Investigation of silanol activity on the modified silica surfaces using microcalorimetric measurements.

A detailed description of the stationary-bonded phase surface in reversed-phase liquid chromatography (RPLC) is a topic of great interest in separation sciences. For this purpose, the thermal effects connected with solvent adsorption on the series of octadecyl stationary-bonded phases were investigated. Microcalorimetric study of organic solvent heat of immersion of the stationary-phase and chromatographic measurements of the silanol activity were executed. Good correlation between the heat of immersion of different solvents and the residual silanol activity obtained from chromatographic tests of various stationary phases are observed. The present data suggest that measurement of solvent adsorption heat governed by polar interaction with residual silanols may be a useful tool for the determination of silanol activity and surface topography. The present methodology allows determining the access of the solvent molecules to the residual silanols on the chemically bonded phase surface based on silica gel.