Abstract: A new zirconia-based stationary phase (DPZ) was prepared by modifying zirconia with dodecylamine-N,N-dimethylenephosphonic acid (DDPA). DDPA adsorbs on zirconia with only one phosphonic group, and another is free. Besides the hydrophobic interaction provided by non-polar dodecyl, DPZ also has dipolar interaction, ion-exchange and electrostatic repellent interaction provided by the free phosphonic group and amino group at different conditions. Separations of bases on this stationary phase were achieved with satisfaction due to the various retention mechanisms. The influences of methanol content, pH value, ion type and ion strength of mobile phase were studied in detail.

Key words: bases , dodecylamine-N,N-dimetheneylphosphonic acid, zirconia