INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2021
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IF 3.764
Luo Wu,Rui Zhang,Yaning Zhang,Haiyan Liu,Zhichang Liu,Chunming Xu,Xianghai Meng
Aluminum species in AlCl3–arene and AlCl3–CuCl–arene solutions (including benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene) were investigated using 27Al NMR and infrared (IR) spectroscopy. The AlCl3·arene and Al2Cl6·arene complexes were demonstrated experimentally. AlCl3 could not coordinate with benzene and toluene at a low temperature (40 °C) but could form complexes at a high temperature (80 °C). AlCl3 could coordinate with xylene and mesitylene to form Al2Cl6·arene complexes at both low and high temperatures (40 and 80 °C). As for AlCl3–CuCl–arene solutions with a molar ratio of 1:1:2, two signals were observed in 27Al NMR spectra. The signal at around 101 ppm was assigned to CuAlCl4·2arene complexes, and the other signal at around 96 ppm belonged to AlCl3·arene complexes. The characteristic peaks of AlCl3–CuCl–arene solutions in IR spectra moved toward the low field due to the strong π-back-bonding. The CuAlCl4·2arene complexes would convert to CuAl2Cl7·2arene complexes with a further increase in AlCl3 content when the molar ratio of AlCl3/CuCl exceeded 1. The synthesis mechanism of AlCl3–CuCl–arene solutions was analyzed by in situ Fourier transform IR (FTIR) spectroscopy. Three reaction pathways originating from different aluminum species were proposed.
研究领域:
化学
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材料科学
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Food Analytical Methods
·
2019
·Vol. 12
·期 4
·991-997
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IF 2.413
Li Yunyan,Mao Wenping,Liu Chaoyang,Zhang Xu,Wang Junfeng
We propose a J -selective quantitative distortionless enhancement by polarization transfer ( J -selective QDEPT) 13 C NMR method with enhanced sensitivity for accurate determination of the fatty acid compositions of edible oils. The J -selective QDEPT protocol is developed by targeted optimization of the known Q-DEPT + experiment. Based on the one-bond C-H J -coupling constants ( 1 J CH ) which can be measured with the heteronuclear two-dimensional J -resolved 13 C NMR spectrum, it is possible to optimize the polarization transfer delay Δ and the reading pulse angle ⊖ , thus enabling the QDEPT experiment further enhancing 13 C resonance signals which have narrow 1 J CH ranges over the traditional untargeted Q-DEPT. For edible oil applications, it is demonstrated that this procedure brings a 2.2 enhancement factor against 1.3 of the traditional untargeted Q-DEPT compared to the standard inverse-gated 13 C experiment, even with a shorter relaxation delay for the two QDEPT experiments. Another advantage of J -selective QDEPT is that a smaller number of quantitative scans are needed to reach a uniform enhancement for different CH n ( n = 1, 2, 3) groups. These features of the J -selective QDEPT are particularly attractive for batch analysis in the food industry.
研究领域:
食品科学
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分析化学
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生物化学
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RAPID COMMUNICATIONS IN MASS SPECTROMETRY
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2022
·Vol. 36
·期 20
·e9358
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IF 2.586
Donghai Xu,Fangfang Pan,Hao Ruan,Nan Sun
Rationale Hydroxychloroquine sulfate is effective in the treatment of malaria and autoimmune diseases and as an antiviral drug. However, unreported impurities are often detected in this drug, which pose a health risk. In this study, the structures of hydroxychloroquine and six unknown impurities were analyzed using ultra-high-performance liquid chromatography-quadrupole/time-of-flight-tandem mass spectrometry (UHPLCQ/TOF/MS/MS), and the structures were characterized using liquid chromatography-solid-phase extraction-nuclear magnetic resonance (LC-SPE-NMR) spectroscopy. Methods An Agilent InfinityLad Poroshell HPH-C18 column (100 × 4.6 mm, 2.7 μm) was used. For the analysis of hydroxychloroquine and six unknown impurities, the mobile phase was 20 mM ammonium formate aqueous solution and methanol/acetonitrile (80:20, v/v) using gradient elution. Full-scan MS and MS 2 were performed to obtain as much structural information as possible. In addition, six unknown impurities were separated by semipreparative liquid chromatography and characterized using LC-SPE-NMR. Results The MS 2 fragmentation patterns of the impurities were investigated, leading to more structural information and an understanding of the fragmentation pathways of the impurities. The structures of the unknown impurities were confirmed using NMR. In addition, some possible pathways of the formation of the impurities in the drugs were outlined, and these impurities were found to be process impurities. Conclusions Based on the identification and characterization of these impurities, this study also describes the cause of the production of the impurities and provides insights for companies to improve their production processes and a scientific basis for the improvement of the related pharmacopoeias.
