title: Use of an internal sample attenuator in radioimmunoassay. Assay of triiodothyronine (T3) using starch particles containing entrapped charcoal and bismuth oxide in combination with free antibodies.
abstract: A radioimmunoassay for triiodothyronine involving no separate washing or separation steps is described. By using an internal sample attenuator, bismuth oxide, co-immobilized with the sorbent, charcoal, for the non-bound fraction of T3, a system was designed in which a suspension of starch spheres containing the sorbent and the attenuator was added after the immunological reaction had taken place. The particles sedimented and the whole test tube was counted in a gamma-counter. The coefficient of correlation between the results obtained with the present method and those from conventional procedures was 0.993.
mesh_terms: D000327:Adsorption; D000818:Animals; D000906:Antibodies; D001729:Bismuth; D002606:Charcoal; D006801:Humans; D011108:Polymers; D011817:Rabbits; D011863:Radioimmunoassay; D013213:Starch; D014284:Triiodothyronine
chemical_list: D000906:Antibodies; D011108:Polymers; D014284:Triiodothyronine; D002606:Charcoal; D013213:Starch; D001729:Bismuth