JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Xue Xiong,Meiling Qi
This work describes the separation performance of utilizing hexagonal boron nitride (h-BN) as the stationary phase for capillary gas chromatography (GC). The statically coated h-BN column showed moderate polarity and achieved column efficiencies of 3455 plates/m and 3800 plates/m for naphthalene and n -dodecane, respectively. With temperature-dependent structure properties, the h-BN stationary phase exhibited stronger retention for polycyclic aromatic hydrocarbons (PAHs) over phthalic acid esters (PAEs) and showed advantageous separation performance over the g-C 3 N 4 and commercial polysiloxane stationary phases. Moreover, it displayed preferential retention for halogenated analytes and high resolution performance for structural and positional isomers. In addition, the h-BN column showed good column repeatability with relative standard deviation (RSD) values of 0.03%–0.07% for run-to-run, 0.31%–0.71% for day-to-day and 2.6%–5.3% for column-to-column, respectively, and thermal stability up to 260 °C.
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JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Qing Liu,Kevin Yan,Qiaomei Chen,Soumia Cheddah,Lin Shen,Han Xiao,Yan Wang,Chao Yan
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 SiO 2 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.
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JOURNAL OF CHROMATOGRAPHY A
·
2018
·
IF 3.716
Jing Li,Li Xu,Zhi-guo Shi
In this study, the ethyl-bridged hybrid silica microsphere with hierarchically meso-macroporous structure was initially synthesized through a method combining dispersion polymerization with sol-gel transition and phase separation. The flow-through macropores rendered the microsphere a rough surface like a waxberry, and thus the material was named as waxberry-like ethyl-bridged hybrid silica sphere (WEHS). WEHS was characteristic of appropriate alkali-stability, which was highly difficult for the pure silica. Additionally, WEHS possessed hierarchical meso- and macropores, which added additional value for faster mass transfer than the conventional fully porous silica materials. Taking the advantages of WEHS, it was successfully applied as the substrate to immobilize lipase; the prepared immobilized lipase exhibited high catalytic activity and favorable reusability under alkaline conditions, which was significant in pitch control of neutral-alkaline papermaking industry. Moreover, as the high-performance liquid chromatographic stationary phase matrix, WEHS made the separation under alkaline mobile phase into a reality for the silica-based materials. Besides, an ultra-fast and efficient separation in minutes was achieved with lower consumption of solvents and saving analytical time, which is highly desired in modern analysis. In general, WEHS was a novel and promising candidate in the myriads of silica-based materials.
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ANALYTICA CHIMICA ACTA
·
2015
·
IF 4.513
Juan Zheng,Kun Wang,Erlun Luo,Dingcai Wu,Fang Zhu,Ruifen Jiang,Chengyong Su,Chaohai Wei,Gangfeng Ouyang
The monodisperse microporous carbon nanospheres (MMCNSs) were applied in solid phase microextraction for the first time. The MMCNSs-fiber was prepared by sol–gel technique and good repeatability and reproducibility were obtained, due to the excellent monodispersity of the MMCNSs . The sol–gel-MMCNSs fiber exhibited superior extraction ability for polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs), compared with the commercial polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber and the fiber prepared with its precursor, the monodisperse microporous polystyrene nanospheres (MMPNSs). Moreover, the fiber has good thermostability and strong acid/base durability. The sol–gel-MMCNSs fiber was then employed to detect PAHs and OCPs in aqueous samples by combining with gas chromatography–mass spectrometer (GC–MS). Under the optimized conditions, the detection limits of the proposed method ranged from 0.10 to 5.5 ng L −1 . Furthermore, the method was successfully utilized for the analysis of PAHs and OCPs in real samples, with satisfactory recoveries in the range of 81.0–120% for the Pearl River water samples and 72.8–118% for the coking wastewater samples.
