Commercial Solid-phase Microextraction Fibers Research Articles

Post-synthetic modification of covalent organic framework for efficient adsorption of organochlorine pesticides from cattle's milk

Analysis of organochlorine pesticides (OCPs) residues in milk faces a significant challenge. Herein, a sea urchin structured covalent organic framework bearing boric acid groups named COF-B(OH)2 was synthesized and applied as a coating material for solid-phase microextraction (SPME) of the OCPs in cattle’s milk. Its performance was superior to that of three commonly used commercial SPME fibers, which could be due to the coexistence of hydrogen bonding, halogen bonding, π-stacking and electrostatic interactions. Besides, the fiber coating displayed good stability and reusability. After optimization, a COF-B(OH)2 based SPME coupled with gas chromatography-electron capture detection was established for the sensitive detection of the OCPs from milk samples. The limits of detection (S/N = 3) were between 0.04 and 1.0 μg kg−1. Satisfactory accuracy was achieved with the method recoveries in the range of 87.5 % to 112.5 %. These results manifest the feasibility of the COF-B(OH)2 coated fiber for the enrichment of the trace OCPs from milk samples.

A durable hydrophobicity hydrazone covalent organic framework coating for solid phase microextraction of polycyclic aromatic hydrocarbons in food and environmental sample

In this study, a durable hydrophobicity hydrazone covalent organic framework (BTCH-PTA-COF) has been developed as fiber coating, which was applied to solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The hydrophobic and π-π packing interactions between BTCH-PTA-COF and PAHs were confirmed by contact angle experiments and Van der Waals surface electrostatic potential analysis. Further, large specific surface area, good chemical and thermal stability have positive promoting effect on extraction. The method of wide linearity (0.25–300 µg·L−1), low detection limits (0.03–0.05 µg·L−1) and high enrichment factors (767–1411) for the detection of PAHs is explored, coupling BTCH-PTA-COF based SPME with gas chromatography with hydrogen flame detector (GC-FID). The relative standard deviations (RSDs) for inter-day and intra-day extractions of PAHs are ranging from 4.1 % to 9.6 % and 2.9 % to 6.4 %, respectively. The method successfully detected and quantified trace PAHs in tea beverages and river water samples with recoveries from 88.5 % to 104.8 %. The BTCH-PTA-COF coated fiber is ultra-stable in recycled extraction and reused at least 120 times, which could surpass published and commercial SPME fiber.

Hierarchical porous MOFs@COFs-based molecular trap solid-phase microextraction for efficient capture of PAHs and adsorption mechanisms

In view of the serious carcinogenic, teratogenic and mutagenic properties of polycyclic aromatic hydrocarbons (PAHs), which cause significant harm to human beings and the environment. Therefore, developing rapid adsorption and efficient analytical methods are research topic with practical significance. Herein, an innovative MOFs@COFs-based molecular trap materials were prepared with hierarchical porous core–shell structure and used as solid-phase microextraction (SPME) fiber coating, which combined with high performance liquid chromatography (HPLC) to achieve the efficient separation, capture, and detection for 7 PAHs in real samples. The possible adsorption mechanism was systematically verified and explained. Under the optimized conditions, the method developed in this experiment had a wide linear range (0.005–400 µg·L−1) with a good linear correlation coefficient (R2 > 0.9984), low detection limits (0.002–0.405 µg·L−1, S/N = 3) and low quantification limits (0.005–1.351 µg·L−1, S/N = 10). The relative standard deviations of individual fibers and different batches of fibers were 0.26–3.64% and 0.40–5.91%, respectively. Besides, the fiber showed higher enrichment capacity and extraction efficiency for PAHs compared to commercial SPME fibers and other material fibers, and exhibited excellent acid-base stability and reproducibility. This work provided a favorable synthetic pathway for the preparation of MOFs@COFs composites by layer-modified assembly synthesis strategy, showed excellent practical applicability as a SPME fiber coating combined with HPLC, and could be realized to provide technical support for future studies on the separation, adsorption, and analysis of PAHs in the petrochemical industrial zone of the Yellow River Basin.

