Preparation method and application of novel graphene oxide-based needle trap micro-extraction device
By preparing GrO@MIL-101(Cr) composite materials as coatings, the problems of insufficient durability and extraction performance of graphene oxide-based coating devices were solved, and efficient extraction and analysis of trace pollutants were achieved.
Patent Information
- Application Number
- CN202510572801.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing technology, solid-phase microextraction devices with graphene oxide-based coatings have deficiencies in durability and extraction performance, making it difficult to meet the requirements for efficient extraction of trace pollutants.
GrO@MIL-101(Cr) composite material was used as the coating. Graphene oxide was combined with MIL-101(Cr) during the preparation process to form irregular composite crystals, which increased the specific surface area. The coated fibers were then prepared into stainless steel needles for the preparation of a novel needle trap microextraction device (NTED) and combined with gas chromatography for extraction analysis.
The extraction performance and analytical sensitivity are improved, the problems of insufficient durability and extraction performance in the existing technology are solved, and the efficient extraction of trace pollutants is achieved.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of sample pretreatment, and particularly relates to a preparation method of a GrO@MIL-101(Cr)-coated NTED and application thereof. BACKGROUND
[0002] Graphene oxide (GO) has a large surface area, a double-sided polyaromatic skeleton, abundant oxygen-containing functional groups, and a large pi electron structure, and is considered to be an ideal adsorbent for solid-phase extraction (SPE) and solid-phase microextraction (SPME). In recent years, in order to further improve the extraction performance and selectivity of GO for target substances, various functionalized GO materials have been developed, such as polymer, MOF, COF, nanomaterial, magnetic material and molecularly imprinted polymer (MIP) functionalized GO, which are widely used in the fields of SPE and SPME. At present, SPE and SPME are used as main sample pretreatment techniques for the analysis of various organic pollutants, and with the continuous progress of the pretreatment technology, new more efficient and environmentally friendly extraction techniques have been developed.
[0003] Needle trap microextraction (NTME) is a highly efficient sample preparation technique proposed by Pawliszyn et al. on the basis of solid-phase microextraction (SPME). Without other auxiliary instruments, after sampling is completed, the extraction needle can be directly connected to a gas-tight syringe containing high-purity nitrogen, and inserted into the injection port of a gas chromatograph, and the thermally desorbed analytes are transported to the chromatographic column by the carrier gas flow for online analysis. This technique not only simplifies the experimental process and reduces the operating cost, but also promotes the possibility of on-site rapid detection through its miniaturized design, ensures the efficiency and environmental protection of the detection process, and has great potential and application value in the fields of environmental monitoring, food safety, drug analysis and the like. The core part of the NTED is that the adsorbent or coating fiber is filled in a specially designed stainless steel needle. Compared with the traditional SPME technology, the durability of the device is significantly improved, and the common problem of coating falling off is effectively avoided, thereby ensuring a longer service life and more stable extraction performance.
[0004] To this end, a new type of graphene oxide-based composite material coating needle trap microextraction device is prepared, which is combined with gas chromatography for extraction and analysis of trace PCBs in water samples. SUMMARY
[0005] The application aims to provide a preparation method of a GrO@MIL-101(Cr)-coated NTED and application thereof.
[0006] The first object of the application is to provide a preparation method of a GrO@MIL-101(Cr)-coated NTED, and the technical scheme adopted is as follows:
[0007] S1. Take 0.22 g of graphene oxide and dissolve it in 24 mL of deionized water, mix uniformly by ultrasonic, prepare a suspension of GrO, then add 2 g of cadmium nitrate and 1.66 g of terephthalic acid, dissolve by ultrasonic and transfer to a reaction kettle, then put it into a 220℃ oven for 8h, cool to room temperature, centrifuge, wash, vacuum dry, and get GrO@MIL-101(Cr);
[0008] S2. Add 100 μL of dichloromethane, 100 μL of methyltrimethoxysilane, and 100 μL of polydimethylsiloxane into the centrifuge tube, mix uniformly, then add 80 μL of 5% trifluoroacetic acid and vortex, to obtain a sol-gel solution; take a stainless steel wire with a diameter of 0.3 mm, etch one end (5 cm) in a hydrofluoric acid solution, wash it with ultrapure water, dry it at room temperature, then immerse it in the above prepared sol-gel solution, slowly pull it out, and rotate it 3 times in the GrO@MIL-101(Cr) powder, repeat the process three times, to obtain a GrO@MIL-101(Cr) coated fiber, dry it at room temperature for 24 h, then put it into a 280℃ oven for 3 h; before use, assemble it into a 21G stainless steel needle, and age it in a gas chromatography inlet at 280℃ for 2 h under the protection of nitrogen, to obtain an NTED.
