基于二元手性选择剂协同作用的毛细管电泳拆分氨基酸对映体研究

氨基酸的手性拆分在生命的起源、发育、病变及衰老研究中均有重要的意义．虽然已有基于色谱和毛细管电泳的拆分方法,但由于氨基酸种类繁多,性质各异,因而具有广泛拆分能力的普适性拆分方法还很有限．组合运用手性选择剂是提高手性分离选择性和分离度的一种有效的方法［1-3]．为此,我们以毛细管电泳－激光诱导荧光检测（CE－LIF）为分析手段,研究了手性选择剂的添加组合,获得了一些具有一定广谱拆分性能的二元手性选择剂协同体系．本文以β-环糊精（β-CD）和牛磺胆酸钠（STC）为拆分体系,对20种氨基酸的异硫氰酸酯荧光素（FITC）衍生物进行手性拆分,分离度均在1．9     

手性金属有机笼MOC-PA作为毛细管电泳手性固定相

报道了一种手性金属有机笼[Cu₁₂(L_PA)₁₂(H₂O)₁₂]（PA=L-苯丙氨酸, MOC-PA)作为毛细管电泳分离新型固定相的研究. 采用X射线粉末衍射仪、 红外光谱、 热重分析和扫描电子显微镜对该材料进行了表征, 结果表明该手性金属有机笼具有良好的热稳定性和空间结构. 利用该材料制备的毛细管色谱柱具有良好的手性识别能力, 可拆分1,2-二苯基乙二醇、 佐匹克隆、 4-甲基二苯基甲醇和茴香偶姻等手性药物, 也能拆分位置异构体硝基苯酚. 通过对拆分1,2-二苯基乙二醇、 佐匹克隆、 4-甲基二苯基甲醇和茴香偶姻进行最佳条件的探究, 得出电压、 缓冲溶液浓度及pH值在毛细管电泳中对手性样品分离度的影响. 采用佐匹克隆进行毛细管柱的重现性研究表明, 用该材料制备的毛细管电泳色谱柱具有一定的稳定性和重现性. 可见, 金属有机笼是一种良好的毛细管电泳手性固定相, 有一定的手性拆分能力, 在色谱分离中有较好的发展前景.     

羧甲基聚合-β-环糊精作为选择剂应用于毛细管电泳法拆分手性化合物

提出了一种用毛细管电泳拆分3种未衍生化的氨基酸对映体(苯丙氨酸,酪氨酸,色氨酸)和一种手性药物(芬氟拉明)的方法.以水溶性羧甲基聚合-β-环糊精为手性选择荆,采用毛细管区带电泳模式,考察了手性选择剂浓度、缓冲溶液pH值、柱温及电压对分离的影响.4种手性化合物在各自优化的试验条件下,均达到基线分离.此法操作简单,可用于这4种手性化合物的质量控制.     

配体交换毛细管区带电泳拆分未衍生化氨基酸

以铜(Ⅱ)-L-谷氨酸络合物为手性分离选择剂,对苯丙氨酸、酪氨酸和色氨酸3种非衍生芳香族氨基酸的手性对映体拆分进行了研究,建立了一种快速、简便拆分未衍生化的氨基酸对映体的配体交换毛细管电泳方法.在使用10 mmol/L NH4AC(pH 5.0),5 mmol/L CuSO4和10 mmol/L L-谷氨酸的条件下,成功地拆分了苯丙氨酸、酪氨酸手性对映体;色氨酸手性对映体也得到部分分离;考察了电泳缓冲液组成、pH值等影响分离效果的因素.     

万古霉素键合手性固定相的制备与评价

大环抗生素作为一种新型的手性选择器,与高效液相色谱(HPLC)、毛细管电泳(CE)和毛细管电色谱(CEC)等联用,成功分离各类手性化合物~([1～3]).自1994年Armstrong等~([4])首次将大环糖肽抗生素作为手性选择器合成手性固定相以来,适用于手性分离的大环糖肽抗生素键合固定相的制备与应用得到飞速发展.本研究以万古霉素为手性选择剂,制备了万古霉素键合手性固定相液相色谱柱.采用反相高效液相色谱法对谷氨酸对映体进行了拆分,并考察了流动相条件对对映体拆分的影响.     

