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排序方式: 共有361条查询结果,搜索用时 15 毫秒
111.
Bezhan Chankvetadze 《Journal of separation science》2010,33(3):305-314
This short overview summarizes the development in the field of enantioselective monolithic chromatographic media and their application for pressure‐driven and electrokinetic separations. The major emphasis is put on the currently existing problems and the author's vision for their solution is provided. Due to the author's personal experience silica‐based monoliths are discussed in more detail although the key developments in the field of organic monolithic materials for separation of enantiomers are also discussed. 相似文献
112.
Toshimasa Katagiri Satoshi Takahashi Miki Suzaki 《Journal of fluorine chemistry》2010,131(4):517-6344
The paper provides evidence for the existence of a multi-center hydrogen bonding network of trifluorolactate, the structure of which was elucidated by single crystal X-ray diffraction analysis, in the liquid state. We reported that the trifluorolactate experienced discrimination of its enantiomeric excess by distillation. X-ray crystallographic analyses of the single crystals of the trifluorolactates suggested that the phenomenon could be caused by a homo-chiral recognizing hydrogen bonding system. Low-angle X-ray diffraction measurement of the trifluorolactate in the liquid state showed a ca. 5 Å repeated, which indicates the existence of the hydrogen bonding network in the liquid state. Here, the chiral recognition could be caused by the electrostatic repulsion of the negative charges on trifluoromethyl groups. 相似文献
113.
114.
Summary A computer-assisted method is described for optimization of multi-component, mobile phase selection for separating enantiomers of four pesticides in normal-phase HPLC. The method is based on the triangle, solvent-selection concept using a statistical scanning method. The optimization of the separation over the experimental region is based on a special polynomial estimation from seven experimental runs, and resolution (Rs) is used as the selection criterion. Excellent agreement was obtained between predicted and experimental data. 相似文献
115.
Summary Direct chiral-phase HPLC methods have been developed for the determination of flurbiprofen and its major metabolites, namely
4′-hydroxyflurbiprofen and 3′-hydroxy-4′-methoxyflurbiprofen, in biological fluids using a derivatized amylose chiral stationary
phase (CSP; Chiral-pak AD). Quantification of all three analytes, both free and conjugated, in urine was carried out following
liquid-liquid extraction using tandem ultraviolet (UV) and fluorescence detection. Determination of flurbiprofen and the 4′-hydroxy-metabolite
in plasma utilized the same CSP but required modification in the mobile phase composition and sole use of fluorescence detection.
The urine assay was linear (r>0.998) between 0.05–10 μg mL−1, 0.1–20 μg mL−1 and 0.01–2 μg mL−1 for the enantiomers of flurbiprofen, 4′-hydroxyflurbiprofen and 3′-hydroxy-4′-methoxyflurbiprofen respectively. The plasma
assay was linear (r>0.997) between 0.1–6 μg mL−1 and 0.01–0.6 μg mL−1 for the enantiomers of flurbiprofen and 4′-hydroxyflurbiprofen respectively. Both assays, typically yielded within- and between-day
imprecision and accuracy values less than 10% for the enantiomers of the different analytes. Initial volunteer studies suggest
that the disposition of flurbiprofen displays modest enantioselectivity in humans. 相似文献
116.
Summary The chromatographic characteristics of the thiazolidine carboxylic acids formed by the reaction of D- and L-penicillamine
with various substituted benzaldehydes and heterocyclic aldehydes have been studied on Chiralplate layers. It has been found
that the nature and position of substituents strongly affect the RF values and resolution factors (RS) of the isomers. An unambiguous relationship has been established between the RS values of the L- and D-enantiomers and the dipole moment of the aldehydes. The transformation to thiazolidine carboxylic
acids with benzaldehyde and substituted benzaldehydes, however, is not complete, thus the reaction with formaldehyde is still
more suitable for quantitative determination of penicillamine isomers. 相似文献
117.
Philip J. Cox Susan Blaney Steve W. Love Norman Shankland David B. Sheen 《Journal of chemical crystallography》1995,25(12):845-850
The solid solution formed by the title compound, C9H16NO3, has been examined by a variety of techniques and shown to be an equi-molecular mixture of the two enantiomers. Refinement of the disordered structure was based on the orthorhombic space groupPnma witha=8.023(2),b=10.030(3), andc=12.352(2)Å, finalR=0.055. The oxygens of the carboxyl group are disordered and both enantiomers can occupy the same, rather than alternate, crystallographic sites. Results from studies involving IR, GC-MS, and chiral chromatography are also presented. In addition we report on the use of synchrotron X-ray topography to investigate strain in crystals of the solid solution. 相似文献
118.
119.
120.
手性配位体交换流动相添加剂法拆分对映体 总被引:7,自引:0,他引:7
综述了手性配合基交换色谱法通常采用三种手性相系统中的流动相添加剂方法。主要内容有:(A)手性配合基交换机制,给出了描述对映体对在色谱系统中的保留时间和分离选择性的公式,包括手性选择剂在固定相和流动相中的各种不同情况。公式表明整个色谱往系统的对映体选择性不同于溶液中所存在的选择剂与被选择物作用的情况;(B)影响配合交换的参数,讨论了金属离子、金属离子/配位体比率、金属离子络合物浓度、固定相、流动相pH、洗脱顺序、有机调节剂、离子对试剂、流动相离子强度、温度、立体选择性和手性交互识别;(C)应用。 相似文献