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  • 1
    Electronic Resource
    Electronic Resource
    Determination of the specific interaction of disubstituted aromatic compounds on hydrous zirconium oxide-loaded porous polymer resin (1996)
    Springer
    Chromatographia 42 (1996), S. 396-400 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrous zirconium oxide ; Porous polymer resin ; Disubstituted phenols ; ortho-Benzoic acid derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A porous polymer resin loaded with hydrous zirconium oxide (Zr-gel) was evaluated as a stationary phase for the liquid chromatographic separation of disubstituted aromatic compounds. The prepared Zr-gel was used to separate disubstituted phenols andortho-substituted benzoic acid derivatives in reversed-phase mode. The retention time of catechol was greater than those of other disubstituted phenols; this implies that the Zr-gel has specificity for the phenolic hydroxyl group. The retention behavior ofortho-substituted benzoic acid derivatives on the Zr-gel was also evaluated in reversedphase mode using buffer. Phthalic acid was specifically retained in the vicinity of pH 6.0, which has been regarded as the equal adsorbic point. Similar behavior was also observed for salicylic acid, although the retention time of salicylic acid was less than that of phthalic acid. It seems that the specific retention behavior of hydrous zirconium oxide is a result of complexation with ligands such as hydroxyl and carboxyl groups. The results of this study have revealed that the retention mechanism of hydrous zirconium oxide is a combination of ion exchange and interaction based on complexation with ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272129
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of the influence of the base material loaded with hydrous zirconium oxide gel on the retention behavior of disubstituted benzoic acids (1996)
    Springer
    Chromatographia 43 (1996), S. 79-81 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrous zirconium oxide ; Porous polymer resin ; Silica gel ; ortho-Benzoic acid derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silica gel loaded with hydrous zirconium oxide (Zr-gel-S) has been prepared and the influence of the base material on the retention behavior ofo-phthalic acid on the hydrous zirconium oxide was evaluated. The retention behavior of the acid on the Zr-gel-S was compared with that on Zr-gel-5, the polymer-based Zr-gel. Comparable retention behavior,i.e. maximum retention in the vicinity of pH 6, which has been regarded as the equal adsorbic point, was observed for both types of Zr-gel, although there was a large difference in the retention times. The difference in retention on the two types of Zr-gel could be ascribed to nature of the base material. The results in this experiments showed, however, that the specific behavior at pH 6 was an essential characteristic of hydrous zirconium oxide and was not related to the influence of the base materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02272826
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of surface states of chemically modified silicas in aqueous acetonitrile and methanol (1991)
    Springer
    Chromatographia 31 (1991), S. 347-350 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically modified silicas ; Surface states ; n-alkylbenzenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The thermodynamic behaviour of n-alkylbenzenes on chemically modified silicas in reversed-phase liquid chromatography has been examined in acetonitrile-water and methanol-water systems. Plots of the thermodynamic parameters obtained against the organic solvent compositions indicate an interesting trend which implies that the surface states of the chemically modified silicas under the two eluent systems are different.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262190
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Syntheses of spherical silica and titania from alkoxides on a laboratory scale (1994)
    Springer
    Chromatographia 38 (1994), S. 291-294 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column packings ; Silica and titania ; Sol-gel method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A process to synthesize silica and titania as spherical packing materials has been investigated on the laboratory scale by the sol-gel method. The silica and titania obtained were tested under normal-phase separation conditions for comparison of their retention characteristics silica witha a commercial. The silica was found to be similar in its retention behaviour to the commercial silica. The titania showed basic properties and strongly retained acidic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269770
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Elution behaviour of anions and cations on a mixed-bed stationary phase of anion and cation exchange resins (1995)
    Springer
    Chromatographia 40 (1995), S. 539-544 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mixed-bed stationary phase ; Anion and cation exchange resins ; Retention mechanism of anions and cations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention mechanism of anions and cations on a mixed-bed column packed with a mixture of strong anion and cation exchange resins has been studied. Organic acids and inorganic anions have showed the same elution behaviour on the mixed-bed column as on a single anion exchange column. In contrast, different elution behaviours for cations have been observed between the mixed-bed column and a single cation exchange column. On the mixed-bed column, cations would be eluted by a mixed retention mechanism. The primary retention mechanism is ion exchange with eluent cation (H+) for all cations. The ion exchange mechanism on the sites occupied by anion exchange groups makes a greater contribution for monovalent cations. A partition mechanism between the stationary phase and mobile phase contributes to the separation of Mg2+ and Ca2+ by forming neutral compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290265
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    Paper (German National Licenses)
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