Microextraction Device Research Articles

Selective liquid phase micro-extraction of metal chloro-complexes from saline waters using ionic liquids

Existing methods for the extraction of priority metallic pollutants as Ag, Cd, Cu, Ni and Zn from saline waters present limited efficacy due to the high complexity of the water matrix, which affects metals speciation. There is a lack of reagents for the efficient extraction of the metal chlorocomplexes formed at the natural pH of saline waters, requiring tedious and reagent consuming processes. To develop a simple method for the efficient micro-extraction of metallic chlorocomplexes in saline waters, two task specific ionic liquids (TSILs) are proposed. The TSILs methyltrioctilammonium hexylsulfanyl acetate ([N1888][C6SAc]) and methyltrioctilphosphonium hexylsulfanyl acetate ([P1888][C6SAc]) have been supported on a solvent bar micro-extraction (SBME) device and applied to the micro-extraction of Ag, Cd, Cu, Ni and Zn from seawater, as well as inland and marshland salt-pan waters. The extraction efficacy was related with the formation of negatively charged chlorocomplexes, being higher for Cd, Ag and Zn than for Cu and Ni. Concluding, the proposed methodology can be considered as a valuable and simple tool for the selective extraction of metals from saline and hypersaline natural waters.

Decoration of Fe3O4@SiO2@ZnO as a high performance nanosorbent on a stir bar microextraction device for preconcentration and determination of cadmium in real water samples

In this work, a novel, fast and simple method that so called stir bar sorptive–dispersive microextraction (SBSDµE) applied for preconcentration and determination of trace amounts of Cd (II) ions in real water samples. For this purpose, Fe3O4@SiO2@ZnO core–shell microspheres were coated on a neodymium stir bar magnetically, and dispersed in the sample solution at high stirring rate, while adsorbing Cadmium target ions. The effective factors on extraction of Cd (II) (pH, stirring rate, salt effect and extraction time) were investigated and optimized using response surface methodology (RSM) as a powerful statistical technique. Under the optimal conditions, linear dynamic range (LDR) of SBSDµE method was 1–150 ng mL−1, the intra-day and inter-day relative standard deviations (RSD%) at 80 ng mL−1 concentration level were 3.7% and 8.4% (n = 5), respectively. The limit of detection (LOD) was 0.37 ng mL−1 and the limit of quantification (LOQ) was 1.23 ng mL−1. The proposed microextraction analytical method was successfully used for determination of ultra trace amounts of cadmium in some real water samples.

Ballpoint tip-protected oil-in-salt liquid-phase microextraction with high performance liquid chromatography for the determination of magnolol and honokiol from cortex Magnoliae officinalis

A ballpoint tip-protected oil-in-salt liquid-phase microextraction protocol coupled with high performance liquid chromatography with ultraviolet detection is reported for the preconcentration and determination of trace magnolol and honokiol in cortex Mangnolia officinalis. A stainless steel ballpoint tip filled with n-hexanol in cavity was immersed in sodium chloride solution to form oil-in-salt double membranes in its open tail which was used as the microextraction device. The experimental variables affecting the performance, such as the extraction solvent, sample pH, extraction time, agitation speed, salting-out location, salt concentration, and immersion time in the sodium chloride solution, were optimized in detail. Under the optimized conditions, the enrichment factors for honokiol and magnolol were 73 and 76, and the extraction efficiencies were 23.4% and 24.3%, respectively. The linear ranges were from 0.004 to 4 μg mL−1 for honokiol and 0.006 to 6 μg mL−1 for magnolol with coefficients of determination (R2) exceeding 0.9940 for both analytes. Detection limits from 0.4 to 0.6 ng mL−1 and quantification limits from 0.8 to 1.2 ng mL−1 were obtained, respectively. Satisfactory precision (4.4% to 9.7%) and accuracy (84.5% to 99.8%) were obtained. In addition, the enrichment factors and extraction efficiencies of the analytes were determined. The proposed procedure, compared with ballpoint tip-protected liquid-phase microextraction or other microextraction protocols, is simple, convenient and efficient for concentrating and enriching trace magnolol and honokiol in complex matrix.

