APPLICATION OF THE COATED CHARCOAL SEPARATION METHOD TO THE RADIOIMMUNOASSAY OF PLASMA CORTICOTROPHIN

Abstract

SUMMARY A radioimmunoassay method for plasma corticotrophin (ACTH) is described. ACTH is extracted from plasma by adsorption to silicic acid powder and subsequent elution by an acetone—acetic acid mixture. ACTH antiserum and 131 I-labelled ACTH are added and the antigen-antibody reaction proceeds for 3 days. Activated charcoal coated with plasma is used to separate antibody-bound and unbound ACTH. