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Drastically improved adsorption capacity for ethopabate is achieved by the partial carbonization of ZIF-8.

Electrospun g-C3N5/MIL-101(Fe)/poly(acrylonitrile-co-maleic acid) nanofibers were fabricated for the highly efficient degradation of emerging pharmaceutical pollutants.

In this study, reduced graphene oxide (rGO) hybridized high internal phase emulsions were developed and polymerized as porous carriers for aptamer (5’/5AmMC6/-AGT CCG TGG TAG GGC AGG TTG GGG TGA CT-3’) modification to enrich human α-thrombin from serum. The structure and properties of the materials were confirmed by scanning electron microscope (SEM), Fourier transform infrared spectroscope (FT-IR), and X-ray photoelectron spectra (XPS). The adsorption ability and selectivity were studied and the thrombin was detected with liquid chromatography-mass spectrometry (LC–MS). The adsorption of thrombin onto the sorbent was achieved within 30 min and the desorption was realized using 5.0 mL of acetonitrile/water (80/20, v/v). The thrombin was quantified by LC–MS according to its characteristic peptide sequence of ELLESYIDGR.

In this work, a metal–organic framework MIL-68(In)–NH2 incorporated high internal phase emulsion polymeric monolith (MIL-68(In)–NH2/polyHIPE) was prepared and applied as a solid phase extraction adsorbent for the extraction and detection of trace triazine herbicides in environmental water samples by coupling with HPLC-UV detection. The fabricated material showed good adsorption for simazine, prometryn, and prometon in water samples because of π–π interactions and hydrogen bonding interactions. Under optimal conditions, the maximum adsorption capacity of simazine, prometon and prometryn was 800 μg g−1, 800 μg g−1 and 6.01 mg g−1, respectively. The linearities were 10–800 ng mL−1 for simazine, prometon and prometryn. The limits of detection were 31–97 ng L−1, and the recoveries were 85.6–118.2% at four spiked levels with relative standard deviations lower than 5.0%. The method has a high sensitivity for the determination of three triazine herbicides in environmental water samples.

In this study, monodisperse magnetic carbon microspheres were successfully synthesized through the carbonization of phenolic resin encapsulated Fe

In this work, graphene oxide-hybridized high internal emulsion polymers with crosslinking and open-cell structure was prepared and applied for separation and enrichment of estrogens. The prepared graphene oxide-hybridized high internal emulsion polymer monoliths had hydrophobicity, porosity and stability, which were just obtained by one step in-situ emulsion polymerization of 2-ethylhexyl acrylate, glycidyl methacrylate, and divinylbenzene after doping with graphene oxide. Benefit from the advantages of its unique character, the graphene oxide-hybridized high internal emulsion polymers monolith with low background pressure (85 kPa) and high mechanical strength could be applied for efficient separation for trace estrogens in urine. Under the optimized condition, trace estrogens, including estrone, estradiol, and diethylstilbestrol in urine, were detected by high-performance liquid chromatography, all the sample preparation process were carried out in 15 min, the recovery rate was ranged from 85.0 to 106.0% and the relative standard deviation was less than 4.

Polymerized high internal phase emulsion (polyHIPE) monoliths were prepared and applied as adsorbent materials for solid-phase extraction (SPE) of malachite green (MG) and leucomalachite green (LMG) from water samples. The polyHIPE monoliths were prepared by post-functionalization of monolithic surface with 6-aminocaproic acid (ACA) via ring opening reaction of epoxy groups in glycidyl methacrylate (GMA)-based polyHIPEs, and then applied to the preconcentration and determination of trace MG and LMG in environmental water samples by combing with high-performance liquid chromatography (HPLC). Taking MG and LMG as targets, main factors affecting SPE performance of the polyHIPE monoliths were investigated. Under the optimized conditions, the ACA-functionalized polyHIPE monoliths could effectively preconcentrate MG and LMG from 150 mL of water samples, and the recoveries of MG and LMG at three spiked levels were ranged from 84.8 to 97.4% with the relative standard deviations (RSDs) lower than 6%. The proposed method exhibited good linearity in the range of 2–200 ng mL–1, with low limits of detection of 17.0 and 8.7 pg mL–1 for MG and LMG, respectively. In addition, the prepared ACA-modified polyHIPE monolith showed good durability and stability, and it could be reused for 200 cycles without obvious losing the extraction performance.

Owing to the remarkable physicochemical properties such as hydrophobicity, conductivity, elasticity, and light weight, graphene-based materials have emerged as one of the most appealing carbon allotropes in materials science and chemical engineering. Unfortunately, pristine graphene materials lack functional groups for further modification, severely hindering their practical applications. To render graphene materials with special characters for different applications, graphene oxide or reduced graphene oxide has been functionalized with different organic agents and assembled together, via covalent binding and various noncovalent forces such as π-π interaction, electrostatic interaction, and hydrogen bonding. In this review, we briefly discuss the state-of-the-art synthetic strategies and properties of organic-functionalized graphene-based materials, and then, present the prospective applications of organic-functionalized graphene-based materials in sample preparation.

