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Fuxová H, Labíková M, Ivanovská A, Eliášová P, Kubů M, Hovorka Š, Přibyl M, Čížek J, Bartůněk V, Kohout M, Izák P. Zeolite-based chiral ion-exchangers for chromatographic enantioseparations and potential applications in membrane separation processes. Talanta 2024; 278:126419. [PMID: 38908136 DOI: 10.1016/j.talanta.2024.126419] [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: 11/29/2023] [Revised: 04/30/2024] [Accepted: 06/10/2024] [Indexed: 06/24/2024]
Abstract
Chiral resolution of racemic compounds represents an important task in research and development and, most importantly, in the large-scale production of pharmaceuticals. Zeolites, which are already frequently utilized for their unique properties, represent materials that can be used for the development of new chiral stationary phases for liquid chromatography, simulated moving bed or enantioselective membranes. The aim of this study was to modify a series of MWW zeolites by a chiral anion-exchange type selector thereby creating a chiral stationary phase for enantiomeric resolution of acidic compounds. To evaluate the applicability of the prepared chiral stationary phase in liquid chromatography, we used N-protected amino acids as model analytes. First, we tested the new sorbents preferential sorption using N-(3,5-dinitrobenzoyl)leucine. We observed outstanding sorption properties of a zeolite-based sorbent (MCM-36), which were comparable to spherical chromatographic silica. This particular material was subsequently packed into a chromatographic column, which was tested under polar organic mode HPLC conditions facilitating baseline resolution of 5 out of 8 N-protected amino acids. Although the chromatographic performance shows several drawbacks (high backpressure, low column efficiency), it clearly documents the potential of the novel materials in chiral separation. To the best of our knowledge, this is the first example of the preparation of the chiral stationary phase based on MWW zeolites ever.
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Affiliation(s)
- Hana Fuxová
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Magdaléna Labíková
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Anna Ivanovská
- Faculty of Technology and Metallurgy, University of SS. Cyril and Methodius, Skopje, Macedonia
| | - Pavla Eliášová
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43 Prague, Czech Republic
| | - Martin Kubů
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 2030/8, 128 43 Prague, Czech Republic
| | - Štěpán Hovorka
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Michal Přibyl
- Department of Chemical Engineering, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Jan Čížek
- Department of Chemical Engineering, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic; Institute of Chemical Process Fundamentals of the CAS, Rozvojová 135, 165 00, Prague 6, Czech Republic
| | - Vilém Bartůněk
- Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Michal Kohout
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic.
| | - Pavel Izák
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague 6, Czech Republic; Institute of Chemical Process Fundamentals of the CAS, Rozvojová 135, 165 00, Prague 6, Czech Republic.
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Asnin LD, Ziganshina DI, Klimova YA, Reshetova EN, Tůma J, Kohout M. Chiral zwitterionic stationary phases based on Cinchona alkaloids and dipeptides: Application in chiral separation of dipeptides under reversed phase conditions. J Chromatogr A 2024; 1726:464966. [PMID: 38735116 DOI: 10.1016/j.chroma.2024.464966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Revised: 04/26/2024] [Accepted: 05/02/2024] [Indexed: 05/14/2024]
Abstract
Chromatographic behavior of novel chiral stationary phases with bonded selectors based on Cinchona alkaloids modified with dipeptides was studied using dipeptides as probe molecules. Buffer-free and salt containing hydro-organic solutions were used as the mobile phases. The selectors exhibit pseudoenantiomeric behavior with respect to the L/D or LL/DD enantiomers and do not behave so with respect to the LD/DL enantiomers. The alkaloid part of the selectors is the driver of enantioselectivity, while the dipeptide substituent plays a modulating role. The quinidine-based selectors demonstrate stronger adsorption affinity and higher enantioselectivity as compared to the quinine-based selectors. The dipeptide analytes containing a glycyl fragment are weaker retained and their enantiomers are worse separated comparing to dipeptides with both units being larger amino acids. Moreover, a phenyl group in the structure of a dipeptide analyte facilitates enantioseparation. The effect of the mobile phase composition on retention depends on the hydrophobicity of an analyte. Hydrophobic dipeptides are better eluted by methanol-rich solvents, hydrophilic dipeptides are better eluted with water-rich solvents, and dipeptides with an intermediate hydrophobicity demonstrate a U-shaped or more complicated dependence of the retention factor on the percentage of methanol. Even a small buffer addition to the mobile phase decreases retention, but the ion-exchange mechanism was not confirmed. The effect of an electrolyte is rather due to the shielding of the charged groups of the selector reducing thereby electrostatic interaction between the selector and analyte. Efficiency of the novel columns is comparable to that of other brush-type chiral columns, the highest achieved number of the theoretical plates per 1 m varying between 30,000 and 40,000.
