101
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Nehmé R, Perrin C, Guerlavais V, Fehrentz JA, Cottet H, Martinez J, Fabre H. Use of coated capillaries for the electrophoretic separation of stereoisomers of a growth hormone secretagogue. Electrophoresis 2009; 30:3772-9. [DOI: 10.1002/elps.200900093] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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102
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Yang Q, Lue A, Qi H, Sun Y, Zhang X, Zhang L. Properties and Bioapplications of Blended Cellulose and Corn Protein Films. Macromol Biosci 2009; 9:849-56. [DOI: 10.1002/mabi.200900008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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103
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Lin PH, Tong SJ, Louis SR, Chang Y, Chen WY. Thermodynamic basis of chiral recognition in a DNA aptamer. Phys Chem Chem Phys 2009; 11:9744-50. [PMID: 19851552 DOI: 10.1039/b907763d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chiral separation is an important issue in pharmaceutical research and industries, because most organic compounds and biological molecules, including many drugs and food additives, are chiral compounds. DNA aptamers are a new group of chiral selectors; however, there still exists deficiencies in the understanding of the molecular basis of their chiral recognition. Herein, a comparative study of the DNA aptamer binding with L-argininamide (L-Arm) and its enantiomer (D-Arm) is investigated by spectroscopic and calorimetric methods. The effect of various experimental conditions such as temperature, pH and salt concentration on the L-Arm and D-Arm binding properties was studied in order to provide information about the chiral recognition mechanism of the DNA aptamer. An isothermal titration calorimetry study reveals that both L-Arm and D-Arm binding with the aptamer are enthalpy driven and entropy cost processes. The protonated amino group of both L-Arm and D-Arm participates in electrostatic interaction and this interaction is stronger for D-Arm than L-Arm binding with the aptamer. From the opposite behavior of the heat capacity change of the two enantiomers, we could suggest that L-Arm and D-Arm bind at different binding sites of the aptamer, resulting in different conformations of the binding complexes. In the binding mechanism, electrostatic interaction provided by the protonated amino group with the aptamer and the conformational change of the nucleic acid upon binding are major processes involved for chiral recognition in the DNA aptamer. This study provides information on chiral separation of D- and L-argininamide by the aptamer, which can be successfully achieved by varying the operation temperature based on the opposite heat capacity dependence of the enantiomers binding with the DNA.
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Affiliation(s)
- Po-Hsun Lin
- Institute of Systems Biology and Bioinformatics, National Central University, Jhong-Li, Taiwan 320, Taiwan
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104
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Lecoeur-Lorin M, Delépée R, Morin P. Simultaneous enantioselective determination of fenamiphos and its two metabolites in soil sample by CE. Electrophoresis 2009; 30:2931-9. [DOI: 10.1002/elps.200800697] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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105
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Zhai Z, Chen Y, Wang YJ, Luo GS. Chiral separation performance of micrometer-sized monodispersed silica spheres with high protein loading. Chirality 2009; 21:760-8. [DOI: 10.1002/chir.20677] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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106
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Ozer H, Kocakaya ŞO, Akgun A, Hoşgören H, Togrul M. The enantiomeric recognition of chiral organic ammonium salts by chiral pyridino-macrocycles bearing aminoalcohol subunits. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/j.tetasy.2009.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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107
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Kirschner DL, Green TK. Separation and sensitive detection of D
-amino acids in biological matrices. J Sep Sci 2009; 32:2305-18. [DOI: 10.1002/jssc.200900101] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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108
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Morin P. [Separation of chiral pharmaceutical drugs by chromatographic and electrophoretic techniques]. ANNALES PHARMACEUTIQUES FRANÇAISES 2009; 67:241-50. [PMID: 19596097 DOI: 10.1016/j.pharma.2009.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 03/16/2009] [Accepted: 03/24/2009] [Indexed: 10/20/2022]
Abstract
SUMMARY A large number of pharmaceutical drugs possess one or more centers of asymmetry giving rise to enantiomers whose pharmacological properties and toxicity are often different. At successive stages of drug discovery, the enantiomers of any chiral molecule must be isolated and analyzed and their enantiomeric purity determined. The electrophoretic and chromatographic techniques have become the most important tools to routinely determine the enantiomeric purity of pharmaceutical molecules. Liquid chromatography (LC) is the most widely used because of the large number of columns marketed, the variety of selectivities available and the ease at which analytical results can be scaled up to the preparative level. In particular, more than 80% of enantioseparations of pharmaceutical molecules are successful with polysaccharide-derivative stationary phases (cellulose, amylose) for multiple system solvents (normal phase, polar organic phase or reverse phase). Complementary selectivities can be achieved more rapidly with other types of stationary phase (glycopeptides, Pirkle, cyclodextrins) but their application is hindered by problems of stability (proteins) or transfer to the preparative scale (cyclodextrins). At the present time, glycopeptide phases offer very promising prospects for the separation of amino acids (and derivatives) and peptide enantiomers. In addition, because of its faster analysis and environmental benefits, supercritical chromatography (SFC) has given rise to renewed interest. Capillary electrophoresis (CE) is an orthogonal technique complementary to chromatographic methods. Its principle involves the formation of diastereoisomer complexes after addition of anionic (HS-beta-CD, HS-gamma-CD CM-beta-CD) or neutral (TM-beta -CD, HP-beta-CD, DM-beta-CD, HP-gamma-CD) cyclodextrins to the running buffer. Compared to LC, CE analyses are cheaper (no chiral column, no solvent, low consumption of chiral selector) and peak efficiencies are higher by one order of magnitude. Furthermore, the mechanism of separation in CE is much simpler to understand and predict. However, the low capacity of CD column prevents its use at the preparative scale and consequently hampers its development as an analytical technique. Today, the increasing number of new drug candidate molecules produced daily, and for which the determination of enantiomeric purity is required before further development, encourages the pharmaceutical industry to seek fast chiral analysis methods based on simple protocols. The speed of analysis is more important than resolution. Thus, screening strategies are implemented with HPLC, SFC and CE including the selection of a limited number of chiral selectors with strong powers of chiral recognition.
