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1.
In this study, poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) were synthesized by the covalent functionalization of MWCNTs with hydroxyl-terminated PEG chains. For the first time, functionalized product of PEG-g-MWCNTs was used as selective stationary phase to prepare the sol-gel solid-phase microextraction (SPME) fiber in combination with gas chromatography-flame ionization detector (GC-FID) for the determination of ultra-trace levels of benzene, toluene, ethylbenzene and o-xylene (BTEX) in real water samples. The PEG-g-MWCNTs were characterized by Fourier transform infrared spectra and also thermo-gravimetric analysis, which verified that PEG chains were grafted onto the surface of the MWCNTs. The scanning electron micrographs of the fiber surface revealed a highly porous structure which greatly increases the surface area for PEG-g-MWCNTs sol-gel coating. This fiber demonstrated many inherent advantages, the main being the strong anchoring of the coating to the fused silica resulting from chemical bonding with the silanol groups on the fused-silica fiber surface. The new PEG-g-MWCNTs sol-gel fiber is simple to prepare, robust, with high thermal stability and long lifetime, up to 200 extractions. Important parameters influencing the extraction efficiency such as desorption temperature and time, extraction temperature, extraction time, stirring speed and salt effect were investigated and optimized. Under the optimal conditions, the method detection limits (S/N=3) were in the range of 0.6-3 pg mL(-1) and the limits of quantification (S/N=10) between 2 and 10 pg mL(-1). The relative standard deviations (RSDs) for one fiber (repeatability) (n=5) were obtained from 4.40 up to 5.75% and between fibers or batch to batch (n=3) (reproducibility) in the range of 4.31-6.55%. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples at 20 pg mL(-1) were from 90.21 to 101.90%.  相似文献   

2.
A novel solid-phase microextraction (SPME) Pt fiber coated with single-walled carbon nanotubes (SWCNTs) was prepared by electrophoretic deposition (EPD) and applied to the determination of phenols in aqueous samples by direct immersion (DI)-SPME-HPLC-UV. The results revealed that EPD was a simple and reproducible technique for the preparation of SPME fibers coated with SWCNTs without the use of adhesive. The obtained SWCNT coating did not swell in organic solvents nor strip off from substrate, and possessed high mechanical strength due to the strong Van der Waals attractions between the surfaces of the SWCNTs. The prepared SPME fiber was conductive since both SWCNT coating and Pt wire were conductive. Using Pt wire as substrate, the fiber was unbreakable. Owing to the presence of oxygenated groups on SWCNTs and the high surface area of SWCNTs, the SWCNT fiber was similar to or superior to commercial PA fiber in extracting the studied phenols from aqueous sample. A durability of more than 80 analyses was achieved for one unique fiber. Under optimized conditions, the detection limits for the phenols varied between 0.9 and 3.8 ng/mL, the precisions were in the range of 0.7–3.2% (n = 3), and linear ranges were within 10 and 300 ng/mL. The method was successfully applied to the analysis of spiked seawater and tap water samples with the recoveries from 87.5 to 102.0%.  相似文献   

3.
Fang Wu  Wanping Lu  Wei Liu 《Talanta》2010,82(3):1038-57
Using a single-walled carbon nanotubes (SWCNTs) as stationary phase of solid-phase microextraction (SPME) fibers, a simple, low cost and environmentally friendly method for extraction of 13 pesticides in Tea samples has been developed following gas chromatography-mass spectrometric determination. Potential factors affecting the extraction efficiency were investigated and optimized, including extraction and desorption time, extraction temperature, stirring rate, solution pH and ionic strength. Under optimized conditions, the linearity of the developed method was in the range of 0.125-25 ng/mL with correlation coefficients greater than 0.9928 and the limits of detections (LODs) were 0.027-0.23 ng/mL (S/N = 3). Meanwhile, the relative standard deviations (RSDs) for five successive measurements with single fiber, fiber-to-fiber, day-to-day were 2.3-13.0, 8.2-14.6 and 4.1-12.5%, respectively, indicating good reproducibility of the proposed method. The fiber had high extraction efficiency for studied pesticides in comparison with commercial poly(dimethylsiloxane) (PDMS) and polyacrylate (PA) fibers and could be used for more than 70 times without decrease of efficiency. The developed method was successfully applied for the analysis of real samples including green Tea, oolong Tea, white Tea, and flower Tea, and the recoveries of the pesticides spiked in these samples ranged from 75.1 to 118.4%. Chlorfenapyr and λ-cyhalothrin were found in the Tea samples bought randomly from local market. The results demonstrated that the developed SWCNTs-SPME method was a simple, efficient pretreatment and enrichment procedure for pesticides in complex matrices.  相似文献   

