polytetrafluoroethylene (PTFE) (0.2 μm, 25 mm; Merck Millipore Ltd., Ireland), and Strat-M polyethersulfone (PES) (25 mm; Millipore). Binding of HCA was investigated on the five membranes. Each membrane was immersed in 10 mL of the test solution containing 200 μg/mL of HCA in the receptor medium of ethanol and water (55/45