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Affiliation(s)
- P Morin
- CNRS UMR 6005, Institut de Chimie Organique et Analytique, Université d'Orléans, 45067 Orléans cedex 2, France.
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109
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Taha EA, Salama NN, Wang S. Micelle enhanced fluorimetric and thin layer chromatography densitometric methods for the determination of (+/-) citalopram and its S-enantiomer escitalopram. ANALYTICAL CHEMISTRY INSIGHTS 2009; 4:1-9. [PMID: 19652757 PMCID: PMC2716673 DOI: 10.4137/aci.s2274] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two sensitive and validated methods were developed for determination of a racemic mixture citalopram and its enantiomer S-(+) escitalopram. The first method was based on direct measurement of the intrinsic fluorescence of escitalopram using sodium dodecyl sulfate as micelle enhancer. This was further applied to determine escitalopram in spiked human plasma, as well as in the presence of common and co-administrated drugs. The second method was TLC densitometric based on various chiral selectors was investigated. The optimum TLC conditions were found to be sensitive and selective for identification and quantitative determination of enantiomeric purity of escitalopram in drug substance and drug products. The method can be useful to investigate adulteration of pure isomer with the cheap racemic form.
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Affiliation(s)
- Elham A Taha
- National Organization for Drug Control and Research (NODCAR), 6-Abu Hazem Street, Pyramids Ave. P.O. Box 29, 35521 Giza, Egypt.
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110
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Wang JY, Xu ZL, Wu P, Yin SJ. Binding constant and transport property of S-Naproxen molecularly imprinted composite membrane. J Memb Sci 2009. [DOI: 10.1016/j.memsci.2009.01.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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111
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Ma S, Shen S, Haddad N, Tang W, Wang J, Lee H, Yee N, Senanayake C, Grinberg N. Chromatographic and spectroscopic studies on the chiral recognition of sulfated β-cyclodextrin as chiral mobile phase additive. J Chromatogr A 2009; 1216:1232-40. [DOI: 10.1016/j.chroma.2008.12.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 12/02/2008] [Accepted: 12/05/2008] [Indexed: 10/21/2022]
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112
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Ngim KK, Gu Z, Catalano T. Characterization and resolution of reversed phase HPLC chromatography failure attributed to sulfobutylether-beta-cyclodextrin in a pharmaceutical sample preparation. J Pharm Biomed Anal 2008; 49:660-9. [PMID: 19179031 DOI: 10.1016/j.jpba.2008.12.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 12/03/2008] [Accepted: 12/11/2008] [Indexed: 10/21/2022]
Abstract
A reversed phase HPLC method developed for a drug product formulation using hydroxypropyl-beta-cyclodextrin (HPCD) was rendered ineffective for analyzing a similar formulation containing sulfobutylether-beta-cyclodextrin (SBECD). The active pharmaceutical ingredient (API) and the majority of its impurities became more strongly retained, eluting as an incoherent conglomerate of peaks. Furthermore, this phenomenon was reproduced in subsequent injections of the API reference standard. Based on HPLC and LC-ESI-MS studies, the chromatography failure was attributed to the accumulation of SBECD on the HPLC column. The subsequent interaction of the API with bound SBECD resulted in the aberrant chromatography. An anion-exchange solid-phase extraction treatment was developed and qualified to selectively remove SBECD from sample solutions, thereby allowing the same HPLC method to be used. The sample treatment procedure exhibited suitable accuracy and precision for quantitating the API and its impurities, and resulted in typical chromatographic profiles.
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Affiliation(s)
- Kenley K Ngim
- Analytical Development, Theravance, Inc., 901 Gateway Blvd., South San Francisco, CA 94080, USA.
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113
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114
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Fakhari AR, Nojavan S, Haghgoo S, Mohammadi A. Development of a stability-indicating CE assay for the determination of amlodipine enantiomers in commercial tablets. Electrophoresis 2008; 29:4583-92. [DOI: 10.1002/elps.200800330] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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115
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Liu Y, Fu X, Ma C, Zhong J, Liao Y, Liu H. Chiral separation of raltitrexed by cyclodextrin-modified micellar electrokinetic chromatography. Anal Bioanal Chem 2008; 393:321-6. [DOI: 10.1007/s00216-008-2444-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 09/29/2008] [Accepted: 09/30/2008] [Indexed: 10/21/2022]
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116
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Laskar DB, Zeng L, Xu R, Kassel DB. Parallel SFC/MS‐MUX screening to assess enantiomeric purity. Chirality 2008; 20:885-95. [DOI: 10.1002/chir.20553] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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117
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Mie A, Ray A, Axelsson BO, Jörntén-Karlsson M, Reimann CT. Terbutaline Enantiomer Separation and Quantification by Complexation and Field Asymmetric Ion Mobility Spectrometry−Tandem Mass Spectrometry. Anal Chem 2008; 80:4133-40. [DOI: 10.1021/ac702262k] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Axel Mie
- Department of Analytical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Analytical Development, AstraZeneca R&D, Loughborough, United Kingdom, and Analytical Development, AstraZeneca R&D, SE-221 87 Lund, Sweden
| | - Andrew Ray
- Department of Analytical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Analytical Development, AstraZeneca R&D, Loughborough, United Kingdom, and Analytical Development, AstraZeneca R&D, SE-221 87 Lund, Sweden
| | - Bengt-Olof Axelsson
- Department of Analytical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Analytical Development, AstraZeneca R&D, Loughborough, United Kingdom, and Analytical Development, AstraZeneca R&D, SE-221 87 Lund, Sweden
| | - Magnus Jörntén-Karlsson
- Department of Analytical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Analytical Development, AstraZeneca R&D, Loughborough, United Kingdom, and Analytical Development, AstraZeneca R&D, SE-221 87 Lund, Sweden
| | - Curt T. Reimann
- Department of Analytical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Analytical Development, AstraZeneca R&D, Loughborough, United Kingdom, and Analytical Development, AstraZeneca R&D, SE-221 87 Lund, Sweden
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118
