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  • Articles: DFG German National Licenses  (4)
  • Chemical Engineering  (2)
  • Molar volumes  (1)
  • Parameter robustness  (1)
  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase capacity factors ; Cavity term ; Molar volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase liquid chromatographic capacity factors are well correlated by an equation of the form: $$logk' = (logk')_0 + mV/100 + s\pi ^* + b\beta + a\alpha $$ wheremV/100 measures the cavity term and π*, β, and α are the solvatochromic parameters that measure solute dipolarity/polarizability, hydrogen bond acceptor basicity, and hydrogen bond donor acidity respectively. Liquid molar volume (molecular weight divided by liquid density at 20°C) $$\bar V$$ , and computer-calculated intrinsic (van der Waals) molecular volume, $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{V} _I $$ , are compared as measures of the cavity term in a number of correlations. $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{V} _I $$ leads to more precise correlations as well as to a “cleaner” dissection of the multiple solute/solvent interactions. The opposing exoergic effect of solvent donor/solute acceptor hydrogen bonding, and endoergic cavity term are the main factors influencing HPLC capacity factors.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Reversed-phase liquid chromatography ; Solvatochromic linear solvation energy relationships ; Parameter robustness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention of 32 monocyclic aromatic compounds and 14 polynuclear aromatic hydrocarbons (PAHs) has been studied on four different bonded phases in each of two mobile phases. An additional data set of 21 monocyclic aromatics judiciously chosen for their well-established solvatochromic parameters, 12 PAHs and 12 polychlorinated biphenyls (containing up to 10 chlorines), were studied on a single column. The results indicate that despite the accuracy of the solvatochromic linear solvation energy method for predicting and correlating the octanol/water partition coefficients and water solubilities of these environmentally important materials, the methodology is limited to only certain types of bonded phases. As a corollary to this observation, we caution others that the common practice of estimating log Kow (Kow=octanol-water partition coefficient) based on measurement of the reversed-phase capacity factors should be limited to specific types of columns.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1493-1498 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Racemic leucine can be separated into d- and l-isomers by fractional extraction across microporous hollow fibers. In this extraction, an aqueous solution of the racemate is fed to the lumen of the fibers, and an octanol solution of dodecyl-l-hydroxyproline flows countercurrently outside of the fibers. The interface between feed and extractant is stabilized by filling the pores in the hollow-fiber walls with a cross-linked polyvinylalcohol gel which offers negligible resistance to mass transfer. The extraction with dodecyl-l-hydroxyproline deliberately imitates earlier studies, facilitating comparisons of hollow-fiber extraction with other techniques. The results show that the isomer yield per equipment volume of racemic separation is 100 times greater than that in a continuously rotating extractor, and 1,000 times greater than that in a conventional packed tower.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 946-953 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article demonstrates that even 1% polydispersity in hollow-fiber diameters can increase plate heights by as much as an order of magnitude. The demonstration includes an analytical extension of the Taylor-Aris and the Golay dispersion theories, a numerical solution using the measured polydisperity, and successful predictions of the performance of different hollow-fiber systems over a range of flow rates. All these results show that the effect of polydispersity can dominate column performance, especially in the region where the column efficiency is optimal.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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