Preparation method and application of a solid phase microextraction device with a coating of a derivatized porous carbon material

Abstract

This invention discloses a method for preparing a solid-phase microextraction (SPME) device coated with a porous carbon material (DPCM) derived from a covalent organic framework (COF). The method primarily includes the following steps: preparing DPCM; preparing a DPCM sol-gel solution; inserting treated fibers into the DPCM sol-gel solution, extracting and curing them, and repeating this process multiple times to produce a DPCM-coated fiber. This fiber is then secured in a 1 mL microsyringe to form a solid-phase microextraction device. Combined with gas chromatography, the device is used for the extraction and analysis of trace phthalates (PAEs) in water samples, significantly improving detection sensitivity.

Description

Technical Field

[0001] The invention belongs to the technical field of sample pretreatment, and particularly relates to a preparation method of an SPME device using DPCM as a coating and an application thereof. Background Art

[0002] Phthalates (PAEs) are a class of plasticizers widely used in plastics and rubber to enhance their flexibility, plasticity, and elasticity. Because PAEs are not chemically bound to the polymer matrix, they are readily released from the material into the environment, potentially causing adverse health effects such as reproductive toxicity, embryotoxicity, and teratogenicity. Therefore, the development of rapid and sensitive methods for the quantitative detection of PAEs in the environment is crucial.

[0003] Due to the limitations of sample matrix and instrument sensitivity, appropriate sample pretreatment methods are essential for the detection of trace PAEs. Among traditional sample pretreatment techniques, liquid-liquid extraction is more commonly used, but its operation process is complicated, the consumption of organic solvents is large, and it is easy to cause secondary environmental pollution. SPME technology is a new sample pretreatment technology developed in the 1990s. The operation process does not require the use of organic solvents and is less affected by the matrix. It integrates sampling, concentration, and injection, overcoming the shortcomings of traditional sample pretreatment technologies. It is a green sample pretreatment method and is widely used in the extraction analysis of trace pollutants. The coating is a key factor in determining the extraction efficiency of SPME, so the development of new coatings remains a research hotspot in recent years.

[0004] COFs, with their large surface area, porous structure, and rich functional groups, have been developed as highly effective coating materials for SPME. DPCM, obtained by pyrolysis of COFs as precursors, exhibits a highly porous structure, high surface area, and excellent chemical stability, making it a promising coating material for SPME. However, research in this area is limited. Summary of the Invention

[0005] The present invention aims to provide a preparation method and application of an SPME device using DPCM as a coating.

[0006] The first object of the present invention is to provide a method for preparing an SPME device with a DPCM coating, the technical solution adopted is as follows:

[0007] S1. Weigh 100 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 130 mg of 4-formylphenylboronic acid, dissolve them in 10 mL of a 1:1 dioxane / mesitylene solution, mix thoroughly by ultrasonication, transfer the resulting solution to a reactor, and then place it in a 120°C oven for 72 hours. After cooling to room temperature, centrifugation, washing, and drying, a COF material is obtained. Finally, the COF material is placed in a tube furnace and calcined at 500-800°C for 2 hours under a nitrogen atmosphere. After cooling to room temperature, washing, centrifugation, and drying, the DPCM is obtained.

[0008] S2. 100 μL of dichloromethane, 100 μL of methyltrimethoxysilane, 100 μL of polydimethylsiloxane, and 30 mg of DPCM were added to a centrifuge tube and vortexed to mix thoroughly. Subsequently, 80 μL of trifluoroacetic acid (95% aqueous solution) was added as a catalyst and vortexed again to obtain a DPCM sol-gel solution. A stainless steel wire (0.3 mm diameter) was immersed at one end in a hydrofluoric acid solution. The surface acid impurities were washed with ultrapure water and allowed to dry at room temperature. The wire was then vertically immersed in the prepared sol-gel solution and rotated 20 times. The fiber was then removed and dried at room temperature for 2 min. This process was repeated six times to obtain a DPCM-coated fiber. Finally, the coated fiber was dried at room temperature for 24 h and then placed in a 280°C oven for 2 h. Before use, the fiber was assembled into a 1 mL microsyringe and activated at the gas chromatography inlet at 280°C for 2 h under nitrogen. This resulted in a solid-phase microextraction device.

[0009] The second object of the present invention is to apply the prepared SPME device to the extraction of PAEs in water samples, characterized in that the technical solution is as follows:

[0010] 20 mL of PAEs sample solution was transferred into a headspace bottle, placed in a 90°C magnetic stirring water bath, and the SPME device was inserted into the headspace bottle. Headspace extraction was performed for 25 min. The SPME device was removed and inserted into the gas phase inlet. Thermal desorption was performed at 290°C under nitrogen assistance to achieve extraction analysis of PAEs in the water sample.