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A screening study of ChirBase molecular database to explore the expanded chiral pool derived from the application of chiral chromatography. J Pharm Biomed Anal 2008; 46:839-47. [DOI: 10.1016/j.jpba.2007.08.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 07/12/2007] [Accepted: 08/28/2007] [Indexed: 02/07/2023]
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119
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Ghosh A, Dey J. Enantiomeric separations of binaphthyl derivatives by capillary electrophoresis usingN-(2-hydroxydodecyl)-L-threonine as chiral selector: Effect of organic additives. Electrophoresis 2008; 29:1540-7. [DOI: 10.1002/elps.200700638] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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120
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Wang Z, Ouyang J, Baeyens WR. Recent developments of enantioseparation techniques for adrenergic drugs using liquid chromatography and capillary electrophoresis: A review. J Chromatogr B Analyt Technol Biomed Life Sci 2008; 862:1-14. [DOI: 10.1016/j.jchromb.2007.11.034] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/20/2007] [Accepted: 11/23/2007] [Indexed: 10/22/2022]
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121
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Pan J, Zhang S, Yan L, Tai J, Xiao Q, Zou K, Zhou Y, Wu J. Separation of flavanone enantiomers and flavanone glucoside diastereomers from Balanophora involucrata Hook. f. by capillary electrophoresis and reversed-phase high-performance liquid chromatography on a C18 column. J Chromatogr A 2008; 1185:117-29. [PMID: 18291407 DOI: 10.1016/j.chroma.2008.01.049] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2007] [Revised: 12/28/2007] [Accepted: 01/16/2008] [Indexed: 11/30/2022]
Abstract
A pair of flavanone glucoside diastereomers, (2R)- and (2S)-eriodictyol-5-O-beta-d-glucopyranoside (1a, 1b), was successfully separated by RP-C(18) high-performance liquid chromatography from Balanophora involucrata Hook. f. Some other compounds, including a pair of flavanone enantiomers, (2R)- and (2S)-eriodictyol (2a, 2b), and a pair of flavanone glucoside diastereomers, (2R)- and (2S)-eriodictyol-7-O-beta-d-glucopyranoside(3a, 3b), were separated by capillary electrophoresis from the same plant. The absolute configurations at C-2 of 1a and 1b were determined based on their circular dichroism spectra. Enzymatic hydrolysis of 1a and 1b by beta-d-glucosidase afforded (2R)- and (2S)-eriodictyol, respectively, which were used as the authentic standards for co-elution to determine the migration order of the enantiomers, 2a and 2b. We also report the first example of identifying the migration order of 2a and 2b and resolving the separation of 3a and 3b by capillary electrophoresis. In addition, 1a was unambiguously characterized for the first time by NMR spectra.
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Affiliation(s)
- Jianyu Pan
- Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
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122
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Bao Y, Huang J, Li T, Armstrong DW. Evaluation of Pentaproline-Based Chiral Stationary Phase by LC. Chromatographia 2007. [DOI: 10.1365/s10337-007-0438-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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123
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Preinerstorfer B, Lämmerhofer M. Recent accomplishments in the field of enantiomer separation by CEC. Electrophoresis 2007; 28:2527-65. [PMID: 17607806 DOI: 10.1002/elps.200700070] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The present review intends to summarize recent developments in the field of enantioselective separations and analysis by CEC. It covers studies published in English language in common peer-reviewed journals within the period between 2003 and 2006. Both, methods making use of chiral mobile phase additives as well as chiral stationary phases for electrochromatographic enantiomer separations, are reviewed. Achievements that have been made on the various column technologies, such as open-tubular, particle-packed, inorganic, organic and particle-fixed (hybrid-type) monolithic as well as molecularly imprinted polymer phases, are discussed.
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Affiliation(s)
- Beatrix Preinerstorfer
- Christian Doppler Laboratory for Molecular Recognition Materials, Institute of Analytical Chemistry and Food Chemistry, University of Vienna, Vienna, Austria
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124
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Hefnawy MM, Sultan MA, Al-Shehri MM. HPLC separation technique for analysis of bufuralol enantiomers in plasma and pharmaceutical formulations using a vancomycin chiral stationary phase and UV detection. J Chromatogr B Analyt Technol Biomed Life Sci 2007; 856:328-36. [PMID: 17681871 DOI: 10.1016/j.jchromb.2007.06.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2006] [Revised: 06/20/2007] [Accepted: 06/22/2007] [Indexed: 11/19/2022]
Abstract
A sensitive and selective high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of bufuralol enantiomers in plasma and pharmaceutical formulations. Enantiomeric resolution was achieved on a vancomycin macrocyclic antibiotic chiral stationary phase (CSP) known as Chirobiotic V with UV detection set at 254 nm. The polar ionic mobile phase (PIM) consisting of methanol-glacial acetic acid-triethylamine (100:0.015:0.010, v/v/v) has been used at a flow rate of 0.5 ml/min. The method is highly specific where other coformulated compounds did not interfere. The stability of bufuralol enantiomers under different degrees of temperature was also studied. The results showed that the drug is stable for at least 7 days at 70 degrees C. The method was validated for its linearity, accuracy, precision and robustness. An experimental design was used during validation to evaluate method robustness. The calibration curves in plasma were linear over the range of 5-500 ng/ml for each enantiomer with detection limit of 2 ng/ml. The mean relative standard deviation (RSD) of the results of within-day precision and accuracy of the drug were <or=10%. There was no significant difference (p>0.05) between inter- and intra-day studies for each enantiomer which confirmed the reproducibility of the assay method. The mean extraction efficiency for S-(-)- and R-(+)-bufuralol from plasma was in the range 97-102% at 15-400 ng/ml level for each enantiomer. The overall recoveries of bufuralol enantiomers from pharmaceutical formulations was in the range 99.6-102.2% with %RSD ranging from 1.06 to 1.16%. The assay method proved to be suitable as chiral quality control for bufuralol formulations by HPLC and for therapeutic drug monitoring.
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Affiliation(s)
- Mohamed M Hefnawy
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia.
