min, and the stirring time is 10-50 min;

[0026] The soaking temperature is room temperature, and the soaking time is 10-50 min;

[0027] In the washing process, the detergent is ethanol.

[0028]

[0029] ​Beneficial effects: Under the above conditions, by vigorously stirring for 30 min, the added reagent can be quickly and uniformly dissolved in the solvent; by soaking for 30 min, the reagent can be effectively adsorbed on the surface of GF, which is beneficial to the in-situ growth of Co-Ce precursor on the surface of GF; by washing with ethanol, the excess substances that have not grown on the surface of GF can be removed, and it is beneficial to the rapid drying of Co-Ce precursor / GF.

[0030] Preferably, in step (4), the Co-CeO 2 The preparation of the Co-CeO₂ NSs / GF composite electrode includes the following steps:

[0031] Under an air atmosphere, the Co-Ce precursor / GF is heated to 400 °C and held for 2 h and then cooled to obtain the Co-CeO₂ 2 NSs / GF composite electrode.

[0032] Preferably, the heating rate is 1-5 °C / min; the cooling is natural cooling to room temperature.

[0033] Beneficial effects: After high-temperature heat treatment under the above conditions, Co-CeO₂ 2 NSs / GF still well retains the flaky morphology of Co-Ce precursor / GF and forms two-dimensional Co-CeO₂ 2 nanosheets; a heating rate of 1 °C / min is a relatively slow heating rate, which can effectively prevent the collapse of the material morphology caused by too fast heating.

[0034] A composite electrode prepared by the preparation method of a composite electrode for detecting paracetamol.

[0035] Beneficial effects: The composite electrode prepared by the preparation method provided by the present invention is a composite electrode in which nanomaterials with uniform morphology are in-situ grown on the surface of graphite felt. This composite electrode can not only give full play to the respective advantages of several components, but also the synergistic effect between the components enhances the conductivity, stability and electrochemical response of the composite material.

[0036] An application of a composite electrode in an electrochemical sensor for detecting paracetamol.

[0037] Beneficial effects: The composite electrode in the present invention for detecting paracetamol by an electrochemical method has the advantages of low equipment cost, simple instrument operation, simple sample pretreatment, high detection efficiency, high sensitivity, low detection limit and good selectivity.

[0038] The present invention discloses a composite electrode for detecting paracetamol, its preparation method and application. The present invention improves the performance of CeO₂-based materials through a surface defect treatment method, prepares a composite electrode with GF as the electrode substrate material, and finally obtains Co-CeO₂ 2 ​2 The NSs / GF composite electrode can not only give full play to the respective advantages of each component, but also the synergistic effect of each component enhances the conductivity, stability and electrochemical response of the composite material. Through this method, nanomaterials with uniform morphology can be prepared. The Co-CeO 2 The detection of ACOP by the NSs / GF composite electrode can be carried out in a neutral medium at a low potential, and it exhibits advantages such as good detection sensitivity, cyclic stability, anti-interference ability and high recovery rate of actual samples. Moreover, after the composite electrode in the present invention is applied to an electrochemical sensor, it also has good recovery rate and small relative standard deviation for the electrochemical detection of ACOP in actual samples of commercially available ACOP tablets and human urine samples. It can be seen that the present invention can achieve efficient detection of ACOP and provides a new feasible idea for the electrochemical detection of ACOP. Brief Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 SEM scanning electron microscope images of Co-Ce precursor / GF, Co-CeO 2 NSs / GF obtained in Example 1 of the present invention and CeO 2 / GF obtained in Comparative Example 2;

[0041] Among them, A is Co-Ce precursor / GF obtained in Example 1, B is CeO 2 / GF obtained in Comparative Example 2, and C is the Co-CeO 2 NSs / GF composite electrode obtained in Example 1;

[0042] Figure 2 It is a bar chart of material optimization for the detection of ACOP in the present invention and the oxidation peak current and response current values of each electrode, and a CV curve of raw material ratio optimization;

[0043] Among them, A is the CV diagram of GF, the composite electrodes obtained in Example 1, Comparative Example 1 and 2 in 0.01 M PBS solution containing 0.5 mM ACOP, and B is the Figure 2 bar chart of the oxidation peak current and response current values of each electrode in part A of the above, and C is the CV diagram of the composite electrodes obtained in Examples 1-3 in 0.01 M PBS solution containing 0.5 mM ACOP;

[0044] Figure 3 It is Co-CeO obtained in Example 12 Chronocurrent curves of the NSs / GF composite electrode for the detection of different concentrations of ACOP;