4.
Short-term solid-phase microextraction (SPME) was performed to test a recently proposed semi-empirical model for the prediction of concentrations of analyte in water samples from the fibre-extracted mass without further calibration. The mass uptake rates obtained for benzene, toluene, ethylbenzene and p-xylene (BTEX) differ considerably from the before published, showing that interfibre comparability is a serious issue. The relative prediction errors are between -55% for benzene and +82% for p-dichlorobenzene under optimal conditions, i.e. they are by an order of magnitude higher than originally published. A sensitivity analysis shows the dominant influence of the estimated thickness of the diffusional boundary layer around the fibre on the concentration predicted. Empirical modification of the model equation for this parameter yields satisfactory results under the conditions tested for both BTEX and the selected chlorobenzenes.  相似文献   

5.
Chen L  Chen W  Ma C  Du D  Chen X 《Talanta》2011,84(1):104-108
A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes/polypyrrole (MWCNTs/Ppy) was prepared with an electrochemical method and used for the extraction of pyrethroids in natural water samples. The results showed that the MWCNTs/Ppy coated fiber had high organic stability, and remarkable acid and alkali resistance. In addition, the MWCNTs/Ppy coated fiber was more effective and superior to commercial PDMS and PDMS/DVD fibers in extracting pyrethroids in natural water samples. Under optimized conditions, the calibration curves were found to be linear from 0.001 to 10 μg mL−1 for five of the six pyrethroids studied, the exception being fenvalerate (which was from 0.005 to 10 μg mL−1), and detection limits were within the range 0.12-0.43 ng mL−1. The recoveries of the pyrethroids spiked in water samples at 10 ng mL−1 ranged from 83 to 112%.  相似文献   

6.
Feng J  Sun M  Xu L  Li J  Liu X  Jiang S 《Journal of separation science》2011,34(18):2482-2488
Multi-walled carbon nanotubes-coated solid-phase microextraction fiber was prepared by a novel protocol involving mussel-adhesive-protein-inspired polydopamine film. The polydopamine was used as binding agent to immobilize amine-functionalized multi-walled carbon nanotubes onto the surface of the stainless steel wire via Michael addition or Schiff base reaction. Surface properties of the fiber were characterized by field emission scanning electron microscope and X-ray photoelectron spectroscope. Six phenols in aqueous solution were used as model compounds to investigate the extraction performance of the fiber and satisfactory results were obtained. Limit of detection was 0.10 μg/L for 2-methylphenol (2-MP) and 4-methylphenol (4-MP), and 0.02 μg/L for 2-ethylphenol (2-EP), 4-ethylphenol (4-EP), 2-tert-butylphenol (2-t-BuP), and 4-tert-butylphenol (4-t-BuP), which were much lower than commercial fiber and fibers made in laboratory. RSDs for one unique fiber are in the range of 1.92-7.00%. Fiber-to-fiber (n=3) reproducibility ranges from 4.44 to 8.41%. It also showed very high stability and durability to acid, alkali, organic solvent, and high temperature. Real water sample from Yellow river was applied to test the reliability of the established solid-phase microextraction (SPME)-GC method and recoveries with addition level at 5 and 100 μg/L were in the range from 81.5 to 110.0%.  相似文献   

