Separation of cationic analytes by nonionic micellar electrokinetic chromatography using polyoxyethylene lauryl ether surfactants with different polyoxyethylene length

Although nonionic micellar electrokinetic chromatography is used for the separation of charged compounds that are not easily separated by capillary zone electrophoresis, the effect of the hydrophilic moiety of the nonionic surfactant has not been studied well. In this study, the separation of ultraviolet‐absorbing amino acids was studied in electrokinetic chromatography using neutral polyoxyethylene lauryl ether surfactants (Adekatol) in the separation solution. The effect of the polyethylene moiety (the number of repeating units was from 6.5 to 50) of the hydrophobic test amino acids (methionine, tryptophan, and tysorine) was studied using a 10 cm effective length capillary. The separation mechanism was based on hydrophobic as well as hydrogen bonding interactions at the micellar surface, which was made of the polyoxyethylene moiety. The length of the polyoxyethylene moiety of the surfactants was not important in nonionic micellar electrokinetic chromatography mode.     

微量金属元素的毛细管电泳分析方法及应用

综述了毛细管电泳分析微量金属元素的基本原理、分离模式(CZE、MKEC、非水电泳、芯片分离等)、检测方法(紫外、荧光、化学发光、安培、电导、质谱联用技术)等的进展和该技术在环境、生物医学领域的研究与应用。引用文献94篇。     

Separation of binaphthyl enantiomers by capillary zone electrophoresis and electrokinetic chromatography

The capillary electrophoretic (CE) separation of the enantiomers of three binaphthyl compounds is investigated. Several CE modes such as cyclodextrin (CD) modified capillary zone electrophoresis (CZE) (CD-CZE), micellar electrokinetic chromatography (MEKC), cyclodextrin electrokinetic chromatography (CD-EKC), etc. are employed for the simultaneous enantiomer separation of the three solutes. The successful separation was achieved by combining two modes, in other words by using more than two chiral selectors. A development of the CE enantiomer separation is demonstrated for the binaphthyl compounds. The enantioselectivity of binaphthyl compounds is alo briefly discussed.     

New possibilities of micellar electrokinetic chromatography and microemulsion electrokinetic chromatography in the determination of catechols and catecholamines in natural samples

New possibilities were revealed and evaluative characteristics were obtained for different versions of capillary electrophoresis with UV detection, namely, micellar electrokinetic chromatography with normal and reversed polarity and microemulsion electrokinetic chromatography, used for determining catechols and catecholamines in green and black tea and in urine.     

在线富集二维毛细管电泳分析新体系检测尿样中药物及对映体

将在线富集技术同二维(2D)毛细管电泳(CE)分离相结合同时提高复杂样品中痕量组分的分离度和检测灵敏度.毛细管区带电泳(CZE)作为第一维,分析物根据淌度不同进行分离,第一维流出组分进入第二维毛细管,根据分配系数不同进行胶束电动毛细管色谱(MEKC)分离.采用阳离子选择性耗尽进样(CSEI)在柱预富集,延长进样时间,增大进样量;同时在二维毛细管接口处采用动态pH联接/胶束扫集在线富集技术不仅避免第一维分离组分在接口处扩散,还可进一步压缩样品区带.同常规电动进样CE分离相比,该在线富集二维分离技术的分离能力远远高于一维CZE或MEKC分离,富集倍数达到(0.5～1.2)×104.该法成功应用于人体尿样中四种药物及对映体的分析测定,浓度检出限为0.1～0.3μg/L.进一步研究了人体尿样中四种药物24h内的药代动力学规律.     

Fenofibrate and fenofibric acid analysis by capillary electrophoresis

A capillary electrophoresis method has been developed to measure fenofibrate in capsules based on micellar electrokinetic capillary chromatography with detection at 280 nm using a borate buffer containing sodium dodecyl sulfate (SDS). However, the metabolite of this drug (fenofibric acid) in serum and whole blood was analyzed by capillary zone electrophoresis (CZE) in a borate-carbonate buffer using acetonitrile stacking. The analysis is rapid, < 7 min with no interferences. Incubation of fenofibrate in whole blood caused hydrolysis of the ester bond with the release of fenofibric acid.     

The multi-concentration and two-dimensional capillary electrophoresis method for the analysis of drugs in urine samples

A novel method has been developed by integration of multi-concentration and two-dimensional(2D) capillary electrophoresis(CE) for simultaneous enhancement of detection sensitivity and separation power in complex samples.Capillary zone electrophoresis(CZE) was used as the first dimension separation according to mobilities,from which the effluent fractions were further analyzed by micellar electrokinetic capillary chromatography(MEKC) acting as the second dimension.Cation-selective exhaustive injection(CSEI) ...     

