101
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Hintermann L. Peak Separation by Adventitious or Added Water in Normal-Phase Chiral HPLC. J Org Chem 2007; 72:9790-3. [DOI: 10.1021/jo7019256] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lukas Hintermann
- Institut für Organische Chemie, RWTH Aachen, Landoltweg 1, D-52074 Aachen, Germany
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102
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Bielejewska A, Duszczyk K, Kulig K, Malawska B, Miśkiewicz M, Leś A, Żukowski J. Influence of the mobile phase composition on chiral recognition of some pyrrolidin-2-ones in the liquid chromatographic system with polysaccharide stationary phases. J Chromatogr A 2007; 1173:52-7. [DOI: 10.1016/j.chroma.2007.09.070] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 09/17/2007] [Accepted: 09/24/2007] [Indexed: 10/22/2022]
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103
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Kasat RB, Wang NHL, Franses EI. Effects of Backbone and Side Chain on the Molecular Environments of Chiral Cavities in Polysaccharide-Based Biopolymers. Biomacromolecules 2007; 8:1676-85. [PMID: 17439279 DOI: 10.1021/bm070006h] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of the backbone and side chain on the molecular environments in the chiral cavities of three commercially important polysaccharide-based chiral sorbents--cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC), amylose tris(3,5-dimethylphenylcarbamate) (ADMPC), and amylose tris[(S)-alpha-methylbenzylcarbamate] (ASMBC)--are studied by attenuated total reflection infrared spectroscopy (ATR-IR), X-ray diffraction (XRD), 13C cross-polarization/magic-angle spinning (CP/MAS) and MAS solid-state NMR, and density functional theory (DFT) modeling. These sorbents are used widely in preparative-scale chiral separations. ATR-IR is used to determine how the H-bonding states of the C=O and NH groups of the polymer depend on the backbone and side chain. The changes in the polymer crystallinity are characterized with XRD. The changes in the polymer helicity and molecular mobility for polymer-coated silica beads (commercially called Chiralcel OD, Chirapak AD, and Chiralpak AS) are probed with 13C CP/MAS and MAS solid-state NMR. The IR wavenumbers and the NMR chemical shifts for the polymer backbone monomers and dimers and the side chains are predicted at the DFT/B3LYP/6-311+g(d,p) level of theory. It is concluded that the molecular environments of the C=O, NH, and phenyl groups show significant differences in intramolecular and intermolecular interactions and in the nanostructures of the chiral cavities of these biopolymers. These results have implications for understanding how the molecular environments of chiral cavities of these polymers affect their molecular recognition mechanisms.
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Affiliation(s)
- Rahul B Kasat
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907-2100, USA
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104
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Wang DX, Zhang XX, Zhang JL, Wang MX. Separation and Recognition of the Enantiomers of trans Arylcyclopropanecarboxylic Acids and their Amide and Nitrile Derivatives on Polysaccharide Stationary Phases. Chromatographia 2007. [DOI: 10.1365/s10337-006-0161-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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105
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Sztojkov-Ivanov A, Tóth D, Szatmári I, Fülöp F, Péter A. High-performance liquid chromatographic enantioseparation of 1-(aminoalkyl)-2-naphthol analogs on polysaccharide-based chiral stationary phases. Chirality 2007; 19:374-9. [PMID: 17380485 DOI: 10.1002/chir.20392] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The enantiomers of various 1-(alpha-aminobenzyl)-2-naphthol and 1-(aminoalkyl)-2-naphthol analogs were separated on cellulose-tris-3,5-dimethylphenyl carbamate-based chiral stationary phases (Chiralcel OD-H and Chiralcel OD-RH), using n-hexane/2-propanol/diethylamine or phosphate buffer/organic modifier mobile phases. The 3,5-dimethylphenyl carbamoylated cellulose columns were effective in both normal and rev ersed-phase modes. The effects of the mobile phase composition, the pH, the buffer concentration, and the structures of the substituents on the 2-naphthol on the enantioseparations were studied. The absolute configuration and elution sequence were determined for 1-(1-amino-2-methylpropyl)-2-naphthol: the elution sequence was S < R.
