In situ fabrication of 3D COF-300 in a capillary for separation of aromatic compounds by open-tubular capillary electrochromatography.

Two-dimensional (2D) COFs have been successfully applied for various applications, such as capillary electrochromatography (CEC). Compared with 2D COFs, three-dimensional (3D) COFs have higher surface area and lower density, which should have superior potential as the separation medium in CEC. However, the 3D COFs on the inner wall of capillary is hard to fabricate in situ. Up to date, the application of 3D COFs in open-tubular capillary electrochromatography (OT-CEC) is still considered a challenge. For the first time the COF-300-coated capillary was prepared by in situ growth (COF-300 was made from terephthalaldehyde and tetra-(4-anilyl)-methane) on OT-CEC. Benzene, methylbenzene, styrene, ethylbenzene, naphthalene, 1-methylnaphthalene, and propylbenzene were used to evaluate the performance of the COF-300-coated capillary by OT-CEC. For three consecutive runs, the intraday relative standard deviations (RSDs) of migration time and peak areas were 0.1-0.4% and 2.5-8.3%, respectively. The interday RSDs of migration time and peak areas were 0.2-0.5% and 1.0-10.8%, respectively. Five groups of aromatic co mpounds were used to further study the separation mechanism, which indicated that hydrophobic interaction and size selection interaction are the main factors. It should be noted that the COF-300-coated capillary can be used for more than 140 runs with no observable changes of the separation efficiency. Graphical abstract The 3D COF-300-coated capillary was prepared by in situ growth for OT-CEC. Six groups of aromatic compounds were separated by 3D COF-300-coated capillary. Size selection and hydrophobic interaction affect the migration time of analytes.

Photochemical synthesis of magnetic covalent organic framework/carbon nanotube composite and its enrichment of heterocyclic aromatic amines in food samples.

The layered cladding sea cucumber-like covalent organic framework incorporated magnetic carbon nanotube (CTC-COF@MCNT) was prepared by photochemical synthesis. The magnetic composite was fabricated by filling magnetic nanoparticles inside carbon nanotubes and depositing covalent organic framework shell on the outside. The composites exhibited large specific surface area, high stability and adsorption capacity for heterocyclic aromatic amines. Therefore, CTC-COF@MCNT was applied as adsorbent for magnetic solid-phase extraction to enrich the heterocyclic aromatic amines from complex food samples prior to the determination by ultra-high performance liquid chromatography-tandem mass spectrometry. The adsorption mechanism between CTC-COF@MCNT and heterocyclic aromatic amines was discussed and verified by Gaussian simulation. The effect of adsorbent amount, extraction conditions and desorption conditions on the efficiency of pretreatment were optimized. The established method revealed wide linear range and high sensitivity with the LODs ranging from 0.0058 to 0.025 ng/g. Furthermore, the developed method was successfully applied to determine heterocyclic aromatic amines in fried chicken and roast beef. Satisfactory recoveries were obtained, which demonstrated the promising potential of CTC-COF@MCNT as good adsorbent for pretreatment of trace analytes.

Comparison of Stir Bar Sorptive Extraction and Solid Phase Microextraction of Volatile and Semi-Volatile Metabolite Profile of Staphylococcus Aureus.

For the analysis of volatile bacterial compounds, solid phase microextraction (SPME) is currently the most widely used metabolite concentration technique. Recently, the potential of stir bar sorptive extraction (SBSE) for this use has been demonstrated. These two approaches were therefore used in combination with gas-chromatography coupled with mass-spectrometry (GC-MS) for the analysis of volatile and semi-volatile bacterial compounds produced by Staphylococcus aureus. In both cases, SPME and SBSE/headspace sorptive extraction (HSSE) enrichment was carried out in two coating phases. A whole analytical and statistical process was developed to differentiate the metabolites produced from the metabolites consumed. The results obtained with SBSE/HSSE and SPME were compared and showed the recovery of 90% of the compounds by SBSE/HSSE. In addition, we were able to detect the production of 12 volatile/semi-volatile compounds by S. aureus, six of which had never been reported before. The extraction by SBSE/HSSE showed higher concentration capacities and greater sensitivity than SPME concerning bacterial compounds, suggesting that this technique may therefore become the new preferred option for bacterial volatile and semi-volatile compound analysis.