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JOURNAL OF CHROMATOGRAPHY A
·
2016
·
IF 3.926
Li-Hua Liu,Cheng-Xiong Yang,Xiu-Ping Yan
Covalent-organic frameworks (COFs) are a newfangled class of intriguing microporous materials. Considering their unique properties, COFs should be promising as packing materials for high performance liquid chromatography (HPLC). However, the irregular shape and sub-micrometer size of COFs synthesized via the traditional methods render the main obstacles for the application of COFs in HPLC. Herein, we report the preparation of methacrylate-bonded COF monolithic columns for HPLC to overcome the above obstacles. The prepared COF bonded monolithic columns not only show good homogeneity and permeability, but also give high column efficiency, good resolution and precision for HPLC separation of small molecules including polycyclic aromatic hydrocarbons, phenols, anilines, nonsteroidal anti-inflammatory drugs and benzothiophenes. Compared with the bare polymer monolithic column, the COF bonded monolithic columns show enhanced hydrophobic, π-π and hydrogen bond interactions in reverse phase HPLC. The results reveal the great potential of COF bonded monoliths for HPLC and COFs in separation sciences.
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ANALYTICA CHIMICA ACTA
·
2015
·
IF 4.513
Qing Wang,Mao Ye,Li Xu,Zhi-guo Shi
A mixed-mode chromatographic packing material, C18 and diol groups modified silica (C18-Diol), was prepared with controllable hydrophobicity and hydrophilicity . It demonstrated excellent aqueous compatibility and stability in aqueous mobile phase ; compared to the traditional C18 column, improved peak shape of basic analytes was also obtained. Additionally, it exhibited both reversed-phase liquid chromatographic (RPLC) and hydrophilic interaction chromatographic (HILIC) performance; the analyte separation scope was thus enlarged, demonstrated by simultaneous separation of twenty acids, bases and neutrals. More interestingly, a novel on-line two-dimensional liquid chromatography on the single column (2D-LC-1C) was established by modifying the high performance liquid chromatographic instrument only with the addition of an extra six-port two-position valve. The early co-eluted components of the extract of Lonicera japonica on the 1st-dimension (RPLC) were collected for the online re-injection to the 2nd-dimension (HILIC) by conveniently varying the mobile phase components. Six more peaks were obtained. The established system was simple, easy operation and low cost, which had advantages in analyzing complicated samples.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2017
·Vol. 409
·期 19
·4559-4569
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IF 3.431
Xu Jia,Li Yunfang,Li Cao,Zhang Rui,Xiao Yuxiu
A hexafluoroisopropanol (HFIP)-mediated cloud point extraction (CPE) system was established. A small amount of HFIP (even 1%, v / v ) can dramatically reduce the cloud point of Triton X-100 (TX-100) aqueous solution (even to 1 °C) and make liquid-liquid two-phase separation (coacervate phase and aqueous phase) occur at room temperature over a wide range of TX-100 concentration (0.5∼10%, g/mL). HFIP-mediated coacervate phase has smaller volume (volume ratio is 1.8∼8.9% relative to the volume of the total solution with 1∼5% TX-100) and larger micelle aggregates (30∼80 nm in diameter) compared to temperature-induced coacervate phase (volume ratio at 2.8∼14.0%, the diameter of micelle aggregates at 5∼30 nm). HFIP-mediated CPE was coupled to high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for the extraction and detection of organic pollutants in water, namely, polycyclic aromatic hydrocarbons (PAHs), fluoroquinolones (FQs), and sulfonamides (SAs) with different polarities, charges, and hydrogen-bonding properties. HFIP-mediated CPE provides much higher extraction rates (ERs) and enrichment factors (EFs) for FQs (91∼106%, 50∼59), PAHs (63∼90%, 33∼49), and SAs (26∼55%, 16∼34) compared with the temperature-induced one (ERs: 4∼8% for FQs, 25∼46% for PAHs, and 4∼37% for SAs; EFs: 1∼3 for FQs, 6∼12 for PAHs, and 8∼13 for SAs). The limit of detection ranges from 0.24 to 0.33 ng/mL for FQs, 0.04 to 0.38 ng/mL for PAHs, and 0.63 to 1.31 ng/mL for SAs. The proposed method was applied in the analysis of real water samples, and the recovery of 79.4∼110.8% and the relative standard deviation of 0.2∼16.3% were achieved for the three types of pollutants.
