In situ analyses of gallstone inner layers by external PIXE

External proton induced X-ray emission analyses were carried out to study the elemental profile at different points of two mixed gallstones inner layers. It was observed that ten minor/trace elements namely P, S, Ca, Mn, Fe, Cu, Zn, Br, Rb and Sr were present in the mixed gallstone layers. Among the elements detected, Ca shows the highest concentration whereas Br, Rb and Sr were found only at some points in trace level. Concentrations of Ca and P were observed to be the highest in the core of the gallstones. The presence of high amount of Cu and Zn on the surface of the gallstones, as compared to other layers, may be due to contamination with bile.