研究领域:
药学
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分析化学
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医学
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DOI
PubMed
高影响因子
FOOD RESEARCH INTERNATIONAL
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2023
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IF 8.1
Wenjiang Dong,Qidi Hong,Jinhuan Cheng,Hongyan He,Yanan Li,Rongsuo Hu,Yuzhou Long
Green coffee oil (GCO) extracted from green coffee beans, is known for its antioxidant and anticancer properties, and has been increasingly utilised in cosmetic and other consumer products. However, lipid oxidation of GCO fatty acid components during storage may be harmful to human health, and there remains a need to understand the evolution of GCO chemical component oxidation. In this study, proton nuclear magnetic resonance ( 1 H and 13 C NMR) spectroscopy was used to investigate the oxidation status of solvent-extracted and cold-pressed GCO under accelerated storage conditions. Results show that the signal intensity of oxidation products gradually increased with increasing oxidation time, while unsaturated fatty acid signals gradually weakened. Five different types of GCO extracts were clustered according to their properties, except for minor overlapping in the two-dimensional plane of the principal component analysis. Partial least squares-least analysis results demonstrate that oxidation products ( δ = 7.8–10.3 ppm), unsaturated fatty acids ( δ = 5.28–5.42 ppm), and linoleic acid ( δ = 2.70–2.85 ppm) in 1 H NMR can be used as characteristic indicators of GCO oxidation levels. Furthermore, the kinetics curves of unsaturated fatty acids, linoleic, and linolenic acyl groups all fit an exponential equation with high coefficients of GCO for 36 days under accelerated storage conditions. Our results show that the current NMR system is a fast, easy-operated and convenient tool for the oxidation process monitoring and quality control of GCO.
研究领域:
食品科学
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分析化学
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PubMed
高影响因子
Gas Science and Engineering
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2023
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IF 0
Rui Zhang,Haonan Liu,Ruixi Liu,Yingjie Niu,Luning Yang,Francesco Barzagli,Chao'en Li,Min Xiao
The blending of primary amines, with fast reaction kinetic, together with tertiary amines, with a large loading capacity, is an increasingly popular approach to develop high-performance CO 2 capture sorbents with low energy requirements for regeneration. In this study, we investigated the CO 2 absorption performance of several aqueous solutions obtained by mixing ethanolamine (MEA) and diethylethanolamine (DEEA) and compared them with that of individual MEA and DEEA. CO 2 loadings at equilibrium were measured experimentally under a wide range of operating conditions, at temperatures between 298 and 323 K, CO 2 partial pressures in the range 5–60 kPa, and different amine mixing ratios. In addition, 13 C NMR spectroscopy was employed to elucidate the reaction mechanisms and identify the species formed during CO 2 capture. The results of the study reveal the intricate interplay of MEA and DEEA in CO 2 capture, where MEA carbamate formation predominates in the early stages, gradually shifting to bicarbonate formation as the amine concentration decreases. Moreover, excess properties, which reflect non-ideal behaviors in amine blends, were introduced as a key parameter in the study. An excess property model, based on excess CO 2 loading, was developed to accurately predict the CO 2 equilibrium solubility without constant experimental measurement. As a result, good agreement was found between the experimental data and those calculated with the model (excess CO 2 loading) under the same operating conditions, with a average relative deviation of 1.1%.
