Solid-phase Microextraction Fiber Research Articles

Covalent organic framework in situ grown on the metal-organic framework as fiber coating for solid-phase microextraction of polycyclic aromatic hydrocarbons in tea.

A novel MIL-88-NH2@COF composite was produced by in situ growth of covalent organic framework (COF) on the metal-organic framework (MOF) surface. To obtain a coating fiber for solid-phase microextraction (SPME), the MIL-88-NH2@COF composite physically adhered to the stainless steel wire. Combined with gas chromatography-flame ionization detection (GC-FID), various analytes such as chlorophenols (CPs), phthalates (PAEs), and polycyclic aromatic hydrocarbons (PAHs) were extracted and determined to evaluate the extraction performance of MIL-88-NH2@COF coated fibers and explore their extraction mechanism. This composite exhibit excellent extraction performance and adsorption capacity for various analytes, especially for PAHs with enrichment factor up to 9858. The SPME-GC-FID method based on MIL-88-NH2@COF fiber was established for the determination of five PAHs after the main extraction conditions were optimized. Under optimal conditions, the proposed technique showed a wide linear range (1-150ngmL-1) with a low limit of detection (0.019ngmL-1) and a high coefficient of determination (R2 > 0.99). The developed SPME-GC-FID method was used to determine PAHs in green tea and black tea samples, with good recoveries of 51.70-103.64% and 68.56-103.64%, respectively. It is worth mentioning that this is the first time MIL-88-NH2@COF composites have been prepared and applied to SPME. The preparation method of the composite provides a new idea in adsorbent preparation, which will contribute to the field of SPME.

Volatile/semi-volatile metabolites profiling in living vegetables via a novel covalent triazine framework based solid-phase microextraction fiber coupled with GC-QTOF-MS

An in vivo solid-phase microextraction (SPME) fiber with high-coverage capture capacity of plant endogenous substances based on the porous covalent triazine framework (CTF) material was developed. The CTF fiber coupled with gas chromatographic quadrupole time-of-flight mass spectrometer (GC-QTOF-MS) analysis was used for monitoring untargeted endogenous metabolites in living Chinese cabbage plants (Brassica campestris L. ssp. chinensis Makino (var. communis Tsen et Lee)). A total of 100 endogenous substances were identified, mainly including aldehydes, ketones, acids, alcohols, phenols, alkanes, alkenes, esters, isorhodanates, nitriles, as well as indole and its derivatives. Using the in vivo metabolites analysis method, Chinese cabbage plants at different growing stages demonstrated significantly statistical differences in plant metabolism. In addition, metabolic dysregulation of Chinese cabbage plants under fipronil pesticide contamination was observed. To summarize, the proposed approach provides a feasible method to capture metabolic information in living vegetables and for risk assessment of pesticide use during agricultural production.

Nanoporous carbon fiber derived from Cu-BDC metal organic framework @pencil graphite as a sorbent for solid phase microextraction of acetamiprid and imidacloprid

Solid-phase microextraction (SPME) is a sample pretreatment technique for enrichment of trace level of compounds from complex matrices. The fiber coating, as an extraction phase, is the significant part of SPME, which specifying the analytical performance of the developed SPME. In this study, a novel in situ fabricated Cu@porous carbon fiber that derived from copper benzene-1,4-dicarboxylate framework@pencil graphite (Cu-BDC MOF@PG) fiber was prepared as a SPME fiber. The Cu-BDC MOF was electrodeposited on the surface of pencil graphite. The Cu@porous carbon fiber with nanoporous structure was constructed by the direct carbonization of the electrosynthesized fiber.The Cu@porous carbon fiber showed high analytical performance for direct immersion SPME (DI-SPME) of acetamiprid and imidacloprid in fruit and vegetable samples. The SPME method was coupled by high-performance liquid chromatography-ultraviolet detection (SPME-HPLC-UV) for determination of the analytes. Under the optimized condition, good linear ranges (1–500 μg L−1 and 0.5–200 μg L−1) and acceptable limits of detection (LODs = 0.30 and 0.15 μg L−1), appropriate spiking recoveries in the range 87–109.0% were attained for acetamiprid and imidacloprid, respectively. Intra- and inter-day relative standard deviations were found within the ranges of 2.35–3.46% and 3.30–3.70%, respectively. These results signify promising potential of the in situ fabricated porous carbon fiber for SPME applications.Considering that most of the pencil graphite is made of carbon, after the carbonization of the Cu-BDC MOF@PG fiber, a unified porous carbon fiber is obtained. Compared to other reported procedures, in situ direct carbonization of Cu-BDC MOF@PG fiber was a one-step and straightforward method to fabricate carbon fiber.

