Silver nanoparticles supported onto a stainless steel wire for direct-immersion solid-phase microextraction of polycyclic aromatic hydrocarbons prior to their determination by GC-FID

Preparation of COF-coated nickel foam adsorbents for dispersive solid-phase extraction of 16 polycyclic aromatic hydrocarbons from Chinese herbal medicines

Covalent organic framework coated nickel foam (NF@COF) was prepared as a sorbent for the dispersive solid phase extraction (DSPE) of polycyclic aromatic hydrocarbons (PAHs) from Chinese herbal medicines (CHMs) prior to their determination by gas chromatography-mass spectrometry (GC-MS). The structure and morphology of the as-synthesized NF@COF were characterized by different techniques. Various key parameters affecting the performance of the DSPE method, including the amount of sorbent, desorption solvent, desorption volume and time, extraction time, and sample volume, were investigated. Under the optimized conditions, NF@COF combined with GC-MS was successfully applied to the determination of 16 PAHs in CHMs. The method showed wide linearity (20-2000 ng mL-1), low limits of determination (0.3-2.7 ng mL-1), and high recoveries (78.0-124%). These results revealed that NF@COF has the potential for efficient extraction of PAHs from complex samples.

Surfactant-enhanced air-agitation liquid-liquid microextraction of polycyclic aromatic hydrocarbons from edible oil using magnetic deep eutectic solvent prior to HPLC determination

Herein, an air-agitation liquid-liquid microextraction procedure was developed for the extraction of several polycyclic aromatic hydrocarbons from edible oil samples. In this study, the extraction procedure was achieved using a new magnetic deep eutectic solvent as the extraction solvent, in which there was no need for centrifugation. To enhance the rate of extraction of the analytes from the samples, the method was promoted by the use of surfactant addition. The extracted analytes were determined by high-performance liquid chromatography with a diode array detector. The influence of various parameters on the extraction efficiency was studied by response surface methodology using a central composite design. Under optimal conditions, linear calibration curves for the target analytes were achieved in the range of 0.43-250 ng g-1. The limits of detection and quantification were in the ranges of 0.04-0.13 and 0.13-0.43 ng g-1, respectively. The repeatability of the method in terms of intra- and inter-day precision was ≤4.7% and ≤6.7%, respectively. The extraction recovery of the method ranged from 75 to 88%. The obtained results show that the proposed method is efficient for the analysis of the target analytes in various oil samples without obvious matrix effects. Pyrene was found in olive oil at a concentration of 42 ng g-1.

An electrochemically fabricated ZIF-67/[HOEMIM]BF4 coating for the solid-phase microextraction and detection of polycyclic aromatic hydrocarbons

Coatings are considered to play a crucial role in solid-phase microextraction (SPME). In this work, a novel coating named ZIF-67/[HOEMIM]BF4 was fabricated through in situ potentiostatic electrodeposition in methanol solutions containing ZIF-67 precursors and 1-(2'-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HOEMIM]BF4). Compared with the traditional solvothermal method, this method reduced the synthesis time and enabled ZIF-67 to grow directly on the surface of stainless-steel wire, effectively simplifying the preparation process and improving the coating reproducibility. Owing to the inherent characteristics such as high porosity and high thermal and mechanical stability, and the impressive morphological regulation and extraction function of [HOEMIM]BF4, the developed coating exhibited a prolonged service life and a better extraction capacity for trace polycyclic aromatic hydrocarbons (PAHs) compared to single ZIF-67 and commercial fibers. Under the optimal conditions, the linear range of the ZIF-67/[HOEMIM]BF4-based SPME-GC method was 0.01-500 μg L-1, and the detection limit was 0.27-5.2 ng L-1. When applied in the determination of PAHs in a real water sample, recoveries between 85.6-117.3% were obtained, indicating the potential of ZIF-67/[HOEMIM]BF4 in the high efficiency SPME and GC analysis of PAHs.

