Supercritical Fluid Generated Stationary Phases for Liquid Chromatography

A novel method for the preparation of stationary phases has been developed, using a green chemistry approach that avoids the use of problematic organic solvents. By exploiting properties of supercritical carbon dioxide (sc-CO2), such as solvating power and enhanced diffusivity, organosilanes are reacted with surface silanol groups, for a clean, solvent-free preparation of highly efficient silica bonded phases for liquid chromatography (LC), such as octadecylsilica, fluorinated octylsilica and pentafluorophenylpropyl phases (1). Spectroscopic and thermal analysis and chromatographic performance testing are used to characterise the silica bonded phases. This supercritical fluid technology is also applicable to the synthesis of important silica intermediates and even to the preparation of chiral stationary phases.