was performed at the Australian Nuclear Science and Technology Organisation (ANSTO) using the 10MV tandem accelerator [44].Samples were analysed using a 3MeV proton beam with a typical spot size between 3 and 5m. At this spot size, beam currents between 0.1 and 0.5 nA can be achieved, which is sufficient for -PIXE analyses. A high-purity Ge detector was used with a 100mm2 active area, located 33mm from the sample. A 100m Mylar foil was used to reduce low energy X-rays and thus pile-up in the-PIXE spectrum. This set-up allowed the detection of the accumulated trace metals such as Ni and Cu with as a high sensitivity as for Au.