A Hybrid Stainless-Steel SPME Microneedle Electrode Sensor for Dual Electrochemical and GC-MS Analysis.

A mechanically robust in-tube stainless steel microneedle solid phase microextraction (SPME) platform for dual electrochemical and chromatographic detection has been demonstrated. The SPME microneedle was fabricated by layer-by-layer (LbL) in-tube coating, consisting of carbon nanotube (CNT)/cellulose nanocrystal (CNC) film layered with an electrically conductive polyaniline (PANI) hydrogel layer (PANI@CNT/CNC SPME microneedle (MN)). The PANI@CNT/CNC SPME MN showed effective analysis of caffeine by GC-MS with an LOD of 26 mg/L and excellent precision across the dynamic range. Additionally, the PANI@CNT/CNC SPME MN demonstrated a 67% increase in sensitivity compared to a commercial SPME fiber, while being highly robust for repeated use without loss in performance. For electrochemical detection, the PANI@CNT/CNC SPME MN showed excellent performance for the detection of 3-caffeoylquinic acid (3-CQA). The dynamic range and limits of detection (LOD) for 3-CQA analysis were 75-448 mg/L and 11 mg/L, respectively. The PANI@CNT/CNC SPME MN was demonstrated to accurately determine the caffeine content and 3-CQA in tea samples and dark roast coffee, respectively. The PANI@CNT/CNC SPME MN was used for semiquantitative antioxidant determination and composition analysis in kiwi fruit using electrochemistry and SPME-coupled GC-MS, respectively.

A multi-site recognition molecularly imprinted solid-phase microextraction fiber for selective enrichment of three cross-class environmental endocrine disruptors.

Molecularly imprinted solid-phase microextraction fibers with multi-site recognition were prepared for the simultaneous enrichment of three cross-class environmental endocrine disruptors (EEDs) in environmental water. The surface morphology of the multi-site recognition molecularly imprinted fibers was characterized using scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and surface area and pore size analyzer. Under optimal extraction conditions, the molecularly imprinted fibers showed higher extraction capacity to bisphenol F, diethyl phthalate, and methyl paraben than non-imprinted polymer fibers and commercial fibers. Compared with commercial solid-phase microextraction fibers, the multi-site recognition molecularly imprinted fibers showed superior extraction performance at different concentrations of analytes. The selectivity study confirmed that the multi-site recognition molecularly imprinted solid-phase microextraction fibers were highly selective not only for specific template molecules but also for bisphenols, parabens, and phthalates. Furthermore, the method achieved a limit of detection of 0.003-0.02 μg L-1 for the three cross-class EEDs in environmental water samples with recoveries ranging from 75.76% to 112.69% and relative standard deviations below 11.46%. Thus, the novel MIP fibers with multi-site recognition prepared in this work have provided a promising approach in the field of specific adsorption and a strategy for the simultaneous and sensitive monitoring of multiple cross-class trace EEDs.

Facile fabrication of a novel SPME fiber based on silicone sealant/hollow ZnO@CeO2 composite with super-hydrophobicity for the enhanced capture of pesticides from water

Herein, a novel solid phase microextraction (SPME) fiber coating based on silicone sealant/hollow ZnO@CeO2 composite with super-hydrophobicity was designed, which could capture rapidly and determine efficiently-six pesticides combined with high-performance liquid chromatography (HPLC). The synthesis mechanism of ZnO@CeO2 with core–shell structure was discussed. Under the optimized conditions, the developed method showed a wide linear range (0.026–200 µg/L) with good linearity (R2 greater than 0.9988), low detection limits (0.008–0.353 µg/L, S/N = 3), and quantification limits (0.026–1.175 µg/L, S/N = 10) for six pesticides. The relative standard deviations (RSD) of single fiber and different batches of fibers were 0.4–4.8 % and 0.6–5.3 %, respectively. In addition, compared with the commercial SPME fiber, the fiber showed better enrichment ability and extraction efficiency for pesticides, which might be due to the solid π-π accumulation, hydrophobic interaction, abundant adsorption sites, and hydrogen bonding between the coating and the target analyte. Besides, the hollow structure of the composite material, the rare earth metal oxide CeO2 on the surface of the coating, and the silicone sealant all played a crucial role in the extraction process. Finally, the method had been successfully applied to determine the pesticides in real water samples, with the recovery rate ranging from 80.1 % to 108.2 % and RSD < 5.67 %. The experimental results showed that the Ss/ZnO@CeO2 with a hollow core–shell structure had great application potential as a composite coating for solid-phase microextraction.

