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Raikar P, Bannimath G. Recent Trends in Chiral Separation-A Collective Paradigm of Selected Chiral Impurities. CURR PHARM ANAL 2020. [DOI: 10.2174/1573412915666181219144507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Chiral separation plays a very important role in the modern pharmaceutical analysis and will
continue in upcoming years. Separation and identification of chiral impurities are indispensable. According
to ICH guidelines, only the active enantiomer of the drug has to be marketed, so there is a focus
on separation of the inactive enantiomer which acts as a chiral impurity. The impurities present in the
enantiomers also pose various toxic adverse effects on bioavailability and efficacy, hence the need to
separate these impurities will forever be trending. This review primarily focuses on the separation techniques
like Capillary Electrophoresis (CE), High-Performance Liquid Chromatography (HPLC), Gas
Chromatography (GC), and Supercritical Fluid Chromatography (SFC) followed by the year-wise trend
in the separation of selected chiral impurities. In the coming years, researchers should work on using
ultra-fast, selective, and sensitive methods for the effective separation of chiral impurities.
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Affiliation(s)
- Prachi Raikar
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education and Research, SS Nagar, Mysuru 570015, India
| | - Gurupadayya Bannimath
- Department of Pharmaceutical Chemistry, JSS College of Pharmacy, JSS Academy of Higher Education and Research, SS Nagar, Mysuru 570015, India
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2
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Synthesis, analytical characterization and capillary electrophoretic use of the single-isomer heptakis-(6-O-sulfobutyl)-beta-cyclodextrin. J Chromatogr A 2017; 1514:127-133. [DOI: 10.1016/j.chroma.2017.07.069] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/17/2017] [Accepted: 07/19/2017] [Indexed: 01/11/2023]
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3
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Chen FTA, Evangelista RA. Applications of Highly Sulfated Cyclodextrins for Enantiomeric Separation by Capillary Electrophoresis. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.199900115] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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4
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Application of charged single isomer derivatives of cyclodextrins in capillary electrophoresis for chiral analysis. J Chromatogr A 2010; 1217:953-67. [DOI: 10.1016/j.chroma.2009.11.094] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 11/30/2009] [Accepted: 11/30/2009] [Indexed: 11/19/2022]
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5
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Abstract
This paper summarizes the history of chiral separations done by using electromigration methods with CDs. Several enantioresolution mechanisms and a wide number of chiral selectors have been applied to the separation of optical isomers by CE. Among them inclusion-complexation with CDs or their derivatives played a very important role in CE. Since the beginning our group was involved in studying method optimization for enantiomer resolution by using these chiral selectors. One of our publications was the basis for further development in the field, at least for us. New chiral selectors, development of theory, new methodological approaches and a wide number of practical applications are the main results achieved in the last almost 25 years using CE as an enantioseparative technique.
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Affiliation(s)
- Salvatore Fanali
- Institute of Chemical Methodologies, National Council of Research, Area della Ricerca di Roma I, Monterotondo Scalo (Rome), Italy.
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6
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Li HF, Zeng H, Chen Z, Lin JM. Chip-based enantioselective open-tubular capillary electrochromatography using bovine serum albumin-gold nanoparticle conjugates as the stationary phase. Electrophoresis 2009; 30:1022-9. [DOI: 10.1002/elps.200800359] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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7
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Xiao Y, Ong TT, Tan TTY, Ng SC. Synthesis and application of a novel single-isomer mono-6-deoxy-6-(3R,4R-dihydroxypyrrolidine)-β-cyclodextrin chloride as a chiral selector in capillary electrophoresis. J Chromatogr A 2009; 1216:994-9. [DOI: 10.1016/j.chroma.2008.12.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 11/13/2008] [Accepted: 12/04/2008] [Indexed: 11/17/2022]
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8
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Jiang Z, Thorogate R, Smith NW. Highlighting the role of the hydroxyl position on the alkyl spacer of hydroxypropyl-β-cyclodextrin for enantioseparation in capillary electrophoresis. J Sep Sci 2008; 31:177-87. [DOI: 10.1002/jssc.200700266] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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9
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Shpigun OA, Ananieva IA, Budanova NY, Shapovalova EN. Use of cyclodextrins for separation of enantiomers. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc2003v072n12abeh000817] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Chankvetadze B. Enantioseparations by using capillary electrophoretic techniques. The story of 20 and a few more years. J Chromatogr A 2007; 1168:45-70; discussion 44. [PMID: 17765908 DOI: 10.1016/j.chroma.2007.08.008] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2007] [Revised: 07/27/2007] [Accepted: 08/02/2007] [Indexed: 11/29/2022]
Abstract
This paper provides the author's insight on the past, present and future of performing enantioseparations using capillary electrophoretic (CE) techniques. These techniques are discussed from the historical point of view, as well as based on their potential as the separation techniques of today and the future. The overview covers mechanistic as well as practical aspects of CE techniques.
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Affiliation(s)
- Bezhan Chankvetadze
- Institute of Chemistry, School of Exact and Natural Sciences and Molecular Recognition and Separation Science Laboratory, Tbilisi State University, Chavchavadze Ave. 1, 0128 Tbilisi, Georgia.
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11
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Lin CE, Cheng HT, Fang IJ, Liu YC, Kuo CM, Lin WY, Lin CH. Strategies for enantioseparations of catecholamines and structurally related compounds by capillary zone electrophoresis using sulfated β-cyclodextrins as chiral selectors. Electrophoresis 2006; 27:3443-51. [PMID: 16944458 DOI: 10.1002/elps.200500658] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Strategies for simultaneous enantioseparations of three catecholamines (DL-norepinephrine, DL-epinephrine, and DL-isoproterenol) and three structurally related compounds (DL-octopamine, DL-synephrine, and DL-norephedrine) by CZE using sulfated beta-CDs as chiral selectors were investigated. Four different separation modes were attempted: (I) using randomly sulfate-substituted beta-CD (MI-S-beta-CD) at relatively low concentrations in a high-concentration phosphate buffer at low pH in the normal polarity mode, (II) using MI-S-beta-CD at high concentrations at low pH in the reversed polarity mode, (III) using MI-S-beta-CD at moderately high concentrations in a phosphate buffer at neutral pH in the normal polarity mode, and (IV) using the single isomer heptakis(2,3-dihydroxy-6-O-sulfo)-beta-CD (SI-S-beta-CD) at low to moderately high concentrations in a high-concentration BGE at low pH in the normal polarity mode. Among them, enantioseparation of these cationic solutes was best achieved under the conditions of mode (II). In mode (II) and mode (III), temperature is an important factor affecting the enantioresolution of norepinephrine. In mode (I) and mode (IV), the use of a high-concentration BGE (150-200 mM) is crucial for effective enantioseparation of these cationic solutes with sulfated beta-CDs. Comparative studies of enantioseparations of these cationic solutes with MI-S-beta-CD and SI-S-beta-CD reveal that the sulfate substituents of MI-S-beta-CD located at the C(2)- position interact strongly with the diol moiety of catecholamines.
