A BAK removal device is constructed as a plug of microparticles of a hydrophilic polymeric gel that displays a hydraulic permeability greater than 0.01 Da. The polymer hydrophilic polymeric gel comprises poly(2-hydroxyethyl methacrylate) (pHEMA). The particles are 2 to 100 μm and the plug has a surface area of 30 mm2 to 2 mm2 and a length of 2 mm to 25 mm and wherein the microparticles of a hydrophilic polymeric gel has a pore radius of 3 to 60 μm.