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  • 1
    ISSN: 0935-6304
    Schlagwort(e): Liquid chromatography, LC ; Reversed-phase ; Monomeric and polymeric C18 phases ; Length-to-breadth ratio ; Selectivity ; Structure-retention relationship ; Polycyclic aromatic hydrocarbons (PAH) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reversed-phase liquid chromatography (LC) on C18 stationary phases provides excellent selectivity for the separation of polycyclic aromatic hydrocarbons (PAH). Recent studies have shown that several factors affect selectivity for the LC separation of PAH including phase type (monomeric or polymeric), pore diameter and surface area of the silica substrate, and surface density of the C18 ligands. In this paper the separation of eleven PAH isomers of molecular weight 278 is used to further illustrate the effect of stationary phase characteristics and shape of the solute (length-to-breadth ratio, L/B) on retention and selectivity. Only polymeric C18 phases with a high C18 surface coverage provided separation of all eleven isomers and the elution order of these isomers generally followed increasing L/B values. The effect of solute nonplanarity on reversed-phase LC retention was investigated on both monomeric and polymeric phases using a series of planar and nonplanar PAH pairs. For each solute pair, the nonplanar solute eluted earlier than the planar solute, the largest selectivity factors being observed on the C18 phase with the highest percent carbon load. Based on these studies, a model is proposed to describe the retention of PAH on polymeric C18 phases.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 383-387 
    ISSN: 0935-6304
    Schlagwort(e): Liquid chromatography, HPLC ; Selectivity ; Polycyclic aromatic hydrocarbons, PAH ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An empirical test is described for the evaluation of column selectivity in reversed-phase liquid chromatography. Using a test mixture of three polycyclic aromatic hydrocarbons (PAH), overall column selectivity toward PAH was assessed for over 20 different commercial C18 columns. Retention behavior was correlated to phase type (i.e., monomeric and polymeric surface modification chemistry) for custom synthesized phases. A classification scheme is proposed in which commercial C18 columns are grouped into three classes based on retention behavior: monomeric-like, polymeric-like, and intermediate phase selectivity toward PAH. Correlation of retention behavior of the test mixture with the separation of PAH mixtures and with more general column properties (e.g., phase thickness) is discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1612-1112
    Schlagwort(e): Capillary GC ; Reversed-phase LC ; Liquid crystalline phase ; Selectivity ; Octadecylsilane (C18) phase ; Polycyclic aromatic hydrocarbon (PAH) ; Shape selectivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Octadecylsilane (C18) stationary phases for liquid chromatography (LC), which are prepared by polymeric rather than monomeric phase synthesis, exhibit shape selectivity for isomeric polycyclic aromatic hydrocarbons (PAH) that is similar to the shape selectivity observed for liquid crystalline phases in gas chromatography (GC). Relative retention measurements for several sets of isomeric PAH on a polymeric C18 stationary phase (reversed-phase LC) and liquid-crystalline polysiloxane stationary phase (capillary GC) were compared and correlated with the simple length-to-breadth shape descriptor of the solute. Similar retention behavior was observed for both chromatographic systems. In fact, anomalies in elution order relative to length-to-breadth ratios were generally found to be consistent in both chromatographic systems and could often be ascribed to secondary shape factors (i.e., planarity of the molecule).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1612-1112
    Schlagwort(e): Reversed-phase liquid chromatography ; Polycyclic aromatic hydrocarbons ; Bonded phase synthesis ; n-Decyl bonded phase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The results of a chromatographic comparison of newly synthesized reversed-phase bonded stationary phases incorporating various degrees of unsaturation or rigidity are presented. The phases studied included monomeric n-decyl, polymeric n-decyl, adamantyl, norpinyl, decadiynyl, phenylbutyl and β-naphthyl bonded phases. The effect of bonded phase structure on retention is discussed for selected aromatic solutes.
    Materialart: Digitale Medien
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