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Affiliation(s)
- Leonid D Asnin
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, 29 Komsomolsky Al., Perm 614990, Russia
| | - Daria I Ziganshina
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, 29 Komsomolsky Al., Perm 614990, Russia
| | - Yana A Klimova
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, 29 Komsomolsky Al., Perm 614990, Russia
| | - Elena N Reshetova
- Institute of Technical Chemistry of the Ural Branch of the Russian Academy of Sciences, 3 Academician Korolev Str., Perm 614013, Russia
| | - Jiří Tůma
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Michal Kohout
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic.
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Kuncová A, Svoboda J, Tůma J, Asnin L, Schug K, Kohout M. Chiral zwitterionic stationary phases based on Cinchona alkaloids and dipeptides - design, synthesis and application in chiral separation. J Chromatogr A 2024; 1717:464664. [PMID: 38271770 DOI: 10.1016/j.chroma.2024.464664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/29/2023] [Accepted: 01/17/2024] [Indexed: 01/27/2024]
Abstract
Chiral resolution of polar organic compounds such as amino acids and peptides represents an important chromatographic task due to increasing significance of natural species, which play important signaling and regulatory roles in the living organisms. Despite the number of available chiral stationary phases, this task remains challenging, since not many of the commercially available systems are capable to resolve non-derivatized zwitterionic species. In this study, we present a target-oriented design of a new class of chiral selectors. Pursuing the goal to separate amino acids, and especially short peptides, we have combined Cinchona alkaloids - quinine and quinidine - with three different biogenic dipeptides. We have synthesized six different chiral stationary phases, with selector loading of ∼200 μmol g-1, and tested their chiral recognition capabilities for acidic, basic and zwitterionic analytes using various mobile phases. We have observed that all chiral stationary phases retain the chiral anion exchange capability known for commercially available Cinchona-based columns leading to baseline or partial resolution of six out of ten analytes. The performance in chiral resolution of basic analytes is not optimum due to the weak cation exchange character of the peptidic residue. However, we report on encouraging results in the chiral resolution of short peptides, for which, depending on their structure, we see the chiral resolution of up to three stereoisomers (from four possible) in a preliminary screening.
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Affiliation(s)
- Anežka Kuncová
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Jiří Svoboda
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Jiří Tůma
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Leonid Asnin
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, 29 Komsomolsky Al, 614990 Perm, Russia
| | - Kevin Schug
- Department of Chemistry and Biochemistry, College of Sciences, UT Arlington, 700 Planetarium PI, TX 760 19, Arlington, United States
| | - Michal Kohout
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic.
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Enantiomeric separation of newly synthesized amino, thio, and oxy derivatives of monoterpene lactones, amides, and ester applying polysaccharide-based chiral stationary phases in normal-phase mode. J Chromatogr A 2022; 1672:463050. [DOI: 10.1016/j.chroma.2022.463050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 11/18/2022]
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Asnin L, Herciková J, Lindner W, Klimova Y, Ziganshina D, Reshetova E, Kohout M. Chiral separation of dipeptides on Cinchona-based zwitterionic chiral stationary phases under buffer-free reversed-phase conditions. Chirality 2022; 34:1065-1077. [PMID: 35596543 DOI: 10.1002/chir.23471] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 11/11/2022]
Abstract
Chiral zwitterion ion exchangers represent efficient chiral stationary phases for stereoselective resolution of various analytes including chiral acids, bases, and zwitterions. In this contribution, we have focused on utilization of chiral zwitterionic sorbents, denoted as ZWIX (+A) and ZWIX (-A). These are analogical chiral systems to commercially available columns, Chiralpak ZWIX (+) and Chiralpak ZWIX (-), which are usually operated with buffered mobile phases. In this contribution, we have studied the enantiorecognition power of the ZWIX (+A) and ZWIX (-A) columns on a series of dipeptides operated under buffer-free reversed-phase conditions. Retention characteristics of zwitterionic dipeptides are discussed using an electrostatically driven adsorption model, which provides a good fit with both monotonous and U-shaped curves.
