Solid-phase microextraction probe based on COF (copolymerized microsphere / MXene coating as well as preparation method and application of solid-phase microextraction probe

Abstract

The invention belongs to the technical field of food detection, and particularly relates to a solid-phase microextraction probe based on a COF (co) copolymer microsphere / MXene coating as well as a preparation method and application of the solid-phase microextraction probe. The preparation method comprises the following steps: carrying out amination treatment on a support carrier to obtain an aminated support carrier; the preparation method comprises the following steps: preparing an aminated support carrier, then loading a reaction monomer and a polymer skeleton on the surface of the aminated support carrier, then adding 2, 6-dialdehyde-1, 5-dihydroxynaphthalene (DHNDA), MXene and glacial acetic acid for in-situ assembly to obtain the solid-phase microextraction probe, and improving the extraction efficiency of the probe on an organophosphorus pesticide through a COF (copolymerized microsphere / MXene coating. The high-selectivity and high-sensitivity detection on the organophosphorus pesticide in the tea leaf sample is realized.

Description

Technical Field

[0001] This invention belongs to the field of food testing technology, and more specifically relates to a solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating, its preparation method and application. Background Technology

[0002] Long-term consumption of tea containing organophosphate pesticides (OPPs) may cause various respiratory, cardiovascular, and autoimmune diseases in humans, leading to widespread concern about OPP residues in tea. Hot water brewing is a traditional way of drinking tea. During brewing, OPPs in the tea leaves leach into the tea infusion, even with a high octanol-water partition coefficient (logarithm). Kow Nonpolar OPPs, characterized by their low solubility in water, have significant toxicity and pose a threat to human health.

[0003] The analysis of OPP residues typically relies on chromatographic techniques, and sample pretreatment plays a crucial role in chromatographic analysis. Among numerous pretreatment techniques, immersion solid-phase microextraction (DI-SPME) technology has advantages such as low consumption of adsorbent material and sample, high enrichment factor, simple operation, low consumption of organic solvents, and no need for complex equipment, making it an important technique for OPP residue detection. This technique directly immerses the adsorbent coating in the sample solution, increasing the contact surface between the adsorbent coating and the analyte. This characteristic not only improves the extraction efficiency of the analyte but also shortens the extraction time. However, current SPME coating preparation methods mainly involve the material and support (SSWs) bonded through physical adhesion or electrochemical polymerization. Due to the lack of stable chemical bonds between the material and SSWs, coating peeling is prone to occur, thus affecting the extraction efficiency. Therefore, there is an urgent need to research and develop more robust coating preparation methods to improve the reliability and reproducibility of SPME probes in OPP detection. Summary of the Invention

[0004] The purpose of this invention is to provide a solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating, its preparation method and application, and more specifically, to provide a pretreatment method for a solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating for detecting organophosphorus pesticide residues in tea, so as to solve the problems existing in the prior art and achieve rapid and specific detection of OPPs pollution in tea.

[0005] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is to provide a method for preparing a solid-phase microextraction probe based on a COF@copolymer microsphere / MXene coating, the steps of which include: The support (SSWs) was aminated to obtain an aminated support (SSW-NH2). The aminated support was immersed in a solution containing the reactive monomer and polymer backbone. The reactive monomer and polymer backbone were then loaded onto the surface of the aminated support. Subsequently, 2,6-dialdehyde-1,5-dihydroxynaphthalene (DHNDA), MXene, and glacial acetic acid were added to perform an in-situ assembly reaction, yielding the solid-phase microextraction probe (COF). TAPB-DHNDA @DVB-NVP / MXene solid-phase coating probe); The reaction monomer is 1,3,5-tris(4-aminophenyl)benzene (TAPB). The polymer backbone is DVB-NVP.

[0006] Furthermore, the amination treatment step includes: immersing the support in a mixed solution of 3-aminopropyltriethoxysilane (APTES), ethanol, and water, and reacting to obtain the amination support.