In this study, reduced graphene oxide (rGO) hybridized high internal phase emulsions were developed and polymerized as porous carriers for aptamer (5'/5AmMC6/-AGT CCG TGG TAG GGC AGG TTG GGG TGA CT-3') modification to enrich human α-thrombin from serum. The structure and properties of the materials were confirmed by scanning electron microscope (SEM), Fourier transform infrared spectroscope (FT-IR), and X-ray photoelectron spectra (XPS). The adsorption ability and selectivity were studied and the thrombin was detected with liquid chromatography-mass spectrometry (LC-MS). The adsorption of thrombin onto the sorbent was achieved within 30 min and the desorption was realized using 5.0 mL of acetonitrile/water (80/20, v/v). The thrombin was quantified by LC-MS according to its characteristic peptide sequence of ELLESYIDGR.

A simple and rapid fluorescence “on-off-on” approach for sensing Hg2+ and paraquat was designed by using nitrogen doped graphene quantum dots (N-GQDs) and N-GQDs/Hg2+ system, respectively. It was found that the fluorescence of N-GQDs solution was quenched in the presence of Hg2+ ions (turn off), and the quenched N-GQDs/Hg2+ system was recovered after addition of paraquat (turn on), due to the higher affinity of paraquat and Hg2+ than that of N-GQDs and Hg2+ that resulting into the release of Hg2+ from the surface of N-GQDs and the fluorescence recovery of N-GQDs. The developed fluorescence “on-off-on” approach exhibited high selectivity and sensitivity for detection of Hg2+ and paraquat. Under the optimum experimental conditions, good linearities were achieved over the range of 0–4.31 μM for Hg2+ and 0.05–2.0 μg mL−1 for paraquat, respectively. The detection limits for Hg2+ and paraquat were 23 nM and 19 μg L−1, respectively, and the recoveries of Hg2+ and paraquat spiked in real samples ranged from 95% to 105.8%. Results of this study suggested that the highly selective and sensitive fluorescence “on-off-on” approach can be used to the detection of Hg2+ and paraquat in real environmental water samples.

In this study, electrospun graphene oxide–doped poly(acrylonitrile-co-maleic acid) nanofibers (E-spun-GO-PANCMA-NFs) were fabricated and investigated as novel adsorbent for solid phase extraction (SPE) of tetracycline antibiotics (TCs) in chicken samples. The as-synthesized E-spun-GO/PANCMA-NFs were characterized and then used as SPE adsorbent to combine with high-performance liquid chromatography-fluorescence detection (HPLC-FLD) for simultaneous determination of four TCs (tetracycline, oxytetracycline, chlorotetracycline, and doxycycline). The experimental parameters affecting the analytical performance of this method, including sample pH, ionic strength, solvent type, volume and time desorption, and sample volume, were optimized. Under the optimized conditions, the proposed method provided good linearity from 5 to 500 ng/mL, with correlation coefficients higher than 0.9990, limits of detection from 20.4 to 44.8 μg/kg, and limits of quantification from 69.7 to 115.5 μg/kg. The intra- and inter-day RSDs were less than 5%. The recoveries of TCs spiked in chicken muscle samples were from 84.7 to 106.3% with RSDs in the range of 0.4–4.5%. Finally, the proposed E-spun-GO/PANCMA-NF-based SPE-HPLC-FLD method has been successfully applied to the analysis of TCs in chicken tissue samples, and thus offered a great prospect for TC analysis mainly in the applications of food quality and safety protection.

In this work, a novel Fe3O4@Cu3(btc)2-embedded polymerized high internal phase emulsion (Fe3O4@HKUST-1-polyHIPE) monolithic cake was synthesized, characterized and used as an adsorbent in the magnetic stir cake sorptive extraction (MSCSE) and determination of tetracycline antibiotics (TCs) in food samples by a combination of with high-performance liquid chromatography–fluorescence detection (HPLC-FLD). The prepared Fe3O4@HKUST-1-polyHIPE monolithic composites displayed a strong extraction ability and high column capacity due to enhanced interactions such as π–π interactions, hydrogen bonding, and electrostatic interactions. The extraction and desorption conditions were evaluated, and the calibration curves of four spiked TCs were linear (R2 ≥ 0.9991) in the range from 20 to 800 ng mL−1 for milk and egg samples, and 20 to 800 ng g−1 for chicken muscle and kidney samples. The limits of detection and the limits of quantification of the four TCs by using the proposed MSCSE-HPLC-FLD method were in the range of 1.9–4.6 and 5.5–13.9 ng mL−1 for milk and egg samples, and 1.8–3.7 and 5.3–13.0 ng g−1 for chicken muscle and kidney samples, respectively. The recoveries of the target TCs from spiked food samples were in the range from 86.6 to 110.7% with relative standard deviations lower than 7.0%. The proposed method was successfully applied for the determination of these four TCs in milk, egg, chicken muscle, and kidney samples.