7.
A novel design of solid phase microextraction fiber containing carbon nanotube reinforced sol-gel which was protected by polypropylene hollow fiber (HF-SPME) was developed for pre-concentration and determination of BTEX in environmental waste water and human hair samples. The method validation was included and satisfying results with high pre-concentration factors were obtained. In the present study orthogonal array experimental design (OAD) procedure with OA(16) (4(4)) matrix was applied to study the effect of four factors influencing the HF-SPME method efficiency: stirring speed, volume of adsorption organic solvent, extraction and desorption time of the sample solution, by which the effect of each factor was estimated using individual contributions as response functions in the screening process. Analysis of variance (ANOVA) was employed for estimating the main significant factors and their percentage contributions in extraction. Calibration curves were plotted using ten spiking levels of BTEX in the concentration ranges of 0.02-30,000ng/mL with correlation coefficients (r) 0.989-0.9991 for analytes. Under the optimized extraction conditions, the method showed good linearity (0.3-20,000ng/L), repeatability, low limits of detections (0.49-0.7ng/L) and excellent pre-concentration factors (185-1872). The best conditions which were estimated then applied for the analysis of BTEX compounds in the real samples.  相似文献   

8.
A novel nanocomposite coating of poly(o‐toluidine) and oxidized multiwalled CNTs (MWCNTs, where CNTs is carbon nanotubes) was electrochemically prepared on a stainless‐steel wire. The applicability of the fiber was assessed for the headspace solid‐phase microextraction of benzene, toluene, ethylbenzene, and xylenes in aqueous samples followed by GC with flame ionization detection. In order to obtain an adherent and stable composite coating, several experimental parameters related to the coating process, such as polymerization potential and time, and the concentration of o‐toluidine and oxidized MWCNTs were optimized. The combination of MWCNTs and polymer in a nanocomposite form presents desirable opportunities to produce materials for new applications. The effects of various parameters on the efficiency of the headspace solid‐phase microextraction process, such as desorption temperature and time, extraction temperature and time, and ionic strength were also investigated. At the optimum conditions, LODs were 0.03–0.06 μg/L. The method showed linearity in the range of 0.5–300 μg/L with coefficients of determination >0.99. The intraday and interday RSDs obtained at a 5 μg/L concentration level (n = 5) using a single fiber were 1.2–5.2 and 3.2–7.5%, respectively. The fiber‐to‐fiber RSD (%; n = 3) at 5 μg/L was 6.1–9.2%.  相似文献   

9.
Multiple headspace-solid phase microextraction (MHS-SPME) is a recently developed technique for the quantification of analytes in solid samples that avoids the matrix effect. This method implies several consecutive extractions from the same sample. In this way, the total area corresponding to complete extraction can be directly calculated as the sum of the areas of each individual extraction when the extraction is exhaustive, or through a mathematical equation when it is not exhaustive. In this paper, the quantitative determination of benzene, toluene, ethylbenzene and xylene isomers (BTEX) in a certified soil (RTC-CRM304, LGC Promochem) and in a contaminated soil by multiple HS-SPME coupled to a gas chromatography-flame ionisation detector (GC-FID) is presented. BTEX extraction was carried out using soil suspensions in water at 30 degrees C with a 75 microm carboxen-polydimethylsiloxane (CAR-PDMS) fibre and calibration was carried out using aqueous BTEX solutions at 30 degrees C for 30 min with the same fibre. BTEX concentration was calculated by interpolating the total peak area found for the soils in the calibration graphs obtained from aqueous solutions. The toluene, ethylbenzene, o-xylene and m,p-xylene concentrations obtained were statistically equal to the certified values.  相似文献   