Fabrication of a new SPME fiber based on Polyacrylic acid/ MIL-88(Fe)-NH2 composite as a self-healing coating for the analysis of breast cancer biomarkers in the urine sample

Analysis of cancer biomarkers in the body fluids is a new method for early detection of illness. However, due to the complex matrices of samples, the application of a pre-treatment method is unavoidable before the final analysis by gas chromatography (GC). Solid-phase microextraction (SPME) is a simple and, promising pre-concentration and separation method that its coatings are modified with different materials on the fibers. A new innovative self-healing polyacrylic acid PAA/MIL-88(Fe)-NH₂ composite was synthesized as an SPME coating. The parameters including pH, crosslinker, and MIL-88(Fe)-NH₂ content were optimized to formulate the composite. The prepared fiber was used to extract 2-pentanone, 2-heptanone, ethyl propionate, p-xylene, 1,2,4-trimethylbenzene, and o-cresol as a biomarker in breast cancer from urine samples. The prepared PAA/MIL-88(Fe)-NH₂ SPME fibers demonstrate excellent repeatability (relative standard deviation (RSD%)< 3.4%) and satisfactory reproducibility (RSD%<6.9%). The central composite design method was applied for the optimization of extraction parameters. Under the optimum conditions, linear dynamic ranges for biomarkers were in the acceptable range with correlation coefficients higher than 0.98. The detection limits of them were less down 0.0016 µg L^-1. Self-healing ability of fiber coating increased useful lifetime (about 120 times extraction with one fiber) as well as accuracy, reproducibility, and recovery of fibers.

Chitosan and dicationic ionic liquid intercalated clay-coated solid-phase microextraction fiber for determination of sixteen polycyclic aromatic hydrocarbons in coffee and tea samples

In the present study, solid-phase microextraction (SPME) fiber was prepared by coating clay (MMT)-chitosan (CH) and dicationic ionic liquid (DIL) onto the stainless-steel wire step by step. The characterization of fibers was performed by Fourier transform infrared spectroscopy, thermal analysis, x-ray diffraction analysis, and scanning electron microscopy. The prepared fibers were evaluated for separation and determination of 16 polycyclic aromatic hydrocarbons (PAHs) in coffee and tea samples in headspace- and direct immersion-SPME by coupling with gas chromatography/mass spectrometry. The analytical performance of MMT/CH/DIL fibers was carried out for the extraction of PAHs and compared with the performance of carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/CAR/PDMS (DVB/CAR/PDMS) fibers under optimized conditions. The wider linear ranges between 0.001 and 25 μg L^-1 with a coefficient of determination above 0.9962, low limits of detection between 0.0001 and 0.05 μg L^-1 and good intra-day repeatability from 2.45 to 6.48 % and fiber-to-fiber reproducibility from 3.19 % to 8.82 % were obtained for all PAHs in both methods with MMT/CH/octyl (O)-DIL fiber. The extraction recoveries of coffee and tea samples ranged from 87.5 to 112 % using the MMT/CH/O-DIL fiber in both SPME methods.

Fabrication of an SPME fiber based on ZnO@GA nanorods coated onto fused silica as a highly efficient absorbent for the analysis of cancer VOCs in water and urine