Herein, a novel fluorescent probe was developed for the selective and sensitive detection of triclosan (TCS), which is based on turn-on fluorescence of quenched nitrogen silicon doped graphene quantum dot and ruthenium(III) ion (Si-GQDs/Ru3+) systems. Ru3+ is combined with Si-GQDs which thereby quenches the fluorescence, while the Si-GQDs/Ru3+ complex can be dissociated after the addition of TCS, resulting in fluorescence turn-on. The recovered fluorescence intensity was proportional to the concentration of TCS. The linear range of the probe for TCS detection was 500–25 000 ng L−1, with a low detection limit of 173 ng L−1. This detection platform has been successfully applied for the detection of TCS in both toothpaste and water samples.

Red-emissive nitrogen doped carbon quantum dots (N-CQDs) were synthesized by a facile and efficient microwave-assisted hydrothermal treatment of p-phenylenediamine (p-PD), and then applied for the highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples. The synthesized N-CQDs exhibited strong red emission with a 27.6% quantum yield (QY) and high stability. Under the optimized experimental conditions, the as-prepared red-emissive N-CQDs were employed as a fluorescent probe to successfully detect trace alachlor, and their fluorescence presented a good linear decline with the increase of the alachlor concentration from 0.005 to 150 μM with a limit of detection of 0.2 nM. The N-CQDs as a fluorescent probe were used for the detection of alachlor in soil samples with satisfactory recoveries ranging from 86.6–114.3%, indicating that they were a promising fluorescent probe for highly selective and sensitive determination of alachlor.

In this work, a porous capillary monolithic column was simply prepared by in situ thiol-alkyne click polymerization of dipentaerythritol hexakis (3-mercaptopropionate) and dimethyl dipropargylmalonate in fused-silica capillary. The capillary monolithic column shows excellent permeability, high porosity, and thoiether-rich groups, thereby, a high-efficient capacity for trace estrogens from complex samples are obtained via electron-donor-acceptor π-π interaction and hydrophobic interaction. The highest adsorption efficiency for estrogens is achieved at pH = 7.0 with a flow rate of 0.200 mL min

In this work, a metal-organic framework MIL-68(In)-NH

Surface wettability greatly influences the adsorptive, catalytic, and diffuse performances of a porous material. To realize the improved adsorption performance to hydrophilic heterocyclic amines (HAs), polymeric high internal phase emulsions (polyHIPEs) that can be tuned from hydrophobic to hydrophilic is synthesized by facilely regulating the amount of metal organic frameworks (MOFs). The water contact angle of the MOFs and polyHIPEs hybrids (MOFs@polyHIPEs) decreases from 133° to 0° as the amount of amide-modified MOFs increases from 0% to 10%. The hydrophilization of divinybenzene (DVB) based polyHIPEs by MOFs hybridization significantly enhances their adsorption performance and enables them to be suitable for the solid phase extraction (SPE) of hydrophilic HAs. Under the optimized conditions, the MOFs@polyHIPEs achieve adsorption capacities ranging from 42.89 to 86.71 µg/g for HAs through the π-π interaction and hydrogen bonding. The adsorption follows the pseudo-second-order kinetic model, and the nitrogen atoms in/on the imidazole ring are identified as the active adsorption sites for hydrogen bonding. This SPE method, along with HPLC-MS detection, provides detection limits of HAs as low as 0.00020-0.00040 ng/mL. This work offers a feasible strategy in tuning the surface wettability of polyHIPEs without post-modification to achieve high-efficiency enrichment and analysis of HAs.

Polymerized high internal phase emulsions as highly porous adsorption materials have received increasing attention and wide applications in separation science in recent years due to their remarkable merits such as highly interconnected porosity, high permeability, good thermal and chemical stability, and tailorable chemistry. In this review, we attempt to introduce some strategies to utilize polymerized high internal phase emulsions for separation science, and highlight the recent advances made in the applications of polymerized high internal phase emulsions for diverse separation of small organic molecules, carbon dioxide, metal ions, proteins, and other interesting targets. Potential challenges and future perspectives for polymerized high internal phase emulsion research in the field of separation science are also speculated at the end of this review.

