模拟移动床色谱技术及其应用

1 模拟移动床技术简介 模拟移动床(simulated moving bed,SMB)技术是20世纪60年代发展起来的一种现代化分离技术,它是由Broughton D.B博士发明①,并由美国UOP公司(Universal Oil Products Company,环球石油产品公司)首先应用于石油化学工业的一种色谱技术,具有分离效率高、流动相消耗低、设备体积小、便于自动化连续性生产等优点②.SMB技术的兴起为工业规模的分离提纯提供了一种崭新的有效途径,被认为是化工技术中的一次革新,其应用范围己由最初的石化领域逐步扩展到精细化工、生物发酵、食品及医药等领域.     

模拟移动床连续离交工艺在D-核糖发酵液净化中的应用

D- 核糖是存在于生物体内的一种天然戊糖,是生物体内遗传物质核酸和能量物质三磷酸腺苷(ATP)的组成成分,具有重要的生理功能和广泛的应用前景.     

完整分离围着床期小鼠子宫内膜方法的建立

目的　为了获得组织结构完整、功能正常的子宫内膜样本以进行胚胎着床的体外研究。方法　作者比较了剪碎法、刮取法和挤压法取得子宫内膜的效果。结果　挤压法得到的小鼠子宫内膜呈圆形条状;子宫内膜组织结构完整,具有内膜上皮并包含腺体、血管的基质;意外发现子宫系膜侧的子宫内膜缺损。结论　挤压法是获取子宫内膜进行相关研究的理想方法。     

顺序式模拟移动色谱纯化木糖醇母液北大核心CSCD

以木糖醇母液为原料,采用顺序式模拟移动色谱技术纯化木糖醇母液。在制备色谱研究的基础上,研究顺序式模拟移动床(SSMB)技术纯化木糖醇母液的最佳工艺参数。结果表明最佳工艺参数为:进料浓度60%,进料量为546.00 g/h,进水量为819.00 g/h,循环量382.2 m L。在此条件下木糖醇出口浓度为41.2%,纯度达到94.8%,收率达到90.6%,较木糖醇母液纯度提高31.12%,本研究为木糖醇母液产业化利用奠定了实践基础。     

分子模拟技术及其在生物分离中的应用

分子模拟技术是借助计算机进行微观过程观测的研究工具,广泛应用于生物、材料、化学、化工和物理等领域的研究.本文简要介绍分子模拟的基本流程,着重介绍模型构建和模拟方法,最后以疏水电荷诱导色谱界面过程的分子动力学模拟为例阐述分子模拟在生物分离中的应用     

母子分离应激对complexin Ⅱ基因缺陷鼠快速移动行为的影响

本文旨在探讨母子分离应激对complexin Ⅱ基因缺陷(Cplx2-/-)小鼠快速移动行为的影响。实验分4组:应激Cplx2-/-组、应激Cplx2+/+组、无应激Cplx2-/-组和无应激Cplx2+/+组。无应激组小鼠正常饲养,应激组小鼠从出生后第2日至第21日每天施加母子分离应激。小鼠生长到第4周时,利用聚合酶链反应技术检测其基因型。4组小鼠腹腔注射激动剂去氧麻黄碱或生理盐水后,采用EthoVision系统对小鼠快速移动行为进行记录。结果显示,应激Cplx2-/-组、应激Cplx2+/+组、无应激Cplx2-/-组和无应激Cplx2+/+组注射去氧麻黄碱后,与生理盐水对照组相比,均出现快速移动行为不同程度的增多(P<0.01);与无应激Cplx2-/-组相比较,应激Cplx2-/-组注射去氧麻黄碱后快速移动行为增多更为明显(P<0.001);与应激Cplx2+/+组相比,应激Cplx2-/-组注射去氧麻黄碱后的快速移动行为增多更为明显(P<0.001)。本实验证实小鼠的行为可能受母子分离应激和Cplx2基因等因素的多重影响。     

铜藻中β-丙氨酸的分离及结构鉴定

非蛋白质氨基酸在抗癌、抗菌、抗结核、抗坏血病等方面有着重要的作用。本文主要对铜藻中的游离氨基酸进行检测分析和部分分离纯化及结构鉴定方面的研究,为更好的开发利用这些天然产物提供技术支持。采用离子交换树脂层析法分离铜藻粗提液中的游离氨基酸,收集3 mol/L的氨水洗脱液,用PITC-HPLC柱前衍生反相高效液相色谱法对其进行检测分析,结果显示粗提液中除含有多种组成蛋白质的氨基酸外还有3种未知组分,且含量较高的常见蛋白质氨基酸为丙氨酸、脯氨酸、缬氨酸。采用半制备高效液相色谱系统制备分离了其中一种未知组分的衍生物MWZ2,经真空冷冻干燥后为略黄固体粉末,结合核磁共振波谱、高分辨质谱、红外光谱数据,最终鉴定MWZ2去掉已知取代基团PITC后的成分为β-丙氨酸,分子式为C3H7NO2,分子量为89.09。     

