Coated Solid-phase Microextraction Fiber Research Articles

Determination of aromatic amines in the urine of smokers using a porous organic framework (JUC-Z2)-coated solid-phase microextraction fiber

A solid-phase microextraction (SPME) fiber coated with a two-dimensional porous organic framework (POF), JUC-Z2, was synthesized by a sol-gel process. The JUC-Z2-coated SPME fiber was combined with gas chromatography-mass spectrometry/mass spectrometry (GC–MS/MS), and a direct analysis method without any derivatization step was developed for the determination of two major harmful aromatic amines (1-naphthylamine, 1-NA; 2-naphthylamine, 2-NA) in the urine of amokers. The new method exhibited satisfactory linearity in the wide range of 0.05–100 μg L−1 with correlation coefficients (R) of 0.9999. The limits of detection are 0.010 and 0.012 ng L−1. The relative standard deviations for repeated extraction (n = 6) with one fiber are less than 7.7%. The JUC-Z2-coated fiber demonstrates obviously superior extraction efficiencies for the two aromatic amines over the commercial fibers (CW/PEG, PA, PDMS/DVB, PDMS, CAR/PDMS, DVB/CAR PDMS). The structure-activity relationship was deeply investigated by the extraction comparison experiment with another similar POF material (PAF-48) and theoretical simulations. The extraction efficiencies of JUC-Z2 for 1-NA and 2-NA are 9.6 and 16.2 times higher than those of PAF-48, and JUC-Z2 has higher binding energies with the aromatic amines than PAF-48. The results indicate that the N atom on the JUZ-Z2 framework played a crucial role for adsorbing aromatic amines. Finally, the novel fiber has been successfully used to detect 1-NA and 2-NA in the urine of smokers.

Developments of solid-phase microextraction fiber coatings for environmental pharmaceutical and personal care products analysis

Abstract Solid-phase microextraction (SPME) is a sample preparation technique with many applications that is being continuously developed. In this technique, the type of fiber coating plays a crucial role for extraction efficiency. Currently available commercial coatings have certain drawbacks that have been overcome by the development of new coatings based on novel materials; these have improved the efficiency of extraction, selectivity and stability of commercial coatings. Pharmaceutical and personal care products (PPCPs) are one of the most important groups of emerging contaminants; however, some studies suggest that these compounds can cause adverse health effects. No official monitoring protocols for these compounds are currently available, so the establishment of analytical methods that allow their determination in environmental samples is required. The complexity of environmental samples together with the low concentration levels of these compounds makes necessary the use of sample preparation techniques capable of removing interferences, as well as preconcentrated analytes, and SPME is a very promising alternative to achieve this. This review describes the recent developments in SPME with classical and novel coatings and its applications for PPCP determination in environmental samples.

A tri-metal centered metal-organic framework for solid-phase microextraction of environmental contaminants with enhanced extraction efficiency

This study presents the preparation and the characterizations of six tri-metal centered metal-organic frameworks (tM-MOFs) as solid-phase microextraction (SPME) adsorbents. Possessing different proportions of Al, Ga and In atoms in their frameworks, the tM-MOF-based SPME coatings exhibited different extraction performance towards the organic pollutants. Extraction results showed that the M4 (Al0.593Ga0.167In0.240(O2C2H4)(h2fipbb)) coating exhibited the best enrichment ability among six tM-MOFs. In addition, it showed better extraction efficiency towards the analytes than three single-metal centered MOFs coatings and a commercial polydimethylsiloxane (PDMS) coating. The adsorption process of the M4 coating was physical adsorption and it was mainly affected by the diffusion process of the compound from the sample to the material, which is the same with the adsorption processes of the single-metal centered MOFs coatings. Under optimal conditions (extraction time, 3 min; NaCl concentration, 25% (w/v); desorption temperature, 270 °C; extraction temperature, 30 °C), the M4 coating achieved low detection limits (0.13–0.88 ng L−1) and good linearity (5–2000 and 5–5000 ng L−1) for benzene series compounds. The repeatabilities (n = 5) for single fiber were between 4.3 and 8.1%, while the reproducibilities (n = 3) of fiber-to-fiber were in the range of 7.9–12.7%. Finally, a M4 coated SPME fiber was successfully applied to the analysis of environmental water samples with satisfactory recoveries (80.8%–119.5%).

Amine-functionalized MIL-53(Al)-coated stainless steel fiber for efficient solid-phase microextraction of synthetic musks and organochlorine pesticides in water samples.