The structural information and spatial distribution of molecules in biological tissues are closely related to the potential molecular mechanisms of disease origin, transfer, and classification. Ambient ionization mass spectrometry imaging is an effective tool that provides molecular images while describing in situ information of biomolecules in complex samples, in which ionization occurs at atmospheric pressure with the samples being analyzed in the native state. Ambient ionization mass spectrometry imaging can directly analyze tissue samples at a fairly high resolution to obtain molecules in situ information on the tissue surface to identify pathological features associated with a disease, resulting in the wide applications in pharmacy, food science, botanical research, and especially clinical research. Herein, novel ambient ionization techniques, such as techniques based on spray and solid-liquid extraction, techniques based on plasma desorption, techniques based on laser desorption ablation, and techniques based on acoustic desorption were introduced, and the data processing of ambient ionization mass spectrometry imaging was briefly reviewed. Besides, we also highlight recent applications of this imaging technology in clinical researches and discuss the challenges in this imaging technology and the perspectives on the future of the clinical research.

A porous carbon absorbent was obtained by using high internal phase emulsions (HIPEs) polymerization followed by high temperature carbonization under nitrogen protection. Graphene oxide (GO) and silica nanoparticles were doped into the HIPEs to enhance the adsorption ability and reusability. Fourier infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy were used for characterization and several parameters of separation and enrichment of trifluralin. The results showed that a hyper-crosslink framework material was obtained with abundant porous (pore size of about 30 μm) and a good adsorption and separation efficiency. The adsorption rate was up to 100% and trifluralin was completely eluted from the absorbent by 2.0 mL of an acetic acid-acetonitrile mixture. Graphical abstractSchematic representation of synthesis of porous carbon absorbent by GO and SiO

In this work, a convenient and sensitive solid phase extraction (SPE) method was developed based on graphene oxide functionalized cotton fiber (GO-CF), a SPE sorbent followed by liquid chromatography-fluorescence detection (LC-FLD) for determination of trace indole acetic acid, indole propionic acid, indole butyric acid and naphthalene acetic acid. GO-CF was synthesized via covalent bonding method on the surface of cotton fiber, and exhibited higher extraction capacity in comparison with that of cotton fiber. The conditions affecting the extraction efficiency, including sample pH, elution solvent, elution volume, extraction time, and sample volume, were optimized to obtain high extraction recoveries. Under optimal conditions, the calibration curves were linear over the concentration ranging from 2 to 200 ng mL−1 with correlation coefficients between 0.9987 and 0.9998 for all the analytes. The limits of detection were lower than 0.371 ng mL−1 for the four auxins. The intra- and inter-day relative standard deviations (RSDs) were less than 3.5 and 7.1%, respectively. The mean recoveries ranged from 73.5 to 105.4% with RSDs lower than 12.6%. The developed GO-CF–SPE–LC-FLD method has been successfully applied to the analysis of four auxins in real plant samples, including mung bean stalk, mung bean sprout, and tobacco leaf samples.

Reduced graphene oxide (RGO)-hybridized polymeric high-internal phase emulsions (RGO/polyHIPEs) with an open-cell structure and hydrophobicity have been successfully prepared using 2-ethylhexyl acrylate and ethylene glycol dimethacrylate as the monomer and the cross-linker, respectively. The adsorption mechanism and performance of this RGO/polyHIPEs to polycyclic aromatic hydrocarbons (PAHs) were investigated. Adsorption isotherms of PAHs on RGO/polyHIPEs show that the saturated adsorption capacity is 47.5 mg/g and the equilibrium time is 8 h. Cycling tests show that the adsorption capacity of RGO/polyHIPEs remains stable in 10 adsorption-desorption cycles without observable structure change in RGO/polyHIPEs. Moreover, the PAH residues in water samples after being purified by RGO/polyHIPEs are lower than the limit values in drinking water set by the European Food Safety Authority. These results demonstrate that the RGO/polyHIPEs have great potentiality in PAH removal and water purification.

Hypercrosslinked porous polymer hybridized graphene oxide with polymeric high internal phase emulsions (polyHIPEs/GO) were designed as versatile composites for water treatment. Morphologies, chemical composition and thermal stability of the composites were characterized by SEM, FTIR, XPS, XRD and TGA. Tunable adsorption properties and enhanced visible-light photocatalysis towards organic dyes were achieved by the manipulation of functional groups and the inclusion of Ag3PO4, respectively. The adsorption capacity of polyHIPEs/GO towards cationic methyl blue (MB) and rhodamine B (RB) is 1250.3 and 1054.1 μg g−1, respectively. Aminated polyHIPEs/GO (polyHIPEs(NH2)/GO) possesses an adsorption capacity of 1967.3 μg g−1 to anionic eosin Y (EY). The tandem columns of polyHIPEs(NH2)/GO and polyHIPEs/GO can successively and selectively remove the cationic and anionic dyes in a mixed dye solution. Furthermore, enhanced photodegradation ability was obtained after GO reduction and Ag3PO4 addition on polyHIPEs(NH2)/GO. Results show that 3.5 × 10−5 M of MB, RB and EY can be completely photodegraded by 20 mg of the novel photocatalyst within 20, 40 and 35 min, respectively. This work demonstrates that polyHIPEs/GO exhibits tunable properties for multiply progressive applications in water treatment and catalysis.

