[99mTc]Ca-phytate: some colloidal characteristics related to the optimal preparation conditions

Some physico-chemical characteristics of the colloidal radiopharmaceutical [99mTc]Ca-phytate related to optimal preparation conditions have been studied. It is demonstrated that the Ca2+-phytate stoichiometry is 6:1. Two different Ca-phytate colloids seem to be formed, mainly depending on the Ca2+:phytate molar ratio--one of low mycelar size for a 1:1 Ca2+:phytate molar ratio (cmc = 5.10(-5) M), and another one, with a higher mycelar size for a 6:1 molar ratio (cmc = 8.10(-5) M). This last one it probably better for providing a good quality splenic uptake.