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A novel covalent triazine-based framework (CTF)-grafted phenyl-functionalized fibrous silica nanosphere, KCC-1 (named as RS-2) was synthesized via a simple and effective Friedel-Crafts approach. The microporous CTF with fluorene backbone was coupled and grown uniformly on the surface of phenyl-functionalized KCC-1 to prepare a hybrid extended porous framework. The prepared materials were characterized, and FE-SEM and TEM images revealed a flower-like structure for RS-2. The synthesized RS-2 showed excellent thermal stability, so the weight loss was about 30% at 800 °C. RS-2 was applied as a new coating in the solid-phase microextraction procedure to extract chlorpyrifos and fenthion pesticides from water, wastewater, and fruit samples, before determining by corona discharge-ion mobility spectrometry. Some experimental factors affecting the extraction yield of the analytes, including ionic strength, stirring rate, sample pH, extraction temperature, and extraction time, were investigated. Under optimum conditions, the linear dynamic ranges were 0.1-10 μg L -1 and 1.0-70 μg L -1 , and the limits of detection were 0.05 and 0.55 μg L -1 for chlorpyrifos and fenthion, respectively. The proposed method showed recovery values in the range 86-117% with a precision of 3.0-7.1% for real samples. Covalent triazine-based framework (CTF)-grafted phenyl-functionalized fibrous silica nanosphere (named as RS-2) was synthesized. RS-2 was applied as a sorbent for solid-phase microextraction (SPME) of chlorpyrifos and fenthion from fruit and water samples followed by corona discharge ionization ion mobility spectrometry (CD-IMS).

A biomass-derived sponge-like carbonaceous aerogel was prepared through a two-step procedure, including hydrothermal carbonization and freeze-drying process. The aerogel was employed as the solvent holder for liquid-phase microextraction of organophosphorus pesticides, ethion, and chlorpyrifos (as the model compounds), prior to determination by secondary electrospray ionization-ion mobility spectrometry. The carbonaceous aerogel is an appropriate candidate to be used as the solvent holder due to some properties such as three-dimensional structure, porous nature, and very low density. So, the aerogel, including extraction solvent, can tumble on the top of the sample solution, without loss of solvent during its agitation. A comparison of the extraction efficiency was performed at similar conditions between the proposed method and single-drop microextraction, as well as hollow-fiber solvent bar microextraction. Different parameters affecting the extraction efficiency, such as stirring rate, salt concentration, temperature, and extraction time were investigated by using the response surface methodology. The linear dynamic range was in the ranges 1-30 and 1-70 μg L -1 with regression coefficients of 0.9973 and 0.9956 for ethion and chlorpyrifos, respectively. The limit of detection was 0.09 and 0.21 μg L -1 for ethion and chlorpyrifos, respectively. The method was used for extracting analytes from environmental water and vegetable samples, with the spiking recoveries in the range 80-121%. Graphical abstract Schematic representation of three-dimensional biomass-derived carbonaceous aerogel as the solvent holder in solvent bar microextraction (as a mode of the liquid-phase microextraction method). It was used for the extraction of two kinds of organophosphorus pesticides prior to the determination by ion mobility spectrometry.

Molecularly imprinted-electrospun nanofibers based on the use of poly(vinyl alcohol) were fabricated and used as a new sorbent for solid-phase microextraction of chlorpyrifos. The molecularly imprinted nanofibers were prepared by electrospinning and direct molecular imprinting of polymeric nanofibers. Poly(vinyl alcohol) was used as the functional and electrospun polymer. Chlorpyrifos was used as a template molecule, and glutaraldehyde as the cross-linker. Detection was performed by ion mobility spectrometry equipped with a secondary electrospray ionization source. The molecularly imprinted fiber has a selectivity and extraction efficiency better than the fiber fabricated using the conventional method of encapsulating MIP particles in electrospun nanofibers. Parameters affecting the extraction efficiency such as ionic strength, stirring rate, extraction time, and temperature were evaluated. The dynamic range of the method was in the range of 0.5-200 μg L -1 with the limit of detection of 0.1 μg L -1 . The intra- and inter-day relative standard deviations of the method were 4 and 9%, respectively. The fiber-to-fiber reproducibility for three different fibers is 5%. The spiking recoveries from spiked apple, cucumber, and water samples were in the range of 82-112%. Graphical abstract Molecularly imprinted-electrospun nanofibers were fabricated based on the direct molecular imprinting technique and used as a new SPME fiber coating for selective extraction of chlorpyrifos from fruits and water samples prior its determination by secondary electrospray ionization-ion mobility spectrometry.