The fiber coating is the key part of the solid-phase microextraction (SPME) technique, and it determines the sensitivity, selectivity, and repeatability of the analytical method. In this work, amine (NH2)-functionalized material of Institute Lavoisier (MIL)-53(Al) nanoparticles were successfully synthesized, characterized, and applied as the SPME fiber coating for efficient sample pretreatment owing to their unique structures and excellent adsorption properties. Under optimized conditions, the NH2-MIL-53(Al)-coated fiber showed good precision, low limits of detection (LODs) [0.025-0.83ngL-1 for synthetic musks (SMs) and 0.051-0.97ngL-1 for organochlorine pesticides (OCPs)], and good linearity. Experimental results showed that the NH2-MIL-53(Al) SPME coating was solvent resistant and thermostable. In addition, the extraction efficiencies of the NH2-MIL-53(Al) coating for SMs and OCPs were higher than those of commercially available SPME fiber coatings such as polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, and polyacrylate. The reasons may be that the analytes are adsorbed on NH2-MIL-53(Al) primarily through π-π interactions, electron donor-electron acceptor interactions, and hydrogen bonds between the analytes and organic linkers of the material. Direct immersion (DI) SPME-gas chromatography-mass spectrometry methods based on NH2-MIL-53(Al) were successfully applied for the analysis of tap and river water samples. The recoveries were 80.3-115% for SMs and 77.4-117% for OCPs. These results indicate that the NH2-MIL-53(Al) coating may be a promising alternative to SPME coatings for the enrichment of SMs and OCPs.

Porous Aromatic Framework 48/Gel Hybrid Material Coated Solid-Phase Microextraction Fiber for the Determination of the Migration of Styrene from Polystyrene Food Contact Materials.

A novel solid-phase microextraction (SPME) fiber was fabricated by a porous aromatic framework 48 (PAF-48)/gel hybrid material through a sol-gel process. PAF-48 is a porous organic framework (POF) material that was polymerized from 1,3,5-triphenylbenzene. The uniform pore structure, high surface area, continuous conjugate network, and hydrophobicity make PAF-48 expected to have special abilities to absorb and extract styrene as well as some other harmful volatile aromatic compounds (VACs). The PAF-48/gel-coated fiber was explored for the extraction of styrene and six VACs (benzene, toluene, ethylbenzene, and xylenes) from aqueous food simulants followed by gas chromatography (GC) separation. The fiber was found to be very sensitive for the determination of the target molecules with wide linear ranges (0.1-200 or 500 μg·kg-1), low limits of detection (LODs, 0.003-0.060 μg·kg-1), acceptable precisions (intraday relative standard deviation, RSD < 5.9%, interday RSD < 7.3%), and long lifetime (>200 times). Particularly for styrene, the PAF-48/gel-coated fiber exhibited a much lower LOD (0.006 μg·kg-1) compared with most of the reported fibers. Moreover, the PAF-48/gel-coated fiber had a high extraction selectivity for styrene and VACs over alcohols, phenols, aromatic amines, and alkanes and show a molecular sieving effect for the different molecule sizes. Finally, the PAF-48/gel-coated SPME fiber was successfully applied in GC for the determination of the specific migrations of styrene and VACs from polystyrene (PS) plastic food contact materials (FCMs).

A novel Schiff base network-1 nanocomposite coated fiber for solid-phase microextraction of phenols from honey samples

A novel covalent organic framework, Schiff base network-1 (SNW-1), was synthesized and used as a solid-phase microextraction (SPME) fiber coating material. The SNW-1 coated SPME fiber was fabricated by a covalent chemical cross-linking between the SNW-1 nanocomposite and a silanol-functionalized stainless steel wire substrate. Scanning electron microscopy and nitrogen isothermal adsorption results indicate that the new fiber coating exhibited a porous, homogenous surface with the Brunauer-Emmett-Teller surface of 668m2g−1. The prepared fiber was explored for the SPME of phenols from honey samples prior to their determination by gas chromatography-mass spectrometry. The developed method had large enrichment factors (136–816), low limits of detection (0.06–0.2ngg−1), good linearity (0.1–100.0ngg−1) and repeatability (<9.7%) for phenols. The recoveries for spiked phenols (1.0ngg−1 and 10.0ngg−1) in Wolfberry, Robinia and Codonopsis honey samples were in the range of 84.2–107.2% with the relative standard deviations ranging from 3.8% to 12.7%. The developed method was suitable for the determination of phenols from honey samples.

