单分散树脂键合手性配体交换色谱固定相拆分DL-氨基酸

以单分散交联聚甲基丙烯酸环氧丙酯-甲基丙烯酸乙二醇双酯(PGMA/EDMA)树脂为基质合成了L-脯氨酸键合手性配体交换固定相,并用于DL-氨基酸的直接光学拆分,考察了流动相pH值、金属离子浓度、流速及温度等因素对DL-氨基酸对映体拆分的影响。结果表明,该固定相在配体交换色谱模式下可对多对DL-氨基酸进行良好的拆分。     

原子转移自由基聚合技术制备新型手性配体交换色谱固定相及对手性化合物的拆分

采用原子转移自由基聚合(ATRP)技术, 以溴代硅胶为引发剂, CuCl/2,2'-联吡啶(Bpy)为催化体系, 水为溶剂, N-丙烯酰基-L-脯氨酸为单体, 室温下在硅胶表面进行聚合反应, 制得硅胶接枝聚N-丙烯酰基-L-脯氨酸分子刷. 通过改变ATRP反应体系中单体的量, 制备了3种不同键合量且键合量可控的手性配体交换色谱固定相, 利用元素分析和热重分析对其进行表征. 考察了配体接枝率、 流动相Cu²⁺浓度、 pH值和柱温等对DL-氨基酸和α-羟基酸拆分的影响, 优化了色谱分离条件, 探讨了拆分过程的热力学. 结果表明, 所合成的手性配体交换色谱固定相能够分离9种DL-氨基酸和α-羟基酸, 其中DL-酪氨酸、 DL-色氨酸和DL-苏氨酸3种氨基酸可同时进行拆分, 且拆分过程由熵控制.     

新型L-羟脯氨酸聚合物键合手性固定相的制备及对手性化合物的拆分

以单分散亲水性交联聚甲基丙烯酸环氧丙酯-甲基丙烯酸乙二醇双酯(PGMA/EDMA)树脂为载体,制备新型L-羟脯氨酸聚合物键合高效手性配体交换固定相。该固定相在配体交换分离模式下,以0.2mol/LNaAc和0.1mmol/LCu(Ac)2水溶液(pH5.2)为流动相,柱温为30℃～50℃,对衍生和非衍生的D,L-氨基酸和α-羟基酸等9种手性化合物进行了高效液相色谱拆分。详细考察了流动相pH值、温度、流速和进样量对手性分离的影响,选择了合适的色谱分离条件。结果表明,所拆分的9种手性化合物,有5种手性化合物能得到基线分离,最好的分离因子α=2.32。     

β-氨基酸对映体在键合型配体交换色谱固定相上的分离

制备了以L-α-氨基酸为手性配体和球型多孔硅胶为基质的键合型手性配体交换色谱固定相,用于β-氨基酸对映体的拆分。考察了硅胶基质、配体、流动相pH值、中心金属离子浓度和流动相阴离子等因素对5种β-苯丙氨酸对映体分离的影响,由此确立最佳色谱分离条件为以BaseLine硅胶为基质键合L-羟脯氨酸的手性固定相,5.0mmol/L和pH4.6的CuSO4溶液为流动相,紫外检测波长为254nm。在此条件下5种β-氨基酸对映体均可在35min内得到分离,分离因子在1.49~1.77之间。结果表明该方法操作简便,成本低廉,可用于β-氨基酸对映体的分离和分析。     

点击化学制备新型手性配体交换色谱固定相

采用点击化学反应制备了一种新型L-脯氨酰胺衍生物键合手性配体交换色谱固定相.硅胶与γ-氯丙基三乙氧基硅烷反应后,再与叠氮化钠反应制备得到叠氮化硅胶. 在甲醇溶液中,以溴化亚铜为催化剂,叠氮化硅胶与合成的手性选择子N-炔丙基脯氨酰胺,室温反应48 h,而键合上手性官能团.手性选择子的键合量达0.47 mmol/g,操作简单,反应条件温和.制备的手性固定相以0.2 mmol/L Cu(Ac)2水溶液为流动相,在配体交换模式下拆分了8种D,L-氨基酸,对映体选择因子α在1.14～2.42之间.手性分离能力和稳定性研究表明,点击化学在手性配体交换色谱固定相的制备中具有极大潜力.     

新型手性配体交换色谱固定相的合成及其对DL-氨基酸的拆分

将β-(3,4-环氧环己基)乙基三甲氧基硅烷与硅胶反应,得到环氧化硅胶中间体,然后与L-异亮氨酸反应,再与铜离子进行配位,最后得到一种新型配体交换固定相。用DL-氨基酸对该固定相进行了色谱评价,同时探讨了分离机理。研究结果表明,该固定相在配体交换模式下,可对DL-氨基酸进行良好分离。     

L-苯丙氨酸键合手性配体交换色谱固定相的制备及手性拆分

合成了L-苯丙氨酸键合手性配体交换固定相，用元素分析和红外光谱对固定相进行了表征；该固定相在反相条件下对DL-氨基酸对映体有良好的拆分能力。     

α-羟基酸在不同的手性配体交换色谱固定相上分离性能的考察

合成了L-羟基脯氨酸，L-脯氨酸，L-苯丙氨酸3种硅胶链合手性配体交换色谱固定相，并用于α-羟基酸的直接光学分离，取得了较为满意的结果。对不同的手性配体交换色谱固定相的分离性能进行了比较，并详细考察了流动相pH值、金属离子浓度、柱温等因素对分离效果的影响，从而进一步优化了色谱分离条件。     

