Combination of online hollow fiber liquid phase microextraction with smartphone-based sensing for in situ formaldehyde assay in fabric and wastewater samples.

A miniaturized analytical methodology was introduced based on the combination of a direct and online hollow fiber microextraction method with smartphone color detection. The method was used for the determination of formaldehyde (target analyte) in fabric and wastewater samples. In this regard, two reagents including ammonium acetate buffer and acetylacetone were added to the formaldehyde samples to create a colored compound. The colored compound was extracted from the sample by using the hollow fiber liquid-phase microextraction method, the extracted phase was not taken out of the extraction box and was directly transferred into a specially designed detection cell, and a smartphone was applied for in-situ color sensing and data readout. This combination gathered the advantages of both state-of-the-art microextraction techniques and smartphone sensing. Formaldehyde, as a carcinogenic compound widely used in paint and clothing industries, was selected as a model test. Factors affecting extraction efficiency were investigated and optimized, including the type of organic solvents, reagent concentration, salt, pH, stirring speed, reaction temperature, and extraction time. The linear region of the method under optimal conditions was 40-1500 µg L-1 for wastewater samples and 0.3-11.2 mg kg-1 for fabrics. The limit of detection and limit of qualification were 13 and 40 µg L-1, respectively. The relative standard deviations for concentrations of 100 and 1000 µg L-1 were 6% and 4%, respectively. To evaluate the application of the method for real samples, types of fabric and two samples of oil refinery wastewater were selected. The relative recovery in real samples was 84-98%. The results of the analytical parameters of the method show that the developed method can be used as an efficient method to determine formaldehyde in real samples.

Preparation of a magnetic molecularly imprinted polymer on fibrous silica nanosphere via self-polycondensation for micro solid-phase extraction of chlorpyrifos.

Throughout this research, a new magnetic molecularly imprinted polymer on fibrous silica nanosphere was prepared through self-polycondensation. The selective extraction of chlorpyrifos was performed by the synthesized sorbent and as a determination system, a gas chromatography-electron capture was applied. The formation of sorbent was confirmed through the use of Fourier transform infrared spectroscopy and field emission scanning electron microscopy techniques. The parameters affecting the extraction efficacy of the proposed method were scrutinized in an optimized way. The linear range and the detection limit of the studied method were 0.003-0.3 and 0.001 ng mL-1, respectively. The relative standard deviations were 4.1-5.2 and 5.6-7.6 % for intra- and inter-day (n = 3), respectively. To assess the performance of the proposed method, some water and fruit samples were analyzed and the extraction recoveries of 83-109 % were obtained. These results revealed the method's performance in the analysis of chlorpyrifos in real samples.

Application of boehmite as a fiber coating for headspace solid-phase microextraction of chlorophenols from aqueous samples.

In this paper, the extraction of chlorophenols from water samples was carried out using high surface area boehmite nanoparticles as a sorbent. The surfactant-free process employed to make the nano-boehmite used in this work was simple, green, and efficient. The proposed approach was based on headspace solid-phase microextraction, followed by GC-ECD for the determination of analytes. In situ derivatization of analytes was performed with acetic anhydride in a basic medium. Various effective parameters, including the amount of derivatization reagent, ionic strength, desorption temperature and time, extraction temperature, equilibrium time, and extraction time were studied. Under optimal conditions, the linear dynamic range was 0.05-5.0 µg L-1 for 2,4-dichlorophenol and 2,6-dichlorophenol and 0.003-0.1 µg L-1 for 2,4,6-trichlorophenol. A low limit of detection (0.75 × 10-3-15 × 10-3 µg L-1), and relative standard deviations for real samples (RSDs) <10% were obtained. The precision (as intra- and inter-day RSDs) was between 1.2 and 9.8%. In comparison to commercial fibers (CAR-PDMS, 85 µm), this fiber showed a greater extraction efficiency. Various water samples were subjected to extraction by the proposed method. The recoveries ranged from 90 to 110%.

Development of a colorimetric sensor based on the coupling of a microfluidic paper-based analytical device and headspace microextraction for determination of formaldehyde in textile, milk, and wastewater samples.