10.
The positively charged single walled carbon nanotubes (SWNTs~ ) were prepared by conjugating with-CONH-C_6H_(12)-NH_3~ . The double strand DNA(dsDNA) chains were loaded onto SWNTs~ via the electrostatic interactions.SWNTs~ shows improved loading efficiency (353.5μg/mg) toward dsDNA compared with that of charged free single walled carbon nanotubes (SWNTs) (82.9μg/mg).  相似文献   

11.
The present work reports preparation of ordered mesoporous carbon (OMC) film supported on a graphite fiber as a new type of solid-phase microextraction (SPME) fiber for determination of benzene series from aqueous media. The strategy for the supported OMC film preparation was combined dip-coating technology with solvent evaporation-induced self-assembly (EISA) approach. A graphite fiber was immersed in an ethanol solution containing phenolic resin and Pluronic triblock copolymer. Upon solvent evaporation and subsequent pyrolysis under 700 °C, the phenolic resin and the surfactant self-assembled on the surface of the graphite fiber to form smooth OMC film. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure with pore diameters of 4.5 nm and BET surfaces of 630 m2/g. Scanning electron microscopy (SEM) studies show the supported OMC film with thickness at 8.5 μm is continuous and defect-free. The SPME efficiency of the OMC fiber was evaluated by analysis of five benzene series (benzene, toluene, ethylbenzene, p-xylene and m-xylene) from water samples by gas chromatography-flame ionization detection (GC-FID). The analysis results indicate that the prepared OMC fiber has wide linear ranges (0.5–500 μg/L), low detection limits (0.01–0.05 μg/L) and good repeatabilities (4.0–5.8% for one fiber, 2.9–8.7% for fiber-to-fiber). Compared with commercial counterparts, the OMC fiber exhibits improved extraction efficiency for benzene series and PAHs.  相似文献   

12.
The feasibility of single-walled carbon nanotubes (SWCNTs) as adsorbents for solid-phase microextraction was investigated by using organochlorine pesticides (OCPs) as model compounds. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method has a linear range of 2-800 ng/L for most analytes, with coefficients of correlation ranging from 0.9911 to 0.9996, LODs ranged from 0.19 to 3.77 ng/L (S/N = 3), and RSDs in the range of 3.5-13.9% (n = 5). Compared with the commercial PDMS fiber, the SWCNT fiber has better thermal stability (over 350 degrees C) and longer life span (over 150 times). The developed method was applied to determine trace OCPs in lake water and wastewater samples with external standard calibration. Results showed that OCP contamination was very low in these samples, and HCHs were detected in almost all water samples while DDT concentrations were almost under detection limits in these samples. Recoveries obtained at 20 ng/L spiking level were in the range of 88.4-111% for OCPs in lake water. For wastewater samples, however, the recoveries were satisfactory for HCHs (63.6-97.1%) but relatively low for DDTs (44.7-116%) due to the high content of organic matter in wastewater.  相似文献   

13.
A new fiber for solid-phase microextraction (SPME) employing a metallic support coated with an inorganic material is proposed. A nitinol alloy (NiTi) was used as the support material due to its super elasticity and shape memory properties. Zirconium oxide (ZrO2) was electrodeposited onto NiTi using chronoamperometry. The surface characteristics and morphology of the coated and uncoated support were evaluated through scanning electronic microscopy and dispersive energy microanalysis. This assembly was applied in the extraction of three halophenols from aqueous samples. A multivariate approach was used for optimization of the variables involved in the system. The Doehlert matrix was used for evaluation of the best derivatization conditions and a Box-Behnken design to obtain the best extraction conditions. In order to investigate the repeatability, one fiber was used for six extraction tests under similar conditions and the relative standard deviations (R.S.D.) were lower than 12.5%. Detection limits were lower than 0.30 ng mL−1. Correlation coefficients were higher than 0.997. Extraction efficiency of the NiTi-ZrO2 fiber was similar to a PDMS 7 μm commercial fiber, even though it had a lower coating thickness of 1.35 μm. Considering the amount extracted per unit volume, the NiTi-ZrO2 fiber had a better extraction profile when compared to commercial fibers. The new SPME fiber has a lifetime of over 500 extractions. Thus, it is a promising alternative for low-cost analysis, as the proposed fiber is robust, and easily and inexpensively prepared.  相似文献   

