精喹禾灵及其S-对映体的手性分离与紫外光谱研究

采用高效液相色谱法完成了精喹禾灵及其S-对映体在NucleosilChiral-2上的手性分离,以正己烷作流动相,选择添加适量异丙醇和微量三氟醋酸作为改性剂,达到了满意的手性分离效果。通过一阶导数光谱和二阶导数光谱,进行R-对映体和S-对映体紫外光谱的比较研究,验证了两个光学异构体在设定试验条件下具有完全一致的紫外光谱特征。     

3-甲基-γ-辛内酯超临界流体色谱立体异构性制备拆分

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%。     

3-甲基-γ-辛内酯的超临界流体色谱立体异构性制备拆分

用填充柱超临界流体色谱制备性拆分香料3-甲基-γ-辛内酯四个光学立体异构体。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,改性剂甲醇含量4.0 % (v/v),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,改性剂甲醇含量4.5 % (v/v),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级四个光学立体异构体产品,光学纯度(对映体过量, e.e %)均为100%。     

反相高效液相色谱手性固定相法分离喹禾灵光学异构体

对除草剂喹禾灵光学异构体进行有效的分离.以Chiralcel AD-RH手性柱的R-HPLC,分别考察了流动相乙腈-水的比例、流速及柱温对喹禾灵光学异构体手性分离的影响.确定了分离喹禾灵光学异构体的最佳色谱条件:流动相为乙腈-水(体积比65∶35),流速为0.5 mL/min,柱温为25℃.在所选定的色谱条件下,喹禾灵光学异构体的分离度(R)和分离因子(α)分别为2.11和1.19.并通过分离过程中的热力学参数的计算,探Chiralcel AD-RH手性柱对喹禾灵光学异构体的手性识别机理,证实了喹禾灵光学异构体的分离是焓驱动的过程.     

多沙唑嗪中间体的手性分离方法优化研究

多沙唑嗪是一种抗高血压手性药物,1-(1,4-苯并二口恶烷-2-羰基)哌嗪(BCP)是合成该药物的重要手性中间体。手性多沙唑嗪的光学纯度可以通过BCP的光学纯度来控制。该文采用柱前衍生化-反相高效液相色谱法优化了BCP的手性分离方法,以便对其进行光学纯度检测。结果表明:以乙酰葡萄糖异硫氰酸酯(G ITC)为柱前手性衍生化试剂,C18柱(4.6 mm×250 mm)为色谱柱,可以将BCP对映体分离,优化的其他色谱条件为:流动相组成V(CH3OH)∶V〔c(KH2PO4的水溶液)=0.02 mol/L〕=50∶50,流速0.6 mL/m in,检测波长250 nm。在选择的测定条件下,BCP与G ITC形成的非对映异构体达到基线分离,分离度约等于1.5(R=1.5),在2~250μg.mL-1内,非对映体的色谱峰面积与质量浓度之间线性相关系数大于0.998。     

烟碱手性异构体的分离分析

建立了烟碱手性异构体的高效液相色谱分离分析方法。采用CHIRALPAK IG-3手性色谱柱,流动相:30%乙腈-70%20 mmol/L碳酸氢铵水溶液,可有效分离烟碱手性异构体。以天然左旋烟碱为标准品,采用外标法在260nm波长检测,结果表明:在0.0001～0.01 g/mL范围内,左旋异构体的峰面积与其质量浓度呈现良好的线性关系,决定系数(R2)为0.999,方法的检出限为9.3×10^-8g/mL,平均回收率99.4%,相对标准偏差小于0.5%(n=8),准确度和重现性较好。烟碱手性异构体的响应因子为1.01,可以采用归一化法测定左右旋异构体相对含量。     

喹禾糠酯原药的手性分离及有效体的定量分析

采用高效液相色谱法,以Chiralpak AD-H手性柱,对喹禾糠酯原药中4个手性异构体进行分离,并对其有效体(R,R)和(R,S)体进行定量分析。结果表明:该方法可以使喹禾糠酯中的4个手性异构体达到基线分离,分析方法线性相关系数为0.9999,变异系数为0.14%,回收率在98.37%~101.79%之间。     

羟丙哌嗪手性拆分的HPCE新方法

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。     

吡氟氯禾灵的高效液相色谱法拆分与测定

在流动相为正庚烷-异丙醇-三氟乙酸（体积比为99．3：0．5：0．2）,流速为0．6mL／min,检测波长为278nm,柱温为10℃的分析条件下,利用手性色谱柱Nucleosil chiral-2成功实现了吡氟氯禾灵对映体的手性分离,并建立了对有活性的尺型异构体的定量测定方法。     