Developing boron nitride-pyromellitic dianhydride composite for removal of aromatic pollutants from wastewater via adsorption and photodegradation.

A series of boron nitride-pyromellitic dianhydride composites have been successfully synthesized by calcinating the mixtures of boron nitride (BN) and pyromellitic dianhydride (PA) at 350 °C, in which the composite (BNPA2) has the largest adsorption quantity (65.1 mg/g) for rhodamine B (RhB) and the best photo-removal efficiency for RhB under visible light irradiation. 1H NMR characterizations for BN, PA and BNPA2 suggest that this composite is formed via the reaction between the OH groups in BN and PA. BNPA2 can also adsorb neutral red (NR), methyl orange (MO), tetracycline (TC) and atrazine (AT). NR and MO can be photo-removed by BNPA2 under visible light irradiation. Colorless TC and AT can also be degraded by BNPA2 under visible light irradiation, suggesting that BNPA2 is visible light responsible photocatalyst. BNPA2 has the highest photo-removal efficiency for the cationic RhB and NR, followed by the anionic MO. This is from that BNPA2 has negative surface. When anionic MO mixes with cationic RhB (or NR) together, BNPA2 prefers to remove cationic RhB (or NR) from the mixture solution under visible light irradiation and the removal efficiency of anionic MO by BNPA2 is also increased. Thus, electrostatic interactions between dyes and BNPA2 as well as between dyes play significant role in the removal process. •O2- makes a main contribution for this photo-removal of these aromatic pollutants (dyes, TC and AT) by BNPA2 under visible light irradiation. Furthermore, the removal performance of BNPA2 for RhB, TC and AT can be effectively regenerated by visible light irradiation.

Akazamicin, a cytotoxic aromatic polyketide from marine-derived Nonomuraea sp.

In our screening program on marine-derived actinomycetes, Nonomuraea sp. AKA32 isolated from deep-sea water collected from a depth of 800 m in Sagami Bay, Japan was found to produce compounds cytotoxic to cancer cells. Activity-guided purification led to the isolation of a new aromatic polyketide, akazamicin (1), along with two known compounds, actinofuranone C (2) and N-formylanthranilic acid (3). Structures of these compounds were elucidated through the interpretation of NMR and MS spectroscopic data. Compounds 1, 2, and 3 displayed cytotoxicity against murine B16 melanoma cell line with the IC50 value of 1.7, 1.2, and 25 µM, respectively.

Aromatic compounds produced by endophytic fungi isolated from red alga Asparagopsis taxiformis - Falkenbergia stage.

Endophytic fungi were isolated from red alga Asparagopsis taxiformis - Falkenbergia stage, collected from the Brazilian coast, and were identified as Annulohypoxylon stygium (AT-03) and A. yungensis (AT-06) based on their macro/micromorphological and molecular features. Bioassay-guided fractionation of the EtOAc extract from laboratory cultures of both strains yielded known compounds pyrogallol from A. stygium, (3 R)-scytalone and (3 R,4 R)-4-hydroxy-scytalone from A. yungensis. Pyrogallol was active against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli strains. An inactive fraction from A. stygium afforded two additional compounds, (3 R,4 R)-3,4,5-trihydroxy-1-tetralone and tyrosol. Optically active compounds had their stereochemistry determined by circular dichroism (CD) spectroscopy.

Preparation of silica colloidal crystal column and its application in pressurized capillary electrochromatography.

Capillary column packed with silica colloidal crystals (SCC) exhibits great efficiency in liquid chromatography because of its highly-ordered structure and extremely narrow channels (about hundred nanometer in diameter) between the particles. However, problems arise due to the extremely high back-pressure created with its dense packings. It is also a challenge to prepare a stable SCC column with an appropriate length for chromatographic separation on a commercial instrument. We have synthesized monodispersed, sub-micron SiO2 particles bonded with C18 functionality and fabricated SCC capillary columns up to 100 mm in length. The packing materials in the column displayed Bragg diffraction with blueish color under irradiation with white light, indicating the formation of SCC. The column performance was evaluated using pressurized capillary electrochromatography (pCEC) and column efficiencies of more than a hundred thousand plates per column (plate height < 1 µm) were achieved using peptide as a sample. The run-to-run reproducibility expressed with RSD in terms of retention time and peak area for aromatic compounds were less than 0.076% and 1.96%, respectively. These results demonstrate that the combination of pCEC and SCC columns may provide an innovative analytical technique with extraordinary efficiency, resolution and speed for the separation of complex samples.

