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  • 1
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; Polysiloxane-anchored cyclodextrin stationary phases ; Chirasil-Dex ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0935-6304
    Keywords: Enantioselective GC ; Polysiloxane-anchored cyclodextrin stationary phase ; Chirasil-Dex ; Cyclodextrin derivatives dissolved in OV-1701 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: GLC on polysiloxane-anchored permethylated β-cyclodextrin (Chirasil-Dex) has been used to separate the enantiomers of 106 racemates of different classes of compounds ranging from alkanes to highly polar compounds such as underivatized diols and free acids. Chromatographic data are listed and compared with those obtained by GLC on permethylated β-cyclodextrin dissolved in OV-1701.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0935-6304
    Keywords: Enantioselective capillary gas chromatography ; Enantiomer separation of volatiles ; Cyclodextrin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-resolution capillary gas chromatographic separation of enantiomers, belonging to different classes of compounds on cyclodextrin derivatives is described. The solutions of heptakis (2,3,6-O-trimethyl)-β-cyclodextrin (Phase I), heptakis (2,6-O-dimethyl-3-O-trifluoro-acetyl)-β-cyclodextrin (Phase II) and heptakis (2,6-O-dimethyl-3-O-heptafluorobutyryl)-β-cyclodextrin (Phase III) in the moderately polar polysiioxane OV-1701 were coated onto deactivated fused silica capillaries furnishing columns of high efficiency. The three phases show different enantioselectivities for various racemic mixtures.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 215-223 
    ISSN: 0935-6304
    Keywords: Enantioselective capillary (open-tubular) SFC ; Polysiloxane-anchored cyclodextrin stationary phase ; Immobilized Chirasil-Dex ; Separation of cyclodextrin derivatives by SFC ; Non-steroidal anti-inflammatory drugs (NSAIDs) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Immobilized polysiloxane-anchored permethyl-β-cyclodextrin (Chirasil-Dex) with a cyclodextrin content of approximately 30 % by weight, previously employed as a versatile chiral stationary phase for the separation of enantiomers by GC, has been used for the separation of enantiomers by capillary supercritical fluid chromatography (SFC). A considerable number of racemates could be resolved, e.g. aromatic alcohols, amino alcohols (TFA derivatives), and underivatized acids. Many pharmaceutical compounds were among those analyzed, including several NSAIDs (e.g. ibuprofen and ketoprofen), a steroidal drug (nor-gestrel), a barbiturate (hexobarbital), and others.Among the racemates resolved were many which cannot be analyzed by GC owing to low volatility or decomposition at elevated temperatures. For two racemates, analysis temperature and mobile phase density were systematically varied to give constant analysis times or capacity factors k. Low temperatures (ca 60 °C) yielded the best separation in term of separation factor, α, or resolution, Rs, even though higher densities had to be used. In comparison with GC, capillary SFC was able to furnish higher separation factors and similar resolution. The applicability of capillary SFC for the analysis of mixtures of cyclodextrin derivatives, e.g. those used in the synthesis of Chirasil-Dex, was, furthermore, demonstrated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 289-298 
    ISSN: 0935-6304
    Keywords: Enantioselective GC ; Polysiloxane-anchored cyclodextrin stationary phase ; Chirasil-Dex-TFA ; Immobilized 2,6-di-O-alkyl-3-O-acyl-cyclodextrin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heptakis(2,6-di-O-methyl-3-O-trifluoroacetyl)-†-cyclodextrin has been chemically bonded to a polydimethylsiloxane via an octamethylene spacer and subsequently immobilized on to the surface of fused silica capillaries, the first time a cyclodextrin derivative with mixed substituents has been immobilized in this way. The enantioselectivity of the new chiral stationary phase has been investigated as a function of the cyclodextrin content. It was found to be higher than that reported for heptakis (2,6-di-O-methyl-3-O-trifluoroacetyl)-†-cyclodextrin or hepta-kis(2,6-di-O-methyl-3-O-acetyl)-†-cyclodextrin dissolved in polysiloxane (e.g. OV-1701). The degree of immobilization was over 90 %. The temperature stability is, however, inferior to that of Chirasil-Dex (a permethylated cyclodextrin): the maximum operating temperature is approximately 200 °C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 23-28 
    ISSN: 1040-7685
    Keywords: enantioselectivity ; immobilized permethyl-β-cyclodextrin ; capillary supercritical fluid chromatography ; gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Immobilized permethyl-β-cyclodextrin was used for enantiomer separation by capillary supercritical fluid chromatography and gas chromatography. The influences of pressure and temperature on chiral separation factors, α, and capacity factors, k, have been studied for four representative racemic solutes. The enantioselectivities in supercritical fluid chromatography and gas chromatography are compared. Solvation effects by supercritical carbon dioxide are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 11-22 
    ISSN: 1040-7685
    Keywords: enantioselective gas chromatography ; immobilized permethyl-β-cyclodextrin ; Chirasil-Dex ; permethylated β-cyclodextrin dissolved in OV-1701 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polysiloxane-anchored permethylated β-cyclodextrin (Chirasil-Dex) was used for enantiomeric separation by GC. Four types of Chirasil-Dex, containing up to 36% permethylated β-cyclodextrin by weight, were synthesized and compared with 10% permethylated β-cyclodextrin dissolved in OV-1701. The influence of the cyclodextrin weight percentage on the chiral separation factor α and on polarity, as expressed by the Kovats indices, was studied. The chiral separation factors α did not increase significantly above a threshold of ˜30% permethylated β-cyclodextrin by weight. The plots of α vs. weight percentage depend on the complexation strength of the chiral solutes, as do the Kovats indices; for weakly complexing solutes, changes in the cyclodextrin concentration result in larger changes in α, but in less pronounced changes in the Kovats indices, as compared to strongly complexing solutes. Column performances were investigated for immobilized and nonimmobilized stationary phases. As expected, immobilization properties were found to depend on the content of Si-H groups in the polysiloxane backbone. Immobilized columns exhibited a much better long-term stability of all chromatographic variables investigated.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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