发酵床中纤维素降解菌的分离与鉴定

从发酵床垫料中初步分离出43株纤维素降解菌。采用刚果红鉴别培养基及滤纸条培养基初筛,得到5株透明圈较大且使滤纸条产生崩解的菌株,通过进一步液体发酵,测定其CMC酶活、FPA酶活和天然纤维素酶活,获得2株具有较高纤维素降解活性菌株,并分别命名为F7和F21。经16S rRNA基因序列分子生物学鉴定和系统发育分析表明,这2株纤维素降解菌分别归属为枯草芽孢杆菌(Bacillus subtilis)和链霉菌(Streptomyces sp.)。     

硅胶柱色谱分离纯化生物发酵液中叶酸的研究

采用硅胶柱色谱分离纯化生物发酵液中的叶酸 ,实验研究了色谱方法 ,确定了适的谱条件。     

Chiral separation of flurbiprofen enantiomers by preparative and simulated moving bed chromatography

This study presents the chiral resolution of flurbiprofen enantiomers by preparative liquid chromatography using the simulated moving bed (SMB) technology. Flurbiprofen enantiomers are widely used as nonsteroidal anti‐inflammatory drugs, and although demonstrate different therapeutic actions, they are still marketed as a racemic mixture. The results presented here clearly show the importance of the selection of the proper solvent composition for the preparative separation of flurbiprofen enantiomers. Chiral SMB separation is carried out using a laboratory‐scale unit (the FlexSMB‐LSRE®) with six columns, packed with the Chiralpak AD® stationary phase (20 μm). Results presented include the experimental measurement of equilibrium and kinetic data for two very different solvent compositions, a traditional high hydrocarbon content [10%ethanol/90%n‐hexane/0.01% trifluoroacetic acid (TFA)] and a strong polar organic composition (100%ethanol/0.01%TFA). Experimental data, obtained using the two mobile phase compositions, are used to predict and optimize the SMB operation. After selecting 10%ethanol/90%n‐hexane/0.01%TFA as the most appropriate solvent composition, three feed concentrations of racemic flurbiprofen were considered. Using 40 g/l of racemic flurbiprofen feed solution, the purities for both outlet streams were above 99.4%, the productivity was 13.1 g_feed/(L_bed h), and a solvent consumption of 0.41 L_solvent/g_feed was achieved. Chirality, 2011. © 2011 Wiley‐Liss, Inc.     

Preparative resolution of the enantiomers of tert-leucine derivatives by simulated moving bed chromatography

The enantiomers of two different derivatives of tert-leucine were separated by continuous chromatography on chiral stationary phases applying the simulated moving bed technique. About 1 kg of racemic N-carbobenzoxy-tert-leucine was resolved on the cellulose-based phase Chiralcel OD using a mixture of heptane/ethanol and 0.1% of trifluoroacetic acid modifier as the mobile phase, while 520 g of the N-Boc-tert-leucine-benzylester was resolved on the amylose-based phase Chiralpak AD with a mixture of heptane/2-propanol as the mobile phase. In both instances the corresponding enantiomers were obtained in high yield and high optical purity.     

Separation of amino acids by simulated moving bed using competitive Langmuir isotherm

The separation of two amino acids, phenylalanine and tryptophan, was carried out using laboratory simulated moving bed (SMB) chromatography. The SMB process consisted of four zones, with each zone having 2 columns. The triangle theory was used to obtain the operating conditions for the SMB. The mass transfer coefficients of the two amino acids were obtained from the best-fit values by comparing simulated and experimental pulse data. The competitive adsorption isotherms of the two amino acids were obtained by single and binary frontal analyses, taking into consideration the competition between the two components. A competitive Langmuir isotherm, obtained from single-component frontal chromatography, was used in the first run, and the isotherm from binary frontal chromatography in the second, with the flow rate of zone I modified to improve the purity. Compared to the first and second runs, the competitive Langmuir isotherm from the binary frontal chromatography showed good agreement with the experimental results. Also, adjusting the flow rate in zone I increased the purity of the products. The purities of the phenylalanine in the raffinate and the tryptophan in the extract were 99.84 and 99.99%, respectively.     

Isolation of potato proteins using simulated moving bed technology

The simulated moving bed (SMB) concept of chromatography was applied to treat potato juice from production of starch. The aim was to harvest proteins. SMB offers possibilities to operate with different process strategies and in this study it was shown possible to harvest up to 80% of the protein in a process utilizing very little extra water besides that already present in the juice. After depleting protein from the juice in the adsorption step, the flow through was used to recondition the column after elution. The present study illustrates a new concept of applying chromatography as a capturing step of bulk products.     

