JOURNAL OF MASS SPECTROMETRY
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2019
·Vol. 54
·期 3
·239-249
·
IF 2.267
Hua-Ming Xiao,Xian Wang,Xing Yang,Feng Zheng,Yu-Qi Feng
Hydralazine has been widely employed in the development of drugs, derivatization reagents, and ligands. In the present work, we reported a new type of dehydrogenated ion [M − H] + that was produced from the hydralazine derivative of hexanal in electrospray ionization mass spectrometry (ESI-MS). The formation of [M − H] + ions in the ESI-MS was found to be independent on the mobile phase composition of the liquid chromatography and ESI source parameters. A series of hydralazine derivatives of aldehyde were investigated to confirm this phenomenon. The results showed that hydralazine derivatives of aldehydes that contained an sp 3 hybridization carbon with a hydrogen at the α-position of aldehydes could form the unexpected [M − H] + ions, whereas hydralazine derivative of acetone could only generate [M + H] + ion in the ESI-MS. We proposed the possible formation mechanism of [M − H] + ion for the hydralazine derivatives of aldehydes: the [M − H] + ion was possibly formed by the loss a hydrogen molecule (H 2 ) from the protonated ion [M + H] + . The results obtained from density functional theory (DFT) calculations supported this proposed formation mechanism of [M − H] + ion.
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ANALYTICA CHIMICA ACTA
·
2019
·
IF 5.256
Hui Ma,Christian Marcus Pedersen,Qi Zhao,Zexiang Lyu,Hui Chang,Yan Qiao,Xianglin Hou,Yingxiong Wang
The Fischer–Tropsch (FT) process is a practical approach to convert synthesis gas (CO and H 2 ) into hydrocarbons and oxygenates, and these product mixtures are usually well-characterized. However, the analysis of Fischer–Tropsch waste water (FTW) is still somewhat underdeveloped and the exact composition of FTW remains unclear. Herein, various qualitative NMR techniques, especially diffusion-ordered spectroscopy (DOSY) and one dimension (1D) selective gradient total correlation spectroscopy (SelTOCSY) were strategically applied in the analysis of FTW. The NMR results show that the DOSY technique can pseudo-separate most of components in complex mixtures over the diffusion dimension. The SelTOCSY technique is used as a supporting method in the cases where the DOSY technique cannot clearly distinguish overlapped signals. Moreover, the quantitative 1 H NMR (qNMR) was further used to quantify the components of the sample. These routine and advanced qualitative and quantitative NMR technique utilized here provide a fast, effective and feasible method for the identification of complex mixtures in FTW, which might be a powerful and fast alternative to gas chromatography or high performance liquid chromatography for FTW research.
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CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
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2019
·
IF 0.931
Ming LI,Jing-Ye CHEN,Yu-Fei HU,Gong-Ke LI
By using nano TiO 2 -Y 2 O 3 as catalyst, cataluminescence (CTL) phenomenon of propylene oxide (PO) was studied, and it was found that the sensor has high sensitivity and good selectivity for the detection of propylene oxide. The common volatile organic compounds (VOCs) such as acetone, acetaldehyde and benzene show no response to the catalysis of TiO 2 -Y 2 O 3 . Based on this phenomenon, a propylene oxide CTL sensor was designed. The ratio of TiO 2 and Y 2 O 3 and the annealed temperatures of the composites were optimized. It was found that when the mass ratio of TiO 2 and Y 2 O 3 was 1:3 and the annealed temperature was 500 °C, the catalytic materials showed the best performance. 0.3 L min −1 of carrier gas flow rate, 490 nm of detection wavelength and 197 °C of working temperature were selected as the optimal working conditions, and under the optimized conditions, the quantitative analysis was performed and CTL intensity was linearly correlated with PO concentration from 4.5 mg L –1 to 1375 mg L –1 with a detection limit (3σ) of 1.25 mg L –1 . The sensor was used for quantitative analysis and real-time monitoring of propylene oxide residues in fumigation cereals. The result was consistent with that analyzed by gas chromatography. The CTL sensor proposed here had many merits such as high sensitivity, rapidity and simple operation and had potential application prospects in the rapid detection of propylene oxide in food. At last, the mechanism of catalytic oxidation of PO was discussed as well.
