24中英文雙語(yǔ)外文文獻(xiàn)翻譯成品基于共價(jià)有機(jī)框架的磁性吸附劑的多環(huán)芳烴固相萃取及其hplc定量字符連接

1、<p>　　A covalent organic framework-based magnetic sorbent for solid phase extraction of polycyclic aromatic hydrocarbons,and its hyphenation to HPLC for quantitation</p><p>　　外文標(biāo)題：A covalent organic fra

2、mework-based magnetic sorbent for solid phase extraction of polycyclic aromatic hydrocarbons, and and its hyphenation to HPLC for quantitation</p><p>　　外文作者：Rong Wang ,Zilin Chen</p><p>　　文獻(xiàn)出處:《

3、Microchimica Acta》 , 2017 (5751) :1-8</p><p>　　英文4589單詞， 24889字符，中文7792漢字。</p><p>　　此文檔是外文翻譯成品，無(wú)需調(diào)整復(fù)雜的格式哦！下載之后直接可用，方便快捷！只需二十多元。</p><p><b>　　Abstract </b></p><

4、p>　　A novel covalent organic framework based mag- netic adsorbent was developed for magnetic solid phase ex- traction (MSPE) of polycyclic aromatic hydrocarbons (PAHs). Covalent organic framework-LZU1 (= Lan Zhou Univ

5、ersity-1) was covalently immobilized onto polyethyleneimine-functionalized magnetic nanoparticles (COF-LZU1@PEI@Fe3O4), and the resulting material was characterized by transmission electron microscopy and Fourier transfo

6、rm infrared spectroscopy. The effects of the pH value of sample sol</p><p>　　Keywords Covalent organic framework . COF-LZU1 . Magnetic solid phase extraction . Environmental analysis . Trace analysis . HPLC&

7、lt;/p><p>　　Introduction</p><p>　　Covalent organic frameworks (COFs) are a class of crystalline porous materials that consist of light elements (C, H, B, N, O etc.) and are connected through strong

8、 covalent bonds [1–7]. These materials possess much fascinating properties including high specific surface area, excellent thermal stability, high porosity, and low density. With these unique properties, COFs have arouse

9、d intensive interest of scientists for the great</p><p>　　potential application in diverse areas [2, 4], such as gas storage [8–10], gas adsorption [11, 12], photoelectricity [13, 14], ca- talysis [15, 16] a

10、nd chromatographic separation [17–19]. However, there are still few reports focusing on their perfor- mance in the field of sample pretreatment. Metal–organic</p><p>　　frameworks (MOFs) are another novel cla

11、ss of porous mate- rials similar to COFs, which have shown to be promising materials as sorbents for sample preparation in many pioneer works [20–24]. As the analogues of MOFs, COFs should possess great application poten

12、tial in sample preparation.</p><p>　　Hydrazone covalent organic frameworks have been synthe- sized and applied to the solid-phase microextraction (SPME) of pyrethroids [25] and pesticides [26] in vegetables.

13、 Therefore, it is possible to develop the application of COFs as promising adsorbent in sample pretreatment.</p><p>　　Since the first discovery of COF materials in 2005 [1], a variety of COFs have been repor

14、ted. Imine-linked COF-LZU1 (Lan Zhou University-1) was first designed and synthesized by Wang’ group in 2011 [15], which was constructed with 1,3,5-triformylbenzene and 1,4-diaminobenzene through Schiff base reaction. CO

15、F-LZU1 has a two-dimensional (2D) layered-sheet structure and possesses large number of benzene rings and imine groups. Unlike boron-containing COFs that linked by boroxine or boronate-ester </p><p>　　Sample

16、 preparation is a critical step prior to analysis, espe-cially when complex samples are present. Over the past few decades, many new sample pretreatment techniques with low solvent consumption and low sample handling hav

17、e been de- veloped and applied to extract target compounds from different matrices [27, 28]. Among these techniques, magnetic solid-phase extraction (MSPE) has attracted increasing atten- tion due to its large adsorption

18、 capacity and high extraction efficiency [29]. Additio</p><p>　　Polycyclic aromatic hydrocarbons (PAHs) are well-known environment pollutants, which are considered to be carcino- genic and mutagenic to human

19、 beings. It is of great impor- tance to monitor and control the amount of PAHs in environment. Since the concentration of PAHs in environmental samples is usually in trace levels, it is necessary to enrich PAHs by effici

