Synthesis of carbon nanotube/layered double hydroxide nanocomposite as a novel fiber coating for the headspace solid‐phase microextraction of phenols from water samples

In this research, a carbon nanotube/layered double hydroxide nanocomposite was synthesized by an in situ growth route by electrostatic force. The prepared carbon nanotube/layered double hydroxide nanocomposite was successfully prepared and deposited on a stainless‐steel wire for the fabrication of the solid‐phase microextraction fiber. The fiber was evaluated for the extraction of phenolic compounds from water samples. Analytical merits of the method, under optimum conditions (extraction temperature: 75°C, extraction time: 30 min, desorption time: 2 min, desorption temperature 260°C, salt concentration: 10% w/v) are 0.01–300 ng/mL for the linear dynamic range and 0.005–0.08 for the limit of detection. In optimum conditions, the repeatability for one fiber (n = 3), expressed as relative standard deviation, was between 6.5 and 9.9% for the phenolic compounds.     

Hydroxyfullerene as a novel coating for solid-phase microextraction fiber with sol-gel technology

Hydroxyfullerene (fullerol) as a novel coating for solid-phase microextraction (SPME) fiber was first prepared by a sol-gel technology. The coating procedure involving sol solution composition and conditioning process was presented. A fullerene polysiloxane surface-bonded porous coating on the fused-silica fiber surface was obtained and confirmed by IR spectra and scanning electron microscopy. The coating has stable performance at high temperature (even to 360 degrees C) and solvents (organic and inorganic) because of the properties of fullerene and the chemical binding between the coating and the fiber surface. The extraction properties of the new coatings to less volatile organic compounds, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons and polar aromatic amines were investigated using headspace SPME coupled with GC-electron-capture detection and GC-flame ionization detection. In addition, compared with commercial SPME stationary phases, the new coatings showed higher sensitivity, faster velocities of mass transfer for aromatic compound, and possessed planarity molecular recognition for PCBs. Moreover, this fiber was firm, inexpensive, durable and can be prepared simply. The fiber-to-fiber reproducibility was very good.     

Highly porous silica-polyaniline nanocomposite as a novel solid-phase microextraction fiber coating

A highly porous fiber-coated SBA-15/polyaniline material was prepared for solid-phase microextraction (SPME). The SBA-15/polyaniline nanocomposite was synthesized via chemical polymerization. The prepared SBA-15/polyaniline particles were analyzed by scanning electron microscopy analysis. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). In optimum conditions (extraction temperature 60°C, extraction time 40 min, ionic strength 20%, stirring rate: 500 rpm, desorption temperature 260°C, desorption time 2 min), the repeatability for one fiber (n=3), expressed as relative standard deviation (RSD%), was between 5.3 and 8.6% for the test compounds. For deionized water, spiked with selected PAHs, the detection limits for the studied compounds were between 2 and 20 pg/mL.     

Carbon nanocones/disks as new coating for solid-phase microextraction

In this article, the potential of carbon nanocones/disks as coating for solid-phase microextraction has been evaluated for the first time. The nanostructures were immobilized on a stainless steel needle by means of an organic binder. The fiber coating obtained was ca. 50 μm of thickness and 35 mm in length. The evaluation of the sorbent capacity was carried out through the determination of toluene, ethylbenzene, xylene isomers and styrene in water samples following the headspace sampling modality (15 min, 30 °C). The fiber was then transferred to a 10 mL vial which was sealed and heated at 110 °C for 15 min in the headspace module of the instrument to achieve the thermal desorption of the analytes. Then 2.5 mL of the headspace generated were injected in the gas chromatograph-mass spectrometer for analytes separation and quantitation. The detection and quantitation limits obtained for 10 mL of sample were 0.15 and 0.5 ng mL⁻¹ (0.6 and 2 ng mL⁻¹ for toluene). The optimized procedure was applied to the determination of the selected volatile compounds in waters collected from different locations. The recovery values obtained (average recovery ca. 92%) demonstrated the usefulness of the carbon nanocones/disks as sorbent material in solid-phase microextraction.     

