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排序方式: 共有265条查询结果,搜索用时 31 毫秒
61.
62.
Sheau‐Long Lee Chung‐Min Yang Kuan‐Jiunn Shieh Xinmiao Liang Hai‐Yan Li 《中国化学会会志》2000,47(6):1247-1249
Better peak shapes and complete separation of amino‐3,5‐dinitro derivatives by (S)‐N‐(2‐naphthyl)alanine derived chiral stationary phase (CSP) is achieved by adding a trace amount of acetic acid in the mobile phase. This method provides an indication of its broad applicability on direct separation of a series of amino‐containing enantiomers on CSP. In addition, the reversed elution order was obtained on its enatiomeric CSP. 相似文献
63.
Monodisperse phenylene-bridged organosilica spheres show great potential as chromatographic stationary phase. In this paper, the tunable particle size of monodisperse phenylene-bridged organosilica spheres were prepared by co-condensing different proportion of 1,4-bis(triethoxysilyl)benzene (1,4-BTEB) and tetraethylorthosilicate (TEOS), and then pore size was expanded by two-step post-synthesis hydrothermal treatments using N,N-dimethyldecylamine (DMDA)/dodecylamine (DDA) and tris-(hydroxymethyl)-aminomethane (TRIS) in turn. Phenylene-bridged organosilica spheres with particle size of 3.0-3.5 μm and pore size of 85 Å were further surface modified by C18 group and tested in reversed-phase high performance liquid chromatography (RP-HPLC). The primary chromatographic results demonstrated that C18 bonded phenylene-bridged organosilica stationary phase has high retention and good chemical stability in the high pH mobile phase, which indicated that the phenylene-bridged organosilica can be used for HPLC packing supports. 相似文献
64.
Wang Yanping Zhang Feifang Xue Xingya Xiao Yuansheng Feng Jiatao Liang Xinmiao 《Chromatographia》2009,69(11):1379-1384
The reliability of evaluation of compound purity depends on the analytical method selected. A suitable analytical method, including the modes of separation and detection, can provide reliable information about compound purity. Effective separation is the key to achieving precise results. In this work we developed a novel method, based on an orthogonal system, RP-LC-hydrophilic interaction liquid chromatography, for evaluating the purity of compounds isolated by preparative reversed-phase liquid chromatography. Because of its good orthogonality, good separation and more accurate assessment of compound purity could be achieved.
相似文献65.
Jing Zhang Yu Jin Yanfang Liu Yuansheng Xiao Jiatao Feng Xingya Xue Xiuli Zhang Xinmiao Liang 《Journal of separation science》2009,32(12):2084-2089
An effective method utilizing the same RP chromatographic column with different pH in first and second LC dimensions has been developed for separation of the basic compounds from traditional Chinese medicines (TCMs). In this work, the alkaloids in Corydalis yanhusuo which is an important TCM were selected as a model to develop the method. The additives and pH values of the mobile phase were optimized in this work. To investigate the feasibility of this method, off-line mode separation was performed in the experiments. According to the UV-absorption intensity, there were eight fractions collected in acidic conditions. All the fractions were analyzed in basic conditions. The results showed that the chromatographic selectivities were significantly different in the separations performed with acidic and alkaline elution systems. Complementary separation was achieved in this work. It is demonstrated that this method would be an effective tool for alkaloids research. Based on the different pH of the mobile phase in this method, it could also be suitable to analyze compounds which were sensible to the pH of the solution. 相似文献
66.
Aijin Shen Weijia Zhou Lele Xiong Hongli Jin Long Yu Huimin Wu Wenyi Yu Dongping Yu Zhimou Guo Yanfang Liu Xinmiao Liang 《Journal of separation science》2022,45(6):1162-1169
Qingfei Paidu Decoction is a Chinese medicine formula that has been proved effective in the treatment of coronavirus disease 2019. However, the comprehensive separation and characterization of Qingfei Paidu Decoction are of a great challenge due to the diversity of chemical components in a wide range of polarity. In this study, a triplex off-line two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry is developed for the analysis of Qingfei Paidu Decoction. One reversed-phase liquid chromatography×hydrophilic interaction liquid chromatography system and two reversed-phase liquid chromatography×reversed phase liquid chromatography systems were constructed to separate polar components and weak-polar components in Qingfei Paidu Decoction, respectively. Benefiting from the good orthogonality of two-dimensional liquid chromatography and high sensitivity of quadrupole time-of-flight MS, chemical components with different polarities and content were discovered. A total of 749 peaks were detected in positive and negative ionization mode and presented as a four-dimensional data plot. Meanwhile, 498 compounds belonging to 14 categories were tentatively identified. These results provide good supplementary to elucidate the material basis of Qingfei Paidu Decoction. The triplex off-line two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry strategy can be a powerful and efficient tool for the separation and characterization of chemical substances in traditional Chinese medicine formulas. 相似文献
67.
