Preparation and chromatographic characterization of zirconia modified with dodecylamine-N,N-dimethylenephosphonic acid

摘要

A new zirconia-based stationary phase was prepared for the first time by modified zirconia with dodecylamine-N,N-dimethylenephosphonic acid (DDPA). The adsorption mode that DDPA adsorbed on zirconia with only one phosphonic group was studied by the coloration reaction. The resultant stationary phase (DPZ) has not only long alkyl groups, but also amino group and free phosphoric groups. The chromatographic characterization of the stationary phase was strongly influenced by these polar groups. Despite the lower surface coverage of the DPZ, the capacity factors of polar solutes on DPZ are greater than that on ODS due to the various retention mechanism provided by the polar groups. The free phosphonic group imparts the negative charges to the stationary phase at high pH and blocks most of the Lewis acid sites on the surface of zirconia, so excellent separations were obtained not only for PAHs and amines, but also for phenols. Separations of benzoic acids and positional isomers of dihydroxylbenzene and nitrophenol on DPZ were improved greatly.