The retention of benzene derivatives in the normal-phase mode of high-performance liquid chromatography (HPLC) using a binary mobile phase (n-hexane-THF) on aminopropyl silica gel was considered. The possibility of describing the retention of the sorbates by known models was evaluated. It was established that molecular interactions between a sorbate and components of the mobile phase in solution can significantly affect the retention of the sorbates and the character of the dependence of the retention on the concentration of a modifier in the mobile phase. A quantitative description of this dependence was proposed.