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Suzuki N. Understanding nonlinear composition dependency of enantioselectivity in chiral separation using mixed micelle. J Colloid Interface Sci 2022; 627:578-586. [PMID: 35878457 DOI: 10.1016/j.jcis.2022.07.086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 10/17/2022]
Abstract
HYPOTHESIS Mixtures of chiral and achiral building blocks of supramolecules exhibit interesting cooperative phenomena, indicated by the nonlinear composition dependence of the chiral properties. However, the nonlinear composition dependence of the enantioselectivity of mixed micelles is not well understood. It was hypothesized that in-depth understanding can be achieved by carefully investigating the composition dependence of the properties. EXPERIMENTS In this work, the nonlinear composition dependence of the enantioselectivity was found for the mixed micelle of achiral and chiralN-acyl amino acids by micellar electrokinetic chromatography (MEKC). Capillary electrophoresis, circular dichroism (CD) spectroscopy, surface tension measurement, and fluorescence spectroscopy were used to investigate the mechanisms. FINDINGS Four mechanisms that could be causing the nonlinearity were investigated: (i) synergistic and antagonistic interactions of the surfactants; (ii) the chiral transfer from chiral to achiral surfactant; (iii) differences in the retention factor; and (iv) cooperative chiral recognition of the chiral and achiral surfactant. The investigation of the composition dependency of critical micelle concentration (CMC) and molar circular dichroism revealed that the effect of (i) and (ii) was negligibly small. The newly derived equations for (iii) and (iv) revealed that (iii) and (iv) have a major or medium effect on the nonlinear enantioselectivity.
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Affiliation(s)
- Nozomu Suzuki
- Department of Chemistry, College of Science, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan; Department of Human Studies, Faculty of Arts and Humanities, Shikoku Gakuin University, 3-2-1 Bunkyo-cho, Zentsuji, Kagawa 765-8505, Japan.
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Abstract
Microemulsion electrokinetic chromatography (MEEKC) is a special mode of capillary electrophoresis employing a microemulsion as carrier electrolyte. Analytes may partition between the aqueous phase of the microemulsion and its oil droplets which act as a pseudostationary phase. The technique is well suited for the separation of neutral species, in which case charged oil droplets (obtained by addition of an anionic or cationic surfactant) are present. A single set of separation parameters may be sufficient for separation of a wide range of analytes belonging to quite different chemical classes. Fine-tuning of resolution and analysis time may be achieved by addition of organic solvents, by changes in the nature of the surfactants (and cosurfactants) used to stabilize the microemulsion, or by various additives that may undergo some additional interactions with the analytes. Besides the separation of neutral analytes (which may be the most important application area of MEEKC), it can also be employed for cationic and/or anionic species. In this chapter, MEEKC conditions are summarized that have proven their reliability for routine analysis. Furthermore, the mechanisms encountered in MEEKC allow an efficient on-capillary preconcentration of analytes, so that the problem of poor concentration sensitivity of ultraviolet absorbance detection is circumvented.
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Affiliation(s)
- Wolfgang Buchberger
- Institut für Analytische Chemie, Universität Linz, TNF-Tower, T 209, Altenbergerstraße 69, Linz, 4040, Austria.