[0045] Among them, A is the chronocurrent curve of ACOP in the concentration range of 0.25 μM to 437.22 μM at a working potential of 0.61 V, and B is the linear fitting curve of the current response of ACOP in the concentration range of 0.25 μM to 437.22 μM at a working potential of 0.61 V;

[0046] Figure 4 Co-CeO obtained in Example 1 of the present invention 2 Anti-interference ability, long-term detection stability and long-term stability test of the NSs / GF composite electrode for ACOP detection;

[0047] Among them, A is in Na + , K + , glucose (Glu), fructose (Fru), L-methionine (Met), L-proline (Pro), L-alanine (Ala) and L-serine (Ser) interference substances, Co-CeO 2 Chronocurrent curves of the NSs / GF composite electrode for ACOP detection, B is the chronocurrent curve of the NSs / GF composite electrode for ACOP detection for 3000 s, and C is the normalized bar chart of the current response of the Co-CeO 2 NSs / GF composite electrode for ACOP detection every three days within 15 days. 2 NSs / GF composite electrode for ACOP detection. Detailed implementation manners

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0049] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0050] The commercially available GF used in the embodiments of the present invention is the graphite felt produced by Gansu Haoshi Carbon Fiber Co., Ltd., with a thickness of 3 mm.

[0051] Example 1

[0052] A preparation method of a composite electrode for detecting paracetamol, comprising the following steps:

[0053] (1) Commercial GF pretreatment

[0054] The commercially available GF was cut into pieces with dimensions of 2 cm × 1 cm × 2 mm and placed in a porcelain boat. Under an air atmosphere, it was kept at 400 °C for 10 h, naturally cooled to room temperature, then the surface residues were washed with ultrapure water, and then vacuum dried at 60 °C and 0.05 MPa for 12 h to obtain the pretreated GF.

[0055] (2) Preparation of Co-Ce precursor / GF

[0056] First, 7 mL of anhydrous ethanol and 6.5 mL of ethylene glycol were mixed to obtain a mixed solvent. Then, 0.5 mmol of cobalt acetate tetrahydrate, 1.5 mmol of cerium nitrate hexahydrate, and 0.89 mmol of hexamethylenetetramine were dissolved in the mixed solvent under a stirring speed of 120 r / min and continuously stirred for 30 min to obtain a mixed solution. Subsequently, the pretreated GF obtained in step (1) was put into the mixed solution and soaked for 30 min, and then the system was transferred to a polytetrafluoroethylene-lined autoclave and subjected to a solvothermal reaction at 170 °C for 8 h. After natural cooling, the obtained product was rinsed several times with anhydrous ethanol and naturally dried to obtain Co-Ce precursor / GF.

[0057] (3) Preparation of Co-CeO 2 NSs / GF composite electrode

[0058] The Co-Ce precursor / GF obtained in step (2) was placed in a porcelain boat. Under an air atmosphere, it was heated at a heating rate of 1 °C / min and kept at 400 °C for 2 h, and then naturally cooled to room temperature to obtain Co-CeO 2 NSs / GF composite electrode.

[0059] Example 2

[0060] A preparation method of a composite electrode for detecting paracetamol, which is different from Example 1 in that:

[0061] In step (2), 0.25 mmol of cobalt acetate tetrahydrate was taken, and the remaining steps and parameters were the same as those in Example 1.

[0062] Example 3

[0063] A preparation method of a composite electrode for detecting paracetamol, which is different from Example 1 in that:

[0064] In step (2), 1 mmol of cobalt acetate tetrahydrate was taken, and the remaining steps and parameters were the same as those in Example 1.

[0065] Example 4

[0066] A preparation method of a composite electrode for detecting paracetamol, comprising the following steps:

[0067] (1) Pretreatment of commercially available GF

[0068] The commercially available GF was cut into pieces with dimensions of 2 cm × 1 cm × 2 mm and placed in a porcelain boat. Under an air atmosphere, it was kept at 400 °C for 10 h, naturally cooled to room temperature, then the surface residues were washed with ultrapure water, and then vacuum dried at 20 °C and 0.02 MPa for 8 h to obtain the pretreated GF;

[0069] (2) Preparation of Co-Ce precursor / GF

[0070] First, 2 mL of absolute ethanol and 3 mL of ethylene glycol were mixed to obtain a mixed solvent. Then, 0.25 mmol of cobalt acetate tetrahydrate, 1 mmol of cerium nitrate hexahydrate, and 0.8 mmol of hexamethylenetetramine were dissolved in the mixed solvent under a stirring speed of 115 r / min and continuously stirred for 10 min to obtain a mixed solution. Subsequently, the pretreated GF obtained in step (1) was put into the mixed solution and soaked for 10 min, and then the system was transferred to a high-pressure reaction kettle with a polytetrafluoroethylene lining and subjected to a solvothermal reaction at 170 °C for 8 h. After natural cooling, the obtained product was rinsed several times with absolute ethanol and naturally dried to obtain Co-Ce precursor / GF;

[0071] (3) Preparation of Co-CeO 2 NSs / GF composite electrode

[0072] The Co-Ce precursor / GF obtained in step (2) was placed in a porcelain boat. Under an air atmosphere, it was heated at a heating rate of 3 °C / min and kept at 400 °C for 2 h, and then naturally cooled to room temperature to obtain Co-CeO 2 NSs / GF composite electrode.