Comparing the performance of one-column process and four-zone simulated moving bed by computer simulation

A new one-column chromatography process, analogous to a four-zone simulated moving bed (SMB), was presented. The basic principle of the process was identical to that of a four-zone SMB. The process consisted of one chromatographic column and four tanks, instead of the four columns in the four-zone SMB (1-1-1-1), and has been used for the separation of two amino acids, phenylalanine and tryptophan, using an ion exchange resin. The operating parameters for the one-column process and four-zone SMB were obtained from equilibrium theory. Computer simulations were used to compare the performances of the new one column process to that of the general four-zone SMB, using Aspen Chromatography^™ v 11.1. The differences between the one-column and SMB processes in terms of the purities and yields of phenylalanine and tryptophan were less than 4 and about 6%, respectively. The lower purities of the one-column process were due to the loss of the developed concentration profiles in the column when the liquid was stored in tanks. The one-column process gave great flexibility, and would be useful for reconstructing an existing conventional chromatography process to one of a SMB.     

Optimal operating mode for enantioseparation of SB-553261 racemate based on simulated moving bed technology

The performance of the simulated moving bed (SMB) technology and its modification, the Varicol process, was optimized using an experimentally verified model for the enantioseparation of SB-553261 racemate. Single and multiobjective optimizations have been carried out for both existing as well as design stage and their efficiencies were compared. The optimization problem involves a relatively large number of decision variables, both continuous variables such as flow rates, switching time and length of the columns, as well as discrete variables like number and distribution of columns. A state-of-the-art new optimization technique based on a genetic algorithm (nondominated sorting genetic algorithm with jumping genes) was utilized which allows handling of these complex optimization problems. The optimization results showed that significant improvement could be made to the chiral drug separation process using both the SMB and the Varicol process. It was found that the performance of a Varicol process is superior to that of a SMB process in terms of treating more feed using less desorbent or increasing productivity while at the same time achieving better product quality. Optimum results were explained using equilibrium theory by locating them in the pure separation region.     

Preparative scale enantioseparation of a chiral epoxide: Comparison of liquid chromatography and simulated moving bed adsorption technology

The feasibility of using simulated moving bed technology (SMB) for chiral separation on cellulose triacetate is demonstrated on the preparative scale: 1 kg of a chiral epoxide has been separated. On comparing SMB technology with conventional liquid chromatography it turns out that the main advantage of SMB lies in the significant reduction of mobile phase consumption. The process design for SMB is made theoretically and the predictions are confirmed by our pilot study. © 1993 Wiley-Liss, Inc.     

Development of a three-zone simulated moving bed process based on partial-discard strategy for continuous separation of valine from isoleucine with high purity,high yield,and high product concentration

The issue of separating valine from isoleucine has been a major concern in the biotechnological process for production of valine. To address this issue, an optimal three-zone simulated moving bed (SMB) process for continuous separation of valine was developed in this study. It was first found that an Amberchrom-CG161C resin was highly suitable for the adsorbent of such SMB process. The adsorption isotherm and mass-transfer parameters of valine and isoleucine on the Amberchrom-CG161C adsorbent were then determined through multiple frontal experiments. The determined parameters were used in the next stage of optimizing the SMB for valine separation, which was performed on the basis of genetic algorithm. For the optimized SMB process, a partial-discard strategy was applied to the raffinate port in order to make a further improvement in the valine product concentration. Finally, the optimized SMB based on the partial-discard strategy was tested experimentally using the self-assembled SMB equipment. The experimental results showed that the developed process in this study was highly effective in continuous separation of valine from isoleucine while ensuring the attainment of high product concentration. The experimental data for the SMB effluent histories and the SMB column profiles were also in close agreement with the model predictions.     

A novel design of simulated moving bed (SMB) chromatography for separation of ketoprofen enantiomer

A simulated moving bed (SMB) chromatography system is a powerful tool for preparative scale separation, which can be applied to the separation of chiral compound. We have designed our own lab-scale SMB chromatography using 5 HPLC pumps, 6 stainless steel columns and 4 multi-position valves, to separate a racemic mixture of ketoprofen in to its enantiomers. Our design has the characteristics of the low cost for assembly for the SMB chromatography and easy repair of the unit, which differs from the designs suggested by other investigators. It is possible for the flow path through each column to be independently changed by computer control, using 4 multi-position rotary valves and 5 HPLC solvent delivery pumps. In order to prove the operability of our SMB system, attempts were made to separate the (S)-ketoprofen enantiomer from a ketoprofen racemic mixture. The operating parameters of the SMB chromatography were calculated for ketoprofen separation from a batch chromatography experiment as well as by the triangle theory. With a feed concentration of 1 mg/mL, (S)-ketoprofen was obtained with a purity of 96% under the calculated operating conditions.