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JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES
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2019
·
IF 2.813
Quan Wang,Xinyue Zhou,Qian Li,Pan Zhao,Yanxia Ren,Tong Jiang,Shigang Shen
A novel ferrocene-based monolith with a network structure was fabricated via in situ free radical polymerization using vinyl ferrocene as the co-monomer within a stainless-steel column (50 × 4.6 mm i.d.) for the separation of proteins from complex bio-samples, taking merit of the specific absorption of ferrocene to protein, including human plasma, egg white, and standard proteins. The morphology and pore size distribution indicate that the optimized monolith has a relatively uniform structure with the network. The results showed that 26 fractions were separated from human plasma, and the column efficiency of the aromatic small molecule , naphthalene , was up to 30,560 plates m −1 . The homemade monolith showed excellent selectivity for intact proteins, mainly depending on the hydrophobic chromatography mechanism of ferrocene. In addition, the electrostatic interaction and hydrogen-bond interaction were the additional interactions in the chromatographic separation owing to the sandwich structure of ferrocene present in the monolithic column.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Guangying He,Jinhui Zhang,Yun Hu,Zhaogao Bai,Chaohai Wei
Mesoporous TiO 2 nanotubes (m-TiO 2 -NTs) with outstanding photocatalytic performance have been successfully synthesized, for the first time, through a dual-template method. The dual-template method uses multi-walled carbon nanotube (CNT) as a hard template to control the morphology and cetyltrimethylammonium bromide (CTAB) as a soft template to form the mesoporous structure. The resulting m-TiO 2 -NTs are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), nitrogen adsorption-desorption and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) and dibutyl phthalate (DBP) are used as model pollutants to evaluate the photocatalytic properties of the new materials. The m-TiO 2 -NTs possess a multiple channel tubular structure and have higher specific surface area than TiO 2 nanoparticles (TiO 2 -NPs). These features result in significantly superior photocatalytic activity for photodegradation. Specifically, the reaction rate constant for the photodegradation of RhB is 9.8 times greater with m-TiO 2 -NTs than it is with TiO 2 -NPs. In the case of DBP, the rate constant is 7.7 times higher. Photocatalytic removal ratios of gaseous acetaldehyde (CH 3 CHO) and the generation of CO x (CO + CO 2 ) were detected to evaluate the decomposition ability of the materials, m-TiO 2 -NTs showed the best CH 3 CHO removal efficiency and the highest CO 2 selectivity. The active species of photocatalytic process are found to be OH. In addition, the m-TiO 2 -NTs exhibit excellent thermal and photocatalytic stability even after six recycles. This work demonstrates a novel way to fabricate mesoporous TiO 2 nanotubes that have multiple channel tubular structure and to apply them in environmental photocatalysis.
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ACS Catalysis
·
2019
·
IF 12.221
Liu Yang,Tingting Yan,Chuanming Wang,Weili Dai,Guangjun Wu,Michael Hunger,Weibin Fan,Zaiku Xie,Naijia Guan,Landong Li
The formation of the initial carbon–carbon (C–C) bonds in the methanol-to-hydrocarbon (MTH) conversion on acidic zeolite has been hotly debated for decades. Recently, the formation of surface-bound acetyl groups involving C–C bonds during the initial period of the MTH conversion has been disclosed. Understanding the exact C–C bond-containing intermediates triggering the MTH conversion and the critical roadmap of the MTH conversion is essential for the further development of this important reaction. Herein, acetaldehyde from the hydrogenation of surface-bound acetyl species was identified to be responsible for triggering the MTH conversion on H-ZSM-5 zeolite. By combining kinetic studies, spectroscopic analyses, and theoretical calculations, the mechanism and roadmap of zeolite-catalyzed MTH conversion from the initial C–C bonds to the hydrocarbon pool compounds were clearly depicted.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Yeqing Wang,Jian Zhang,Xiangju Meng,Shichao Han,Qiuyan Zhu,Na Sheng,Liang Wang,Feng-Shou Xiao
In this work, we show sustainable and efficient synthesis of nanosized EMT zeolite under organotemplate-free and solvent-free conditions, which not only completely avoids the use of organic templates for production of NOx and CO 2 but also effectively reduces the formation of polluted water. In addition, the yield of EMT zeolite is significantly enhanced by this route, compared with conventional hydrothermal synthesis . The nanosized EMT zeolite obtained has good crystallinity, uniform crystal size distribution, and high surface area. Ion-exchange tests show that the nanosized EMT zeolite owes high Ca 2+ and Mg 2+ ion exchange capacity at room temperature, which is potentially important for softening hard water in the industrial processes. Catalytic tests in Knoevenagel condensation show that the nanosized EMT zeolite exhibits higher activity than that of the EMT zeolite synthesized using organic template, indicating the importance of the nanosized EMT zeolite as a base catalyst.