纤维素-三(3,5-二甲基苯基氨基甲酸酯)对烯唑醇对映体的直接拆分

制备了纤维素-三(3，5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC)，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烯唑醇光学异构体的直接拆分，探讨了改性剂的含量及色谱柱长对拆分效果的影响，从而优化了拆分条件。试验结果显示，流动相中异丙醇含量的减少有利于对映体的拆分，但保留增强；长色谱柱也有利于对映体的分离。使用两色谱柱串连，当流动相中正己烷与异丙醇的比例为95：5时可达到最佳分离效果，分离因子为1．17。     

Quantitative analysis of brain and spinach leaf lipids employing silicic acid column chromatography and acetone for elution of glycolipids

Quantitative elution of acidic and neutral glycolipids of brain and spinach leaves from silicic acid columns with acetone was demonstrated. Cerebrosides and sulfatides of brain and sulfolipid and glycosyl diglycerides of spinach leaves were eluted quantitatively with acetone while prospholipids remained on the column. The observations provide the basis for an analytical procedure employing column and quantitative thin-layer chromatography (TLC). Sephadex column chromatography is utilized for separation of lipids from nonlipids; silicic acid column chromatography for separation into neutral lipid, glycolipid and phospholipid fractions; and quantitative TLC for analysis of lipid classes of each column fraction.     

Two procedures to remove polar contaminants from a crude brain lipid extract by using prepacked reversed-phase columns

Two procedures were developed using prepacked, reversed-phase columns (Bond Elut) for the separation of lipids from water-soluble contaminants. A crude lipid extract from brain tissue, was diluted stepwise with a methanol/water (method 1) or a methanol/saline (method 2) mixture and, with each step, was passed through the column. As the polarity of the solvent was increased, all lipids became bound to the column, while the water-soluble compounds remained in the eluate. After three subsequent dilutions and column elutions, the eluate containing the more polar contaminants was discarded. The bound lipids were then eluted with a small volume of chloroform/methanol (1∶2, v/v). Alternatively two fractions were eluted, the first fraction eluted with methanol/water (12∶1, v/v), contained gangliosides, phosphatidyl-serine, phosphatidylinositol, phosphatidic acid and sulfatides. The second fraction, eluted with chloroform/methanol (1∶2, v/v), contained all remaining phospholipids, cerebrosides and cholesterol. For both methods a quantitative recovery of cholesterol and phospholipids was obtained. In method 2, when water was replaced by saline in the dilution solvent mixture, gangliosides were also bound and quantitatively recovered.     

Rapid separation of neutral lipids,free fatty acids and polar lipids using prepacked silica sep-Pak columns

A method is described for the separation of neutral lipid, free fatty acid and polar lipid classes using small (600 mg), prepacked silica Sep-Pak columns. Combinations of hexane and methyltertiarybutylether were used to progressively elute cholesteryl ester first then triglyceride from the column. After column acidification, fatty acids were eluted followed by cholesterol. Recoveries of these lipids were 96% or greater. Polar lipids were eluted from the column using combinations of methyltertiarybutylether, methanol and ammonium acetate. Phospholipid classes could not be separated completely from each other. Phosphatidylethanolamine and phosphatidylinositol eluted together, whereas the more polar phosphatidylcholine, sphingomyelin and lysophosphatidylcholine were eluted as a second fraction. Recoveries of each phospholipid was greater than 98%.     

Analytical separation of nonlipid water soluble substances and gangliosides from other lipids by dextran gel column chromatography

A column chromatographic procedure is reported utilizing a dextran gel (Sephadex) for the complete separation of the major lipid classes from water-soluble nonlipids. Lipids other than gangliosides are eluted first with chloroform/methanol 19/1 saturated with water, gangliosides with chloroform/methanol/water containing acetic acid, and water-soluble nonlipids with methanol/water 1/1. Results for adult human whole brain, grey and white matter, and normal infant whole brain lipids are presented. With beef brain lipid as sample the ganglioside fraction is essentially pure, but with human brain lipid samples only about 70% of the second fraction is ganglioside. All ganglioside and water soluble nonlipid of a human spleen chloroform/methanol extract was separated from lipids with the procedure. Control studies with P³²O₄≡ and C₁₄ labelled glucose showed that all counts were present in fraction 3. Similar studies with C₁₄ labelled amino acids (glycine, serine, alanine, phenylalanine) showed that only phenylalanine counts were eluted in fraction 2 along with the gangliosides. The procedure was applied for removal of large amounts of ammonium acetate from DEAE cellulose column fractions and for complete removal of adsorbent and salts from lipids eluted from thin-layer chromatograms. After passage through the dextran gel columns, lipids eluted from thin-layer chromatograms were found to give infrared spectra identical to those of pure samples obtained by other procedures.     