Metal-Organic Framework ZIF-67@NiCo-LDHs for Extraction of Polycyclic Aromatic Hydrocarbons of Water Sample

In this study, solid-phase microextraction (SPME) fiber adsorbents were coated with the metal-organic framework ZIF-67 and protected by layered double hydroxides (LDH) nanotubes. The findings unequivocally show that the extraction selectivity is dependent on the surface element composition of coatings produced from ZIF-67. The ZIF-67@NiCo-LDHs coating was chosen for the enrichment and detection of polycyclic aromatic hydrocarbons (PAH) in water samples due to its long-term stability and superior extraction selectivity. The calibration curves were dynamically linear and ranged from 0.00 to 100 g L−1 at the optimum circumstances, with correlation values (R 2) above 0.996–0.999. LOD values ranged from 0.07 to 0.5 ng L−1. Under ideal circumstances, the test compounds’’ repeatability for one fiber (n = 3), expressed as relative standard deviation (RSD%), ranged between 7.5 and 9.2%. Additionally, the synthetic fiber displayed 40 cycles of extraction and desorption and perfectly controlled development.

Electrospinning composites of polyvinylidene fluoride - carbon black on solid phase microextraction fibers for enhanced detection of volatile organic compounds by gas chromatography-mass spectrometry

Urine contains volatile organic compounds (VOCs) that can be a source of biomarkers for different medical conditions. Headspace solid phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC–MS) is the gold standard for VOC detection but is time-consuming and expensive. Gas sensors on the other hand are portable and provide rapid results, but qualification of sensing layers is tedious as VOCs need to be tested individually. Our previous study showed that dip coating SPME fibers, using them to extract VOCs from urine and analyzing them by GC–MS is a tool to rapidly characterize sensing elements. The current study aims to extend these findings to demonstrate that HS-SPME GC–MS can identify how electrospinning can enhance the detection of VOCs due to the increased surface area. Herein, previously optimized suspensions of polyvinylidene fluoride-carbon black (PVDF-CB) were deposited on SPME fiber substrates through dip coating and electrospinning, used to extract VOCs from urine and were subject to GC–MS. Electrospinning parameters (applied voltage, flow rate and duration) were optimized, which showed that an applied voltage of 17 kV and a flow rate of 0.25 mL/hr was optimal for electrospinning fibers with 1.5 µm diameter, high coverage and little to no beading. SPME fibers electrospun with PVDF-CB for 10 min were compared to dip coated fibers, and the results showed electrospun fibers had increased efficiency to extract an abundant number of VOCs in urine. These VOCs were enriched when sampled by the electrospun fiber by factors ranging from 1.5 – 5.5. Results also showed that the electrospun fibers had significantly higher reproducibility (p-value < 0.001) relative to dip coated fibers. In summary, electrospinning has the capability of fabricating more sensitive SPME fibers relative to dip coating, and therefore may be utilized in the future for an array of different applications including but not limited to VOC biomarker discovery.

Methods to Detect Volatile Organic Compounds for Breath Biopsy Using Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry.