Direct capillary electrophoresis analysis of basic and acidic drugs from microliter volume of human body fluids after liquid-phase microextraction through nano-fibrous membrane.

In the present work, a disposable microextraction device with a polyamide 6 nano-fibrous supported liquid membrane (SLM) is employed for the pretreatment of minute volumes of biological fluids. The device is placed in a sample vial for an at-line coupling to a commercial capillary electrophoresis instrument with UV-Vis detection (CE-UV) and injections are performed fully automatically from the free acceptor solution above the SLM with no contact between the capillary and the membrane. Up to 4-fold enrichment of model basic (nortriptyline, haloperidol, loperamide, and papaverine) and acidic (ibuprofen, naproxen, ketoprofen, and diclofenac) drugs is achieved by optimizing the ratio of the donor to the acceptor solution volumes (16 to 4 μL, respectively). The actual setup enables SLM extractions from less than a drop of sample and is suitable for pretreatment of scarce human body fluids. Two unique methods are reported for efficient clean-up and enrichment of the basic and acidic drugs from capillary blood (formed as dried blood spot), serum, and urine samples, which enable their determination at therapeutic and/or toxic levels. The hyphenation of the SLM extraction with CE-UV analysis provides good repeatability (RSD, 2.4-14.9%), linearity (r2, 0.988-1.000), sensitivity (LOD, 0.017-0.22 mg L-1), and extraction recovery (ER, 20-106%) at short extraction times (10 min) and with minimum consumption of samples and reagents. Graphical abstract.

Hybrid monoliths with metal-organic frameworks in spin columns for extraction of non-steroidal drugs prior to their quantitation by reversed-phase HPLC.

A (glycidyl methacrylate)-co-(ethylene glycol dimethacrylate) polymer (poly(GMA-co-EDMA)) was functionalized with metal-organic frameworks (MOF) and used as a sorbent for solid-phase extraction (SPE). The polymeric sorbent was prepared in-situ by photopolymerization in a previously wall-modified spin column, and then modified with an amino-modified MOF of type NH2-MIL-101(Cr). The sorbents were used for the extraction of nonsteroidal anti-inflammatory drugs (NSAIDs) from human urine samples. The sorbent was compared with the parent monolith and embedded approach, where the MOF particles are admixed in the polymerization mixture before the in-situ polymerization in the modified spin column. SPE is performed by percolating the sample solutions in a centrifuge, which streamlines the SPE steps. The hybrid composites were characterized by scanning electron microscopy and nitrogen intrusion porosimetry. Three NSAIDs (ketoprofen, flurbiprofen, and ibuprofen) were tested. They were eluted from the sorbent with acidified water-acetonitrile mixtures and subsequently analyzed by reversed-phase HPLC with UV detection. The detection limits varied in the range from 0.1 to 7μg·L-1, and the precisions (relative standard deviation) were <14% in all the cases. The recoveries were between 71.0 and 78.0% in spiked urine samples. Graphical abstractA hybrid monolith modified with amino-modified MOF [named NH2-MIL-101(Cr)] in wall-modified spin columns was prepared. The resulting micro-extraction device was applied to the extraction and preconcentration of non-steroidal anti-inflammatory drugs.

Metal–Organic Frameworks as Key Materials for Solid-Phase Microextraction Devices—A Review

Metal–organic frameworks (MOFs) have attracted recently considerable attention in analytical sample preparation, particularly when used as novel sorbent materials in solid-phase microextraction (SPME). MOFs are highly ordered porous crystalline structures, full of cavities. They are formed by inorganic centers (metal ion atoms or metal clusters) and organic linkers connected by covalent coordination bonds. Depending on the ratio of such precursors and the synthetic conditions, the characteristics of the resulting MOF vary significantly, thus drifting into a countless number of interesting materials with unique properties. Among astonishing features of MOFs, their high chemical and thermal stability, easy tuneability, simple synthesis, and impressive surface area (which is the highest known), are the most attractive characteristics that makes them outstanding materials in SPME. This review offers an overview on the current state of the use of MOFs in different SPME configurations, in all cases covering extraction devices coated with (or incorporating) MOFs, with particular emphases in their preparation.

