ABSTRACT
In 1971, Schmit et al. first described the separation of polycyclic aromatic hydrocarbons (PAH) by liquid chromatography (LC) using a chemically bonded octadecylsilane (C18) stationary phase. In addition to the environmental interest in the separation of PAH by LC, PAH have been used extensively as solutes in the investigation of reversed-phase LC retention mechanisms. The chromatographic properties of bonded-phase sorbents are dependent on the conditions of synthesis and the physical and chemical properties of the underlying silica substrate. Monomeric stationary phases result from the reaction of monofunctional silanes with silanols on the silica surface. At high silane concentrations, increases in surface coverage fall off rapidly so that only fractional increases occur even with large excesses of silane. Polymeric phases are synthesized by intentionally introducing a measured quantity of water into a synthesis involving polyfunctional silanes.
