酰胺类手性固定相的研究进展

近年来手性拆分成为新的研究热点,手性固定相的研究发展异常迅速.立足于国内外手性固定相的研究成果,介绍了手性固定相的分类及其应用,并重点综述了基于酰胺的手性固定相的发展及其制备方法.同时简要介绍了作为手性固定相对不同异构体的识别机理,并对该领域未来的发展方向进行了展望.     

淀粉苯基氨基甲酸酯类手性固定相的制备及用于HPLC手性体分离性能的研究

合成了含有3,5-二甲基和3,5-二氯取代基团的混合型淀粉(苯基氨基甲酸酯)衍生物(CSP-2),并作为手性体分离材料涂敷在氨丙基化多孔硅胶表面,制得新型高效液相色谱(HPLC)用手性固定相;通过1H核磁共振(1H NMR)和红外光谱(IR)表征衍生物结构;以正己烷-异丙醇(9∶1,v/v)为流动相,对多种手性对映体进行了拆分;结果表明,CSP-2综合了单一取代基团淀粉(苯基氨基甲酸酯)衍生物的手性拆分性能,具有优越的手性分离能力,同时固定相的稳定性大大增强。     

HPLC用苯基氨基甲酸酯类手性固定相的制备及分离性能

合成了同时含有3,5-二甲基和3,5-二氯取代基团的纤维素(苯基氨基甲酸酯)衍生物(CSP-1),作为手性体分离材料涂敷在氨丙基化硅胶表面,制得新型高效液相色谱(HPLC)用手性固定相;利用1H核磁共振(1H-NMR)和红外光谱(IR)表征了衍生物结构;以正己烷-异丙醇(体积比9∶1)为流动相,对多种手性对映体进行了拆分。结果表明,CSP-1具有很好的手性体分离能力,综合了单一取代基团纤维素(苯基氨基甲酸酯)衍生物的手性拆分性能。     

刷型手性固定相及其在手性化合物分离中的应用

对映体的分离在有机合成、动力学、药理学、药效学及农业化学等许多学科领域内具有重要的意义,液相色谱手性固定相法拆分对映体的方法被认为最准确、方便的方法之一,刷型手性固定相是液相色谱中非常重要的一类手性固定相。本文介绍了目前常用的几种刷型手性固定相及其在手性化合物分离中的应用情况。     

高效液相色谱用键合型淀粉苯基氨基甲酸酯手性固定相的制备及拆分性能

合成了含有少量硅氧烷基团的直链淀粉(苯基氨基甲酸酯)衍生物,通过硅氧烷基团在酸性条件下的水解、缩合,可简单、高效地实现在多孔硅胶表面的化学键合,制得键合型高效液相色谱(HPLC)手性固定相;利用1H核磁共振(1H-NMR)和红外光谱(IR)表征衍生物结构;作为填充材料(CPMs)制备的高效液相色谱柱,流动相选择范围更广,可以适用各种溶剂作为流动相,通过调整含有氯仿和四氢呋喃(不能用在传统的涂覆型手性柱中)的成分和配比,对于多种手性对映体有很好的拆分能力。     

有机相模式下华法令等在氯代淀粉衍生手性固定相上的拆分

利用涂敷型直链淀粉三-(5-氯-2-甲基苯基氨基甲酸酯)手性固定相Lux Amylose-2,有机相模式下考察了其对黄烷酮、氢化安息香、安息香及华法令等的拆分。乙腈作为流动相的主体,探讨了流动相中甲醇含量、醋酸添加剂、柱温等对手性拆分的影响。黄烷酮、氢化安息香及华法令得到了良好的分离,分离度分别可达11.39、12.15及6.33。在0.005 mg/mL-4.0 mg/mL区间,华法令峰面积与浓度之间呈良好的线性关系,检测限可达0.0001 mg/mL,可用于华法令异构体含量的分析。     

配体交换色谱手性固定相法拆分与定量茶氨酸对映体

本文建立了配体交换色谱手性固定相法拆分与定量茶氨酸对映体的方法。色谱条件为:L-羟基脯氨酸键合手性柱;0.8mmol/L的硫酸铜-水溶液为流动相;波长254nm;流速1.0mL/min;柱温30℃。L-茶氨酸的进样量在0.08126～4.5144μg范围内峰面积与进样量之间呈现良好线性关系,加标回收率为97.26%～102.1%,检测限为0.02742μg,定量限为0.06503μg;D-茶氨酸的进样量在0.08250～4.5832μg范围内峰面积与进样量之间线性关系良好,加标回收率在97.07%～101.2%,检测限为0.02941μg,定量限为0.06982μg。该方法具有良好的稳定性和准确度。     

色氨酸在自制人血清白蛋白手性柱上的拆分及手性识别机理研究

人血清白蛋白与三氯聚氰活化的氨丙基硅胶反应,制得人血清白蛋白键合手性固定相。反相模式下,色氨酸在该手性固定相上获得理想的拆分,分离因子可达3.51,分离度达5.49。探讨了流动相p H值、有机修饰剂、柱温等对手性拆分的影响。通过前沿分析法对色谱保留机理进行了探讨。     

色氨酸在自制牛血清白蛋白手性柱上的拆分

利用三氯聚氰活化的氨丙基硅胶与牛血清白蛋白反应,快速而经济地制得牛血清白蛋白手性固定相。在反相模式下,将该手性固定相用于色氨酸的拆分,系统探讨了流动相pH值、柱温、有机修饰剂的种类及含量等对手性拆分的影响。色氨酸在自制牛血清白蛋白手性柱上得到了理想的拆分,分离因子可达4.33。     

