This proposal is intended to further the measurements required for the full structural investigation of binary alloy FePt nanoparticles (NPs) and the surrounding surfactant layer. We intend to carry out isotopic substitution experiments, utilising the capabilities of the NIMROD beamline. Previous results were promising, but the use of a novel flow-cell system is needed in order to avoid the crystalline diffraction peaks of the solid wax suspension used in the previous experiments. Also, this method will enable the NP-surfactant system to be analysed in its natural state. We will then refine a real space structural model of the NP-surfactant system using this PDF data. The results of which will be immediately publishable, shedding new light on the fundamental properties of nanocrystal systems and their bio-functionality, enabling key applications information technologies and biomedicine.