Determination of Hydrophilic UV Filters in Real Matrices Using New-Generation Bar Adsorptive Microextraction Devices

In the present contribution, new-generation bar adsorptive microextraction devices combined with microliquid desorption, followed by high-performance liquid chromatography–diode array detection (BAµE-µLD/HPLC–DAD) are proposed for the determination of two very polar ultraviolet (UV) filters (2-phenylbenzimidazole-5-sulfonic acid (PBS) and 5-benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid (BZ4)) in aqueous media. Different sorbents were evaluated as BAµE coating phases, in which polystyrene–divinylbenzene polymer showed the best selectivity for the analysis of both UV filters, with average extraction efficiency of 61.8 ± 9.1% for PBS and 69.5 ± 4.8% for BZ4. The validated method showed great reproducibility for the analysis of PBS and BZ4 UV filters, providing suitable limits of detection (0.04 µg L−1 and 0.20 µg L−1), as well as good linear dynamic ranges (0.16–16.0 and 0.8–80.0 µg L−1), respectively. The proposed methodology was applied for monitoring the target analytes in several real matrices, including tap, sea, and estuarine waters, as well as wastewater samples. Despite some matrix effects being observed for some real samples, good selectivity and linearity were obtained. The present contribution showed an innovative analytical cycle that includes the use of disposable devices, which make BAµE much more user-friendly and suitable for the routine work, being a remarkable analytical alternative for trace analysis of priority compounds in real matrices.

A novel 3D-printed solid phase microextraction device equipped with silver-polyaniline coated pencil lead for the extraction of phthalate esters in cosmeceutical products

A screw-based portable and simple solid phase microextraction device was fabricated by a 3D printer and used in combination with the developed silver-incorporated porous polyaniline film pencil lead solid-phase microextraction fiber (Ag/PANI SPME). Scanning electron microscopy revealed a porous structure of the electrodeposited Ag/PANI film. The spectrum from energy dispersive x-ray spectroscopy (EDS) and the elemental map confirmed the presence of silver in the porous polymer film. It was used under stirring for the extraction of five phthalate esters: dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP) and di-2-ethylhexyl phthalate (DEHP). The extracted solution was identified and quantified by gas chromatography using a flame ionization detector (GC-FID). Under the optimum conditions of the developed method, a good linearity was obtained in a concentration range of 5.0–1000 μg L−1 for all five phthalate esters with limits of detection (LODs) of 4.41 ± 0.91 μg L−1, 3.98 ± 0.92 μg L−1, 3.65 ± 0.74 μg L−1, 4.91 ± 0.52 μg L−1 and 4.25 ± 0.66 μg L−1 for DMP, DEP, DBP, BBP and DEHP, respectively. The developed method provided good precision when tested with standard solutions (RSD < 5.5%, n = 6) and real samples (RSD < 3.4%, n = 6). Good fiber-to-fiber reproducibility was also confirmed by extraction with six newly prepared fibers; recoveries ranged from 81.09 ± 0.54% to 92.92 ± 0.46% with RSD <6.6%. The developed method was used to determine phthalate esters in 14 cosmeceutical samples. In rubbing alcohol samples, DEP and DEHP were detected at 7.03 ± 0.76 μg L−1 and 5.89 ± 0.53 μg L−1, respectively, while in contact lens cleaners, DEHP was found in a concentration range from 5.3 ± 1.1 μg L−1 to 6.8 ± 1.2 μg L−1. No phthalate esters contamination was detectable in saline solutions, eye cleaners and antibacterial disinfectant liquids. Recoveries in the range of 81.92 ± 0.99% to 102.4 ± 1.1% indicated the good accuracy of the developed method.

