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Thermodynamics Study of Solvent Adsorption on Octadecyl-Modified Silica.

Bocian S, Soukup J, Jandera P, Buszewski B - Chromatographia (2014)

Bottom Line: 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 highest influence of the temperature on solvation process was observed for stationary phases with high surface coverage.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 St, 87-100 Torun, Poland.

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.

No MeSH data available.


Related in: MedlinePlus

Influence of the temperature on the maximum concentration of the adsorbed solvent (Cads): methanol (a) and acetonitrile (b). Data according to results presented in [34]
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Fig1: Influence of the temperature on the maximum concentration of the adsorbed solvent (Cads): methanol (a) and acetonitrile (b). Data according to results presented in [34]

Mentions: The temperature dependences were investigated on five packed octadecyl columns with different coverage densities (from 0.33 up to 3.27 μmol m−2). As seen in Fig. 1, adsorption of both solvents decreases with the temperature in non-linear manner.Fig. 1


Thermodynamics Study of Solvent Adsorption on Octadecyl-Modified Silica.

Bocian S, Soukup J, Jandera P, Buszewski B - Chromatographia (2014)

Influence of the temperature on the maximum concentration of the adsorbed solvent (Cads): methanol (a) and acetonitrile (b). Data according to results presented in [34]
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4281355&req=5

Fig1: Influence of the temperature on the maximum concentration of the adsorbed solvent (Cads): methanol (a) and acetonitrile (b). Data according to results presented in [34]
Mentions: The temperature dependences were investigated on five packed octadecyl columns with different coverage densities (from 0.33 up to 3.27 μmol m−2). As seen in Fig. 1, adsorption of both solvents decreases with the temperature in non-linear manner.Fig. 1

Bottom Line: 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 highest influence of the temperature on solvation process was observed for stationary phases with high surface coverage.

View Article: PubMed Central - PubMed

Affiliation: Department of Environmental Chemistry and Bioanalytics, Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 St, 87-100 Torun, Poland.

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.

No MeSH data available.


Related in: MedlinePlus