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Affiliation(s)
- Leonid Asnin
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, Perm, Russia
| | - Jana Herciková
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Prague, Czech Republic
| | - Wolfgang Lindner
- Institute of Analytical Chemistry, University of Vienna, Vienna, Austria
| | - Yana Klimova
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, Perm, Russia
| | - Daria Ziganshina
- Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, Perm, Russia
| | - Elena Reshetova
- Institute of Technical Chemistry of the Ural Branch of the Russian Academy of Sciences, Perm, Russia
| | - Michal Kohout
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Prague, Czech Republic
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Zhang JH, Xie SM, Yuan LM. Recent progress in the development of chiral stationary phases for high-performance liquid chromatography. J Sep Sci 2021; 45:51-77. [PMID: 34729907 DOI: 10.1002/jssc.202100593] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 12/20/2022]
Abstract
Separations and analyses of chiral compounds are important in many fields, including pharmaceutical production, preparation of chemical intermediates, and biochemistry. High-performance liquid chromatography using a chiral stationary phase is regarded as one of the most valuable methods for enantiomeric separation and analysis because it is highly efficient, is broadly applicable, and has powerful separation capability. The focus for development of this method is the identification of novel chiral stationary phases with superior recognition performance and good stability. The present article reviews recent progress in the development of new chiral stationary phases for high-performance liquid chromatography between January 2018 and June 2021. These newly reported chiral stationary phases are divided into three categories: small organic molecule-based (cyclodextrin and its derivatives, macrocyclic antibiotics, cinchona alkaloids, and other low molecular weight chiral molecules), macromolecule-based (cellulose and amylose derivatives, chitin and chitosan derivatives, and synthetic helical polymers) and chiral porous material-based (chiral metal-organic frameworks, chiral covalent organic frameworks, and chiral inorganic mesoporous silicas). Each type of chiral stationary phase is discussed in detail.
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Affiliation(s)
- Jun-Hui Zhang
- Department of Chemistry, Yunnan Normal University, Kunming, P. R. China
| | - Sheng-Ming Xie
- Department of Chemistry, Yunnan Normal University, Kunming, P. R. China
| | - Li-Ming Yuan
- Department of Chemistry, Yunnan Normal University, Kunming, P. R. China
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Analysis of free amino acids with unified chromatography-mass spectrometry—application to food supplements. J Chromatogr A 2020; 1616:460772. [DOI: 10.1016/j.chroma.2019.460772] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/23/2019] [Accepted: 12/04/2019] [Indexed: 02/07/2023]
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Yu RB, Quirino JP. Chiral liquid chromatography and capillary electrochromatography: Trends from 2017 to 2018. Trends Analyt Chem 2019. [DOI: 10.1016/j.trac.2019.07.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Mimini V, Ianni F, Marini F, Hettegger H, Sardella R, Lindner W. Electrostatic attraction-repulsion model with Cinchona alkaloid-based zwitterionic chiral stationary phases exemplified for zwitterionic analytes. Anal Chim Acta 2019; 1078:212-220. [PMID: 31358221 DOI: 10.1016/j.aca.2019.06.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/30/2019] [Accepted: 06/02/2019] [Indexed: 12/12/2022]
Abstract
In the present paper, we demonstrated that Cinchona alkaloid cyclohexyl sulfonic acid-based zwitterionic chiral selectors (SOs) and the respective chiral stationary phases (CSPs) can be successfully employed for the enantioseparation of underivatized thus zwitterionic amino acids (the selectands, SAs) even in the absence of ionic additives in the eluent, generally used as displacer counter-ions in ion exchange chromatography. Therefore, we provided evidence that cooperative "intramolecular and intermolecular counter-ion effects" of the zwitterionic SO moiety and the zwitterionic SAs can be sufficient to modulate alone the retention characteristics without a loss of stereoselectivity. Four fully constrained β-amino acids were used as target compounds for this study. The analyses were carried out with either neat methanol, acetonitrile, water or their binary hydro-organic mixtures. A U-shaped retention profile was observed both with methanol- and acetonitrile-based eluents. Except a few cases, enantioselectivity experienced a remarkable amelioration at the "balanced region" of a buffer free hydroorganic mobile phase composition. At "the bottom" of the U-shaped curve, high α- and resolution values could be reached with most of the screened mobile phases. An electrostatically driven "attraction-repulsion model" was postulated to explain the very favourable characteristic of the two studied zwitterion-type CSPs for the retention and enantiomer separation of zwitterionic analytes.
