A contribution to the description of the retention mechanism of metal chelates during their reversed-phase chromatography

1985 ◽  
Vol 50 (10) ◽  
pp. 2221-2227 ◽  
Author(s):  
František Vláčil ◽  
Věra Hamplová
Keyword(s):  
Mobile Phase ◽  
Volume Fraction ◽  
Reversed Phase ◽  
Metal Chelates ◽  
Retention Mechanism ◽  
Aqueous Mixtures ◽  
Liquid Liquid Extraction ◽  
Bonded Phase ◽  
Binary Mobile Phase ◽  
Phase Liquid

Mercury(II) diethyldithiocarbamate was chromatographed on silica gel with chemically bonded octadecyl groups using aqueous mixtures with methanol, acetonitrile, dioxane, and tetrahydrofuran, respectively, as the mobile phase, and the dependence of logarithm of the capacity ratio (k) on the volume fraction of water in the binary mobile phase was examined. Also, the dependence of k on the liquid-liquid extraction distribution ratio in an aqueous methanol-n-alkane extraction system was investigated for Cu, Co, Ni, Pb, and Hg diethyldithiocarbamates. Both kinds of dependence are linear, which suggests that the retention of the electroneutral metal chelates during the reversed-phase liquid chromatography on a nonpolar chemically bonded phase is due to the solvophobic effect.

scholarly journals Thermodynamic Insights into the Separation of Carotenoids in Reversed-Phase Liquid Chromatography

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Nicola Marchetti ◽  
Pier Paolo Giovannini ◽  
Martina Catani ◽  
Luisa Pasti ◽  
Alberto Cavazzini
Keyword(s):  
Liquid Chromatography ◽  
Stationary Phase ◽  
Mobile Phase ◽  
Reversed Phase ◽  
Retention Mechanism ◽  
Thermodynamic Quantities ◽  
Reversed Phase Liquid Chromatography ◽  
Mobile Phase Composition ◽  
Solute Transfer ◽  
Phase Liquid

The retention mechanism of four major carotenoids, two xanthophylls (i.e., lutein and zeaxanthin) and two carotenes (i.e., lycopene and β-carotene), was investigated in reversed-phase liquid chromatography with the aim of thermodynamic analysis. The experimental variables considered in this study were the composition of mobile phase (MP) and the temperature. Chromatographic elutions were undertaken under linear, isocratic conditions by using a C18 stationary phase, four different MP compositions (by varying the ratio methanol/acetonitrile from 66.5/28.5 to 47.5/47.5 v/v), and column temperatures in the range 283–313 K. Traditional Van’t Hoff analysis has been used to estimate changes of standard enthalpy (ΔH∘) and Gibbs free energy (ΔG∘) associated with the solute transfer from the mobile to the stationary phase at each mobile phase composition. The thermodynamic quantities have been correlated to the structure of investigated carotenoids and their interaction with the octadecyl silica stationary phase.

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