The primary biological function of albumins is to be fatty acid carriers. The complexation of fatty acids to the albumin is expected to have a strong effect on its adsorption properties. We propose to use neutron reflectometry to probe the surface changes accompanying fatty acid adsorption on the silica (if it occurs) and incorporation of fatty acid into HSA as a function of pH and composition. We will use contrast variation in the fatty acid to discriminate its behaviour from that of the HSA.