FOOD CHEMISTRY
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2023
·
IF 8.8
Haiyue Yuan,Bei Li,Jing Wei,Xiaowei Liu,Zeying He
In this study, multi-residue analysis methods for 32 pyrethroids in fruit and vegetable samples were established in both GC–MS/MS and UHPLC-MS/MS. The parameters that affecting the ionization efficiencies of pyrethroids in UHPLC-ESI-MS/MS, including ion source temperature, in-source fragmentation, and mobile phase conditions were thoroughly investigated to guarantee better performance. These two techniques were comprehensively compared in terms of recovery, LOQ, linearity, and matrix effects. In general, UHPLC-MS/MS was found suitable for more pesticides than GC–MS/MS. Lower LOQs were obtained for most of the selected pyrethroids in UHPLC-MS/MS. Similar results were obtained in terms of recoveries and RSDs for the validated pesticides in fortification experiments. A total of 136 real samples were analyzed by both techniques, obtaining similar results. The results suggest that UHPLC-MS/MS offers a suitable alternative to GC–MS/MS in the routine analysis of pyrethroids in fruits and vegetables.
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Journal of Physical Chemistry C
·
2023
·
IF 3.7
Nian Wei,Kuangmin Zhao,Zhiyou Zhou,Yu-Cheng Wang,Shi-Gang Sun
The effect of porosity on the interface microenvironment and catalytic performance of carbon dioxide reduction reaction (CO2RR) is still unclear for iron- and nitrogen-doped carbon-based (Fe/N/C) materials, and previous studies mainly focus on aqueous electrode test conditions rather than a practical working environment. Herein, several Fe/N/C-based catalysts with very different pore structures were prepared and compared to understand how the surface area and micropores affect the CO2RR between aqueous electrode test and practical working conditions with a solid–gas–liquid triple-phase boundary. The apparent current density correlates positively to the surface area in both test conditions. The onset current density where hydrogen evolution reaction starts is irrelevant to the micropore fraction in the aqueous electrode test but correlates negatively to the micropore fraction in a practical working condition. The inconsistency is attributed to different reaction interfaces in both cases, resulting in different interface microenvironments in different pore size ranges. This work helps in designing porous electrocatalysts for CO2RR or beyond.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Shenyao Wang,Mingjie Pan,Kaili Wang,Lili Jiang,Han Tao,Zhenyu Zhao,Guiling Shi,Wenjun Lin,Haoran Li,Congmin Wang
Careless emission of nitric oxide (NO), primarily from the post-combustion flue gas of fossil fuel, has resulted in severe environmental pollution and posed significant health risks to human beings. In the meantime, NO is an important intermediate in manufacturing nitric acid and nitro chemicals, where the preparation of NO has contributed to great energy consumption. Therefore, establishing a green and low-cost denitrification method to achieve the efficient conversion of NO in flue gas to nitric acid and nitro chemicals is of great significance. For this purpose, the novel strategy that applies functionalized ionic liquids to converting ultralow-concentration NO in the presence of air and water under elevated pressure is proposed, which incorporates the positive influence of elevated pressure on absorption and conversion of NO, efficient chemisorption ability and good catalytic performance of functionalized ionic liquids, and the elimination effect of water for nitrogen dioxide. Based on this strategy, the high cleanup efficiency of 96.1% for 500 ppm of NO in the realistic flue gas is achieved by the functionalized ionic liquid containing 40% water at 30 °C and 1 MPa, and nitrogen oxides concentration of the exhaust gas is only 19.6 ppm (about 28 mg Nm–3) that meets the stringent regulation of cleanup emission of nitrogen oxides (lower than 50 mg Nm–3). In addition, the presence of 750 ppm of sulfur dioxide and 5–10% water, which may deactivate the absorbents and catalysts, does not suppress the denitrification performance of the ionic liquid. Finally, the cleanup efficiency of the ionic liquid for 500 ppm of NO maintains at about 96.2% during 5 cycles with no traces of decomposition products. We believe that this sustainable strategy will open new prospects for cleanup and circular utilization of NO in industrial flue gas.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Xiang Li,Xueqian Wang,Langlang Wang,Li Yuan,Yixing Ma,Yibing Xie,Yiran Xiong,Ping Ning
The low S selectivity of catalysts for H 2 S removal significantly hinders its application in blast furnace gas desulfurization. In this study, Cu-based coconut shell biochar was modified with different types and contents of alkali species. The results showed that the S selectivity close to 100% was prolonged from 0 to 750 min. At the same time, the sulfur capacity was increased from 242.1 mg/g (before the modification) to 373.4 mg/g by using K 2 CO 3 -induced Cu-based biochar at 120 °C. In CO, H 2 O, and O 2 atmosphere, H 2 S was dissociated and oxidized to elemental S. Additionally, K 2 CO 3 exhibited an elemental S anchoring effect, making the S more stable at medium–high temperatures and weakening the reactivity of S with CO and ·O 2 – . Thus, less COS and SO 2 were generated. Moreover, the basic sites enhanced by K 2 CO 3 promoted the hydrolysis of COS to generate H 2 S, which entered the desulfurization cycle. K 2 CO 3 also showed a synergistic effect with the active components, generating more ·O 2 – to promote the oxygenation of H 2 S. The regeneration efficiency of the catalyst could be stabilized above 90%. These findings could provide guidance and reference for designing and applying desulfurization catalysts with high S selectivity and activity.