[0011] The beneficial effects of the present invention compared to the prior art are:

[0012] After pyrolysis of the COF material, the resulting DPCM has a rougher surface, a larger specific surface area, and more active sites. Compared with the SPME device coated with COF, the SPME device coated with DPCM prepared in the present invention has better extraction performance and efficiency, and can improve the analytical sensitivity of PAEs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The infrared spectra (FT-IR) of monomers TAPT, FPBA and COF are shown.

[0014] Figure 2 (a) is the scanning electron microscope (SEM) image of COF, (b) is the SEM image of DPCM, and (c) is the SEM image of DPCM-coated fiber.

[0015] Figure 3 Chromatograms of PAEs extracted using SPME devices coated with DPCM prepared at different pyrolysis temperatures.

[0016] Figure 4 The chromatograms are before and after 100 μg / L PAEs extraction.

[0017] Figure 5 Chromatograms of PAEs extracted by SPME devices coated with COF and DPCM. Implementation Method

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Example 1

[0019] This embodiment provides a method for preparing an SPME device with a DPCM coating, comprising the following steps:

[0020] 100 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and 130 mg of 4-formylphenylboronic acid (FPBA) were weighed and dissolved in 10 mL of a 1:1 dioxane and mesitylene solution. The mixture was ultrasonically mixed and the resulting solution was transferred to a reactor. The reaction was then carried out in an oven at 120°C for 72 h. The reaction was then cooled to room temperature, centrifuged, washed, and dried to obtain a COF material. Finally, the COF material was placed in a tube furnace and calcined at 700°C for 2 h under a nitrogen atmosphere. After cooling to room temperature, the mixture was washed, centrifuged, and dried to obtain the DPCM.

[0021] To a centrifuge tube, 100 μL of dichloromethane, 100 μL of methyltrimethoxysilane, 100 μL of polydimethylsiloxane, and 30 mg of DPCM were added and vortexed to mix thoroughly. Subsequently, 80 μL of trifluoroacetic acid (95% aqueous solution) was added as a catalyst and vortexed again to obtain a DPCM sol-gel solution. A 10-cm-long stainless steel wire (0.3 mm diameter) was immersed at one end in a hydrofluoric acid solution for 30 minutes. The wire was then rinsed with ultrapure water to remove surface acid impurities, allowed to air dry at room temperature, and then vertically immersed in the prepared sol-gel solution and rotated 20 times. The fiber was removed and dried at room temperature for 2 minutes. This process was repeated six times to obtain a DPCM-coated fiber. Finally, the coated fiber was dried at room temperature for 24 hours and then placed in a 280°C oven for 2 hours. Before use, it was assembled into a 1 mL microsyringe and activated at the gas chromatography inlet at 280°C for 2 h under the protection of nitrogen to prepare a solid phase microextraction device.

[0022] like Figure 1 The FT-IR characterization diagram of COF, FPBA and TAPT is shown at 3410 cm -1 and 1705 cm -1 The stretching vibration peaks of OH and C=O of FPBA are at 3463 cm -1 and 815 cm -1 The NH stretching vibration peak of TAPT and the ring plane bending vibration absorption peak of triazine unit are located at 815 cm. In the synthesized COF, it can be clearly seen that the OH, C=O, and NH peaks disappear. -1 The ring plane bending vibration absorption peak of the triazine unit at 744 cm -1 , 1594 cm -1 The characteristic peaks of six-membered B3O3 boron-oxygen heterocycle and imine appear at , which further proves the successful synthesis of COF.

[0023] like Figure 2 (a) is a SEM image of a COF, and (b) is a SEM image of DPCM. Comparing the two, the latter shows a distinct wrinkled surface morphology, indicating a rougher surface, which increases its specific surface area and provides more active sites. (c) is a SEM image of a DPCM-coated fiber, demonstrating that DPCM is thoroughly mixed with the sol-gel solution and evenly coated on the stainless steel wire surface. Example 2

[0024] This example investigates the effect of an SPME device coated with DPCM prepared at different carbonization temperatures on the extraction efficiency of PAEs in water samples.

[0025] The SPME device was prepared according to the method of Example 1, except that the COF material was placed in a tube furnace and carbonized at 500, 600, 700, and 800 °C for 2 h under nitrogen. Figure 3 As shown, when the carbonization temperature is 700°C, the extraction efficiency is the best, so the present invention selects the optimal carbonization temperature as 700°C. Example 3

[0026] This embodiment provides a method for extracting PAEs from a water sample using the SPME device described in Example 1, comprising the following steps:

[0027] 20 mL of 100 μg / L PAEs sample solution was transferred to a headspace vial and placed in a 90°C magnetic stirring water bath. The SPME device was inserted into the headspace vial and headspace extraction was performed for 25 minutes. After the extraction was completed, the SPME device was removed and inserted into the gas phase inlet. Thermal desorption was performed at 290°C for 4 minutes under nitrogen assistance. The chromatogram after extraction is shown in Figure 1. Figure 4 Five distinct chromatographic peaks were observed: diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), dipentyl phthalate (DPP), benzyl butyl phthalate (BBP), and dioctyl phthalate (DOP). In contrast, only the solvent peak was observed in the chromatogram obtained by direct injection without extraction, demonstrating that the established method is capable of detecting trace amounts of phthalates in water samples.

