Study of the binding of In-114m radiotracer to human serum components by ultrafiltration and chromatography

The chemical speciation of indium in serum was studied. Ultrafiltration was used to investigate the influence of several buffer systems on the binding characteristics of indium in serum and to study the association of indium with transferrin and albumin. This was performed by means of batch incubati on experiments with a In-114m tracer. Different buffer systems were investi gated. A series of bicarbonate, Tris:HCl and HEPES buffers were found to fi t for this purpose. Phosphate buffer was not suitable, as it is capable of disrupting the binding between indium and transferrin. Batch ultrafiltratio n experiments with In-114m incubated solutions of transferrin and albumin s howed that both proteins are capable of binding indium to a high degree. Th ree chromatographic techniques (SEC, AEC, AC) were used to study the differ ent chemically active species of indium in serum. It is concluded that next to transferrin, albumin is also responsible for the binding and transport of indium in serum.