Preparation of porous aromatic framework/ionic liquid hybrid composite coated solid-phase microextraction fibers and their application in the determination of organochlorine pesticides combined with GC-ECD detection.

A novel hybrid material incorporating porous aromatic frameworks and an ionic liquid, 1-(triethoxy silyl)propyl-3-aminopropyl imidazole hexafluorophosphate, was prepared as solid-phase microextraction coating and employed for the extraction of organochlorine pesticides. Combining the advantages of porous aromatic frameworks and an ionic liquid, the fiber exhibited a high adsorption capacity for organochlorine pesticides. Under optimized experimental conditions, enhancement factors of 247-1696 were obtained with good linearity in the range of 1-500 μg L(-1). The detection limits and quantification limits were determined to be in the range of 0.11-0.29 μg L(-1) and 0.35-0.93 μg L(-1). The relative standard deviations for six replicates of organochlorine pesticides were in the range of 4.4%-7.2% and 5.7%-10.1% for one fiber and fiber-to-fiber, respectively. By coupling with a gas chromatography-electron capture detector, the novel fiber was successfully used for the determination of organochlorine pesticides in juice and milk samples with recoveries of 76.1%-121.3%.

Sorption of amitriptyline and amphetamine to mixed-mode solid-phase microextraction in different test conditions

A solid-phase microextraction (SPME) method based on a sampler coating that includes strong cation groups (C18/SCX) is explored as a rapid direct sampling tool to detect and quantify freely dissolved basic drugs. Sampling kinetics, sorption isotherms and competitive effects on extraction yields in mixtures were tested for amphetamine and the relatively large/hydrophobic tricyclic antidepressant amitriptyline. Both compounds are >99% ionized at pH 7.4 but their affinity for the C18/SCX fiber is markedly different with distribution coefficients (Dfw values) of 2.49±0.02 for amphetamine and 4.72±0.10 for amitriptyline. Typical changes in electrolyte homeostasis that may occur in biomedical samples were simulated by altering pH and ionic composition (Na+ and K+ concentrations). These changes were shown to affect C18/SCX sorption affinities of the tested drugs with less than 0.2log units. At relatively low fiber loadings (<10mmol/L coating) and at all tested exposure times, linear sorption isotherms were obtained for both compounds but at aqueous concentrations of the individual drugs corresponding to concentrations in blood that are lethal, sorption isotherms became strongly nonlinear. Competition effects within binary mixtures occurred only if combinations of aqueous concentrations resulted in total fiber loadings that were in the nonlinear range of the SPME sorption isotherm for the individual compounds. We also compared sorption to the (prototype) C18/SCX SPME coating with analogue (biocompatible) C18 coated SPME fibers. C18/SCX fibers show increased sorption affinity for cationic compounds compared to C18 fibers, as tested using amitriptyline, amphetamine and trimethoprim. Surprisingly, sorption affinity of these ionized compounds for the C18 SPME fibers were within 1log unit of the C18/SCX SPME fibers. This shows that the strong cation exchange groups within the C18/SCX coating only has a relatively small contribution to the total sorption affinity of cationic compounds. Also the role of negatively charged silanol groups in both the C18 and C18/SCX coating seems small, as anionic diclofenac species sorbed strongly to the C18 fiber. Ionized organic species seem to be substantially adsorbed to the high surface area of C18 in SPME types using porous silica based coatings.

Isoreticular bio-MOF 100-102 coated solid-phase microextraction fibers for fast and sensitive determination of organic pollutants by the pore structure dominated mechanism.

Here we report the successful utilization of the stepwise ligand exchange strategy for the improvement of adsorption ability of a series of bio-MOFs. The fast extraction rate and the different adsorption performances of the three bio-MOF coatings were dominated by their pore structures.

Silica-Based Ionogels: Nanoconfined Ionic Liquid-Rich Fibers for Headspace Solid-Phase Microextraction Coupled with Gas Chromatography–Barrier Discharge Ionization Detection

In this work, hybrid silica-based materials with immobilized ionic liquids (ILs) were prepared by sol-gel technology and evaluated as solid-phase microextraction (SPME) fiber coatings. High loadings of the IL 1-methyl-3-butylimidazolium bis(trifluoromethylsulfonyl)imide ([C4MIM][TFSI]) were confined within the hybrid network. Coatings composition and morphology were evaluated using scanning electron microscopy and energy dispersive X-ray spectrometry. The obtained ionogel SPME fibers exhibited high extractability for aromatic volatile compounds, yielding good sensitivity and precision when combined with a gas chromatograph with barrier ionization discharge (GC-BID) detection. A central composite design was used for assessing the effect of experimental parameters on the extraction process. Under optimized conditions, the proposed ionogel SPME fiber coatings enabled the achievement of excellent enrichment factors (up to 7400). The limits of detection (LODs) were found in the range 0.03-1.27 μg L(-1), whereas the repeatability and fiber-to-fiber reproducibility were 5.6% and 12.0% on average, respectively. Water samples were analyzed by the proposed methodology, showing recovery values in the range of 88.7-113.9%. The results obtained in this work suggest that ionogels can be promising coating materials for future applications of SPME and related sample preparation techniques.