A user-friendly, cost-effectively, portable, and environmentally friendly colorimetric sensor for the quantitative determination of formaldehyde was developed based on the combining of microfluidic paper-based analytical device (µPAD), headspace microextraction (HSME), and digital image colorimetry. Coupling HSME and µPAD led to enhancements in selectivity and sensitivity of the sensor through sample cleanup and analyte enrichment. To construct the µPAD-HSME device, two pieces of paper as the sample and detection zone were placed facing each other so that a small common and sealed space was created between them. The color change occurred when the analyte in the gaseous form crossed this gap and reached the detection zone. Colorimetric sensing in the detection zone was performed based on the Hantzsch reaction. The color change in the detection zone was recorded by a smartphone and digital images were processed using image analysis software based on the RGB model. The influence of some key variables on the sensitivity of the method including derivatization reagent composition, sample volume, extraction temperature, and extraction time was studied and optimized. The linear dynamic range of the method was obtained in two ranges of 0.10-0.75 and 0.75-5.0 mg L-1 with a limit of detection of 0.03 mg L-1. The recoveries were in the range 80-126% for the quantification of formaldehyde in textile, milk, and wastewater samples.

Synthesis and characterization of g-C3N4-modified zeolite and its application as a methyl violet 6b cationic dye sorbent.

This paper reports a novel, low-cost, and facile approach to prepare a hybrid material consisting of zeolite, Fe3O4, and graphitic carbon nitride as a sorbent to remove methyl violet 6b (MV) from aqueous solutions. To improve the performance of the zeolite for the removal of MV, graphitic carbon nitride (with different C-N bonds and conjugated π region) was used. Also, to perform an easy and fast separation of sorbent from aqueous media, magnetic nanoparticles were incorporated into the sorbent. The prepared sorbent was characterized by different analytical techniques such as X-ray diffraction analysis, Fourier transform infrared, field emission scanning electron microscopy, and energy-dispersive X-ray analysis. The effects of four parameters of initial pH, initial concentration of MV, contact time, and the adsorbent amount on the removal process were investigated and optimized by the central composite design method. The removal efficiency of MV was modeled as a function of the experimental parameters. Affording to the proposed model, the values of 10 mg, 28 mg L-1, and 2 min were selected as optimum condition for adsorbent amount, initial concentration, and contact time, respectively. Under this condition, the optimal removal efficiency was 86% ± 2.8 which were close to the predicted value of the model (89%). Therefore, the model could fit and predict the data. The maximal adsorption capacity of sorbent derived from Langmuir's isotherm was 384.6 mg g-1. The applied composite can efficiently remove MV from various wastewater samples (paint, textile industries, pesticide production wastewater samples, and municipal wastewater).

Evaluating cottonwood seeds as a low-cost biosorbent for crystal violet removal from aqueous matrics.

In this study, cottonwood seeds (CWS) were introduced as a novel, green, and low-cost biosorbents for the removal of crystal violet (CV) dye from aqueous solutions. To illustrate the characteristics of CWS, surface morphology, Fourier-transform infrared spectroscopy, field emission scanning electron microscopes, and energy dispersive X-ray spectroscopy techniques were employed. Important adsorption variables (i.e., equilibrium time, solution pH, CWS amount, CV concentration, and temperature) were systematically studied. Maximum CV dye adsorption was observed at pH 10 using 20 mg of the adsorbent. Different adsorption isotherms were investigated, and the results were more accurately consistent with the Langmuir model (R2 = 0.992). The maximum capacity of adsorption was 153.85 mg g-1 at 60 min. The kinetic data were examined by different models and a pseudo-second-order model supplied the best correlation between experimental data. Investigated thermodynamic parameters at different temperatures illustrated that the CV adsorption procedure was spontaneous and endothermic with an increase in entropy. The percentage removal and the relative standard deviations for the real sample analysis were in the range of 89-98% and 4.9-9.5%, respectively. High adsorption capacity and low equilibrium time demonstrated that CWS is an impressive biosorbent for dye pollutants uptakes from aqueous solutions and real industrial wastewater samples.

A novel, green, available, and low-cost cottonwood seeds were introduced for the removal of crystal violet from aqueous media. In terms of adsorption capacity and contact time, cottonwood seeds show excellent performance compared to the other low-cost biosorbents previously reported for the adsorption of the organic dye from wastewater. The use of cottonwood seeds to remove environmental pollutants has not been introduced yet.

Silica aerogel modified electrospun polyacrylonitrile as a sorbent for thin-film microextraction of chlorpyrifos from real samples coupled with corona discharge ion mobility spectrometry detection.

