Cellulose cylinders and circular filter papers spiked with known amounts of standard element solutions were prepared for studying
some aspects of assessing measurement uncertainty of NAA and the elemental distribution measured by micro-PIXE analysis. Results
for the cylinders showed strongly non-homogeneous distribution of the elements, both in radial and vertical directions, dominantly
caused by osmosis driven transport of added liquid solution from the centre to the edges. Results for the thin cellulose filter
paper disks exhibited weaker peaking of the standard element concentrations at the edges in comparison with the thick cylinders.