糊精介质中西替利嗪对映体的毛细管电泳拆分与定量测定

1引言盐酸西替利嗪(Cetirizine hydrochloride,CTRZ)是第二代H1受体拮抗剂,结构中有一个手性碳原子,其抗组胺活性来源于左旋体。手性柱的HPLC方法对CTRZ的拆分已有报道,但成本较高,不利于推广。以毛细管电色谱方法拆分,但分离度不尽人意。目前在毛细管电泳手性拆分领域,环糊精(     

酶反应动力学及人血清中手性氨基酸的LIE-CE研究

手性分析在生命起源研究、生命科学研究、药物研究、疾病研究、食品研究等领域中具有极其重要的研究意义.近年来,手性离子配体交换技术在手性氨基酸的分析的应用备受关注.本研究建立了了以Zn(Ⅱ)为中心离子的手性氨基酸离子配体交换毛细管电泳方法(LIE-CE)及氨基酸的丹酰氯在线衍生技术,并进一步开展了人血清中手性氨基酸的分析及酶反应动力学的研究.     

手性药物哌醋甲酯和沙丁胺醇的毛细管电泳分离

１引言手性药物的拆分一直是色谱领域的研究热点。毛细管电泳的高效、快速、运行成本低的优点为手性化合物的拆分提供了高效的分离方法。哌醋甲酯和沙丁胺醇分别是一种抗抑郁药和支气管扩张剂，常以外消旋体的形式在市场销售。本文以环糊精及其衍生物为手性选择剂，在毛细管区带电泳分离模式下拆分了手性药物哌醋甲酯（ｍｅｔｈｙｌｐｈｅｎｉｄａｔｅ）和沙丁胺醇（ａｌｂｕｔｅｒｏｌ），考察环糊精类型和浓度、缓冲溶液性质、分离电压以及有机添加剂等对两种手性药物分离的影响，其中哌醋甲酯对映体为毛细管电泳首次拆分。２实验部分２．…     

MAH-β-CD的合成及其在毛细管电泳手性拆分中的应用

合成了顺丁烯二酸酐-β-环糊精(MAH-β-CD),并通过红外光谱、质谱对其结构进行表征。以20 mmol/L乙酸铵为缓冲溶液,MAH-β-CD作为手性选择剂,利用毛细管电泳对氨基酸和手性药物对映体进行拆分研究。考察了缓冲溶液pH、分离电压和手性选择剂浓度等对拆分效果的影响,在优化条件下,成功拆分了3种氨基酸(DL-甲硫氨酸、DL-精氨酸、DL-赖氨酸)和两种手性药物(沙丁胺醇、氯美扎酮)对映体,分离度分别为5.11,5.55,2.99,2.33和1.64。     

涂层技术在毛细管电泳手性分离中的应用

手性是自然界的本质属性之一。手性分离分析技术对生命科学、环境科学、生物工程和药物工程等许多学科都具有十分重要的意义。当前,对不同种类手性化合物进行拆分已成为毛细管电泳技术最具特色的研究和应用领域之一。然而,被分析物(或拆分剂)在毛细管内壁的吸附是毛细管电泳手性分离中的常见问题。涂层技术就是采用不同的方法对毛细管内壁进行改性,是抑制非特异性吸附、提高分离效率及分离重现性最简便和最有效的方法。本文主要综述了近十几年来各种涂层技术在毛细管电泳手性分离领域的应用现状,并对毛细管涂层技术今后的发展进行了展望。     

Chiral separation of amino acids and peptides by capillary electrophoresis

Chiral separation of amino acids and peptides by capillary electrophoresis (CE) is reviewed regarding the separation principles of different approaches, advantages and limitations, chiral recognition mechanisms and applications. The direct approach details various chiral selectors with an emphasis on cyclodextrins and their derivatives, antibiotics and chiral surfactants as the chiral selectors. The indirect approach deals with various chiral reagents applied for diastereomer formation and types of separation media such as micelles and polymeric pseudo-stationary phases. Many derivatization reagents used for high sensitivity detection of amino acids and peptides are also discussed and their characteristics are summarized in tables. A large number of relevant examples is presented illustrating the current status of enantiomeric and diastereomeric separation of amino acids and peptides. Strategies to enhance the selectivity and optimize separation parameters by the application of experimental designs are described. The reversal of enantiomeric elution order and the effects of organic modifiers on the selectivity are illustrated in both direct and indirect methods. Some applications of chiral amino acid and peptide analysis, in particular, regarding the determination of trace enantiomeric impurities, are given. This review selects more than 200 articles published between 1988 and 1999.     