Analysis of volatile organic compounds (VOCs) secreted in urine, blood, breath, etc. is a new method for monitoring the metabolism and biochemistry of the human body. However, due to the complexity of samples, a pre-concentration step is necessary before the final analysis with gas chromatography-mass spectroscopy (GC-MS). Therefore, miniaturized extraction methods such as solid-phase microextraction (SPME) can be a promising and simple pre-concentration technique. Different strategies have been adopted for the fabrication or modification of SPME fibers. This study presents the preparation and characterization of glass optical fibers coated with ZnO nanorods functionalized with gallic acid (ZnO@GA nanorod) as SPME adsorbent in GC-MS. ZnO@GA nanorods were synthesized separately and then coated onto the fibers. The coated fibers were characterized by using field emission scanning electron microscopy coupled with energy dispersive analysis of X-rays (FESEM/EDAX) and Fourier transform infrared spectroscopy (FTIR) techniques. Possessing a high surface to volume ratio of ZnO nanorods and functional groups of GA, the ZnO@GA nanorod-based SPME fibers exhibited good extraction performance for VOCs comparing with the commercial polydimethylsiloxane (PDMS) coated fibers. Under optimal conditions (NaCl concentration, 30% w/v; extraction time of 25 min; pH, 5-7 and stirring rate of 400 rpm) ZnO@GA nanorods coated fibers achieved low detection limits (0.32-4.8 μg/L), low quantification limits (1.8-16.3 μg/L) and good linearity (5-1000 μg/L) for selected VOCs. The repeatability (n = 3) for a single fiber was within the range of 4.1-7.9% (intra-day) and 5.7-9.6% (inter-day) while the reproducibility (n = 3) of fiber-to-fiber were in the range of 4.7% and 9.9%. This method was successfully used for the determination of six VOCs in water and urine with satisfactory recoveries of 90-112%. ZnO@GA nanorod coated fibers, despite possessing a much thinner coating compared to the commercial fibers, revealed a better overall extraction efficiency towards VOCs. These results indicated that the ZnO@GA provided a promising alternative in sample pretreatment and analysis in GC-MS.

Triazine-based covalent organic polymer: A promising coating for solid-phase microextraction

Advancement of novel coating materials for solid-phase microextraction is highly needed for sample pretreatment. Herein, a triazine-based covalent organic polymer was constructed from the monomers of cyanuric chloride and trans-stilbene via the Friedel-Crafts reaction and thereafter used as a solid-phase microextraction fiber coating for the extraction of polycyclic aromatic hydrocarbons and their nitrated and oxygenated derivatives. The newly-developed solid-phase microextraction method coupled with gas chromatography/flame ionization detection gives enhancement factors of 548-1236 and limits of detection of 0.40-2.81 ng/L for the determination of polycyclic aromatic hydrocarbons and their derivatives. The one fiber precision for five replicate determinations of the analytes and the fiber-to-fiber precision with three parallel prepared fibers, expressed as relative standard deviations, was in the range of 4.6-9.4% and 6.2-10.9%, respectively. The relative recoveries of the analytes for environmental water samples were in the range of 88.6-106.4% with the relative standard deviations ranging from 4.0 to 11.7% (n = 5).

Poly(ionic liquid)-hybridized silica aerogel for solid-phase microextraction of polycyclic aromatic hydrocarbons prior to gas chromatography-flame ionization detection

Using poly(ionic liquid) (PIL) and tetraethyl orthosilicate (TEOS) as the co-precursors, PIL-hybridized silica aerogel was prepared via sol-gel method for solid-phase microextraction (SPME). The ratio between PIL and TEOS was regulated to achieve the best extraction effect. The aerogel was coated onto the surface of stainless steel wire to get SPME fiber. Coupled to gas chromatography-flame ionization detector (GC-FID), the fiber was separately evaluated by the determination of alkanes, polycyclic aromatic hydrocarbons (PAHs), as well as BTEX (benzene, toluene, ethylbenzene, and xylenes) in immersion mode. The extraction performance of PAHs was attributed to π stacking and hydrophobic effect. After optimization of main extraction and desorption conditions, the SPME-GC-FID method was established towards eight PAHs, and it provided low detection limits (0.005 μg L^-1, 0.010 μg L^-1) and wide linear ranges (0.016-20.00 μg L^-1, 0.033-20.00 μg L^-1) with good linear coefficients (0.9991-0.9998). The method was applied to detect trace PAHs in real water samples, with relative recoveries of 86.2-119.2%. Furthermore, PIL-hybridized silica aerogel exhibits some superiorities like higher sensitivity, shorter extraction time, and better repeatability over other extraction coatings. The present work not only extends the range of aerogel materials but also promoted their further applications in sample preparation. Graphical abstract.

