Impregnation behaviors of reverse-phase silica materials and C18-silica HPLC columns were studied using di-(2-ethylhexyl)phosphoric acid (HDEHP) as a model extractant. Initially, the adsorption efficiency of the ligand on different types of bulk particles was investigated using various concentration of HDEHP in different composition of methanol/water mixtures based on a batch technique. Subsequently, impregnation of HPLC columns was performed using the dynamic flow-through technique. The experimental data fitted well to the Langmuir model and the adsorption isotherms from the flow-through experiment were used to prepare extraction columns of different ligand densities. Finally, the impregnated columns were characterized and validated through HPLC separation of the lanthanides.