[0007] Optionally, the volume ratio of 3-aminopropyltriethoxysilane (APTES), ethanol, and water in the mixed solution is 3-4:3-4:1-2.

[0008] Optionally, the reaction time is 1-2 h.

[0009] Furthermore, in the solution containing the reactive monomer and the polymer backbone, the concentration of the reactive monomer is 0.05-0.1 mmol / L, the concentration of the polymer backbone is 6-8 μg / mL, and the solvent is 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 1-2:4-8.

[0010] Furthermore, the step of loading the reactive monomer and polymer backbone is as follows: after ultrasonic and vibration treatment, preheating at 50-70 °C for 20-30 min.

[0011] Furthermore, in the in-situ assembly reaction step, the amount of 2,6-dialdehyde-1,5-dihydroxynaphthalene added is 0.05-0.1 mmol / L, the amount of MXene added is 0.5-1.0 mg / mL, and the amount of glacial acetic acid added is 1-2 mmol / L.

[0012] Furthermore, the MXene is Ti3C2T. x MXene.

[0013] Furthermore, the in-situ assembly reaction is carried out at a temperature of 60-80 °C for 5-6 h. Furthermore, the preparation steps of the DVB-NVP include: dissolving divinylbenzene (DVB) and vinylpyrrolidone (N-NVP) monomers in acetonitrile, and performing ultrasonic treatment under a nitrogen atmosphere to obtain DVB-NVP.

[0014] Optionally, the volume ratio of the divinylbenzene (DVB), vinylpyrrolidone (N-NVP), and acetonitrile is 4-6:4-5:10-20.

[0015] Optionally, the ultrasonic treatment time is 10-30 min.

[0016] The second technical solution of the present invention provides a solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating, wherein the solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating is prepared by the above preparation method.

[0017] The third technical solution of the present invention provides an application of the above-mentioned solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating in the detection of residual organophosphorus pesticides.

[0018] The fourth technical solution of this invention provides a method for detecting OPPs, comprising the following steps: S1. Sample pretreatment: Accurately weigh 5-10 g of the sample to be tested, add ultrapure water, seal and soak for 1-3 h to obtain the sample solution to be tested. S2. Establishment of standard curve: Solid-phase microextraction probes were used to perform solid-phase microextraction on a series of organophosphorus pesticide standard solutions of known concentrations, followed by analysis by gas chromatography-flame photometry detector; linear fitting was performed with pesticide concentration as the abscissa and chromatographic peak area as the ordinate to establish a quantitative prediction model. S3. Sample detection: Immerse the solid-phase microextraction probe into the sample solution obtained in step S1, and extract at 25-30 ℃ for 20-40 min. During extraction, magnetic stirring is used to assist the extraction. After extraction, transfer the probe to the gas chromatograph injection port for thermal desorption and chromatographic analysis to obtain the chromatographic peak area of ​​the target analyte. S4. Concentration Calculation: Substitute the peak area measured in step S3 into the quantitative prediction model established in step S2 to calculate the specific concentration of organophosphorus pesticides in the sample to be tested.

[0019] The present invention discloses the following technical effects: The in-situ grown COF@copolymer microspheres / MXene probes did not use any binders, effectively preserving the porous structure of COFs and providing the material with a large specific surface area and good permeability.

[0020] The solid-phase microextraction probe provided by this invention has excellent extraction performance, enabling efficient extraction of OPPs and subsequent quantitative detection of OPPs. Furthermore, the probe is easy to manufacture and its fabrication method is readily achievable, thus giving it promising practical applications. The extraction efficiency of the probe for organophosphorus pesticides is enhanced by a COF@copolymer microsphere / MXene coating, achieving sensitive detection of organophosphorus pesticides in tea samples. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the preparation process of the solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating according to the present invention.

[0022] Figure 2 This is a schematic diagram of the probe-based GC-FPD detection process for OPPs in tea.