Boron nitride modified reduced graphene oxide as solid-phase microextraction coating material for the extraction of seven polycyclic aromatic hydrocarbons from water and soil samples

A novel hexagonal boron nitride modified reduced graphene oxide material was synthesized and used as the adsorbent for the solid-phase microextraction of seven polycyclic aromatic hydrocarbons from water and soil samples prior to their detection by gas chromatography-flame ionization detector. Under optimal conditions, the linear response range of the analytes for water sample is 0.25-50 ng/mL with the correlation coefficients (r) ranging between 0.9953 and 0.9996. The linear range for soil sample is 1.0-400 ng/g with r ranging from 0.9959 to 0.9999. On the basis of the signal-to-noise ratio of 3, the limits of detections for the analytes ranged from 0.05 to 0.15 ng/mL for water samples, and from 0.3 to 0.5 ng/g for soil samples. The relative recoveries of the seven polycyclic aromatic hydrocarbons for water and soil samples were in the range of 79.55-120.0 and 78.76-120.8%, respectively. The relative standard deviations for the determination of the analytes in water and soil samples were lower than 11 and 10%, respectively. The method is simple and suitable for the determination of polycyclic aromatic hydrocarbon residues in water and soil samples.

Use of aloin-based and rosin-based electrospun nanofibers as natural nanosorbents for the extraction of polycyclic aromatic hydrocarbons and phenoxyacetic acid herbicides by microextraction in packed syringe method prior to GC-FID detection

The synthesis of three kinds of sorbents is described. The first kind was a hydrophobic nanofiber as a specific sorbent for non-polar compounds. The second one was a hydrophilic nanofiber as a specific sorbent for polar compounds and the third one was a generic sorbent synthesized from hydrophilic and hydrophobic compounds. The functional groups were natural compounds extracted from aloin plant and gum of pine tree. The aloin/polyacrylonitrile (PAN), rosin/PAN, and aloin/rosin/PAN electrospun nanofibers were synthesized through electrospinning strategy and then characterized using field emission scanning electron microscopy and Fourier transform infrared spectroscopy. Thereafter, the synthesized sorbents were used in microextraction using the packed syringe (MEPS) method. The determination was conducted using gas chromatography with flame ionization detection (GC-FID). Under the optimum condition, the method using aloin/rosin/PAN nanofibers as a sorbent showed a good linearity in the range 1.0-250 ng mL^-1 for polycyclic aromatic hydrocarbons (PAHs) (as a model for non-polar compounds) and 1.0-200 ng mL^-1 for phenoxyacetic acid herbicides (CAPs) (as a model for polar compounds) with correlation coefficient (R²) higher than 0.997. Limits of detections (LODs) for PAHs and CAPs were in the range 0.1-0.3 ng mL^-1 and 0.3-0.5 ng mL^-1, respectively. The intra-day (n = 3) and inter-day (between 3 days) relative standard deviations (RDSs%) were in the range 6.3-12.3% for a single syringe. Finally, the MEPS-GC-FID method was applied as a simple, facile, and time and cost-effective method to analyze environmental, farm, and industrial water samples. Graphical abstract Herein, aloin/rosin/polyacrylonitrile (PAN) electrospun nanofiber was successfully synthesized and applied as a sorbent for extraction of polycyclic aromatic hydrocarbons (PAHs) as non-polar compounds and phenoxyacetic acid herbicides (CPAs) as polar compounds from aqueous solutions before GC-FID analysis.