In this paper, modified polyacrylonitrile/silica aerogel fibers were prepared and used as an adsorbent for thin-film microextraction of chlorpyrifos. The extracted analyte was analyzed by corona discharge ion mobility spectrometry. The electrospinning method was applied for the preparation of polyacrylonitrile fibers. The alkaline hydrolyzation technique was used to modify the electrospun film surface. Silica aerogel was synthesized on the surface of modified electrospun polyacrylonitrile fibers by the in situ growth technique. To access a high extraction yield, effective synthesis and extraction parameters such as NaOH concentration, reaction temperature and time, thin-film pretreatment, gelation time, solution pH, ionic strength, and extraction time were studied. The linearity range and the limit of detection of the method were 1-100 µg L-1 and 0.3 µg L-1, respectively. The precision of the method was 4 and 12% for the concentration levels of 5 and 60 µg L-1, respectively. Chlorpyrifos was successfully determined by the method in well water, river water, agricultural wastewater, and tangerine samples.

A green microfluidic method based liquid phase microextraction for the determination of parabens in human urine samples.

Development of green approaches have emerged as a challenge that highlight the pressing need for nontoxic solvents, miniaturized method and bio-degradable materials. In this regard, an environmentally-friendly microfluidic system based on natural deep eutectic solvents (DESs) immobilized in agarose membranes was developed to extract parabens from urine samples for the first time. A comprehensive study of the support liquid membrane showed that only 3 µL of camphor and thymol (2:1 molar ratio) was an interesting option as a substitute for conventional (toxic) solvents used to date. Other experimental conditions were optimized and pH 4 (HCl) and 12 (NaOH) were selected as sample and acceptor solution, respectively. Both solutions (sample and acceptor) were fixed at 1 µL min-1 as flow rate. The proposed green microfluidic device was successfully applied for the determination of parabens in urine samples with relative recoveries between 86 and 100% for all analytes. Detection limits and quantitation limits were between 0.011-0.093 and 0.31-0.38 µg mL-1, respectively. Relative standard deviation was below 7% for all analytes. Furthermore, the environmentally-friendly solvent (Ca:Ty 2:1) used as SLM offered the same advantages in terms of membrane stability allowing consecutive extractions. Results were compared with experiments previously conducted using conventional (polypropylene) membranes, observing that highly green microextraction systems based on natural and biodegradable materials have proven to be an attractive alternative in microfluidic systems.

Sponge-like porous manganese(II, III) oxide as a coating for solvent-assisted solid-phase microextraction of polycyclic aromatic hydrocarbons followed by gas chromatography-mass spectrometry.

A nanostructure sponge-like porous manganese(II, III) oxide was synthesized and applied as a new fiber coating for solvent-assisted solid-phase microextraction. The synthesized material was characterized via Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and N2 adsorption/desorption techniques. To investigate the extraction performance of the prepared material, direct immersion solid-phase microextraction followed by gas chromatography-mass spectrometry was used for the determination of the selected polycyclic aromatic hydrocarbons in wastewater samples. Three polycyclic aromatic hydrocarbons including 1-methylnaphthalene, anthracene, and pyrene were selected as model analytes. To maximize the sensitivity of the method, key experimental factors affecting the extraction efficiency of the analytes such as ionic strength, extraction solvent, stirring rate, extraction temperature and time, and desorption temperature and time were optimized. The applicability of the new coating material for the extraction of the selected analytes from wastewater samples was evaluated. Under the optimum conditions, detection limits between 0.7 and 1.5 ng L-1 were obtained for the model analytes. The linear dynamic range was 5.0-3.0 × 103 ng L-1 for all the analytes. Relative standard deviations were between 2 and 11%. In the case of real sample analysis, the extraction recoveries of the analytes were obtained in the range of 77-111%.

Microfluidic liquid-phase microextraction based on natural deep eutectic solvents immobilized in agarose membranes.

