Thin-Layer Chromatographic Separation of Amino Acid Enantiomers using Ligand Exchange

Silica gel thin-layer plates covered with L-arginine and copper acetate were used for the separation of amino acid enantiomers, The chromatographic selectivity and the effects of plate different preparation methods, sample molecular structure and solvent compositions on resolution performance were also discussed.

Separation of Neutral Amino Acids with Ligand Exchange Resins

Four neutral amino acids (Gly, Ala,.Val and Leu) were separated with ligand exchange resins. The separation capacity of the ligand exchange resins is compared with that of common ion exchange resins. The effects of eluent, column temperature, and central metal ions of the support on the separation are studied. The relationship between matrix structure of resins and their separation capacity is analysed.

Investigation of Mixed Chiral Selectors of Different Metal Ion-L-Alanine Complex and β-Cyclodextrin on the Chiral Separation of Dansyl Amino Acids with Capillary Electrophoresis

Chiral separation of dansyl amino acids by capillary electrophoresis using mixed selectors of Mn(II)- L -alanine complex and β -cyclodextrin ( β -CD) was studied. Resolution was considerably superior to that obtained by using either Mn(II)- L -alanine complex or β -CD alone. The effects of separation parameters,such as pH value of buffer solution,capillary temperature,the concentration of Mn(II)- L -alanine complex,the types of CD and ligand on the migration times and resolutions were investigated. Six different transition metal complexes, Cu(II), Zn(II),Co(II),Ni(II),Hg(II) and Cd(II)- L -alanine complexes have been employed and compared with Mn(II) complex. Differences in retention and selectivity were found. The substitution of Cu(II),Zn(II),Co(II) and Ni(II) for Mn(II) resulted in a better chiral resolution while Hg(II) and Cd(II) showed poorer resolution abilities. The chiral separation mechanism was also discussed briefly.

Enantiomeric Separation of Amino Alcohols by Ion-pair Chromatography

Enantiomers of four amino alcohols were resolved by ion-pair chromatography with (+)-10-camphorsulphonic acid as chiral counter ion. Studies of the influence of the mobile phase composition, the solute structure and the mobile phase flow-rate on separation are presented. Under the optimized conditions enantiomeric propanolol, norephedrine, metropolol and salbutamol were separated using dichloromethane-1-pentanol (97:3 v/v) as mobile phase on Lichrospher-100-DIOL column.

STUDY ON THE SEPARATION OF GLUTAMIC ACID BY ION-EXCHANGE

The feasibility of recavering glutamic acid by ion exchange method with macroporous resins was investigated. Their adsorption properties in static state and the effective factors,such as pH, concentration of feed and the ratio of ammonium ion toglutamic acid,were systematically explored. The best conditions of separating glutamic acid from mother liquid were obtained.

Impact of Hydrogen Ion Concentration on Amino Acids Composition of Macadamia Protein: Approached Using Cation-Exchange Chromatography

In the present context, the objective of this study was to synthesize and analyze the content of AA of macadamia protein and the impact of hydrogen ion concentration (pH) on AA composition. The determination of AA mainly by cation-exchange chromatography was also investigated. Reproducible and reliable techniques for quantification and identification of AA usually require derivatization. However, techniques such as AA analyzer are composed of cation-exchange chromatography and other components can sideline the derivatization with significant accuracy. The present analysis revealed a higher concentration of essential amino acids especially acidic AA, Glu and Asp and basic AA, Arg than other AA in macadamia protein. The study constitutes first report of use of bubble chart for evaluation of AA and explaination of AAS. The results may elaborate that the degradation of AA of macadamia protein for extraction of pH 11 is caused by the impact of pH. Moreover, the nutritional values of AA present in macadamia protein could change for the better by adjusting pH of extraction.

The Synthesis of Cyclic Amino Acids

Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds.

Amino Acid Composition of Tightly Bound Exopolymeric Substances Produced by Corrosion-Related Bacteria in Presence of Mild Steel

The composition of tightly bound exopolymeric substances (EPS) obtained from biofilm and plan- ktonic cell subpopulations of Stenotrophomonas maltophilia 5426 UKM was analyzed to study an impact of mild steel presence in the cultivation medium. The overall protein production was found to increase in the presence of a steel coupon. Some amino acids such as lysine, valine, iso-leucine, tyrosine and phenylalanine were found to be secreted in higher amounts in the presence of mild steel, while its absence leads to an increase of arginine, asparagine, serine, glutamine, proline, glycine, cysteine, leucine, methionine production levels. Biofilm cells EPS contained more arginine, glycine, cysteine, valine, methionine and leucine, comparing to EPS of planktonic cells. The chang- es of tightly bound EPS aggregation around the cells induced in the presence of steel coupons were revealed by transmission electron microscopy. The results suggested the transition of S. maltophilia 5426 UKM cells from planktonic to biofilm lifestyle to be a complex process involving more than a single step.