A porous graphite sheet modified by a molecularly imprinted polymer (MIP) was directly used as the spray ionization source for ion mobility spectrometry (IMS). Therefore, it was possible to selectively analyze samples extracted by the molecularly imprinted polymer. This obviates the need for the steps of elution, solvent evaporation, dissolution and injection. To prepare the sheet, the graphite surface was first modified by electrodeposition of a molecularly imprinted polypyrrole film. This polypyrrole film was fabricated in a three-electrode electrochemical system using cyclic voltammetry. The electropolymerization of the graphite sheet was carried out with LiClO 4 as a supporting electrolyte in the reaction solution. The effects of the amount of monomer, the level of template concentrations, and the time of polymerization on the extraction efficiency of the MIP film were evaluated. The extraction conditions including extraction time, the extraction temperature, the pH values, the salt concentrations, and the stirring rate were also studied. Methanol was selected as the most suitable solvent for both desorption and ionization which occur simultaneously. The pesticide propoxur (acting as a test compound) was extracted from water samples and directly analyzed using IMS. The analytical parameters (working range: 1.0 to 250 ng·mL -1 ; detection limit: 0.3 ng·mL -1 ) indicated that the direct coupling of MIP and IMS has a great potential in terms of reproducibility, and speed of the analysis, while maintaining acceptable sensitivity. Graphical abstract Schematic presentation of molecularly imprinted graphite spray ionization coupled with ion mobility spectrometry (IMS) for rapid/selective extraction and ionization: Application to the pre-concentration of propoxur prior to its quantification by IMS.

Carbon sheets were attached to magnetite (Fe 3 O 4 ) nanoparticles. The resulting nanocomposite is shown to be a viable sorbent for use in magnetic dispersive solid-phase microextraction of three organophosphorus pesticides. The sorbent was synthesized via the sol-gel process followed by calcination and was characterized by an X-ray diffractometer, field emission scanning electron microscopy and energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and Raman spectrometry techniques. The affecting parameters in the adsorption and desorption steps were assessed and optimized via response surface methodology. Following desorption with dichloromethane, the OPPs were quantified by gas chromatography along with ion mobility spectrometry detection. Under optimized conditions, the limits of detection were 1.00, 0.46 and 0.85 μg L -1 for fenthion, malathion and chlorpyrifos, respectively. Response is linear in the concentration range of 2-500 μg L -1 for fenthion and malathion, and 2-1000 μg L -1 for chlorpyrifos with the determination coefficient larger than 0.9969. The intra-day and inter-day precision were from 3 to 9% and 5 to 16%, respectively. The enrichment factor was greater than 142 for all the studied pesticides. The sorbent was used for analyze spiked water and vegetable samples and gave relative recovery higher than 82%. Graphical abstract A flowchart of the synthesis of porous magnetized carbon sheet nanocomposites and the process of the magnetic dispersive solid-phase microextraction (MD-μ-SPE) of three organophosphorus pesticides prior to analysis by gas chromatography-ion mobility spectrometry (GC-IMS).

Thin film nanofibers containing ZnTiO 3 nanoparticles were used for rapid and efficient evaporation of solvents as used to extract analytes by dispersive liquid-liquid microextraction (DLLME). The method is referred to as thin film evaporation (TFE). A combination of DLLME and TFE was applied to the extraction and preconcentration of the pesticide chlorpyrifos (as a model compound) prior to analysis by ion mobility spectrometry. The ZnTiO 3 nanoparticles were placed on polyacrylonitrile nanofibers which increases the porosity and surface area in the TFE process, thus causing fast and complete evaporation of solvents. The effects of sample pH value, extraction solvent and its volume, disperser solvent and volume, centrifugation time, evaporation time, and desorption temperature were optimized. The relative standard deviations of intra- and inter-day analyses were found to be 3% and 7%, respectively. The method has a linear dynamic range that covers the 0.10-3.0 μg.L -1 chlorpyrifos concentration range, the limit of detection is 0.04 μg.L -1 , and the enrichment factor is up to 5400 in case of spiked samples. Some spiked field samples were analyzed and the relative recoveries ranged between 99 and 111%. When applied along with ion mobility spectrometry, the interferences caused by solvent are found to be reduced in the ionization source. This makes it possible to select a variety of solvents as needed for sample extraction. Graphical abstract Schematic presentation of dispersive liquid-liquid microextraction (DLLME) combined with thin film evaporation (TFE) for rapid vaporization of extraction solvent: Application to the pre-concentration of chlorpyrifos prior to its quantification by corona discharge-ion mobility spectrometry (CD-IMS).

A cellulose paper was modified with an aptamer against methamphetamine on either carbon dots (CDs) or on multichannel carbon nanotubes (CNTs). The resulting sorbent was applied to the extraction of METH from blood or saliva. The METH-loaded paper than also was directly applied as a paper spray ionization source in ion mobility spectrometry. The carbon nanomaterial enhances sensitivity, and the aptamer enhances selectivity. The materials were covalently bound to the paper on one side, while the aptamer was immobilized on the other. After optimization of the extraction process and instrumental parameters, the limits of detection when using the aptamer-CNT modified paper are 0.6 ng·mL -1 for saliva, and 0.45 ng·mL -1 for plasma. The respective values when using aptamer-CD modified paper are 1.5 ng·mL -1 for saliva and 0.9 ng·mL -1 for plasma. Calibration plots are linear in the 2 to 150 ng·mL -1 METH concentration range for saliva, and in the 1.5 to 200 ng·mL -1 concentration ranges for blood when using the aptamer-CNT based method. When using the aptamer-CDs, the dynamic ranges extend from 5 to 200 ng·mL -1 and from 3 to 250 ng·mL -1 , respectively. The method was applied to the determination of METH in real samples of saliva and blood, and the accuracy of the method was confirmed by comparison of the results with data analyzed by GC-MS. Graphical abstract ᅟ.