Polymerized high internal phase emulsion monoliths for the chromatographic separation of engineered nanoparticles

PolyHIPEs of ethylene glycol dimethacrylate (EGDMA) and styrene/divinylbenzene were prepared by polymerization of water‐in‐oil high internal phase emulsions (HIPEs) within high pressure liquid chromatography (HPLC) columns. The columns were incorporated into a HPLC system affixed to an inductively‐coupled plasma mass spectrometer, and their potential for the separation of engineered nanoparticles was investigated. Triplicate injections of 5 and 10 nm gold particles injected onto a poly(styrene‐co‐divinylbenzene) polyHIPE column produced an average difference in retention time of 135 s. On a poly(EGDMA) column, triplicate injections of dysprosium containing polystyrene particles of 52 and 155 nm produced a difference in retention time of 8 s. In both cases the smaller particles eluted from the column first. Comparison, using scanning electron microscopy, of the polyHIPE columns after the separations, against freestanding monoliths produced from the same HIPEs, revealed no apparent change in the internal porous structure of the polyHIPEs. © 2015 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 132, 41229.     

Analysis of a hybrid distillation-pervaporation column in a single unit: Intermediate membrane section in the rectifying and stripping section

Distillation-pervaporation in a single unit (DPSU) column can perform separations that are not possible in conventional distillation by overcoming distillation boundaries. Unlike conventional hybrid distillation-pervaporation columns, in a DPSU system the pervaporation membrane is located inside the column. The separation by distillation and pervaporation is carried out simultaneously inside the same column section. In a previous work, a simplified model was used to design and analyze distillation-pervaporation in a single unit (DPSU) systems with a hybrid rectifying-pervaporation section, where the membrane constitutes the whole section. In this study, this simplified model is applied to DPSU columns where the membrane partially constitutes the rectifying or the stripping sections, including the model derivation of the stripping section and the operation leaves. The simplified model is applied for the separation of two mixtures with different Serafimov's topology classifications: acetone-isopropanol-water (topology type 1.0-2) and ethyl acetate-ethanol-methanol (topology type 2.0-2b). Thermodynamic limitations are identified for the separation of the ethyl acetate-ethanol-methanol mixture. Multiple operation leaves are produced depending on the liquid composition at the beginning of the membrane section, hindering the conditions that help to overcome the distillation boundary through a DPSU column. For some conditions, a section that is partially constituted by a membrane performs better than if the membrane constitutes the whole section.     

Foam fractionation of solutions containing two surfactants in stripping and reflux columns

An experimental and theoretical investigation was undertaken in order to examine the effect of concentration, foam flow rate and feed flow rate on the separation of sodium dodecylbenzene sulfonate and sodium lauryl sulphate from solutions containing the two surfactants, in stripping and reflux columns. The experimental results indicated the conditions under which a stripping foam fractionation column behaves according to the model of an infinite column. Within the present experimental range reflux columns behaved always according to the model of an infinite column. Using this model it is possible to predict relative separation of surfactants in stripping and reflux columns from experimental data obtained in simple columns. Experiments with modified total reflux columns indicate great potential for batch foam fractionation.     

Column chromatographic extraction for quickly separating the volatiles,flavonoids, and pectin from tangerine peel

Tangerine peel, a very abundant natural resource, only part of which has been used in traditional Chinese medicine and health foods but most were discarded as the waste, which should be fully utilized. Previous studies showed its functional components include volatiles, ?avonoids, phenolic acids, and pectin, all of which cannot be effectively extracted through traditional methods. A column chromatographic extraction with gradient elution was developed for one-step extraction of all bioactive substances from tangerine peel. Dried material was loaded into a column eluted with 2-fold of petroleum ether: ethanol (7:3, PE) for the volatiles fraction. Sequentially eluted with 4-fold of ethanol: water (5:5, EW) then separated into ?avonoids and polysaccharides by 80% ethanol precipitation of polysaccharides. The third eluted with 5-fold of water and then 60% ethanol precipitation of pectin. Through these procedures, volatiles, ?avonoids, and pectin in tangerine peel were simultaneously extracted at 98% extraction rates and simply separated at higher than 95% recovery rates. To further reduce solvent consumption and the volume of the final extract, cyclic column chromatographic extraction should be used. The method provides a simple and high ef?cient extraction and separation of a wide range bioactive substances.