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Ma Y, Zhang H, Chen H, Chen X. Recent developments in chiral analysis of β-blocker drugs by capillary electromigration techniques. Electrophoresis 2014; 35:3345-54. [DOI: 10.1002/elps.201400363] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 08/23/2014] [Accepted: 08/24/2014] [Indexed: 02/06/2023]
Affiliation(s)
- Yanhua Ma
- State Key Laboratory of Applied Organic Chemistry; Lanzhou University; Lanzhou P. R. China
- Department of Chemistry; Lanzhou University; Lanzhou P. R. China
| | - Huige Zhang
- State Key Laboratory of Applied Organic Chemistry; Lanzhou University; Lanzhou P. R. China
- Department of Chemistry; Lanzhou University; Lanzhou P. R. China
| | - Hongli Chen
- State Key Laboratory of Applied Organic Chemistry; Lanzhou University; Lanzhou P. R. China
- Department of Chemistry; Lanzhou University; Lanzhou P. R. China
| | - Xingguo Chen
- State Key Laboratory of Applied Organic Chemistry; Lanzhou University; Lanzhou P. R. China
- Department of Chemistry; Lanzhou University; Lanzhou P. R. China
- Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province; Lanzhou P. R. China
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Yang H, Ding Y, Cao J, Li P. Twenty-one years of microemulsion electrokinetic chromatography (1991-2012): A powerful analytical tool. Electrophoresis 2013; 34:1273-94. [DOI: 10.1002/elps.201200494] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 12/18/2012] [Accepted: 01/22/2013] [Indexed: 12/18/2022]
Affiliation(s)
- Hua Yang
- State Key Laboratory of Natural Medicines (China Pharmaceutical University); Nanjing; P. R. China
| | - Yao Ding
- State Key Laboratory of Natural Medicines (China Pharmaceutical University); Nanjing; P. R. China
| | - Jun Cao
- College of Material Chemistry and Chemical Engineering; Hangzhou Normal University; Hangzhou; P. R. China
| | - Ping Li
- State Key Laboratory of Natural Medicines (China Pharmaceutical University); Nanjing; P. R. China
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Borst C, Holzgrabe U. Cyclodextrin-mediated enantioseparation in microemulsion electrokinetic chromatography. Methods Mol Biol 2013; 970:363-375. [PMID: 23283790 DOI: 10.1007/978-1-62703-263-6_23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Chiral separation by means of cyclodextrins has a long-standing tradition in capillary electrophoresis techniques. Here we present a chiral method utilizing the recently introduced microemulsion electrokinetic chromatography. The microemulsion consisting of 1.0% SDS, 4.0% 1-butanol, 3.0% 2-propanol, 0.5% ethylacetate, and 91.5% 20 mM phosphate buffer pH 2.5 serves as a pseudostationary phase which is complemented by sulfated cyclodextrin as a second phase. The analytes partition between the aqueous running buffer and both pseudostationary phases, the oil droplets and the cyclodextrins. Enantiomers are separated due to the formation of transient diastereomeric complexes with the cyclodextrins. For the racemates of ephedrine derivatives studied here sulfated β-cyclodextrin was successfully applied. The method is appropriate to resolve an entire series of chiral phenethylamines and can be used for separation of the racemates and impurity profiling, e.g., the determination of the enantiomeric excess.
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Affiliation(s)
- Claudia Borst
- Institute of Pharmacy and Food Chemistry, University of Würzburg, Würzburg, Germany
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6
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Abstract
Capillary electrophoresis (CE) has matured to one of the major liquid phase enantiodifferentiation techniques since the first report in 1985. This can be primarily attributed to the flexibility as well as the various modes available including electrokinetic chromatography (EKC), micellar electrokinetic chromatography (MEKC), and microemulsion electrokinetic chromatography (MEEKC). In contrast to chromatographic techniques, the chiral selector is mobile in the background electrolyte. Furthermore, a large variety of chiral selectors are available that can be easily combined in the same separation system. In addition, the migration order of the enantiomers can be adjusted by a number of approaches. In CE enantiodifferentiations the separation principle is comparable to chromatography while the principle of the movement of the analytes in the capillary is based on electrophoretic phenomena. The present chapter will focus on mechanistic aspects of CE enantioseparations including enantiomer migration order and the current understanding of selector-selectand structures. Selected examples of the basic enantioseparation modes EKC, MEKC, and MEEKC will be discussed.