[0073] Example 5

[0074] A preparation method of a composite electrode for detecting paracetamol, comprising the following steps:

[0075] (1) Pretreatment of commercially available GF

[0076] The commercially available GF was cut into pieces with dimensions of 2 cm × 1 cm × 2 mm and placed in a porcelain boat. Under an air atmosphere, it was kept at 400 °C for 10 h, naturally cooled to room temperature, then the surface residues were washed with ultrapure water, and then vacuum dried at 100 °C and 0.08 MPa for 16 h to obtain the pretreated GF;

[0077] (2) Preparation of Co-Ce precursor / GF

[0078] First, 12 mL of absolute ethanol and 10 mL of ethylene glycol were mixed to obtain a mixed solvent. Then, 1 mmol of cobalt acetate tetrahydrate, 2 mmol of cerium nitrate hexahydrate, and 0.98 mmol of hexamethylenetetramine were dissolved in the mixed solvent under a stirring speed of 135 r / min and continuously stirred for 50 min to obtain a mixed solution. Subsequently, the pretreated GF obtained in step (1) was placed in the mixed solution and soaked for 50 min. Then, the system was transferred to a polytetrafluoroethylene-lined autoclave and subjected to a solvothermal reaction at 170 °C for 8 h. After natural cooling, the obtained product was rinsed several times with absolute ethanol and air-dried naturally to obtain Co-Ce precursor / GF;

[0079] (3) Preparation of Co-CeO 2 NSs / GF composite electrode

[0080] The Co-Ce precursor / GF obtained in step (2) was placed in a porcelain boat. Under an air atmosphere, it was heated at a heating rate of 5 °C / min and held at 400 °C for 2 h, and then naturally cooled to room temperature to obtain Co-CeO 2 NSs / GF composite electrode.

[0081] Comparative Example 1

[0082] A preparation method of a composite electrode, which is different from Example 1 in that:

[0083] In step (2), cerium nitrate hexahydrate was not added, and the remaining steps and parameters were the same as those in Example 1, and the product Co 3 O 4 / GF composite electrode was obtained.

[0084] Comparative Example 2

[0085] A preparation method of a composite electrode, which is different from Example 1 in that:

[0086] In step (2), cobalt acetate tetrahydrate was not added, and the remaining steps were the same as those in Example 1, and the product CeO 2 / GF composite electrode was obtained.

[0087] Technical effects:

[0088] (1) The scanning electron microscope images of the Co-Ce precursor / GF obtained in step (2) of Example 1, the Co-CeO 2 NSs / GF composite electrode obtained in step (3), and the CeO 2 / GF composite electrode obtained in Comparative Example 2 are as shown in Figure 1 Figure. Among them, part A is Co-Ce precursor / GF, part B is CeO 2 / GF composite electrode, and part C is Co-CeO 2 NSs / GF composite electrode, as shown inFigure 1 As shown in part A and its inset in Figure, leaf-like Co-Ce precursors were successfully synthesized in-situ on the entire surface of GF carbon fibers by a solvothermal method; from Figure 1 As can be seen from part B and its inset in Figure, CeO 2 / GF only generally retained the flaky structure of the precursor after high-temperature heat treatment via Ce precursor / GF, and formed thick flakes with rough surfaces composed of stacked CeO 2 nanoparticles; while Figure 1 As can be observed from part C and its inset in Figure, the Co-CeO 2 / GF composite electrode still retained the flaky morphology of the precursor well and formed two-dimensional Co-CeO 2 nanosheets after high-temperature heat treatment via Co-Ce precursor / GF composite electrode.