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JOURNAL OF CHROMATOGRAPHY A
·
2022
·
IF 4.601
Leikeqing Shen,Jiayang Zhang,Xueping Dang,Huaixia Chen,Hongmei Yuan
The zirconium metal-organic framework (MOF) UiO-66 was modified by dopamine (DA) and electrodeposited with Poly (3,4-ethylenedioxothiophene) (PEDOT) on an etched stainless steel wire to prepare a UiO-66-DA/PEDOT nanocomposite coating. The coating was characterized by scanning electron microscopy, energy dispersive spectrometer, Fourier transform infrared and thermogravimetric analysis, respectively. The coating has high specific surface area and more porous structure, which can be used to extract eight phenols, including 2-chlorophenol, o-cresol, m-cresol, 2, 4-dichlorophenol, 4-tert-butylphenol, 4-chlorophenol, 4-tert-octylphenol and α-naphthol. The adsorption behavior of the phenols on the UiO-66-DA/PEDOT coating had significant correlation with Langmuir isothermal model. A determination method for the eight phenols was established by combining with direct immersion solid-phase micro extraction and gas chromatography. Under the optimal experimental conditions, the detection linear range (LRs) was 0.05–50 μg mL −1 and the detection limit (LODs) was 0.01–0.08 μg mL −1 (S/ N = 3). The method was applied for the migration detection of eight phenols in polycarbonate cups, which showed satisfactory recovery.
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高影响因子
CRYSTENGCOMM
·
2023
·Vol. 25
·期 44
·6215-6224
·
IF 3.1
Yong Song,Zhiyuan Jin,Jiawei Zhang,Bo Jin,Rufang Peng
In this work, we report a spiral gas–solid two-phase flow (S-GSF) method based on spiral jet mills for the continuous mechanochemical preparation of urea co-crystals for the first time. Urea–adipic acid (UAA), urea–catechol (URCAT), urea–salicylic acid (USA) and urea–gypsum (URCASU) co-crystals were prepared to demonstrate the feasibility of this approach. The prepared products were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The results showed that powdered products of the urea co-crystals can be obtained continuously by using this method without the addition of any solvent in the preparation process. Moreover, the UAA co-crystal prepared by S-GSF is in single polycrystalline form I, while form II, which appears in milling and ball milling, is not observed. The transcrystallization behavior among different polymorphs of the UAA co-crystal was studied and their thermodynamic stability was investigated by theoretical calculations. The results indicated that form I is a thermodynamically stable polymorph, and S-GSF is selective for the formation of form I. This phenomenon can be attributed to the fact that S-GSF provides strong mechanical action, as well as a low-temperature reaction environment, which distinguishes it from existing mechanochemical methods.
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Journal of Analytical Methods in Chemistry
·
2021
·
IF 2.193
Ling Yu,Guiquan Guo,Jun Zhao,Linnan Zhao,Aiqing Xia,Xu He,Cuijuan Xing,Lili Dong,Fang Wang
A fast method based on Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) modified QuEChERS integrated to dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry was established for the determination of 8 organochlorine pesticides (OCPs) in green leafy vegetables. The factors involved in the purification by QuEChERS and concentration by DLLME were optimized. In the QuEChERS process, Fe3O4 MNPs were used as a new impurity adsorbent after the sample extraction procedure by acetonitrile, which achieved phase separation rapidly. Carbon black was used as an alternative to costly graphitized carbon black without affecting the recovery. In the process of DLLME, 1 mL of the extract obtained by QuEChERS was used as the dispersive solvent, 40 μL of chloroform was used as the extractive solvent, and 4 mL of water was added. Making them mix well, then the dispersed liquid-liquid microextraction concentration was subsequently carried out. The enrichment factors of 8 OCPs ranged from 22.8 to 36.6. The recoveries of the proposed method ranged from 78.6% to 107.7%, and the relative standard deviations were not more than 7.5%. The limits of detection and limits of quantification were 0.15–0.32 μg/kg and 0.45–0.96 μg/kg, respectively. The method has been successfully applied to the determination of OCPs in green leafy vegetable samples.