Periodic mesoporous organosilica with ionic liquid framework as a novel fiber coating for headspace solid-phase microextraction of polycyclic aromatic hydrocarbons

Periodic mesoporous organosilica based on alkylimidazolium ionic liquid (PMO-IL) was prepared and used as a highly porous fiber coating material for solid-phase microextraction (SPME). The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography–mass spectrometry (GC–MS). A one at-the-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, and desorption temperature and time. In optimum conditions, the repeatability for one fiber (n = 3), expressed as relative standard deviation (R.S.D.%), was between 4.3% and 9.7% for the test compounds. The detection limits for the studied compounds were between 4 and 9 pg mL⁻¹. The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis.     

Electrodeposited polyaniline as a fiber coating for solid-phase microextraction of organochlorine pesticides from water

The study on the performance of polyaniline as a fiber coating for solid-phase microextraction (SPME) purposes has been reported. Polyaniline coatings were directly electrodeposited on the surface of a stainless steel wire and applied for the extraction of some organochlorine pesticides (OCPs) from water samples. Analyses were performed using GC-electron capture detection (GC-ECD). The results obtained show that polyaniline fiber coating is suitable for the successful extraction of organochlorine compounds. This behavior is most probably due to the porous surface structure of polyaniline film, which provides large surface areas and allowed for high extraction efficiency. Experimental parameters such as adsorption and desorption conditions were studied and optimized. The optimized method has an acceptable linearity, with a concentration range of 1-5000 ng/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 12 and 17%, respectively. High environmental resistance and lower cost are among the advantages of polyaniline fibers over commercially available SPME fibers. The developed method was applied to the analysis of real water samples from Yangtse River and Tianmu Lake.     

Polypyrrole/hexagonally ordered silica nanocomposite as a novel fiber coating for solid-phase microextraction

A highly porous fiber coated polypyrrole/hexagonally ordered silica (PPy/SBA15) materials were prepared for solid-phase microextraction (SPME). The PPy/SBA15 nanocomposite was synthesized by an in situ polymerization technique. The resulting material was characterized by the scanning electron microscopy, thermogravimetric analysis and differential thermal analysis. The prepared nanomaterial was immobilized onto a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from aqueous sample solutions in combination with gas chromatography-mass spectrometry (GC-MS). A one at-the-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, desorption time and desorption temperature. In optimum conditions (extraction temperature 70°C, extraction time 20 min, ionic strength 20% (WV(-1)), stirring rate 500 rpm, desorption temperature 270°C, desorption time 5 min) the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D. %), was between 5.0% and 9.3% for the tested compounds. The quantitation limit for the studied compounds were between 13.3 and 66.6 pg mL(-1). The life span and stability of the PPy/SBA15 fiber are good, and it can be used more than 50 times at 260°C without any significant change in sorption properties. The developed method offers the advantage of being simple to use, with shorter analysis times, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis.     

Inorganic/organic mesoporous silica as a novel fiber coating of solid-phase microextraction

Mesoporous materials were employed as fast, sensitive and efficient fiber coatings of solid-phase microextraction (SPME) for the first time. Three micrometer as-synthesized C₁₆-MCM-41 particles were immobilized onto stainless steel wire with 100 μm coating thickness. In combination with high performance liquid chromatography (HPLC), extraction efficiency and selectivity of C₁₆-MCM-41 were investigated using aromatic hydrocarbons. Effect of extraction and desorption time, extraction temperature, stirring rate and ionic strength on extraction efficiency were examined. Aanalytical merits of SPME with C₁₆-MCM-41 coating were evaluated. The chromatographic peak area is proportional to the concentration of anthracene in the range 0.5-150 μg l⁻¹. The limit of detection was 0.05 μg l⁻¹ (S/N=3) and the relative standard deviation (R.S.D.) was 0.033%.     