Facile one-step synthesis of graphene oxide/polyhedral oligomeric silsesquioxane composite-coated fiber for high-efficiency solid-phase microextraction of polycyclic musks

Efficient fabrication of excellent fiber coatings for high-performance solid-phase microextraction (SPME) is interesting. Here, a high-efficiency synthesis strategy on graphene oxide/polyhedral oligomeric silsesquioxane (GO/POSS) composite-coated fiber was exploited via an ultra-fast UV polymerization in one step, and applied to excellent SPME of polycyclic musks (PCMs). Using methacryloxy siloxane-grafted GO and POSS-methacryl substituted (POSS-MA) as functional monomers, a facile and direct UV polymerization of multiple reactions including alkenyl radical reaction and thiol-ene click chemistry was fulfilled on thiol-pretreated fiber in only 5 min without tedious process. Characteristics such as morphology, FT-IR, XPS, BET and TG of fiber coating were studied in detail, as well as the SPME performance. Attributing to the rigid stereo conformation of POSS and large conjugate plane of GO-based nanosheet, the significant surface area, high hydrophobicity and intrinsic π-π interactions were adopted in fiber coating. In comparison of commercial SPME fibers, POSS-based or GO-based SPME fibers, a superior extraction performance towards PCMs was achieved with GO/POSS-coated fiber. High-efficiency extraction of PCMs was gained with prominent enrichment factors and the sensitive detection limits of PCMs were of 0.04–0.12 ng/L. In particular, the extraction efficiency was robust and still maintained a high level above 93% for PCMs even after 150 cycle's applications. Good recoveries of PCMs reached 86.6%–102.1% and 86.7%–101.3% in river water and cosmetic samples, respectively. It lights an attractive approach to efficiently fabricating robust GO/POSS-coated fiber for high-performance SPME of PCMs.

Mussel Inspired Polydopamine as Silica Fibers Coating for Solid-Phase Microextraction

Commercial solid-phase microextraction fibers are available in a limited number of expensive coatings, which often contain environmentally harmful substances. Consequently, several different approaches have been used in the attempt to develop new sorbents that should possess intrinsic characteristics such as duration, selectivity, stability, and eco-friendliness. Herein we reported a straightforward, green, and easy coating method of silica fibers for solid-phase microextraction with polydopamine (PDA), an adhesive, biocompatible organic polymer that is easily produced by oxidative polymerization of dopamine in mild basic aqueous conditions. After FT-ATR and SEM characterization, the PDA fibers were tested via chromatographic analyses performed on UHPLC system using biphenyl and benzo(a)pyrene as model compounds, and their performances were compared with those of some commercial fibers. The new PDA fiber was finally used for the determination of selected PAHs in soot samples and the results compared with those obtained using the commercial PA fiber. Good reproducibility, extraction stability, and linearity were obtained using the PDA coating, which proved to be a very promising new material for SPME.

Preparation of a Novel Solid Phase Microextraction Fiber for Headspace GC-MS Analysis of Hazardous Odorants in Landfill Leachate