In this study, amphiphilic and porous copolymers were successfully prepared by doping a carboxylated carbon nanotube aqueous phase into a styrene and divinylbenzene oil phase, followed by a simple thermal polymerization to form high internalphase emulsions (polyHIPEs-CNTs). Hypercrosslinking and interconnecting chambers were formed with abundant open-cell pores with sizes ranging from 400 nm to 3.0 µm. Infrared spectroscopy, scanning electron microscopy, water contact angle measurements, and adsorption–desorption measurements were used to evaluate the characteristics of the material. The synthesized copolymers were demonstrated to be suitable for the separation of triazine herbicides from soil under optimized operating conditions. The maximum adsorption capacities of simazine, prometon, and prometryn were 25.4, 26.5, and 27.8 µg/g, respectively; the mean recoveries ranged from 87.56 to 97.67%, with a relative standard deviation lower than 4.5%. The polymers were stable, and the adsorption and desorption of the triazine herbicides were completed within a short period (10 min) without obvious interference. Adsorption isotherms revealed that the adsorption was co-determined by multiple effects between the adsorbents and compounds. An excellent reuse performance was observed, and the proposed polymers were believed to be potential materials for sample pretreatment in environmental science and pollutant cleaning engineering.

A novel continuous microwave-assisted enzymatic digestion (cMAED) method is proposed for the digestion of protein from Scomberomorus niphonius to obtain potential antioxidant peptides. In this study, bromelain was found to have a high capacity for the digestion of the Scomberomorus niphonius protein. The following cMAED conditions were investigated: protease species, microwave power, temperature, bromelain content, acidity of the substrate solution, and incubation time. At 400W, 40°C, 1500U·g-1 bromelain, 20% substrate concentration, pH 6.0 and 5min incubation, the degree of hydrolysis and total antioxidant activity of the hydrolysates were 15.86% and 131.49μg·mL-1, respectively. The peptide analyses showed that eight of the potential antioxidant peptide sequences, which ranged from 502.32 to 1080.55Da with 4-10 amino acid residues, had features typical of well-known antioxidant proteins. Thus, the new cMAED method can be useful to obtain potential antioxidant peptides from protein sources, such as Scomberomorus niphonius.

Electrospun reduced graphene oxide/TiO

In this study, novel porous carbon composites were successfully prepared with graphene-modified high-internal-phase emulsions (HIPEs) via a simple process of polymerization followed by carbonization. The morphology of the macroporous composites was observed and the verification of structural and functional groups were verified by scanning electron microscopy (SEM), and other characterizations techniques including Fourier transform infrared (FI-IR), X-ray photoelectron spectroscopy (XPS) spectra and Raman spectroscopy. The prepared porous carbon composites were applied to farmland water for the simultaneous adsorption of triazine herbicides and the conditions of extraction and desorption were optimized. Due to the π-π interaction and hydrophobic interaction between triazine herbicides and carbon composites, the maximum adsorption capacity of simazine, prometon and prometryn were 33.4, 34.5 and 33.8 μg g−1, respectively. Adsorption and desorption of triazine herbicides can be achieved in 10 min, and high-speed mass transfer was observed. The calibration curves of three triazine herbicides were linear (R2 ≥0.9996) in the range from 25.0 to 500.0 ng mL−1. The LOD of three triazine herbicides by using the proposed SPE-HPLC-DAD method were 2.5–5.6 ng mL−1. All the results suggest that these materials may be useful for more efficient hazardous residue separations.

Bismuth oxybromide/molybdenum disulfide/graphene oxide (BiOBr/MoS2/GO) heterojunction composites were fabricated to modulate the adsorption ability and photocatalytic degradation performance toward oxytetracycline (OTC). The flowerlike BiOBr/MoS2/GO composites demonstrated excellent photocatalytic activies for the OTC degradation. Specifically, OTC, tetracycline, chlorotetracycline, and doxycycline were simultaneously removed with degradation rates higher than 98% under visible light irradiation within 40 min. Radical trapping experiments indicated that photogenerated holes (h+), hydroxyl radicals ( OH), and superoxide radicals ( O2−) played crucial roles in photocatalytic OTC degradation. Further, Possible transformation pathway and photocatalytic mechanism were proposed by investigating the intermediates in OTC degradation process.