Single-use porous thin film extraction with gas chromatography atmospheric pressure chemical ionization tandem mass spectrometry for high-throughput analysis of 16 PAHs

The need for high throughput, reliable analytical methods for environmental analysis has driven our development of novel sampling technologies that can be used in microextraction devices and integrated into chromatographic systems for fast analysis. Here we report a new method of water analysis for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) that relies on a tailor made porous polymeric film for extraction with analysis by gas chromatography with atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS). The extraction device is user friendly, single-use and gives exhaustive extraction from a relatively small volume (20 mL). The films show good stability, with excellent analytical performance. Critical factors affecting the extraction efficiency such as desorption solvent, desorption time, extraction agitation, and extraction time were studied and optimized. These thin films are cost effective and efficient for single use analysis, but carry-over studies showed that the films can be reused at least 10 times without extensive washing and with no loss in performance. The 16 PAHs were measured with excellent limits of detection ranging from 1 pg mL−1 for BaA to 100 pg mL−1 for Flu and linearity (R2 > 0.997) over the 1–50,000 pg mL−1 concentration range. This high throughput method (1-h extractions, which can be completed simultaneously) showed good reproducibility (<20%) with recoveries in the range of 19.0–40.6% and concentration factors varying between 37.9 and 81.1. Analysis of real seawater and river water samples using matrix-matched calibration in synthetic seawater and river water showed only small matrix effects maintaining high sensitivity (LODs:1–100 pg mL−1), demonstrating that the films are suitable for analysis of real samples without the need for standard addition.

Development, Optimization and Applications of Thin Film Solid Phase Microextraction (TF-SPME) Devices for Thermal Desorption: A Comprehensive Review

Through the development of solid phase microextraction (SPME) technologies, thin film solid phase microextraction (TF-SPME) has been repeatedly validated as a novel sampling device well suited for various applications. These applications, encompassing a wide range of sampling methods such as onsite, in vivo and routine analysis, benefit greatly from the convenience and sensitivity TF-SPME offers. TF-SPME, having both an increased extraction phase volume and surface area to volume ratio compared to conventional microextraction techniques, allows high extraction rates and enhanced capacity, making it a convenient and ideal sampling tool for ultra-trace level analysis. This review provides a comprehensive discussion on the development of TF-SPME and the applications it has provided thus far. Emphasis is given on its application to thermal desorption, with method development and optimization for this desorption method discussed in detail. Moreover, a detailed outlook on the current progress of TF-SPME development and its future is also discussed with emphasis on its applications to environmental, food and fragrance analysis.

Fabric phase sorptive extraction for simultaneous observation of four penicillin antibiotics from human blood serum prior to high performance liquid chromatography and photo-diode array detection

Fabric phase sorptive extraction (FPSE), a current and up-to-date technique of solid sorbent-based microextraction, is regarded to be the basis of the development and advancement of an environmentally friendly, simple, sensitive, trustworthy, and fast analytical method by making use of high performance liquid chromatography and photo-diode array detection (HPLC-PDA) for the concurrent determination of four penicillin antibiotics residues (benzylpenicillin, cloxacillin, dicloxacillin and oxacillin) in human blood serum. By means of FPSE, the sophisticated material properties of sol-gel derived extraction and microextraction sorbents and the rich surface chemistry of an inherent porous and hydrophilic cellulose fabric substrate are successfully combined, leading to a flexible microextraction device which is characterized by high efficiency in extracting target analytes directly from complex sample matrices. Solvent evaporation and reconstitution steps, which are considered to be rather time-consuming, were eradicated successfully from the sample preparation workflow, organic solvent consumption was brought to a minimum while protein precipitation was assessed as impractical. Thus, FPSE complies with all green analytical chemistry (GAC) criteria. The microextraction device is characterized by a very high chemical and solvent stability owing to the strong chemical bonds formed between the sol–gel sorbent and the substrate. Thus, any organic solvent/solvent mixture can serve as the eluent/back-extraction solvent. Herein, sol-gel poly(tetrahydrofuran) coated FPSE membrane provided optimum extraction sensitivity for the selected penicillin antibiotics, which were analyzed using an RP-HPLC method, validated in terms of sensitivity, linearity, accuracy, precision, and selectivity. For all four penicillin antibiotics, the limit of detection and the limit of quantitation were 0.15 ng/μL and 0.5 ng/μL, respectively.