The practice of odorant analysis can often be very challenging because odorants are usually composed of a host of volatile organic compounds (VOCs) at low concentrations. Preconcentration with solid phase microextraction (SPME) is a conventional technique for the enrichment of these volatile compounds before analysis by headspace gas chromatography-mass spectrometry (GC-MS). However, commercially available SPME products usually bear the defects of weak mechanical strength and high cost. In this work, novel SPME fibers were prepared by a one-pot synthesis procedure from divinylbenzene (DVB), porous carbon powder (Carbon) and polydimethylsiloxane (PDMS). Factors that influence the extraction efficiency, such as extraction temperature, extraction time, salting effects, pH, stirring rate, desorption temperature and time, were optimized. VOCs in landfills pose a great threat to human health and the environment. The new SPME fibers were successfully applied in the analysis of VOCs from the leachate of a cyanobacteria landfill. Quantification methods of major odor contributors were established, and a good linearity (r &gt; 0.998) was obtained, with detection limits in the range of 0.30–0.50 ng/L. Compared to commercial SPME fibers, the new material has higher extraction efficacy and higher precision. Hence, it is suitable for the determination of hazardous odorants of various sources.

Integration of a micropreconcentrator with solid-phase microextraction for analysis of trace volatile organic compounds by gas chromatography-mass spectrometry

The analysis of toxic volatile organic compounds (VOCs) in environmental air is important because toxic VOCs induce adverse effects on human health. Although gas chromatography- mass spectrometry (GC–MS) is the standard instrument for analysis of trace VOCs in air, this mode of analysis requires preconcentration and cryogenic processes. The preconcentration and subsequent thermal desorption of VOCs require special instruments and a long time of processing sample that significantly limit applications of GC–MS for monitoring indoor and outdoor VOC levels. Using a microfabricated preconcentrator for VOC analysis also has the challenge of a large sample volume for concentration. Using solid-phase microextraction (SPME) for VOC analysis by GC–MS often approaches the limit of detection of the GC–MS instrument for trace VOCs in air. This work reports a simple method to integrate microfabricated preconcentrators with commercial SPME fibers in a two-stage concentration processes to achieve rapid and reliable measurement of trace VOCs in air by GC–MS. We designed and fabricated a preconcentrator with micropillars in a microfluidic chamber to support sorbents and to increase the heat transfer rate to the sorbents for rapid thermal desorption. The effects of air flow rates through the preconcentrator on VOCs adsorption and thermal desorption were optimized for increasing analytical accuracy of VOCs measurements. The integration of a micropreconcentrator with SPME enabled measurements of sub-ppb levels of benzene, toluene, ethylbenzene, and xylene (BTEX), and trichloroethylene (TCE) in environmental air by GC–MS.

Ketoenamine Covalent Organic Framework Coating for Efficient Solid-Phase Microextraction of Trace Organochlorine Pesticides.

Fiber coating is a key part of solid-phase microextraction (SPME) technology, and it determines the selectivity, sensitivity, and reproducibility of the analytical method. A ketoenamine covalent organic framework called Tp-Azo-COF with rich electronegative N atoms was prepared as an SPME coating in this work. The Tp-Azo-COF coating had a large surface area of 1218 m2 g-1 and good thermal and chemical stability, and it was applied for the extraction of organochlorine pesticides (OCPs). According to quantum chemistry calculations, the adsorption affinity of the Tp-Azo-COF coating for five OCPs was primarily affected by the halogen bond and hydrophobicity interaction. The extraction efficiencies of the Tp-Azo-COF coating for five OCPs were higher than those of three commercial SPME fiber coatings, and the enrichment factors ranged from 1061 to 3693. When combined with gas chromatography-tandem mass spectrometry, a wide linear range (0.1-1000 ng L-1), low limits of detection (0.002-0.08 ng L-1), and good fiber-to-fiber accuracy (4.3-10.9%) were achieved under optimal conditions. Moreover, the applicability of the developed method was evaluated by analyzing four samples (milk, green tea, tap water, and well water), and the recoveries were in the range of 83.4-101.6%, with relative standard deviations <8.6%. This research extends the application of the stabilized ketoenamine COF as a sample enrichment probe for OCP analysis.

