Preparation of mesopore zirconia-alumina composite and its application to normal HPLC support

Zirconia-alumina composite was prepared as rigid microspheres by means of a sol-gel process. Scan electron micrograph, electron spectroscopy, nitrogen adsorption, and potentiometric titration were used to characterize the zirconia-alumina composite before and after acid etching. After the acid-etching, the specific surface area of the zirconia-alumina composite is about five times larger than that before acid-etching; the molar ratio of Zr/Al and the acidity also increases, while the pore size decreases. The normal-phase chromatographic performance of the zirconia-alumina composite before and after acid etching was studied by using dichloromethane/cyclohexane, chloroform/cyclohexane, ethanol/cyclohexane as mobile phases. After the acid-etching the zirconia-alumina composite exhibited a higher column efficiency and different separation selectivity as compared With that before the acid etching. Basic compounds have a greater retention on the composite after the acid etching.