Study on the Chromatographic Behavior of Bases on Dodecylamine-N, N-dimethylenephosphonic Acid-Modified Zirconia Stationary Phase

Abstract

A new zirconia-based stationary phase (DPZ) was prepared by modifying zirconia with dodecylamine-N, N-dimethylenephosphonic acid (DDPA). DDPA was adsorbed on zirconia with only one phosphonic group, with the other being free. Besides the hydrophobic interaction provided by nonpolar dodecyl, DPZ also has dipolar interaction, ion-exchange or electrostatic repellent interaction provided by the free phosphonic group and amino group at different conditions. Separation of bases on this stationary phase was achieved with satisfaction owing to the various retention mechanisms. The influence of methanol content, pH value, ion types, and ionic strength of mobile phase are studied in detail.