In this work we explore how to use neutron reflection to study the interfacial adsorption from a natural eggshell membrane polypeptide at the oil/water interface. We will then proceed to study how premixed peptide and SDS adsorbed, followed by adsorbing peptide first and then replacing it by progressively adding SDS. The same expt will then be done in the reverse order to check how pre-adsorbed SDS is replaced by the peptide. We expect the ranges of replacing concentrations are different and these differences may well explain the different emulsion stability as often observed in product formulations. Neutron reflection is about the only method that could unravel such fantastic information about molecular adsorption and replacement at the oil-water interface. As the technique is pioneered on Inter and the signals are mostly weak, we request 4 days on Inter.