Concentration of Hydrochloric Acid by Pervaporation Membrane Separation Process

Hydrogen chlorid (HC1) used in chemical industry and laboratory is usually obtainedfrom concentrated hydrochloric acid (approximately 37% of HC1) through distillation,When the hydrogen chloride content in concentrated hydrochloric acid is extracted

铜污酸中铼的分离提取研究进展

铼是一种战略性金属,在军工、航天及航空领域具有重要的地位,由于其独特的性质成为了航空航天发动机中不可或缺的材料.铼金属几乎没有独立矿床,其资源主要伴生于铜、钼等金属矿中.铜矿中铼资源经过铜冶炼工序后富集到废弃的污酸当中,从污酸中回收铼成为铼冶金的重要研究内容.本文综述了污酸中铼提取的主要技术难点,对现有的分离提取方法进行了阐述及对比,主要包括化学沉淀法、溶剂萃取法、离子交换法、吸附法等,分析了各技术现阶段存在的问题,为污酸中铼的分离提取技术发展提供参考.最后展望未来,污酸中铼的分离提取应向绿色环保、短流程、高选择性的方向发展.

STUDY ON THE ISOTHERMS OF THE INTERACTION BETWEEN SUSPENDED PARTICLES AND Cu (Ⅱ) IN THE HUANGHE RIVER

The isotherms of the interaction between the suspended particles and Cu 2+ ,and the effects of lysine and asparaginic acid on the isotherms in the Huanghe (Yellow) River were studied by applying the theory and method of interfacial stepwise ion/coordination particle exchange. We obtained a new stepped river isotherm, formed by two curves joined together with a “plateau” in the middle. The adsorption equilibrium constants K 1 and K 2 were calculated by using the isothermal equation of surface stepwise ion exchange. Amino acid in small amount promotes exchange adsorption of the suspended particles with Cu 2+ . The degree of promotive action relates to the isoelectric point of amino acid. The promotive effect of lysine is bigger than that of asparaginic acid.

离子交换色谱法测定饲料中含硫氨基酸含量的不确定度评定

试验采用离子交换色谱法测定饲料中含硫氨基酸的含量,对含硫氨基酸检测结果的不确定度进行计算和评定。试验建立了数学模型以对整个试验过程的不确定度进行来源分析,计算合成不确定度和扩展不确定度。结果显示,牧草粗饲料中胱氨酸的含量为0.39 g/100 g,扩展不确定度为0.02 g/100 g (k=2);蛋氨酸的含量为0.21 g/100 g,扩展不确定度为0.02 g/100 g (k=2),方法回收率和标准溶液配制的不确定度贡献较大,是测量误差的主要来源。研究表明,试验建立的不确定度评定方法可为饲料中含硫氨基酸含量的质量控制提供参考。

酸盐分离技术在镍电积阳极液中的应用

目前酸盐分离技术主要有树脂吸附法、离子交换法和膜分离技术三大类,但将其应用于镍湿法冶炼中镍电积阳极液的报道较少。总结了三大类酸盐分离技术的原理和应用,并分别采用树脂吸附法、扩散渗析法、特种纳滤膜和电渗析结合的方法对镍电积阳极液进行酸盐分离试验。结果表明,三种方法对镍电积阳极液均有一定的分离效果,其中树脂吸附法易饱和,需反洗再生,造成体积膨胀;扩散渗析法对硫酸的回收率在80%以上,镍的截留率在90%以上,但回收的硫酸浓度较低,同样存在体积膨胀问题;特种纳滤膜和电渗析结合法对镍离子的截留率可达90%以上,氢离子去除率可达70%以上,同时浓缩后的氢离子浓度可提高400%以上,镍离子浓度可提高500%以上,淡化液中各种离子浓度小于50 mg/L,可用作纯水,并且该方法不会造成系统体积膨胀,具有工业化应用价值。

