Solid-phase microextraction of 2,4,6-trinitrotoluene using a molecularly imprinted-based fiber

A molecularly imprinted polymer with trinitrotoluene as the template molecule was synthesized and used as the novel coating for solid-phase microextraction of the nitroaromatic explosive 2,4,6-trinitrotoluene for its selective determination. The fiber was characterized in terms of coating thickness, morphology, intra- and inter-batch repeatability and extraction efficiency. An average thickness of 50 ± 4 μm with a uniform distribution of the coating was obtained. Good performances of the developed procedure in term of both intra-batch and inter-batch repeatability with relative standard deviations <8% were obtained. Finally, detection and quantitation limits in the low nanogram per kilogram levels were achieved proving the superior extraction capability of the developed coating, obtaining gas chromatography-mass spectrometry responses about two times higher than those achieved using commercial devices.     

Solid-phase microextraction of monocyclic aromatic amines using novel fibers coated with crown ether.

Three solid-phase microextraction (SPME) fibers prepared by the sol-gel method, containing hydroxydibenzo-14-crown-4 (OH-DB14C4), dihydroxy-substituted saturated urushiol crown ether (DHSU14C4) and 3,5-dibutyl-unsymmetry-dibenzo-14-crown-4-dihydroxy crown ether (DBUD14C4), respectively, were evaluated for the determination of aromatic amine (aniline, m-toluidine, N,N-diethylaniline, N-ethyl-m-toluidine, 3,4-dimethylaniline). The sol-gel-derived hydroxy-dibenzo14-crown-4-coated fiber has the best affinity for several aniline derivatives. Optimization was carried out for the determination of aromatic amines with SPME fibers. The linearity was from 0.11 to 29 microg/ml and detection limits varied from 0.17 to 0.98 ng/ml. Relative standard deviation (n=5) was found to be 3.23-6.20%. The coating proved to be very stable at high temperature (to 340 degrees C) and in different solvents (organic and inorganic). The method was applied to the determination of aromatic amines in wastewater samples from a pharmaceutical factory.     

Solid phase microextraction using fused silica fibers coated with graphitized carbon black

Summary This paper presents the results obtained using fused-silica fibers coated with graphitized carbon black (Carbograph-Alltech) for solid-phase microextraction (SPME). The extraction and calibration curves relative to organic micro-pollutants present in gaseous and aqueous samples are reported. Examples of applications of this extraction procedure to GC and GC-MS analysis of organic micro-pollutants in actual samples are also reported.     

Microextraction of phenolic compounds using a fiber coated with a polyaniline-montmorillonite nanocomposite

Microchimica Acta - A highly porous fiber coated polyaniline/montmorillonite clay was prepared for solid-phase microextraction. The nanocomposite was synthesized by in-situ polymerization. The...     

Solventless determination of caffeine in beverages using solid-phase microextraction with fused-silica fibers.

Caffeine concentrations in beverages were determined using a simple and rapid method based on microextraction of caffeine onto the surface of a fused-silica fiber. The uncoated fiber was dipped into the beverage sample for 5 min after the addition of isotopically labeled (trimethyl 13C)caffeine. The adsorbed caffeine was then thermally desorbed in a conventional split/splitless injection port, and the concentration of caffeine was determined using gas chromatography with mass spectrometric detection. Quantitative reproducibilities were ca. 5% (relative standard deviation) and the entire scheme including sample preparation and gas chromatographic analysis was completed in ca. 15 min per sample. The potential of the microextraction technique for the analysis of flavor and fragrance compounds in non-caffeinated beverages is also demonstrated. Since no solvents or class-fractionation steps are required, the method has good potential for automation.     

Solid-phase microextraction and chromatography of water samples containing aromatic compounds

A concentrator was designed for solid-phase microextraction of aromatic compounds (benzene, toluene, ethylbenzene, o-xylene) from water samples. The concentrator was used as an attachment to a water vapor mobile phase chromatograph with a detection limit (compounds <1 μg/l).     

