Iodination of placental ferritin for RIA

For purposes of radioimmunoanalytical determination of serum ferritin, conditions for antigen iodination and seperation were searched for, which could provide a satisfactory radiochemical purity and specific activity, high immunoreactivity and stability of the resulting labeled product, necessary for an acceptable expiration of the RIA kit. Two iodination methods (chloramine and conjugation methods) were tested, and a three-step procedure was elaborated for iodination and seperation by gel column chromatography. The iodinated antigen obtained -125I-placental ferritin with IRmax of about 80%, 125I-<8%, specific activity of about 0.6 MBq/μg and stability for the expiration period of 3 to 4 months - is quite satisfactory for the RIA applications. (author) 9 refs.; 4 figs.; 1 tab