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Affiliation(s)
- Ching-Erh Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan.
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12
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Phinney KW, Ihara T, Sander LC. Determination of ephedrine alkaloid stereoisomers in dietary supplements by capillary electrophoresis. J Chromatogr A 2005; 1077:90-7. [PMID: 15988991 DOI: 10.1016/j.chroma.2005.04.068] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Three complementary capillary electrophoresis (CE) methods were developed for the separation and quantification of ephedrine and pseudoephedrine stereoisomers. Either single or dual cyclodextrin-based chiral selector systems provided enantioselective separation of the compounds of interest. The three methods were applied to the analysis of a suite of five standard reference materials (SRMs) containing ephedra. Use of a high-sensitivity UV detection cell enhanced quantification of the analytes of interest over the wide range of concentrations encountered in the SRMs. Results for (-)-ephedrine ranged from 0.31 to 76.43 mg/g, and for (+)-pseudoephedrine ranged from 0.049 to 9.23 mg/g in the materials studied. Results from the three methods agreed well with each other and with the results from other methods of analysis. The addition of known amounts of specific enantiomers was used to confirm the enantiomeric identity of the analytes. The results obtained by the three CE methods were utilized for value assignment of the ephedrine alkaloid content of these five SRMs.
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Affiliation(s)
- Karen W Phinney
- Analytical Chemistry Division, Chemical Science and Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8392, Gaithersburg, MD 20899-8392, USA.
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Amini A, Rundlöf T, Rydberg MBG, Arvidsson T. Characterization of sulfatedβ-cyclodextrins and determination of enantiomeric purity of (1R,2S)-ephedrine by capillary zone electrophoresis. J Sep Sci 2004; 27:1102-8. [PMID: 15495412 DOI: 10.1002/jssc.200401843] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize two different sulfated beta-cyclodextrins (HS-beta-CD). It was found that the HS-beta-CDs have broad heterogeneity in terms of sulfation degree. The average sulfate contents were in the range of 6 to 8 per CD molecule. Furthermore the sugar moieties of both HS-beta-CDs were sulfated either at position 6 or at positions 2 and 6, but not at position 3. Enantiomeric separation by capillary zone electrophoresis (CZE) using the HS-beta-CDs as chiral selectors showed that these CDs exhibited similar chiral selectivity and resolution of the ephedrine enantiomers. One of the CDs was employed for the enantiomeric purity evaluation of (1R,2S)-ephedrine (or (-)-ephedrine) by capillary zone electrophoresis. Quantification was done by comparison between the corrected peak areas of the minor enantiomer and (-)-ephedrine.
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Affiliation(s)
- Ahmad Amini
- Medical Products Agency (MPA), Laboratory, Box 26, Dag Hammarskjölds väg 42, 751 03 Uppsala, Sweden.
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14
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Zhang B, Krull IS, Cohen A, Smisek DL, Kloss A, Wang B, Bourque AJ. Separation of quaternary ammonium diastereomeric oligomers by capillary electrophoresis. J Chromatogr A 2004; 1034:213-20. [PMID: 15116933 DOI: 10.1016/j.chroma.2004.02.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The separation of novel diastereomeric trimers (3M) and pentamers (5M), derived from quaternary ammonium salts, was studied in conventional, uncoated and coated capillaries using capillary zone electrophoresis (CZE) with a variety of buffers and additives. Resolution of 5M diastereomers was best achieved using gamma-cyclodextrin (gamma-CD) as a chiral selector, while no diastereomeric resolution was realized for the 3M material.
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Affiliation(s)
- Bin Zhang
- Department of Chemistry, 102 Hurtig Hall, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
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15
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Evans CE, Stalcup AM. Comprehensive strategy for chiral separations using sulfated cyclodextrins in capillary electrophoresis. Chirality 2003; 15:709-23. [PMID: 12923809 DOI: 10.1002/chir.10285] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This review focuses on the emerging role of sulfated cyclodextrins in the capillary electrophoretic (CE) separation of chiral analytes. Since being introduced as enantioselective agents for CE in 1995, these anionic additives have continued to demonstrate remarkable application universality. The broad spectrum of chiral compounds successfully separated using this approach includes acidic, basic, neutral, and zwitterionic species. This impressive array of analyte structures is derived from a growing diversity of compound classes including pharmaceuticals, plant extracts, biomarkers, herbicides, alkaloids, fungicides, and metal ions. Moreover, literature reports highlight the minimal optimization required to achieve a successful separation. Based on these findings, sulfated cyclodextrins appear to be well suited for the development of a more universal, comprehensive separation strategy for chiral compounds. This review explores this proposition by beginning with the structure and migration properties of sulfated cyclodextrins, using applications to highlight the separating power of this technique and ending with a pragmatic, comprehensive separation strategy.
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Affiliation(s)
- Christine E Evans
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221-0172, USA
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16
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Mateus-Avois L, Mangin P, Saugy M. Development and validation of a capillary zone electrophoresis method for the determination of ephedrine and related compounds in urine without extraction. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 791:203-16. [PMID: 12798180 DOI: 10.1016/s1570-0232(03)00222-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A capillary zone electrophoresis (CZE) method, with UV detection and in the presence of dimethyl-beta-CD, was optimized by means of an experimental design for the separation and the simultaneous quantitation of ephedrine, pseudoephedrine, norephedrine (phenylpropanolamine) and norpseudoephedrine (cathine) in urine without any extraction. In this application, the optimization of the analytical conditions with an experimental design was preferred to a univariate study. Therefore, a central composite design was used and the following factors were investigated and varied simultaneously: buffer concentration, buffer pH and dimethyl-beta-CD concentration. In order to evaluate the influence of each experimental parameter on the analytical separation, the resolutions between the four compounds, as well as the separation time and generated current were observed and established as responses of the experimental design. A model was obtained for each response by linear multiple regression of a second-degree mathematical expression. After acceptance of the mathematical models, the most favorable conditions were determined by maximizing the resolutions between the four compounds and by setting the other responses at threshold values. Successful results were obtained with a 260 mM Tris-phosphate buffer at pH 3.5 in the presence of 13.3 mM dimethyl-beta-CD at 25 degrees C and with an applied voltage of 30 kV. Under these optimized conditions, a baseline separation of the four compounds was achieved in less than 6 min. The method was validated in terms of precision, linearity, accuracy and successfully applied for the determination of these compounds in urine samples without any extraction as well as in nutritional supplements.
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Affiliation(s)
- Lidia Mateus-Avois
- Laboratoire Suisse d'Analyse du Dopage, Institut Universitaire de Médecine Légale, Rue du Bugnon 21, 1005 Lausanne, Switzerland.