Characterization of UV-Sensitive Marker Constituents of Polygala Root for TLC: Applications in Quality Control of Single Crude Drug Extract Preparations.

Polygala Root (the root of Polygala tenuifolia WILLDENOW; Japanese name "Onji"), a well-known crude drug, traditionally used as an expectorant and sedative, has been attracting increased interest in recent years owing to its newly found pharmacological effect related to neuroprotection. However, there is no specific method for identifying and estimating the quality of this crude drug in the Japanese Pharmacopoeia, 17th edition. Therefore, in order to develop a TLC-based simple and convenient identification method using characteristic chemical marker(s) for the drug and its extract products, UV-sensitive constituents of Polygala Root were first investigated. A total of 23 aromatic compounds were isolated and characterized. Two new compounds, namely, polygalaonjisides A (1) and B (2), were characterized as syringic acid 4-O-(2'-O-ß-D-apiosyl)-ß-D-glucoside and 2-O-(ß-D-glucosyl)-3'-O-benzoylsucrose, respectively. Based on these phytochemical results, a TLC method focusing on three marker spots with Rf value of approximately 0.4-0.5 due to tenuifolisides A and B and 3,6'-di-O-sinapoylsucrose was proposed as a simple and convenient test to identify Polygala Root or its single-extract products on the market. The data presented in this paper could be useful in stipulating a confirmation test to identify Polygala Root.

Poly(3-hexylthiophene) stationary phase for gas chromatographic separations of aliphatic and aromatic isomers.

This work describes the investigation of utilizing a chain-typed thiophene-based π-conjugated polymer, i.e., poly(3-hexylthiophene) (P3HT), as the stationary phase for gas chromatography (GC). The P3HT column was statically prepared and investigated for its column efficiency, polarity, separation performance, repeatability and thermal stability. As a result, it showed moderate polarity and column efficiencies of 3260, 3310 and 3790 plates/m for 1-octanol, naphthalene and n-dodecane, respectively. As evidenced, it exhibited high-resolution performance for aliphatic and aromatic isomers, including those critical pairs such as phenanthrene/anthracene and p-/m-benzenediol isomers. Moreover, it displayed stronger retention for alkanes, alcohols and phenols in comparison to the polysiloxane stationary phase with close polarity. Also, the P3HT column had good repeatability and reproducibility with the RSD values less than 0.05% for run-to-run, 0.17-0.54% for day-to-day and 2.7-5.2% for column-to-column, and good thermal stability up to 260 °C. This work demonstrates the promising future of the thiophene-based polymer and its derivatives in separation science.

Removal of aromatic and hydrophobic fractions of natural organic matter (NOM) using surfactant modified magnetic nanoadsorbents (MNPs).

The present study investigated the potential of surfactant modified magnetic nanoadsorbents (MNPs) for the removal of aromatic and hydrophobic fractions of natural organic matter (NOM), leading to the formation of trihalomethanes (THMs) in chlorinated drinking water. Co-precipitation method was used for the synthesis of MNPs. However, MNPs have a tendency to form an agglomeration. Therefore, polyethylene glycol (PEG) was used as a surface modifier to reduce the agglomeration. The PEG-coated MNPs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), BET surface area, X-ray diffraction (XRD), Fourier transform spectrometer (FTIR), and zeta (ζ) potential. FESEM observation indicates that PEG-coated MNPs were spherical in shape and 25 nm in size. Zeta potential values (- 58.35 to - 74.9 mV) indicated excellent stability of PEG-MNPs. FTIR spectra indicated the presence of a -CH2 group, responsible for the chemical interaction between aromatic and humic content. Batch experiments were conducted by studying the effect of pH, contact time, and adsorbent dosage on NOM removal. Excellent removal of DOC (94.49%) and UV254 (89.32%) was observed at the optimum dose of adsorbent (0.75 g/L) and at pH 7.0. Adsorption kinetics followed pseudo-second-order reaction (R2, 0.973) and occurs by multilayer chemisorption which is due to the chemical interaction between aromatic and humic compounds of NOM with MNPs. Thus, MNPs showed great potential as a novel adsorbent for the removal of aromatic and hydrophobic compounds of NOM and can significantly be used to curtail the problem of THMs in drinking water supplies.

