Investigation of retention on bare silica using reversed-phase mobile phases at elevated temperatures

The use of unbonded silica as a stationary phase in reversed-phase HPLC is described as a useful alternative to bonded phase columns for polar, lipophilic amines. Using four lipophilic amines, the role of temperature is shown to favorably impact both efficiency and selectivity, which is not universally seen when using bonded phases. As temperature is raised, retention drops on the silica column. The temperature behavior appears to support the hypothesis that retention is dependant upon electrostatic and adsorptive forces.