[0009] The second object of the application is to apply the prepared NTED to the extraction of PCBs in water samples, characterized in that the technical scheme is as follows:
[0010] Transfer 20 mL of a PCB sample solution into a headspace bottle, place it in a 75℃ magnetic stirring water bath, insert the NTED into the sample bottle to a position 1 cm above the liquid surface. Connect one end of the NTED to a peristaltic pump, and connect the other end of the peristaltic pump to a needle and insert it below the liquid surface, extract for 25 min, remove the NTED, insert it into a gas chromatography inlet, and perform pyrolysis at 270℃ under the assistance of nitrogen, to realize the extraction and analysis of PCBs in water samples.
[0011] The beneficial effects of the application compared with the prior art are:
[0012] After the MIL-101(Cr) is compounded with GrO, the obtained GrO@MIL-101(Cr) has a smaller particle size, a more irregular composite crystal, a rougher surface, and a larger specific surface area compared with MIL-101(Cr); the NTED prepared by using it as a coating has better extraction performance, and can improve the analysis sensitivity of PCBs. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 The infrared spectrum (FT-IR) of monomers GrO, MIL-101(Cr), and GrO@MIL-101(Cr).
[0014] Figure 2 (a) is a scanning electron microscope (SEM) image of GrO, (b) is a SEM image of MIL-101(Cr), (c) is a SEM image of GrO@MIL-101(Cr) coated fiber.
[0015] Figure 3 are chromatograms of PCBs before and after extraction.
[0016] Figure 4 are chromatograms of PCBs extracted by GrO, MIL101-(Cr) and NTED coated with GrO@MIL-101(Cr).
Claims
1. A method for preparing NTED with GrO@MIL-101(Cr) coating, characterized in that: The following steps are involved: P1. A certain mass of graphene oxide (GrO) was weighed and added to 24 mL of deionized water. Ultrasonic mixing was performed to prepare a GrO suspension. Cadmium nitrate nonahydrate and terephthalic acid were then added and ultrasonically dissolved. The suspension was then transferred to a reactor and heated in an oven for reaction. After the reaction, the suspension was cooled to room temperature, centrifuged, washed, and vacuum-dried to obtain GrO@MIL-101(Cr). P2. Dichloromethane, methyltrimethoxysilane, and polydimethylsiloxane were added to a centrifuge tube and mixed thoroughly. 5% trifluoroacetic acid was then added and vortexed to obtain a sol-gel solution. A stainless steel wire was taken, one end was immersed in hydrofluoric acid for etching, then cleaned with ultrapure water, dried at room temperature, and then immersed in the prepared sol-gel solution. The wire was slowly withdrawn and rotated in GrO@MIL-101(Cr) powder. This process was repeated three times to obtain GrO@MIL-101(Cr)-coated fibers. The fibers were dried at room temperature for 24 h and then oven-dried at 280°C for 3 h. Before use, they were assembled into a 21G stainless steel needle and aged at a 280°C gas chromatography inlet for 2 h under nitrogen to obtain NTED.
2. The method for preparing NTED with GrO@MIL-101(Cr) coating according to claim 1, characterized in that: The added mass of graphene oxide was 0.22 g, the mass of cadmium nitrate nonahydrate was 2.00 g, and the mass of terephthalic acid was 1.66 g.
3. The method for preparing NTED with GrO@MIL-101(Cr) coating according to claim 1, characterized in that: The oven temperature was 220 °C and the reaction time was 8 h.
4. The method for preparing NTED with GrO@MIL-101(Cr) 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 5 cm.
5. The solid phase microextraction device prepared according to claim 1 is used for extracting PCBs in water, characterized in that: The technical solutions adopted are as follows: A 20 mL PCB sample solution was transferred to a headspace vial and placed in a 75°C magnetic stirring water bath. The NTED was inserted into the sample vial, 1 cm above the liquid level. The NTED was connected to one end of a peristaltic pump, and the other end of the peristaltic pump was connected to a blank needle and inserted below the liquid level. Extraction was performed for 25 minutes. The NTED was then removed and inserted into the gas phase inlet. Thermal desorption was performed at 270°C under nitrogen assistance to extract and analyze PCBs in the water sample.