Urea functionalized surface-bonded sol-gel coating for on-line hyphenation of capillary microextraction with high-performance liquid chromatography.

Sol-gel urea functionalized-[bis(hydroxyethyl)amine] terminated polydimethylsiloxane coating was developed for capillary microextraction-high performance liquid chromatographic analysis from aqueous samples. A fused silica capillary is coated from the inside with surface bonded coating material and is created through in-situ sol-gel reaction. The urea-functionalized coating was immobilized to the inner surface of the capillary by the condensation reaction of silanol groups of capillary and sol-solution. The characterization of the coating material was successfully done by using X-ray photoelectron spectroscopy, thermogravimetric analysis, field emission scanning electron microscope, and energy dispersive X-ray spectrometer. To make a setup of online capillary microextraction-high performance liquid chromatography, the urea functionalized capillary was installed in the HPLC manual injection port. The analytes of interest were pre-concentrated in the coated sampling loop, desorbed by the mobile phase, chromatographically separated on C-18 column, and analyzed by UV detector. Sol-gel coated capillaries were used for online extraction and high-performance liquid chromatographic analysis of phenols, ketones, aldehydes, and polyaromatic hydrocarbons. This newly developed coating showed excellent extraction for a variety of analytes ranging from highly polar to non-polar in nature. The analysis using sol-gel coating showed excellent overall sensitivity in terms of lower detection limits (S/N = 3) for the analytes (0.10 ng mL-1-14.29 ng mL-1) with acceptable reproducibility that is less than 12.0%RSD (n = 3). Moreover, the capillary to capillary reproducibility of the analysis was also tested by changing the capillary of the same size. This provided excellent%RSD of less than 10.0% (n = 3).

Micro-solid phase extraction of benzene, toluene, ethylbenzene and xylenes from aqueous solutions using water-insoluble ß-cyclodextrin polymer as sorbent.

Water-insoluble ß-cyclodextrin polymer was synthesized by chemical cross-linking using epichlorohydrin (EPI) as a cross-linker agent. The produced water-insoluble polymer was used as a sorbent for the micro-solid phase extraction (µ-SPE) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples. The µ-SPE device consisted of a sealed tea bag envelope containing 15mg of sorbent. For the evaluation of the extraction efficiency, parameters such as extraction and desorption time, desorption solvent and salt concentration were investigated. At an extraction time of 30min in the course of the extraction process, analytes were extracted from a 10mL aqueous sample solution. The analytes were desorbed by ultrasonication in 200µL of acetonitrile for 20min. Analysis of the analytes was done by a gas chromatography-flame ionization detector (GC-FID) system. The enrichment factor (EF) was found to be in the range 23.0-45.4 (EFmax=50.0). The method provided linearity ranges of between 0.5 and 500.0ng/mL (depending on the analytes), with good coefficients of determination (r2) ranging between 0.997 and 0.999 under optimized conditions. Detection limits for BTEX were in the range of between 0.15 and 0.60ng/mL, while corresponding recoveries were in the range of 46.0-90.0%. The relative standard deviation of the method for the analytes at 100.0ng/mL concentration level ranged from 5.5 to 11.2% (n=5). The proposed method was concluded to be a cost effective and environmentally-friendly extraction technique with ease of operation and minimal usage of organic solvent.

Biodegradation of BTEX Aromatics by a Haloduric Microbial Consortium Enriched from a Sediment of Bohai Sea, China.