Solid-phase microextraction using octadecyl-bonded silica immobilized on the surface of a rotating disk: Determination of hexachlorobenzene in water

Solid-phase microextraction of hexachlorobenzene from water was implemented for the first time on a rotating disk coated with an octadecyl-bonded silica (C₁₈) sorptive phase. The results indicate that the sorption performance of this phase for the model analyte selected is similar to that observed using a rotating disk containing PDMS. In both cases, equilibrium is achieved within approximately 120 min for samples volumes of 50 mL and decreases to 20–30 min when the sample volume is decreased to 10 mL. The comparable behavior observed for the sorption of HCB in both phases is consistent with a similar rate-determining step for extraction, which suggests that the overall mass transfer of analyte is not limited by internal diffusion into the phase but by diffusion into the aqueous stagnant layer. The main advantage in the use of the C₁₈ phase is that the elution of the analyte was achieved in 15 min compared with 45 min for PDMS because, in the case of C₁₈, dichloromethane can be used as the eluting solvent.     

Determination of polycyclic aromatic hydrocarbons by solid-phase microextraction coupled to HPLC using a fiber with mesoporous silica coating

A novel SPME-HPLC method was developed for the determination of trace amounts of polycyclic aromatic hydrocarbons (PAHs). It was found that the SPME device with C₈H₁₇-SBA-15 (C ₈-SBA-15) mesoporous silica coating had high extraction efficiency, sufficient chemical and hydrothermal stability and good reversibility. The determination conditions for environmental pollutants like PAHs including extraction and desorption time, extraction temperature, ionic strength and stirring rate were optimized. Under optimized experimental conditions, results with good accuracy (with a recovery of 97.5–101.7%), precision (with a standard deviation of 0.15–1.07%) and low detection limit (LOD, 0.05–0.25 μg/L) were obtained, suggesting the SPME devices using chemical modified SBA-15 as coating material are promising in preconcentration, separation and determination of interested analytes in the future.     

Solid-phase microextraction using a diglycidyloxycalix[4]arene coated fiber combined with gas chromatography: very simple, rapid and sensitive method for the determination of chlorobenzenes in water

A fiber material for solid-phase microextraction (SPME) was obtained by blending 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-diglycidyloxycalix[4]arene with hydroxy-terminated silicone oil by sol-gel technology. It was used for headspace SPME combined with gas chromatography using electron capture detection to determine seven chlorobenzenes in water matrix. Optimum extraction conditions were 15 min at 20 °C with a solution containing 300 g L^?1 sodium chloride. The fiber exhibits far higher extraction efficiency than the commercially available poly(dimethylsiloxane) (PDMS) and PDMS-divinylbenzene fibers. The detection limits range from 0.32 to 2.25 ng L^?1, and the relative standard deviations are <5%. The calibration curves display a high level of linearity, with correlation coefficients ranging between 0.9996 and 1. The method was applied to analyze a lake water sample that was found to be polluted with 1,2,3,4-tetrachlorobenzene and hexachlorobenzene. It was compared to the United States Environmental Protection Agency method and other recently introduced methods. The results demonstrate that the technique is rapid, simple, and sensitive, and thus represents an attractive alternative for ultra-trace analysis of chlorobenzenes in water samples.     

Solid-phase microextraction with on-fibre derivatisation applied to the analysis of volatile carbonyl compounds

We have used a fast, sensitive and efficient method for the analysis of volatile carbonyl compounds (saturated aliphatic and unsaturated aldehydes) based on solid-phase microextraction with on-fibre derivatisation. Pentafluorophenylhydrazine was absorbed onto a poly(dimethylsiloxane)/divinylbenzene-coated fibre and exposed to the vapours of aldehyde-containing matrices. The hydrazones formed on the fibre were desorbed into the gas chromatograph injection port and quantified by means of electron-capture detection with high sensitivity (10-90 fmol) and good reproducibility (RSD<10%). The method was applied to the headspace-sampling of volatile carbonyl compounds released during the thermally-induced degradation of sunflower oil.     