Rational integration of porous organic polymer and multiwall carbon nanotube for the microextraction of polycyclic aromatic hydrocarbons

By integration of benzene-constructed porous organic polymer (KBF) and multiwalled carbon nanotube (MWCNT), a MWCNT-KBF hybrid material was constructed through in situ knitting benzene with formaldehyde dimethyl acetal in the presence of MWCNTs to form a network. MWCNT-KBF was then adopted as a novel solid-phase microextraction (SPME) fiber coating. Coupled to gas chromatography-flame ionization detection, the MWCNT-KBF-assisted SPME method showed large enhancement factors (483-2066), low limits of detection (0.04-0.12 μg L^-1), good linearity (0.13-50 μg L^-1), and acceptable reproducibility (4.2-10.2%) for the determination of polycyclic aromatic hydrocarbons (PAHs). The method recoveries of seven PAHs were in the range 80.1-116.3%, with relative standard deviations (RSDs) ranging from 3.5 to 11.9%. The SPME method was successfully applied to the determination of PAHs in river, pond, rain, and waste water, providing a good alternative for monitoring trace level of PAHs in environmental water. Graphical abstract Schematic representation of the rational integration of porous organic polymer (KBF) and multiwalled carbon nanotube (MWCNT) to form a MWCNT-KBF hybrid material through in situ knitting benzene with formaldehyde dimethyl acetal at the presence of MWCNT.

Recent Applications and Newly Developed Strategies of Solid-Phase Microextraction in Contaminant Analysis: Through the Environment to Humans

The present review aims to describe the recent and most impactful applications in pollutant analysis using solid-phase microextraction (SPME) technology in environmental, food, and bio-clinical analysis. The covered papers were published in the last 5 years (2014–2019) thus providing the reader with information about the current state-of-the-art and the future potential directions of the research in pollutant monitoring using SPME. To this end, we revised the studies focused on the investigation of persistent organic pollutants (POPs), pesticides, and emerging pollutants (EPs) including personal care products (PPCPs), in different environmental, food, and bio-clinical matrices. We especially emphasized the role that SPME is having in contaminant surveys following the path that goes from the environment to humans passing through the food web. Besides, this review covers the last technological developments encompassing the use of novel extraction coatings (e.g., metal-organic frameworks, covalent organic frameworks, PDMS-overcoated fiber), geometries (e.g., Arrow-SPME, multiple monolithic fiber-SPME), approaches (e.g., vacuum and cold fiber SPME), and on-site devices. The applications of SPME hyphenated with ambient mass spectrometry have also been described.

Electroless deposition of silver nanofractals on copper wire by galvanic displacement as a simple technique for preparation of porous solid-phase microextraction fibers

A novel and porous solid-phase microextraction fiber was prepared by quick and simple galvanic displacement reaction and applied to the determination of some polycyclic aromatic hydrocarbons in sunflower oil. The parameters affecting the porosity and thickness of the fiber, and parameters affecting the extraction efficiency, including the extraction time, temperature, and ionic strength, were investigated and optimized. The morphology of prepared fiber was characterized by optical and scanning electron microscopy and thermal and chemical stabilities of the fiber were studied. Under the optimum conditions, the limits of detection ranged between 0.1 ng/mL for pyrene to 1.2 ng/mL for anthracene, and LOQ ranged between 0.3 ng/mL for pyrene to 3.6 ng/mL for anthracene. The relative standard deviations, including repeatability (within fibers) and reproducibility (between fibers), varied between 3.2-8.9 and 5.6-9.8%, respectively.

Magnetic fiber headspace solid-phase microextraction coupled to GC-MS for the extraction and quantitation of polycyclic aromatic hydrocarbons

A technique was developed for magnetic fiber headspace-solid phase microextraction (MF-HS-SPME) of polycyclic aromatic hydrocarbons (PAHs). The efficiency of the extraction of a steel SPME fiber coated with an aminoethyl-functionalized SBA-15 (Santa Barbara Amorphous 15; a nanoporous sorbent) is substantially improved after its magnetization during HS-SPME. The effects of magnetic field strength, extraction temperature, extraction time, moisture content of the sample, desorption time and desorption temperature were optimized using a simplex method. The application of a moderately strong magnetic field to the fiber results in up to 135% increase in the extraction efficiency and wider linear dynamic ranges. The PAHs (specifically naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene and pyrene) were then quantified by GC-MS analysis. Comparison of an electromagnet and a permanent magnet indicated the superior effect of the permanent magnet for the target analytes due to the Ohmic heating of the magnetic coil and its negative effect on the extraction of some of the PAHs. The limits of detections of the PAHs are between 0.17 to 0.57 ng g^-1 by using the electromagnet, and between 0.10 and 0.32 ng g^-1 for the permanent magnet. Relative standard deviations of 2.9 to 7.6% were obtained for six replicated analyses of the analytes. The method was applied to some polluted soil samples, and satisfactory results were obtained. Graphical abstract Schematic representation of the designed magnetic fiber headspace solid-phase microextraction (MF-HS-SPME) system using (a) an electromagnet, (b) a pair of permanent disc magnets.