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Affiliation(s)
- Anita Sztojkov-Ivanov
- Institute of Pharmaceutical Chemistry, University of Szeged, H-6720 Szeged, Eötvös u. 6, Hungary
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106
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Loeser E, Yowell G, Drumm P. Effect of Tertiary Alcohol Additives on Enantioselectivity of the Chiral‐AGP Column. J LIQ CHROMATOGR R T 2006. [DOI: 10.1080/10826070600922953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Eric Loeser
- a Chemical and Analytical Development , Novartis Pharmaceuticals , East Hanover, New Jersey, USA
| | - Guy Yowell
- a Chemical and Analytical Development , Novartis Pharmaceuticals , East Hanover, New Jersey, USA
| | - Patrick Drumm
- a Chemical and Analytical Development , Novartis Pharmaceuticals , East Hanover, New Jersey, USA
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107
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Kasat RB, Zvinevich Y, Hillhouse HW, Thomson KT, Wang NHL, Franses EI. Direct Probing of Sorbent−Solvent Interactions for Amylose Tris(3,5-dimethylphenylcarbamate) Using Infrared Spectroscopy, X-ray Diffraction, Solid-state NMR, and DFT Modeling. J Phys Chem B 2006; 110:14114-22. [PMID: 16854108 DOI: 10.1021/jp061892d] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sorbent-solvent interactions for amylose tris(3, 5-dimethylphenylcarbamate) (ADMPC) with five commonly used solvents, hexane, methanol, ethanol, 2-propanol (IPA), and acetonitrile (ACN), are studied using attenuated total reflection infrared spectroscopy (ATR-IR) of thin sorbent films, X-ray diffraction (XRD) of thin films, (13)C cross polarization/magic angle spinning (CP/MAS) and MAS solid state NMR of polymer-coated silica beads (commercially termed "Chiralpak AD"), and DFT modeling. The ADMPC-polymer-coated silica beads are used commercially for analytical and preparative scale separations of chiral enantiomers. The polymer forms helical rods with intra- and inter-rod hydrogen bonds (H-bonds). There are various nm-sized cavities formed between the polymer side-chains and rods. The changes in the H-bonding states of the C=O and NH groups of the polymer upon absorption of each of the five solvents at 25 degrees C are determined with ATR-IR. The IR wavenumbers, the H-bonding interaction energies, and the H-bonding distances of the polymer side-chains with each of the solvent molecules are predicted using the DFT/B3LYP/6-311+g(d,p) level of theory. The changes in the polymer crystallinity upon absorption of each solvent are characterized with XRD. The changes in the polymer crystallinity and the H-bonding states of C=O groups are also probed with (13)C CP/MAS solid-state NMR. The changes in the polymer side-chain mobility are detected using (13)C MAS solid-state NMR. The H-bonding states of the polymer change upon absorption of each polar solvent and usually result in an increase in the polymer crystallinity and the side-chain mobility. The polymer rods are reorganized upon solvent absorption, and the distance between the rods increases with the increase in the solvent molecular size. These results have implications for understanding the role of the solvent in modifying the structure and behavior of the polymer sorbents.
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Affiliation(s)
- Rahul B Kasat
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, IN 47907-2100, USA
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108
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Sellers JA, Olsen BA, Owens PK, Gavin PF. Determination of the enantiomer and positional isomer impurities in atomoxetine hydrochloride with liquid chromatography using polysaccharide chiral stationary phases. J Pharm Biomed Anal 2006; 41:1088-94. [PMID: 16533585 DOI: 10.1016/j.jpba.2006.01.063] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/25/2006] [Accepted: 01/27/2006] [Indexed: 11/20/2022]
Abstract
A normal-phase isocratic chiral liquid chromatographic method has been developed and validated for atomoxetine hydrochloride. In addition to the S-enantiomer of atomoxetine, the conditions separate both para and meta positional isomers and the phenyl des-methyl analog. Method development strategies included (a) evaluation of polysaccharide-based chiral stationary phases with nonaqueous mobile phases, (b) the use of an octyl stationary phase with a sulfated-beta-cyclodextrin mobile phase additive, and (c) capillary electrophoresis using a single isomer heptakis-6-sulfato-beta-cyclodextrin modifier. All three approaches yielded acceptable conditions for the separation of atomoxetine from related molecules with the former fully validated and the latter two held as alternatives if needed. The final method conditions employing a Chiralcel OD-H column and mobile phase of hexane/IPA/DEA/TFA (85/15/0.15/0.2, v/v/v/v) at 1.0 mL/min have been fully validated with acceptable specificity, linearity, accuracy, repeatability, intermediate precision and quantitation limit.
