Abstract
Bromine treatment for enhancement of the reactivity of thyroxine by ceric-arsenite reaction has greatly simplified the BEI (butanol-extractable iodine) procedure or determination of serum thyroxine by anion exchange chromatography.
In the course of the study to develope a completely automated direct (non-incineration) method for serum thyroxine using the AutoAnalyzer system, it was found that about 10 % of free thyroxine is dialyzed through the cellophane membrane of the dialyzer when alkalinity of the recipient stream is higher than 0.25 N NaOH. Thus, the automated direct dialysis method has been studied. Application of the method on serum samples revealed that protein-bound thyroxine is dissociated and dialyzed just in the form of free thyroxine, and in serum there are undetermined dialyzable substances which react with the ceric-arsenite system other than thyroxine and inorganic iodide. By combination of gel filtration and the direct dialysis method, it has been developed to completely automate the serum thyroxine determination.