聚醚砜酮涂层纤维顶空固相微萃取-气相色谱法分析水中痕量的酚类化合物

应用自制的聚醚砜酮(PPESK,30 μm)涂层纤维,采用顶空固相微萃取-气相色谱法测定水中痕量的酚类化合物。优化了固相微萃取温度、萃取时间、pH值和离子强度。方法的检出限为0.003～0.041 μg/L,相对标准偏差低于16%(n=5)。将PPESK涂层纤维与商品化的聚丙烯酸酯涂层纤维对比,结果表明PPESK萃取酚类化合物有较高的萃取富集倍数。用所制备的PPESK萃取头分析自来水、海水等实际水样,20 μg/L添加水平下的回收率分别为100.5%～111.8%和94.8%～117.3%。     

A silica fiber coated with a ZnO-graphene oxide nanocomposite with high specific surface for use in solid phase microextraction of the antiepileptic drugs diazepam and oxazepam

A novel ZnO-graphene oxide nanocomposite was prepared and is shown to be a viable coating on fused silica fibers for use in solid phase microextraction (SPME) of diazepam and oxazepam from urine, this followed by thermal desorption and gas chromatographic quantitation using a flame ionization detector. A central composite design was used to optimize extraction time, salt percentage, sample pH and desorption time. Limits of detection are 0.5 μg·L^?1 for diazepam and 1.0 μg·L^?1 for oxazepam. Repeatability and reproducibility for one fiber (n?=?4), expressed as the relative standard deviation at a concentration of 50 μg·L^?1, are 8.3 and 11.3% for diazepam, and 6.7 and 10.1% for oxazepam. The fiber-to-fiber reproducibility is <17.6%. The calibration plots are linear in the 5.0–1000 μg·L^?1 diazepam concentration range, and from 1.0–1000 μg·L^?1 in case of oxazepam. The fiber for SPME has high chemical and thermal stability (even at 280 °C) after 50 extractions, and does not suffer from a reduction in the sorption capacity.

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Graphical abstract A hydrothermal method was introduced for preparation of ZnO- GO nano composite on a fused silica fiber as solid phase microextraction with high mechanical, chemical stability and long service life

     

Preparation of metal wire supported solid-phase microextraction fiber coated with multi-walled carbon nanotubes

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%.     

固相微萃取涂层的制备及其在水体和气态基质中的应用

采用物理涂渍的方法制备了γ-Al2O3固相微萃取涂层。通过γ-Al2O3固相微萃取（SPME）-气相色谱（GC）联用技术,对水中痕量苯系物苯、甲苯、乙苯、二甲苯异构体(BTEXs)进行萃取分析,结果表明该涂层具有热稳定性强(最高使用温度可达350 ℃)、灵敏度高(检测限为1~10 μg/L)以及制备重复性好（相对标准偏差为8.3%）的特点;同时该涂层对气态基质中的污染物亦可进行萃取分析。     

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%.     

Solid-phase microextraction coupled with capillary electrophoresis to determine ephedrine derivatives in water and urine using a sol-gel derived butyl methacrylate/silicone fiber

A sensitive method for determination of ephedrine derivatives using headspace solid-phase microextraction (SPME) with a novel fiber followed by capillary electrophoresis has been developed. The co-poly(butyl methacrylate/hydroxy-terminated silicone oil) (BMA/OH-TSO) was used as stationary phases with the aid of γ-methacryloxypropyltrimethoxysilane (KH-570) as bridge in SPME using sol-gel-coating method and cross-linking technology. It has high extraction efficiency for ephedrine derivatives in comparison with commercial poly(dimethylsiloxane) and poly(acrylate)-coated fiber. The coating exhibits good thermal and solvent stability as well as long lifetime. A simple and flexible device for desorption of analytes after headspace SPME was constructed. The effect of various experimental parameters for SPME (temperature, time, pH, ionic strength, desorption solvent, etc.) were discussed. Field amplified sample injection (FASI) was applied for on-line sample concentration and a sensitivity enhancement of two orders of magnitude was achieved. Linear ranges were found to be 20-5000 ng/ml. The detection limits for (1R,2S)-ephedrine, (1R,2R)-pseudoephedrine and (1S,2S)-pseudoephedrine were 3, 5 and 5 ng/ml, respectively. Relative standard deviation (n = 6) was found to be 4.96-7.57%. The method was successfully applied to the analysis of ephedrine derivatives in human urine.     