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17
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Aturki Z, Sinibaldi M. Separation of diastereomers of flavanone-7-O-glycosides by capillary electrophoresis using sulfobutyl ether-β-cyclodextrin as the selector. J Sep Sci 2003. [DOI: 10.1002/jssc.200301480] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Male KB, Luong JHT. Chiral analysis of neurotransmitters using cyclodextrin-modified capillary electrophoresis equipped with microfabricated interdigitated electrodes. J Chromatogr A 2003; 1003:167-78. [PMID: 12899306 DOI: 10.1016/s0021-9673(03)00817-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present cyclodextrin-modified capillary electrophoresis equipped with a microfabricated chip consisting of an array of eight interdigitated microband platinum electrodes (IDs) for simultaneous analysis of three chiral models: epinephrine, norepinephrine and isoproterenol. The IDE chip, positioned very close to the capillary outlet, served as an amplification/detection system. Emerging neurotransmitters at the IDE surface were oxidized at +1.1 V by seven electrodes of the array and then detected by the remaining electrode, poised at +0.0 V. There was an amplification effect on the detecting electrode owing to the recycle between the reduced and oxidized forms of the optical isomers at the electrode surface. The detecting "amplification" current response was governed by the applied potential, the detecting electrode position, the number of adjacent electrodes used for recycling and the distance between the oxidative and reductive electrodes. The six chiral forms of the three neurotransmitters were resolved using 25 mM heptakis(2,6,di-o-methyl)-beta-cyclodextrin with a detection limit of approximately 5 microM. The scheme detected a reduced compound at a reducing potential instead of conventional oxidation detection to alleviate electrode fouling and electroactive interferences. The concurrent oxidation/reduction detection of compounds also facilitated and ascertained peak identification as interfering compounds were unlikely to have the same oxidative/reductive characteristics and mobilities as the analytes of interrogation.
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Affiliation(s)
- Keith B Male
- Biotechnology Research Institute, National Research Council Canada, Montreal, Quebec, H4P 2R2 Canada
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19
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Wätzig H, Günter S. Capillary electrophoresis-a high performance analytical separation technique. Clin Chem Lab Med 2003; 41:724-38. [PMID: 12880135 DOI: 10.1515/cclm.2003.112] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Capillary electrophoresis (CE) is often one of the preferred techniques in pharmaceutical quality control and in clinical chemistry, particularly considering the high selectivity and lower costs compared to HPLC. The precision of CE is as good as in liquid chromatography (LC). The sample-throughput is high due to short analysis times. Efforts for sample pre-treatment are usually minor in CE. Urine and even blood plasma can be directly injected without further pre-treatment. After summarising the basic principles of CE, general strategies for method development are described to achieve selective, efficient, precise, fast, sensitive, and validated methods. Sample pre-treatment requirements are discussed. Standard buffer recipes, surfactants used in micellar electrokinetic chromatography (MEKC), chiral selectors, useful buffer additives, actions to deal with complex matrices, and aspects of validation have been collected. Other techniques that can be performed with CE instruments, such as capillary isoelectric focusing (CIEF), capillary isotachophoresis (CITP), and capillary electrochromatography (CEC), are briefly discussed.
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Affiliation(s)
- Hermann Wätzig
- Institute for Pharmaceutical Chemistry, Technical University Braunschweig, Braunschweig, Germany.
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20
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Schmitt U, Branch SK, Holzgrabe U. Chiral separations by cyclodextrin-modified capillary electrophoresis - Determination of the enantiomeric excess. J Sep Sci 2002. [DOI: 10.1002/1615-9314(20021101)25:15/17<959::aid-jssc959>3.0.co;2-q] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Marusza W, Trojanowicz M, Margasińska M, Engelhardt H. Application of carboxymethyl-beta-cyclodextrin as a chiral selector in capillary electrophoresis for enantiomer separation of selected neurotransmitters. J Chromatogr A 2001; 926:327-36. [PMID: 11556337 DOI: 10.1016/s0021-9673(01)01076-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The aim of this work was to optimize conditions for capillary electrophoresis separation of different neurotransmitters (serotonin, phenylalanine, dopamine, adrenaline, ephedrine, propranolol and DOPA) in a single run, including separation of existing enantiomers. As chiral selectors added to the borate background, electrolyte unsubstituted alpha-, beta- and -gamma-cyclodextrins (CDs), methyl-, dimethyl-, and trimethyl-substituted beta-CDs, and hydroxypropyl-substituted alpha-, beta- and gamma-CDs were examined. Also carboxymethyl-beta-CD and succinyl-beta-CD were used for this purpose. In addition to the kind and concentration of chiral selector, some other experimental factors also have been optimized, such as concentration of borate buffer, content of methanol, pH of electrolyte, method of sample introduction into the capillary and washing procedure between consecutive runs. The best results were obtained using 20 mM carboxymethyl-beta-CD in borate buffer of pH 7.5 as running electrolyte and hydrostatic injection. The obtained sensitivity of response (peak height) varied from 0.4 for adrenalines to 2.3 mAU mM(-1) for propranolols. The concentration detection limits (S/N=3) were in the range from 0.04 mM for propranolols to 0.2 mM for adrenalines. The resolution obtained in optimized conditions in a single run was from 0.75 for adrenalins and 1.0 for propranolols up to 2.0 for ephedrines. The developed method was employed for determination of these analytes in brain tissue extracts.
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Affiliation(s)
- W Marusza
- Department of Chemistry, Warsaw University, Poland
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Grard S, Elfakir C, Dreux M. Analysis of sulfobutyl ether-beta-cyclodextrin mixtures by ion-spray mass spectrometry and liquid chromatography-ion-spray mass spectrometry. J Chromatogr A 2001; 925:79-87. [PMID: 11519819 DOI: 10.1016/s0021-9673(01)01007-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The analysis of two commercial and two home-made sulfobutyl ether beta-cyclodextrin (SBE-beta-CD) samples by ion-spray (IS) mass spectrometry and by liquid chromatography-mass spectrometry coupling (LC-MS) is investigated in a negative ion mode. SBE-beta-CD fragmentation was first investigated by direct infusion. In IS, the best conditions for SBE-beta-CD ionization consisted of ammonium acetate added to an acetonitrile/water mixture as sample solvent. These conditions allowed simplification of the mass spectrum, mainly by the formation of dicharged species [M-2H]2-, thus limiting the production of multicharged fragments. IS-MS permits fast and simple measurement of the substitution pattern and determination of the global degree of substitution for SBE-beta-CD mixtures. A complementary method using LC-MS was developed for the analysis of these mixtures. The substitution patterns obtained by LC-MS are in good agreement with those determined by direct MS analysis. The LC-MS coupling enabled separation of the mixtures versus the charge in anion-exchange chromatography (AEC) whereas no separation of the different substitution isomers potentially present in the SBE-beta-CD mixture was displayed. The AEC methodology described can be successfully used for fractionation of SBE-beta-CD derivatives at the semi-preparative scale.