Volatile organic compounds (VOCs) are byproducts from metabolic pathways that can be detected in exhaled breath and have been reported as biomarkers for different diseases. The gold standard for analysis is gas chromatography-mass spectrometry (GC-MS), which can be coupled with various sampling methods. The current study aims to develop and compare different methods for sampling and preconcentrating VOCs using solid-phase microextraction (SPME). An in-house sampling method, direct-breath SPME (DB-SPME), was developed to directly extract VOCs from breath using a SPME fiber. The method was optimized by exploring different SPME types, the overall exhalation volume, and breath fractionation. DB-SPME was quantitatively compared to two alternative methods involving the collection of breath in a Tedlar bag. In one method, VOCs were directly extracted from the Tedlar bag (Tedlar-SPME) and in the other, the VOCs were cryothermally transferred from the Tedlar bag to a headspace vial (cryotransfer). The methods were verified and quantitatively compared using breath samples (n = 15 for each method respectively) analyzed by GC-MS quadrupole time-of-flight (QTOF) for compounds including but not limited to acetone, isoprene, toluene, limonene, and pinene. The cryotransfer method was the most sensitive, demonstrating the strongest signal for the majority of the VOCs detected in the exhaled breath samples. However, VOCs with low molecular weights, including acetone and isoprene, were detected with the highest sensitivity using the Tedlar-SPME. On the other hand, the DB-SPME was less sensitive, although it was rapid and had the lowest background GC-MS signal. Overall, the three breath-sampling methods can detect a wide variety of VOCs in breath. The cryotransfer method may be optimal when collecting a large number of samples using Tedlar bags, as it allows the long-term storage of VOCs at low temperatures (-80 °C), while Tedlar-SPME may be more effective when targeting relatively small VOCs. The DB-SPME method may be the most efficient when more immediate analyses and results are required.

Carbon nanotubes-assisted solid-phase microextraction for the extraction of gasoline in fire debris samples

Gasoline is one of the most encountered ignitable liquids (IL) in fire debris analysis. The extraction of gasoline from fire debris samples presents challenges due to the complicated nature of multicomponent mixtures. This research work proposed a novel carbon nanotube-assisted solid phase microextraction (CNT-SPME) fiber coupled with gas chromatography and mass spectrometry (GC/MS) to determine gasoline residues for fire debris analysis. The CNT-SPME fiber was prepared by a sequential coating of polydopamine, epoxy, and CNTs on a stainless-steel wire. The extraction capabilities of the CNT-SPME fiber for gasoline and its major aromatic groups (xylenes, alkylbenzenes, indanes, and naphthalenes) from neat and spiked samples were promising, with linear dynamic ranges of 0.4–12.5 and 3.1–12.5 µg 20-mL−1 headspace vial, respectively. The average relative standard deviations and accuracies for all concentration ranges in this work were lower than 15%. The relative recovery of the CNT-SPME fiber for all aromatic groups ranged from 28 ± 3% to 59 ± 2%. Additionally, the CNT-SPME fiber showed a higher selectivity for the naphthalenes group in gasoline, as indicated by the experimental outcome using a pulsed thermal desorption process of the extracts. We envision the nanomaterial-based SPME offers promising opportunities for extracting and detecting other ILs to support fire investigation.

Etched hollow periodic mesoporous organosilica with enlarged pore size for high-performance solid phase microextraction of polybrominated biphenyls

Hollow mesoporous silica has attracted increasing attention due to its outstanding characteristics such as low density, large void, mesoporous channel, and large specific surface area. Herein, a kind of etched hollow periodic mesoporous organosilica (EHPMOS) with enlarged mesopore size was successfully synthesized for high-performance solid phase microextraction (SPME). The etched silica material was prepared as a SPME fiber with uniform morphology, and the enrichment capacities for polybrominated biphenyls (PBBs) were systematically studied. In particular, the EHPMOS showed significant enrichment factors (158–9516) for PBBs. In addition, based on the home-made SPME fiber and gas chromatography-mass spectrometry (GC–MS), an ultra-sensitive analytical method was developed, with low limits of detection (0.11–0.32 ng·L-1), a wide linear range (1–1000 ng·L-1), and satisfactory reproducibility. And accurate quantifications of ultra-trace PBBs in environmental water sample were achieved.