Analysis of differential detergent fractions of an AtT-20 cellular homogenate using one- and two-dimensional capillary electrophoresis

Differential detergent fractionation was used to sequentially extract cytosolic, membrane, nuclear, and cytoskeletal fractions from AtT-20 cells. Extracted components were denatured by sodium dodecyl sulfate (SDS) and then labeled with the fluorogenic reagent 3-(2-furoyl) quinoline-1-carboxaldehyde. Both capillary sieving electrophoresis (CSE) and micellar electrokinetic capillary chromatography (MECC) were used to separate labeled components by one-dimensional (1D) electrophoresis. Labeled components were also separated by two-dimensional (2D) capillary electrophoresis; CSE was employed in the first dimension and MECC in the second dimension. Roughly 150 fractions were transferred from the first to the second capillary for this comprehensive analysis in 2.5 h.     

Development of a capillary electrophoretic method for the separation of diastereoisomers of a new human immunodeficiency virus protease inhibitor

A capillary electrophoretic (CE) method was developed for the separation of diastereoisomers of a new human immunodeficiency virus (HIV) protease inhibitor TMC114. In total 16 isomers of this drug have been synthesized (eight pairs of enantiomers). We succeeded in the separation of the eight diastereoisomers, but no enantiomers could be separated. Because of the high similarity and water-insolubility of these isomers, the separation is a real challenge. Different CE modes were tried out: capillary zone electrophoresis (CZE), nonaqueous capillary electrophoresis (NACE), micellar electrokinetic capillary chromatography (MEKC), and microemulsion electrokinetic capillary chromatography (MEEKC). Only MEEKC offered resolution of these compounds.     

Determination of 20-hydroxyecdysone content by thin-layer chromatography and micellar electrokinetic chromatography

Summary Seasonal dependence of 20-hydroxyecdysone content ofSerratula tinctoria andSerratula wolffii (Asteraceae) was investigated by micellar electrokinetic chromatography (MEKC). Samples were collected each month through the vegetation period. The leaves were dried, milled and extracted with methanol. Clean-up of the extracts was by solid-phase extraction using a polyamide micro-column to remove flavonoids and other plant phenolics which can interfere with the analysis. This work deals with the separation of 20-hydroxyecdysone from polypodine B and the seasonal variation of 20-hydroxyecdysone concentration. Determinations have been performed by both thin-layer chromatography and capillary electrophoresis using micellar electrokinetic chromatography. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997.     

毛细管电泳在手性分离中的应用进展

本文以手性选择剂为线索综述了近五年来毛细管区带电泳和胶束电动毛细管电色谱在手性药物拆分中的应用进展,列举了部分手性药物拆分实例.     

Separation of chlorins and carotenoids in capillary electrophoresis

The present study reports the investigation of capillary electrophoresis (CE) for the separation of the photosynthetic pigments (chlorophyll derivatives as well as carotenoids) together. Various CE methods, such as micellar electrokinetic chromatography, capillary electrokinetic chromatography, and nonaqueous capillary electrophoresis (NACE) are tested, with coated and uncoated capillary columns to evaluate optimal separation conditions using diode array detection. The effect of different type and composition of organic solvents and surfactants on the separation is discussed. Detection limits are found in the range of 1.14-2.45 ppm. According to the system suitability results, the most effective separation is observed using NACE with Aliquat 336 as cationic surfactant in coated capillary and mixture of MeOH-ACN-THF (5:4:1, v/v/v) as solvent. Quantitative evolution is investigated, and recovery percentage values are found to be 96.7-102%.     

Determination of impurities and counterions of pharmaceuticals by capillary electromigration methods

The review presents a survey of recent applications of high‐performance capillary electromigration methods—capillary zone electrophoresis, nonaqueous capillary electrophoresis, capillary isotachophoresis, micellar electrokinetic chromatography, microemulsion electrokinetic chromatography and capillary electrochromatography—for the determination of impurities of pharmaceuticals, including chiral impurities, for the period 2007–2013. In addition, due to the missing evaluation of the determination of counterions of pharmaceuticals by capillary electromigration methods in the last 20 years, the publications dealing with this topic since 1995 are included in this review. General aspects of both these types of applications of capillary electromigration methods in pharmaceutical analysis are discussed, and detailed experimental conditions used for determination of various chemical impurities and counterions of many particular drugs are described.     

Chromatographic and electrophoretic methods for determining polyphenol compounds

The main physicochemical methods for identifying and quantifying polyphenol compounds in various plant and food objects (tea, wine) and human biological fluids (urine, plasma, blood serum, saliva) were reviewed, such as chromatography (high-performance liquid chromatography and thin-layer chromatography) and electrophoresis (capillary zone electrophoresis and micellar electrokinetic chromatography). Different procedures for sample preparation were discussed, including liquid, solid-phase, supercritical fluid extraction, and high-pressure liquid extraction.     