Polymerized high internal phase emulsion (polyHIPE) monoliths were synthesized by in situ polymerization of the continuous phase of a high internal phase emulsion (HIPE) in syringes and successfully applied as monolithic sorbents to extract Para Red and Sudan dyes in chilli samples. Several parameters affecting the extraction efficiency were investigated, including the type of desorption solvent, sample loading rate, sample volume, and pH. Under the optimized conditions, a method using a monolithic polyHIPE column combined with high-performance liquid chromatography (HPLC) was developed for the simultaneous extraction and sensitive determination of Para Red and Sudan dyes in chilli samples. The proposed method had good linearity, with correlation coefficients (R 2) from 0.9985 to 0.9995 and low detection limits (LODs, S/N = 3) in the range 1.5–12 ng/mL for the five analytes. The mean recoveries were ranged from 82.6 to 114.3% with relative standard deviations (RSDs) lower than 4.2%.

In this work, a magnetic metal-organic framework designated as MIL-100(Fe) was prepared and applied as a magnetic solid-phase extraction sorbent for the determination of trace polycyclic aromatic hydrocarbons in environmental water samples by coupling with high-performance liquid chromatography and fluorescence detection. The magnetic microspheres exhibited large surface areas and high extraction ability, making them excellent candidates as sorbents for enrichment of trace polycyclic aromatic hydrocarbons. Under the optimized experimental conditions, good sensitivity levels were achieved with low detection limits ranging from 32 to 2110 pg/mL and good linearities with correlation coefficients higher than 0.9990 for the investigated 13 polycyclic aromatic hydrocarbons. The proposed method has been validated in the analysis of real water samples with mean recoveries in the range of 81.4-126.9% at four spiked levels and the relative standard deviations in the range of 1.3-17.0%. The magnetic MIL-100(Fe) microspheres were stable enough for 150 extractions without a significant loss of extraction performance.

Sulfur-doped carbon quantum dots (S-CQDs) with stable blue fluorescence were synthesized through a facile one-step hydrothermal method by using ascorbic acid and thioglycolic acid as carbon and sulfur sources. The prepared S-CQDs exhibited a sensitive and selective response to Fe3+ ions in comparison with Fe2+ and other metal ions, In the presence of adequate H2O2, Fe2+ was completely transformed to Fe3+ that is the determinable form of iron ions, and the difference in the change of the fluorescence intensity of S-CQDs before and after adding H2O2 was used for detection of Fe2+ and Fe3+ ions, respectively. Under the optimum experimental conditions, the fluorescence intensity of S-CQDs gradually decreased with increasing of Fe3+ concentration ranging from 0 to 200 μM. Good linearity was achieved over the range of 0-200 μM. The detection limit of the developed method was 0.050 μM for Fe3+. The recoveries of Fe2+ and Fe3+ spiked in real samples ranged from 98.2% to 112.4%. Finally, the proposed S-CQDs integrated with Fenton system was applied to the detection of Fe2+ and Fe3+ ions in oral ferrous gluconate samples, which presents potential applications in the speciation and determination of Fe2+ and Fe3+ ions in complex samples.

Electrospun reduced graphene oxide/TiO2/poly(acrylonitrile-co-maleic acid) composite nanofibers (E-spun RGO/TiO2/PANCMA NFs) were fabricated using electrospinning of the dispersive solution of PANCMA, GO and TiO2 followed by post-chemical reduction. The obtained composite nanofibers were compressed in a dialyzer and then used to absorb and degrade malachite green (MG) and leucomalachite green (LMG) from aqueous solution. Compared to the E-spun TiO2/PANCMA and GO/TiO2/PANCMA NFs, the E-spun RGO/TiO2/PANCMA NFs exhibited higher adsorption capacity and photocatalytic degradation ability. Under optimized conditions, 90.6% of MG and 93.7% of LMG from 50 mL aqueous sample solution were adsorbed on the RGO/TiO2/PANMA NFs (3.0 mg fibers) in 2.0 min, and subsequent the 91.4% and 95.2% of MG and LMG adsorbed on the NFs were degradated in 60 min under UV irradiation, respectively. In addition, the E-spun RGO/TiO2/PANMA NFs exhibited good reusability and could be reused in multiple cycles of operations for adsorption and photocatalytic degradation of MG and LMG. This work demonstrated that the electrospun composite nanofibers are promising materials for removal of pollutants from environmental water samples.

Sulfur-doped carbon quantum dots (S-CQDs) with stable blue fluorescence were synthesized through a facile one-step hydrothermal method by using ascorbic acid and thioglycolic acid as carbon and sulfur sources. The prepared S-CQDs exhibited a sensitive and selective response to Fe