[0023] Figure 3 Typical chromatograms for standard blank solutions and real samples with spiked OPPs. Detailed Implementation

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0027] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0028] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0029] Unless otherwise specified, all raw materials and reagents involved in the specific embodiments of this invention are commercially available products. Specifically, the tea used in the specific embodiments of this invention was purchased from a local wholesale market in Jimei District, Xiamen; the Ti3C2T used in the specific embodiments of this invention... x MXene is a commercially available product with a few-layer structure and a nanometer-scale size.

[0030] Unless otherwise specified, room temperature and normal temperature in the specific embodiments of this invention refer to 20-30℃.

[0031] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0032] The support carrier used in the specific embodiment of the present invention is obtained by cutting SSWs (ultrafine stainless steel microwires) into pieces of about 10-15 cm, immersing one end in aqua regia for about 15-20 min, then thoroughly rinsing with acetone, ethanol and ultrapure water, and drying them in an oven at a certain temperature (about 50-70°C) and for a certain time (about 10-30 min) to obtain bare SSWs with a rough surface.

[0033] In some specific embodiments, the present invention provides a method for preparing a solid-phase microextraction probe based on a COF@copolymer microsphere / MXene coating, the steps of which include: S1. Cut SSWs into 12cm lengths, immerse one end in aqua regia for 15min, then rinse thoroughly with acetone, ethanol and ultrapure water, and dry in an oven (70℃, 10min) to obtain bare SSWs with rough surfaces. Immerse the bare SSWs in a mixed solution of 3-aminopropyltriethoxysilane (APTES), ethanol and water (volume ratio 3:4:1) and react for 2h to obtain SSW-NH2. S2. Divinylbenzene (DVB) and vinylpyrrolidone (N-NVP) monomers are dissolved in acetonitrile and ultrasonically treated under a nitrogen atmosphere for 20-30 min to obtain DVB-NVP; The volume ratio of divinylbenzene (DVB), vinylpyrrolidone (N-NVP), and acetonitrile is 4-6:4-5:10-20. S3. SSW-NH2 was immersed in a solution containing TAPB and DVB-NVP, and after ultrasonic and vibration treatment, it was preheated at 50-70 ℃ for 20-30 min. TAPB and DVB-NVP were then loaded onto the surface of SSW-NH2, followed by the addition of DHNDA, MXene, and glacial acetic acid. The mixture was then magnetically stirred at 60-80 ℃ for 5-6 h to carry out the in-situ assembly reaction, yielding a solid-phase microextraction probe (COF). TAPB-DHNDA @DVB-NVP / MXene solid-phase coating probe) In the solution containing TAPB and DVB-NVP, the concentration of TAPB is 0.05-0.1 mmol / L, the concentration of DVB-NVP is 6-8 μg / mL, and the solvent is 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 1-2:4-8; the amount of DHNDA added is 0.05-0.1 mmol / L, the amount of MXene added is 0.5-1.0 mg / mL, and the amount of glacial acetic acid added is 1-2 mmol / L.

[0034] Figure 1 This is a schematic diagram of the preparation process of the solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating according to the present invention.

[0035] This invention enables the material to carry amino groups through amination treatment, followed by material connection and loading; loading and in-situ assembly are achieved through amide reactions between amino and carboxyl groups; no binders are used in the in-situ assembly, and the porous structure of COFs is effectively preserved; the raw materials not only provide the material with a large specific surface area and good permeability, but also significantly improve its performance in the extraction process, giving it excellent extraction performance.