有毒、生化难的阻燃剂四溴双酚A生产废水优化处理的研究

针对阻燃剂四溴双酚A生产综合废水组成复杂、具有刺激性有毒气味、难以生化降解的特点,采用资源化为主体的优化处理模式,使用顶空气相色谱仪、气相色谱-质谱联用仪(GC-MS),调查废水中难以生化降解的组成,根据实际生产工艺,构建酸化分离、絮凝净化、活性炭吸附以及离子交换深度处理,实现对实际四溴双酚A生产综合废水的有效处理。实验结果表明,综合废水中含有的有机物主要有甲苯、氯苯、2,4-二溴苯酚、2,6-二溴苯酚和2,4,6-三溴苯酚,其中2,4,6-三溴苯酚具有强烈的刺激性气味和毒性;酸化分离过程的pH最佳操作条件为3.1,此时酸析出对以上五种物质的去除率分别为81.0%、70.7%、64.76%、54.26%和90.52%,固体物每升回收5.2 g,有效降低了后续处理的负荷;絮凝净化去除酸析出过程悬浮在污水中的微小颗粒物,其去除率分别为55.4%、14.9%、0%、0%以及14.1%,上清液的浊度达到1.8 NTU;活性炭吸附的去除率分别为3.1%、81.23%、99.75%、100%和92.41%,刺激性气味已基本消除;最后离子交换深度处理的去除率分别为3.1%、100%、100%、100%和100%,上清液无色无味、清澈透明,为阻燃剂生产废水的有效处理提供了一个重要途经。

强酸型离子交换纤维PVF-g-SO_3H对碱性氨基酸的分离研究

研究强酸型阳离子交换纤维PVF g SO3 H对碱性氨基酸L 组氨酸和L 赖氨酸的吸附分离性能 ,并与 73 2号树脂进行比较 .结果表明PVF g SO3 H纤维不仅对单组份赖氨酸或组氨酸的吸附率比 73 2号树脂高约 1 5%～ 3 9% ,而且其洗脱率高约 1 2 5%～ 1 3 4 % ,同时对混合氨基酸的洗脱峰既强而且分辨率高 .再生后纤维和树脂的总提取率都有微小的下降 ,但纤维的再生提取率仍高于 73 2号树脂 1 0 %以上 .实验的最佳洗脱条件为 :洗脱液柠檬酸 柠檬酸钠的pH值为 4 6,填充柱长径比为 2 0 ,洗脱速率为 1mL/min .

用低交换容量聚苯乙烯型强酸性阳离子交换树脂柱色谱分离中性氨基酸

通过磺化苯乙烯 -二乙烯苯共聚物或商品化的聚苯乙烯型强酸性阳离子交换树脂 ( 0 0 1× 7)的逆磺化反应 ,得到一系列不同交换容量的聚苯乙烯型强酸性阳离子交换树脂 .研究了丙氨酸和缬氨酸及缬氨酸和亮氨酸在这些树脂柱上的色谱分离 .结果表明 ,用两种方法得到的树脂对丙氨酸和缬氨酸的色谱分离性能基本相同 ;同时中性氨基酸与聚苯乙烯型强酸性阳离子交换树脂之间的作用包括离子作用和疏水作用 ,且二者之间存在协同作用 .

离子交换纤维分离混合氨基酸的性能研究

对新研制的强酸型离子交换纤维PP-g-St-SO3H和两性离子交换纤维PP-g-4VP-SO3H分离混合氨基酸的性能进行研究,并与相应的离子交换树脂进行比较。结果表明在相同分离操作条件下,所制备的阳离子交换纤维PP-g-St-SO3H和两性离子交换纤维PP-g-4VP-SO3H对混合氨基酸的分离性能比通用732#树脂好。两性离子交换纤维还具有洗脱容易,洗脱液用量少的特点。在合适条件下,PP-g-St-SO3H纤维分离组氨酸和谷氨酸的分辨率达1.87。PP-g-4VP-SO3H两性纤维分离丙氨酸和谷氨酸的分辨率达2.69。

氨基酸的提取与精制

综合介绍了氨基酸提取过程中常用的分离技术以及近期的发展动态。如沉淀法、离子交换法、膜分离法和萃取法。并提出了氨基酸提纯精制的关键环节—结晶过程中应该注意的问题。

氨基酸分离纯化的研究进展

总结了氨基酸分离纯化过程中常用的技术,如沉淀法、离子交换法、萃取法和膜分离法,介绍了各种技术的基本原理、特点和发展动态。

黄河水中悬浮粒子对镉离子的交换吸附等温线

研究了黄河水中悬浮粒子对 Ｃｄ２ ＋ 的交换吸附等温线以及赖氨酸和门冬氨酸对吸附作用的影响．研究结果得到一类具有一个“拐点”、两个“平台”的新型河流等温线，用分级离子交换等温式求出平衡常数 Ｋ１ 和 Ｋ２ ．当低浓度的氨基酸存在时，对镉与悬浮粒子的交换吸附起促进作用．促进作用的程度与氨基酸的等电点有关，赖氨酸的促进作用较门冬氨酸大．