研究领域:
化学工程
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环境科学
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SEPARATION AND PURIFICATION TECHNOLOGY
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2024
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IF 8.1
Haonan Liu,Francesco Barzagli,Li Luo,Xin Zhou,Jiaofei Geng,Chao’en Li,Min Xiao,Rui Zhang
The combination of primary and tertiary amines represents a promising approach to improve sorbent performance in CO 2 capture by enhancing absorption efficiency and reducing regeneration energy. This study focuses on investigating the absorption performance of binary mixtures of ethanolamine (MEA) and N,N-dimethylethanolamine (DMEA) at temperatures between 298–323 K and CO 2 partial pressures between 5–60 kPa. The species generated during the absorption were analyzed using 13 C NMR spectroscopy, to clarify the intricate role of MEA and DMEA in the capture process. A developed excess property model for MEA-DMEA, based on excess CO 2 loading, predicted equilibrium CO 2 solubility data with an average absolute relative deviation (AARD) of 1.6 %. Additionally, the machine learning models XGBoost, RBFNN, and SVR were applied, providing AARD values between 0.86 % and 1.28 %, demonstrating strong agreement between experimental and predicted outcomes. These comprehensive findings enhance our understanding of mixed amines’ mechanisms and practical applications, contributing to ongoing research development.
研究领域:
化学工程
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环境科学
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机器学习
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ENERGY & FUELS
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2024
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IF 5.2
Ying Xu,Dong Wang,Xin Wang,Jian Dong
The rapid growth of natural gas clathrate hydrate has been a significant safety hazard in off-shore natural gas drilling and gas transport. Alleviation of hydrate formation can be achieved by applying low-dosage hydrate inhibitors of polymers during operation. In order to combine the advantages of high adsorption potential and environmental friendliness, we study the kinetics of hydrate inhibition of amphiphilic highly branched poly(l-lysine) (PLL) by NMR relaxometry. The introduction of n-butyl and cyclohexyl groups in PLLs was found to be significantly effective in prolonging the induction times of sII clathrate hydrates. Key physical–chemical factors involved in the mechanism previously proposed by molecular dynamics simulations can be clarified by NMR relaxometry. Induction times for the formation of hydrate are associated with the interfacial water amount but are not related to the hydrogen bonding strength or dynamics of the free water component. The amphiphilic PLLs in the interface interact with the hydrate surfaces through their hydration shell. Analysis of the molecular motion and freezing kinetics of water in the fluid before and during hydrate formation reveals that the polymers can reduce the rates of hydrate growth from the free water by a factor of 5 to 10. A further significant decrease in the growth rates from small hydrate particles by a factor of 10 to 2600 was observed in the presence of the amphiphilic PLLs with n-butyl and cyclohexyl groups. The distinct crystal growth kinetics in the heterogeneous interface are influenced by the terminal alkyl groups of the polymers, with changing growth geometry or crystal shapes and consistent with the interfacial Gibbs–Thomson effect. A high Avrami index value of the isothermal crystal growth and nonfreezable water amount favors a long induction time. The PLL inhibitors adsorb to the hydrate surface and act via an interfacial mechanism.
研究领域:
化学工程
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材料科学
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环境科学
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高影响因子
JOURNAL OF SOLUTION CHEMISTRY
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2018
·Vol. 47
·期 4
·705-714
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IF 1.401
Li Qiang,Liu Bijun,Mu Wanjun,Yu Qianhong,Tian Yin,Liu Guoping,Yang Yuchuan,Li Xingliang,Luo Shunzhong
Glufosinate, an analogue of glutamic acid (also known as phosphinothricin), is an important herbicide. The protonation constants of glufosinate were determined by means of potentiometric titrations at variable temperatures with ionic strength 0.5 mol·L −1 (NaCl solution). The heat effects of the protonation reactions of glufosinate were measured by direct calorimetry. NMR spectroscopies have demonstrated that the first protonation site occurs on the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and crystal structure results. These data will help to predict the speciation of glufosinate in physiological systems.
研究领域:
植物学
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化学
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环境科学
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高影响因子
ANALYTICA CHIMICA ACTA
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2022
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IF 6.911
Biling Huang,Lihua Xu,Jianxi Ying,Yufen Zhao,Shaohua Huang
Chiral carboxylic acids are ubiquitous in nature and are of pivotal importance in practical applications in the field of food science and pharmaceuticals. Simultaneous enantiomeric analysis of carboxylic acids mixtures is a significant research goal. Herein, we demonstrate a new strategy involving the use of the highly selective chiral derivatizing agent ( R )-2-amino-1,1,1-trifluoropropane (( R )-TFPA) for the enantiomeric discrimination and selective identification of carboxylic acids in mixtures, even structurally similar drugs. The key success of this sensing approach lies in the distinguishable 19 F NMR signals of diastereoisomers formed via derivatization of the substrates by ( R )-TFPA. The utility of this approach was demonstrated by simultaneously differentiating 20 chiral carboxylic acids in a complicated mixture with accurate determination of the enantiomeric excess ( ee ). Most importantly, our approach can be applied to food analysis, where the diverse carboxylic acids in real samples without separation were unambiguously identified, such as vinegar , yogurt, and grape.
