The proposal aims to establish the location of the oil, ethyl butyrate in dodecyldimethylamine-N-oxide (DDAO) microemulsions. Molecular dynamic simulations have proposed that a significant amount of the oil forms a core in the centre of the aggregate while drug solubilisation experiments have suggested that the oil forms little or no core, with the majority of the oil being located in the tail region of the surfactant. Small angle neutron scattering together with contrast variation will be used to determine which of the two models is correct. These results will be invaluable in aiding in our understanding of pharmaceutical microemulsions.