Quantitative determination of iron

Using the PIXE method, the concentration and spatial distribution of iron were determined.The spatial distribution maps of the iron concentration in 12 samples of human substantia nigra pars compacta. Estimated uncertainties included contributions from the X-ray peak fitting in the GUPIXWIN software, the uncertainty of H-value calibration factors determined experimentally for our setup, the uncertainty in the measurement of the total collected charge, and the potential variability in the local thickness of the 5 mm tissue sections. The detection limit 0.8 ng/mm2 for iron was calculated by the GUPIXWIN software based on spectra from pure Mylar foil, measured on the edge of the sample outside of the substantia nigra tissue.