Solid-phase microextraction coupled with capillary electrophoresis for the determination of propranolol enantiomers in urine using a sol-gel derived calix[4]arene fiber

A new type of diglycidyloxy-calix[4]arene coated fiber made by sol-gel method was initially prepared for capillary electrophoresis (CE) sample pretreatment. By using headspace solid-phase microextraction (SPME) combined with a novel back-extraction facility coupled off-line to capillary zone electrophoresis (CZE), the simultaneous determination of propranolol enantiomers in human urine was achieved. The clean up effect and preconcentration effect were realized for the first time without derivatization during the SPME process in terms of these strong polarity and thermal stable compounds. Ultrasonic back-extraction and field amplified sample injection (FASI) technologies were employed. Extraction and back-extraction parameters were optimized. Preconcentration of the sample by calix[4]arene fiber based SPME and FASI increased the sensitivity, yielding a limit of detection (LOD) of 0.01microg/ml by CZE-diode array detection (DAD). Method repeatability (RSD<6.5%) and fiber reusability (>150 extraction procedures) were observed over a linear range (0.05-10microg/ml) in urine samples. Based on the superior thermal stability, high alkali- and solvent-resistant ability, marvelous repeatability and long lifetime of the novel fiber, this SPME-FASI-CZE procedure could meet the demand of minimum required performance limit (MRPL) set by the World Anti-doping Agency (WADA) for the detection of propranolol in urine samples.     

High extraction efficiency fiber coated with calix[4] open-chain crown ether for solid-phase microextraction of polar aromatic and aliphatic compounds

The calix[4] open-chain crown ether, 5,11,17,23-tetra-tert-butyl-25,27-di(2-allyloxyethoxyl)-26,28-dihydroxycalix[4]arene was synthesized and used for preparation of solid-phase microextraction (SPME) fibers of enhanced extraction efficiency. The new SPME coating made from calix[4] open-chain crown ether and hydroxyl-terminated silicone oil was developed with the aid of vinyltriethoxylsilane as bridge using sol-gel method and cross-linking technology. The efficiency of the novel fiber in the extraction of polar aromatic and aliphatic compounds, such as phenols, alcohols, and volatile fatty acids, was also investigated. Due to the introduction of the polar open-chain crown ether in calix[4]arene molecules, the calix[4] open-chain crown ether fiber showed much better selectivity and sensitivity to these polar compounds in comparison with calix[4]arene fiber. It also had superior extraction efficiency when compared to commercial poly(dimethylsiloxane)-divinylbenzene and polyacrylate fibers. Parts per billion to parts per trillion level detection limits were achieved for most of the analytes through SPME in conjunction with GC and flame ionization detector. The linear ranges were two to four orders of magnitude, and the RSD values were below 7% for all analytes. The novel fiber was applied to determine volatile alcohols and fatty acids in wine samples. The volatile-free wine prepared in this work was used to assure similar chemical environment for analytes in both calibration solutions and in real wine samples, thus compensating for possible matrix interferences. The established internal standard method using 4-methyl-2-pentanol as internal standard showed satisfactory accuracy and precision.     

Solid-phase microextraction of sulfonylurea herbicides by using borate-reinforced multiple monolithic fibers

Microchimica Acta - The authors describe a highly sensitive method for the aptamer (Apt) based impedimetric determination of cocaine. The surface of a screen-printed electrode (SPE) was modified...