20、ent sample pretreatment method before instrumental analysis [31–34]. Considering the properties of COF-LZU1 and PAHs, COF-LZU1 based MSPE</p><p>　　Herein, in this work, we reported the fabrication of a novel

21、 COF-LZU1 functionalized MNPs (COF- LZU1@PEI@Fe3O4) and its application for the MSPE of PAHs. Fe3O4 nanoparticles were first coated with PEI, then COF-LZU1 was grown on the surface of MNPs attributing to the covalent bon

22、ding between the PEI layer and COF- LZU1. The morphology and surface properties of nanoparticles were characterized by transmission electron microscopy (TEM) and Fourier-transformed infrared spectroscopy (FT-IR). COF-LZU

23、</p><p>　　Experimental</p><p>　　Chemicals and materials</p><p>　　1,3,5-Triformylbenzene, 1,4-diaminobenzene, pyrene (PYR), benzo[a]pyrene (B[a]PY), phenanthrene, anthracene, naph- t

24、halene, 1-naphthol were purchased from Sigma–Aldrich (MO, USA, www.sigma-aldrich.com). Fluoranthene (FLU), benz[a]anthracene (B[a]AN), benzo[a]fluorathene (B[a]FL), dibenz[a,h]anthracene (D[a,h]AN) were obtained from TCI

25、 (Shanghai, China, www.tcichemicals.com). 4-Phenylphenol, 4-vinylbiphenyl and 1,4-dioxane, polyethyleneimine (PEI, Mw 70,000 g mol?1, 50% (w/v) aqueous solution) we</p><p>　　Instrumentation</p><p&

26、gt;　　The chromatographic analysis was performed by a Shimadzu 20A HPLC system (Tokyo, Japan, http://www.shimadzu.com. cn), which equipped with two 20A pumps, a six-port valve, a 20A UV detector, and a 10A fluorescent det

27、ector. The chromatographic separation was carried out by a C18 column (150 mm × 4.6 mm i.d., 5 μm particle size, GL Science, Tokyo, Japan, www.shimadzu-gl.com.cn). The mobile phase</p><p>　　consisted of

28、 methanol and water (89/11, v/v) and the flow rate was 1.0 ml min?1. The detection wavelength of fluorescent detector was set at 290 nm (exiting wavelength) and 430 nm (emission wavelength), while the detection wavelengt

29、h of UV detector was set at 254 nm. The column temperature for HPLC separation was set at 30 °C.</p><p>　　Fourier-transformed infrared spectroscopy (FT-IR) charac- terization was performed on Thermo Nex

30、us 470 FT-IR system (MA, UAS, http://www.thermonexus.com). The transmission electron microscopy (TEM) image was obtained by a JEM-2100 (HR) transmission electron microscope (TEM) (JEOL, Tokyo, Japan, https://www.jeol.co.

31、jp/en/).</p><p>　　Preparation of COF-LZU1@PEI@Fe3O4</p><p>　　PEI@Fe3O4 was prepared following Amal’s method [30]. Briefly, FeCl2?4H2O (0.7 g) was firstly dissolved in 80 mL of distilled water. T

32、hen 10 mL of KNO3 (2.0 M), 10 mL of NaOH (1.0 M) and PEI (1.7 g) were added to this solution sequentially under nitrogen atmosphere. After being stirred for 2 h at 90 °C, the synthesized nanoparticles were collected

33、 by a magnet, followed by washing with water for several times.</p><p>　　1,3,5-Triformylbenzene (3 mg), 1,4-diaminobenzene(3 mg) were dissolved in 3 mL of 1,4-dioxane and followed by the addition of 60 μL of

34、 3 M aqueous acetic acid. PEI@ Fe3O4 (100 mg) were suspended in above solution with ultrasonication. For modification of COF-LZU1, the temper- ature was rose to 150 °C and reacted for 24 h. Finally, the COF-LZU1@PEI

35、@Fe3O4 were washed with ethanol thor- oughly and dried in the oven (60 °C).</p><p>　　COF-LZU1@PEI@Fe3O4 based MSPE procedures</p><p>　　PAHs standard were dissolved in 20 mM phosphate buffer

36、 (pH 9, containing 1% acetonitrile, v/v) at certain concentra- tion. COF-LZU1@PEI@Fe3O4 (5 mg) were carefully weighed and mixed with 20 mL of sample solution. The mix- ture was stirring for 30 min with the assistant of a