Design and optimization of a total vaporization technique coupled to solid-phase microextraction.

Solid-phase microextraction (SPME) is a popular sampling technique in which chemical compounds are collected with a sorbent-coated fiber and then desorbed into an analytical instrument such as a liquid or gas chromatograph. Typically, this technique is used to sample the headspace above a solid or liquid sample (headspace SPME), or to directly sample a liquid (immersion SPME). However, this work demonstrates an alternative approach where the sample is totally vaporized (total vaporization SPME or TV-SPME) so that analytes partition directly between the vapor phase and the SPME fiber. The implementation of this technique is demonstrated with polydimethylsiloxane-divinylbenzene (PDMS-DVB) and polyacrylate (PA) coated SPME fibers for the collection of nicotine and its metabolite cotinine in chloroform extracts. The most important method parameters were optimized using a central composite design, and this resulted in an optimal extraction temperature (96 °C), extraction time (60 min), and sample volume (120 μL). In this application, large sample volumes up to 210 μL were analyzed using a volatile solvent such as chloroform at elevated temperatures. The sensitivity of TV-SPME is nearly twice that of liquid injection for cotinine and nearly 6 times higher for nicotine. In addition, increased sampling selectivity of TV-SPME permits detection of both nicotine and cotinine in hair as biomarkers of tobacco use where in the past the detection of cotinine has not been achieved by conventional SPME.

Preparation and characterization of metal-organic framework MIL-101(Cr)-coated solid-phase microextraction fiber

Metal-organic frameworks (MOFs) have received great attention as novel sorbents due to their fascinating structures and intriguing potential applications in various fields. In this work, a MIL-101(Cr)-coated solid-phase microextraction (SPME) fiber was fabricated by a simple direct coating method and applied to the determination of volatile compounds (BTEX, benzene, toluene, ethylbenzene, m-xylene and o-xylene) and semi-volatile compounds (PAHs, polycyclic aromatic hydrocarbons) from water samples. The extraction and desorption conditions of headspace SPME (HS-SPME) were optimized. Under the optimized conditions, the established methods exhibited excellent extraction performance. Good precision (<7.7%) and low detection limits (0.32–1.7ngL−1 and 0.12–2.1ngL−1 for BTEX and PAHs, respectively) were achieved. In addition, the MIL-101(Cr)-coated fiber possessed good thermal stability, and the fiber can be reused over 150 times. The fiber was successfully applied to the analysis of BTEX and PAHs in river water by coupling with gas chromatography–mass spectrometry (GC–MS). The analytes at low concentrations (1.7 and 10ngL−1) were detected, and the recoveries obtained with the spiked river water samples were in the range of 80.0–113% and 84.8–106% for BTEX and PAHs, respectively, which demonstrated the applicability of the self-made fiber.

Analysis of volatile components of cape gooseberry (Physalis peruviana L.) grown in Turkey by HS-SPME and GC-MS.

Volatile components in cape gooseberry fruit at ripe stage were collected using headspace-solid phase microextraction, and analyzed by gas chromatography-mass spectrometry. Three solid phase microextraction fiber coatings (DVB/CAR/PDMS, CAR/PDMS, and PDMS/DVB) were tested for evaluation of volatile compounds. DVB/CAR/PDMS fiber showed a strong extraction capacity for volatile compounds and produced the best result in case of total peak areas. A total of 133 volatile compounds were identified in fruit pulp; among them 1-hexanol (6.86%), eucalyptol (6.66%), ethyl butanoate (6.47%), ethyl octanoate (4.01%), ethyl decanoate (3.39%), 4-terpineol (3.27%), and 2-methyl-1-butanol (3.10%) were the major components in the sample extracts.

