二(2-乙基己基)磷酸与酒石酸衍生物复合萃取拆分扁桃酸外消旋体

本文研究了扁桃酸对映体在含二(2-乙基己基)磷酸(D2EHPA)与酒石酸衍生物复合手性选择剂的正辛醇-水两相体系中的萃取分配行为,考察了酒石酸衍生物的种类和初始浓度、D2EHPA的初始浓度、扁桃酸的初始浓度、萃取温度对分配系数和分离因子的影响.结果显示,复合手性选择剂能提高分配系数和分离因子,D2EHPA与D-酒石酸衍生物的复合手性选择剂与L-扁桃酸对映体比与D-扁桃酸对映体形成更稳定的非对映体复合物;且D2EHPA与二对甲基苯甲酰酒石酸(DTTA)的复合手性选择剂的手性选择性大于D2EHPA与二苯甲酰酒石酸(DBTA)的复合手性选择剂;同时,扁桃酸的初始浓度、萃取温度对分配系数和分离因子的影响较大.     

疏水性L-酒石酸异丁酯立体选择性萃取拆分氰戊菊酸对映体

合成了萃取拆分氰戊菊酸(FA)对映体的手性选择体L-酒石酸异丁酯.研究了氰戊菊酸对映体在含有手性选择体L-酒石酸异丁酯的水-有机相双相体系中的萃取分配行为.考察了有机稀释剂类型、L-酒石酸异丁酯浓度、pH值和磷酸盐浓度诸因素对分配系数(K)和分离因子(α)的影响.研究结果表明:L-酒石酸异丁酯与S对映体形成的复合物稳定性比与R对映体形成的复合物要好;1,2-二氯乙烷作为有机稀释剂更有利于萃取分离;随着L-酒石酸异丁酯浓度的增大,K逐渐增大,α先增大后减小,当L-酒石酸异丁酯浓度为0.30 mol\5L-1时,α达最大;pH值增大,K和α都降低;磷酸盐浓度对分配系数和分离因子也有较大影响.     

酮洛芬对映体的双相识别手性萃取分离

研究了酮洛芬在溶有酒石酸酯的有机相和β-环糊精衍生物水相萃取体系中的分配行为;考察了有机溶剂、酒石酸酯、环糊精衍生物的种类、萃取剂浓度和pH等因素对分离效果的影响。结果表明,β-环糊精衍生物优先识别S-对映体而不是R-对映体,但L-酒石酸酯的识别能力刚好相反;1,2-二氯乙烷作为有机溶剂,三甲基-β-环糊精和L-酒石酸异丁酯做手性萃取剂是最好的选择;萃取剂的浓度和pH对分离效果有明显影响;当三甲基-β-环糊精和L-酒石酸异丁酯的浓度分别为0.1mol/L和0.2mol/L、水相pH=2.5时,分离效果最好。     

疏水性L-酒石酸酯立体选择性萃取分离氯噻酮对映体

研究了氯噻酮对映体在含有疏水性L-酒石酸酯手性选择体的水-1,2-二氯乙烷两相系统萃取分配行为,考察了pH、L-酒石酸酯烷基链长度、L-酒石酸酯浓度和磷酸盐浓度对分配系数和分离因子的影响。实验表明：L-酒石酸酯与氯噻酮I( )-对映体比与Ⅱ(-)-对映体形成更稳定的非对映体复合物;随着L-酒石酸酯取代烷基链长的增长,分配系数和分离因子增大;随着pH增大,分配系数增大,而分离因子降低;同时,L-酒石酸酯和磷酸盐浓度影响也比较大。     

