In humans the toxic trace element lead (Pb) mainly accumulates in the skeletal tissue where it resides for a long period. Although Pb is known to play a role in bone and cartilage diseases, the distribution of Pb in these tissues is mostly unknown. Therefore synchrotron‐radiation‐induced micro x‐ray fluorescence analysis (SR µ‐XRF) in various geometries was used to determine the distributions of Pb, Ca, Zn and Sr at the cartilage‐bone interface in human femoral heads and patellae. SR µ‐XRF results were matched with backscattered electron (BE) images providing information on structural features of the tissue. Conventional SR µ‐XRF at HASYLAB beamline L showed that Pb mostly accumulates in a zone of some micrometers around the transition between non‐calcified and calcified cartilage. However, the relatively large sample thickness did not allow more precise conclusions. Exploiting the 3D capabilities of confocal SR µ‐XRF and SR microfluorescence tomography at ANKA Fluo‐Topo beamline and HASYLAB beamline L, the spatial resolution could be improved and a highly specific accumulation of Pb at the tidemark, the calcification front between non‐calcified and calcified cartilage, was detected. It was found that Pb and Zn accumulation coincide at the tidemark. Since the tidemark plays an important role in osteoarthritis, the results may strengthen other authors' conclusions that Pb is associated with this joint disease. Although offering less spatial resolution when compared to micro‐tomography, confocal SR µ‐XRF is best suited for such studies. It facilitates the comparison of element maps with other imaging techniques like BE imaging. Copyright © 2007 John Wiley & Sons, Ltd.

The backscatter fundamental parameter (BFP) algorithm was adapted and modified for the use with a portable energy‐dispersive x‐ray fluorescence (EDXRF) spectrometer system. The method utilizes coherently and incoherently scattered peaks of primary radiation to estimate the ‘dark matrix’ of the analysed sample. A so‐called ‘full fundamental parameter’ model was implemented in the algorithm, allowing a simple calibration of the method using only one standard sample. To improve the accuracy of the method, the differential mass scattering cross‐sections were used. The algorithm also takes into account the secondary excitation effects. The method was applied to element determinations in various matrices with minimum sample preparation. It was tested in the laboratory with homogeneous samples prepared from standard reference materials and was also successfully applied to in situ element determinations in soil. The analyses were performed using a portable XRF spectrometer equipped with a 109Cd radioisotope source and an Si‐PIN photodiode detector. The BFP algorithm was found to perform well for the analysis of loose powder samples containing an unknown fraction of ‘dark matrix,’ and therefore it is regarded as suitable for in situ element determinations. Copyright © 2003 John Wiley & Sons, Ltd.

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