In liquid-phase microextraction (LPME), the sample and the acceptor are separated by a synthetic organic solvent, which is immobilized in a porous polymeric membrane of polypropylene or polyvinylidene fluoride. The organic solvent serves as extraction phase, while the polymeric membrane serves as support membrane. The combination of extraction phase and support membrane is termed supported liquid membrane (SLM). In this paper, we developed for the first time fully green and biodegradable supported SLMs, based on natural deep eutectic solvents as extraction phase and agarose as support membrane. This highly green approach was developed and studied with sulfonamide pharmaceuticals as model analytes, and performance was compared with LPME using conventional SLMs. All experiments were conducted in a microfluidic device. Model analytes were extracted from acidic sample (pH1.0) and into alkaline acceptor (pH12.0). Both sample and acceptor were pumped at 1 µL min-1 into the microfluidic device, and the optimal SLM was based on 3 µL of coumarin and thymol (1:2 molar ratio) as the extraction phase. The proposed green microfluidic device was successfully applied for the determination of sulfonamides in urine samples with spiking recoveries in the range of 77-100%. LPME with deep eutectic solvent immobilized in agarose showed similar performance as with conventional SLMs. Thus, the data presented in this paper demonstrate that highly green microextraction systems may be developed in the future, based on natural solvents and biodegradable materials.

A microchip device based liquid-liquid-solid microextraction for the determination of permethrin and cypermethrin in water samples.

In this work, for the first time, a microchip device integrating liquid-liquid-solid phase microextraction is presented. As a novel approach to microchip systems, liquid-liquid-solid microextraction was performed in a sandwiched microchip device. The microchip device consisted of three poly(methyl methacrylate) layers along with a double "Y"-shaped microchannel. As the stationary phase, polyacrylonitrile-C18 was synthesized and immobilized in the upper channel, while the beneath channel was used as a reservoir for the stagnant volume ratio of sample-to-extraction solvent phase. In this way, analytes were extracted from an aqueous sample through an organic phase into the stationary phase. The analytes were finally desorbed with a minimum amount of acetonitrile as the desorption solvent. Permethrin and cypermethrin were selected as the model analytes for extraction and subsequent analysis by gas chromatography-flame ionization detection. Under optimum conditions (extraction solvent; n-hexane, sample -to-extraction solvent volume ratio; 2:1, extraction time; 20 min, desorption solvent; acetonitrile, desorption volume; 200 µL, and desorption time; 15 min) detection limits were 3.5 and 6.0 ng mL-1 for permethrin and cypermethrin, respectively. Relative standard deviations for intra- and inter-day reproducibility were below 8.3%. Device-to-device precision was in the range of 8.1-9.6%. The proposed microchip device was successfully applied to determine permethrin and cypermethrin in water samples with recoveries in the range of 73-96%.

A selective and efficient microfluidic method-based liquid phase microextraction for the determination of sulfonamides in urine samples.

Liquid phase microextraction (LPME) into a microfluidic has undergone great advances focused on downscaled and miniaturized devices. In this work, a microfluidic device was developed for the extraction of sulfonamides in order to accelerate the mass transfer and passive diffusion of the analytes from the donor phase to the acceptor phase. The subsequent analysis was carried out by high performance liquid chromatography with UV-DAD (HPLC-DAD). Several parameters affecting the extraction efficiency of the method such as the supported liquid membrane, composition of donor and acceptor phase and flow rate were investigated and optimized. Tributyl phosphate was found to be a good supported liquid membrane which confers not only great affinity for analytes but also long-term stability, allowing more than 20 consecutive extractions without carry over effect. Under optimum conditions, extraction efficiencies were over 96 % for all sulfonamides after 10 minutes extraction and only 10 µL of sample was required. Relative standard deviation was between 3-5 % for all compounds. Method detection limits were 45, 57, 54 and 33 ng mL-1 for sulfadiazine (SDI), sulfamerazine (SMR), sulfamethazine (SMT) and sulfamethoxazole (SMX), respectively. Quantitation limits were 0.15, 0.19, 0.18 and 0.11 µg mL-1 for SDI, SMR, SMT SMX, respectively. The proposed microfluidic device was successfully applied for the determination of sulfonamides in urine samples with extraction efficiencies within the range of 86-106 %. The proposed method improves the procedures proposed to date for the determination of sulfonamides in terms of efficiency, reduction of the sample volume and extraction time.

In situ growth of copper-based metal-organic framework on a helical shape copper wire as a sorbent in stir-bar sorptive extraction of fenthion followed by corona discharge ion mobility spectrometry.