A Study of Headspace Solid-Phase Microextraction in the Analysis of 54 Hydrophobic Pollutants in Remote Alpine Lake Waters with an Emphasis on Analyte Recovery and Storage Time.

Commercially available headspace solid-phase microextraction (HS-SPME) fibers have been used for years to extract pesticides and polychlorinated biphenyls from aqueous samples at the expected ultratrace levels (picograms per liter or parts per quadrillion) in alpine lakes. Several variables of the HS-SPME technique have been adequately evaluated, including water temperature, pH, salt content, fiber type and coating thickness, length of fiber-sample exposure, and liquid immersion versus headspace exposure; but surprisingly, analyte recovery as a function of analyte concentration and storage time has not been included in previous studies, which can be important for remote sampling sites. Seven hydrophobic chlorinated pollutants were identified in alpine lake water (out of 54 analyzed); but recovery using the common SPME technique was found to be inconsistent as the analyte concentration decreases, and the recovery trend as a function of concentration varies on a compound-to-compound basis that could result in a large underestimation of analyte concentrations in field samples. Of the 54 compounds surveyed, o,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-DDT, p,p'-dichlorodiphenyldichloroethylene (DDE), o,p'-DDE, chlorthal-dimethyl, endosulfan I, γ-hexachlorocyclohexane, heptachlor, and trans-nonachlor were generally measured at concentrations between 1 and 150 pg/L (parts per quadrillion). No study to date has evaluated this commonly used but unstandardized technique for analyte recovery as a function of analyte concentration or storage time of aqueous samples. Environ Toxicol Chem 2023;42:1199-1211. © 2023 SETAC.

Zeolitic imidazole framework-67 coated stainless steel fiber for solid-phase microextraction of some alcohols in alcoholic beverage samples

Zeolitic imidazole framework-67 coated stainless steel fiber for solid-phase microextraction of some alcohols in alcoholic beverage samples

Fiber coating based on a green metal-organic framework to determine phthalates in bottled waters by direct-immersion micro solid-phase extraction

The metal-organic framework CIM-80(Al) is proposed as sorbent coating for solid-phase microextraction fibers. The novel CIM-80(Al)-based microextraction fibers (SPME) with a thickness of only 3.5 µm were used to isolate and determine 14 phthalate esters in bottled water with potential results. To compare the extraction efficiency of this novel green material with commercially available SPME fibers, several parameters of the overall procedure were setup. Different parameters such as pH, stirring speed, adsorption and desorption time, salting effect, and percentage of organic solvents were optimized. The results obtained with the CIM-80(Al) based-SPME fibers are promising and comparable to commercial coatings. It demonstrates similar results in a total of 16 bottled water samples subjected to determination. The detection and quantification were performed using ultra-high performance liquid chromatography-tandem mass spectrometer (UHPLC-MS/MS). The effectiveness of the proposed method was corroborated by its analytical characteristics such as limits of detection, which ranged from 0.01 to 0.5 µg L−1 while the linear range was 0.04 to 1 000 µg L−1. In terms of recoveries, CIM-80(Al)-SPME fiber provided results from 70 to 107 %, while the precision of the method in terms of relative standard deviation varied from 1.8 to 18.8 %.

COMPARISON OF DIFFERENT SOLID PHASE MICROEXTRACTION FIBERS IN EXTRACTION OF VOLATILE COMPOUNDS FROM ADIPOSE TISSUE

The volatile compounds (VCs) in headspace of adipose tissues (perirenal, tail, caul) were extracted by solid-phase microextraction (SPME) fiber coated with carboxen/ polydimethylsiloxane (CAR/PDMS) or divinylbenzene/ carboxen/ polydimethylsloxane (DVB/CAR/PDMS). In extraction with CAR/PDMS coating compared to DVB/CAR/PDMS, more VCs were obtained in perirenal (53 versus 41), tail (51 vs 47) and caul (35 vs 33) fats. Increased retention index for aldehydes increased the adsorption on DVB/CAR/PDMS. This fiber also provided a good yield for carboxylic acids. CAR/PDMS fiber could be recommended for VCs from adipose tissues if the goal is to identify aldehydes, especially fatty acid oxidation products and low molecular weight hydrocarbons, as well as greater number of VCs. However, in case of targeting carboxylic acids, esters, and also high molecular weight aldehydes, DVB/CAR/PDMS could be utilized due to its high affinity for mentioned compounds. Furthermore, the optimum extraction time should be studied to determine the time for VCs to reach equilibrium.