Xiaoming Cai Jun Dong Yuanyuan Wang Xingya Xue Xinmiao Liang 《Analytica chimica acta》2009,650(1):10-15
Highly polar metabolites are abundant in human plasma. Analysis of these compounds by standard reverse-phase chromatography is difficult. Highly polar metabolites were extracted by a two-step method. They were analyzed by ultra-performance hydrophilic interaction chromatography (HILIC) coupled to quadrupole-time of flight mass spectrometer detection technology. The middle and low polar fraction were also analyzed using a standard C18 column. Data were extracted by Markerlynx, and analyzed by multivariate statistical methods to discriminate human plasma samples by sex and age. The results not only showed good classification of samples by sex and age, but also revealed new potential biomarkers not revealed by standard RPLC/MS analysis. This study showed that HILIC is an effective technique to analyze highly polar metabolites for metabonomic studies. 相似文献
68.
Temperature- and pH-dependent morphology and FT-IR analysis of magnesium carbonate hydrates 总被引:3,自引:0,他引:3
Zhang Z Zheng Y Ni Y Liu Z Chen J Liang X 《The journal of physical chemistry. B》2006,110(26):12969-12973
Various morphologies of magnesium carbonate hydrates have been synthesized by carefully adjusting the reaction temperature and pH value of the initial reaction solution in the precipitation process. At lower temperatures (from room temperature to 328 K) and lower pH values (variation with the reaction temperature), magnesium carbonate hydrates are prone to display needlelike morphology, and the axis diameter of the particles decreases with the increase of reaction temperature and pH value. With the further increase of the reaction temperature (333-368 K) and pH value, the sheetlike crystallites become the preferred morphology, and at higher temperatures and pH values, these crystallites tend to assemble into layerlike structures with diverse morphologies, such as spherical-like particles with rosette-like structure and cakelike particles built from sheetlike structure. Fourier transform infrared (FT-IR) spectra show that these various morphologies are closely related to their compositions. The needlelike magnesium carbonate hydrate has a formula of MgCO3.xH2O, in which the value x is greatly affected by the experimental conditions, whereas with the morphological transformation from needlelike to sheetlike structure, their corresponding compositions also change from MgCO3.xH2O to Mg5(CO3)4(OH)2.4H2O in the interval of 328-333 K. 相似文献
69.
Yanyan Zhao Zhimou Guo Xiuli Zhang Xinmiao Liang Yukui Zhang 《Journal of separation science》2010,33(9):1224-1230
An off‐line 2‐D RPLC/RPLC system incorporating a β‐CD based column and a BEH C18 column was developed in the separation of components in Dalbergia odorifera T. Chen. (Jiang Xiang). Both orthogonality and van Deemter curves of the two columns were investigated. The orthogonality was about 57%, which was evaluated with 40 standard solutes. Optimized column efficiency could be achieved under optimal linear velocity (0.04 cm/s) on the CD column or under high linear velocity (0.32 cm/s) on the BEH C18 column. With the 2‐D LC system, totally 637 peaks were separated in 114 fractions from the extraction of Jiang Xiang. Meanwhile, 19 flavanoids were tentatively identified from 114 fractions with Q‐TOF MS. The results demonstrated the separation power of this 2‐D LC system and further proved the high orthogonality between CD and C18 columns. 相似文献
70.
The retention factors (k) of 104 hydrophobic organic chemicals (HOCs) were measured in soil column chromatography (SCC) over columns filled with three naturally occurring reference soils and eluted with Milli-Q water. A novel method for the estimation of soil organic partition coefficient (Koc) was developed based on correlations with k in soil/water systems. Strong log Koc versus log k correlations (r>0.96) were found. The estimated Koc values were in accordance with the literature values with a maximum deviation of less than 0.4 log units. All estimated Koc values from three soils were consistent with each other. The SCC approach is promising for fast screening of a large number of chemicals in their environmental applications. 相似文献