A new class of solid-phase extraction column prepared with grafted mercapto-silica polymerized high internal phase emulsion particles was used for the preconcentration of trace lead. First, mercapto-silica polymerized high internal phase emulsion particles were synthesized by using high internal phase emulsion polymerization and carefully assembled in a polyethylene syringe column. The influences of various parameters including adsorption pH value, adsorption and desorption solvents, flow rate of the adsorption and desorption procedure were optimized, respectively, and the suitable uploading sample volumes, adsorption capacity, and reusability of solid phase extraction column were also investigated. Under the optimum conditions, Pb(2+) could be preconcentrated quantitatively over a wide pH range (2.0-5.0). In the presence of foreign ions, such as Na(+) , K(+) , Ca(2+) , Zn(2+) , Mg(2+) , Cu(2+) , Fe(2+) , Cd(2+) , Cl(-) and NO3 (-) , Pb(2+) could be recovered successfully. The prepared solid-phase extraction column performed with high stability and desirable durability, which allowed more than 100 replicate extractions without measurable changes of performance. The feasibility of the developed method was further validated by the extraction of Pb(2+) in rice samples. At three spiked levels of 40.0, 200 and 800 μg/kg, the average recoveries for Pb(2+) in rice samples ranged from 87.3 to 105.2%.

A polymerized high internal phase emulsion monolith was used as a novel sorbent for solid-phase extraction coupled with high-performance liquid chromatography and fluorescence detection for the determination of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline in environmental water samples. The polymerized high internal phase emulsion monolithic column was prepared by the in situ polymerization of the continuous phase of a high internal phase emulsion containing glycidyl methacrylate, styrene, and divinylbenzene in pipette tips, and then functionalized with iminodiacetic acid. The resulting monolith exhibited highly interconnected porosity and large surface areas, making it an excellent candidate as an solid-phase extraction sorbent for the enrichment of trace tetracycline antibiotics. Several factors affecting the extraction performance of polymerized high internal phase emulsion monoliths, including the pH of sample solution, the eluting solvents, the sample loading flow rate and volume, were investigated, respectively. Under the optimized conditions, the mean recoveries of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline spiked in pond and farm wastewater samples ranged from 78.1 to 119.3% with relative standard deviation less than 15%. The detection limits (S/N = 3) of the proposed method were in the range of 51-137 pg/mL. This study demonstrated that the monolithic polymerized high internal phase emulsion would be promising solid-phase extraction sorbents in the extraction and proconcentration of trace analytes from complex samples.

The aroma compounds in the Chinese vinegar has been profiling by the technology of Headspace solid phase microextraction (HS-SPME) hybrid with gas chromatography mass spectrometry (GC-MS). Thirteen compounds were selected as the key aroma compounds to discriminate two protected geographical origin (PGI) Chinese vinegars named Shanxi extra-aged vinegar and Zhenjiang vinegar by using principal component analysis. The results demonstrate that volatile organic components as the markers combined with the appropriate chemometrics method can be used for PGI Chinese vinegar discrimination with good reliability.

High-internal-phase-emulsion polymers (polyHIPEs) show great promise as solid-phase-extraction (SPE) materials because of the tremendous porosity and highly interconnected framework afforded by the high-internal-phase-emulsion (HIPE) technique. In this work, polyHIPE monolithic columns as novel SPE materials were prepared and applied to trace enrichment of cytokinins (CKs) from complex plant samples. The polyHIPE monoliths were synthesized via the in-situ polymerization of the continuous phase of a HIPE containing styrene (STY) and divinylbenzene (DVB) in a stainless column, and revealed highly efficient and selective enrichment ability for aromatic compounds. Under the optimized experimental conditions, a method using a monolithic polyHIPE column combined with liquid chromatography–electrospray tandem mass spectrometry (LC–MS–MS) was developed for the simultaneous extraction and sensitive determination of trans-zeatin (tZ), meta-topolin (mT), kinetin (K), and kinetin riboside (KR). The proposed method had good linearity, with correlation coefficients (R 2) from 0.9957 to 0.9984, and low detection limits (LODs, S/N = 3) in the range 2.4–47 pg mL−1 for the four CKs. The method was successfully applied to the determination of CKs in real plant samples, and obtained good recoveries ranging from 68.8 % to 103.0 % and relative standard deviations (RSDs) lower than 16 %.

Aptamer-functionalized materials (AFMs) are promising specific recognition materials in sample-preparation techniques due to the inherently high affinity and selectivity associated with aptamers, so AFMs attract considerable interest and a wide variety of applications to recognize specific target analytes ranging from small molecules to proteins, cells and even tissues. We briefly introduce sample-preparation techniques and potential applications of aptamers in analytical chemistry, and then briefly discuss the preparation of AFMs. We mainly focus on developments and applications of AFMs in sample-preparation techniques, including AF solid-phase extraction, solid-phase microextraction, and microfluidic sample preparation, and other sample-preparation techniques. We also discuss the challenges and the prospects of AFMs in sample preparation in future developments.

