Titanium-coated silica spheres prepared by self-assembly technique for use as HPLC packing

Titania-coated silica spheres were prepared by a layer-by-layer self-assembly technique for use as a high-performance liquid chromatography packing. This packing has a high surface area of 202.1 m(2)/g, a large pore volume of 0.36 cm(3)/g, and a pore diameter of 7.0 nm. Furthermore, the packing particles exhibit narrow pore size distribution and good pore structure. The chromatographic behavior of the packing was studied under both normal and reversed-phase conditions. Low column pressures were observed. Aromatic isomeric compounds were well separated on the TiO(2)/SiO(2) column under normal phase conditions; pyridine and aniline derivatives were separated on the octadecyl-bonded TiO(2)/SiO(2) (ODT) column, respectively, under reversed-phase conditions, and highly symmetrical peaks were obtained for 15 basic compounds. The chemical stability of the stationary phase was tested with sodium phosphate solution (10 mmol/L, pH = 10) at 25 degrees C and potassium phosphate solution (50 mmol/L, pH = 10) at 50 degrees C.