共查询到20条相似文献,搜索用时 875 毫秒
1.
2.
3.
4.
在流动相组成为正己烷/异丙醇(80/20, 0.1%三氟乙酸,V/V),温度291~313K条件下,考察了4种外消旋硒(硫)代缩水甘油醚手性拆分的热力学行为.计算了对映体与固定相相互作用的焓变以及焓变差值和熵变差值等热力学参数.手性色谱柱填料为自制的纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相.实验结果表明,在考察的温度范围内,随温度升高,样品的保留、分离因子均减小,分离度呈不同的变化,4种手性样品对映体的拆分过程都是焓控过程. 相似文献
5.
以组氨酸-β-环糊精(β-CD-E_2)衍生物作为手性选择剂,利用原位聚合反应制得新型β-CD衍生物手性高效毛细管电泳(HPCE)整体柱,将其应用于手性药物羟丙哌嗪的消旋体拆分。分别探究了不同缓冲体系的洗脱能力、缓冲液pH对分离的影响以及羟丙哌嗪手性拆分的线性范围。结果表明,在最佳条件下,羟丙哌嗪对映体在β-CD-E_2整体柱上能得到较好拆分,分离度Rs达到40.52,且羟丙哌嗪浓度在9.8×10~(-6)~2.0×10~(-5)mol/L范围内与对映体峰高、峰面积具有一定的线性关系。此工作将β-CD-E_2作为HPCE固定相,为手性药物羟丙哌嗪建立了一种新的分离分析体系。 相似文献
6.
7.
手性对映体的拆分是当前备受关注的一个研究领域。手性对映体的拆分方法有多种, 手性液-液萃取拆分法是其中有较好发展前景的一种手性对映体拆分技术。本文概述了手性液-液萃取技术的基本原理, 并进一步对酒石酸类手性萃取剂、环糊精类手性萃取剂、冠醚类手性萃取剂、金属络合物类手性萃取剂等不同种类手性萃取剂及其研究进展进行了综述。分析表明, 手性液-液萃取拆分技术对外消旋体特别是药物外消旋体的拆分有较好的效果, 随着对手性萃取剂研究的进一步深入, 手性液-液萃取有望成为一种手性化合物拆分的重要方式。 相似文献
8.
9.
10.
高效液相色谱纤维素类手性固定相对外消旋稻丰散的拆分 总被引:4,自引:0,他引:4
合成了纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相,制备了手性色谱柱,以正己烷为流动相,添加异丙醇为改性剂,在高效液相色谱上实现了对手性农药稻丰散光学异构体的直接拆分;系统摸索了异丙醇含量、色潜柱长度、流速及温度对拆分效果的影响,优化了拆分条件。结果显示,色谱柱长度对该化合物的拆分影响较大;流动桕巾异丙醇含量的减少以及流速减慢均有利丁对映体的拆分,但也导致保留增强;在5℃.40℃范刚内,温度升高分离度减小。使用长色谱柱,选择适温20℃,调整流动相中正己烷与异丙醇的比例为99.5:0.5(v/v),流速为0.5ml/min时,可达到最佳分离效果,分离因子为1.38。 相似文献
11.
The use of methanol-gasoline blends as automotive fuel is limited, in part, by phase separation at low temperatures. The separation temperature of these mixtures can be adjusted by varying the percentage of blending agent present. Two blending agents were considered in this study, tertiary butyl alcohol and isopropyl alcohol. Both were found to significantly lower the separation temperature, although, isopropyl alcohol is more effective, possibly due to its greater ability to form hydrogen bonds. Correlation equations were derived relating the percentage compositions and the separation temperature. 相似文献
12.
13.
Liquid-liquid extraction of fatty acids from a vegetable oil is accomplished by aqueous isopropyl alcohol in the ratio of
1:1 in two-stage extractions at 30±2°C. The mixtures studied contained 0 to 50 fatty acids in groundnut oil, and aqueous isopropyl
alcohol solutions were of 75, 80, 85, 95 and 99% concentrations. Phase separation depends on (i) the fatty acids content in
the model mixture, and (ii) the concentration of aqueous isopropyl alcohol. Selective fatty acid separation and phase separation
could be achieved by use of aqueous (75 and 80%) isopropyl alcohol over the whole range of fatty acid content in the model
mixture. 相似文献
14.
We made poly(ether‐block‐amide) membranes by casting a solution on a nonsolvent surface. The effects of the solvent ratio (n‐butanol/isopropyl alcohol), temperature, and polymer concentration on the quality of the membranes were studied. The results show that the film quality was enhanced with increasing isopropyl alcohol ratio in the solvent. This behavior was related to the reduction of the solution surface tension and the interfacial tension between the solution and nonsolvent. Uniform films were made at a temperature range of 70–80°C and a polymer concentration of 4–7 wt %. The morphology of the membranes was investigated with scanning electron microscopy. The qualities of the films improved with increasing isopropyl alcohol ratio in the solvent. With these membranes, the pervaporation of ethyl butyrate (ETB)/water and isopropyl alcohol/water mixtures was studied, and high separation performance was achieved. For ETB/water mixtures, with increasing ETB content, both the permeation flux and separation factor increased. However, for isopropyl alcohol/water mixtures, with increasing isopropyl alcohol content, the permeation flux increased, but the separation factor was diminished. Increasing temperature in a limited range resulted in a decreasing separation factor and an increasing permeation flux. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
15.
目的:建立阿昔洛韦中的残留溶剂乙醇、异丙醇、甲苯的分离测定方法。方法:采用Agilent-DB-1石英毛细管气相色谱柱(30mX0.53nunx5.00胁m),载气为氮气,氢火焰离子化检测器,进样口温度为180℃,检测器温度为250℃。柱温采用程序升温:初始温度为40℃。维持0min,以20℃·min^-1叫速率升至80℃,维持12min;流速为5mL·min^-1。以二甲基亚砜为样品溶剂。结果:乙醇、异丙醇、甲苯的检测限分别为0.257,O.216,O.074μg·mL^-1;定量限分别为1.026,1.020,0.520μg·mL^-1;平均回收率(n=9)分别为100.2%,100.6%,101.2%。结论:本法操作简便,灵敏度高、准确性强;适用于阿昔洛韦中残留溶剂的检测。 相似文献
16.
用填充柱超临界流体色谱制备性拆分香料3-甲基-γ-辛内酯4个光学立体异构体。3-甲基-γ-辛内酯(合成的)首先在硅胶柱上制备拆分得其cis-、trans-异构体。然后,在分析模式下,考察手性柱种类、改性剂种类、改性剂含量、柱温、柱压的影响,获得拆分cis-、trans-异构体的较佳超临界流体色谱条件,cis-异构体:手性柱Chiralpak AD-H,柱温30℃,柱压9 MPa,改性剂甲醇体积分数4.0%,流动相流速1.5 mL/min,分离度1.45;trans-异构体:手性柱Chiralpak AD-H,柱温30℃,柱压10 MPa,改性剂甲醇体积分数4.5%,分离度2.24。在较佳的条件下对cis-、trans-异构体进行制备规模手性拆分得mg级4个光学立体异构体产品,光学纯度(对映体过量e.e)均为100%。 相似文献
17.
18.
19.