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Affiliation(s)
- S Grard
- Institut de Chimie Organique et Analytique, ICOA, CNRS-UMR 6005, Université d'Orléans, France
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Abstract
A class of highly sulfated cyclodextrins (HS-CDs) was developed for enantiomeric separation of chiral compounds by capillary electrophoresis (CE). The HS-CDs were produced by a facile single-step direct sulfation of cyclodextrin using sulfur trioxide-trimethylamine complex in dimethylformamide. Characterization of the HS-CDs by electrospray ionization mass spectrometry and by CE using a well-established indirect detection method indicated the species have very narrow heterogeneity in terms of degree of sulfation. Elemental analysis of the HS-alpha-, beta- and gamma-CDs showed that the average sulfate contents were 11, 12, and 13 per CD molecule, respectively. The 13C NMR of HS-CDs is consistent with the structural assignment of nearly complete sulfation at C-6 primary hydroxyl groups and partial sulfation at the C-2 secondary hydroxyls (>70%), while the C-3 hydroxyls remain unsubstituted. Enantiomeric separation by CE using the HS-CDs as chiral selectors showed that HS-alpha-, beta- and gamma-CDs complement each other by exhibiting different chiral selectivities, resulting in resolution of many chiral neutral, acidic and basic compounds of greatly varying structural features. The part of HS-CD that interacts with the guest molecule during complexation and, therefore, the receiving end of the cyclodextrin hydrophobic bucket was surrounded with largely regiospecifically substituted C-2 sulfates and intact C-3 hydroxyls, both at the equatorial positions. Such global regiospecific structural arrangement in HS-CDs provides differential diasteroisomeric complexation is proposed to be the principal contributing factor in the resolving racemates.
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Affiliation(s)
- F T Chen
- Beckman Coulter, Inc., Fullerton, CA 92835, USA.
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24
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Yang WC, Yu AM, Yu XD, Chen HY. Modeling and optimization of the chiral selectivity of basic analytes in chiral capillary electrophoresis with negatively charged cyclodextrins using electrochemical detection. Electrophoresis 2001; 22:2025-31. [PMID: 11465502 DOI: 10.1002/1522-2683(200106)22:10<2025::aid-elps2025>3.0.co;2-m] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A mathematical model concerning the separation selectivity of basic analytes in chiral capillary electrophoresis (CE) modified with negatively charged cyclodextrins (CDs) has been presented to describe the dependence of chiral selectivity on the buffer pH and the chiral selector concentration. The electrophoretic method to determine the parameters of the model has also been developed. The model has been tested with racemic epinephrine and isoproterenol as target analytes and sulfonated beta-CD as chiral selector. The agreements have been found between the calculated and the measured values. Some significant conclusions to optimize chiral CE separation have been derived from the model and proven by the experiments. Electrochemical detection was used to meet the requirement of the low introduced concentration of analytes.
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Affiliation(s)
- W C Yang
- Department of Chemistry, Nanjing University, PR China
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25
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Bhushan R, Martens J, Arora M. Direct resolution of (+/-)-ephedrine and atropine into their enantiomers by impregnated TLC. Biomed Chromatogr 2001; 15:151-4. [PMID: 11391670 DOI: 10.1002/bmc.55] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Direct resolution of (+/-)-ephedrine and atropine into their enantiomers was achieved by normal-phase thin layer chromatography on silica gel plates impregnated with optically pure L-tartaric acid and L-histidine, respectively, as chiral selectors. The mobile phases enabling successful resolution were different combinations of acetonitrile-methanol-water. The spots were detected with iodine vapours and the detection limits were 2 and 6 microg, respectively, in terms of the racemate. The effects of concentration of the impregnating reagent, temperature and pH on resolution have been studied.
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Affiliation(s)
- R Bhushan
- Department of Chemistry, University of Roorkee, Roorkee 247 667, India
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26
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Grard S, Elfakir C, Dreux M. Characterization of sulfobutyl ether-beta-cyclodextrins mixtures by anion-exchange chromatography using evaporative light scattering detection. J Chromatogr A 2000; 897:185-93. [PMID: 11128202 DOI: 10.1016/s0021-9673(00)00816-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
An analytical method based on anion-exchange chromatography (AEC) using volatile eluent ion and evaporative light scattering detection was developed for the analysis of mixtures of sulfobutyl-ether-beta-cyclodextrins (SBE-beta-CDs). A systematic investigation of the retention mechanism of pure SBE-beta-CD standards has been studied on a silica quaternary ammonium exchanger (Vydac 302 IC column). The influence of the nature and concentration of volatile anions (acetate, formate, trifluoroacetate), the addition of the organic modifier in the mobile phase as well the nature of the stationary phase have been evaluated under isocratic elution conditions. Satisfactory analysis of two commercial and two home-made SBE-beta-CD samples was achieved on the Vydac 302 IC column by using ammonium acetate as ion eluent in water-acetonitrile (70:30) under a salt concentration gradient mode. This method provides for SBE-beta-CD samples, an efficient and characteristic liquid chromatography fingerprint which depicts the mixture complexity and determines an average degree of substitution (DS) for each sample.
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Affiliation(s)
- S Grard
- Institut de Chimie Organique et Analytique, ICOA, CNRS-UPRES-A 6005, Université d'Orleans, France
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27
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de Boer T, de Zeeuw RA, de Jong GJ, Ensing K. Recent innovations in the use of charged cyclodextrins in capillary electrophoresis for chiral separations in pharmaceutical analysis. Electrophoresis 2000; 21:3220-39. [PMID: 11001221 DOI: 10.1002/1522-2683(20000901)21:15<3220::aid-elps3220>3.0.co;2-x] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A review is presented on the use of charged cyclodextrins (CDs) as chiral selectors in capillary electrophoresis (CE) for the separation of analytes in pharmaceutical analysis. An overview is given of theoretical models that have been developed for a better prediction of the enantiomeric resolution and for a better understanding of the separation mechanism. Several types of charged CDs have been used in chiral capillary electrophoretic separation (anionic, cationic, and amphoteric CDs). Especially the anionic CDs seem to be valuable due to the fact that many pharmaceutically interesting compounds can easily be protonated (e.g., amine groups). For that reason several anionic CDs are now commercially available. Cationic and amphoteric CDs are less common in chiral analysis and only a few are commercially available. Attention is paid to the most common synthesis routes and the characterization of the CDs used in chiral capillary electrophoretic separations. The degree of substitution in the synthesized CDs may vary from one manufacturer to another or even from batch to batch, which may have a detrimental effect on the reproducibility and ruggedness of the separation system. In Sections 4, 5, and 6 the applications of anionic, cationic, and amphoteric CDs for the chiral separation in CE are described. Many interesting examples are shown and the influence of important parameters on the enantioselectivity is discussed.
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Affiliation(s)
- T de Boer
- Department of Analytical Chemistry and Toxicology, University Center for Pharmacy, Groningen, The Netherlands.