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125
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Kahle KA, Foley JP. Two-chiral-component microemulsion electrokinetic chromatography–chiral surfactant and chiral oil: Part 1. Dibutyl tartrate. Electrophoresis 2007; 28:1723-34. [PMID: 17464962 DOI: 10.1002/elps.200600551] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The first simultaneous use of a chiral surfactant and a chiral oil for microemulsion EKC (MEEKC) is reported. Six stereochemical combinations of dodecoxycarbonylvaline (DDCV: R, S, or racemic, 2.00% w/v), racemic 2-hexanol (1.65% v/v), and dibutyl tartrate (D, L, or racemic, 1.23% v/v) were examined as chiral pseudostationary phases (PSPs) for the separation of six pairs of pharmaceutical enantiomers: pseudoephedrine, ephedrine, N-methyl ephedrine, metoprolol, synephrine, and atenolol. Subtle differences were observed for three chromatographic figures of merit (alpha(enant), alpha(meth), k) among the chiral microemulsions; a moderate difference was observed for efficiency (N) and elution range. Dual-chirality microemulsions provided both the largest and smallest enantioselectivities, due to small positive and negative synergies between the chiral microemulsion components. For the ephedrine family of compounds, dual-chiral microemulsions with surfactant and oil in opposite stereochemical configurations provided higher enantioselectivities than the single-chiral component microemulsion (RXX), whereas dual-chiral microemulsions with surfactant and oil in the same stereochemical configurations provided lower enantioselectivities than RXX. Slight to moderate enantioselective synergies were confirmed using a thermodynamic model. Efficiencies observed with microemulsions comprised of racemic dibutyl tartrate or dibutyl-D-tartrate were significantly higher than those obtained with dibutyl-L-tartrate, with an average difference in plate count of about 25 000. Finally, one two-chiral-component microemulsion (RXS) provided significantly better resolution than the remaining one- and two-chiral-component microemulsions for the ephedrine-based compounds, but only slightly better or equivalent resolution for non-ephedrine compounds.
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Affiliation(s)
- Kimberly A Kahle
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA
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126
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Gübitz G, Schmid MG. Advances in chiral separation using capillary electromigration techniques. Electrophoresis 2007; 28:114-26. [PMID: 17136739 DOI: 10.1002/elps.200600411] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
This review gives an overview of recent developments in CZE, EKC, and CEC covering the literature since the year 2004. Since there appeared a special issue on applications, this review focuses on the progress in electromigration techniques and new methodological developments. New techniques, new chiral selectors as well as new chiral stationary phases for CEC are discussed.
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Affiliation(s)
- Gerald Gübitz
- Department of Pharmaceutical Chemistry, Institute of Pharmaceutical Sciences, Karl-Franzens-University, Graz, Austria.
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127
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Mie A, Jörntén-Karlsson M, Axelsson BO, Ray A, Reimann CT. Enantiomer Separation of Amino Acids by Complexation with Chiral Reference Compounds and High-Field Asymmetric Waveform Ion Mobility Spectrometry: Preliminary Results and Possible Limitations. Anal Chem 2007; 79:2850-8. [PMID: 17326611 DOI: 10.1021/ac0618627] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a new method for separation of enantiomers with high-field asymmetric waveform ion mobility spectrometry (FAIMS), coupled to mass spectrometric detection. Upon addition of an appropriate chiral reference compound to the analyte solution and subsequent ionization of the solution by electrospray ionization, analyte enantiomers formed diastereomeric complexes, which were potentially separable by FAIMS. The methodology being developed is intended to be general, but here amino acid analytes are specifically considered. In the examples presented herein, six pairs of amino acid enantiomers were successfully separated as metal-bound trimeric complexes of the form [MII(L-Ref)2(D/L-A)-H]+, where MII is a divalent metal ion, L-Ref is an amino acid in its L form acting as chiral reference compound, and A is the amino acid analyte. For example, D- and L-tryptophan were separated in FAIMS as [NiII(L-Asn)2(D-Trp)-H]+ and [NiII(L-Asn)2(L-Trp)-H]+. As FAIMS separation typically takes place over a time scale of only a few hundred milliseconds, the presented separation method opens new possibilities for rapid analysis of one analyte enantiomer in the presence of the other enantiomer. Preliminary quantification results are presented, which suggest that fast and sensitive quantitative chiral analyses can be performed with FAIMS. Method limitations are discussed in terms of diverse phenomena, which are not yet understood.
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Affiliation(s)
- Axel Mie
- Department of Analytical Chemistry, Chemical Center, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
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128
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Schmid MG, Koidl J, Wank P, Kargl G, Zöhrer H, Gübitz G. Enantioseparation by ligand-exchange using particle-loaded monoliths: Capillary-LC versus capillary electrochromatography. ACTA ACUST UNITED AC 2007; 70:77-85. [PMID: 16978701 DOI: 10.1016/j.jbbm.2006.06.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Revised: 06/13/2006] [Accepted: 06/27/2006] [Indexed: 10/24/2022]
Abstract
Particle-loaded monoliths containing a polymethacrylamide backbone were prepared by suspending a silica-based chiral phase in the mixture of the monomers followed by in-situ polymerization in the capillary. As chiral selector l-4-hydroxyproline chemically bonded to 3 microm silica particles was used following the separation principle of ligand-exchange. Electrolytes containing Cu(II) ions were used. Amino acid enantiomers were separated by capillary-LC and CEC, whereby the latter showed the better resolution properties. For the chiral separation of alpha-hydroxy acids the EOF was reversed by copolymerizing diallyldimethylammonium chloride instead of vinylsulfonic acid as charge providing agent. Short columns of 6 cm were found to be sufficient in the case of CEC for baseline separations of amino acids with alpha values up to 5.
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Affiliation(s)
- Martin G Schmid
- Institute of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, Karl-Franzens-University, Universitätsplatz 1, A-8010 Graz, Austria.