Bar adsorptive microextraction coated with multi-walled carbon nanotube phases - Application for trace analysis of pharmaceuticals in environmental waters

Bar adsorptive microextraction devices were modified with multi-walled carbon nanotubes for the first time. A bar adsorptive microextraction method followed by microliquid desorption and high-performance liquid chromatography with diode array detection was developed for the determination of trace levels of ketoprofen, diclofenac, gemfibrozil and mefenamic acid in water samples. The mean parameters affecting the bar adsorptive microextraction and microliquid desorption efficiency were studied and optimized using a univariate optimization strategy. The methodology was validated in terms of linearity, limits of detection and quantification, recovery, intra- and inter-day precision, accuracy, and matrix effect.The developed method showed lower limits of quantification of 0.35 μg L−1, calibration curves from 0.35 up to 1000.0 μg L−1 and determination coefficients higher than 0.9917. Recoveries in tap, surface, sea and waste water samples at three spiking levels were between 70.2 and 117.3% for all the pharmaceuticals. The coefficients of variation values for intra- (n = 6) and inter-day precisions (n = 18) were below 9.7%. The proposed analytical methodology allowed preconcentration factors up to 250 and proved to be cost-effective, easy to operate and environmentally friendly.

Determination of Volatile Components from Live Water Lily Flowers by an Orthogonal-Array-Design-Assisted Trapping Cell

A convenient and easy-moving, modified, headspace solid-phase microextraction (HS-SPME) device was developed for monitoring a living plant’s volatile organic compounds (VOCs). It consisted of a polyethylene terephthalate (PET) bottle as a sampling chamber, and certain variables were considered when using the HS-SPME device, including the material used and the fiber position, the direction of the airstream, and the distance between the sample and the fan. The results from varying those factors, generated by the orthogonal array design (OAD) method, were used to optimize the modified HS-SPME conditions. Based on the current literature regarding extracting fragrances by SPME, we selected polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polydimethylsiloxane (PDMS) as the fiber materials. Using the OAD method, PDMS/DVB was found to be the better fiber material when it was parallel to the fan, and also when the airstream provided positive pressure to the sample with the fan near the sample. The device was used to sample biogenic volatile compounds emitted from fresh Nymphaea caerulea (water lily) flowers, followed by gas chromatography-mass spectrometry (GC-MS) analysis. For the method validation, under the optimum conditions, the calculated detection limit value of the model compound (butyl decanoate) was 0.14 ng on column, which was equal to 1.41 ppm for the injection. The relative standard deviations of the intra-day and inter-day precisions were 1.21% and 3.05%. Thirty-three compounds were separated and identified. The main components in the vapor phase of N. caerulea were benzyl acetate (10.4%), pentadecane (15.5%), 6,9-heptadecadiene (40.1%), and 8-heptadecene (15.3%).

An in-needle solid-phase microextraction device packed with etched steel wires for polycyclic aromatic hydrocarbons enrichment in water samples.

A novel, low-cost and effective in-needle solid-phase microextraction device was developed for the enrichment of trace polycyclic aromatic hydrocarbons in water samples. The in-needle solid-phase microextraction device could be easily assembled by inserting hydrofluoric acid-etched wires, which were used as adsorbent, into a 22-gauge needle tube within spring supporters. Compared with the commercial solid-phase microextraction fiber, the developed device has higher efficiency for the extraction of polycyclic aromatic hydrocarbons with four to six rings from water samples using the optimized extraction conditions. With gas chromatography equipped with a flame ionization detector, the limits of detection for the polycyclic aromatic hydrocarbons with four to six rings ranged from 0.0020 to 0.0067ng/mL. The relative standard deviations for one needle and needle-to-needle extractions were in the range of 5.2-9.9% (n=5) and 3.4-12.3% (n=5), respectively. The spiked recoveries of the polycyclic aromatic hydrocarbons in tap water samples ranged from 73.2 to 95.4%. This in-needle solid-phase microextraction device could be a good field sampler because of the low sample loss over a long storage time.