This study focused on a haloduric BTEX-degrading microbial consortium EC20 enriched from Bohai Sea sediment. EC20 degraded 87% of BTEX at 435 mg L-1 initial concentration (benzene, toluene, ethylbenzene, and xylenes in equal proportions) in the presence of 3.4% NaCl. 16S rRNA gene-based PCR-DGGE profiles revealed that the dominant bacteria in EC20 were Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes at the phylum level, and Pseudomonas, Mesorhizobium, Achromobacter, Stenotrophomonas, and Halomonas at the genus level. PCR detection of genes coding the key enzymes which participated in BTEX degradation pathways showed that the enriched consortium EC20 contained TOL pathway and TOD pathway to initiate biodegradation of BTEX.

Bioremediation of petroleum wastewater by hyper-phenol tolerant Bacillus cereus: Preliminary studies with laboratory-scale batch process.

Petroleum wastewater samples from oil refinery and oil exploration site were treated by hyper phenol-tolerant Bacillus cereus (AKG1 and AKG2) in laboratory-scale batch process to assess their bioremediation efficacy. Quality of the treated wastewater samples were analyzed in terms of removal of chemical oxygen demand (COD), total organic carbon (TOC) and ammonium nitrogen content, and improvement of biological oxygen demand (BOD). Adaptation of these bacteria to the toxic environment through structural changes in their cell membranes was also highlighted. Among different combinations, the co-culture of AKG1 and AKG2 showed the best performance in degrading the wastewater samples.

Facile one-pot preparation of a novel imidazolium-based monolith by thiol-ene click chemistry for capillary liquid chromatography.

In this work, a novel imidazolium-based monolith was fabricated through a simple route. With 1-vinyl-3-octadecylimidazolium bromide and ethylene dimethacrylate as monomers, pentaerythritol tetra-(3-mercaptopropionate) as crosslinker, AIBN as thermal initiator, the monolith was facilely fabricated by one-pot thiol-ene click chemistry. The influences of both the content of monomer/crosslinker and porogenic systems on the morphology, and permeability of the monolith were studied. The optimal reaction conditions were used to prepare a homogeneous and permeable monolith. The optimal preparation of monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, and thermogravimetric analysis. High efficiency and quick separation of alkylbenzenes, styrene and ethylbenzene, polycyclic aromatic hydrocarbon, phenols, anilines, and aromatic acids were achieved. The minimum plate height of this monolith were determined as 11.42 µm for thiourea and 13.26 µm for benzene. All results indicated that thiol-ene click chemistry provides a quick way for the fabrication of imidazolium-based monolith.

Differentiation of volatile aromatic isomers and structural elucidation of volatile compounds in essential oils by combination of HPLC separation and crystalline sponge method.

Structure elucidation of volatile aromatic isomers at trace level has long been considered as an elusive task, due to their structural similarities and similar polarities, even with the aid of many spectroscopic techniques such as mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. Single-crystal X-ray diffraction (SCD) is recognized as one of the most powerful structural elucidation techniques. The recently developed crystalline sponge method overcomes the intrinsic limitation of SCD that the target molecules must be single crystals, being able to analyze non-crystalline and trace-amount compounds without any special treatment. In order to investigate whether the crystalline sponge method could be used for the structure elucidation of closely related isomers or other volatile and even oily compounds in complex mixtures at trace level, we combined HPLC separation with the crystalline sponge method for X-ray crystallographic analysis. In this paper, two pairs of volatile aromatic isomers including cis/trans isomers of asarone and positional isomers of carvacrol and thymol, as well as the main volatile component in essential oil extracted from Acorus Tatarinowii, were first isolated by HPLC and encapsulated into the crystalline sponge then elucidated by X-ray crystallographic analysis. Direct observation of these volatile compounds by X-ray crystallography was achieved using only microgram quantities without crystallization or derivatization. Unambiguous identification of these compounds was realized without reference standards. This strategy offers a promising platform capable of providing high-confidence detailed structural information of closely related isomers as well as other volatile and even oily compounds in complex mixtures in microgram quantities.

Investigating strain dependency in the production of aromatic compounds in Saccharomyces cerevisiae.