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129
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Kahle KA, Foley JP. Chiral microemulsion electrokinetic chromatography: Effect of cosurfactant identity on enantioselectivity, methylene selectivity, resolution, and other chromatographic figures of merit. Electrophoresis 2006; 27:4321-33. [PMID: 17075937 DOI: 10.1002/elps.200600261] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The effect of cosurfactant identity on microemulsion size, elution range, retention factor, enantioselectivity, methylene selectivity, efficiency, and resolution in chiral microemulsion formulations was examined. The chiral surfactant dodecoxycarbonylvaline was used in conjunction with the cosurfactants 1-butanol, 1-pentanol, 2-pentanol, 1-hexanol, 2-hexanol, cyclopentanol, and cyclohexanol. The millimolar concentration of cosurfactant was held constant regardless of identity. Ethyl acetate was incorporated as the microemulsion oil core and the buffer utilized was 50 mM phosphate at a pH of 7.0. In general, secondary alcohols improved enantioselectivities and primary alcohols had the opposite effect, with the exception of the 1-butanol. The trends observed varied slightly depending on analyte. Of the six chiral analytes tested, cyclopentanol provided the best enantioselectivity for three, 1-butanol for two compounds, and 2-pentanol for one analyte. The lowest enantioselectivities were achieved with 1-pentanol or 1-hexanol for all compounds. Methylene selectivity was found to decrease with reductions in alcohol chain length. Among equal carbon number alcohols, methylene selectivity was lower for secondary alcohols. Efficiency and resolution values varied with different cosurfactants and depended on analyte identity.
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Affiliation(s)
- Kimberly A Kahle
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA
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130
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Matthijs N, Maftouh M, Vander Heyden Y. Chiral separation strategy in polar organic solvent chromatography and performance comparison with normal-phase liquid and supercritical-fluid chromatography. J Sep Sci 2006; 29:1353-62. [PMID: 16894779 DOI: 10.1002/jssc.200500515] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A strategy, including a rapid screening and several optimisation steps, for the separation of chiral molecules of pharmaceutical interest by polar organic solvent chromatography (POSC), using four polysaccharide-based stationary phases, is proposed and compared with previously reported strategies in normal-phase (NPLC) and supercritical fluid chromatography (SFC). In a first part of this paper, different examples demonstrate the effectiveness of the POSC strategy for fast method development. Optimisation is based on the use of experimental design to map the experimental domain in an efficient way. In the second part, the best screening results, obtained after performance of earlier defined chromatographic screening strategies in NPLC and SFC, are compared to those obtained in POSC. The three techniques show complementary separation results and allowed baseline separation of 23 of 25 compounds. POSC is found to be a very interesting separation mode compared to NPLC, because of the many fast (< 10 min) baseline separations obtained.
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Affiliation(s)
- Nele Matthijs
- Dept. Analytical Chemistry and Pharmaceutical Technology, Pharmaceutical Institute, Vrije Universiteit Brussel, Brussels, Belgium
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131
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Van Eeckhaut A, Michotte Y. Chiral separations by capillary electrophoresis: Recent developments and applications. Electrophoresis 2006; 27:2880-95. [PMID: 16688697 DOI: 10.1002/elps.200500375] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper provides an overview of the different classes of chiral selectors that are used in CE. The main properties of every class are described, together with the mechanism of enantioseparation. Newly introduced selectors are also discussed. Pharmaceutical and biomedical applications published from January 2004 till March 2005 are summarized.
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Affiliation(s)
- Ann Van Eeckhaut
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Pharmaceutical Institute, Vrije Universiteit Brussel, Brussels, Belgium
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132
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Toribio L, del Nozal MJ, Bernal JL, Alonso C, Jiménez JJ. Enantiomeric resolution of bifonazole by supercritical fluid chromatography. J Sep Sci 2006; 29:1373-8. [PMID: 16894781 DOI: 10.1002/jssc.200600014] [Citation(s) in RCA: 16] [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
The enantiomeric separation of bifonazole by supercritical fluid chromatography on Chiralpak AD has been studied. The effect of different modifiers (methanol, ethanol, 2-propanol, and acetonitrile) was examined. Enantioseparation was possible with all of them, but the best results were provided by the alcohol-type ones. The resolution was higher than 5 in all cases. The isoelution temperatures Tiso were calculated from the study of the temperature effect for the different organic modifiers. The value of Tiso was below the working temperature range on using methanol, but above it with ethanol or 2-propanol.
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Affiliation(s)
- Laura Toribio
- Department of Analytical Chemistry, Faculty of Science, University of Valladolid, Valladolid, Spain.
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133
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Abstract
Chiral separation of cetirizine, a second-generation H(1)-antagonist, was studied by CD-mediated CE. Several parameters, including pH, CD type, buffer concentration, type of co-ion, applied voltage and temperature, were investigated. The best conditions for chiral separation were obtained using a 75 mM triethanolamine-phosphate buffer (pH 2.5) containing 0.4 mg/mL heptakis(2,3-diacetyl-6-sulfato)-beta-CD and 10% ACN. Online UV detection was performed at 214 nm, a voltage of 20 kV was applied and the capillary was temperature controlled at 25 degrees C by liquid cooling. Hydrodynamic injection was performed for 1 s. The method was validated for the quantification of levocetirizine in tablets and for enantiomeric purity testing of the drug substance. Selectivity, linearity, LOD and LOQ, precision and accuracy were evaluated for both methods. The amount of levocetirizine dihydrochloride in the commercially available tablets was quantified and was found to be within the specification limits of the claimed amount (5 mg). The amount of distomer in levocetirizine drug substance was found to be 0.87 +/- 0.09% w/w, which is in agreement with the certificate of analysis supplied by the company.
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Affiliation(s)
- Ann Van Eeckhaut
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Pharmaceutical Institute, Vrije Universiteit Brussel, Brussels, Belgium
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134
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Matthijs N, Maftouh M, Heyden YV. Screening approach for chiral separation of pharmaceuticals. J Chromatogr A 2006; 1111:48-61. [PMID: 16483582 DOI: 10.1016/j.chroma.2006.01.106] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 01/22/2006] [Accepted: 01/24/2006] [Indexed: 11/23/2022]
Abstract
The aim of this work is to determine generic screening conditions and an initial simple separation strategy allowing the rapid separation of drug enantiomers in polar organic solvent chromatography (POSC). Four cellulose/amylose-based stationary phases were investigated in detail using two mobile phase basis solvents commonly applied in this mode, i.e. acetonitrile and methanol. Polar mode is interesting for use in purification of enantiomers. In a first step, the parameters potentially influencing the separation, such as addition of an alcohol to the polar organic solvent or the type of mobile phase additive(s), were examined by means of experimental designs. Afterwards, the factors found most important are investigated in more detail. Results showed that the cellulose- and amylose-based stationary phases have very broad and complementary enantiorecognition abilities in the POSC mode. The type of organic solvent for the mobile phase appeared to have a dramatic influence on the quality of the separation. Based on the results, a screening strategy was proposed. Enantioseparation was observed in more than 85% of the tested compounds and analysis times of last eluted peak were usually below 10 min.