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Affiliation(s)
- Jane A Sellers
- Analytical Sciences Research & Development, Eli Lilly & Company, Lilly Corporate Center, Indianapolis, IN 46285, USA
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109
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Wang X, Li WZ, Zhao QY, Li YM, Chen LR. Normal-phase HPLC enantioseparation of novel chiral metal tetrahedrane-type clusters on an amylose-based chiral stationary phase. ANAL SCI 2006; 21:125-8. [PMID: 15732471 DOI: 10.2116/analsci.21.125] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the present work, an amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) chiral stationary phase (CSP) was prepared by coating ADMPC on small-particle silica gel. This ADMPC-CSP was for the first time successfully applied to separate a series of novel chiral metal tetrahedrane-type clusters. Furthermore, the influence of a mobile-phase modifier (various alcohols added in the mobile phase), including its concentration and structure, and the structures of the clusters on the chiral separation and retention was investigated. The results suggest that not only the structure and concentration of alcohol in the mobile phase, but also the subtle structural differences in racemate can have a pronounced effect on the enantiomeric separation and retention.
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Affiliation(s)
- Xia Wang
- Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 342 Tianshui Road, Lanzhou 730000, People's Republic of China
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110
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Nogle LM, Mann CW, Watts WL, Zhang Y. Preparative separation and identification of derivatized β-methylphenylalanine enantiomers by chiral SFC, HPLC and NMR for development of new peptide ligand mimetics in drug discovery. J Pharm Biomed Anal 2006; 40:901-9. [PMID: 16239092 DOI: 10.1016/j.jpba.2005.08.034] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2004] [Revised: 08/23/2005] [Accepted: 08/23/2005] [Indexed: 11/17/2022]
Abstract
A direct preparative purification of all four isomers of the unnatural amino acid beta-methylphenylalanine was achieved using supercritical fluid chromatography (SFC) with stacked-injection. Final purification of the Cbz-methyl ester derived isomers was performed on a Daicel Chiralpak AD-H column (20 mm x 250 mm), using 50:50 methanol/ethanol as the organic modifier and resulted in purification of over 3.4 g of material in 6.25 h with >90% total recovery. The absolute stereochemical assignment of the purified amino acids was determined through a combination of chiral HPLC, NMR and optical rotation studies. To our knowledge, this is the first reported preparative approach that has yielded all four compounds in a single chromatographic run.
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Affiliation(s)
- Lisa M Nogle
- Discovery Analytical Chemistry, Chemical and Screening Sciences, Wyeth Research, 500 Arcola Road, Collegeville, PA 19426, USA.
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111
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Cirilli R, Orlando V, Ferretti R, Turchetto L, Silvestri R, De Martino G, La Torre F. Direct HPLC enantioseparation of chiral aptazepine derivatives on coated and immobilized polysaccharide-based chiral stationary phases. Chirality 2006; 18:621-32. [PMID: 16715514 DOI: 10.1002/chir.20298] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The direct HPLC enantioseparation of Mianserin and a series of aptazepine derivatives is accomplished on polysaccharide-based chiral stationary phases (CSPs). The resolutions are performed on the coated-type Chiralcel OD and Chiralpak AD CSPs and on the first commercially available immobilized-type Chiralpak IA CSP, in normal-phase and polar-organic modes. The complete separation of enantiomers of all racemates investigated was successfully achieved under at least one of CSP/eluent combinations employed. Pure alcohols such ethanol or 2-propanol, with a fixed percentage of DEA added, serve as valuable alternatives to the more common n-hexane-based normal-phase eluents in resolution of Mianserin on the AD CSP. In order to study the chiroptical properties of aptazepine derivatives, chromatographic resolutions are carried out at semipreparative scale using Chiralpak AD and Chiralpak IA as CSPs. Nonconventional dichloromethane-based eluents have permitted to expand the chiral resolving ability of the immobilized Chiralpak IA CSP and to perform mg-scale enantioseparations with an analytical-size column. Assignment of the absolute configuration of the separated enantiomers is empirically established by comparing their chiroptical data with those of structurally related Mianserin.
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Affiliation(s)
- Roberto Cirilli
- Istituto Superiore di Sanità, Dipartimento del Farmaco, Rome, Italy.