Although Saccharomyces cerevisiae is the most highly domesticated yeast, strain dependency in biotechnological processes still remains as a common, yet poorly understood phenomenon. To investigate this, the entrance to the aromatic amino acid biosynthetic pathway was compared in four commonly used S. cerevisiae laboratory strains. The strains were engineered to accumulate shikimate by overexpressing a mutant version of the pentafunctional ARO1 enzyme with disrupted activity in the shikimate kinase subunit. Carbon tracing and 13 C metabolic flux analysis combined with quantitative PCR, revealed that precursor availability and shikimate production were dramatically different in the four equally engineered strains, which were found to be correlated with the strains' capacity to deal with protein overexpression burden. By implementing a strain-dependent approach, the genetic platform was reformulated, leading to an increase in yield and titer in all strains. The highest producing strain, INVSc1-SA3, produced 358 mg L-1 of shikimate with a yield of 17.9 mg g-1glucose. These results underline the importance of strain selection in developing biological manufacturing processes, demonstrate the first case of high production of shikimate in yeast, and provide an appropriate platform for strain selection for future production of aromatic compounds. Biotechnol. Bioeng. 2016;113: 2676-2685. © 2016 Wiley Periodicals, Inc.

Bioactive Secondary Metabolites with Unique Aromatic and Heterocyclic Structures Obtained from Terrestrial Actinomycetes Species.

Natural products from actinomycetes are important and valuable sources for drug discovery and the development of biological tools. The present review describes our recent study on the isolation of new natural products mainly possessing heterocyclic and aromatic ring structures with biological effects on cancer-related cellular pathways such as tumor necrosis factor-α-related apoptosis-inducing ligand (TRAIL) and Wnt signaling.

Application of nitrate to enhance biodegradation of gasoline components in soil by indigenous microorganisms under anoxic condition.

Anaerobic/anoxic biodegradation of hydrocarbons offers an attractive approach to the removal of these compounds from polluted environments such as aquifers, aquatic sediments, submerged soils and subsurface soils. The application of nitrate was investigated to accelerate the degradation of gasoline components such as mono-aromatic hydrocarbons and total petroleum hydrocarbons (TPH) in soil by indigenous microorganisms under anoxic condition. The addition of nitrate had little effect on the degradation of mono-aromatic hydrocarbons m- & p-xylene, o-xylene, sec-butylbenzene and 1,2,4-trimethylbenzene, but facilitated the degradation of TPH (C6-C12) and mono-aromatic hydrocarbons toluene and ethylbenzene markedly. Furthermore, the more nitrate added, the higher the percentage of toluene, ethylbenzene and TPH (C6-C12) degraded after 180 days of anoxic incubation. Microorganisms capable of degrading toluene, ethylbenzene and TPH (C6-C12) with nitrate as the electron acceptor under anaerobic/anoxic condition are composed predominantly of Alpha-, Beta-, Gamma- or Delta-proteobacteria. Beta- and Gamma-proteobacteria were the main components of indigenous microorganisms, and accounted for 83-100% of the total amount of indigenous microorganisms in soil used in this study. Furthermore, the total amount of indigenous microorganisms increased with nitrate added. The addition of nitrate stimulated the growth of indigenous microorganisms, and therefore facilitated the degradation of toluene, ethylbenzene and TPH (C6-C12).

Rejection of organic micro-pollutants from water by a tubular, hydrophilic pervaporative membrane designed for irrigation applications.

The links between chemical properties, including those relating to molecular size, solubility, hydrophobicity and vapour pressure, and rejection of model aromatic micro-pollutants by a tubular, hydrophilic polymer pervaporation membrane designed for irrigation applications were investigated. Open air experiments were conducted at room temperature for individual solutions of fluorene, naphthalene, phenol, 1,2-dichlorobenzene, 1,2-diethylbenzene and 2-phenoxyethanol. Percentage rejection generally increased with increased molecular size for the model micro-pollutants (47-86%). Molecular weight and log Kow had the strongest positive relationships with rejection, as demonstrated by respective correlation coefficients of r = 0.898 and 0.824. Rejection was also strongly negatively correlated with aqueous solubility and H-bond δ. However, properties which relate to vapour phase concentrations of the micro-pollutants were not well correlated with rejection. Thus, physicochemical separation processes, rather than vapour pressure, drive removal of aromatic contaminants by the investigated pervaporation tube. This expanded knowledge could be utilized in considering practical applications of pervaporative irrigation systems for treating organic-contaminated waters such as oilfield-produced waters.