[en] To improve the recently developed thyroid hormone radioimmunoassay (RIA) kits, a study on immobilization of T₃ antibodies on inner wall of polystyrene tubes has been carried out. Into a series of polystyrene tubes, a constant volume of alkaline glutaraldehyde solution was added to obtain glutaraldehyde coated tubes by self-polymerization. The tubes were then treated with dilute T₃ antibody solution to react the aldehyde residues on the wall-surface with the amino groups in antibodies. Reaction parameters such as temperature, volume of the glutaraldehyde solution, pH, dilution ratio and temperature of the antibody solution, etc. were controlled. After a definite time, the excess antibody solution was decanted, and tubes were washed with plenty of barbital buffer solution. The resulting antibody coated tubes were tested with antigen bindings to verify the validity in RIA use; To the tubes, T₃-¹²⁵I of high specific activity and barbital buffer containing 8-anilino-1-naphthalene sulfonic acid (ANSA) were added and incubated with or without T₃ standard doses at room temperature. Percentage of the antibody bound radioactivity (B) to the total radioactivity (T) was calculated. The average range of B/T(%) under standard T₃ dose of upto 4 ng/ml was 35-55. The results indicated that the antibody coated tubes are applicable for the solid phase T₃ RIA under a cautious control of accuracy keeping relatively long incubation time. However, an increased amount of the immobilized antibody is further desirable to shorten the incubation time and to increase the assay sensitivity. (Author)