Phenyl propyl functionalized hybrid sol–gel reinforced aluminum strip as a thin film microextraction device for the trace quantitation of eight PCBs in liquid foodstuffs

In the present study, a low-cost, convenient and reliable thin film coating was developed as the extraction phase. The new sorbent was obtained by chemical bond formation between the hybrid sol-gel precursors and aluminum strip substrate in the first step and subsequent functionalization by phenyl propyl groups. The surface properties of the synthesized sorbent were characterized by Fourier transform infrared spectroscopy (FT–IR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Eight polychlorinated biphenyl (PCB) homologs were effectively extracted by using the self-made device in thin film microextraction (TFME) set-up followed by gas chromatography-mass spectrometry (GC-MS) determination. The influencing factors, including extraction and desorption solvent, desorption solvent volume, extraction and desorption time, extraction temperature, agitation speed, salt addition, and matrix effect were investigated. Under the optimized conditions, the limits of detection (at S/N ratio of 3) were found to be 1–3 ng L−1 and the linearity was in the range of 10–1000 ng L−1. The method precision values calculated as relative standard deviations (RSDs%), were in the range of 6.8–11.0% (intra–day), and 9.0–12.4% (inter–day). This work was successfully applied to enrichment and trace levels determination of PCB congeners in orange juice, cola drink, milk, beer, and honey. The evaluations also showed satisfactory recoveries (70.6–103.5%) for different spiked real samples.

In-line coupling of supported liquid membrane extraction across nanofibrous membrane to capillary electrophoresis for analysis of basic drugs from undiluted body fluids.

Planar polyamide 6 nanofibrous membrane was for the first time used in direct coupling of supported liquid membrane (SLM) extraction to CE analysis. Disposable microextraction device with the nanofibrous membrane was preassembled and stored for immediate use. The membrane in the device was impregnated with 1 µL of 1-ethyl-2-nitrobenzene and the device was subsequently filled with 10 µL of acceptor solution (10 mM HCl) and 15 µL of donor solution (sample). The device was in-line coupled to CE system for selective extraction and direct injection, separation and quantification of model basic drugs (nortriptyline, haloperidol, loperamide and papaverine) from standard saline solutions (150mM NaCl) and from undiluted human body fluids (urine and blood plasma). Compared to standard polypropylene supporting material, the nanofibrous membrane demonstrated superior characteristics in terms of lower consumption of organic solvents, constant volumes of operational solutions, full transparency and possibility to preassemble the devices. Extraction parameters were better or comparable for the nanofibrous vs. the polypropylene membrane and the hyphenated SLM-CE method with the nanofibrous membrane was characterized by good repeatability (RSD ≤ 11.3%), linearity (r2 ≥ 0.9953; 0.5-20mg/L), sensitivity (LOD ≤ 0.4mg/L) and transfer (27-126%) of the basic drugs.

Assessing Organic Chemical Emissions and Workers’ Risk of Exposure in a Medical Examination Center Using Solid Phase Microextraction Devices

ABSTRACT Needle trap samplers (NTS), which are environmentally friendly solid phase microextraction sampling devices, were used to obtain air samples at a medical examination center in a teaching hospital to determine the concentration of airborne xylene. The standard active sampling method, Method 1501, was simultaneously used to evaluate the exposure of workers to xylene. The concentrations of xylene were much lower than the legal 100-ppm time-weighted average (TWA) concentration. Another organic reagent used in the medical examination center, formaldehyde, did not exhibit co-adsorption along with the extraction of xylene by NTS. The use of a fume hood satisfactorily reduced VOC emissions in the workplace. Additionally, a management strategy involving chemical control banding was adopted to evaluate the emission control of xylene and formaldehyde in this work. We recommend that workers wear the NTS as a routine micro-sampler in order to protect their health.

Fabrication of graphene oxide incorporated polymer monolithic fiber as solid phase microextraction device for determination of organophosphate esters in soil samples