研究领域:
食品科学
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药物化学
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分析化学
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DOI
PubMed
高影响因子
Magnetic Resonance Letters
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2026
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IF 1.7
Ying Yang,Biling Huang,Qiong Wang,Guangjin Hou,Shaohua Huang
NMR spectral simplification is a powerful strategy for facilitating the analysis and structural characterization of complex mixtures. In this work, we present a nanoparticle-assisted protocol that employs positively charged imidazolium ionic liquid-coated silica nanoparticles ( 1 ) to selectively interact with analytes. π-π interactions, electrostatic attractions, and hydrogen-bonding between the nanoparticles and target molecules extend the rotational correlation time, thereby accelerating relaxation processes. As a result, NMR signals from aromatic and negatively charged species undergo pronounced attenuation or even complete disappearance. In contrast, signals from positively charged analytes or compounds lacking π-bond systems remain largely unaffected. This selective suppression of resonances enables effective spectral simplification and highlights the potential of nanoparticle-based editing approaches for practical applications in the analysis and structural determination of complex mixtures.
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Scientific Reports
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2025
·Vol. 15
·期 1
·1-16
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IF 3.9
Logrado Millena,Gaddam Anuraag,Zhuo Fangping,Zhao Changhao,Gao Shuang,Breitzke Hergen,Rosenstihl Markus,Vogel Michael,Rödel Jürgen,Buntkowsky Gerd
Thermal treatments play a crucial role in tuning the functional properties of lithium-based perovskites, which are of interest for applications in energy storage, actuation and sensing. In the present work, the impact of aging and quenching on the local structure and lithium mobility in lithium sodium niobate (LNN) ceramics was investigated using Density Functional Theory (DFT), transmission electron microscopy (TEM) and solid-state Nuclear Magnetic Resonance (NMR) techniques. Our results demonstrate that quenching inhibits the formation of a lithium-rich phase, leading to significant modifications in dipolar and quadrupolar interactions. Aging induces the formation of LiNbO 3 within the perovskite matrix, with no indication of lithium mobility at the boundaries of LiNbO 3 grains. The presence of multiple lithium environments in aged samples was indicated by transmission electron microscopy and confirmed through 7 Li Magic Angle Spinning (MAS) NMR, revealing distinct structural differences between aged and unaged samples. NMR parameters were also compared with parameters calculated by Density Functional Theory. The findings suggest the formation of LiNbO 3 and an additional lithium poor phase in aged LNN samples. These results indicate that the quenching effect reduces dipolar interactions and considerably sharpens the 7 Li NMR spectra, while structural modifications induced by thermal processing affect lithium ordering, providing new insights into the phase behavior of LNN ceramics.
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JOURNAL OF MOLECULAR LIQUIDS
·
2018
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IF 4.513
Mengjie Wu,Wei Zhou,Christian Marcus Pedersen,Hui Ma,Yan Qiao,Xiaoya Guo,Xianglin Hou,Yingxiong Wang
As counter parts of ILs , DESs have received general interest because of their comparable physicochemical properties to ILs and facile preparation from readily available chemicals. In this work, the isomeric distributions of fructose, glucose, xylose and GlcNAc in CCU, CCG and CCO , i.e. basic, neutral and acidic DES, have been determined by 13 C NMR. Higher furanose fraction of fructose was observed in CCO compared to CCG and CCU. The glucose was chosen as model compound to reveal the effect of DES on the mutarotation behavior with DMSO‑ d 6 as co-solvents. The experimental results showed that a high ratio of CCU to glucose speed up the mutarotation rate of glucose in DMSO‑ d 6 , but have little influence on the anomeric distribution. Furthermore, the mutarotation of glucose in DESs is mainly driven by the HBD , whereas HBA provides little influence. However, HBD and HBA display a synergistic effect on the glucose mutarotation process. Hydrogen bonding between hydrogen of amino in urea and oxygen of hydroxyl in glucose is the driving force for the interconversion of anomers.
研究领域:
化学
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物理化学
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分析化学
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高影响因子
危险品化学品经营许可证（带存储）