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112
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Cirilli R, Ferretti R, Gallinella B, La Torre F, La Regina G, Silvestri R. Comparative study between the polysaccharide-based Chiralcel OJ and Chiralcel OD CSPs in chromatographic enantioseparation of imidazole analogues of Fluoxetine and Miconazole. J Sep Sci 2005; 28:627-34. [PMID: 15912731 DOI: 10.1002/jssc.200400102] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The enantiomeric separation of a series of imidazole analogues of Fluoxetine and Miconazole endowed with potent antifungal activity was performed using cellulose tris(4-methylbenzoate) (Chiralcel OJ) and cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD) as chiral stationary phases. Binary mixtures of n-hexane and alcohol as well as pure alcohols (ethanol or 2-propanol) were used as eluents. The enantiomer elution order was monitored by chiroptical detectors based on on-line optical rotation and circular dichroism measurements. For some of the compounds studied very high enantioseparation factor values (alpha > 7) on Chiralcel OJ CSP were observed. In order to study the chiroptical characteristics of the two most biologically active compounds, chromatographic resolutions were carried out on a semipreparative scale. Assignment of the absolute configuration was empirically established by comparing the CD spectra of the separated enantiomers with those obtained from the enantiomers of Miconazole.
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Affiliation(s)
- Roberto Cirilli
- Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299,1-00161 Roma, Italy
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113
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Tatini R, Sadik O, Bernhard S, Abruña H. Direct resolution of chiral ‘pineno’ fused terpyridyl ligands on amylose based chiral stationary phase using long chain alcohol modifiers. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2004.11.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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114
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Abstract
Molecular chirality is a fundamental consideration in drug discovery, one necessary to understand and describe biological targets as well as to design effective pharmaceutical agents. Enantioselective chromatography has played an increasing role not only as an analytical tool for chiral analyses, but also as a preparative technique to obtain pure enantiomers from racemates quickly from a wide diversity of chemical structures. Different enantioselective chromatography techniques are reviewed here, with particular emphasis on the most widespread high performance liquid chromatography (HPLC) and the rapidly emerging supercritical fluid chromatography (SFC) techniques. This review focuses on the dramatic advances in the chiral stationary phases (CSPs) that have made HPLC and SFC indispensable techniques for drug discovery today. In addition, screening strategies for rapid method development and considerations for laboratory-scale preparative separation are discussed and recent achievements are highlighted.
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Affiliation(s)
- Yingru Zhang
- Discovery Analytical Sciences, Pharmaceutical Research Institute, Bristol-Myers Squibb Company, P. O. Box 4000, Princeton, NJ 08648-4000, USA.
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115
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Helmy R, Wang T. Selectivity of amylose tris(3,5-dimethylphenyl-carbamate) chiral stationary phase as a function of its structure altered by changing concentration of ethanol or 2-propanol mobile-phase modifier. J Sep Sci 2005; 28:189-92. [PMID: 15754828 DOI: 10.1002/jssc.200401892] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In a previous publication, solid-state NMR data showed that the structure of Chiralpak AD chiral stationary phase (CSP) was altered by changing the concentration of ethanol or 2-propanol modifier in the chromatographic mobile phase. This present paper reports the effect of the CSP structural change on chiral selectivity alpha. The enantiomers of a series of compounds were chromatographed using ethanol or 2-propanol in various concentrations as mobile-phase modifier and the alpha values were determined. Changes of alpha were observed for some enantiomeric pairs when ethanol and 2-propanol concentrations were varied. These data correlate with previous findings on the structural changes of the CSP. Not every enantiomeric pair showed changes in alpha as the alcohol concentration was varied, indicating that the chiral selectivity depends not only on the CSP's structure, but also on the structures of the analytes.