Facile Fabrication of Polydopamine-Functionalized Titanium Dioxide Nano/Submicro-Particles on the NiTi Substrate for Highly Efficient Solid-Phase Microextraction of Benzotriazole Ultraviolet Filters from Environmental Water Samples

A new polydopamine-functionalized titanium dioxide nano/submicro-particles (PDA@TiO2NPs) coating was successfully constructed on the surface of NiTi substrate as a solid-phase microextraction (SPME) fiber. To obtain a stable and uniform PDA@TiO2NPs coating, the NiTi fiber was hydrothermally treated for in situ growth of titanium/nickel oxide composite nanosheets (TiNiOCNSs). Subsequently, the titanium dioxide nano/submicro-particles (TiO2NPs) were electrophoretically deposited on the TiNiOCNSs coating. Finally, the polydopamine (PDA) coating was modified on the TiO2NPs coating by self-polymerization of dopamine (DA). Scanning electron microscopy (SEM) of the new PDA@TiO2NPs@TiNiOCNSs@NiTi fiber showed a popcornlike nanostructure with a larger surface area and more adsorption sites. Benefitting from the abundant hydrogen bonding, rich π-electron system, and strong hydrophobicity, the functionalized PDA@TiO2NPs@TiNiOCNSs@NiTi fiber illustrated excellent extraction capability for benzotriazole ultraviolet filters (BUvFs) among typical aromatic compounds coupled to HPLC with UV detection. The main SPME conditions such as extraction and desorption time, extraction temperature, stirring rate, and ionic strength were examined and optimized one by one. Under the optimum conditions, the calibration curves presented good linearity for BUvFs in the ranges from 0.01 µg·L−1 to 300 µg·L−1, and the correlation coefficients (r) were above 0.9990. The limits of detection (LODs, S/N = 3) were between 0.005 µg·L−1 and 0.043 µg·L−1. RSD repeatability of intraday and interday for one fiber was less than 5.3% and 6.9%, respectively. Moreover enrichment factors (EFs) ranged from 63 to 218. The recommended method can completely extract and detect trace BUvFs in different environmental water samples. Furthermore, the new fiber shows good stability and high strength.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (H3PW12O40). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME). The method was used for the extraction of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6- trichlorophenol from tap water, river water, and tea sample. The extracted target analytes were quantified via high-performance liquid chromatography-UV detection. The figures of merit of the method such as, linear dynamic ranges (LDRs), limit of detections (LODs) and, limit of quantifications (LOQs), were determined based on the obtained optimum condition. Based on the results, the LDR was between 1 and 500 μg L − 1 and r2 higher than 0.9960. The LODs and LOQs were obtained in the ranges of 0.28–0.36 µg L − 1 and 0.92–1.1 µg L − 1, respectively. The relative standard deviations ((RSDs% for inter-and intra-day) of the method for the extraction of target analytes were calculated in two different concentrations of (2 and 10 μg L − 1) and (5 and 10 μg L − 1) between 3.70% - 5.30% and 3.50% - 5.70%-respectively. The enrichment factors were obtained between 57 and 61. In order to investigate the accuracy of the method, also the relative recovery was obtained, between 93 and 105%. Finally, the proposed method was used for the extraction of the selected analytes in different water and tea samples.

Characterization of Cooked Nonglutinous Rice Cultivars Based on Flavor Volatiles and Their Change during Storage.