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28
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Rudaz S, Stella C, Balant-Gorgia AE, Fanali S, Veuthey JL. Simultaneous stereoselective analysis of venlafaxine and O-desmethylvenlafaxine enantiomers in clinical samples by capillary electrophoresis using charged cyclodextrins. J Pharm Biomed Anal 2000; 23:107-15. [PMID: 10898160 DOI: 10.1016/s0731-7085(00)00280-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Capillary electrophoresis (CE) was used for the simultaneous chiral determination of venlafaxine (Vx), a new antidepressant drug and its main active metabolite. O-desmethyl venlafaxine (ODV). Among the charged cyclodextrins (CD) tested, phosphated gamma-CD was the most appropriate. Resolution of Vx and ODV was obtained with 50 mM phosphate buffer (pH 2.5) containing 20 mg/ml of phosphated gamma-CD. After optimisation of the method (including robustness), validation was carried out. Vx and ODV concentrations, as well as the enantiomeric ratio, were investigated in clinical samples. Chiral determination of Vx and ODV was performed after a simple liquid-liquid extraction (LLE). In the tested concentration range (25-500 ng/ml), coefficients of correlation were superior to 0.996. Within-day and between-day accuracy and precision were determined at three different concentrations for each enantiomer. Analyses of clinical samples (n = 16) exhibited non-racemic ratios for Vx and ODV, which suggests a stereoselective metabolism in humans.
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Affiliation(s)
- S Rudaz
- Laboratory of Pharmaceutical Analytical Chemistry, University of Geneva, Switzerland
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29
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Grard S, Morin P, Dreux M, Ribet JP. Enhancement of second-migrating enantiomer peak symmetry of basic drugs by using dual-cyclodextrin system in capillary electrophoresis. Electrophoresis 2000; 21:3028-34. [PMID: 11001320 DOI: 10.1002/1522-2683(20000801)21:14<3028::aid-elps3028>3.0.co;2-#] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Today, chiral separations of cationic drugs by capillary electrophoresis are generally carried out by adding negatively charged cyclodextrins (CDs) to the running buffer while anionic or neutral drug separations require the use of dual-CD systems (mixtures of neutral and charged CDs). Chiral separation of some basic drugs (idazoxan, efaroxan, milnacipran) has been studied by using mixtures of sulfated-beta-CD (S-beta-CD) and hydroxypropyl-gamma-CD (HP-gamma-CD). The influence of the following parameters (nature and concentration of neutral CD, concentration of S-gamma-CD) on many separation factors (electrophoretic mobility, selectivity, efficiency, asymmetry factor, resolution) demonstrated that dual-CD systems are useful for chiral separation of basic drugs in order to improve the symmetry of the second-migrating enantiomer. Indeed, the neutral CD reduces the extent of electromigration dispersion by mobility tuning. Finally, the 0.5 mg/mL S-beta-CD/5 mg/mL HP-gamma-CD dual system has allowed the chiral separation of idazoxan, efaroxan and milnacipran enantiomers in less than 9 min.
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Affiliation(s)
- S Grard
- Institute of Organic and Analytical Chemistry, University of Orleans, France
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30
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Lehmann SV, Breinholt J, Bury PS, Nielsen TE. Enzymatic resolution to (-)-ormeloxifene intermediates from their racemates using immobilized Candida rugosa lipase. Chirality 2000; 12:568-73. [PMID: 10861957 DOI: 10.1002/1520-636x(2000)12:7<568::aid-chir4>3.0.co;2-u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the synthesis of (-)-ormeloxifene, a drug candidate recently under development, enzymatic resolution of potential intermediates can be carried out using a simple, practical method. Five commercially available lipases, Candida rugosa lipase, Candida antarctica lipase B, Mucor miehei lipase, Pseudomonas cepacia lipase, and Humicola lanuginosa lipase, all immobilized on Accurel(R), were initially screened in combination with four different substrates belonging to the class of phenyl esters. Excellent stereoselectivity was observed using C. rugosa lipase with an acetate as substrate, but low reaction rates were observed in scale-up experiments. However, by changing the acyl part of the ester into a hexanoyl moiety and subjecting this substrate to enzymatic hydrolysis in aqueous acetonitrile at room temperature by C. rugosa lipase, it became possible to run the reaction to a 50% conversion on a 10 g scale within a period of 4 h, obtaining a phenolic product of more than 95% ee that could be converted to the target molecule, (-)-ormeloxifene, in two synthetic steps. Simple recovery of the immobilized enzyme by filtration allowed multiple recycling of the catalyst without significant loss of enzymatic activity. Capillary electrophoresis with sulfobutyl ether beta-cyclodextrin as a chiral buffer additive and acetonitrile as an organic modifier was demonstrated to provide an excellent chiral analytical tool for monitoring the enzymatic reactions.
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Affiliation(s)
- S V Lehmann
- Analytical Development, Pharmaceuticals Development, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark.
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31
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Perrin C, Vargas MG, Heyden YV, Maftouh M, Massart DL. Fast development of separation methods for the chiral analysis of amino acid derivatives using capillary electrophoresis and experimental designs. J Chromatogr A 2000; 883:249-65. [PMID: 10910218 DOI: 10.1016/s0021-9673(00)00377-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The use of experimental design in method development was studied for the chiral separation of several amino acid derivatives with capillary electrophoresis. The aim of this study was to define rapidly experimental conditions under which the enantiomers can be sufficiently separated for quantification and to derive a methodology for the separation of new compounds. Three modified cyclodextrins (CDs) were used as chiral selectors: hydroxypropyl-beta-cyclodextrin, carboxymethyl-beta-CD and sulfobutylether-beta-CD. The following factors were examined: the type of cyclodextrin, the CD concentration, the pH and the % of organic modifier (methanol) of the electrolyte. Two types of fractional factorial design were used depending on the type of analyte and on the number of factors selected: a 3(4-2) fractional factorial design (4 factors studied at 3 different levels) and a 2(3-1) fractional factorial design (3 factors at 2 different levels). From the 14 compounds investigated, 12 could be separated with one or another CD and not more than 9 experiments were required. No generalisation of the best analysis conditions was possible within this family of compounds. Specific analysis conditions must be defined for each analyte. Experimental designs have shown to be very useful to determine rapidly conditions under which each enantiomer can be separated with an acceptable resolution.
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Affiliation(s)
- C Perrin
- Department of Pharmaceutical and Biomedical Analysis, Pharmaceutical Institute, Vrije Universiteit Brussel, Brussels, Belgium
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32
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Zhu W, Vigh G. Experimental verification of a predicted, hitherto unseen separation selectivity pattern in the nonaqueous capillary electrophoretic separation of weak base enantiomers by octakis (2,3-diacetyl-6-sulfato)-gamma-cyclodextrin. Electrophoresis 2000; 21:2016-24. [PMID: 10879961 DOI: 10.1002/1522-2683(20000601)21:10<2016::aid-elps2016>3.0.co;2-l] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The capillary electrophoretic separation of cationic enantiomers with single-isomer multivalent anionic resolving agents was reexamined with the help of the charged resolving agent migration model. Three general model parameters were identified that influence the shape of the separation selectivity and enantiomer mobility difference curves: parameter b, the binding selectivity (K(RCD)/K(SCD)), parameter s, the size selectivity (mu0(RCD)/mu0(SCD)), and parameter a, the complexation-induced alteration of the analyte's mobility (mu0(RCD)/mu0). In addition to the previously observed discontinuity in separation selectivity that occurs as mu(eff) of the less mobile enantiomer changes from cationic to anionic, a new feature, a separation selectivity maximum was predicted to occur in the resolving agent concentration range where both enantiomers migrate cationically provided that (i) K(RCD)/K(SCD) <1 and mu0(RCD)/mu0(SCD) >1 and (K(RCD)mu0(RCD))/(K(SCD)mu0(SCD)) > 1, or (ii) K(RCD)/K(SCD) >1 and mu0(RCD)/mu0(SCD) <1 and (K(RCD)mu0(RCD))/(K(SCD)mu0(SCD)) <1. This hitherto unseen separation selectivity pattern was experimentally verified during the nonaqueous capillary electrophoretic separation of the enantiomers of four weak base analytes in acidic methanol background electrolytes with octakis(2,3-diacetyl-6-sulfato)-gamma-cyclodextrin (ODAS-gammaCD) as resolving agent.