Schematic illustration of HFIP-mediated cloud point extraction
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PHYTOCHEMICAL ANALYSIS
·
2017
·Vol. 28
·期 4
·332-343
·
IF 2.292
Qing Wang,Yao Long,Lin Yao,Mao Ye,Li Xu
Introduction Traditional methods for isolating and purifying quaternary ammonium alkaloids from Coptis chinensis do not discriminate the target alkaloids from co-extractives. Mixed-mode analytical chromatography has the potential to improve the separation of analytes in more complex extracts and, when used in a solid-phase extraction mode, improve the purity of isolated compounds. Objective To examine the high-performance liquid chromatographic separation capabilities of a mixed-mode, silica-based adsorbent and its application to the purification of quaternary ammonium alkaloids from Coptis chinensis based on solid-phase extraction. Methodology The C18-COOH silica was prepared via “thiol-ene” click chemistry. Its chromatographic performance was firstly investigated. It was employed as the solid-phase extraction sorbent to purify quaternary ammonium alkaloids. Results Hydrophobic, attractive/repulsive electrostatic and ion-exchange interactions were demonstrated to be the possible retention mechanisms of a C18-COOH silica stationary phase, which could separate analytes of various properties. In addition, to purify quaternary ammonium alkaloids from Coptis chinensis, the solid-phase extraction approach based on the C18-COOH silica provided a slightly higher purification efficiency (6.7%) than an alkaloid-salt precipitation protocol (5.3%). The method had satisfactory reproducibility, re-using the same solid-phase extraction column three times, with relative standard deviations ranging from 1.99% to 8.02% for the six target alkaloids. Conclusion A multi-functionalised silica was synthesised via “click chemistry”. As the high-performance liquid chromatographic stationary phase, the C18-COOH silica could be operated in trimodal reversed-phase/weak cation exchange/hydrophilic interaction mode. The C18-COOH silica also exhibited potential as solid-phase extraction sorbent in the purification of quaternary ammonium alkaloids from complex matrices. Copyright © 2017 John Wiley & Sons, Ltd.
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JOURNAL OF CHROMATOGRAPHY A
·
2015
·
IF 4.169
Shu-Wen Xue,Min-Qiong Tang,Li Xu,Zhi-guo Shi
Magnetic nanoparticles (MNPs) featured with divinylbenzene (DVB) and sulfonate functionalities (Fe 3 O 4 –DVB–SO 3 − ) were prepared via “thiol-ene” click chemistry. The hydrophobic DVB moieties were dedicated for extraction while the hydrophilic sulfonate groups were designed for dispersing the MNPs in aqueous sample solution. Thus, the specially designed material could ensure operational convenience and improve reproducibility during extraction. The application of the material was demonstrated by the extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples followed by gas chromatography–mass spectrometric analysis. The main factors influencing the extraction, including the type of the desorption solvent, the agitation mode, the amount of MNPs, extraction and desorption time and salt addition in sample solution, were investigated in detail. Under the optimized conditions, the proposed method showed satisfactory reproducibility with intra-day and inter-day relative standard deviations less than 16.5% and 21.2%, and low limits of detection of 1.1 pg mL −1 , 0.8 pg mL −1 , 1.1 pg mL −1 , 1.4 pg mL −1 , 0.6 pg mL −1 , 2.1 pg mL −1 and 0.7 pg mL −1 for naphthalene, acenaphthene, fluorine, phenanthrene, anthracene, fluoranthene and pyrene, respectively. The developed method was also successfully used for determination of the PAHs in genuine lake and river environmental water samples by standard addition method. All the studied PAHs were detected in these waters with comparable results by the standard liquid–liquid extraction method. The developed MNPs with dual property of hydrophobicity and hydrophilicity were suitable for the treatment of water samples. The magnetic solid phase extraction based on this material was reliable and convenient. It has great potential in the preconcentration of trace analytes in complex matrix.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Jieyu Sui,Ruixuan Zhou,Kunyan Sui,Pengfei Qi,Wenxin Fan
