Abstract: This invention relates generally to modified porous solid supports and processes for the preparation and use of same. In particular, passivated porous mineral oxide supports are disclosed that are stabilized against leaching under harsh environmental conditions by the application of a thin, protective polymeric coating atop their porous surfaces and that are characterized by a reversible high sorptive capacity substantially unaccompanied by non-specific adsorption of or interaction with biomolecules. Passivation is achieved by the use of a passivation mixture comprising a main monomer, a passivating monomer that is different from the main monomer, and a crosslinking agent, which mixture upon polymerization results in the substantial elimination of the undesirable non-specific interaction between biomolecules and the protective polymeric coating on the surfaces of the mineral oxide matrix.