Au nanoparticles as a novel coating for solid-phase microextraction

A novel solid-phase microextraction fiber based on a stainless steel wire coated with Au nanoparticles was prepared and has been applied, coupled with gas chromatography, to the extraction of aromatic hydrophobic organic chemical pollutants in rainwater and soil extract. The solid-phase microextraction fiber exhibited excellent extraction efficiency and selectivity. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized. Single fiber repeatability and fiber-to-fiber reproducibility were less than 7.90% and 26.40%, respectively. The calibration curves were linear in a wide range for all analytes. Correlation coefficients ranged from 0.9941 to 0.9993. The as-established SPME-GC method was used successfully to two real natural samples. Recovery of analytes spiked at 10 μg L(-1) and 100 μg L(-1) ranged from 78.4% to 119.9% and the relative standard deviations were less than 11.3%.     

Polypyrrole/graphene composite-coated fiber for the solid-phase microextraction of phenols

A polypyrrole (Ppy)/graphene (G) composite was developed and applied as a novel coating for use in solid-phase microextraction (SPME) coupled with gas chromatography (GC). The Ppy/G-coated fiber was prepared by electrochemically polymerizing pyrrole and G on a stainless-steel wire. The extraction efficiency of Ppy/G-coated fiber for five phenols was the highest compared with the fibers coated with either Ppy or Ppy/graphene oxide (GO) using the same method preparation. Significantly, compared with various commercial fibers, the extraction efficiency of Ppy/G-coated fiber is better than or comparable to 85 μm CAR/PDMS fiber (best extraction efficiency of phenol, o-cresol, and m-cresol in commercial fibers) and 85 μm polyacrylate (PA) fiber (best extraction efficiency of 2,4-dichlorophenol and p-bromophenol in commercial fibers). The effects of extraction and desorption parameters such as extraction time, stirring rate, and desorption temperature and time on the extraction/desorption efficiency were investigated and optimized. The calibration curves were linear from 10 to 1000 μg/L for o-cresol, m-cresol, p-bromophenol, and 2,4-dichlorophenol, and from 50 to 1000 μg/L for phenol. The detection limits were within the range 0.34-3.4 μg/L. The single fiber and fiber-to-fiber reproducibilities were <8.3 (n=7) and 13.3% (n=4), respectively. The recovery of the phenols spiked in natural water samples at 200 μg/L ranged from 74.1 to 103.9% and the relative standard deviations were <3.7%.     

Silicon carbide nanomaterial as a coating for solid‐phase microextraction

Silicon carbide has excellent properties, such as corrosion resistance, high strength, oxidation resistance, high temperature, and so on. Based on these properties, silicon carbide was coated on stainless‐steel wire and used as a solid‐phase microextraction coating, and polycyclic aromatic hydrocarbons were employed as model analytes. Using gas chromatography, some important factors that affect the extraction efficiency were optimized one by one, and an analytical method was established. The analytical method showed wide linear ranges (0.1–30, 0.03–30, and 0.01–30 μg/L) with satisfactory correlation coefficients (0.9922–0.9966) and low detection limits (0.003–0.03 μg/L). To investigate the practical application of the method, rainwater and cigarette ash aqueous solution were collected as real samples for extraction and detection. The results indicate that silicon carbide has excellent application in the field of solid‐phase microextraction.     

C18-MCM-41新型涂层在固相微萃取中的应用

固相微萃取（SPME）是集采样、萃取和富集于一体的样品前处理技术,该技术于1990年由Pawliszyn提出。由于其不使用有机溶剂,且简便、快速、样品用量少,因而,倍受分析工作者的青睐。     

Single layer graphitic carbon nitride-modified graphene composite as a fiber coating for solid-phase microextraction of polycyclic aromatic hydrocarbons

The authors describe a three-dimensional single layer graphitic carbon nitride-modified graphene composite (g-C₃N₄@G) deposited on a stainless steel wire by a sol-gel technique. The coated fiber was applied to direct immersion solid-phase microextraction of trace levels of polycyclic aromatic hydrocarbons (PAHs) from cosmetics samples prior to their determination by gas chromatography with mass spectrometry (GC-MS). Due to π stacking interaction and hydrophobic interaction between the g-C₃N₄@G coating and the analytes (naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene and pyrene), the fiber displays an excellent adsorption capability for the analytes. Under optimized conditions, the method has a wide linear range, low LODs (from 1.0 to 2.0 ng L⁻¹), good repeatability and high recoveries. It was successfully applied to the determination of PAHs in cosmetics. The g-C₃N₄@G fiber also exhibited good durability.