手性固定相用纤维素苯甲酸酯的合成

研究了微晶纤维素和苯甲酰氯在多相条件下合成制备纤维素苯甲酸酯(CB)的反应,通过元素分析所得碳的质量百分含量计算了产物的取代度(D S),并系统研究了吡啶与N,N-二甲基乙酰胺或与三乙胺混合反应溶剂、苯甲酰氯与纤维素羟基的摩尔比r、反应温度和反应时间对D S的影响,用FT-IR和1H-NM R对产物进行了表征。实验结果表明,反应溶剂、r、反应温度和反应时间对D S影响显著;当r为2.6时,在含吡啶约50%(体积分数)的N,N-二甲基乙酰胺溶液中,于95℃反应3h获得了最高取代度的CB(D S=2.91)。     

Enantiomer separation by countercurrent chromatography using cinchona alkaloid derivatives as chiral selectors

Cinchona-derived anion-exchange-type chiral selectors have been adapted and employed in countercurrent chromatography (CCC) for the separation of enantiomers of N-derivatized amino acids and 2-aryloxypropionic acids. The accurate optimization of the enantioseparation in terms of solvent system composition, pH values, ionic strength, and CCC operating conditions was performed. A wide range of solvent mixtures was evaluated. Successful resolutions were achieved in systems such as ammonium acetate buffer/tert-amyl alcohol/methanol/heptane and especially ammonium acetate buffer/methyl isobutyl ketone or diisopropyl ether. Up to 300 mg (0.92 mmol) of N-(3,5-dinitrobenzoyl)-(+/-)-leucine was totally resolved in a single run using a 10 mM concentration of chiral selector in 122 mL of stationary phase. This amount could be increased up to 900 mg (2.77 mmol) when pH-zone-refining mode was applied. The results here presented account for the high potential of CCC as a preparative enantiomer separation technique.     

密差分相式液膜法提取L-苯丙氨酸

采用密差分相液膜分离技术，以P204为载体，H2SO4为反萃剂，以初始浓度15．28g/L的L－苯丙氨酸水溶液提取5次后，浓度降至1．92g/L，反萃相中L－苯丙氨酸浓度达54．35g/L，膜溶胀和破裂均较小，过程不需要制乳和破乳；对反萃剂也进行了后处理。     

Evaluation of a vancomycin chiral stationary phase in capillary electrochromatography using polar organic and reversed-phase modes

A vancomycin chiral stationary phase (CSP) was fully evaluated in capillary electrochromatography (CEC) in reversed-phase and polar organic modes for a number of racemic pharmaceutical compounds. High efficiency and resolution values were obtained for a number of compound classes including thalidomide in both the polar organic mode (190000 plates meter(-1) and Rs = 13.8) and reversed-phase mode (125000 plates meter(-1) and Rs = 13.0). Experimental parameters, including organic modifier, organic solvent ratio, ionic strength, pH, temperature, and voltage, were examined in both the aqueous and nonaqueous modes to deduce their effect on the resultant EOF, retention times, resolution, and efficiency of chiral separations. All results were consistent with and found to be a combination of what is known from existing literature on CEC theory and experience obtained with macrocyclic antibiotic CSPs in LC. Column stability was excellent, and each column packed was found to offer repeatable separations even when switching from the aqueous to the nonaqueous mode.     

Ion chromatographic separation of rare-Earth elements using a nitrilotriacetate-type chelating resin as the stationary phase

The chromatographic retention behavior of rare-earth elements (REEs) on a chelating resin having a nitrilotriacetate group (NTA gel) was evaluated. The capacity factors for a series of REEs on the NTA gel were in fairly good agreement (R(2) = 0.978) with the stability constants of the corresponding NTA complexes. The NTA gel was applied to the column stationary phase for the ion chromatographic separation of REE. A favorable separation of a series of REEs was achieved within 15 min using a gradient elution of nitric acid. The separated REE ions were detected using the postcolumn derivatization method with chlorophosphonazo III as a colorization reagent. The present chromatographic system, interfaced with inductively coupled plasma mass spectrometry, was applied for the simultaneous determination of 14 REEs.     

Multilevel image authentication using shared secret threshold and phase retrieval

A new kind of multilevel authentication system based on the (t, n) threshold secret sharing scheme and the iterative phase retrieval algorithm in Fresnel domain is proposed, in which, the first phase distribution iteratively generated is divided into n parts and delivered to n different participants, during high-level authentication, any t (t?≤?n) or more of them can be collected to reconstruct the original meaningful certification image; While in the case of low-level authentication, any t???1 or fewer will gain no significant information of certification image, however, it can result in a remarkable peak output in the nonlinear correlation coefficient of the recovered image and the standard certification image, which can successfully provide an additional authentication layer for the high-level authentication. Theoretical analysis and numerical simulations both validate the feasibility of our proposed scheme.     

前沿分析法测定色氨酸在牛血清白蛋白手性柱上的吸附等温线

利用三氯聚氰活化的氨丙基硅胶与牛血清白蛋白反应,快速而经济地制得牛血清白蛋白手性固定相。运用前沿分析法,反相模式下获得色氨酸对映体在牛血清白蛋白手性固定相上的平衡吸附量,并将实验数据与Langmuir、bi-Langmuir、Toth和Langmuir-Freundlich四种等温吸附模型进行了拟合,结果显示吸附数据与bi-Langmuir模型最为吻合,进一步说明了该手性固定相对色氨酸存在手性识别和非手性识别两种不同类型的吸附位点。     

Stability of He II phase separation - investigations with the active phase separator

External influences or internal disturbances may result in phase separation instabilities which could lead to operational failure of He II space cooling systems. Possible instabilities are defined and, using the active phase separator, suitable measures for prevention and control are discussed. Experimental results with a superleak arranged in parallel to the active phase separator indicate an additional possibility for adaptation of the latter to specific demands.