[0028] Comparative Example

[0029] In order to demonstrate the extraction performance of the SPME device coated with DPCM for PAEs, an SPME device coated with COF was prepared in this comparative example: 100 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and 130 mg of 4-formylphenylboronic acid (FPBA) were weighed and dissolved in 10 mL of a 1:1 dioxane and mesitylene solution. The mixture was ultrasonically mixed and the resulting solution was transferred to a reactor. The reaction was then placed in a 120°C oven for 72 h, cooled to room temperature, centrifuged, washed, and dried to obtain the COF material.

[0030] To a centrifuge tube, 100 μL of dichloromethane, 100 μL of methyltrimethoxysilane, 100 μL of polydimethylsiloxane, and 30 mg of COF were added and vortexed to mix thoroughly. Subsequently, 80 μL of trifluoroacetic acid (95% aqueous solution) was added as a catalyst and vortexed again to obtain a COF sol-gel solution. A 10-cm-long stainless steel wire (0.3 mm diameter) was immersed at one end in a hydrofluoric acid solution for 30 minutes. The surface acid impurities were then washed with ultrapure water and allowed to air dry at room temperature. The wire was then vertically immersed in the prepared sol-gel solution and rotated 20 times. The wire was then removed and dried at room temperature for 2 minutes. This process was repeated six times to obtain a COF-coated fiber. Finally, the coated fiber was dried at room temperature for 24 hours and then placed in a 280°C oven for 2 hours. Before use, it was assembled into a 1 mL microsyringe and activated at 280°C for 2 h at the gas chromatography inlet under nitrogen protection to prepare a COF-coated SPME device. This device and the DPCM-coated SPME device described in Example 1 were used to extract PAEs in water. The results are shown in Figure 2. Figure 5 As shown in the figure, it can be seen that the peak area of ​​PAEs extracted by the DPCM-coated SPME device is much larger than that of the COF-coated SPME device, indicating that the DPCM-coated SPME device has better extraction efficiency.

Claims

1. A method for preparing an SPME device with a DPCM coating, characterized in that: The following steps are involved: S1. A certain amount of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4-formylphenylboronic acid were weighed and dissolved in 10 mL of dioxane and mesitylene solution. The mixture was ultrasonically mixed and the resulting solution was transferred to a reaction vessel. The mixture was then placed in an oven for reaction. The mixture was then cooled to room temperature, centrifuged, washed, and dried to obtain a COF material. Finally, the COF material was placed in a tube furnace and calcined under a nitrogen atmosphere for 2 h. After cooling to room temperature, the mixture was washed, centrifuged, and dried to obtain the DPCM. 100 mg of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 130 mg of 4-formylphenylboronic acid were added, and the volume ratio of dioxane to mesitylene was 1:

1. The oven temperature was 120°C, the reaction time was 72 hours, and the temperature of the tube furnace was 500-800°C. S2. 100 μL of dichloromethane, 100 μL of methyltrimethoxysilane, 100 μL of polydimethylsiloxane, and 30 mg of DPCM were added to a centrifuge tube and vortexed to mix thoroughly. Subsequently, 80 μL of a 95% aqueous solution of trifluoroacetic acid was added as a catalyst and vortexed again to obtain a DPCM sol-gel solution. A stainless steel wire was immersed at one end in a hydrofluoric acid solution and then cleaned with ultrapure water to remove surface acid impurities. The wire was allowed to dry at room temperature and then vertically immersed in the sol-gel solution prepared above and rotated 20 times. The wire was then removed and dried at room temperature for 2 minutes. This operation was repeated 6 times to obtain a DPCM-coated fiber. The coated fiber was dried at room temperature for 24 hours and then placed in a 280°C oven for 2 hours. Before use, it was assembled into a 1 mL microsyringe and activated at a gas chromatography inlet at 280° C. for 2 h under nitrogen protection to prepare a solid phase microextraction device; the solid phase microextraction device was used for extraction analysis of PAEs in water samples.

2. The method for preparing an SPME device with DPCM as a coating according to claim 1, characterized in that: The diameter of the stainless steel wire fiber is 0.3 mm and the coating length is 1.4 cm.

3. The use of a solid phase microextraction device prepared by the method for preparing a SPME device with a DPCM coating according to claim 1 in the extraction of PAEs in water, characterized in that: The technical solutions adopted are as follows: 20 mL of PAEs sample solution was transferred to a headspace bottle, placed in a 90°C magnetic stirring water bath, and the SPME device was inserted into the headspace bottle. After 25 minutes of headspace extraction, the SPME device was removed and inserted into the gas phase inlet. Thermal desorption was performed at 290°C under nitrogen assistance to achieve extraction analysis of PAEs in the water sample.

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