CHROMATOGRAPHIA
·
2014
·Vol. 77
·期 19
·1379-1386
·
IF 1.37
Liu Huijun,Li Caixia,Wang Hong,Huang Zhongping,Zhang Peipei,Pan Zaifa,Wang Lili
Headspace solid-phase microextraction and gas chromatography/mass spectrometry (HS-SPME–GC/MS) method combined with XCMS Online was tentatively applied to characterize the dysregulated volatile organic metabolites (VOMs) in benign and malignant pleural effusions. A total of 9 dysregulated feature groups were isolated from metabolic features in 35 pleural effusion samples (20 benign effusions and 15 malignant ones from lung cancer patients). Principle component analysis, partial least squares discriminant analysis (PLS-DA) and orthogonal PLS-DA were built to separate benign from malignant pleural effusion groups and to find dysregulated metabolites in significantly different amounts between the two groups. Four dysregulated VOMs such as 2-ethyl-1-hexanol, cyclohexanone, 1,2,4,5-tetramethylbenzene and naphthalene were selected according to the variable influence on the projection value. The concentration of the four dysregulated VOMs in benign and malignant effusions were further determined by external standard method. The median concentrations of 4 VOMs in malignant effusion samples were from 4.7 to 91,121.9 nM, whereas their median levels were only 1.9–318.3 nM in benign ones. The results show that the proposed SPME–GC/MS-based metabolomic approach combined with XCMS Online data processing is a simple, rapid and available method for the characterization of dysregulated VOMs in malignant and benign pleural effusions.
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JOURNAL OF CHROMATOGRAPHIC SCIENCE
·
2013
·Vol. 52
·期 8
·932-937
·
IF 0.794
Liu Xiaofang,Zhou Shu,Zhu Quanfei,Ye Yong,Chen Huaixia
A sample pretreatment method, solid-phase extraction combined with dispersive liquid–liquid microextraction (SPE–DLLME), was established for the sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in smoked bacon samples. In the SPE–DLLME process, three PAHs including naphthalene (Naph), phenanthrene (Phen) and pyrene (Pyr) were extracted from samples and transferred into C18 SPE cartridge. The target analytes were subsequently eluted with 1.2 ml of acetonitrile–dichloromethane (5:1, v/v) mixture solution. The eluent was injected directly into the 5.0 ml ultrapure water in the subsequent DLLME procedure. The sedimented phase was concentrated under a gentle nitrogen flow to 120.0 µl. Finally, the analytes in the extraction solvent were determined by high-performance liquid chromatography with a ultra-violet detector. Some important extraction parameters affecting the performance, such as the sample solution flow rate, breakthrough volume, salt addition as well as the type and volume of the elution solvent were optimized. The developed method provided an ultra enrichment factors for PAHs ranged from 3478 to 3824. The method was applied for the selective extraction and sensitive determination of PAHs in smoked bacon samples. The limits of detection (S/N = 3) were 0.05, 0.01, 0.02 μg kg−1 for Naph, Phen, Pyr, respectively.
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JOURNAL OF CHROMATOGRAPHY A
·
2013
·
IF 4.612
Xingmei Guan,Chuande Zhao,Xiaoyan Liu,Haixia Zhang
A polymer monolith column was prepared using click chemistry for on-line solid phase microextraction of polycyclic aromatic hydrocarbons (PAHs), using 2,2′,7,7′-tetraethynyl-9,9′-spirobifluorene(TES) and 1,4-bis(6-azidoalkoxy)benzene (BAB) as monomers, and Cu(PPh 3 ) 3 Br as the catalyst. The polymer with spirocyclic cross-links was porous and presented an appropriate interspace of PAHs. Enrichment of PAHs, in the range of 100 to more than 1000 times, was due to the π – π stacking interaction and the effect of small size. The factors affecting the on-line microextraction efficiency were optimized, and the analytical conditions were evaluated to ensure reliability.
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TALANTA
·
2015
·
IF 3.545
Qing Wang,Yao Long,Lin Yao,Li Xu,Zhi-Guo Shi,Lanying Xu
A mixed-mode chromatographic stationary phase , C18-DTT (dithiothreitol) silica (SiO 2 ) was prepared through “thiol-ene” click chemistry. The obtained material was characterized by fourier transform infrared spectroscope, nitrogen adsorption analysis and contact angle analysis. Chromatographic performance of the C18-DTT was systemically evaluated by studying the effect of acetonitrile content, pH, buffer concentration of the mobile phase and column temperature. It was demonstrated that the novel stationary phase possessed reversed phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode property. The stop-flow test revealed that C18-DTT exhibited excellent compatibility with 100% aqueous mobile phase. Additionally, the stability and column-to-column reproducibility of the C18-DTT material were satisfactory, with relative standard deviations of retention factor of the tested analytes (verapamil, fenbufen , guanine , tetrandrine and nicotinic acid) in the range of 1.82–3.72% and 0.85–1.93%, respectively. Finally, the application of C18-DTT column was demonstrated in the separation of non-steroidal anti-inflammatory drugs, aromatic carboxylic acids , alkaloids, nucleo-analytes and polycyclic aromatic hydrocarbons . It had great resolving power in the analysis of various compounds in HILIC and RPLC chromatographic conditions and was a promising RPLC/HILIC mixed-mode stationary phase.