疏水性L-酒石酸酯萃取分离特非那丁对映体

研究了特非那丁对映体在含有疏水性L-酒石酸酯的1,2二氯乙烷溶液及甲醇水溶液两相中的萃取分配行为,考察了不同烷基链长的L-酒石酸酯,L-酒石酸酯的浓度,有机溶剂的种类,及其溶解特非那丁的甲醇水溶液浓度对分配系数K和分离因子α的影响。实验表明:L-酒石酸酯与特非那丁Ⅱ对映体形成的复合物稳定性比与特非那丁Ⅰ对映体形成的复合物稳定性要大,三类有机溶剂的萃取性能为醇>1,2二氯乙烷>烷烃;甲醇的浓度在50%~90%时,随着溶解特非那丁的甲醇水溶液中的甲醇浓度的增加,分配系数和分离因子均降低;当甲醇的浓度为50%时,可以得到最佳的K和α;随着L-酒石酸酯的浓度的提高,分配系数K和α分离因子先增加然后减小;当L-酒石酸酯的浓度约为0.25 mol/L时,K和α达到最大值;L-酒石酸酯的碳链长度对分配系数K和分离因子α也有很大的影响。     

组合手性萃取拆分克伦特罗外消旋体

以D-二苯甲酰酒石酸(D-DBTA)和D-二对甲苯甲酰酒石酸(D-DTTA)的组合作为手性选择剂,研究克伦特罗对映体在水相和有机相中的萃取分配行为,优化了手性萃取条件,考察了组合手性选择剂的不同摩尔浓度比、有机溶剂、水相pH值和亲脂性阴离子BPh4-对手性萃取性能的影响,并测定了手性萃取拆分过程中的热力学函数.在优化的手性萃取条件下,有机相中的对映体过量值(e.e.%)可大于10%,而所使用的选择剂量相对大为降低.热力学数据分析表明,该手性萃取过程为焓控过程.     

支载液膜双有机相萃取分离氧氟沙星外消旋体

基于化学热力学原理, 采用逆流分级萃取和中空纤维支载液膜技术研究了氧氟沙星外消旋体在手性环境中的萃取分离. 膜内外两相辛醇溶液中分别含有L-二苯甲酰酒石酸和D-二苯甲酰酒石酸手性选择体, 其中膜内相辛醇溶液中含有氧氟沙星外消旋体. 中空纤维膜用含有溴化十六烷基三甲胺的磷酸氢二钠/磷酸缓冲液(pH = 6.86)浸泡48 h. 改性的液膜允许氧氟沙星对映体穿过, 而手性选择体和有机溶剂不能穿过. 对中空纤维膜分级手性萃取理论, 传质性能及立体选择性进行了研究; 并建立了氧氟沙星外消旋体在中空纤维支载液膜手性分离的数学模型R/S=0.976 e^0.03NTU. 使用11个22 cm长膜器串联(传质单元数为78)逆流分级萃取, 产品光学纯度达90%以上.     

基于手性配体交换反应立体选择性萃取分离氧氟沙星对映体

基于配体交换反应,研究了氧氟沙星对映体在含有Cu²⁺和N-n-十二烷基-L-脯氨酸手性配体(L)两相体系中的分配平衡.在不同pH条件下,考察了Cu²⁺在含有N-n-十二烷基-L-脯氨酸两相中的分布;研究了pH,Cu²⁺浓度,手性配体浓度等因素对氧氟沙星对映体在两相中的分配系数(K)和分离因子(α)的影响.实验结果表明,N-n-十二烷基-L-脯氨酸对R-氧氟沙星对映体萃取能力大于对S-对映体的萃取能力;pH对K和α的影响很大,在pH值小于3.5时,L₂Cu二元配合物的生成在热力学上看是不适宜的,萃取时pH宜大于3.5;手性配体和Cu²⁺摩尔比为2:1,K和α最佳;使用2×1中空纤维膜对氧氟沙星对映体进行萃取分离,出口水相氧氟沙星对映体浓度比值(S/R)约为1.72.     