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Affiliation(s)
- Gerhard K E Scriba
- Department of Pharmaceutical/Medicinal Chemistry, Friedrich Schiller University Jena, Philosophenweg 14, 07743, Jena, Germany,
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Hu SQ, Lü WJ, Ma YH, Hu Q, Dong LJ, Chen XG. Chiral separation of β-blockers by MEEKC using neutral microemulsion: Analysis of separation mechanism and further elucidation of resolution equation. Electrophoresis 2012; 34:260-8. [DOI: 10.1002/elps.201200150] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 07/26/2012] [Accepted: 08/16/2012] [Indexed: 02/01/2023]
Affiliation(s)
| | | | | | | | | | - Xing-Guo Chen
- National Key Laboratory of Applied Organic Chemistry; Lanzhou University; Lanzhou; P. R. China
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Ryan R, Altria K, McEvoy E, Donegan S, Power J. A review of developments in the methodology and application of microemulsion electrokinetic chromatography. Electrophoresis 2012; 34:159-77. [PMID: 23161220 DOI: 10.1002/elps.201200375] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 08/27/2012] [Accepted: 08/27/2012] [Indexed: 11/10/2022]
Abstract
MEEKC is a mode of CE, which utilizes microemulsion (ME) as the BGE to achieve separation of a diverse range of analytes. MEs are composed of nanometer-sized oil droplets suspended in aqueous buffer which are stabilized by the presence of a surfactant and co-surfactant. These MEs are commonly referred to as oil-in-water MEs and their application in MEEKC has been extensively examined. This review details advances in the theory, methodology, and application of MEEKC during the period 2010-2012. Areas covered include online sample concentration, advances in chiral separations, use of coated capillaries, chemometric approaches, and the use of novel additives to the ME system. This review also provides the reader with an introduction to MEEKC and a presentation of recent applications.
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Affiliation(s)
- Richie Ryan
- Waterford Institute of Technology, Waterford, Ireland.
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Yu L, Chu K, Ye H, Liu X, Yu L, Xu X, Chen G. Recent advances in microemulsion electrokinetic chromatography. Trends Analyt Chem 2012. [DOI: 10.1016/j.trac.2011.11.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Aturki Z, D'Orazio G, Rocco A, Fanali S. Advances in the enantioseparation of β-blocker drugs by capillary electromigration techniques. Electrophoresis 2011; 32:2602-28. [PMID: 21905049 DOI: 10.1002/elps.201100153] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 04/08/2011] [Accepted: 04/09/2011] [Indexed: 11/07/2022]
Abstract
β-Blocker drugs or β-adrenergic blocking agents are an important class of drugs, prescribed with great frequency. They are used for various diseases, particularly for the treatment of cardiac arrhythmias, cardioprotection after myocardial infarction (heart attack), and hypertension. Almost all β-blocker drugs possess one or more stereogenic centers; however; only some of them are administered as single enantiomers. Since both enantiomers can differ in their pharmacological and toxicological properties, enantioselective analytical methods are required not only for pharmacodynamic and pharmacokinetic studies but also for quality control of pharmaceutical preparations with the determination of enantiomeric purity. In addition to the chromatographic tools, in recent years, capillary electromigration techniques (CE, CEC, and MEKC) have been widely used for enantioselective purposes employing a variety of chiral selectors, e.g. CDs, polysaccharides, macrocyclic antibiotics, proteins, chiral ion-paring agents, etc. The high separation efficiency, rapid analysi,s and low consumption of reagents of electromigration methods make them a very attractive alternative to the conventional chromatographic methods. In this review, the development and applications of electrodriven methods for the enantioseparation of β-blocker drugs are reported. The papers concerning this topic, published from January 2000 until December 2010, are summarised here. Particular attention is given to the coupling of chiral CE and CEC methods to MS, as this detector provides high sensitivity and selectivity.
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Affiliation(s)
- Zeineb Aturki
- Istituto di Metodologie Chimiche, Consiglio Nazionale delle Ricerche, Area della Ricerca di Roma, Monterotondo Scalo, Rome, Italy
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Lu H, Chen G. Recent advances of enantioseparations in capillary electrophoresis and capillary electrochromatography. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2011; 3:488-508. [PMID: 32938063 DOI: 10.1039/c0ay00489h] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A comprehensive survey of recent developments and applications of capillary electromigration techniques for enantioseparations from January 2006 to June 2010 is presented. The techniques include capillary electrophoresis, chip capillary electrophoresis and capillary electrochromatography. The separation principles and the chiral recognition mechanisms are discussed. Additionally, on-line preconcentrations in chiral capillary electrophoresis are also reviewed.
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Affiliation(s)
- Huang Lu
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou, Fujian 350002, China.
- Department of Chemistry and Chemical Engineering, Minjiang University, Fuzhou, Fujian 350108, China
| | - Guonan Chen
- Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou, Fujian 350002, China.