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JOURNAL OF SEPARATION SCIENCE
·
2015
·Vol. 38
·期 11
·1813-1821
·
IF 2.737
Qiaoxuan Zhang,Jialiang Guo,Yuan Xiao,Jacques Crommen,Zhengjin Jiang
To further evaluate the feasibility and applicability of the one-pot strategy in monolithic column preparation, two novel β-cyclodextrin-functionalized organic polymeric monoliths were prepared using two β-cyclodextrin derivatives, i.e. mono(6-amino-6-deoxy)-β-cyclodextrin and heptakis(6-amino-6-deoxy)-β-cyclodextrin. In this improved method, mono(6-amino-6-deoxy)-β-cyclodextrin or heptakis(6-amino-6-deoxy)-β-cyclodextrin reacted with glycidyl methacrylate to generate the corresponding functional monomers and were subsequently copolymerized with ethylene dimethacrylate. The polymerization conditions for both monoliths were carefully optimized to obtain satisfactory column performance with respect to column efficiency, reproducibility, permeability, and stability. The obtained poly(glycidyl methacrylate-mono(6-amino-6-deoxy)-β-cyclodextrin- co -ethylene dimethacrylate) and poly(glycidyl methacrylate-heptakis(6-amino-6-deoxy)-β-cyclodextrin- co -ethylene dimethacrylate) monoliths exhibited a uniform structure, good permeability, and mechanical stability as indicated by scanning electron microscopy and micro-high-performance liquid chromatography experimental results. Because of the probable existence of multi-glycidyl methacrylate linking spacers on the poly(glycidyl methacrylate-heptakis(6-amino-6-deoxy)-β-cyclodextrin- co -ethylene dimethacrylate) monolith, the effect of the ratio of glycidyl methacrylate/heptakis(6-amino-6-deoxy)-β-cyclodextrin was especially studied, and satisfactory reproducibility could still be achieved by strictly controlling the composition of the polymerization mixture. To investigate the effect of the degree of amino substitution of β-cyclodextrin on column performance, a detailed comparison of the two monoliths was also carried out using series of analytes including small peptides and chiral acids. It was found that the β-cyclodextrin-functionalized monolith with mono-glycidyl methacrylate linking spacers demonstrated better chiral separation performance than that with multi-glycidyl methacrylate linking spacers.
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Journal of the Taiwan Institute of Chemical Engineers
·
2015
·
IF 3
Xuemin Xiao,Dandan Liu,Yujun Yan,Zhilin Wu,Zhansheng Wu,Giancarlo Cravotto
Coal-based activated carbons (CAC) were prepared from coal in Xinjiang China by microwave-assisted activation. The effects of preparation conditions on adsorption capabilities of CAC for methylene blue (MB) and iodine were investigated. The microwave activation was carried out with coal activator ratio of 1:3 for 12 min at 700 W of power, the adsorption capacities of the prepared CAC achieved the maximal values of 312 and 1048.19 mg/g for MB and iodine. The increasing of CAR, activation time, and microwave power reduced the surface functional groups and improved the pH PZC of CAC. The BET surface area and total pore volume of CAC prepared were identified as 1770.49 m 2 /g and 0.99 cm 3 /g, respectively. Hence, the work demonstrates that the use of microwave heating for preparing CAC is more rapid, cheaper and efficient. The adsorption behaviors of typical polycyclic aromatic hydrocarbons (PAHs) in ethanol aqueous solution on CAC were also explored. Equilibrium data were favorably described by the Langmuir and Freundlich isotherms, and adsorption kinetics was fitted to the pseudo-second-order model well. The equilibrium adsorption amounts were 117.17 mg/g for pyrene, 111.39 mg/g for phenanthrene, and 78.18 mg/g for naphthalene. Thus, CAC prepared by microwave activation could have a very effective application in removal of these PAHs.
