title: Thermodynamics Study of Solvent Adsorption on Octadecyl-Modified Silica.
abstract: Elution and solvation processes in liquid chromatography may be controlled by temperature changes. In the case of solvent adsorption, the temperature influences the amount of adsorbed solvent as well as the enthalpy and entropy of the solvation process. In this work, the thermodynamic parameters of organic solvents used as organic modifiers in the reversed-phase high-performance liquid chromatography elution process were determined. The changes of enthalpy and entropy in a series of chemically bonded stationary phases were measured to determine the effects of the temperature and surface coverage density of octadecyl ligands on the thermodynamic parameters of the solvation. For both the enthalpy and entropy a parabolic trend was observed with the minimum for medium surface coverage. The correlation of solvent adsorption values with the enthalpy of solvation was also investigated. The highest influence of the temperature on solvation process was observed for stationary phases with high surface coverage.
authors.affiliation: Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 St, 87-100 Torun, Poland.
authors.forename: Szymon
authors.initials: S
authors.lastname: Bocian
authors.affiliation: Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 St, 87-100 Torun, Poland ; Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Soukup
authors.affiliation: Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Jandera
authors.affiliation: Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 St, 87-100 Torun, Poland.
authors.forename: Bogusław
authors.initials: B
authors.lastname: Buszewski
keywords: Column liquid chromatography; Enthalpy; Entropy; Solvent adsorption; Temperature influence