Nitrogen-doped porous biochar derived from marine algae for efficient solid-phase microextraction of chlorobenzenes from aqueous solution

Nitrogen-doped porous biochar (NPB) with a large specific surface area, wide pore size distribution, graphitized structure, nitrogen doping, and hydrophobicity was fabricated by high-temperature modification of algal biochar with potassium carbonate. This NPB was then uniformly coated on stainless steel wire as a novel solid-phase microextraction (SPME) fiber. The extraction efficiency of NPB-coated fiber for seven chlorobenzenes (CBs) was excellent; it was 1.0–112.2 times higher than that of commercial SPME fibers. A trace determination method was developed for seven CBs in water with the optimized extraction conditions by NPB-coated fiber and gas chromatography–electron capture detector, which showed wide linear ranges (1–1000 ng L−1), low detection limits (0.007–0.079 ng L−1), great repeatability (2.5–6.5% for intra-day, and 3.1–6.8% for inter-day), and excellent reproducibility (3.5–6.3%, n = 5). The practicality of the developed method was evaluated using real water samples and showed great recoveries (89.55–105.19%). This study showed that low-cost biomass wastes could be converted to advanced biochar materials by a facile method, and displayed excellent performance in SPME applications.

Sputtered silicon solid phase microextraction fibers with a polydimethylsiloxane stationary phase with negligible carry-over and phase bleed

We report the preparation of high performance, sputtered, polydimethylsiloxane (PDMS)-coated solid phase microextraction (SPME) fibers that show negligible carry-over and phase bleed. This process involves sputtering silicon onto silica fibers and functionalizing the resulting porous nanostructures with ultrathin films of vapor-deposited PDMS. Different thicknesses of silicon (0.25, 0.8, and 1.8 µm) and PDMS (8, 16, and 36 nm) were produced and their extraction efficiencies evaluated. The deposition of PDMS was confirmed by time-of-fight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and contact angle goniometry on model, planar silicon substrates. These fibers were investigated using direct immersion SPME coupled with gas chromatography-mass spectrometry (GC–MS) analysis of a series of polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic pollutants. The 1.8 µm thick silicon coating with 16 nm of PDMS (Si (1.8 µm)/PDMS (16 nm)) produced the best response among the combinations tested. Conditions for the extraction of PAHs with this fiber were optimized and its extraction performance was compared to that of a commercial 7 μm PDMS fiber. The linearity (1–110 µgL−1), repeatability (RSD%, n = 3) (17% ave.), and minimum detection limits (0.6–1.5 µgL−1) of the sputtered fibers were determined and found to be superior to the commercial 7 µm PDMS fiber in many respects. Carry-over and phase bleed from commercial PDMS-based SPME fibers are two of their major drawbacks, which decrease their lifetimes and usefulness. Minimal carry-over and phase bleed were observed for our sputtered PDMS-coated fibers. In particular, our fiber only shows 12% of the phase bleed of the comparable commercial fiber. In addition, it shows no carry-over for analytes with retention times greater than pyrene, and only 5% of the carry-over of the other analytes. Our fibers could be used for at least 300 injections without any significant loss of performance.

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.

Determination of Phthalate Esters in Water and Coffee by Solid‐Phase Microextraction Using Vinyl Terminated Imidazolium Based Ionic Liquid Grafted on Graphene Oxide Coatings

AbstractA series of novel ionic liquids (1‐(3‐aminopropyl)‐3‐vinyl imidazolium bromide/tetrafluoroborate) grafted onto graphene oxide‐ coated stainless‐steel wires by a sol‐gel technique were fabricated and used as solid‐phase microextraction (SPME) fibers for the determination of phthalate esters (PAEs) in water and coffee by a direct immersion‐SPME‐gas chromatography‐mass spectrometry (DI‐SPME‐GC‐MS) method. The effect of pH, stirring rate, ionic strength, extraction temperature and extraction time were examined for each home‐made fiber. Under optimized conditions, the proposed method displayed wide linearity (0.01‐500 μg L−1), good repeatability (0.26‐13.30%; n=3), and low limit of detections (LODs, 5–30 ng L−1). The home‐made fibers had good durability and could be used for more than 120 sorption/desorption cycles. The fiber‐to‐fiber reproducibility was in the range of 1.53‐4.53% for 100 μg L−1. The method was successfully performed on tap water, seawater and coffee samples with recoveries from 87.6 to 100.7%. The extraction efficiencies of home‐made SPME fibers were satisfactorily comparable with those of PA and CAR/PDMS commercial SPME fibers.