[0036] Example 1 The preparation steps of the solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating include: S1. Immerse SSWs in a mixed solution of 3-aminopropyltriethoxysilane (APTES), ethanol and water in a volume ratio of 3:4:1 and react for 2 h to obtain SSW-NH2. S2. Divinylbenzene (DVB) and vinylpyrrolidone (N-NVP) monomers were dissolved in acetonitrile and ultrasonically treated for 15 min under a nitrogen atmosphere to obtain DVB-NVP. The volume ratio of divinylbenzene (DVB), vinylpyrrolidone (N-NVP), and acetonitrile is 6:4:15. S3. Immerse SSW-NH2 in a solution containing TAPB and DVB-NVP, perform ultrasonic and vibration treatment, preheat at 70℃ for 20 min, load TAPB and DVB-NVP onto the surface of SSW-NH2, and then add DHNDA and Ti3C2T. x MXene and glacial acetic acid were subjected to in-situ assembly reaction under magnetic stirring at 80 °C for 5 h to obtain a solid-phase microextraction probe (COF). TAPB-DHNDA @DVB-NVP / MXene solid-phase coating probe) In the solution containing TAPB and DVB-NVP, the concentration of TAPB was 0.05 mmol / L, the concentration of DVB-NVP was 6 μg / mL, and the solvent was 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 1:4. The amount of DHNDA added was 0.05 mmol / L, the amount of MXene added was 0.5 mg / mL, and the amount of glacial acetic acid added was 2 mmol / L.

[0037] Test case Accurately weigh 5 g of homogenized tea sample, crush it, and soak it in ultrapure water for 2 h (room temperature). Seal the sample with a septum cap for SPME analysis. Install the solid-phase microextraction probe (Example 1) and a commercial probe (model 01-06, Qingdao Zhenzheng Analytical Instruments Co., Ltd.) onto the SPME holder for manual sampling. Mount the probe onto the SPME sampling stage, extend it from the needle, and immerse it in the sample solution at 25 °C for 20 min. During extraction, stir the solution at a constant speed using a magnetic stirrer. Immediately after extraction, transfer the probe to a GC-FPD injector for chromatographic analysis.

[0038] Figure 2 This is a schematic diagram of the probe-based GC-FPD detection process for OPPs in tea.

[0039] Detection of OPP concentration in tea: S1. Prepare standard solutions of phorate and phosmet with a concentration range of 0.250-250 μg / L and standard solution of phosmet with a concentration range of 0.150-250 μg / L respectively. Take the above three standard solutions and use the DI-SPME-GC-FPD program system constructed in the above steps to detect OPPs at different concentrations. GC-FPD program: An Agilent HP-5 column (250 mm × 4.6 mm, 5 μm) with a phosphorus filter was used; high-purity N2 was used as the carrier gas at a flow rate of 1.5 mL / min; the injector and detector temperatures were 270 °C; injection was performed in splitless mode; the oven temperature program was as follows: initial column temperature of 50 °C for 3 min, then increased to 130 °C at 10 °C / min for 3 min, followed by an increase to 200 °C at 12 °C / min, and finally increased to 270 °C at 20 °C / min; this method uses retention time to determine OPPs and uses peak area to quantify and calculate extraction recoveries; the SPME apparatus was assembled in-house, and chromatographic data were processed using an Agilent DA Express.

[0040] Table 1 shows the method validation parameters for each pesticide using the DI-SPME-GC-FPD method; Table 1 S2. Solid-phase microextraction probe (COF) prepared using the example. TAPB-DHNDA The OPPs in tea samples were determined using a DVB-NVP / MXene solid-phase coated probe. No phorate, bromoxynil, or isopyram were detected in the tea samples. To evaluate the accuracy of the method, five replicate analyses were performed on tea samples spiked with 10.0 μg / L and 50.0 μg / L of OPPs to determine the method recovery. The method recovery was determined by expressing the measured average concentration as a percentage of the analyte spike concentration, and the results are shown in Table 2.

[0041] Table 2. Recovery rates of phorate, phosmet, and indomethacin in tea by solid-phase microextraction probes. Figure 3 Typical chromatograms for standard blank solutions and real samples with spiked OPPs.

[0042] From Table 2 and Figure 3 It can be seen that for tea samples with RSDs between 2.33% and 5.88%, the recoveries of the three OPP methods ranged from 82.5% to 92.3%. Therefore, it can be concluded that the constructed COF... TAPB-DHNDA The @DVB-NVP / MXene probe provides excellent trace enrichment properties for OPPs, and the established method exhibits high accuracy and versatility.