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Affiliation(s)
- Vebi Mimini
- University of Vienna, Department of Analytical Chemistry, Währingerstrasse 38, 1090, Vienna, Austria; University of Natural Resources and Life Sciences Vienna (BOKU), Department of Chemistry, Institute for Chemistry of Renewable Resources, Konrad-Lorenz-Straße 24, A-3430, Tulln, Austria
| | - Federica Ianni
- University of Perugia, Department of Pharmaceutical Sciences, Via Fabretti 48, 06123, Perugia, Italy
| | - Francesca Marini
- University of Perugia, Department of Pharmaceutical Sciences, Via Fabretti 48, 06123, Perugia, Italy
| | - Hubert Hettegger
- University of Natural Resources and Life Sciences Vienna (BOKU), Department of Chemistry, Institute for Chemistry of Renewable Resources, Konrad-Lorenz-Straße 24, A-3430, Tulln, Austria
| | - Roccaldo Sardella
- University of Perugia, Department of Pharmaceutical Sciences, Via Fabretti 48, 06123, Perugia, Italy.
| | - Wolfgang Lindner
- University of Vienna, Department of Analytical Chemistry, Währingerstrasse 38, 1090, Vienna, Austria.
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Teixeira J, Tiritan ME, Pinto MMM, Fernandes C. Chiral Stationary Phases for Liquid Chromatography: Recent Developments. Molecules 2019; 24:E865. [PMID: 30823495 PMCID: PMC6429359 DOI: 10.3390/molecules24050865] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/17/2019] [Accepted: 02/26/2019] [Indexed: 12/13/2022] Open
Abstract
The planning and development of new chiral stationary phases (CSPs) for liquid chromatography (LC) are considered as continuous and evolutionary issues since the introduction of the first CSP in 1938. The main objectives of the development strategies were to attempt the improvement of the chromatographic enantioresolution performance of the CSPs as well as enlarge their versatility and range of applications. Additionally, the transition to ultra-high-performance LC were underscored. The most recent strategies have comprised the introduction of new chiral selectors, the use of new materials as chromatographic supports or the reduction of its particle size, and the application of different synthetic approaches for preparation of CSPs. This review gathered the most recent developments associated to the different types of CSPs providing an overview of the relevant advances that are arising on LC.
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Affiliation(s)
- Joana Teixeira
- Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
| | - Maria Elizabeth Tiritan
- Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Edifício do Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4050-208 Matosinhos, Portugal.
- Cooperativa de Ensino Superior, Politécnico e Universitário (CESPU), Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde (IINFACTS), Rua Central de Gandra, 1317, 4585-116 Gandra PRD, Portugal.
| | - Madalena M M Pinto
- Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Edifício do Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4050-208 Matosinhos, Portugal.
| | - Carla Fernandes
- Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Edifício do Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4050-208 Matosinhos, Portugal.
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Ilisz I, Bajtai A, Péter A, Lindner W. Cinchona Alkaloid-Based Zwitterionic Chiral Stationary Phases Applied for Liquid Chromatographic Enantiomer Separations: An Overview. Methods Mol Biol 2019; 1985:251-277. [PMID: 31069739 DOI: 10.1007/978-1-4939-9438-0_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
For the early 2000s, chromatographic methods applying chiral stationary phases (CSPs) became the most effective techniques for the resolution of chiral compounds on both analytical and preparative scales. High-performance liquid chromatography (HPLC) employing various types of chiral selectors covalently bonded to silica-based supports offers a state-of-the-art methodology for "chiral analysis." Although a large number of CSPs are available nowadays, the design and development of new "chiral columns" are still needed since it is obvious that in practice one needs a good portfolio of different columns to face the challenging task of enantiomeric resolutions. The development of the unique chiral anion, cation, and zwitterion exchangers achieved by Lindner and his partners serves as an expansion of the range of the efficiently applicable CSPs.In this context this overview chapter discusses and summarizes direct enantiomer separations of chiral acids and ampholytes applying zwitterionic ion exchangers derived from Cinchona alkaloids. Our aim is to provide comprehensive information on practical solutions with focus on the molecular recognition and methodological variables.