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TALANTA
·
2014
·
IF 3.511
Guijiang Zhang,Xiaohuan Zang,Zhi Li,Chun Wang,Zhi Wang
In this study, polydimethylsiloxane/metal-organic frameworks (PDMS/MOFs), including PDMS/MIL-101 and PDMS/MOF-199, were immobilized onto a stainless steel wire through sol–gel technique as solid-phase microextraction (SPME) fiber coating. The prepared fibers were used for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. Under the optimized experiment conditions, the PDMS/MIL-101 coated fiber exhibited higher extraction efficiency towards PAHs than that of PDMS/MOF-199. Several parameters affecting the extraction of PAHs by SPME with PDMS/MIL-101 fiber, including the extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. The limits of detection (LODs) were less than 4.0 ng L −1 and the linearity was observed in the range from 0.01 to 2.0 µg L −1 with the correlation coefficients ( r ) ranging from 0.9940 to 0.9986. The recoveries of the method for the PAHs from water samples at spiking levels of 0.05 and 0.2 µg L −1 ranged from 78.2% to 110.3%. Single fiber repeatability and fiber-to-fiber reproducibility were less than 9.3% and 13.8%, respectively.
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Scientific Reports
·
2017
·Vol. 7
·期 1
·1-11
·
IF 4.259
Huang Haiying,Tao Xuanyu,Jiang Yiming,Khan Aman,Wu Qi,Yu Xuan,Wu Dan,Chen Yong,Ling Zhenmin,Liu Pu,Li Xiangkai
Soil contamination by PAH and heavy metals is a growing problem. Here, we showed that a new isolate, Pseudomonas brassicacearum strain LZ-4, can simultaneously degrade 98% of 6 mM naphthalene and reduce 92.4% of 500 μM hexavalent chromium [Cr (VI)] within 68 h. A draft genome sequence of strain LZ-4 (6,219,082 bp) revealed all the genes in the naphthalene catabolic pathway and some known Cr (VI) reductases. Interestingly, genes encoding naphthalene pathway components were upregulated in the presence of Cr (VI), and Cr (VI) reduction was elevated in the presence of naphthalene. We cloned and expressed these naphthalene catabolic genes and tested for Cr (VI) reduction, and found that NahG reduced 79% of 100 μM Cr (VI) in 5 minutes. Additionally, an nahG deletion mutant lost 52% of its Cr (VI) reduction ability compared to that of the wild-type strain. As nahG encodes a salicylate hydroxylase with flavin adenine dinucleotide (FAD) as a cofactor for electron transfer, Cr (VI) could obtain electrons from NADH through NahG-associated FAD. To the best of our knowledge, this is the first report of a protein involved in a PAH-degradation pathway that can reduce heavy metals, which provides new insights into heavy metal-PAH contamination remediation.
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JOURNAL OF CHROMATOGRAPHY A
·
2017
·
IF 3.981
Xingru Hu,Chao Liu,Jiansheng Li,Rui Luo,Hui Jiang,Xiuyun Sun,Jinyou Shen,Weiqing Han,Lianjun Wang
In this study, a novel hollow mesoporous carbon spheres-based fiber (HMCSs-F) was fabricated to immobilize HMCSs onto a stainless steel wire for solid-phase microextraction (SPME). Characterization results showed that the HMCSs-F possessed a large specific surface area, high porosity and uniform pore size. To demonstrate the extraction performance, a series of polycyclic aromatic hydrocarbons (PAHs) was chosen as target analytes. The experimental parameters including extraction and desorption conditions were optimized. Compared to commercial fibers, the HMCSs-F exhibited better extraction efficiency for PAHs. More interestingly, a good extraction selectivity for PAHs from the complex matrix was observed in these HMCSs-F. The enhanced SPME performance was attributed to the unique pore structure and special surface properties of the HMCSs. Furthermore, under the optimum conditions, the limits of detection (LODs) for the HMCSs-F were in the range of 0.20–1.15 ng L −1 with a corresponding relative standard deviation that was below 8.6%. The method was successfully applied for the analysis of PAHs in actual environmental water samples with recoveries ranging from 85.9% to 112.2%. These results imply that the novel HMCSs-F have potential application in environmental water analysis.