手性溶剂萃取分离顺式二氯菊酸对映体

研究了顺式二氯菊酸(cis-PA)对映体在含有酒石酸酯手性选择体的水-1-2-二氯乙烷两相溶液中的萃取分配行为,考察了有机相种类、L-酒石酸酯浓度、水相pH、L-酒石酸酯烷基链长度和萃取温度等因素对萃取分离效果的影响.结果表明,L-酒石酸酯与II对映体形成的复合物稳定性比与I对映体形成的复合物要好;1.2-二氯乙烷作为有机相效果较好;随着L-酒石酸酯浓度的增大,分配系数K逐渐增大,而分离因子α先增大然后开始减小;随着pH的增大,K和α都降低;L-酒石酸酯烷基链长度及萃取温度对K和α有较大影响.     

双相(O/W)识别手性萃取分离α-环己基扁桃酸对映体

提出一种新的手性分离技术双相(O/W)识别手性萃取. 研究了α-环己基扁桃酸对映体在D(L)-酒石酸异丁酯1,2-二氯乙烷有机相和β-环糊精衍生物水相萃取体系中的分配行为; 考察了β-环糊精衍生物种类和浓度、酒石酸酯构型和浓度、水相pH 值等因素对萃取性能的影响. 实验结果表明, 双相(O/W)识别手性萃取具有很强的手性分离能力, 羟丙基β-环糊精、羟乙基β-环糊精、甲基β-环糊精均对S-α-环己基扁桃酸对映体的识别能力大于对R-α-环己基扁桃酸对映体的识别能力, 其中以羟丙基β-环糊精的识别能力最强; 而D-酒石酸异丁酯的识别能力刚好相反; 在羟丙基β-环糊精和D-酒石酸异丁酯萃取体系中, α-环己基扁桃酸外消旋体一次萃取分离后, 水相中S-对映体e.e.%达到27.6%, R-和S-对映体的分配系数(k_R和k_S)分别为2.44和0.98, 分离因子(α)达2.49; 同时pH值和萃取剂浓度对手性分离能力有显著影响. 双相(O/W)识别手性萃取对外消旋体化合物的制备性分离有着十分重要的意义.     

气体分离膜研究进展

全面综述了近几年气体分离膜研究的最新进展,主要包括气体分离膜材料、制膜方法、表征方法三个方面。     

毛细管电泳法在手性分离中的应用及进展

近年来,毛细管电泳(CE) 手性分离方法的研究主要集中在各种手性添加剂与对映体药物的匹配及实验条件的最优化选择上.目前,较为成熟的CE分离模式有:区带电泳(CZE)、凝胶电泳(CGE)、等速电泳(CITP)、胶束电动色谱(MEKC)和非水电泳(NACE)等,并已成功地用于手性化合物对映体的分离.CE手性分离研究正朝着新型手性选择剂的研制和实现与其他各种定性分析仪器及其他色谱分离模式的联用方向发展.     

Lipophilic ternary complexes in liquid–liquid extraction of trivalent lanthanides

The formation of ternary complexes between lanthanide ions [Nd(III) or Eu(III)], octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO), and bis-(2-ethylhexyl)phosphoric acid (HDEHP) was probed by liquid–liquid extraction and spectroscopic techniques. Equilibrium modeling of data for the extraction of Nd(III) or Eu(III) from lactic acid media into n-dodecane solutions of CMPO and HDEHP indicates the predominant extracted species are of the type [Ln(AHA)₂(A)] and [Ln(CMPO)(AHA)₂(A)], where Ln?=?Nd or Eu and A represents the DEHP^? anion. FTIR (for both Eu and Nd) and visible spectrophotometry (in the case of Nd) indicate the formation of the [Ln(CMPO)(A)₃] complexes when CMPO is added to n-dodecane solutions of the LnA₃ compounds. Both techniques indicate a stronger propensity of CMPO to complex Nd(III) versus Eu(III).     