37、 magnetic stirring apparatus (two bottles containing the mixture and stir ring bar were placed together and stirring). Before collection of nanoparticles, the stirring bar was removed by a magnet under stirring. After th

38、at, th</p><p>　　Sample preparation</p><p>　　To investigate the application in real samples of this method,water and soil samples were collected. Tap water was obtained from laboratory and lake w

39、ater was from East Lake, Wuhan. Water samples were filtered through 0.45 μm nylon membrane and then added 1% acetonitrile (v/v). Two soil samples were collected, one was from lakeshore of East Lake (soil A) and the other

40、 one was from the land beside a local road in Wuhan (soil B). The soil samples were firstly dried and grounded into powder. 5 g so</p><p>　　Results and discussion</p><p>　　Choice of materials<

41、;/p><p>　　COF-LZU1 possesses many remarkable characteristics: ex- cellent thermal stability, low density, high surface area, and permanent porosity. The high surface area and porosity can improve the loading ca

42、pacity of adsorbent. It is highly stable in water and most organic solvents [15]. COF-LZU1 is pre- pared from 1,3,5-triformylbenzene and 1,4-diaminobenzene through Schiff base reaction. There are rich benzene rings and i

43、mine groups in its structure. Thus it can offer strong π stacking interaction an</p><p>　　Preparation of COF-LZU1@PEI@Fe3O4</p><p>　　A COF-LZU1-modified magnetic nanoparticles was prepared in th

44、is work, as shown in Fig. 1. Fe2+ was firstly formed Fe(OH)2 in the presence of NaOH, then heated at 90 °C after the addition of PEI solution. During the formation of Fe3O4 nanoparticles, PEI was self-assembled on t

45、he surface via elec- trostatic interaction. Amino groups of PEI layer were active to participate the formation of COF-LZU1 through the Schiff- base reaction, resulting in the immobilization and growth of COF -LZU1 on mag

46、neti</p><p>　　The structure and the thickness of COF-LZU1 would affect the interaction between the target compounds and the COF-LZU1@PEI@Fe3O4. Some parameters that can affect modi- fication of COF-LZU1 were

47、 investigated. These include the reaction temperature, the concentration of ligands and the volume of aqueous acetic acid as can be seen in the supporting information. The optimized conditions were selected for the coati

48、ng of COF-LZU1 as follows: reaction temperature: 150 °C, concentration of ligands: 1 mg</p><p>　　Characterization of COF-LZU1@PEI@Fe3O4</p><p>　　FT-IR spectroscopy was employed to character

49、ize the functional moieties of the COF-LZU1@PEI@Fe3O4 (Fig. 2). The absorption band at 581 cm?1 is assigned to stretching vibration of Fe-O for Fe3O4 nanoparticles. </p><p>　　The absorption bands at 3404 cm

50、?1,1688 cm?1 are caused by stretching of N-H and C = O, respectively. The peak at 1614 cm?1 corresponds to the C = N stretching for imine. The peaks at 614 cm? 1 , 679 cm?1,831 cm?1 are characteristic absorption of C-H f

51、or substituted aromatic. The FT-IR analysis result indicates the formation of COF-LZU1, suggesting the COF-LZU1 has been successfully modified on the sur- face of Fe3O4.</p><p>　　The morphology of PEI@Fe3 O4

52、 and COF-LZU1@PEI@Fe3O4 nanoparticles were investigated by TEM. As shown in Fig. 3, the obtain nanoparticles are cubic in shape and well-dispersed, with a mean diameter about 40 nm (average face-centered diagonal). It ca

53、n be seen that the surface of PEI@Fe3O4 was smooth (Fig. 3b). After modification of COF-LZU1, a thin and rough polymer layer is observed (Fig. 3d), indicating that the COF-LZU1 is immobilized onto the surface of PEI@Fe3O

54、4.</p><p>　　Optimization of sampling conditions</p><p>　　As mentioned above, the aromatic rings and imine groups of COF-LZU1 can offer strong π-interaction and hydrophobic effect with the analyt

55、es. Therefore, six PAHs compounds were selected to test the enrich- ment performance of COF-LZU1@PEI@Fe3O4 due to their hydrophobic properties and demands of low- content determination. To achieve higher extraction effi-

56、 ciency, the following parameters were optimized: (a) pH of sample solution; (b) acetonitrile content; (c) extrac- tion time; (d) sampling volu</p><p>　　Enrichment performance of COF-LZU1@PEI@Fe3O4</p>