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JOURNAL OF CHROMATOGRAPHY A
·
2017
·
IF 3.981
Chengjiang Zhang,Xialin Luo,Tianfu Wei,Yufei Hu,Gongke Li,Zhuomin Zhang
A new dynamic covalent polymer (DCP) gel was well designed and constructed based on imine chemistry. Polycondensation of 4,4′-biphenyldicarboxaldehyde and 1,3,5-benzenetricarbohydrazide via Schiff-base reaction resulted in an acylhydrazone bond gel (AB-gel) DCP. AB-gel DCP had three-dimensional network of interconnected nanoparticles with hierarchically porous structure. AB-gel DCP was successfully fabricated as a monolithic column by an in-situ chemical bonding method for online enrichment and separation purpose with excellent permeability. AB-gel DCP based monolithic column showed remarkable adsorption affinity towards target analytes including sulfonamides (SAs) and fluorescent whitening agents (FWAs) due to its strong π-π affinity, hydrophobic effect and hydrogen bonding interaction. Then, AB-gel DCP based monolithic column was applied for online separation and analysis of trace SAs and FWAs in food samples coupled with high-performance liquid chromatography (HPLC). Sulfathiazole (ST) and sulfadimidine (SM2) in one positive weever sample were actually found and determined with concentrations of 273.8 and 286.3 μg/kg, respectively. 2,5-Bis(5- tert -butyl-2-benzoxazolyl) thiophene (FWA184) was actually quantified in one tea infusion sample with the concentration of 268.5 ng/L. The spiked experiments suggested the good recoveries in range of 74.5–110% for SAs in weever and shrimp samples with relative standard deviations (RSDs) less than 9.7% and in range of 74.0-113% for FWAs in milk and tea infusion samples with RSDs less than 9.0%. AB-gel DCP monolithic column was proved to be a promising sample preparation medium for online separation and analysis of trace analytes in food samples with complex matrices.
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NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 11
·4637-4643
·
IF 3.269
Bing Yu,Hongbo Zhang,Hailin Cong,Chuantao Gu,Lilong Gao,Bo Yang,Muhammad Usman
Porous poly(glycidylmethacrylate-co-divinylbenzene) (PGMA-co-DVB) microspheres with an average size of 4.6 μm were prepared using a multistage emulsion polymerization method successfully and were subsequently modified by diazoresin (DR). Three kinds of porogens (toluene, cyclohexanol and dodecanol) were applied and porous microspheres with different morphologies were obtained. Porous PGMA–DVB microspheres resulting from toluene were selected for further modification with DR due to their large specific surface area and good pore structure. These microspheres were modified through the hydrolysis of epoxy groups and a photocuring reaction with DR. After treatment with UV light, the hydrogen bonding between hydrolyzed microspheres and DR was converted into covalent bonding through a unique photochemistry reaction of DR. Porous PGMA–DVB–DR microspheres were used as the stationary phase for high performance liquid chromatography (HPLC). Depending on the chemical structure of DR, the DR modified PGMA–DVB stationary phase can be used to perform mix-mode separation mechanisms, including reversed phase (RP) and hydrophilic interactions. Therefore, baseline separation of benzene analogs was achieved by using the porous PGMA–DVB–DR particles as packing materials, and the by-product of hydrophilic acetic acid was rapidly separated from the N-vinyl-1,2,4-triazole product within 5 minutes. In addition, the DR-modified particles may be expected to be an alternative tool for organic acid separation due to the presence of secondary amino groups.
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TALANTA
·
2016
·
IF 4.035
Jialiang Guo,Yuan Xiao,Yuanjing Lin,Qiaoxuan Zhang,Yiqun Chang,Jacques Crommen,Zhengjin Jiang
In order to investigate the effect of the linking spacer on the enantioseparation ability of β -cyclodextrin ( β -CD) functionalized polymeric monoliths, three β -CD-functionalized organic polymeric monoliths with different spacer lengths were prepared by using three amino- β -CDs, i.e. mono-6-amino-6-deoxy- β -CD, mono-6-ethylenediamine-6-deoxy- β -CD, mono-6-hexamethylenediamine-6-deoxy- β -CD, as starting materials. These amino- β -CDs reacted with glycidyl methacrylate to produce functional monomers which were then copolymerized with ethylene dimethacrylate. The enantioseparation ability of the three monoliths was evaluated using 14 chiral acidic compounds, including mandelic acid derivatives, nonsteroidal anti-inflammatory drugs, N -derivatized amino acids , and chiral herbicides under optimum chromatographic conditions. Notably, the poly(GMA-NH 2 - β -CD- co -EDMA) column provides higher enantioresolution and enantioselectivity than the poly(GMA-EDA- β -CD- co -EDMA) and poly(GMA-HDA- β -CD- co -EDMA) columns for most tested chiral analytes. Furthermore, the enantioseparation performance of triazole-linker containing monoliths was compared to that of ethylenediamine-linker containing monoliths. The results indicate that the enantioselectivity of β -CD monolithic columns is strongly related to the length and type of spacer tethering β -CD to the polymeric support .
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