Applications of magnetic materials separation in biological nanomedicine

As a result of their advantages for superparamagnetic properties, good biocompatibility, and high binding capacity, functionalized magnetic materials became widely popular over the past couple of decades, being applied on large scale in various processes of sample preparation for biomedicine. In this work, we perform an in‐depth review on the current progress in the field of magnetic bead separation, discussing in detail the physical basis of this process, various synthesis methods and surface modification strategies. We place special focus of attention as well on the latest applications of magnetic polymer microspheres in cell separation, protein purification, immobilized enzyme, nucleic acid separation, and extraction of bioactive compounds with low molecular weight. Existing problems are highlighted and possible trends of magnetic separation techniques for biomedicine in the future are proposed.     

Fabrication of Matrimid/polyethersulfone dual-layer hollow fiber membranes for gas separation

We have developed almost defect-free Matrimid/polyethersulfone (PES) dual-layer hollow fibers with an ultra-thin outer layer of about 10 × 10⁻⁶ m (10 μm), studied the effects of spinneret and coagulant temperatures and dope flow rates on membrane morphology and separation performance, and highlighted the process similarities and differences between single-layer and dual-layer hollow fiber fabrications. The compositions of the outer and inner layer dopes were 26.2/58.8/15.0 (in wt.%) Matrimid/NMP/methanol and 36/51.2/12.8 (in wt.%) PES/NMP/ethanol, respectively. It is found that 25 °C for both spinneret and coagulant is a better condition, and the fibers thus spun exhibit an O₂/N₂ selectivity of 6.26 which is within the 87% of the intrinsic value and a calculated apparent dense-layer thickness of about 2886 × 10⁻¹⁰ m (2886 Å). These dual-layer membranes also have impressive CO₂/CH₄ selectivity of around 40 in mixed gas tests. The scanning electron microscopy (SEM) studies show that low coagulant temperatures produce dual-layer hollow fibers with an overall thicker thickness and tighter interfacial structure which may result in a higher substructure resistance and decrease the permeance and selectivity simultaneously. The elemental analysis of the interface skins confirms that a faster inter-layer diffusion occurs when the fibers are spun at higher spinneret temperatures. Experimental results also reveal that the separation performance of dual-layer hollow fiber membranes is extremely sensitive to the outer layer dope flow rate, and the inner layer dope flow rate also has some influence. SEM pictures indicate that the macrovoid formation in dual-layer asymmetric hollow fiber membranes is quite similar to that in single-layer ones. It appears that macrovoids observed in this study likely start from local stress imbalance and weak points.     

Sulfonated polysulfone-preparative routes and applications in membranes used for pressure driven techniques

There is much enthusiasm now-a-days for efforts to improve membrane performances. Membrane modification is one of the critical approaches needed for the development of membrane science and technology. The beauty of research in this orientation is that it is a dynamic process that moves forward slowly and recommendations are made based on the science available. In this regard sulfonation of polysulfones is an excellent move. The present review demonstrates different sulfonation strategies of polysulfones as well as promoting applications in pressure driven separation sciences (viz. salt, macromolecule, organic separation from water). It shows that marked path is promising one.     

Modelling of multifrequency IRMPD for laser isotope separation

The process of infrared multiple photon dissociation (IRMPD) of molecules is of great fundamental importance and has practical significance, such as isotope separation etc. Unfortunately, a clear insight into the process has been hindered by the bewildering array of important variables affecting MPD. The dissociation probability γ (φ) i.e. the yield has been found to be a sensitive function of laser fluence φ along with numerous other parameters like laser frequency, gas pressure etc. We have shown that in single frequency IRMPD, an accurate quantitative characterization of the dissociation probability can be adequately expressed by a ‘power law’ model with two fitting parameters namely critical fluence, φ_c and multiphoton order,m. This model was exploited in analysing our MPD results on various systems. However, the small isotope shift encountered in heavy elements and the sticking phenomenon observed in small light molecules restrict respectively the separation factor and the dissociation yield. These problems can effectively be tackled by irradiation with multifrequency laser beams which can be chosen appropriately on the basis of spectroscopic features. Based on our success in single frequency model, multifrequency IRMPD is modelled by a functional form containing the product of power law terms for individual fluences on irradiation frequencies. This model is successfully benchmarked with our experimental results on multifrequency LIS of tritium. Such knowledge can be utilized for appropriate separation process design, evaluation and optimization.     