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Affiliation(s)
- W Zhu
- Texas A&M University, Department of Chemistry, College Station 77842-3012, USA
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33
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Fanali S. Enantioselective determination by capillary electrophoresis with cyclodextrins as chiral selectors. J Chromatogr A 2000; 875:89-122. [PMID: 10839140 DOI: 10.1016/s0021-9673(99)01309-6] [Citation(s) in RCA: 340] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
This review surveys the separation of enantiomers by capillary electrophoresis using cyclodextrins as chiral selector. Cyclodextrins or their derivatives have been widely employed for the direct chiral resolution of a wide number of enantiomers, mainly of pharmaceutical interest, selected examples are reported in the tables. For method optimisation, several parameters influencing the enantioresolution, e.g., cyclodextrin type and concentration, buffer pH and composition, presence of organic solvents or complexing additives in the buffer were considered and discussed. Finally, selected applications to real samples such as pharmaceutical formulations, biological and medical samples are also discussed.
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Affiliation(s)
- S Fanali
- Istituto di Cromatografia del C.N.R., Area della Ricerca di Roma, Monterotondo Scalo (Rome), Italy.
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34
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Lucangioli SE, Hermida LG, Tripodi VP, Rodríguez VP, López EE, Rouge PD, Carducci CN. Analysis of cis-trans isomers and enantiomers of sertraline by cyclodextrin-modified micellar electrokinetic chromatography. J Chromatogr A 2000; 871:207-15. [PMID: 10735301 DOI: 10.1016/s0021-9673(99)00881-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In this work development, optimization and validation of a cyclodextrin-modified micellar electrokinetic chromatography (CD-modified MEKC) method is proposed to resolve separation of the sertraline hydrochloride and synthesis-related substances. Sertraline hydrochloride, the cis-(1S,4S) enantiomer form, is used as an antidepressant therapeutic agent. A buffer concentration composed of 20 mM sodium borate, pH 9.0 with 50 mM sodium cholate, 15 mM sulfated beta-cyclodextrin and 5 mM hydroxypropyl-beta-cyclodextrin was found to be the most suitable background electrolyte. Quantitation of the impurities at levels of 0.1% in different samples of the bulk drug was determined. A comparison of the results with those obtained by HPLC methodology was also accomplished. The method proved appropriate for testing the purity of sertraline hydrochloride in bulk drug.
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Affiliation(s)
- S E Lucangioli
- Faculty of Pharmacy and Biochemistry, Department of Analytical Chemistry and Physicochemistry, University of Buenos Aires, Junín, Argentina
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35
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Mateus L, Cherkaoui S, Christen P, Veuthey JL. Enantioseparation of atropine by capillary electrophoresis using sulfated beta-cyclodextrin: application to a plant extract. J Chromatogr A 2000; 868:285-94. [PMID: 10701678 DOI: 10.1016/s0021-9673(99)01230-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A capillary zone electrophoresis (CZE) method, with sulfated beta-CD as chiral selector, was optimized by means of an experimental design for the enantioseparation of atropine. In this study, a central composite design was used and the following factors were varied simultaneously: buffer concentration, buffer pH and sulfated beta-CD concentration. The resolutions between littorine and its positional isomer ((-)-hyoscyamine) and between atropine enantiomers, as well as the separation time and generated current were established as responses. A model was obtained for each response by linear multiple regression of a second-degree mathematical expression. The most favorable conditions were determined by maximizing the resolution between atropine enantiomers and by setting the other responses at threshold values. Successful results were obtained with a 55 mM phosphate buffer at pH 7 in the presence of 2.9 mM sulfated-beta-CD at 20 degrees C and 20 kV. Under these optimized conditions, a baseline separation of littorine and atropine enantiomers was achieved in less than 5 min. Finally, the method allowed the enantiomeric separation of atropine in a pharmaceutical formulation and was also found to be suitable for the enantiomeric purity evaluation of (-)-hyoscyamine in plant extracts, in relation with the extraction procedure. It was demonstrated that supercritical fluid extraction induced less racemization than classical liquid-solid extraction procedures.
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Affiliation(s)
- L Mateus
- Laboratory of Pharmaceutical Analytical Chemistry, University of Geneva, Switzerland
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36
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Zhu W, Vigh G. Capillary electrophoretic separation of the enantiomers of weak acids in a high pH background electrolyte using the new, single-isomer, octakis(2,3-diacetyl-6-sulfato)-?-cyclodextrin as chiral resolving agent. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/(sici)1520-667x(2000)12:3<167::aid-mcs6>3.0.co;2-l] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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37
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Mercier JP, Debrun JL, Dreux M, Elfakir C, Hakim B. Mass spectrometric study of randomly methylated beta-cyclodextrins using ionspray, atmospheric pressure chemical ionization and matrix-assisted laser desorption/ionization. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2000; 14:68-70. [PMID: 10623931 DOI: 10.1002/(sici)1097-0231(20000130)14:2<68::aid-rcm835>3.0.co;2-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mixtures of methylated beta-cyclodextrins were characterized using three different methods of mass spectrometry: ionspray, atmospheric pressure chemical ionization (APCI) and matrix-assisted laser desorption/ionization (MALDI). Each of these methods allows a fast and simple determination of the degree of substitution, and can provide evidence for differences in the methylation of batches which have very similar global degrees of substitution. The three methods are in good qualitative agreement, but there are systematic differences in the quantitative results for the percentages of the various methylated molecules present in a batch. This is attributed to ionization yields which increase with the number of methyl groups, with different slopes for the different methods.