Characterizing fleshly cooked rice cultivars according to the volatile aroma compounds helps consumers select a favorite and is useful for the development of new cultivars that will have a pleasant aroma. In the present study, six Japanese nonglutinous cultivars, which were freshly harvested in 2021, were characterized based on their flavor volatiles after being freshly cooked. In order to extract the volatile compounds just after cooking, the vaporized compounds were extracted for 5 min using a solid-phase microextraction (SPME) fiber and were measured via gas chromatography/mass spectrometry (GC/MS). Multiple comparison tests statistically detected four volatile aroma compounds: 2-pentylfuran, nonanal, 4-vinylphenol, and indole. From among the six rice cultivars tested, the proportions of the latter two compounds showed significant differences, and in principal component analysis of cooked rice, these two best characterized freshly harvested and freshly cooked Japanese nonglutinous rice cultivars; indole was indicative of Nipponbare, and 4-vinylphenol was indicative of Koshihikari and Ichihomare. In the present study, changes in the volatile aroma compounds of the freshly cooked rice cultivars were found to slightly differentiate according to storage times: 2-pentylfuran tended to increase, nonanal first increased and then decreased, and 4-vinylphenol and indole either remained almost unchanged or were only slightly decreased during storage. Therefore, establishing the differences in rice cultivar types revealed that the characteristics of the flavor volatiles of freshly cooked rice after long-term storage significantly depend on how the rice cultivar is stored.

A Zn-based metal coordination cluster Zn5 used for solid phase microextraction of ten phenolic compounds from water and soil

Exploring coating materials with superior extraction efficiency has always been the pursuit in the field of solid phase microextraction (SPME). Metal coordination clusters with high thermal and chemical stability, abundant functional groups as active adsorption site are the promising coatings. In the study, a Zn5(H2Ln)6(NO3)4 (Zn5, H3Ln =(1,2-bis-(benzo[d]imidazol-2-yl)-ethenol) cluster coating was prepared and applied for SPME of ten phenols. Zn5 based SPME fiber exhibited high extraction efficiencies for phenols in headspace (HS) mode, which circumvented the pollution of SPME fiber. The adsorption isotherm and theoretical calculation indicated the adsorption mechanism of phenols on Zn5 was hydrophobic interaction, H-bond interaction and π-π stacking. Under the optimized extraction conditions, an HS-SPME-GC-MS/MS method was developed for the determination of ten phenols in water and soil samples. For ten phenolic compounds in water and soil samples, the linear ranges were 0.5–5000 ng/L and 0.5–250 ng/g, respectively. The limits of detection (LODs, S/N = 3) were 0.010–1.20 ng/L and 0.0048–0.16 ng/g, respectively. The precisions of single fiber and fiber-to-fiber were lower than 9.0% and 14.1%, respectively. The proposed method was applied for the detection of ten phenolic compounds in various water and soil samples, showing satisfactory recovery (72.1–118.8%). This study delivered a novel and efficient SPME coating material for the extraction of phenols.

Selective extraction of fungicides from fruit samples with defective UiO-66 as solid-phase microextraction fiber coating

A defective UiO-66 with rich defect sites was synthesized by a modulator-induced defect formation approach and used as the solid-phase microextraction (SPME) fiber coating material. The extraction experimental results showed that the defective UiO-66 coating can selectively extract the fungicides chlorothalonil, vinclozolin, dimethachlon, procymidone and iprodione with a high adsorption capability. The superior adsorption capability can be attributed to hydrophobic, Lewis acid-base and hydrogen bonding interactions. After optimization, a SPME with the defective UiO-66 as the fiber coating combined with GC–MS detection was established for the sensitive and selective determination of the five fungicides in fruit samples. Under the optimized experimental conditions, the quantitative linear response was in the range of 0.83–300 ng g−1, with the coefficients of determination in the range from 0.9970 to 0.9986 and the limits of detection between 0.25 and 9.0 ng g−1 for the analytes. The method was successfully applied for the determination of the fungicides in different fruit samples. Satisfactory method recoveries (82.7%-117.7%) and good precisions with the relative standard deviations being from 3.2% to 12% were achieved.