Three-dimensional Pd/Pt bimetallic nanodendrites on a highly porous copper foam fiber for headspace solid-phase microextraction of BTEX prior to their quantification by GC-FID.

The preparation of bimetallic Pd/Pt nanofoam for use in fiber based solid-phase microextraction (SPME) is described. First, a highly porous copper foam was prepared on the surface of an unbreakable copper wire by an electrochemical method. Then, the substrate was covered with metallic Pd and Pt using galvanic replacement of the Cu nanofoam substrate by applying a mixture of Pd(II) and Pt(IV) ions. The procedure provided an efficient route to modify Pd/Pt nanofoams with large specific surface and low loading with expensive noble metals. The fiber was applied to headspace SPME of benzene, toluene, ethylbenzene and xylene (BTEX) (as the model compounds) in various spiked water and wastewater samples. It was followed by gas chromatography-flame ionization detection (GC-FID). A Plackett-Burman design was performed for screening the experimental factors prior to Box-Behnken design. Compared with the commercial PDMS SPME fiber (100μm), it had higher extraction efficiency for BTEX. Under the optimum conditions, the method has low limits of detection (0.16-0.35μgL-1), a wide linear range (1-200μgL-1), relative standard deviations between 5.8 and 10.5%, and good recoveries (>85% from spiked samples). Graphical abstract Schematic presentation of a three-dimensional Pd/Pt bimetallic nanodendrites supported on a highly porous copper foam fiber for use in headspace solid phase microextraction of BTEX. They were then quantified by gas chromatography-flame ionization detector.

β-Ketoenamine-linked covalent organic framework coating for ultra-high-performance solid-phase microextraction of polybrominated diphenyl ethers from environmental samples

Covalent organic frameworks (COFs) via Schiff base-type linkages (1,3,5-triformylphloroglucinol–paraphenylenediamine, TpPa-1), as an ideal coating, possesses significant potential for solid-phase microextraction (SPME) due to their fascinating properties, such as outstanding thermal and chemical stabilities, inherent porosity, and high crystallinity. A novel SPME device was fabricated based on TpPa-1 as an enrichment coating for capturing trace polybrominated diphenyl ethers (PBDEs). This TpPa-1 coating exhibited a superior enrichment capacity in “catching” PBDEs over commercial SPME fibers. Such performance is attributed to multiple factors, including the coating’s hydrophobic nature, π-π stacked architectures, large specific surface area, high thermal stability, and size-matching effect. High enhancement factors of 2035–6859, low detection limits of 0.0058–0.022 ng L−1, satisfactory linear range of 0.01–100 ng L−1, good repeatability of 4.86%–9.33%, and excellent reproducibility of 5.62%–9.85% were achieved. Finally, as expected, as the most sensitive SMPE technique for detecting PBDEs, to the best of our knowledge, the developed SPME procedure in combination with gas chromatography–negative chemical ion–mass spectrometry analysis was proven to be ultrasensitive, dependable, and practical in analyzing PBDE species in real water. These exceptional results signify that the proposed method offers a fresh prospect to extend the potential applications of COFs to pick up pollutants at ultra-low levels from environmental samples.

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.

The authors describe a new coating for use in solid-phase microextraction (SPME). Silver nanoparticles (AgNPs) were prepared by using gallic acid or glucose as the reducing agents, and then supported onto a stainless steel wire that was previously coated with a silver mirror. Coating with AgNPs was performed by a layer-by-layer approach of up to eight cycles of consecutive deposition of AgNPs and the thiol linker 1,8-octanedithiol. This procedure allows proper control of the coating thickness. Thicknesses are 3.2μm and 3.5μm with AgNPs obtained with gallic acid and glucose, respectively. This is in agreement with theoretical estimations (3.8μm). The fibers were used in the direct-immersion SPME-GC-FID determination of 16 polycyclic aromatic hydrocarbons (PAHs) from different waters. The performance of the method was compared to the one using polydimethylsiloxane fibers (100μm), which is the most suitable commercial SPME fiber for PAHs. Despite the low thickness of the AgNP coatings (compared to PDMS), the analytical features of the method using the most adequate coating (AgNPs prepared with gallic acid) include: (a) limits of detection down to 0.6ng·mL-1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) lower than 22, 26 and 25%, respectively; and (c) an operational lifetime of ~150 extractions/desorption cycles. The analysis of various spiked environmental waters using these fibers resulted in adequate analytical performance. Graphical abstract Silver nanoparticle based coatings for solid-phase microextraction fibers were prepared by a layer-by-layer approach. They were used for determination of 16 PAHs in waters by gas chromatography. Limits of detection are < 14μg·L-1 and intra-day, inter-day, and inter-fiber precisions are <26%.

