The association of copper and zinc to plasma ligands was studied durin
g the rat perinatal period. Analysis was carried out by means of colum
n chromatography (Sephadex G-150) and atomic absorption spectrophotome
try. Levels of copper were low at birth and showed a sharp increase af
ter day 10. This increase was similar to that of ceruloplasmin activit
y as well as its association with copper. Zinc levels, instead, showed
higher levels before birth and decreased slowly toward the adult valu
es. Association of zinc to albumin and associated proteins showed a pa
ttern similar to the decrease in plasma zinc levels.