Nanoparticles Used for Extraction of Polycyclic Aromatic Hydrocarbons

This article offers a review on the application of nanoparticles (NPs) that have been used as sorbents in the analysis of polycyclic aromatic hydrocarbons (PAHs). The novel advances in the application of carbon NPs, mesoporous silica NPs, metal, metal oxides, and magnetic and magnetised NPs in the extraction of PAHs from matrix solutions were discussed. The extraction techniques used to isolate PAHs have been highlighted including their advantages and limitations. Methods for preparing NPs and optimized conditions of NPs extraction efficiency have been overviewed since proper extraction procedures were necessary to achieve optimum analytical results. The aim was to provide an overview of current knowledge and information in order to assess the need for further exploration that can lead to an efficient and optimum analysis of PAHs.

Polydopamine-assisted attachment of β-cyclodextrin onto iron oxide/silica core-shell nanoparticles for magnetic dispersive solid phase extraction of aromatic molecules from environmental water samples

Pollution monitoring in a contaminated environmental water samples is a big challenge. In this article, immobilization of β-cyclodextrin molecules onto the magnetic core-shell silica nanoparticles was conducted by using adhesive properties of polydopamine. The synthesis path was included of three steps: producing Fe₃O₄ nanoparticles as a core, coating the cores with a silica layer, and further coating with β-cyclodextrin molecules. The structural characteristics of the synthesized nanocomposite were investigated by using attenuated total reflection-Fourier transform infrared spectroscopy, x-ray diffraction analysis, field emission scanning microscopy, transmission electron microscopy, dynamic light scattering, vibrating-sample magnetometer and energy-dispersive X-ray spectroscopy. Afterwards, obtained nanocomposite was used to extract eight polycyclic aromatic hydrocarbons from environmental water samples. Results were demonstrated that analyts with different chemical structures had different extraction manners during the process. Important effective parameters on the extraction efficiency; such as sorbent type and mass, desorption solvent (type and volume), salt concentration and the time of extraction & desorption; were investigated. Under the optimum operating conditions, good linearity within the range of 1-1000 ng/mL was obtained while coefficient of determination (r²) was in the range of 0.990-0.998. The limits of detection were between 0.04 and 0.57 ng/mL, and the enrichment factor was found to be 21-90. This nanocomposite was also applied for the extraction and enrichment of aromatic analytes from the canal and rain water samples prior to gas chromatography analysis.

Braid solid-phase microextraction of polycyclic aromatic hydrocarbons by using fibers coated with silver-based nanomaterials in combination with HPLC with fluorometric detection

Authors propose a novel braid support configuration for use in solid-phase microextraction (SPME) fibers. Two different braided supports (double and triple) were prepared and compared with the conventional single support configuration. Three kinds of silver-based nanomaterials that serve as coatings on these supports are described. They included silver dendrites, silver nanoparticles (AgNPs), and silver dendrites decorated with AgNPs (Ag-dendrites@AgNPs). They were prepared by electrodeposition, a layer-by-layer (LBL) method, and a hybrid strategy, respectively. Fibers were used in the direct-immersion (DI) mode of SPME. Five polycyclic aromatic hydrocarbons (PAHs) were studied as model analytes by DI-SPME when analyzing (spiked) underground waters. PAHs were further determined with high-performance liquid chromatography (HPLC) and fluorescence detection. The analytical performance of the fibers was compared to that of the commercial polydimethylsiloxane (PDMS) fiber of 100 μm thickness. AgNPs obtained by LBL was the best coating and the double braid was the best support configuration. The configuration of the SPME support always played an important role independently on the coating material, being always beneficial the use of double-braids. Despite the low coatings volumes of the silver-based fibers compared to that of PDMS, the analytical features of the method were adequate. Figures of merit include: (a) limits of detection down to 20 ng·L^-1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) of <13%, <12%, and < 13%, respectively; and (c) adequate operational lifetime (>60 extractions). Graphical abstract Schematic presentation of braided solid-phase microextraction support configurations together with different silver-based nanomaterials as coatings.