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Affiliation(s)
- Nele Matthijs
- Department of Analytical Chemistry and Pharmaceutical Technology, Pharmaceutical Institute, Vrije Universiteit Brussel, VUB, Brussels, Belgium
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135
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Miao H, Rubakhin SS, Scanlan CR, Wang L, Sweedler JV. d-Aspartate as a putative cell-cell signaling molecule in theAplysia californicacentral nervous system. J Neurochem 2006; 97:595-606. [PMID: 16539650 DOI: 10.1111/j.1471-4159.2006.03791.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The content, synthesis and transport of D-aspartate (D-Asp) in the CNS of Aplysia californica is investigated using capillary electrophoresis (CE) with both laser-induced fluorescence and radionuclide detection. Millimolar concentrations of D-Asp are found in various regions of the CNS. In the cerebral ganglion, three adjacent neuronal clusters have reproducibly different D-Asp levels; for example, in the F- and C-clusters, up to 85% of the free Asp is present in the D-form. Heterogeneous distribution of D-Asp is also found in the individual identified neurons tested, including the optical ganglion top-layer neurons, metacerebral cells, R2 neurons, and F-, C- and G-cluster neurons. The F-cluster neurons have the highest percentage of D-Asp (approximately 58% of the total Asp), whereas the lowest value of approximately 8% is found in R2 neurons. In pulse-chase experiments with radiolabeled D-Asp, followed by CE with radionuclide detection, the synthesis of D-Asp from L-aspartate (L-Asp) is confirmed. Is D-Asp in the soma, or is it transported to distantly located release sites? D-Asp is clearly detected in the major nerves of A. californica, including the pleuroabdominal and cerebrobuccal connectives and the anterior tentacular nerves, suggesting it is transported long distances. In addition, both D-Asp and L-Asp are transported in the pleuroabdominal connectives in a colchicine-dependent manner, whereas several other amino acids are not. Finally, d-Asp produces electrophysiological effects similar to those induced by L-Asp. These data are consistent with an active role for D-Asp in cell-to-cell communication.
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Affiliation(s)
- Hai Miao
- Department of Chemistry and the Beckman Institute, University of Illinois at Urbana-Champaign, 61801, USA
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136
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Kahle KA, Foley JP. Chiral microemulsion electrokinetic chromatography with two chiral components: Improved separationsvia synergies between a chiral surfactant and a chiral cosurfactant. Electrophoresis 2006; 27:896-904. [PMID: 16470633 DOI: 10.1002/elps.200500608] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this study, the combination of two chiral components in a microemulsion formulation for the separation of enantiomers via microemulsion EKC (MEEKC) was successfully accomplished. Previous publications of chiral microemulsions have utilized only one chiral entity; the surfactant, cosurfactant, or oil was chiral. This is the first study, to date, of the effects of using two chiral species in a single pseudostationary phase (PSP). The chiral surfactant dodecoxycarbonylvaline (DDCV) was used in conjunction with the chiral cosurfactant S-2-hexanol. Ethyl acetate was incorporated as the oil core of the microemulsion and the buffer was 50 mM phosphate at a pH of 7. Additionally, a microemulsion prepared with racemic 2-hexanol was used for comparison to a previous DDCV microemulsion and as a baseline for the newly formulated dual chiral microemulsion. The efficiencies, resolutions, and enantioselectivities for the S-2-hexanol, racemic 2-hexanol, and original 1-butanol DDCV microemulsions are compared. The hexanol-based PSPs provide improved efficiencies and resolutions. To evaluate the combination of each DDCV enantiomer (R and S) with S-2-hexanol, changes in Gibb's free energy were calculated. A synergistic effect was found when two chiral components were combined to form a microemulsion.
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Affiliation(s)
- Kimberly A Kahle
- Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA
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137
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Erny GL, Cifuentes A. Liquid separation techniques coupled with mass spectrometry for chiral analysis of pharmaceuticals compounds and their metabolites in biological fluids. J Pharm Biomed Anal 2006; 40:509-15. [PMID: 16326060 DOI: 10.1016/j.jpba.2005.10.044] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 10/25/2005] [Accepted: 10/26/2005] [Indexed: 11/17/2022]
Abstract
Determination of the chiral composition of drugs is nowadays a key step in order to determine purity, activity, bioavailability, biodegradation, etc., of pharmaceuticals. In this article, works published for the last 5 years on the analysis of chiral drugs by liquid separation techniques coupled with mass spectrometry are reviewed. Namely, chiral analysis of pharmaceuticals including, e.g., antiinflammatories, antihypertensives, relaxants, etc., by liquid chromatography-mass spectrometry and capillary electrophoresis-mass spectrometry are included. The importance and interest of the analysis of the enantiomers of the active compound and its metabolites in different biological fluids (plasma, urine, cerebrospinal fluid, etc.) are also discussed.
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Affiliation(s)
- G L Erny
- Institute of Industrial Fermentations (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
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138
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Li W, Li S. Molecular Imprinting: A Versatile Tool for Separation, Sensors and Catalysis. OLIGOMERS # POLYMER COMPOSITES # MOLECULAR IMPRINTING 2006. [DOI: 10.1007/12_2006_105] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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139
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Mandrioli R, Raggi MA. Advances in the enantioseparation of second-generation antidepressant drugs by electrodriven methods. Electrophoresis 2006; 27:213-21. [PMID: 16421952 DOI: 10.1002/elps.200500297] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Stereochemistry is steadily increasing in importance in the development of new drugs, and the availability of pure enantiomer drugs can make therapy safer and more efficacious. In particular, almost all second-generation antidepressant drugs possess one or more chiral centres; however, only some of them are administered as single enantiomers. A fundamental part of the quality control of pharmaceutical formulations is the determination of enantiomeric excess and enantiomeric purity; this is also important for the therapeutic drug monitoring of depressed patients. For this purpose, efficient and reliable analytical methods are needed and electrodriven techniques (most of all CE, CEC and MEKC) are very efficient and inexpensive candidates for the role. In this review, the enantioselective electrodriven methods available for the analysis of second-generation antidepressant are presented and discussed. In particular, the following pharmacological classes of antidepressants will be considered: selective serotonin reuptake inhibitors (fluoxetine, citalopram, paroxetine, sertraline); norepinephrine reuptake inhibitors (reboxetine); serotonin and norepinephrine reuptake inhibitors (venlafaxine, milnacipran, duloxetine); and noradrenergic and specific serotonergic antidepressants (mirtazapine).
