“…Coating the silica with metal oxide layer was shown to be one of the most successful strategies in the preparation of chromatographic supports and led to the expansion of application field of RP-LC without loss in separation efficiencies [5][6][7][8][9]. More recently, silica coated with alumina has been presented as a chromatographic support that, in addition to greater chemical stability, results in a lower residual activity in separations by HPLC compared to coating with other metallic oxides [10][11][12][13]. Thus, polar solutes are not retained on the phases of aluminized silica as strongly as they are on silica coated with other metal oxides, such as zirconia [14,15] and titania [14,16].…”