改性的配体交换型手性固定相的合成及应用

通过在巯丙基硅胶表面引入苯乙烯长链,再加入甲基丙烯酸缩水甘油酯在聚苯乙烯链端进行延长,用L-脯氨酸和L-羟脯氨酸进行修饰的方法合成了两种聚合物型配体交换型手性固定相(CSPⅣ和CSPⅤ),并采用6种氨基酸对映体考察了合成固定相的色谱拆分效果。结果表明,除DL-脯氨酸外,其余氨基酸对映体均具有相同的出峰顺序,即D-异构体优先出峰。与不含聚苯乙烯单元的配体交换型手性固定相相比,CSPⅣ和CSPⅤ具有更小的保留因子,更好的对映体选择性和更高的分离度。     

L-异亮氨酸型配体交换固定相对DL-氨基酸的拆分研究

用自制的新型L-异亮氨酸配体交换固定相在配体交换模式下对11种DL-氨基酸进行了拆分研究,详细考察了流动相中铜离子浓度、甲醇含量、流速及温度对拆分效果的影响,并探讨了可能的拆分机理。研究结果表明:流动相中高浓度的铜离子不利于DL-氨基酸的拆分;增加流动相中甲醇的含量,降低流动相流速以及提高色谱柱温度均可改善拆分效果。     

Preparation of novel chiral stationary phase based on click chemistry for ligand exchange chromatography

Click chemistry was applied to immobilize L-proline derivative onto azide-modified silica gel to give a novel chiral stationary phase(denoted as click-CSP) for ligand exchange chromatography.The developed protocol combines the benefits of operational simplicity,exceptionally mild conditions and high surface loadings.The enantioselectivityαof some DL-amino acids on the click-CSP were found to be in the range from 1.13 to 3.46.The chromatographic resolutions of some DL-amino acids and the stability study f...     

一种新型手性配体交换色谱键合固定相

采用气相或液相色谱法拆分氨基酸对映体通常一化过程,费时而麻烦,而且有可能发生消旋,影响分析结果,手性配体交换色谱法是拆分氨基酸和羟基酸对映体的一种有效方法,其选择性高,不需柱前衍生。Davankov等对此方法进行了评述。此法大都采用刚性环状结构的光活性脯氨酸或羟基脯氨酸键合相作为柱填料,Jeanneret-Gris等曾采用1,2,3,4－四氢－3－异喹啉羧酸接枝的聚丙烯酰胺相拆分氨基酸对映体。     

新型手性配体交换色谱固定相的制备及应用

 合成了 2 -(2 -羟基 -3 -烷氧基 )丙基 -(S) -1 ,2 ,3 ,4-四氢 -3 -异喹啉羧酸手性选择子 ,制备了两种新型涂渍手性配体交换色谱固定相 ,拆分了某些 DL-氨基酸 ,比较了 DL-氨基酸在两种手性相上的色谱分辨。     

Chiral speciation and determination of DL-selenomethionine enantiomers on a novel chiral ligand-exchange stationary phase.

A new type of chiral ligand-exchange stationary phase (CLES) was successfully synthesized by treating silica gel with beta-(3,4-epoxycyclohexyl)ethyltrimethoxy silane and opening the epoxy ring by L-isoleucine. The chiral speciation of DL-selenomethionine (DL-SeMet) by high-performance liquid chromatography (HPLC) with UV absorbance on the CLES column was studied. The influences of the contents of copper ion and methanol as well as the pH value in the mobile phase and temperature of the column on the efficiency of resolution of DL-SeMet were investigated in detail. DL-SeMet could be completely resolved within 40 min under the optimal operating conditions of 0.1 mmol/L Cu2+ at 0.05 mol/L KH2PO4 buffer (pH = 5.5) and 35 degrees C temperature of the column. The limits of detection of D- and L-SeMet were 255 ppb and 286 ppb, respectively. This method was applied to determine the D- and L-enantiomers of DL-SeMet in real samples, such as selenized yeast powder and garlic.     

Chiral ligand-exchange chromatography of amino acids using porous graphitic carbon coated with a dinaphthyl derivative of neamine

In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl anchor system efficiently (1.15 μmol/m²) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids. Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase     

A chiral stationary phase with special hydrophobic framework for ligand-exchange chromatography

A novel chiral stationary phase (CSP1) for ligand-exchange chromatography (CLEC) was prepared by firstly using dimethyl- chlorosilane as an endcapping reagent for decreasing residual silanol group on the surface of silica gel,and then introducing L-Pro as a chiral selector and hydrophobic octyl group to the silica gel surface simultaneously.The enantioseparations of 14 DL-amino acids on CSP1 were achieved with the enantioselectivityαranging from 1.09 to 2.44 and the resolution Rs being between 0.8 and 6.3.The chromatographic performances of CSP1 with the bonded phase (CSP2) prepared using reference method were compared.The results showed that the column efficiency and resolution Rs of chiral stationary phase could be improved by using the above modifying method.     

Preparation and evaluation of a novel chiral stationary phase based on covalently bonded chitosan for ligand-exchange chromatography

A novel chiral stationary phase based on chitosan covalently bonded onto silica gels has been prepared and used for the separation of various alpha-amino acid enantiomers as well as alpha-hydroxycarboxylic acid enantiomers by chiral ligand-exchange chromatography with copper(II) as a complexing ion. The methanol content and copper(II) ion concentration in the eluent affected retentivity and enantioselectivity. Furthermore, a plausible chiral recognition mechanism for resolution of alpha-amino acids was proposed.