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Affiliation(s)
- Roberto Mandrioli
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Alma Mater Studiorum- University of Bologna, Bologna, Italy
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140
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Abstract
In this review, an updated view of the different strategies used up to now to enhance the sensitivity of detection in chiral analysis by CE will be provided to the readers. With this aim, it will include a brief description of the fundamentals and most of the recent applications performed in sensitive chiral analysis by CE using offline and online sample treatment techniques (SPE, liquid-liquid extraction, microdialysis, etc.), on-column preconcentration techniques based on electrophoretic principles (ITP, stacking, and sweeping), and alternative detection systems (spectroscopic, spectrometric, and electrochemical) to the widely used UV-Vis absorption detection.
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Affiliation(s)
- Carmen García-Ruiz
- Departamento de Química Analítica, Facultad de Química, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
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141
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Alexander C, Andersson HS, Andersson LI, Ansell RJ, Kirsch N, Nicholls IA, O'Mahony J, Whitcombe MJ. Molecular imprinting science and technology: a survey of the literature for the years up to and including 2003. J Mol Recognit 2006; 19:106-80. [PMID: 16395662 DOI: 10.1002/jmr.760] [Citation(s) in RCA: 776] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Over 1450 references to original papers, reviews and monographs have herein been collected to document the development of molecular imprinting science and technology from the serendipitous discovery of Polyakov in 1931 to recent attempts to implement and understand the principles underlying the technique and its use in a range of application areas. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by papers dealing with fundamental aspects of molecular imprinting and the development of novel polymer formats. Thereafter, literature describing attempts to apply these polymeric materials to a range of application areas is presented.
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Affiliation(s)
- Cameron Alexander
- The School of Pharmacy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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142
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Tmej F, Limbergová Z, Hasal P. Modelling and optimisation of enzymatic separating micro-reactor. Bioprocess Biosyst Eng 2005; 28:123-30. [PMID: 16044284 DOI: 10.1007/s00449-005-0420-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Accepted: 04/04/2005] [Indexed: 12/01/2022]
Abstract
A mathematical model of an enzymatic separating microreactor with the electro-osmotic control of reaction component transport rates is analysed. The micro-reactor is considered in a form of a thin channel filled with a gel containing an immobilised enzyme and an adsorbent where the enzyme reaction, the molecular diffusion, the electro-osmotic flux and the adsorption take place. The substrate inhibited enzyme reaction splitting a non-ionic substrate to two non-ionic products is considered. The reactor operates in a periodic regime, when the channel entry is exposed to the periodic substrate concentration pulses. A chromatographic separation of reaction components, therefore, proceeds in the channel. Effects of principal operational parameters of the reactor system-the reaction channel length, the electric current density, the substrate inlet concentration, the rate of adsorption, and the enzyme activity--on resolution of the products at reactor outlet are analysed. The existence of optimum parameter values (maximising the resolution of reaction products) is shown and a multiparametric optimisation of the reactor performance is accomplished.
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Affiliation(s)
- F Tmej
- Department of Chemical Engineering & Center for Nonlinear Dynamics of Chemical and Biological Systems, Institute of Chemical Technology, Prague, 166 28, Prague 6, Czech Republic
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143
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ten Cate AT, Dankers PYW, Sijbesma RP, Meijer EW. Disulfide Exchange in Hydrogen-Bonded Cyclic Assemblies: Stereochemical Self-Selection by Double Dynamic Chemistry. J Org Chem 2005; 70:5799-803. [PMID: 16018671 DOI: 10.1021/jo0501238] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Stereoselective cyclization of cystine-based bifunctional 2-ureido-4[1H]-pyrimidinone derivatives in CDCl(3) solutions was demonstrated by (1)H NMR spectroscopy. Thiolate-catalyzed disulfide exchange in solution led to the equilibration of different diastereomers of 1. At low concentrations, where formation of cyclic assemblies is the dominant mode of association, the molecules act as their own template. At these concentrations the meso diastereomer is formed preferentially, indicating a higher stability of its cyclic assemblies under the applied conditions, in comparison to the other diastereomers.
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Affiliation(s)
- A Tessa ten Cate
- Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, Post Office Box 513, 5600 MB Eindhoven, The Netherlands
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144
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Mertzman MD, Foley JP. Temperature effects on chiral microemulsion electrokinetic chromatography employing the chiral surfactant dodecoxycarbonylvaline. J Chromatogr A 2005; 1073:181-9. [PMID: 15909521 DOI: 10.1016/j.chroma.2004.10.061] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Dodecoxycarbonylvaline (DDCV) microemulsions (1% and 4%, w/v) were employed to evaluate the retention mechanism of a series of enantiomers over a temperature range of 15-35 degrees C. From the acquired retention data, van't Hoff plots were constructed and enthalpy and entropy of transfer were calculated from the slope and intercept, respectively. Resolution, enantioselectivity, distribution coefficients and Gibb's free energy were also calculated, as well as between enantiomer differences in enthalpy, entropy and Gibb's free energy. Finally, comparisons were made between the microemulsion thermodynamic data and a corresponding set of micellar data. While the 4% DDCV microemulsion did not provide a linear van't Hoff relationship, the 1% DDCV microemulsion was linear over a temperature range of 15-30 degrees C. For the 1% DDCV microemulsion, the enthalpic contribution to retention was consistently favorable (deltaH < 0), whereas the entropic contribution varied from compound to compound. Finally, while the achiral attraction of the analytes was greater for the micellar phase, the microemulsion seemed to provide a suitable difference in entropy (and Gibb's free energy) between enantiomers to achieve chiral discrimination.
