Radioimmunological determination of total thyroxin by antibodies immobilized on polystyrene tubes coated with styrene-maleic anhydride copolymers.

In this new technique for preparing activated polystyrene tubes for assay of human thyroxin (T4) we coated plastic with styrene-maleic anhydride copolymers. The quantity of antibodies immobilized on these tubes was considerably greater than on non-activated polystyrene tubes, and the time required for immobilization was shortened. Calibration curves were plotted, and determination of total T4 in 200 serum samples confirmed the expected increase in sensitivity as compared with a commercial (Gammacoat) method. The manufacturing procedure is simple and could easily be automated. Thus, such copolymer-coated tubes constitute an advantageous and reliable component in the assay of total T4 that can be used to improve the sensitivity of this and various other radioimmunological determinations.