The high-efficiency removal of harmful and persistent polycyclic aromatic hydrocarbon (PAH) pollutants from natural water is critical for safeguarding human health. A major challenge lies in the absence of effective technologies to accelerate the transfer of chemically inert and electroneutral PAHs from contaminated water to nano-adsorbents or nano-catalysts. Herein, we present a novel TiO 2 /polycation composite hydrogel membrane featuring dual gradients of positively charged groups and TiO 2 nano-catalysts for the deep and high-efficiency removal of PAH pollutants. The gradient polycation hydrogel matrix facilitates the spontaneous absorption of PAHs through cation-π interactions, while driving the directional migration of PAHs towards the high-density side via enthalpy-driven force induced by the positive charge gradient. Consequently, irradiating the high-density side of the dual-gradient composite hydrogel, enriched with PAHs and TiO 2 nano-catalysts, enables rapid and deep photocatalytic degradation of PAHs (e.g., naphthalene and phenanthrene). Furthermore, a mathematical model based on the Flory-Rehner theory is firstly developed to precisely control the distribution of PAHs within the composite hydrogels. Our findings provide a robust framework for the design of advanced composite catalysts with substantially enhanced removal efficiency for PAH pollutants.
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RENEWABLE ENERGY
·
2025
·
IF 9.1
Yingfu Tian,Tianliang Lu,Hongjin Qu,Xiaomei Yang,Lipeng Zhou
Efficient conversion of ethyl levulinate (EL) in high concentration to γ-valerolactone (GVL) at moderate temperature via catalytic transfer hydrogenation strategy is highly desirable. In this work, hydrothermally synthesized Sn-β zeolite with high Sn content was employed as a catalyst to realize this aim. Fully crystallized Sn-β zeolite with high Sn content ( n Si / n Sn = 60) was successfully synthesized within 12 days using MgCl 2 as a promoter. The synthesized zeolites were characterized by XRD, SEM, UV-vis spectroscopy, FT-IR spectroscopy and XPS. The L acid density of Mg-Sn-β-60-12d increased to 90 μmol g −1 compared to Mg-Sn-β-100-7d (56 μmol g −1 ). 92% yield of GVL was achieved on Mg-Sn-β-60-12d using high concentration of EL (1.2 mol L –1 ) as reactant at 130 o C for 8 h. The performance of Mg-Sn-β is better than that of Sn-β with same n Si / n Sn . The reaction mechanism over Mg-Sn-β was discussed. In addition, Mg-Sn-β-60-12d showed excellent stability and reusability during five runs.
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Food Chemistry-X
·
2025
·
IF 8.2
Xiaoying Li,Gang Li,Haijing Wang,Chunsheng Liu,Chunrui Rong,Fuhang Song,Caixia Chen,Junkai Wu
The changes in volatiles during postharvest storage of three peach cultivars (JC, ZYP9 and ZY8) were tracked under two temperature conditions (25 °C and 4 °C). Overall volatile content significantly decreased during storage over time, specifically with a marked decrease in ester levels, while the relative proportions of alcohols, aldehydes, and ketones increased during cold storage. These changes in volatile composition revealed three distinct storage stages across the cultivars, with the middle stage marking a critical turning point in volatile flavor quality. Among the cultivars, ZYP9 and ZY8 exhibited better adaptability to cold storage than JC. The reduction in key esters, coupled with the increase in alcohols and aldehydes, led to altered aroma profiles and the development of off-flavors in cold-stored peaches. Overall, this study provides valuable insights into the dynamic changes in flavor volatiles during postharvest storage and contribute to a deeper understanding of aroma quality in stored peaches.
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