In this paper, a helical copper wire, coated with copper-benzene-1,4-dicarboxylic acid metal-organic framework (Cu-BDC) was used as a sorbent for stir-bar sorptive extraction of fenthion from water and fruit samples. The homogenous coating was fabricated through two simple and fast steps. The chemical conversion of copper substrate to copper hydroxide nanotubes (Cu(OH)2 NTs) was performed in an alkaline solution and then Cu-BDC was formed through a neutralization reaction. Corona discharge ion mobility spectrometry in positive mode was applied for the detection of fenthion. To improve the sensitivity of the method, some synthesis and extraction parameters affecting the extraction efficiency such as benzene-1,4-dicarboxylic acid concentration, ionic strength, sample pH, stirring rate, extraction temperature, and extraction time were investigated. The linear dynamic range between 0.5 and 80 µg L-1 and detection limit of 0.1 µg L-1 were obtained under optimal conditions. The intra- and inter-day relative standard deviations were less than 6.4 and 8.6%, respectively. The applicability of the method was examined for the analysis of different samples (i.e., well water, agricultural wastewater, and orange). The recovery for the determination of fenthion in spiked samples varied from 88 to 111%.

Self-rotating stir mesh screen sorptive extraction for analyzing chlorpyrifos by ion mobility spectrometry.

A mesh screen was electrochemically coated with polypyrrole and used as a sorptive extractor device, for the first time. This configuration acts in such a way that it is self-rotating in the presence of a magnetic force and can be used for extraction and concentration of analytes. Actually, applying a mesh screen instead of a bar or plate in sorptive extraction provided a more effective contact area between the sorptive materials and sample solution, resulting in higher sorption efficiency. The device performance was assessed by using chlorpyrifos pesticide as a model analyte. A thermal desorption unit was coupled to an ion mobility spectrometer and applied for evaporating the extracted analyte. Different parameters affecting the extraction efficiency during the electro-polymerization and the extraction process, including the time of electrodeposition, the concentration of pyrrole, oxalic acid and salt, temperature and time of extraction, and the stirring rate of the extractor device were investigated and optimized, simultaneously. The detection and quantification limits of the method were calculated to be 0.035 and 0.1 µg L-1, respectively. The linear dynamic range obtained was from 0.1 to 20 µg L-1, with a determination coefficient of 0.9984. The intra-day and inter-day-relative standard deviations (RSD, n = 3) were lower than 3% and 8%, respectively. Under the optimal conditions, the absolute recovery and the enrichment factor were found to be 97% and 5820, respectively. Finally, the relative recoveries of the proposed method were calculated to be in the range of 86-111% for spiked water, wastewater, and apple samples. The results obtained from the method were validated by EPA method 622.

A novel nanocomposite based on covalent organic polymer and nanocellulose for thin-film microextraction of imipramine from biological samples.

A novel covalent organic polymer was prepared using 1,5-diaminonaphthalene as a linker and cyanuric chloride as a node. A thin-film nanocomposite of 1,5-diaminonaphthalene covalent organic polymer and cellulose nanocrystalline was then fabricated via filtering and casting method. The effect of incorporation of various amounts of 1,5-diaminonaphthalene covalent organic polymer and cellulose nanocrystalline was studied to obtain an efficient nanocomposite thin-film with a large number of polar functional groups and high mechanical stability. Field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, and thermogravimetric analysis techniques were applied for the characterization of physicochemical properties of the prepared materials. Imipramine was determined in the biological samples using thin-film microextraction followed by gas chromatography flame ionization detection. Parameters affecting the extraction efficiency of imipramine were investigated. Under the optimized conditions, the limit of detection was 0.5 ng/mL. Film-to-film reproducibility for three different films fabricated under the same conditions (at three concentration levels) varied between 8.9 and 9.7%. The linear dynamic range covered more than three orders of magnitude (2-5000 ng/mL) with a determination coefficient of 0.9985. The method was successfully applied for preconcentration and determination of imipramine in biological samples with spiking recoveries between 78 and 93%.

A molecularly imprinted polymer on chromium (ΙΙΙ) oxide nanoparticles for spectrofluorometric detection of bisphenol A.

