Abstract: The present disclosure describes a field flow fractionator including (1) a top plate assembly including a first non-corrosive material, at least three fluid fittings machined into the first non-corrosive material, a top cavity machined into the first non-corrosive material, and at least one top plate o-ring configured to form a horizontal geometry of a separation channel, (2) a membrane, (3) a bottom plate assembly including a second non-corrosive material, a bottom cavity machined into the second non-corrosive material, a frit configured to be placed into the bottom cavity, and at least one bottom plate o-ring configured to seal the bottom plate assembly to the top plate assembly, such that a top surface of the second non-corrosive material and a top surface of the frit are machined to be coplanar, and (4) where the top plate assembly, the membrane, and the bottom assembly define the separation channel.