Methods and apparatus are disclosed for depleting liquid in a porous solid phase. The liquid is disposed adjacent a porous solid phase and a controlled flow of a pressurized gas is applied to the disposed liquid sufficient to move the liquid through and substantially deplete the liquid from the porous solid phase wherein the controlled flow controls the rate of gas flow or the volume of gas flow. In some embodiments the porous solid phase is a porous membrane or a particle bed or monolithic support.