A unique fluorescent probe for the detection of bisphenol A (BPA) was established by creating a molecularly imprinted polymer (MIP) shell on chromium (ΙΙΙ) oxide nanoparticles (Cr2O3 NPs). The advantages of high selectivity of MIPs and the strong fluorescence property of Cr2O3 NPs were combined for the preparation of the probe. MIPs-coated Cr2O3 NPs were composed by anchoring MIP layer on the surface of Cr2O3 NPs using one-pot precipitation polymerization. Acrylic-based monomer and cross-linker were used to prepared MIP. The MIP-coated Cr2O3 NPs were characterized by spectrofluorometery, Fourier transform infrared spectroscopy, transmission electron microscopy, field transmission electron microscopy, dynamic light scattering, EDX and elemental mapping. The prepared NPs showed strong fluorescence emission at 360 nm excited at 300 nm which quenched in the presence of BPA. The dynamic range of the optical sensor was in the range of 0.04-4.4 µmol L-1 and the detection limit was 0.015 µmol L-1. The relative standard deviation was 2.2 and 1.3% for the concentration levels of 0.14 and 3.1 µmol L-1, respectively. The probe had a great selectivity in the determination of BPA with an imprinting factor of 6.3. The sensor was applied for the quantification of bisphenol A in water samples.

Electroanalytical Sensor Based on Gold-Nanoparticle-Decorated Paper for Sensitive Detection of Copper Ions in Sweat and Serum.

The growth of (bio)sensors in analytical chemistry is mainly attributable to the development of affordable, effective, portable, and user-friendly analytical tools. In the field of sensors, paper-based devices are gaining a relevant position for their outstanding features including foldability, ease of use, and instrument-free microfluidics. Herein, a multifarious use of filter paper to detect copper ions in bodily fluids is reported by exploiting this eco-friendly material to (i) synthesize AuNPs without the use of reductants and/or external stimuli, (ii) print the electrodes, (iii) load the reagents for the assay, (iv) filter the gross impurities, and (v) preconcentrate the target analyte. Copper ions were detected down to 3 ppb with a linearity up to 400 ppb in standard solutions. The applicability in biological matrices, namely, sweat and serum, was demonstrated by recovery studies and by analyzing these biofluids with the paper-based platform and the reference method (atomic absorption spectroscopy), demonstrating satisfactory accuracy of the novel eco-designed analytical tool.

Centrifuge-free dispersive liquid-liquid microextraction coupled with thin-film microextraction for the preconcentration of molinate in real samples by ion mobility spectrometry.

A tandem microextraction method, centrifuge free dispersive liquid-liquid microextraction and thin-film microextraction (DLLME-TFME), was used for analyzing molinate in environmental samples by ion mobility spectrometry (IMS). Considering the IMS as a competitive detection system, coupling these two popular sample preparation methods reduces the effect of solvent interference and improves the sensitivity of the technique. Trichloromethane and methanol were used as the extraction, and dispersive solvents for the DLLME method and electrospun polyacrylonitrile/copper-benzene-1,4-dicarboxylic acid fibers were used as a sorbent in the TFME method. Some effective experimental variables influencing the extraction efficiency of an analyte such as type and volume of dispersive and extraction solvents, solution pH, ionic strength, sonication time, and extraction time were studied. The linear dynamic range of 0.5-50 µg L-1 and the limit of detection of 0.1 µg L-1 were obtained under optimized conditions. The relative standard deviations for intra-and inter-day analysis were calculated less than 10%. The present method was used for the determination of molinate in different real samples such as agricultural wastewater, well water, river water, and apple, and the recovery was obtained between 82% and 113%, for the spiked samples.

Covalent triazine-based framework-grafted functionalized fibrous silica sphere as a solid-phase microextraction coating for simultaneous determination of fenthion and chlorpyrifos by ion mobility spectrometry.

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).

Preparation of kapa carrageenan-based acidic heterogeneous catalyst for conversion of sugars to high-value added materials.

A novel composite based on kappa-Carrageenan (κC) was prepared using N,N-methylene bisacrylamide (MBA) as the crosslinking agent. 5-Hydroxymethylfurfural (5-HMF) was produced by catalytic dehydration of fructose and glucose with MBA grafted κC (κC-g-MBA) as the solid acid catalyst due to sulfonic acid groups in biopolymer skeletons. Various reaction parameters such as optimization of the quantity of the catalyst, temperature, reaction time, and solvent were performed. It was established that for fructose dehydration, the best reaction conditions were the 160 °C as the optimized reaction temperature and 1 h reaction time, respectively. Under these conditions, the HMF yield and fructose conversion were 94.2% and 95.5%, respectively. Furthermore, 160 °C and 2 h were the best reaction temperature and reaction time for glucose dehydration, respectively. Under similar conditions, the HMF yield and glucose conversion are 47% and 93%, respectively. The catalyst was readily prepared from inexpensive materials with considerable reusability and reactivity.