Recent developments in chiral capillary electrophoresis and applications of this technique to pharmaceutical and biomedical analysis

This paper provides an overview of the current status of chiral capillary electrophoresis (CE). The emphasis is placed on the application of CE in chiral separation of various racemic compounds. During the last two years about 280 papers, several review articles, and two entire issues, edited by S. Fanali (Electrophoresis 1999, 20, 2577-2798, and H. Nishi and S. Terabe (J. Chromatogr. A 2000, 879, 1-471.) have been devoted to chiral CE. Enantiomeric separations of various compounds, e.g., pharmaceuticals, drug candidates, drugs and related metabolites in biological fluids, amino acids, di- and tri peptides, pesticides and fungicides, have been performed using different chiral selectors. Native and derivatized cyclodextrins continue to be the most widely used chiral selectors. Other chiral selectors such as natural and synthetic chiral micelles, crown ethers, chiral ligands, proteins, oligo- and polysaccharides, and macrocyclic antibiotics have also been applied to chiral CE separations.     

Chiral separation of fluorescamine-labeled amino acids using microfabricated capillary electrophoresis devices for extraterrestrial exploration

Chiral separations of fluorescamine-labeled amino acids are characterized and optimized on a microfabricated capillary electrophoresis (CE) device. A standard mixture of acidic and neutral amino acids is labeled with fluorescamine in less than 5 min and the hydroxypropyl-beta-cyclodextrin (HPbetaCD) concentration, temperature, and pH are optimized (15 mM HPbetaCD, 6 degrees C, pH < 9) to achieve high-quality and low background chiral separations in less than 200 s. All four stereoisomers formed in the labeling reaction of the chiral dye with the chiral amino acids are typically resolved. At pH > 9, isomerization of the dye chiral center is observed that occurs on the time scale of the chip separation. Typical limits of detection are approximately 50 nM. These results demonstrate the feasibility of combining fluorescamine labeling of amino acids with microfabricated CE devices to develop low-volume, high-sensitivity apparatus and methods for extraterrestrial exploration.     

Separation of enantiomers in capillary electrophoresis with contactless conductivity detection

Contactless conductivity detection is successfully demonstrated for the enantiomeric separation of basic drugs and amino acids in capillary electrophoresis (CE). Derivatization of the compounds or the addition of a visualization agent as for indirect optical detection schemes were not needed. Non-charged chiral selectors were employed, hydroxypropylated cyclodextrin (CD) for the more lipophilic basic drugs and 18-crown-6-tetracarboxylic acid (18C6H4) for the amino acids. Acidic buffer solutions based on lactic or citric acid were used. The detection limits were determined as 0.3 microM for pseudoephedrine as an example of a basic drug and were in the range from 2.5 to 20 microM for the amino acids.     

Synthesis and application of dehydroabietylisothiocyante as a new chiral derivatizing agent for the enantiomeric separation of chiral compounds by capillary electrophoretic

A new chiral derivatizing reagent, dehydroabietylisothiocyante (DHAIC), was synthesized and used for the enantiomeric separation of chiral compounds in capillary electrophoresis (CE). The synthetic route to obtain DHAIC is described. The separation conditions for the chiral separation of several chiral compounds, such as protein amino acids and chiral drug DOPA were optimized. Best results for the chiral separation of DHAIC derivatized amino acids and DOPA were obtained in a running buffer consisted of 50 mM borate (pH 9.5), 5 mM sodium dodecyl sulphate (SDS) and 20% acetonitrile for amino acids and 60 mM Na₂HPO₄ (pH 8.0), 17 mM SDS and 25% acetonitrile for DOPA. Under the conditions studied, chiral separation of five amino acids including Ser, Val, Ala, Thr, Cys and a chiral drug DOPA as their diastereomeric DHAIC derivatives has been achieved by micellar electrokinetic chromatography (MEKC).     