Exploiting the tunable selectivity features of polymeric ionic liquid-based SPME sorbents in food analysis

In this work, the performances of polymeric ionic liquid (PIL) based solid-phase microextraction (SPME) coatings were assessed for applications concerning food safety and quality. Two different polymeric ionic liquid coatings, namely poly(1–4-vinylbenzyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl] imide (poly([VBHDIM][NTf2]), PIL 1, and N,N-didecyl-N-methyl-d-glucaminium poly(2-methyl-acrylic acid 2-[1-(3-{2-[2-(3-trifluoromethanesulfonylamino-propoxy)-ethoxy]-ethoxy}-propylamino)-vinylamino]-ethyl ester) (poly([DDMGlu][MTFSI]), PIL 2, were evaluated. The PIL-based coatings were compared to commercially available SPME coatings in terms of their performance toward extraction of pesticides and fruit metabolites. The partition coefficients (Kfs) of the tested coatings were calculated, with PIL 1 demonstrating similar or better performance compared to the commercial coatings. Design of experiment (DoE) was applied to optimize the parameters that most influenced SPME extraction, and a quantitative method for determination of 5 organophosphorus pesticides was developed by using PIL-based coatings and commercial SPME fibers. Despite the thin layer of the sorbent coating, PIL 1 achieved limits of quantitation at the low part-per-billion level. Moreover, in a comparative investigation of analyte coverage carried out via HS-SPME-GCxGC-ToF/MS with grape homogenate as model matrix, excellent performances were observed for the PIL-based coatings toward the determination of fruit metabolites, demonstrating their capability towards broad extractive coverage of analytes characterized by various physicochemical properties.

Preliminary construction of integral analysis for characteristic components in complex matrices by in-house fabricated solid-phase microextraction fibers combined with gas chromatography–mass spectrometry

Integral analysis plays an important role in study and quality control of substances with complex matrices in our daily life. As the preliminary construction of integral analysis of substances with complex matrices, developing a relatively comprehensive and sensitive methodology might offer more informative and reliable characteristic components. Flavoring mixtures belonging to the representatives of substances with complex matrices have now been widely used in various fields. To better study and control the quality of flavoring mixtures as additives in food industry, an in-house fabricated solid-phase microextraction (SPME) fiber was prepared based on sol-gel technology in this work. The active organic component of the fiber coating was multi-walled carbon nanotubes (MWCNTs) functionalized with hydroxyl-terminated polydimethyldiphenylsiloxane, which integrate the non-polar and polar chains of both materials. In this way, more sensitive extraction capability for a wider range of compounds can be obtained in comparison with commercial SPME fibers. Preliminarily integral analysis of three similar types of samples were realized by the optimized SPME-GC–MS method. With the obtained GC–MS data, a valid and well-fit model was established by partial least square discriminant analysis (PLS-DA) for classification of these samples (R2X=0.661, R2Y=0.996, Q2=0.986). The validity of the model (R2=0.266, Q2=−0.465) has also approved the potential to predict the “belongingness” of new samples. With the PLS-DA and SPSS method, further screening out the markers among three similar batches of samples may be helpful for monitoring and controlling the quality of the flavoring mixtures as additives in food industry. Conversely, the reliability and effectiveness of the GC–MS data has verified the comprehensive and efficient extraction performance of the in-house fabricated fiber.