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MICROCHEMICAL JOURNAL
·
2021
·
IF 4.821
Yuge Hou,Xiaofei Jiang,Yuhang Gao,Ying Li,Wensi Huang,Hong Chen,Xiaoyu Tang,Makoto Tsunoda,Jinyu Li,Yingxia Zhang,Xi Xie,Rong Wang,Wenting Hu,Yanting Song,Lushuang Li
Type II pyrethroids has been reported to possess significant toxicity. The analysis of type II pyrethroid residues in biological samples for clinical monitoring and toxicological studies will be favorable. However, due to the interference caused by complex matrix and the trace amount of the pyrethroids, the analysis remains difficult. This study details an efficient method employing magnetic molecularly imprinted polymers as a magnetic solid-phase extraction adsorbent coupled with gas chromatography-mass spectrometry for the detection of type II pyrethroids in human plasma. Molecular simulations were used to screen a suitable monomer and ratio of monomer to template molecule. A series of functional nanoparticles were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy and vibrating sample magnetometer to verify the coating of functional groups. Then, a binding experiment was employed to evaluate the adsorption properties. According to the results of isotherm study, the adsorption sites and capacity of MMIPs are much better than MNIPs, while the maximum adsorption capacity of magnetic molecular imprinted polymers is 27.115 mg g −1 . The solid phase extraction conditions were investigated, including eluent type, amount of eluent, extraction time and magnetic molecular imprinted polymers amount. The chromatographic separation of type II pyrethroids in human plasma was carried out by Gas Chromatography-Mass Spectrometry; Linearity was assessed using curves prepared with pyrethroids concentrations of 0.2, 1, 2, 5, 10, 25, 50 ng mL −1 ; the coefficients of determination were more than 0.990, and the recoveries are within the range of 90.0 and 100.1%. The limits of detection of four pyrethroid pesticides were between 0.005 and 0.032 ng mL −1 ; The relative standard deviation of magnetic molecular imprinted polymers were 2.74–4.07%. It was confirmed that the current analytical approach can be applied for the selective determination of type II pyrethroids in human plasma samples or other complex matrices.
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APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Pengcheng Wang,Jun Liu,Peiwen Xu,Xinzhen Feng,Weijie Ji
Three morphologically uniform γ-Al 2 O 3 crystallites [Al 2 O 3 hexagonal plates (Al 2 O 3 -HP), stacked hexagonal plates (Al 2 O 3 -SHP) and rods (Al 2 O 3 -R)] were controllably synthesized. The Co-Mo oxide precursor was loaded on these γ-Al 2 O 3 substrates via aqueous incipient wetness impregnation and transformed to the sulfides under 10% H 2 S/H 2 (v/v) atmosphere. The mainly exposed facet of Al 2 O 3 -HP and Al 2 O 3 -SHP was identified to be the (1 1 0) and (1 0 0)/(1 1 1), respectively; whereas a polycrystalline structure was observed over Al 2 O 3 -R. The original structural feature of oxide precursors, i.e., 2D polymeric/monomeric as well as 3D polymeric/MoO 3 species substantially varied over Al 2 O 3 -HP, Al 2 O 3 -SHP, and Al 2 O 3 -R, which in turn determines the effectiveness in sulfidation of surface oxide precursors. The richness of MoS 2 /Co 9 S 8 /Co-Mo-S species, and less fraction of partially sulphurated CoMoO x S 2 as well as CoO x /SO x 2− entities were recognized over Al 2 O 3 -HP. Based on the areal activity at 250 °C, the sulfides-Al 2 O 3 (1 1 0) interface is approximately 6–13.8 times more active than the poly-crystalline or commercial γ-Al 2 O 3 supported sulfides for water gas shift (WGS) in a hydrogen-rich stream. The sulfides-Al 2 O 3 (1 1 0) interface also notably outperformed the sulfides-Al 2 O 3 (1 0 0)/(1 1 1) interfaces for the reaction.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Wei Cai,Yixin Hu,Ying Pan,Xia Zhou,Fukai Chu,Longfei Han,Xiaowei Mu,Zeyuan Zhuang,Xin Wang,Weiyi Xing
As one of emerging layered nanomaterials, the potential of black phosphorous nanosheets (BP) for fabricating high performance polymer composites was seriously confined by incompatible interface. Herein, interfacial engineering between BP nanosheets and polyurethane (PU) matrix was rationally designed, where employing polymerized ionic liquid as linking bridge between robust BP nanosheets and soft TPU. The ionic liquid (IL) was firstly confined onto the surface of BP nanosheets with the combination of electrostatic-driving self-assembly process and in situ radical polymerization was then performed. The successful preparation of IL-functionalized BP (IL-BP) nanosheets was confirmed by a series of analytic methods, incluing TEM, XPS, FTIR, and