A novel solid phase microextraction fiber named graphene oxide incorporated poly acrylamide-ethylene glycol dimethacrylate (GO-poly AM-EDGMA) monolithic fiber has been successfully prepared in a fused silica capillary tube (250 μm, i.d.) via thermally initiated polymerization using acrylamide (AM) as the monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, dimethylformamide dispersed by GO as porogens, and then obtained by removing 1 cm wall from one end of the fused silica capillary tube. The fiber has large surface area (536 m2 g−1), pore capacity (0.694 cm3 g−1) good thermal stability (up to 320 ℃), long service life and good reproducibility (RSD ＜5% throughout 110 times) which facilitated for high throughput headspace solid phase microextraction (HS-SPME) coupled to gas chromatograph (GC) analysis. The HS-SPME/GC method using the new fiber was evaluated by the determination of five organophosphate esters (OPEs) in soil samples coupled to flame photometric detector (FPD). The proposed HS-SPME-GC/FPD method yielded satisfactory limits of quantification (0.03 ng g−1∼0.24 ng g−1); linearity (≥0.99), good intra- and inter-day precision expressed as relative standard deviations for a single fiber were in the range of 5.2–9.0% and 4.8–9.0%, respectively, and fiber-to-fiber reproducibility was in the range of 5.9–9.7%. The method was applied for the analysis of OPEs in environmental soil samples and the relative recoveries were found to be in the range from 80.1 to 105.6%. Based on these features, the new fiber has great potential for widespread use as a high throughput trace analysis tool.

Enhancing enrichment ability of a nanoporous carbon based solid-phase microextraction device by a morphological modulation strategy

Recent works of designing excellent adsorbents emphasized on the specific surface areas and porosities of the materials. This study presents the influence of morphological modulation on extraction efficiencies of materials for the first time. Sea urchin-like nanoporous carbon (NPC), derived from metal organic framework (MOF), was synthesized and fabricated as solid phase microextraction (SPME) device. The morphological modulated structure of the NPC, with enhanced effective adsorption sites produced by the pointed and sharp edges, could improve the extraction efficiencies of the NPC. Comparing with the unmodulated one, NPC with morphological modulation possessed higher extraction efficiencies (2 flod) as well as accelerated sampling rates (5 flod) on benzene series compounds (BTEX), improving the sensitivity of the sampling method (limits of detection ranged from 0.08 ng L−1 to 0.36 ng L−1). Moreover, it was also the first time that the moisture sensitive MOF-derived NPC was exploited as the SPME adsorbent. In general, this study was expected to be an important advance in broadening the approaches on designing a superior SPME adsorbents not only emphasizing on the specific surface area as well as porosity but also the morphology.

Development of a Hydrophilic Lipophilic Balanced Thin Film Solid Phase Microextraction Device for Balanced Determination of Volatile Organic Compounds.

A novel hydrophilic-lipophilic balanced (HLB) thin film solid-phase microextraction (TF-SPME) device is proposed for polarity-balanced determinations of volatile organic compounds. The proposed HLB particles used in the preparation of these membranes were prepared using a precipitation polymerization technique and determined to have a specific surface area of 335 m2/g with an average pore diameter of 13 Å. Membranes prepared from these particles were found to extract 1.8, 2.2, 1.9, 1.7, 2.0, and 1.3 times more benzene, 2-pentanone, 1-nitropropane, pyridine, 1-pentanol, and octane, respectively, than the established divinylbenzene/polydimethylsiloxane (DVB/PDMS)-based membranes. Furthermore, membranes prepared from these lab-made particles were shown to extract significantly ( p = 0.00047) larger amounts of these analytes than membranes prepared from comparative commercial HLB particles. The intermembrane extraction efficiency between 3 membranes was determined to be reproducible at 95% confidence for 4 different coating chemistries tested, including the DVB/PDMS membranes, and those prepared with 3 different HLB compositions. Furthermore, method reliability was established by confirming that, once extracted, modified McReynolds standards were stable on the HLB/PDMS membranes stored in thermal desorption tubes on an autosampler rack for at least 120 h, for 5 of the 6 standards, but only for 24 h for pyridine at a 95% level of confidence. Finally, using a TF-SPME enabled, portable GC/MS instrument, an entirely on-site proof of concept application was performed for the determination and quantitation of chlorination byproducts in a private hot tub, successfully identifying chloroform, bromodichloromethane, dichloroacetonitrile, chlorobenzene, benzonitrile, and benzyl chloride, while further quantifying chloroform and dichloroacetonitrile at levels of 270 and 79 ppb with %RSD values of 13% and 5%, respectively.