- Department of Chemistry and Chemical Engineering, Minjiang University, Fuzhou, Fujian 350108, China
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12
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Comparison of chiral electrophoretic separation methods for phenethylamines and application on impurity analysis. J Pharm Biomed Anal 2010; 53:1201-9. [DOI: 10.1016/j.jpba.2010.06.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 11/20/2022]
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Ryan R, McEvoy E, Sheila Donegan, Power J, Altria K. Recent developments in the methodology and application of MEEKC. Electrophoresis 2010; 32:184-201. [DOI: 10.1002/elps.201000372] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/28/2010] [Accepted: 09/21/2010] [Indexed: 02/05/2023]
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Hu SQ, Chen YL, Zhu HD, Shi HJ, Yan N, Chen XG. Effect of molecular structure of tartrates on chiral recognition of tartrate–boric acid complex chiral selectors in chiral microemulsion electrokinetic chromatography. J Chromatogr A 2010; 1217:5529-35. [DOI: 10.1016/j.chroma.2010.06.063] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 06/18/2010] [Accepted: 06/24/2010] [Indexed: 11/26/2022]
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Ryan R, Donegan S, Power J, Altria K. Advances in the theory and application of MEEKC. Electrophoresis 2010; 31:755-67. [DOI: 10.1002/elps.200900568] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hu S, Chen Y, Zhu H, Zhu J, Yan N, Chen X. In situ synthesis of di-n-butyl l-tartrate–boric acid complex chiral selector and its application in chiral microemulsion electrokinetic chromatography. J Chromatogr A 2009; 1216:7932-40. [DOI: 10.1016/j.chroma.2009.09.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 09/11/2009] [Accepted: 09/15/2009] [Indexed: 11/30/2022]
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Ryan R, Donegan S, Power J, McEvoy E, Altria K. Recent advances in the methodology, optimisation and application of MEEKC. Electrophoresis 2009; 30:65-82. [PMID: 19107700 DOI: 10.1002/elps.200800439] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
MEEKC is an electrodriven separation technique. Oil-in-water microemulsions (MEs) and to a lesser extent water-in-oil MEs have been used in MEEKC as BGEs to achieve separation of a diverse range of solutes. The more common (oil-in-water) MEs are composed of nanometre-sized droplets of oil suspended in an aqueous buffer. Interfacial tension between the oil and aqueous phase is reduced close to zero by the presence of a surfactant and a co-surfactant. MEEKC is capable of providing fast and efficient separations for a wide range of acidic, basic and neutral, water-soluble and -insoluble compounds. This review details the advances in MEEKC-based separations from the period 2006 to 2008. Areas covered include online sample concentration, chiral separation, suppressed electroosmosis MEEKC, MEEKC-MS, and the use of MEEKC in predicting migration behaviour and solute characteristics. A fundamental introduction to MEEKC, along with the presentation and discussion of recent applications is also included.
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Affiliation(s)
- Richie Ryan
- Waterford Institute of Technology, Cork Road Campus, Waterford, Ireland.
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Kojtari AB, Guetschow ED, Foley JP. The effect of co-surfactant-modified micelles on chiral separations in EKC. Electrophoresis 2009; 30:2829-36. [DOI: 10.1002/elps.200800828] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kojtari AB, Foley JP. Effect of microemulsion component purity on the chromatographic figures of merit in chiral microemulsion electrokinetic chromatography. J Chromatogr A 2009; 1216:3488-91. [DOI: 10.1016/j.chroma.2008.10.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Revised: 10/06/2008] [Accepted: 10/07/2008] [Indexed: 10/21/2022]
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Preinerstorfer B, Lämmerhofer M, Lindner W. Advances in enantioselective separations using electromigration capillary techniques. Electrophoresis 2009; 30:100-32. [DOI: 10.1002/elps.200800607] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Enantioseparation of esbiothrin by cyclodextrin-modified microemulsion and micellar electrokinetic chromatography. J Sep Sci 2008; 31:3911-20. [DOI: 10.1002/jssc.200800378] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Affiliation(s)
- Timothy J Ward
- Millsaps College 1701 North State Street, Box 150306, Jackson, Mississippi 39210, USA.
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