Preparation of novel alumina nanowire solid-phase microextraction fiber coating for ultra-selective determination of volatile esters and alcohols from complicated food samples

A novel alumina nanowire (ANW) solid-phase microextraction (SPME) fiber coating was prepared by a simple and rapid anodization-chemical etching method for ultra-selective determination of volatile esters and alcohols from complicated food samples. Preparation conditions for ANW SPME fiber coating including corrosion solution concentration and corrosion time were optimized in detail for better surface morphology and higher surface area based on scanning electron microscope (SEM). Under the optimum conditions, homogeneous alumina nanowire structure of ANW SPME fiber coating was achieved with the average thickness of 20μm around. Compared with most of commercial SPME fiber coatings, ANW SPME fiber coatings achieved the higher extraction capacity and special selectivity for volatile esters and alcohols. Finally, an efficient gas sampling technique based on ANW SPME fiber coating as the core was established and successfully applied for the ultra-selective determination of trace volatile esters and alcohols from complicated banana and fermented glutinous rice samples coupled with gas chromatography/mass spectrometry (GC/MS) detection. It was interesting that 25 esters and 2 alcohols among 30 banana volatile organic compounds (VOCs) identified and 4 esters and 7 alcohols among 13 identified VOCs of fermented glutinous rice were selectively sampled by ANW SPME fiber coatings. Furthermore, new analytical methods for the determination of some typical volatile esters and alcohols from banana and fermented glutinous rice samples at specific storage or brewing phases were developed and validated. Good recoveries for banana and fermented glutinous rice samples were achieved in range of 108–115% with relative standard deviations (RSDs) of 2.6–6.7% and 80.0–91.8% with RSDs of 0.3–1.3% (n=3), respectively. This work proposed a novel and efficient gas sampling technique of ANW SPME which was quite suitable for ultra-selectively sampling trace volatile esters and alcohols from complicated food samples.

Preparation of polypyrrole composite solid-phase microextraction fiber coatings by sol–gel technique for the trace analysis of polar biological volatile organic compounds

Two novel polypyrrole (PPy) composite solid-phase microextraction (SPME) fiber coatings involving polypyrrole β-naphthalenesulfonic acid (PPy/β-NSA) and polypyrrole graphene (PPy/GR) composite SPME fiber coatings were prepared by a simple sol-gel technique for selectively sampling relatively polar biological volatile organic compounds (VOCs). Crucial preparation conditions of the PPy composite SPME fiber coatings were optimized and are discussed in detail. Physical tests suggested that the PPy composite SPME fiber coatings possessed a porous surface morphology, stable chemical and thermal properties. Due to the inducing polar functional groups in the PPy molecule, the PPy composite SPME fiber coatings achieved a higher extraction capacity and special selectivity for the polar biological VOCs with conjugate structures, compared with commercial SPME fiber coatings. Enrichment factors of most of the VOCs by the PPy/β-NSA and PPy/GR SPME fibers were much higher than those achieved by common commercially available SPME fiber coatings. Finally, the PPy/β-NSA and PPy/GR SPME fiber coatings were applied for the trace analysis of typical polar VOCs from ant and coriander samples coupled with gas chromatography/mass spectrometry (GC/MS) detection, respectively. It was satisfactory that the average contents of 4-heptanone, 4-heptanol, 4-nonanone and methyl 5-methylsalicylate from ant samples were actually found to be 28.0, 58.7, 3.0 and 0.6 μgg(-1), and the average contents of nonane, decanal, undecanal and dodecanal from coriander samples were actually found to be 0.79, 0.13, 0.06 and 0.21 μgg(-1). The results suggested that PPy composite SPME coatings will be a potentially excellent sampling technique for the trace analysis of polar biological VOCs.

Analyzing freely dissolved concentrations of cationic surfactant utilizing ion-exchange capability of polyacrylate coated solid-phase microextraction fibers

A 7-μm polyacrylate (PA) coated fiber was successfully employed to determine freely dissolved concentrations of cationic surfactants by solid-phase microextraction (SPME) and utilizing the capability of the PA-coating to sorb organic cations via ion-exchange at carboxylic groups. Measured fiber–water partitioning coefficients (Kfw) were constant below a fiber loading of 2mmol per liter polyacrylate, allowing for simple and accurate analysis in a concentration range that is relevant from a risk assessment point of view. Ion-exchange was confirmed to be the main sorption mechanism because of a decreasing Kfw with either higher CaCl2 concentrations or lower pH, and maximum fiber uptake at the polyacrylate cation-exchange capacity (CEC, at 30mmol/L PA). Fiber–water sorption isotherms were established in various aqueous media in toxicological relevant concentrations. The developed SPME method has a high potential for application in ecotoxicological studies, as demonstrated in sorption studies with humic acid in different electrolyte solutions at aqueous concentrations down to the sub nM range. Cationic surfactant sorption affinities for humic acid also depend on medium composition but are orders of magnitude higher than to the PA fiber on a sorbent weight basis.