Solid phase microextraction of polycyclic aromatic hydrocarbons by using an etched stainless-steel fiber coated with a covalent organic framework

A new covalent organic framework (COF) was synthesized by the amide coupling between 1,3,5-tris(4-aminophenyl)benzene and trimesoyl chloride at room temperature. The COF was applied as a steel fiber coating for the solid phase microextraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The effect of extraction time, salt concentration, and extraction temperature on the efficiency of SPME was optimized by a Box-Behnken design. The PAHs were quantified by gas chromatography with mass spectrometric detection. Figures of merit include (a) a wide linear range (typically from 0.2 ng L^-1 to 2 μg L^-1), (b) low limits of detection (0.29 to 0.94 ng L^-1 at S/N = 3), and (c) high enrichment factors (EFs; 819-2420). Density functional theory was employed to study the interaction between the COF cluster and the PAHs. The results demonstrated that the EFs increase with the enhancement of π stacking interaction. The repeatability (one fiber; n = 5) and reproducibility (fiber to fiber; n = 5), expressed as the relative standard deviations were in the range of 4.3%-8.4% and 8.5-11.0%, respectively. The recoveries of the PAHs from water samples spiked at levels of 20.0 and 100 ng L^-1 ranged from 79.0% to 105.0%. Graphical abstract A covalent organic framework prepared from 1,3,5-tris(4-aminophenyl)benzene and trimesoyl chloride (TAPB-TMC-COF) was synthesized and employed as solid phase microextraction (SPME) fiber coating for the extraction of polycyclic aromatic hydrocarbons from water samples prior to gas chromatography (GC) - mass spectrometric (MS) detection.

Micro-solid phase extraction of some polycyclic aromatic hydrocarbons from environmental water samples using magnetic β-cyclodextrin-carbon nano-tube composite as a sorbent

Previous studies have demonstrated the excellent capability of the cyclodextrins in pre-concentration of the organic pollutants from the aqueous solutions. In this work, β-cyclodextrin- multiwalled carbon nano-tube composite was produced from the reaction of oxidized carbon nano-tube with cyclodextrin in the presence of the hydrazine hydrate, and subsequently attaching this composite to the iron oxide nano-particles. Prepared magnetic nano-composite was characterized by the attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), the thermogravimetric analysis (TGA), the field emission scanning electron microscopy (FESEM), and the X-ray diffraction (XRD). This composite was applied to extract seven polycyclic aromatic hydrocarbons (PAHs) from the environmental water samples as follows: naphthalene, acenaphthene, fluorene, phenanthrene, fluoranthene, pyrene and benzo[a]pyrene. Analytes analysis was performed using the gas chromatography (GC) followed by the flame ionization detection (FID), and the predominant parameters influencing the extraction efficiency were investigated thoroughly. Under the optimized extraction conditions, the enrichment factor (EF) was ranging from 41.3 to 49.3 (EF_max = 50.0), and a suitable linearity was obtained (R² = 0.992-0.997) within the range of 2.0-1000 ng/mL. The limits of the quantification and detection were 2.0-10.0 and 0.6-3.0 ng/mL, respectively. Finally, the synthesized magnetic sorbent and method were successfully utilized for the analysis of rain, well and agricultural water samples. The relative recoveries were ranging from 75.3-107.0% with an acceptable precision (5.5-8.3%) for PAHs extraction.