A novel large-volume immobilized enzyme reactor (IMER) on small column was prepared with organic-inorganic hybrid silica particles and applied for fast (10 min) and oriented digestion of protein. At first, a thin enzyme support layer was formed in the bottom of the small column by polymerization with α-methacrylic acid and dimethacrylate. After that, amino SiO2 particles was prepared by the sol-gel method with tetraethoxysilane and 3-aminopropyltriethoxysilane. Subsequently, the amino SiO2 particles were activated by glutaraldehyde for covalent immobilization of trypsin. Digestive capability of large-volume IMER for proteins was investigated by using bovine serum albumin (BSA), cytochrome c (Cyt-c) as model proteins. Results showed that although the sequence coverage of the BSA (20%) and Cyt-c (19%) was low, the large-volume IMER could produce peptides with stable specific sequence at 101-105, 156-160, 205-209, 212-218, 229-232, 257-263 and 473-451 of the amino sequence of BSA when digesting 1mg/mL BSA. Eight of common peptides were observed during each of the ten runs of large-volume IMER. Besides, the IMER could be easily regenerated by reactivating with GA and cross-linking with trypsin after breaking the -C=N- bond by 0.01 M HCl. The sequence coverage of BSA from regenerated IMER increased to 25% comparing the non-regenerated IMER (17%). 14 common peptides. accounting for 87.5% of first use of IMER, were produced both with IMER and regenerated IMER. When the IMER was applied for ginkgo albumin digestion, the sequence coverage of two main proteins of ginkgo, ginnacin and legumin, was 56% and 55%, respectively. (Reviewer 2) Above all, the fast and selective digestion property of the large-volume IMER indicated that the regenerative IMER could be tentatively used for the production of potential bioactive peptides and the study of oriented protein digestion.

In this study, an easy and efficiency protein digestion method called continuous microwave-assisted protein digestion (cMAED) with immobilized enzyme was developed and applied for proteome analysis by LC-MS(n). Continuous microwave power outputting was specially designed and applied. Trypsin and bromelain were immobilized onto magnetic micropheres. To evaluate the method of cMAED, bovine serum albumin (BSA) and protein extracted from ginkgo nuts were used as model and real protein sample to verify the digestion efficiency of cMAED. Several conditions including continuous microwave power, the ratio of immobilized trypsin/BSA were optimized according to the analysis of peptide fragments by Tricine SDS-PAGE and LC-MS(n). Subsequently, the ginkgo protein was digested with the protocols of cMAED, MAED and conventional heating enzymatic digestion (HED) respectively and the LC-MS(n) profiles of the hydrolysate was compared. Results showed that cMAED combined with immobilized enzyme was a fast and efficient digestion method for protein digestion and microwave power tentatively affected the peptide producing. The cMAED method will be expanded for large-scale preparation of bioactive peptides and peptide analysis in biological and clinical research.

Multicomposition fingerprints with several chemical compositions containing inorganic elements and organic compounds (amino acids, polyhydric alcohols, organic acids) were measured to distinguish two geographical indication-protected vinegars (GIs) from general vinegars (nGIs). The two of GIs were named Shanxi extra aged vinegar and Zhenjiang vinegar from Shanxi and Jiangsu province, respectively. Principal component analysis and Fisher linear discriminant methods were applied for the pattern recognition and classification of GI product. It was not suitable by simply using one kind of composition to make a distinction between GIs and nGIs. However, by using multicomposition to build a classify model, the classification of SXVs was described by Co, As, Al, Mg, Ca, erythritol, arabitol, sorbitol, proline, lysine and pyruvic acid, while ZJVs classification was described by threonine, serine, glycine, lysine, Ba, erythritol, xylitol and lactic acid. The GI samples can be classified with high accuracy according to the discriminant model, of which the false rate is 3.88 % in SXVs model and 10.85 % in ZJVs model. This method can be a useful method for protecting the geographical indication vinegars from the fake or adulterate vinegar commodities.

Microwave-assisted enzymatic digestion (MAED) technique was applied for ginkgo protein digestion with both free and immobilized enzyme. Under the optimized conditions of MAED (0.01 g/mL substrate concentration of bromelain, 4500 U/g enzyme/ginkgo protein, 30 min, 300 W microwave power), a higher digestion rate (7.50%) and a significant increase in antioxidant activity (72.7 mg/g) were obtained in contrast with the conventional methods. With the optimized digestion conditions (0.625% glutaraldehyde (v/v), 0.4 mg/mL initial concentration of bromelain and 4 h of immobilization), the activity and effectiveness factor of immobilized bromelain were respectively 86 U and 81.6%. The results of ginkgo digestion by applying MAED indicated that the digestion rate of immobilized bromelain obtained by MAED method (6.41%) was comparable to that of free bromelain in the conventional digestion (8.13%). In both case with immobilized and free bromelain while applying MAED, a homogeneously abundant distribution of peptide fragments (from 7.863 Da to 5856 Da) and a few different peptide profiles were found. This report brings in conclusion that applying MAED with immobilized enzyme has the potential to obtain the highest number of antioxidant activity peptides.