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Affiliation(s)
- István Ilisz
- Institute of Pharmaceutical Analysis, University of Szeged, Szeged, Hungary.
| | - Attila Bajtai
- Institute of Pharmaceutical Analysis, University of Szeged, Szeged, Hungary
| | - Antal Péter
- Institute of Pharmaceutical Analysis, University of Szeged, Szeged, Hungary
| | - Wolfgang Lindner
- Department of Analytical Chemistry, University of Vienna, Vienna, Austria
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Foroughbakhshfasaei M, Szabó ZI, Mirzahosseini A, Horváth P, Tóth G. Enantiomeric quality control of R-Tofisopam by HPLC using polysaccharide-type chiral stationary phases in polar organic mode. Electrophoresis 2018; 39:2566-2574. [PMID: 29999177 DOI: 10.1002/elps.201800220] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/01/2018] [Indexed: 11/09/2022]
Abstract
A novel, fast and economic chiral HPLC method was developed and validated for the resolution of the four isomers of tofisopam. The separation capacity of eleven different chiral columns: six polysaccharide-type including three amylose-based (Chiralpak AD, Chiralpak AD-RH and Chiralpak AS) and three cellulose-based (Chiralcel OD, Chiralcel OJ and Lux Cellulose-4); three cyclodextrin- (Quest-BC, Quest-C2 and Quest-CM) and two macrocyclic glycopeptide antibiotic-type (Chirobiotic T and Chirobiotic TAG) were screened using polar organic or reversed-phase mode. Chiralpak AD, based on amylose tris(3,5-dimethylphenylcarbamate) as chiral selector with neat methanol was identified as the most promising system. In order to improve resolution, an orthogonal experimental design was employed, altering the concentration of 2-propanol, column temperature, and flow rate in a multivariate manner. Using the optimized method (85/15 v/v methanol/2-propanol, 40°C, flow rate: 0.7 mL/min) we were not only able to separate the four isomers but also detect 0.1% S-enantiomer as chiral impurity in R-tofisopam. This is important since the latter is under development as a single enantiomeric agent. Thermodynamic investigation revealed an unusual entropy and enthalpy-entropy co-driven controlled enantioseparation on Chiralcel OJ and on Chiralpak AD column, respectively. Our newly developed HPLC method was validated according to the ICH guidelines and its application was tested on a pharmaceutical formulation containing the racemic mixture of the drug. As a further novelty, a separate circular dichroism method was applied for the investigation of the interconversion kinetics of tofisopam conformers, which proved to be crucial for sample preparation and method validation.
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Affiliation(s)
| | - Zoltán-István Szabó
- Faculty of Pharmacy, University of Medicine and Pharmacy of Tîrgu Mureş, Romania
| | - Arash Mirzahosseini
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
| | - Péter Horváth
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
| | - Gergő Tóth
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary
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Ilisz I, Bajtai A, Lindner W, Péter A. Liquid chromatographic enantiomer separations applying chiral ion-exchangers based on Cinchona alkaloids. J Pharm Biomed Anal 2018; 159:127-152. [PMID: 29980014 DOI: 10.1016/j.jpba.2018.06.045] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 06/22/2018] [Accepted: 06/23/2018] [Indexed: 12/11/2022]
Abstract
As the understanding of the various biological actions of compounds with different stereochemistry has grown, the necessity to develop methods for the analytical qualification and quantification of chiral products has become particularly important. The last quarter of the century has seen a vast growth of diverse chiral technologies, including stereocontrolled synthesis and enantioselective separation and analysis concepts. By the introduction of covalently bonded silica-based chiral stationary phases (CSPs), the so-called direct liquid chromatographic (LC) methods of enantiomer separation became the state-of-the-art methodology. Although a large number of CSPs is available nowadays, the design and development of new chiral selectors and CSPs are still needed since it is obvious that in practice one needs a good portfolio of different CSPs and focused "chiral columns" to tackle the challenging tasks. This review discusses and summarizes direct enantiomer separations of chiral acids and ampholytes applying anionic and zwitterionic ion-exchangers derived from Cinchona alkaloids with emphasis on literature data published in the last 10 years. Our aim is to provide an overview of practical solutions, while focusing on the integration of molecular recognition and methodological variables.
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Affiliation(s)
- István Ilisz
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; Institute of Pharmaceutical Analysis, University of Szeged, Somogyi utca 4, H-6720 Szeged, Hungary.
| | - Attila Bajtai
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary
| | - Wolfgang Lindner
- Department of Analytical Chemistry, University of Vienna, Währinger Strasse 83, 1090 Vienna, Austria
| | - Antal Péter
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary
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