14.
A novel solid-phase microextraction (SPME) fiber coated with multiwalled carbon nanotubes (MWCNTs)/Nafion was developed and applied for the extraction of polar aromatic compounds (PACs) in natural water samples. The characteristics and the application of this fiber were investigated. Electron microscope photographs indicated that the MWCNTs/Nafion coating with average thickness of 12.5 μm was homogeneous and porous. The MWCNTs/Nafion coated fiber exhibited higher extraction efficiency towards polar aromatic compounds compared to an 85 μm commercial PA fiber. SPME experimental conditions, such as fiber coating, extraction time, stirring rate, desorption temperature and desorption time, were optimized in order to improve the extraction efficiency. The calibration curves were linear from 0.01 to 10 μg mL−1 for five PACs studied except p-nitroaniline (from 0.005 to 10 μg mL−1) and m-cresol (from 0.001 to 10 μg mL−1), and detection limits were within the range of 0.03–0.57 ng mL−1. Single fiber and fiber-to-fiber reproducibility were less than 7.5 (n = 7) and 10.0% (n = 5), respectively. The recovery of the PACs spiked in natural water samples at 1 μg mL−1 ranged from 83.3 to 106.0%.  相似文献   

15.
Ma X  Li Q  Yuan D 《Talanta》2011,85(4):2212-2217
The commercial solid phase microextraction (SPME) fibers are not stable enough in organic solvent and tend to swell and strip off from the silica fiber in the high performance liquid chromatography (HPLC) mobile phase, and therefore the application of SPME coupled online with HPLC is limited. In this study, an SPME fiber coated with single walled carbon nanotubes (SWCNTs), prepared by means of electrophoretic deposition, was coupled on line to HPLC for the determination of four endocrine-disrupting compounds, i.e. bisphenol A (BPA), estrone (E1), 17α-ethynylestradiol (EE2) and octylphenol (OP), in aqueous samples. The results showed that the SWCNTs coating on the prepared fiber did not swell and strip off from the platinum fiber throughout the experiment, thus indicating a high resistance to the HPLC mobile phase, the mixture of water and acetonitrile. The SWCNTs fiber had similar (for OP) or higher (for BPA, EE2 and E1) extraction efficiencies than the commonly used polyacrylate fiber, and had a lifetime of more than 120 operation times. Under the optimized conditions, the linearity of the proposed method was 1.0-30.0 μg/L for BPA and OP and 3.0-90.0 μg/L for E1 and EE2. The limits of detection (LODs; S/N = 3) and limits of quantification (LOQs; S/N = 10) of the method were 0.32-0.52 μg/L and 1.06-1.72 μg/L, respectively. Repeatability for one fiber (n = 3) was in the range of 1.3-7.1% and fiber-to-fiber reproducibility (n = 3) was in the range of 1.6-8.4%. The proposed method was successfully applied for the analysis of spiked tap water and seawater samples with recoveries from 81.8 to 97.3%.  相似文献   

16.
通过以Nation为黏合剂、不锈钢丝为涂层载体,制备了多壁碳纳米管固相微萃取纤维.该纤维的制备方法快速、简便、成本低,并具有热稳定性好(300℃)、使用寿命长(〉100次)、对多溴联苯萃取效率高等特点.研究优化了影响萃取及分离效率的解吸温度和时间、萃取时间、搅拌速度、盐度等实验条件,进行了海水中多溴联苯的测定.对一溴联苯的线性范围为0.1-5.0ng/mL,而二溴联苯、三溴联苯、四溴联苯和五溴联苯的线性范围均为0.01~5.0ng/mL.方法的检测限为0.1~0.8ng/L.在优化的条件下分别测定了0.1和1ng/mL多溴联苯的海水加标样品,回收率在91.1%~107.3%之间,相对标准偏差小于12%.该方法分析时间短、灵敏度高、操作简便,适用于水样中多溴联苯的痕量分析.  相似文献   

