Immunochemical METHOD FOR DETERMINATION OF A iodothyronine in a biological fluid with 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid or a salt thereof as TBP blocking agent, AND reagent system kit AND TEST MATERIAL FOR USE IN THE METHOD

摘要

An improved immunoassay method, reagent means, test kit, and test device for determining an iodothyronine, e.g., thyroxine (T-4), in a biological fluid, usually serum or plasma, wherein 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (HMS), or a salt thereof, is employed as a blocking agent for the binding of iodothyronines to thyroxine binding protein (TBP). The present invention is particularly advantageous as applied to homogeneous competitive binding iodothyronine immunoassays employing labels which are participants in enzyme-catalyzed reactions. Such labels include enzyme substrates, coenzymes, enzyme inhibitors, enzyme prosthetic groups, and enzymes.