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Affiliation(s)
- J P Mercier
- Institut de Chimie Organique et Analytique, UFR Sciences, Universit¿e d'Orl¿eans, BP 6759, 45067 Orleans, France
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38
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Abstract
This review gives a survey of selectivity modes in capillary electrophoresis separations in pharmaceutical analysis and bioanalysis. Despite the high efficiencies of these separation techniques, good selectivity is required to allow quantitation or identification of a particular analyte. Selectivity in capillary electrophoresis is defined and described for different separation mechanisms, which are divided into two major areas: (i) capillary zone electrophoresis and (ii) electrokinetic chromatography. The first area describes aqueous (with or without organic modifiers) and nonaqueous modes. The second area discusses all capillary electrophoretic separation modes in which interaction with a (pseudo)stationary phase results in a change in migration rate of the analytes. These can be divided in micellar electrokinetic chromatography and capillary electrochromatography. The latter category can range from fully packed capillaries, via open-tubular coated capillaries to the addition of microparticles with multiple or single binding sites. Furthermore, an attempt is made to differentiate between methods in which molecular recognition plays a predominant role and methods in which the selectivity depends on overall differences in physicochemical properties between the analytes. The calculation of the resolution for the different separation modes and the requirements for qualitative and quantitative analysis are discussed. It is anticipated that selectivity tuning is easier in separation modes in which molecular recognition plays a role. However, sufficient attention needs to be paid to the efficiency of the system in that it not only affects resolution but also detectability of the analyte of interest.
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Affiliation(s)
- T de Boer
- Department of Analytical Chemistry and Toxicology, University Center for Pharmacy, Groningen, The Netherlands.
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39
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Vargas MG, Vander Heyden Y, Maftouh M, Massart DL. Rapid development of the enantiomeric separation of beta-blockers by capillary electrophoresis using an experimental design approach. J Chromatogr A 1999; 855:681-93. [PMID: 10519104 DOI: 10.1016/s0021-9673(99)00701-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A rapid method for determining the separation conditions for chiral resolution of eleven beta-blocking drug substances by capillary electrophoresis is described, using an experimental design approach. An acidic phosphate-triethanolamine buffer and an uncoated fused-silica capillary were used for all experiments. Several modified cyclodextrins were applied as chiral selectors: sulfobutyl ether beta-cyclodextrin (SBE-beta CD), dimethyl beta-cyclodextrin (DM-beta CD), carboxymethyl beta-cyclodextrin (CM-beta CD), and hydroxypropyl beta-cyclodextrin (HP-beta CD). Two different fractional factorial experimental designs were applied: (1) a design examining four factors at three levels (3(4-2)) and (2) one examining three factors at two levels (2(3-1)). The factors studied were: type of cyclodextrin, cyclodextrin concentration, pH of the background electrolyte and percentage of organic modifier. Enough resolution for the separation of the enantiomers and even for their quantification was reached. The same scheme is proposed when a fast chiral separation method needs to be developed for other drug families.
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Affiliation(s)
- M G Vargas
- Department of Pharmaceutical and Biomedical Analysis, Vrije Universiteit Brussel, Belgium
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40
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Wedig M, Holzgrabe U. Resolution of ephedrine derivatives by means of neutral and sulfated heptakis(2,3-di-O-acetyl)beta-cyclodextrins using capillary electrophoresis and nuclear magnetic resonance spectroscopy. Electrophoresis 1999; 20:2698-704. [PMID: 10532337 DOI: 10.1002/(sici)1522-2683(19990901)20:13<2698::aid-elps2698>3.0.co;2-n] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Beta-cyclodextrin (beta-CD), heptakis(2,3-di-O-acetyl)beta-cyclodextrin (Diac-beta-CD) and heptakis (2,3-di-O-acetyl-6-sulfato)beta-cyclodextrin (HDAS-beta-CD) were tested for their ability to discriminate the enantiomers of ephedrine, pseudoephedrine, norephedrine and methylephedrine. Using capillary electrophoresis (CE) under optimized conditions, with the exception of norephedrine in presence of beta-CD, all racemates could be resolved. Utilizing Job's plot by means of UV spectroscopy revealed 1:1 complexes formed with beta-CD and Diac-beta-CD. HDAS-beta-CD gave curved plots indicating mixed stoichiometry. Inspection of the cyclodextrin-induced chemical shifts (CICS) of both the ligands and the CDs showed that the ephedrine sits deeply in the cavity of beta-CD and HDAS-beta-CD. In the case of Diac-beta-CD, the ephedrine is located closely to the wider rim of the CD cavity. In conclusion, comparing the pattern of CICS of the various CD derivatives clearly indicates the differences in the complex geometry.
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Affiliation(s)
- M Wedig
- Pharmaceutical Institute, University of Würzburg, Germany
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41
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Skanchy DJ, Xie GH, Tait RJ, Luna E, Demarest C, Stobaugh JF. Application of sulfobutylether-beta-cyclodextrin with specific degrees of substitution for the enantioseparation of pharmaceutical mixtures by capillary electrophoresis. Electrophoresis 1999; 20:2638-49. [PMID: 10532329 DOI: 10.1002/(sici)1522-2683(19990901)20:13<2638::aid-elps2638>3.0.co;2-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this research the separation of the enantiomers of the basic drug bidisomide (SC-40230) from five closely related known process impurities was investigated using several neutral and anionic sulfobutylether beta-cyclodextrins (SBE-beta-CDs) as isomer selectors. Several novel sulfobutylether derivative mixtures and purified charge types having a specific degree of substitution were used to study the effect of selector charge on the efficiency and selectivity of both chiral and achiral separations. The effects of run buffer pH, selector type, and selector concentration on the chiral separation of bidisomide and the achiral separation of the related process impurities was also investigated. The related process impurity, SC-47500, displayed significant peak tailing with SBE-beta-CD mixtures which contained mono- to deca-substituted cyclodextrins. This problem was explored using isolated SBE-beta-CD charge types having degrees of substitution from one to seven. Peak tailing increased as the charge on the selector increased, suggesting that the distortion was due to electrodispersion and the large countercurrent mobility of the negatively charged complexes. Pure charge types having a lower degree of substitution provided adequate chiral and achiral selectivity, while eliminating the severe peak distortion caused by electrodispersion. The complete analysis of the bidisomide enantiomers and the related impurities was achieved with a pH 2.5 running buffer containing 5-10 mM of the isolated sulfobutylether charge types SBE[2]ds(1)sr-beta-CD or SBE[3]ds(1)sr-beta-CD. These conditions gave baseline resolution of bidisomide enantiomers and all five impurities, thus allowing both chiral and achiral purity to be determined in a single run.
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Affiliation(s)
- D J Skanchy
- Department of Pharmaceutical Chemistry, Center for Bioanalytical Research, The University of Kansas, Lawrence 66047, USA
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42
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Ren X, Dong Y, Liu J, Huang A, Liu H, Sun Y, Sun Z. Separation of chiral basic drugs with sulfobutyl-β-cyclodextrin in capillary electrophoresis. Chromatographia 1999. [DOI: 10.1007/bf02490843] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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43
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Abstract
This review discusses selected aspects of selector-select and interactions in chiral capillary electrophoresis (CE). Studies performed using nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry (MS) and X-ray crystallography for a better understanding of chiral recognition mechanisms in CE are summarized. The theoretical background of chiral CE in general, mathematical models, method development and optimization strategies, etc., are not covered. A general overview on the most recent developments in chiral CE is presented in this volume in the review paper by Bocek [1].