17.
Fluorination of single walled carbon nanotubes was carried out at low temperature in the −191/25 °C range under 1 atm pure fluorine gas. In such conditions, the resulting C–F bonding is significantly weaker than for samples fluorinated at 280 °C. If the fluorination is performed at low temperature, fluorine atoms can be then removed from the host structure by moderated heating until 300 °C or by vacuum without strong damage on the tubes. After thermal defluorination, the resulting sample can be refluorinated similarly than the pristine tubes.  相似文献   

18.
In this study, polyaniline-co-poly(o-toluidine)/graphene oxide nanosheets composite was electrodeposited on the surface of a stainless steel wire as a new coating for headspace solid-phase microextraction of benzene, toluene, ethylbenzene and xylenes (BTEX) with gas chromatography–mass spectrometry. The characteristics of the new coating were evaluated by the scanning electron microscopy and Fourier transform infrared spectroscopy. To study the coating performance, the influence of various parameters such as deposition potential and time, concentration of the monomers and GONSs, desorption temperature and time, extraction temperature and time and ionic strength on BTEX extraction efficiency was investigated. At the optimum conditions, the linear ranges and detection limits (S/N?=?3) were found 0.01–50 and 0.001–0.05 ng mL?1, respectively. The intra-day and inter-day relative standard deviations (RSDs) at 0.5 ng mL?1 concentration level (n?=?5) using a single-fiber were from 5.4 to 8.3 and 7.5 to 10.3%, respectively. The fiber-to-fiber RSDs % (n?=?3) was between 8.4 and 12.5%. Finally, the development method was applied to the analysis of various real samples.  相似文献   

19.
Multi-walled carbon nanotubes (MWCNs) are used as adsorbent for solid-phase extraction (SPE) of several chlorophenols (CPs). CPs were adsorbed on MWCNs cartridge, then desorbed with pH 10.0 methanol, finally determined by HPLC. Under the optimized conditions, detection limits of 0.08-0.8 ng mL(-1) were obtained. The method had been applied to analyze the five CPs in tap water and river water.  相似文献   

20.
Li Q  Ding Y  Yuan D 《Talanta》2011,85(2):1148-1153
A platinum plate coated with single-walled carbon nanotubes (SWCNTs@Pt) was prepared by means of electrophoretic deposition. Using the SWCNTs@Pt plate, an electrosorption-enhanced solid-phase microextraction (EE-SPME) technique was proposed for the extraction of trace anions in water, described as follows: a positive potential was applied to the SWCNTs@Pt plate to extract F, Cl, Br, NO3 and SO42− from water using electrosorption, and then a negative potential was applied to the plate placed in ultra-pure water for the desorption of the absorbed anions, and finally the desorbed anions were analyzed using ion chromatography (IC). The EE-SPME parameters, including extraction potential and time as well as desorption potential and time, were investigated. An analytical method based on the above procedures, i.e., EE-SPME-IC, was established and used for the analysis of trace anions in water. The results showed that the application of potential on the SWCNTs@Pt plate significantly enhanced the ion extraction efficiency, and an enrichment factor of 15-38 was achieved. The SWCNTs@Pt plate could be used more than 50 times without significant decay. The linear range, the limit of detection (S/N = 3), the limit of quantification (S/N = 10) and repeatability (n = 7) of our EE-SPME-IC method were 1.0-150.0 μg/L, 0.06-0.26 μg/L, 0.19-0.85 μg/L and 2.1-8.0%, respectively. The proposed method was successfully applied for the analysis of trace anions in deionized water, and acceptable recoveries between 65.3 and 121.1% were obtained for the spiked deionized water samples.  相似文献   

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