Comparison of liquid chromatographic behaviors on N-methylimidazolium functionalized ZrO2/SiO2-4 and N-methylimidazolium functionalized SiO2 stationary phases

A new stationary phase N-methylimidazolium functionalized ZrO2/SiO2-4 (Zr/SilprMim) has been prepared. The chromatographic property of this stationary phase is investigated by ion chromatography (IC) with inorganic and organic anions, and normal phase HPLC with basic compounds and hydroxybenzenes. The effects of pH and the strength of Lewis base of eluent on separation of anions are studied. This new stationary phase is also compared with a N-methylimidazolium functionalized SiO2 stationary phase (SilprMim). The results show that this new stationary phase can be used in analysis of inorganic anions with great prospects. At the same time, successful separations of some organic anions can be obtained by using phosphate buffer solution as mobile phase. This new stationary phase also has a distinct advantage in the separation of basic compounds in normal phase. But due to the presence of Lewis acid sites on the surface of ZrO2/SiO2-4, Lewis bases such as hydroxybenzenes adsorb very strongly on this new stationary phase, and Lewis acid sites can be masked or modified by the eluent that contain Lewis base groups.