[0043] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating, characterized in that the steps include... include: The support carrier is subjected to amination treatment to obtain an amination support carrier; The aminated support was immersed in a solution containing reactive monomers and a polymer backbone. The reactive monomers and polymer backbone were loaded onto the surface of the aminated support. Then, 2,6-dialdehyde-1,5-dihydroxynaphthalene, MXene and glacial acetic acid were added to carry out an in-situ assembly reaction to obtain the solid-phase microextraction probe. The reaction monomer is 1,3,5-tris(4-aminophenyl)benzene; The polymer backbone is DVB-NVP.

2. The preparation method according to claim 1, characterized in that, The amination process includes immersing the support in a mixed solution of 3-aminopropyltriethoxysilane, ethanol, and water, and reacting to obtain the amination support.

3. The preparation method according to claim 2, characterized in that, The volume ratio of 3-aminopropyltriethoxysilane, ethanol and water in the mixed solution is 3-4:3-4:1-2; And / or, the reaction time is 1-2 h.

4. The preparation method according to claim 1, characterized in that, The solution containing the reactive monomer and the polymer backbone has a reactive monomer concentration of 0.05-0.1 mmol / L, a polymer backbone concentration of 6-8 μg / mL, and a solvent of 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 1-2:4-8.

5. The preparation method according to claim 1, characterized in that, The step of loading the reactive monomer and polymer backbone is as follows: after ultrasonic and vibration treatment, preheating at 50-70 ℃ for 20-30 min.

6. The preparation method according to claim 1, characterized in that, In the in-situ assembly reaction step, the amount of 2,6-dialdehyde-1,5-dihydroxynaphthalene added is 0.05-0.1 mmol / L, the amount of MXene added is 0.5-1.0 mg / mL, and the amount of glacial acetic acid added is 1-2 mmol / L. And / or, the in-situ assembly reaction is carried out at a temperature of 60-80 °C for a time of 5-6 h; And / or, the MXene is Ti3C2T x MXene.

7. The preparation method according to claim 1, characterized in that, The preparation steps of the DVB-NVP include: dissolving divinylbenzene and vinylpyrrolidone monomers in acetonitrile, and performing ultrasonic treatment under a nitrogen atmosphere to obtain DVB-NVP; the volume ratio of divinylbenzene, vinylpyrrolidone and acetonitrile is 4-6:4-5:10-20; the ultrasonic treatment time is 10-30 min.

8. A solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating, characterized in that, The solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating is prepared by the preparation method described in any one of claims 1-7.

9. The application of the solid-phase microextraction probe based on COF@copolymer microspheres / MXene coating as described in claim 8 in the detection of residual organophosphorus pesticides.

10. A method for detecting OPPs, characterized in that the steps include... include: S1. Sample pretreatment: Accurately weigh 5-10 g of the sample to be tested, add ultrapure water, seal and soak for 1-3 h to obtain the sample solution to be tested. S2. Establishment of standard curve: Solid-phase microextraction probe as described in claim 8 was used to perform solid-phase microextraction on a series of organophosphorus pesticide standard solutions of known concentrations, followed by analysis by gas chromatography-flame photometry detector; linear fitting was performed with pesticide concentration as the abscissa and chromatographic peak area as the ordinate to establish a quantitative prediction model. S3. Sample detection: Immerse the solid phase microextraction probe into the sample solution obtained in step S1, and extract at 25-30 ℃ for 20-40 min. During extraction, magnetic stirring is used to assist the extraction process. After extraction, the probe is transferred to the gas chromatograph injection port for thermal desorption and chromatographic analysis to obtain the chromatographic peak area of ​​the target analyte. S4. Concentration Calculation: Substitute the peak area measured in step S3 into the quantitative prediction model established in step S2 to calculate the specific concentration of organophosphorus pesticides in the sample to be tested.

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