Major and trace elements in mouse bone measured by surface and bulk sensitive methods

Complete text of publication follows. In the past years an increasing research interest turned to the accurate determination of the components of bone samples. These investigations focused on both the major and trace elements in the bone. Work in this field is strongly motivated because various major and trace element concentrations can be good indicators of several diseases. Number of studies also focused on the determination of the components both in the organic and inorganic parts of the bone separately, because they both have role during bone remodeling processes. Also important to note that bone can be one of the final destinations in the body where toxic elements are deposited. In this work we performed various surface and bulk sensitive analyses for the mouse bone samples to determine its major and trace element components. We have shown concentration profiles for various major and observable trace elements of the mouse bone. We found, in accordance with our expectation, that the mostly surface sensitive XPS technique is not suitable to determine the concentration of the trace elements in bone samples. It was also shown that XPS is a valuable tool not only in the determination of the chemical states of the major components of the bone powder but in the quantitative determination of their relative concentrations. Both the major and the trace elements of the bone samples are determined using PIXE and SNMS spectra. Although the information depths are very different for PIXE (a few tens of micrometer) and for XPS analysis (a few nanometers), our present PIXE result, using the bone sample in its original form for the concentration ratio between Ca and P is in excellent agreement with the XPS results using calcinated mouse bone powder. Discrepancy in Ca/Mg ratio (PIXE: 35.7 and XPS: 12.7) maybe due to many factors, which influence this ratio in bone samples. In the case of PIXE we studied native bones and determined composition of the compact bone at outside surface. By XPS method we measured the composition of the calcinated bone powder, a mixture of the compact and trabecular bone. In the compact bone, the ratio between the cells and the extracellular matrix with minerals is less than in the trabecular bone. The most likely explanation that magnesium, which is characteristically situated in the intracellular space, deliberated during the calcination and appeared homogeneously in the bone powder. Further critical analysis of larger data set is in progress and will be published soon. Acknowledgements. The work was supported in part by the Hungarian Scientific Research Fund OTKA Nos. K67873, K72172, K73703 and by cost action No. MP1002. This work was partly carried out as part of the TAMOP-4.2.1.B-10/2/KONV-2010- 0001 project in the framework of the New Hungarian Development Plan.