so on. The resultant IL-BP nanosheets imparted well mechanical performance and flame retardancy to TPU composites. Compared to the mechanical enhancement reported by other literatures, the break strength of TPU/IL-BP-1.0 was significantly increased by 50%, attributing to strong interfacial regulation of polymerized IL and mechanically robust BP nanosheets, generated by the similar polarity. Meanwhile, significant decreases of 38.2% and 19.7% in peak values of heat release rate and total heat release were achieved for TPU/IL-BP-2.0. With the investigation of combustion residue and pyrolysis products, it was found that a mass of pyrolysis products reacted with IL-BP nanosheets to form mechanically robust protective char and solid products, being no longer used as fuel to support combustion. Meanwhile, the maximum concentration of CO 2 and highly toxic CO of TPU/IL-BP-2.0 were effectively decreased by 36.9% and 26.5%, compared to the pure TPU. Such a design route effectively regulates the interfacial interaction between BP nanosheets and polymer matrix and offers a practical route for preparing high performance materials.
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FOOD RESEARCH INTERNATIONAL
·
2018
·
IF 3.52
Chengying Ma,Junxing Li,Wei Chen,Wenwen Wang,Dandan Qi,Shi Pang,Aiqing Miao
Oolong tea is a typical semi-fermented tea and is famous for its unique aroma. The aim of this study was to compare the volatile compounds during manufacturing process to reveal the formation of aroma. In this paper, a method was developed based on head-space solid phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC–MS) combined with chemometrics to assess volatile profiles during manufacturing process (fresh leaves, sun-withered leaves, rocked leaves and leaves after de-enzyming). A total of 24 aroma compounds showing significant differences during manufacturing process were identified. Subsequently, according to these aroma compounds, principal component analysis and hierarchical cluster analysis showed that the four samples were clearly distinguished from each other, which suggested that the 24 identified volatile compounds can represent the changes of volatile compounds during the four steps. Additionally, sun-withering, rocking and de-enzyming can influence the variations of volatile compounds in different degree, and we found the changes of volatile compounds in withering step were less than other two manufacturing process, indicating that the characteristic volatile compounds of oolong tea might be mainly formed in rocking stage by biological reactions and de-enzyming stage through thermal chemical transformations rather than withering stage. This study suggested that HS-SPME/GC–MS combined with chemometrics methods is accurate, sensitive, fast and ideal for rapid routine analysis of the aroma compounds changes in oolong teas during manufacturing processing.
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JOURNAL OF CHROMATOGRAPHY A
·
2013
·
IF 4.612
Zhanqi Gao,Yuehua Deng,Xiaobin Hu,Shaogui Yang,Cheng Sun,Huan He
A simple, low-cost and sensitive method for determining organophosphate esters (OPEs) in water samples has been developed based on headspace solid-phase microextraction (SPME) followed by gas chromatography-flame photometric detector. The ionic liquid (1-allyl-3-methylimidazolium tetrafluoroborate, [AMIM][BF 4 ])-based coating was developed by sol–gel technology and employed for extracting analytes. The prepared coating performed stably at high temperatures (up to 335 °C) and with a range of solvents. It can be used at least 200 times without an obvious decrease in extraction efficiency. The extraction capability of the new fiber was much higher than polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polyacrylate (PA) fibers. The experimental parameters that influenced the extraction efficiency, including extraction time, extraction temperature, stirring rate and ionic strength were investigated and optimized. Under the optimal conditions, the method detection limits (S/N = 3) were in the range of 0.7–12 ng L −1 , and the limits of quantification (S/N = 10) were between 1.0 and 28 ng L −1 . The repeatability of a single fiber varied from 3.3 to 7.6% (intra-day precision, n = 6) and 4.3 to 8.9% (inter-day precision, n = 6). The reproducibility of fiber-to-fiber ( n = 6) was in the range of 3.1–9.4%. The proposed method was applied successfully for the determination of OPEs in lake water, wastewater, sewage treatment plant effluent, and tap water with recoveries varying from 75.2 to 101.8%. The results demonstrate that the proposed method is highly effective for analyzing OPEs in water samples.
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