Sheath-assisted versus sheathless dielectrophoretic particle separation

Lab-on-chip devices are widely being used for binary and ternary cell/particle separation applications. Among the lab-on-chip methods, dielectrophoresis (DEP) is a cost-effective and label-free method, with great capabilities for size-based separation of cells and particles, which is mostly performed in sheath-assisted forms. However, the elimination of the sheath flows offers advantages such as ease of operation and higher sample throughput. In this work, we present a comparison of sheath-assisted and sheathless DEP separation of three sizes of microparticles using tilted electrodes. The sheath-assisted design was capable of separating the 5, 10, and 15 μm particles with a separation efficiency as high as 98.0% for 15 μm particles. By adding a DEP focusing region, a sheathless DEP separator was proposed, which offered higher throughputs (up to 10 times) at the cost of lowering the separation efficiency (a reduction up to 10.3% for 15 μm) compared to the sheath-assisted design. To enhance the separation efficiency, a combination of the DEP focusing accompanied by weak sheath flows from both sides was proposed. This design achieved the highest sample separation yield in the outlets (as high as 98.7% for 15 μm) with a sample throughput of more than 4.2 μL/min. This study provides insights into the choice of an appropriate platform for any application in which the yield, purity, throughput, and portability must be considered.     

The upper bound revisited

The empirical upper bound relationship for membrane separation of gases initially published in 1991 has been reviewed with the myriad of data now presently available. The upper bound correlation follows the relationship , where P_i is the permeability of the fast gas, α_ij (P_i/P_j) is the separation factor, k is referred to as the “front factor” and n is the slope of the log–log plot of the noted relationship. Below this line on a plot of log α_ij versus log P_i, virtually all the experimental data points exist. In spite of the intense investigation resulting in a much larger dataset than the original correlation, the upper bound position has had only minor shifts in position for many gas pairs. Where more significant shifts are observed, they are almost exclusively due to data now in the literature on a series of perfluorinated polymers and involve many of the gas pairs comprising He. The shift observed is primarily due to a change in the front factor, k, whereas the slope of the resultant upper bound relationship remains similar to the prior data correlations. This indicates a different solubility selectivity relationship for perfluorinated polymers compared to hydrocarbon/aromatic polymers as has been noted in the literature. Two additional upper bound relationships are included in this analysis; CO₂/N₂ and N₂/CH₄. In addition to the perfluorinated polymers resulting in significant upper bound shifts, minor shifts were observed primarily due to polymers exhibiting rigid, glassy structures including ladder-type polymers. The upper bound correlation can be used to qualitatively determine where the permeability process changes from solution-diffusion to Knudsen diffusion.     

高效液相色谱-串联质谱法结合多糖衍生物手性固定相拆分氰戊菊酯

建立了以多糖衍生物为手性固定相的高效液相色谱-串联质谱(HPLC-MS/MS)直接拆分氰戊菊酯对映体的方法。在反相液相色谱条件下,考察了手性固定相的种类、流动相组成、柱温、流速对氰戊菊酯4个立体异构体分离的影响。同时,利用热力学方法对氰戊菊酯的立体异构体与固定相之间的色谱保留和分离的热力学机理进行了探讨。结果表明:采用Lux Cellulose-3(纤维素-三(4-甲基苯甲酸酯))手性色谱柱,在以流动相为乙腈-水(5 mmol/L甲酸铵)=(55:45,V:V)流速0.4 mL/min,柱温30℃的条件下,可在14 mins内实现氰戊菊酯4个立体异构体的基线分离。拓展了HPLC-MS/MS在菊酯类手性农药对映体分离及检测上的应用。