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MOLECULES
·
2019
·Vol. 24
·期 23
·4275
·
IF 3.06
Qian-Chun Zhang,Wu-Li Yan,Li Jiang,Yu-Guo Zheng,Jing-Xin Wang,Run-Kun Zhang
In this work, we successfully developed a novel and sensitive gas sensor for the determination of trace acetophenone based on its cataluminescence (CTL) emission on the surface of nano-praseodymium oxide (nano-Pr6O11). The effects of working conditions such as temperature, flow rate, and detecting wavelength on the CTL sensing were investigated in detail. Under the optimized conditions, the sensor exhibited linear response to the acetophenone in the range of 15–280 mg/m3(2.8–52 ppm), with a correlation coefficient (R2) of 0.9968 and a limit of detection (S/N = 3) of 4 mg/m3(0.7 ppm). The selectivity of the sensor was also investigated, no or weak response to other compounds, such as alcohols (methanol, ethanol,n-propanol,iso-propanol,n-butanol), aldehyde (formaldehyde and acetaldehyde), benzenes (toluene,o-xylene,m-xylene,p-xylene),n-pentane, ethyl acetate, ammonia, carbon monoxide, carbon dioxide. Finally, the present sensor was applied to the determination of acetophenone in human exhaled breath samples. The results showed that the sensor has promising application in clinical breath analysis.Keywords:cataluminescence;sensor;acetophenone;Pr6O11
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Xingang Li,Rui Wang,Yutao Yan,Runnan Zhao,Hong Li,Xin Gao
EG is an important industrial raw material, and the hydrolysis of 2-ethyl-1,3-dioxolane (2ED) to re-obtain EG is a very important step to recover EG from an EG and 1,2-BDO azeotropic mixture via a reversible-reaction-assisted intensification process. The applicability of reactive distillation for 2ED hydrolysis in the presence of KRD-002 ion exchange is studied by experiments and simulations. The reaction kinetics were investigated, and the kinetic parameters were derived. Thermodynamic aspects of the reaction system were discussed, and the NRTL model was built. Pilot-plant reactive distillation experiments were performed using the structured catalytic packing unit (SCPI) with several operating condition variations (reflux ratio (RR), feed mole ratio (FMR), and feed-in style). The experimental results are in good agreement with the simulation results, which prove that the equilibrium stage model can describe the hydrolysis experiments quantitatively. The simulation was subsequently used to determine the influence of important design factors and laid the foundation for industrial application.
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NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 11
·9140-9150
·
IF 3.201
Jiliang Ma,Xinwen Peng,Linxin Zhong,Runcang Sun
The application of biomass-based carbonaceous solid acids in catalysis is attracting increasing attention in the field of chemistry. In this study, a heterogeneous carbon-based solid acid biocatalyst (CXH-SO3H) with regular spherical structure was synthesized from xylan-type hemicellulose (XH) by a simple two-step method. The catalyst was successfully applied in the synthesis of O- and N-heterocycles with yields of 80–99% and 60–97%, respectively. In view of environment and economy, CXH-SO3H shows the merits of environmental friendliness, easy operation, simple work-up, excellent yields, and the avoidance of use of organic solvents and expensive catalysts. Moreover, the as-synthesized solid acid catalyst could be used for several cycles without significant loss in its catalytic activity. The results of FT-IR, XRD, and SEM showed that no distinct differences in physico-chemical structures of CXH-SO3H were observed. Thus, the eco-friendly CXH-SO3H catalyst is a promising candidate for green synthesis of O- and N-heterocycles from low-cost feed-stocks and has good prospect in partially substituting commercially available solid and liquid acid catalysts and precious metal catalysts.
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TALANTA
·
2018
·
IF 4.244
Liu Chen,Yu-Jia Fu,Wen-Le Fang,Xiao-Feng Guo,Hong Wang
Carbonyl compounds are widely distributed in organisms, and the commonly used methods for determination of them like UV/fluorescence/mass spectrometry always require derivatization reagents. However, the reported derivatization reagents have significant difference in reactivity, which is very unfavorable for developing highly reactive reagent. In this study, we theoretically investigated the factors affecting the reactivity of hydrazine-based derivatization reagents, and proposed a strategy for filtering highly reactive reagents by quantum chemical calculation . With this strategy, N-propyl-4-hydrazino-1,8-naphthalimide (NPHNA) was filtered out as a fluorescent derivatization reagent. Taking aliphatic aldehydes as representatives, we evaluated the reactivity of NPHNA for carbonyl compounds. The derivatization of NPHNA with aliphatic aldehydes could be finished at room temperature within 60 min or 35 °C within 35 min, which showed higher reactivity than the most popular UV/MS reagent, 2,4-dinitrophenylhydrazine (DNPH). We believe that the strategy we proposed in this work is of great potential to design highly reactive UV/fluorescent/MS labeling reagents for carbonyl compounds and even other analytes.
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RSC Advances
·
2018
·Vol. 8
·期 59
·34069-34077
·
IF 2.936
Minhua Zhang,Xuechao Tan,Tong Zhang,Zheng Han,Haoxi Jiang
A deactivation study on the ethanol/acetaldehyde conversion to 1,3-butadiene over a ZnO promoted ZrO2–SiO2 catalyst prepared by a sol–gel method was performed. The samples were characterized by N2 adsorption–desorption isotherms, scanning electron microscopy (SEM), NH3 temperature programmed desorption (NH3-TPD), X-ray powder diffraction characterization (XRD), thermogravimetric analyses (TGA), Fourier transform infrared resonance (FT-IR), 13C magic-angle spinning nuclear magnetic resonance (13C NMR) and X-ray photoelectron spectroscopy (XPS). The pore structure characteristics and surface acidity of Zn0.5–Zr–Si catalysts were largely decreased with time-on-stream and no crystal structure was formed in the used catalyst, indicating that the deactivation was caused by carbon deposition. Two main types of carbon deposition were formed, namely low-temperature carbon deposition with the oxidation temperature of around 400 °C and high-temperature carbon deposition with the oxidation temperature of 526 °C. The carbon species were mainly composed of graphitized carbon, amorphous carbon, carbon in C–O bonds and carbonyls. The deactivated catalyst could be regenerated by a simple oxidation process in air. Adding a certain amount of water into the feed had a positive effect on reducing the carbon deposition.
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