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Affiliation(s)
- Roy Helmy
- Analytical Research Department, Merck Research Laboratories, Rahway, New Jersey 07065-0900, USA
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116
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Gyllenhaal O, Stefansson M. Reversal of elution order for profen acid enantiomers in packed-column SFC on Chiralpak AD. Chirality 2005; 17:257-65. [PMID: 15844206 DOI: 10.1002/chir.20160] [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: 11/07/2022]
Abstract
Enantiomeric separations of four 2-substituted propionic acid drugs have been studied using packed-column supercritical fluid chromatography (SFC) with amylose tris(3,5-dimethylphenylcarbamate) coated on silica as support (Chiralpak AD). Under standard conditions (i.e., flow rate, 1.5 ml/min; column temperature, 30 degrees C; back-pressure, 150 bar), the order of elution could be reversed when the polar alcohol modifier methanol in carbon dioxide was replaced by 2-propanol for ibuprofen, ketoprofen, and naproxen. For flurbiprofen, with the highest selectivity factor, no reversal was observed, although selectivity was reduced significantly with higher alcohols. Naproxen and flurbiprofen were also investigated with 2-butanol and 2-pentanol. The former showed reversal of elution order but not the latter. For higher alcohol modifiers, including 2-propanol, the peak symmetry was poor but could be improved by addition of citric acid in the alcohol modifier. These results stress the importance to investigate enantiomer elution order during the development of enantioselective methods and when chromatographic conditions are optimized. Preliminary experiments with column temperatures over the range of -15 to 45 degrees C revealed that, in a few cases, reversal took place with a change in temperature only.
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Affiliation(s)
- Olle Gyllenhaal
- Analytical Development, Pharmaceutical and Analytical R & D, AstraZeneca R & D Mölndal, Mölndal, Sweden.
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117
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Wang P, Jiang S, Liu D, Jia G, Wang Q, Wang P, Zhou Z. Effect of alcohols and temperature on the direct chiral resolutions of fipronil, isocarbophos and carfentrazone-ethyl. Biomed Chromatogr 2005; 19:454-8. [PMID: 16037928 DOI: 10.1002/bmc.505] [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: 11/11/2022]
Abstract
The enantiomeric separations of three pesticides fipronil (asymmetric nitrogen), isocarbophos (asymmetric phosphorus) and carfentrazone-ethyl (asymmetric carbon) were studied on cellulose-tri(3,5-dimethylphenylcarbamate) chiral stationary phase using high-performance liquid chromatography under normal phase. The mobile phase was n-hexane with alcohols including ethanol, n-propanol, iso-propanol, n-butanol and iso-butanol as polar modifiers. The flow rate was 1.0 mL/min with UV detection at 280, 225 and 230 nm for fipronil, isocarbophos and carfentrazone-ethyl respectively. The influence of the modifiers and their volume content and temperature from 0 to 50 degrees C on the separations was investigated. The chiral stationary phase showed excellent stereoselectivity for the two enantiomers of fipronil and isocarbophos and certain chiral recognition for carfentrazone-ethyl. Iso-propanol was more suitable for the chiral separation of isocarbophos and carfentrazone-ethyl, and iso-butanol was better for fipronil. The resolutions increased with the decreasing modifier content and temperature for all the three chiral pesticides.
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Affiliation(s)
- Peng Wang
- Department of Applied Chemistry, China Agricultural University, Beijing 100094, People's Republic of China
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118
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Cirilli R, Ferretti R, Gallinella B, Turchetto L, Bolasco A, Secci D, Chimenti P, Pierini M, Fares V, Befani O, La Torre F. Enantiomers of C5-chiral 1-acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives: Analytical and semipreparative HPLC separation, chiroptical properties, absolute configuration, and inhibitory activity against monoamine oxidase. Chirality 2004; 16:625-36. [PMID: 15382204 DOI: 10.1002/chir.20085] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The HPLC enantiomer separation of a novel series of C(5)-chiral 1-acetyl-3-(4-hydroxy- and 2,4-dihydroxyphenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole derivatives, with inhibitory activity against monoamine oxidases (MAO) type A and B, was accomplished using polysaccharide-based chiral stationary phases (CSPs: Chiralpak AD, Chiralcel OD, and Chiralcel OJ). Pure alcohols, such as ethanol and 2-propanol, and typical normal-phase binary mixtures, such as n-hexane and alcohol modifier, were used as mobile phases. Single enantiomers of several analytes examined were isolated on a semipreparative scale, and their chiroptical properties were measured. The assignment of the absolute configuration was established for one compound by single-crystal X-ray diffraction method and for the other three by CD spectroscopy. The inhibitory activity against MAO of racemic samples and single enantiomers were evaluated in vitro.
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Affiliation(s)
- Roberto Cirilli
- Istituto Superiore di Sanità, Dipartimento del Farmaco, Rome, Italy
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