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Affiliation(s)
- Melissa D Mertzman
- Department of Chemistry, Drexel University, 32nd and Chestnut Streets, Philadelphia, PA 19104, USA
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145
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Elek J, Mangelings D, Iványi T, Lázár I, Heyden YV. Enantioselective capillary electrophoretic separation of tryptophane- and tyrosine-methylesters in a dual system with a tetra-oxadiaza-crown-ether derivative and a cyclodextrin. J Pharm Biomed Anal 2005; 38:601-8. [PMID: 15967287 DOI: 10.1016/j.jpba.2005.02.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 01/31/2005] [Accepted: 02/01/2005] [Indexed: 11/18/2022]
Abstract
Different dual selector systems containing a cyclodextrin derivative (methyl-beta-cyclodextrin and dimethyl-beta-cyclodextrin) and a new diaza-crown-ether derivative (N-[2-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecan-7-yl)propanoyl]glycine) were studied in the enantioselective separation of tryptophan-methylester and tyrosine-methylester enantiomers. This paper deals with the systematic study of the effects of changing the composition of the background electrolyte on the resolution of the d- and l- forms using an experimental design approach. It was found that the dual systems allowed a better chiral separation of the amino acid derivatives. The experimental design approach also allowed improving the separation compared to the starting conditions (center point of the design), which were adopted from a previous study.
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Affiliation(s)
- János Elek
- Research Group of Homogeneous Catalysis Hungarian Academy of Sciences, University of Debrecen, P.O. Box 7, Debrecen H-4010, Hungary
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146
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147
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Lee KB, Chin CY, Xie Y, Cox GB, Wang NHL. Standing-Wave Design of a Simulated Moving Bed under a Pressure Limit for Enantioseparation of Phenylpropanolamine. Ind Eng Chem Res 2005. [DOI: 10.1021/ie049413p] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ki Bong Lee
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, and Chiral Technologies, Exton, Pennsylvania 19341
| | - Chim Y. Chin
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, and Chiral Technologies, Exton, Pennsylvania 19341
| | - Yi Xie
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, and Chiral Technologies, Exton, Pennsylvania 19341
| | - Geoffrey B. Cox
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, and Chiral Technologies, Exton, Pennsylvania 19341
| | - Nien-Hwa Linda Wang
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, and Chiral Technologies, Exton, Pennsylvania 19341
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148
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Liu Q, Viranga Tillekeratne LM, Kim YW, Kirchhoff JR, Hudson RA. Evaluation of chiral discrimination of highly negatively charged enantiomers by quaternary ammonium β-cyclodextrin using1H NMR. Chirality 2005; 17:570-6. [PMID: 16196023 DOI: 10.1002/chir.20209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The positively charged quaternary ammonium cyclodextrin, QA-beta-CD, was previously used as a chiral selector to achieve baseline resolution of two of the dianionic enantiomers of disodium 3-(p-isothiocyanatophenoxy)-3-(p-isothiocyanatophenyl)propane-1,2-disulfate by capillary electrophoresis. The basis of the chiral discrimination between QA-beta-CD and the enantiomers was investigated by (1)H NMR spectroscopy. COSY and NOESY spectra were used to infer the role that molecular interactions and the stereocenters have upon association of QA-beta-CD with the enantiomers. A parallel two-step complexation model is used to rationalize the NMR and the chiral discrimination observed during separation of the enantiomers.
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Affiliation(s)
- Qinfeng Liu
- Department of Chemistry, College of Arts & Sciences, University of Toledo, Ohio 43606, USA
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149
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Lin X, Zhu C, Hao A. Evaluation of newly synthesized derivative of cyclodextrin for the capillary electrophoretic separation. J Chromatogr A 2004; 1059:181-9. [PMID: 15628140 DOI: 10.1016/j.chroma.2004.10.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A highly water-soluble new cyclodextrin (CD) derivative 2-O-acetonyl-2-O-hydroxypropyl-beta-CD (2-AHP-beta-CD) was synthesized and tested as an effective chiral selector for the capillary zone electrophoretic resolution (Rs) of several basic and acidic analytes. The primary purpose of the research was to explore the capability of the 2-AHP-beta-CD as chiral selectors on comparison with the neutral CDs such as beta-CD, DM-beta-CD and HP-beta-CD. Substitution with 2-O-acetonyl-2-O-hydroxypropyl group at the secondary hydroxyl sites of the CD is aimed at influencing the magnitude and selectivity of analyte-CD interactions. The chiral resolution was strongly influenced by the concentration of the CDs and buffer pH. 2-AHP-beta-CD showed the best enantiomer resolution properties among the tested compounds, while the other CDs showed inferior or no performances at all.
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Affiliation(s)
- Xiuli Lin
- School of Pharmacy, Shandong University, 44 Wenhuaxi Road, Jinan 250012, China
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Liu Q, Inoue T, Kirchhoff JR, Huang C, Tillekeratne LMV, Olmstead K, Hudson RA. Chiral separation of highly negatively charged enantiomers by capillary electrophoresis. J Chromatogr A 2004; 1033:349-56. [PMID: 15088757 DOI: 10.1016/j.chroma.2004.01.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The separation of two highly negatively charged enantiomeric organic disulfates containing two chiral centers was investigated by capillary electrophoresis using cyclodextrin based chiral selectors added to the run buffer. The optimum separation for the enantiomers was achieved in less than 3 min at 25 degrees C with a run buffer of 10 mM glycine pH 2.4 and 5 mM QA-beta-CD, which is a positively charged quaternary ammonium beta-cyclodextrin derivative. The method resulted in baseline resolution, excellent linearity, and highly reproducible migration times allowing facile evaluation of the enantiomeric purity of the individual isomers. Detection limits for the enantiomeric pair were determined to be 0.3 ng/microl (S/N = 3). The nature of the selector-enantiomer interaction and a quantitative measurement of the apparent stability constants that governed chiral discrimination of the enantiomers with QA-beta-CD were also investigated by UV-Vis spectroscopy and electrospray ionization mass spectrometry.
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Affiliation(s)
- Qinfeng Liu
- Department of Chemistry, College ofArts and Sciences, University of Toledo, Toledo, OH 43606, USA
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