[0089] (2) Electrochemical performance test

[0090] The electrodes GF, the Co 3 O 4 / GF composite electrode obtained in Comparative Example 1, the CeO 2 / GF composite electrode obtained in Comparative Example 2, and the Co-CeO 2 NSs / GF composite electrode obtained in Example 1 were respectively applied to an electrochemical sensor for detecting paracetamol, and the cyclic voltammetry (CV) method was used to test the electrochemical performance of the above several electrodes. The results showed that the Co-CeO 2 NSs / GF composite electrode had a stronger current response signal, better electrochemical reversibility and cyclic stability. Among them, an electrochemical workstation (Chenhua CHI660e) was used as the experimental instrument, a 0.01 M PBS solution was used as the supporting electrolyte solution, the prepared composite electrode was used as the working electrode, a saturated calomel electrode (SCE) was used as the reference electrode, and a platinum wire electrode was used as the counter electrode to form a three-electrode system. Cyclic voltammetry parameters: potential window: -1 V to 1 V; scanning speed: 5 mV / s. Finally, the results shown in Figure 2 Figure were obtained:

[0091] As Figure 2 shown in part A of Figure, two pairs of redox peaks appeared in the CV curve of the Co-CeO 2 composite electrode, and the main strong redox peaks were at about 0.6 V and 0.07 V; in contrast, one pair of similar redox peaks also appeared in the CV curves of GF, CeO 2 / GF composite electrode and Co 3 O 4 / GF composite electrode, and they showed an electrochemical response to ACOP, but the CV curves of GF and CeO 2The peak current and response current of the Co-CeO / GF composite electrode are significantly smaller than those of the Co-CeO 2 composite electrode; while the peak current of the Co 3 O 4 / GF composite electrode is slightly larger than that of the Co-CeO 2 composite electrode, but the redox peak is weak and basically shows capacitive current. Based on the above analysis and Figure 2 the results in part B, the order of the response current of each electrode to ACOP is Co-CeO 2 / GF composite electrode > CeO 2 / GF composite electrode > Co 3 O 4 / GF composite electrode > GF, which indicates that the CeO 2 material can catalyze the oxidation of ACOP to a certain extent, and Co 2+ doping can further improve the electrochemical detection performance of the composite electrode for ACOP.

[0092] To optimize the preparation conditions of the composite electrode, cyclic voltammetry (CV) was used to test the electrochemical performance. The results show that when 0.5 mmol of cobalt acetate tetrahydrate was taken, the prepared composite electrode had better electrochemical performance. As Figure 2 shown in part C, when the molar ratio of Co:Ce in the Co-Ce precursor / GF was 0.5:1.5, the CV curve of the prepared Co-CeO 2 / GF composite electrode showed the largest current response.

[0093] Chronoamperometry (CA) was used to study the linear range, sensitivity and lowest detection limit of the Co-CeO 2 NSs / GF composite electrode for detecting ACOP. The optimized results were a linear range of 0.25 μM to 118.40 μM and 118.40 μM to 437.22 μM, a sensitivity of 4.86 A / M and 0.21 A / M, and a lowest detection limit of 9.18 nM.

[0094] In summary, the electrochemical sensor provided by the present invention has a linear response range to ACOP of 0.25 μM to 118.40 μM and 118.40 μM to 437.22 μM, a sensitivity of 4.86 A / M and 0.21 A / M, and a lowest detection limit of 9.18 nM (S / N = 3).

[0095] (3) As Figure 3 shown in part A, by continuously dropping several concentrations of ACOP into a 0.01 M PBS solution to obtain a CA curve, it can be clearly observed that the response current increases with the increase of the ACOP concentration. Subsequently, we performed piecewise linear fitting based on the current value and the added concentration of ACOP. As Figure 3As shown in part B, Co-CeO 2 / GF composite electrode was used to detect ACOP, and linear fitting equations were obtained in the concentration ranges of 0.25 μM to 118.40 μM and 118.40 μM to 437.22 μM respectively: y (μM) = 4.86x (μM) + 3.33 (R 2 = 0.996); y (μM) = 0.21x (μM) + 554.15 (R 2 = 0.996); Therefore, the linear range of this ACOP electrochemical sensor is 0.25 μM to 118.40 μM and 118.40 μM to 437.22 μM; the sensitivities are 4.86 A / M and 0.21 A / M respectively; the detection limit is 9.18 nM (S / N = 3).

[0096] (4) As shown in part A Figure 4 , by adding inorganic ion interferents and organic molecule interferents 100 times the concentration of ACOP, such as Na + , K + , glucose (Glu), fructose (Fru), L-methionine (Met), L-proline (Pro), L-alanine (Ala) and L-serine (Ser), there was no obvious current response, indicating that the Co-CeO 2 / GF composite electrode has good anti-interference ability for ACOP. As shown in the CA curve in part B Figure 4 , the current remained at about 85% of the original after 3000 s, indicating that the composite electrode has good long-term detection stability. As shown in part C Figure 4 , for the long-term stability test of the Co-CeO 2 / GF composite electrode to detect ACOP, after testing the response current of the composite electrode to ACOP at the same concentration every three days and normalizing the results, the results showed that after 15 days, the current retention rate of the Co-CeO 2 / GF composite electrode to detect ACOP could reach 91%, indicating that the composite electrode has good long-term stability.