不同缓冲体系对毛细管电泳法分离15种核苷类化合物效果的比较

对毛细管电泳法分离15种核苷类化合物所用的不同缓冲液体系进行了系统比较,确定不同模式毛细管电泳法分析多种核苷类化合物的最适合背景缓冲液体系(BGE)。分别以四硼酸钠、磷酸氢二钠、乙酸钠、碳酸氢钠、乙酸铵和乙二胺(DEA)为背景电解质,对毛细管区带电泳(CZE)、毛细管电泳-电喷雾飞行时间质谱(CE-ESI-TOF/MS)以及胶束电动毛细管电泳(MEKC)3种模式进行比较,并对其中几种优势缓冲体系进行了优化。结果表明,CZE模式下使用四硼酸钠和磷酸氢二钠缓冲体系无法同时分离15种核苷类化合物,因此只适用于分析核苷类化合物数量较少的样品。而使用含有2%丙酮的300 mmol/L DEA能完全分开15种核苷类化合物,且分辨率和峰形良好。MEKC模式下,以25 mmol/L磷酸氢二钠(添加70 mmol/L十二烷基磺酸钠(SDS))为缓冲盐的分离结果最佳,并且此方法能成功应用于海洋生物海葵中核苷类化合物的分离。CE-ESI-TOF/MS分析中,以20 mmol/L乙酸铵(pH 10.0)为背景电解质,正离子模式检测,15种核苷类化合物的质谱信号均良好,检测灵敏度明显优于文献中报道的使用DEA缓冲体系的结果。本研究阐明了不同缓冲体系对15种核苷类化合物分离的适用性,为毛细管电泳技术在复杂基质中多种核苷类化合物的分离方法中的应用奠定了基础。     

Free solution capillary electrophoresis and micellar electrokinetic resolution of amino acid enantiomers and peptide isomers with L- and D-Marfey's reagents

Separation of amino acid enantiomers and peptide isomers has been made possible through the use of Marfey's reagent and high-performance capillary electrophoresis (HPCE). Samples of amino acids and peptides were first derivatized with Marfey's reagent and subsequently analyzed by HPCE. Different modes of separation were investigated including free solution and micellar electrokinetic chromatography. The use of micellar electrokinetic chromatography in combination with L- and D-Marfey's reagent offered unequivocal means to confirm the presence of D-amino acid in an unknown sample. This method is also particularly useful for the analysis of peptide isomers.     

微流控芯片二维电泳研究进展

综述了微流控芯片二维电泳技术及其在生命科学中的应用,包括胶束电动力学毛细管色谱(MEKC)与毛细管区带电泳(CZE)、等电聚焦(IEF)与CZE、开管电色谱(OCEC)与CZE耦联等模式的二维微流控芯片。展望了二维微流控芯片的应用前景。     

Determination of Low-Molecular-Mass Phenolic and Non-Phenolic Lignin Degradation Compounds in Wood Digestion Solutions by Capillary Electrophoresis

 Different capillary electrophoretic techniques were investigated and compared for the separation of low-molecular-mass phenolic and neutral lignin degradation compounds. Simple capillary zone electrophoresis (CZE) was not suited for this problem. Switching to micellar electrokinetic capillary chromatography (MEKC) by adding micelle-forming reagents to the carrier electrolyte enhanced the separation performance considerably. Alternatively, microemulsion electrokinetic chromatography (MEEKC) was investigated. This is a CE technique in which analytes interact with moving oil droplets present in a microemulsion buffer. Using the optimized carrier electrolyte systems and a 60 cm×50 μm I.D. bubble cell capillary it was possible to analyse solutions of different wood digestion procedures and to investigate differences in lignin degradation products during use of different kinds of wood (eucalyptus, beech, scotch pine and acacia). Received August 25, 1999. Revision April 13, 2000     

Study of the Electrophoretic Behaviour of Flavonoids

The electrophoretic behaviour of 13 flavonoids commonly found in medicinal plants has been studied. The performance of two modes of separation, capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC), was assessed and compared. MEKC was found to be more effective for separation of the analytes. The effect of structure on the electrophoretic behaviour of the flavonoids is also discussed.     

Pharmaceutical applications of micelles in chromatography and electrophoresis

This review surveys the use of micelles as separation media in chromatography and electrophoresis. Applications to pharmaceuticals whose molecular masses are relatively small are focused on in this review. In high-performance liquid chromatography (HPLC), chromatography using micelles and reversed-phase stationary phases such as octadecylsilylized silica gel (ODS) columns is known as micellar liquid chromatography (MLC). The main application of MLC to pharmaceutical analysis is the same as in ion-pair chromatography using alkylsulfonate or tetraalkylammonium. In most cases, selectivity is much improved compared with other short alkyl chain ion-pairing agents such as pentanesulfonate or octanesulfonate. Direct plasma/serum injection can be successful in MLC. Separation of small ions is also successful by using gel filtration columns and micellar solutions. In electrophoresis, especially capillary electrophoresis (CE), micelles are used as pseudo-stationary phases in capillary zone electrophoresis (CZE). This mode is called micellar electrokinetic chromatography (MEKC). Most of the drug analysis can be performed by using the MEKC mode because of its wide applicability. Enantiomer separation, separation of amino acids and closely related peptides, separation of very complex mixtures, determination of drugs in biological samples etc. as well as separation of electrically neutral drugs can be successfully achieved by MEKC. Microemulsion electrokinetic chromatography (MEEKC), in which surfactants are also used in forming the microemulsion, is successful for the separation of electrically neutral drugs as in MEKC. This review mainly describes the typical applications of MLC and MEKC for the analysis of pharmaceuticals.