Separation of aminoalkanephosphonic acid enantiomers by indirect UV detection capillary electrophoresis with application of cyclodextrins

Indirect UV detection capillary electrophoresis (CE) was used for the separation of aminoalkanephosphonic acid (AP) enantiomers by applying commercially available cyclodextrins as chiral discriminators. The results show that the separation of the enantiomers depends on pH of the background electrolyte, the molar ratio of cyclodextrin to aminophosphonic acid, and on the type of the applied chiral selector. Optimization of process conditions allowed enantiomeric baseline separation or partial separation of 12 out of 14 alpha-aminophosphonic acids studied. This type of CE might therefore be successfully used for routine determination of enantiomeric purity of aminophosphonic acids.     

Recent advances of capillary electrophoresis in pharmaceutical analysis

This review covers recent advances of capillary electrophoresis (CE) in pharmaceutical analysis. The principle, instrumentation, and conventional modes of CE are briefly discussed. Advances in the different CE techniques (non-aqueous CE, microemulsion electrokinetic chromatography, capillary isotachophoresis, capillary electrochromatography, and immunoaffinity CE), detection techniques (mass spectrometry, light-emitting diode, fluorescence, chemiluminescence, and contactless conductivity), on-line sample pretreatment (flow injection) and chiral separation are described. Applications of CE to assay of active pharmaceutical ingredients (APIs), drug impurity testing, chiral drug separation, and determination of APIs in biological fluids published from 2008 to 2009 are tabulated.     

Chiral determination of amino acids by capillary electrophoresis and laser-induced fluorescence at picomolar concentrations

In this publication we present results on the determination of enantiomers of amino acids at very low concentrations. A fluoresceine-based chiral dye was synthesized to allow the separation of diastereoisomers of D- and L-amino acids. We used capillary electrophoresis with different non-ionic surfactants (Brij). The separation parameters were optimized and separations of D- and L-isovaline, an unusual terrestrial amino acid, were obtained. The sensitivity limits were also determined using a commercial laser-induced fluorescence detector. The quantitation of these amino acids is very important to understand the process of chiral selection on Earth.     

Determination of amino acids in rat vitreous perfusates by capillary electrophoresis

In vivo determinations of amino acids are important for improving our understanding of physiological states of biological tissue function and dysfunction. However, the chemically complex matrix of different biological fluids complicates the assay of this important class of molecules. We introduce a method for characterizing the amino acid composition of submicroliter volumes of vitreous humor perfusates. Low-flow push-pull perfusion sampling is compatible with collecting small volume samples in a complicated matrix that are potentially difficult to separate. An efficient, sensitive, and rapid analysis of amino acids from in vivo perfusates of the vitreous is presented with 3-(4-carboxybenzoyl)-2-quinoline-carboxaldehyde (CBQCA) derivatitation and capillary electrophoresis (CE) separation with laser-induced fluorescence detection (LIF). Derivatization with CBQCA for up to 2 h provided high sensitivity and low detection limits at the nM level. Seventeen amino acids including D-serine (D-Ser) and D-aspartate (D-Asp) were resolved in less than 10 min. Importantly, D-Ser is separated from its enantiomeric pair. Characterization of vitreal amino acids with this assay technique will be useful for understanding ocular diseases and physiological mechanisms in vision.     

Azithromycin as a new chiral selector in capillary electrophoresis

In capillary electrophoresis (CE), separation of enantiomers of a chiral compound can be achieved through the chiral interactions and/or complex formation between the chiral selector and the enantiomeric analytes on leaving their diastereomeric forms with different stability constants and hence different mobilities. A great number of chiral selectors have been employed in CE and among them macrocyclic antibiotics exhibited excellent enantioselective properties towards a wide number of racemic compounds. The use of azithromycin (AZM) as a chiral selector has not been reported previously. This work reports the use of AZM as a chiral selector for the enantiomeric separations of five chiral drugs and one amino acid (tryptophan) in CE. The enantioseparation is carried out using polar organic mixtures of acetonitrile (ACN), methanol (MeOH), acetic acid and triethylamine as run buffer. The influences of the chiral selector concentration, ACN/MeOH ratio, applied voltage and capillary temperature on enantioseparation are investigated. The results show that AZM is a viable chiral selector in CE for the enantioseparation of the type of chiral drugs investigated.