57、<p>　　Extraction performance of COF-LZU1@PEI@Fe3O4 was evaluated under the optimized conditions. Sample solu- tion containing 0.5 ng mL?1 was extracted by COF- LZU1@PEI@Fe3O4, then analyzed with HPLC (Fig. 4b). Fo

58、r comparison, the six PAHs standard solution (0.5 ng mL?1) was directly injected into HPLC system for analysis (Fig. 4a). Significant extraction efficiency is observed for COF-LZU1@PEI@Fe3O4. Enrichment fac- tors (FE) of

59、 COF-LZU1@PEI@Fe3O4 towards PAHs were determined and calculated by: FE = </p><p>　　B[a]AN,86 for B[a]FL,86 for B[a]PY, 90 for D[a,h]AN (theoretical enrichment factor is 100-fold), as shown in Table S1.</p

60、><p>　　To further understand the adsorption mechanism of COF-LZU1@PEI@Fe3O4 for analytes, other PAHs and aromatic compounds were also loaded onto MSPE, the extraction factors are listed in Table S1. FE is posit

61、ively related mostly to the number of condensed rings and log KOW of compounds, for example, FE(B[a]PY) ?FE(PYR) ?FE(phenanthrene), which suggests that the adsorption of COF-LZU1@PEI@Fe3O4 is mainly attributed to π stack

62、- ing and hydrophobic interaction. However, 4- phenylphenol and 1-naphthol wi</p><p>　　Reusability of COF-LZU1@PEI@Fe3O4</p><p>　　Reusability is an important factor for evaluating the efficiency

63、 of sorbents. In the process of MSPE, the coating of COF-LZU1@PEI@Fe3O4 might be destroyed during stirring and ultrasonication, further affected the reuse of COF- LZU1@PEI@Fe3O4. In order to investigate the reusability,

64、COF-LZU1@PEI@Fe3O4 were used six times for the extraction of PAHs (the nanoparticles were washed with ace- tonitrile for three times and dried in the oven before the next use). The conservation rate was calculated by<

65、/p><p>　　Analytical performance</p><p>　　The COF-LZU1@PEI@Fe3O4-based MSPE was coupled with HPLC and applied to determination of PAHs in aqueous samples. Parameters for analytical performance inclu

66、ding lin- earity, limit of detection (LOD), limit of qualification (LOQ) and the repeatability were investigated, the results are listed in Table S2. Over the range of 2–1000 pg mL?1 for FLU, B[a]AN and B[a]FL, 50–5000 p

67、g mL?1 for PYR, 0.5– 500 pg mL?1 for B[a]PY, 10–2000 pg mL?1 for D[a,h]AN, all six PAHs exhibit good linearity, with correla</p><p>　　This method is compared with other MSPE methods for the enrichment and de

68、termination of PAHs [32, 34–38]. As shown in Table 1, the sensitivity of this method is comparable or superior to other MSPE methods with less amount of ad- sorbent and lower sample volume consumption.</p><p&g

69、t;　　Application in environmental samples</p><p>　　The MSPE-HPLC method was applied to enrich and determine of PAHs in real samples. PAHs are potent carcinogenic compounds, which distribute widely in environm

70、ent such as water, soil and air. Therefore, two water samples and two soil samples were collected as environmental samples. The chro- matograms were shown in Fig. 5, and the results are listed in Table 2. As shown in Fig

71、. 5a, FLU and B[b]FL are found in tap water after extraction. FLU, B[b]FL and B[a]PY are de- tected in lake water after MSP</p><p>　　in the future.</p><p>　　Recoveries in environmental samples w

72、ere tested by spik- ing with six PAH standards at 50 pg mL?1 for two water samples, 80 ng g?1 and 40 ng g?1 for two soil samples. By calculating the mean value of three duplicates, spiked recov- eries in water samples ar

73、e in the range of 90.9–107.8%, re- coveries in soil samples are in the range of 85.1–105.0%. The results of recovery show good accuracy of the method for determination of PAHs in environmental samples.</p><p&g

74、t;　　Conclusion</p><p>　　In this study, a novel COF-LZU1 functionalized magnetic nanoparticles (COF-LZU1@PEI@Fe3O4) was successfully synthesized and applied to magnetic solid phase extraction for the first ti

75、me. The prepared COF-LZU1@PEI@Fe3O4 showed good stability and reusability. The COF- LZU1@PEI@Fe3O4 based MSPE exhibited high extraction efficiency towards PAHs, which was mainly attributed to strong π stacking and hydrop

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