Neutron activation analysis does in principle not
require extensive sample preparation, but as in any bulk
analysis, homogenization is a prerequisite. Sample
preparation followed the same procedure for every
sample. About 50 g (or more, if available) of the rock
salt sample was crushed with exclusively polyethylene
(PE) tools to avoid any contamination by abraded metal
particles. Homogenization by grinding in an agate
mortar to grain sizes o3 mm was followed by drying
to constant weight at 110 1C.