[0097] Application example:

[0098] Application of a composite electrode for detecting paracetamol in detecting paracetamol in urine:

[0099] The Co-CeO 2 / GF composite electrode in Example 1 was used to determine the ACOP content in tablets and urine. Among them, the tablets were paracetamol tablets purchased from a pharmacy, and the main ingredient was paracetamol. The specific method is as follows:

[0100] Using 0.01 M PBS solution as the supporting electrolyte, a commercially available ACOP tablet was formulated into a ACOP drug solution with a certain concentration; in addition, using 0.01 M PBS solution as the supporting electrolyte solution, a human urine sample containing a certain concentration of ACOP (diluted 50 times) was prepared by the standard addition method. Then, the CA test was carried out using the above-prepared ACOP drug solution and urine dilution as the electrolyte solutions.

[0101] The results are shown in Table 1:

[0102] Table 1

[0103]

[0104]

[0105] It can be seen from Table 1 that: for the Co-CeO 2 / GF composite electrode provided by the present invention when detecting the ACOP content in tablets and urine, when there are 50 μM, 100 μM, and 150 μM of acetaminophen, the Co-CeO 2 / GF composite electrode is basically accurate in detecting the ACOP content. The recovery rate range of ACOP in commercially available tablets is from 98.3% to 103.76%, and the relative standard deviation is between 1.25% and 2.76%; the recovery rate range of ACOP in human urine is from 97.64% to 102.64%, and the RSD is between 1.37% and 2.52%, indicating that the ACOP electrochemical sensor constructed by the Co-CeO 2 / GF composite electrode has excellent practicability.

[0106] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. Preparation method of a composite electrode for detecting paracetamol, characterized in that, it includes the following steps: (1) Pretreat GF to obtain pretreated GF; (2) Immerse the pretreated GF into a cobalt-cerium precursor solution to prepare Co-Ce precursor / GF; The preparation of the Co-Ce precursor / GF specifically includes the following steps: Under vigorous stirring conditions, dissolve cobalt acetate tetrahydrate, cerium nitrate hexahydrate and hexamethylenetetramine in an organic solvent, then add the pretreated GF and soak it, and then carry out a solvothermal reaction at 170 °C for 8 h. After the reaction is completed, cool and wash to obtain the Co-Ce precursor / GF; The addition ratio of cobalt acetate tetrahydrate, cerium nitrate hexahydrate, hexamethylenetetramine and the organic solvent is (0.25-1) mmol:(1-2) mmol:(0.8-0.98) mmol:(10-17) mL; The organic solvent is a mixed solvent obtained by mixing anhydrous ethanol and ethylene glycol in a volume ratio of (2-12):(3-10); (3) Heat-treat the Co-Ce precursor / GF to prepare the Co-CeO 2 NSs / GF composite electrode.

2. The preparation method of a composite electrode for detecting paracetamol according to claim 1, characterized in that, The pretreatment of the GF in step (1) specifically includes the following steps: Under an air atmosphere, keep GF at 400 °C for 10 h, naturally cool to room temperature, and then wash and dry to obtain pretreated GF.

3. The preparation method of a composite electrode for detecting paracetamol according to claim 2, characterized in that, The washing is carried out using ultrapure water; The drying conditions are: drying at 20-100 °C and 0.02-0.08 Mpa vacuum for 8-16 h.

4. The preparation method of a composite electrode for detecting paracetamol according to claim 1, characterized in that, The stirring speed is 115-135 r / min, and the stirring time is 10-50 min; The soaking temperature is room temperature, and the soaking time is 10-50 min; The detergent in the washing process is ethanol.

5. The preparation method of a composite electrode for detecting paracetamol according to claim 1, characterized in that, The Co-CeO 2 preparation of the NSs / GF composite electrode includes the following steps: Under an air atmosphere, the Co-Ce precursor / GF was heated to 400 °C, held for 2 h, and then cooled to obtain the Co-CeO 2 NSs / GF composite electrode.

6. The preparation method of a composite electrode for detecting paracetamol according to claim 5, characterized in that, The heating rate is 1-5 °C / min; the cooling is natural cooling to room temperature.

7. A composite electrode prepared by the preparation method of a composite electrode for detecting paracetamol according to any one of claims 1-6.

8. Application of the composite electrode according to claim 7 in an electrochemical sensor for detecting paracetamol.

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