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Affiliation(s)
- B Chankvetadze
- Institute of Pharmaceutical Chemistry, University of Münster, Germany.
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Wang F, Khaledi MG. Non-aqueous capillary electrophoresis chiral separations with sulfated beta-cyclodextrin. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 1999; 731:187-97. [PMID: 10510771 DOI: 10.1016/s0378-4347(99)00217-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper reports the application of an anionic cyclodextrin (CD), sulfated beta-cyclodextrin with a degree of substitution of four (beta-CD-(SO4-)4, in chiral separations of pharmaceutical enantiomers by non-aqueous capillary electrophoresis (NACE). Upon complexation with the anionic CD, electrophoretic mobilities of the basic enantiomers decreased, however, both separation selectivity and resolution were enhanced. The advantage of NACE chiral separations over the aqueous CE with the charged CD is that higher electric field strength and higher ionic strength could be applied due to the characteristics of the solvent formamide. The higher ionic strength leads to stacking of peaks and reduces the electrodispersion caused by the mobility mismatch between beta-CD-(SO4-)4-analyte complexes and the co-ions in the running buffer. As a result, better peak shapes and higher separation efficiency were obtained. Comparing with NACE chiral separations with neutral CDs, lower concentration of beta-CD-(SO4-)4 was needed due to the fact that the electrostatic attraction caused stronger binding between beta-CD-(SO4-)4 and the enantiomers. The effects of the experimental parameters, such as concentration of the CD, apparent pH (pH*), degree of substitutions of the CDs, percentage of water in mixed solvent systems, and type of solvents were also studied.
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Affiliation(s)
- F Wang
- Department of Chemistry, North Carolina State University, Raleigh 27695-8204, USA
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Rudaz S, Veuthey JL, Desiderio C, Fanali S. Use of cyclodextrins in capillary electrophoresis: resolution of tramadol enantiomers. Electrophoresis 1998; 19:2883-9. [PMID: 9870383 DOI: 10.1002/elps.1150191614] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Capillary zone electrophoresis was successfully applied to the enantiomeric resolution of racemic tramadol. Both uncoated and polyacrylamide-coated capillaries were tested for method optimization using either negatively charged or native cyclodextrins (CD) added to the background electrolyte (BGE). The resolution was strongly influenced by the CD type and concentration as well as by the pH and the concentration of the BGE. Among the CDs tested, carboxymethylated-beta-cyclodextrin allowed the baseline separation of tramadol enantiomers. After the method was optimized, it was validated in a coated capillary for enantiomeric analysis of tramadol enantiomers in pharmaceutical formulation, including specificity and elution order, linearity, accuracy and precision, determination of limit of detection (LOD) and quantification (LOQ), enantiomeric purity linearity, freedom from interference, and stability of sample solutions. Precision at the target concentration was less than 2%, with an accuracy higher than 99%. Furthermore, the method was able to detect 0.3% and to quantify 1% of the minor enantiomer in the presence of the major one at the target value.
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Affiliation(s)
- S Rudaz
- Istituto di Cromatografia del CNR, Area della Ricerca di Roma, Monterotondo Scalo, Italy
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Wätzig H, Degenhardt M, Kunkel A. Strategies for capillary electrophoresis: method development and validation for pharmaceutical and biological applications. Electrophoresis 1998; 19:2695-752. [PMID: 9870372 DOI: 10.1002/elps.1150191603] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This review is in support of the development of selective, reproducible and validated capillary electrophoretis (CE) methods. Focusing on pharmaceutical and biological applications, the successful use of CE is demonstrated by more than 800 references, mainly from 1994 until 1998. Approximately 80 recent reviews have been catalogued. These articles sum up the existing strategies for method development in CE, especially in the search for generally accepted concepts, but also looking for new, promising reagents and ideas. General strategies for method development were derived not only with regard to selectivity and efficiency, but also with regard to precision, short analysis time, limit of detection, sample pretreatment requirements and validation. Standard buffer recipes, surfactants used in micellar electrokinetic capillary chromatography (MEKC), chiral selectors, useful buffer additives, polymeric separation media, electroosmotic flow (EOF) modifiers, dynamic and permanent coatings, actions to deal with complex matrices and aspects of validation are collected in 20 tables. Detailed schemes for the development of MEKC methods and chiral separations, for optimizing separation efficiency, means of troubleshooting, and other important information for key decisions during method development are given in 19 diagrams. Method development for peptide and protein separations, possibilities to influence the EOF and how to stabilize it, as well as indirect detection are considered in special sections.
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Affiliation(s)
- H Wätzig
- Institut für Pharmazie und Lebensmittelchemie, Würzburg, Germany.
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Abstract
This review presents the different chiral selectors used in capillary electrophoresis (CE) for the separation of enantiomers. The use of charged cyclodextrins, crown ethers, polysaccharides, proteins, natural and synthetic micelles, macrocyclic antibiotics and ergot alkaloids is discussed in detail. Neutral native and derivatized cyclodextrins are not treated because several review articles have already been published on this topic. Recent developments like the application of two chiral selectors in the same background electrolyte are highlighted.
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Affiliation(s)
- K Verleysen
- Department of Organic Chemistry, University of Gent, Belgium
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48
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Systematic approach to methods development for the capillary electrophoretic analysis of a minor enantiomer using a single-isomer sulfated cyclodextrin. J Chromatogr A 1998. [DOI: 10.1016/s0021-9673(98)00385-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Haynes JL, Shamsi SA, O'Keefe F, Darcey R, Warner IM. Cationic beta-cyclodextrin derivative for chiral separations. J Chromatogr A 1998; 803:261-71. [PMID: 9604336 DOI: 10.1016/s0021-9673(97)01212-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A novel hepta-substituted beta-cyclodextrin bearing the methoxyethylamine group linked to the upper cyclodextrin rim was successfully used as a chiral selector for enantiomeric separation of non-steroidal anti-inflammatory drugs (NSAIDs) and phenoxypropionic acid herbicides (PPAHs). Separation parameters such as pH and concentration were found to have major influences on enantiomeric resolution of the NSAIDs and PPAHs. Results indicate that heptakis(6-methoxyethylamine-6-deoxy)-beta-cyclodextrin [beta-CD-OMe (VII)] performs exceptionally well for the enantiomeric resolution of NSAIDs: indoprofen and fenoprofen (Rs = 11 and 14, respectively). In addition, baseline enantiomeric separation of a mixture of six pairs of PPAHs was achieved in under 30 min. Compared to other cationic beta-cyclodextrins reported in the literature, the beta-CD-OMe (VII) showed improved selectivity for both classes of the aforementioned anionic racemates.
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Affiliation(s)
- J L Haynes
- Department of Chemistry, Louisiana State University, Baton Rouge 70820, USA
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50
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Fanali S, Aturki Z, Desiderio C. New strategies for chiral analysis of drugs by capillary electrophoresis. Forensic Sci Int 1998. [DOI: 10.1016/s0379-0738(98)00013-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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