Scintillation Counter Assay of I131 and P32 in Blood Volume Studies

Abstract

A well-type Na I crystal scintillation counter is used to obtain simultaneous blood volumes with P32 labelled red cells and with iodinated human serum albumin (I131). Single blood samples are counted in a plastic test tube with and without a brass cup which absorbs most of the beta radiation of the P32 and a small amount of the radiation of the I131. Red cell counts and albumin counts are obtained from the solution of the simultaneous equations Counts without cup = I131 counts + P32 counts Counts with cup = FI I131 counts + Fp P32 counts In vitro and in vivo studies in a 10-kg. dog indicate the near equality of volume distribution of the 2 agents, using the method described.