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

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

Molecularly imprinted polymer coated solid-phase microextraction fiber prepared by surface reversible addition–fragmentation chain transfer polymerization for monitoring of Sudan dyes in chilli tomato sauce and chilli pepper samples

Surface reversible addition-fragmentation chain transfer (RAFT) polymerization method was firstly applied to the preparation of molecularly imprinted polymer (MIP) coated silicon solid-phase microextraction (SPME) fibers. With Sudan I as template, an ultra-thin MIP coating with about 0.55-μm thickness was obtained with homogeneous structure and controlled composition, due to the controllable radical growing and chain propagation in surface RAFT polymerization. The MIP-coated fibers were found with enhanced selectivity coefficients (3.0–6.5) to Sudan I–IV dyes in contrast with those reported in our previous work. Furthermore, the ultra-thin thickness of MIP coating was helpful to the effective elution of template and fast adsorption/desorption kinetics, so only about 18min was needed for MIP-coated SPME operation. The detection limits of 21–55ngL−1 were achieved for four Sudan dyes, when MIP-coated SPME was coupled with liquid chromatography (LC) and mass spectrometry (MS) detection. The MIP-coated SPME–LC–MS/MS method was tested for the monitoring of ultra trace Sudan dyes in spiked chilli tomato sauce and chilli pepper samples, and high enrichment effect, remarkable matrix peaks-removing capability, and consequent high sensitivities were achieved to four Sudan dyes.

Molecularly imprinted polymer coated solid-phase microextraction fibers for determination of Sudan I–IV dyes in hot chili powder and poultry feed samples

In this research, a novel strategy was developed to prepare molecularly imprinted polymer (MIP) coated solid-phase microextraction fibers on a large scale with Sudan I as template and stainless steel fibers as substrate. More than 20 fibers could be obtained in one glass tube, and the efficiency and coating repeatability were enhanced remarkably in contrast with the yield of only one fiber in our previous works. The obtained MIP-coated stainless steel fibers were characterized by homogeneous and highly cross-linked coating, good chemical and thermal stabilities, high extraction capacities, and specific selectivities to Sudan I-IV dyes. Based on the systemic optimization of extraction conditions, a simple and cost-effective method based on the coupling of MIP-coated SPME with high-performance liquid chromatography was developed for the fast and selective determination of trace Sudan I-IV dyes in hot chili powder and poultry feed samples. The limits of detection of Sudan I-IV dyes were within 2.5-4.6 ng g(-1), and the spiked recoveries were in the range of 86.3-96.3% for hot chili powder sample and 84.6-97.4% for poultry feed sample.

Simultaneous sampling and analysis of indoor air infested with Cimex lectularius L. (Hemiptera: Cimicidae) by solid phase microextraction, thin film microextraction and needle trap device

Air in a room infested by Cimex lectularius L. (Hemiptera: Cimicidae) was sampled simultaneously by three different sampling devices including solid phase microextraction (SPME) fiber coatings, thin film microextraction (TFME) devices, and needle trap devices (NTDs) and then analyzed by gas chromatography–mass spectrometry (GC–MS). The main focus of this study was to fully characterize indoor air by identifying compounds extracted by three different microextraction formats and, therefore, perform both the device comparison and more complete characterization of C. lectularius pheromone. The NTD technique was capable of extracting both (E)-2-hexenal and (E)-2-octenal, which were previously identified as alarm pheromones of bedbugs, and superior NTD recoveries for these two components allowed reliable identification based on mass spectral library searching and linear temperature programmed retention index (LTPRI) technique. While the use of DVB/CAR/PDMS SPME fiber coatings provided complementary sample fingerprinting and profiling results, TFME sampling devices provided discriminative extraction coverage toward highly volatile analytes. In addition to two alarm pheromones, relative abundances of all other analytes were recorded for all three devices and aligned across all examined samples, namely, highly infested area, less infested area, and control samples which were characterized by different bedbug populations. The results presented in the current study illustrate comprehensive characterization of infested indoor air samples through the use of three different non-invasive SPME formats and identification of novel components comprising C. lectularius pheromone, therefore, promising future alternatives for use of potential synthetic pheromones for detection of infestations.