The application of the ceric sulphate-arsenious acid reaction to the detection of thyroxine and related substances

Abstract

During a study of the urinary excretion products in connexion with the clinical trials of the antithy- roxine compound, butyl 4-hydroxy-3:5-diiodobenzoate Although a trace of iodide was present, this reagent could not be used for its quantitative estimation because the principal metabolic product, 4-hydroxy-3:5-diiodobenzoic acid, appeared to catalyse the reduction of ceric sulphate by arsenious acid almost as effectively as iodide. Subsequently it was found that many diiodophenols, including thyroxine and diiodotyrosine, gave similar reactions, and it seemed possible that, with the employment of this reagent, a highly sensitive method for the detection of thyroxine and related substances might be developed.