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  • 1
    ISSN: 0935-6304
    Keywords: Enantiomer separation ; mixed chiral selectors ; modified cyclodextrins ; gas chromatography ; PCB ; o,p´-DDD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Columns containing different types of cyclodextrin derivatives have been evaluated for chiral gas chromatographic separation of atropisomeric PCBs, o,p´-DDT and o,p´-DDD. Separation was attempted on columns containing mixed chiral selectors, and the performance of two closely related selectors was also examined. The cyclodextrins were: permethylated-β-CD (PM-β-CD), heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-CD (2,3-M-6-TBDMS-β-CD), heptakis(2,3-di-O-methyl-6-O-tert-hexyldimethylsilyl)-β-CD (2,3-M-6-THDMS-β-CD), and heptakis(2,3-di-O-ethyl-6-O-tert-hexyldimethylsilyl)-β-cyclodextrin (2,3-E-6-THDMS-β-CD). The cyclodextrins were dissolved in OV-1701 or in a dimethylsiloxane/silarylene copolymer containing 5% phenyl in the backbone. The application of mixed chiral selectors led to improved separations, however; at most eleven PCB congeners were separated on a single column. Chiral resolution of o,p´-DDD was achieved. The use of a dimethylsiloxane/silarylene copolymer as a matrix for the cyclodextrins is a promising approach. With such a matrix, blocking of the CD cavities by silicone substituent groups can be avoided, and a reasonable CD solubility can be provided. The selectivity of heptakis(2,3-di-O-ethyl-6-O-tert-hexyldimethylsilyl)-β-CD and heptakis(2,3-di-O-methyl-6-O-tert-hexyldimethylsilyl)-β-CD was quite different, the former selector could separate four congeners, while the latter separated ten congeners.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Ligand exchange chromatography ; Supercritical fluid chromatography ; Selective stationary phases ; Argentation open tubular columns ; Poly(methylpropylthiol)siloxanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(methyl-3-propylthiol)siloxane has been evaluated for use as stationary phase in open tubular columns for gas and supercritical fluid chromatography. Immobilization of the stationary phase was achieved by crosslinking with 2,4,6-trichloro-1,3,5-triazine. The poly(methyl-3-propylthiol)siloxane stationary phase film was in situ oxidized to the disulphide and sulphonic acid forms and both have been evaluated for use in supercritical fluid chromatography. Good selectivity towards polar polycyclic aromatic compounds has been shown. All the modified forms of the stationary phase were loaded with silver ions and were evaluated with regard to ligand exchange chromatography using supercritical fluid carbon dioxide as a mobile phase. The utility of the stationary phase, having sulphonic acid groups loaded with silver ions, has been demonstrated by separation of fatty acid methyl esters according to their unsaturation.
    Type of Medium: Electronic Resource
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