Schematic of a three-dimensional single layer graphitic carbon nitride-modified graphene composite (g-C₃N₄@G) that was coated onto a stainless steel wire for the direct-immersion solid phase microextraction of trace levels of polycyclic aromatic hydrocarbons prior to gas chromatography-mass spectrometric detection.

     

An electropolymerized aniline-based fiber coating for solid phase microextraction of phenols from water

An aniline-based polymer was electrochemically prepared and applied as a new fiber coating for solid phase microextraction (SPME) of some priority phenols from water samples. The polyaniline (PANI) film was directly electrodeposited on the platinum wire surface in sulfuric acid solution using cyclic voltammetry (CV) technique. The efficiency of new coating was investigated using a laboratory-made SPME device and gas chromatography with flame ionization detection for the extraction of some phenols from the headspace of aqueous samples. The scanning electron microscopy (SEM) images showed the homogeneity and the porous surface structure of the film. The results obtained proved the ability of this polymer as a suitable SPME fiber coating for trapping the selected phenols. Influential parameters affecting the extraction process were optimized and an extraction time of 50 min at 50 °C gave maximum efficiency, when the aqueous sample was saturated with NaCl and adjusted at pH 2. This new coating can be prepared easily in a reproducible manner and it is rather inexpensive and stable against most of organic solvents. The PANI thickness can be precisely controlled by the number of CV cycles. At the optimum conditions, the R.S.D. for a double distilled water spiked with phenol and chlorophenols at ppb level were 4.8-17% (n = 3) and detection limits for the studied compounds were between 0.69 and 3.7 ng ml⁻¹, except for phenol and 4-chlorophenol. The optimized method was successfully applied to some real-life water samples.     

Organo-modified ZnAl layered double hydroxide as new catalyst support for the ethylene polymerization

Organo-modified ZnAl layered double hydroxide was used for the first time to support a nickel a-diimine catalyst for the ethylene polymerization, and its effects on the catalytic activity, the morphology, thermal stability, and dynamic viscoelastic properties of the resultant polyethylene material were investigated. Different from the homogeneous nickel a-diimine catalyst, the supported catalyst system was found to have a long-lasting polymerization activity. Moreover, the resultant polyethylene material showed good particle morphology, improved thermal stability, as well as enhanced storage modulus and complex viscosity.     

C18 functionalized graphene oxide as a novel coating for solid-phase microextraction

A novel C18 functionalized graphene oxide (GO) coated solid-phase microextraction fiber was prepared by a novel protocol. Based on the strong van der Waals interaction present in GO and abundant oxygenous groups in GO sheets, a simple layer-by-layer self-assembly method was used in the preparation process and then C18 was successfully self-assembled on GO via C-O-Si bonding. Coupled with gas chromatography, extraction performance of the fiber was tested with polycyclic aromatic hydrocarbons (PAHs) as model analytes. The fiber not only exhibited excellent extraction efficiency and selectivity, but also showed many advantages including high rigidity, long service life and well stability toward organic solvent, acidic and alkali solutions, and high temperature. The relative standard deviations for single-fiber repeatability and fiber-to-fiber reproducibility were less than 7.26 and 17.25%, respectively. The detection limits to the PAHs were less than 0.08 μg L(-1) and the calibration curves were linear in a wide range for all analytes. The as-established Solid-phase microextraction GC method was also successfully used for determination of PAHs in two real water samples.