Application of poly 3,4-ethylenedioxythiophene and gold nanoparticles composite on a gold wire as a coating for determination of nitroaromatics in soil using cold fiber solid phase microextraction combined with gas chromatography

Although several sensing techniques have been employed for nitroaromatics, developing novel detection approaches for environment analysis is still necessary. In this study, for the first time, the cooling assisted solid phase microextraction (CA-SPME) method was performed using poly 3,4-ethylenedioxythiophene and gold nanoparticles composite coating on a gold wire to extract nitroaromatic compounds. The surface morphology of the homemade SPME fiber was investigated through a field emission scanning electron microscope. The fiber was used to extract 4-nitrotoluene (4-NT), 1,3-dinitrobenzene (1,3-DNB), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) from the soil. To increase extraction efficiency and reduce interferences, extraction was performed from the sample headspace, and the fiber was cooled by a cooling apparatus. Then, the extracts of nitroaromatics were injected into the gas chromatography- flame ionization detector instrument to identify and quantify the analytes. A set of effective experimental parameters in fiber coating characteristics and extraction and separation procedures, including extraction temperature, extraction time, vial volume, and separation conditions in gas chromatography, were optimized. Under optimal conditions, recoveries of nitroaromatics ranged from 96.80% to 102.10%, and the detection limit values were in the range of 0.15 to 0.30 ng.g−1. The linear ranges were obtained to be 0.5–250.0 ng.g−1 and 1.0–250.0 ng.g−1 for 4-NT, 2,4-DNT, 2,6-DNT, and 1,3-DNB, respectively. Finally, the proposed method was successfully tested on real soil samples.

Architectural engineering inspired in situ growth of covalent organic frameworks as outstanding fiber coating for solid-phase microextraction of phenols

The development of a straightforward method for preparing high-performing solid-phase microextraction (SPME) coatings is of paramount importance. In this work, inspired by architectural engineering, a simple and rapid synthetic strategy was developed to grow covalent organic frameworks (COFs) in situ on the surface of stainless steel wire as the SPME coating. Subsequently, the COF-coated fiber was applied for the extraction of phenols. Due to the avoidance of using any binder, the porous structure of COFs was well preserved, leading to a superior extraction performance, surpassing physically adhered COF coatings and commercial polyacrylate coatings. Combined with gas chromatography-mass spectrometry, an efficient and sensitive analytical method for the quantification of phenols was established with high enhancement factors (11080–58762), wide linear ranges (2–10000 ng·L−1), low limits of detection (0.39–0.72 ng·L−1), and good repeatability (RSD, ≤7.9%). Moreover, the feasibility of the established method was demonstrated by the determination of target phenols in certified reference materials (water and soil) with satisfactory results. The proposed in situ preparation method provides a easy and efficient approach to prepare high-performance COF-coated fiber for the efficient SPME of trace phenols from complex matrices in practical samples.

Behavioural Response of Whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) Towards Volatile Organic Compounds Emitted from Eggplant Leaves

The whitefly Bemisia tabaci is considered one of the most destructive insect pests that can attack several vegetable crops worldwide. The behavior of choosing a host plant by whitefly can be significantly influenced by volatile organic compounds. The aim of this investigation is to identify and bioassay the volatile organic compounds emitted from uninfested and infested eggplant leaves with B. tabaci. The current study focuses on the interaction between whitefly and eggplant with the identification of volatile organic compounds emitted from leaves that were collected by headspace solid phase microextraction fiber and gas chromatography mass spectrum analyzed. Both uninfested and infested eggplant leaves released a total of 11 compounds. The amount of volatile organic compounds emitted from affected eggplant leaves by whitefly was higher than from uninfested eggplant leaves. Using a Y-shaped olfactometer bioassay, whitefly preferred to attract toward volatile emitted by eggplant leaves in both uninfested and infested eggplant leaves. Our results suggest these chemical compounds can play a key mediator in host finding behavior. The exploitation of one or more of these compounds can apply in an integrated management program of this pest as a lure in the sticky trap or manipulating insect behavior.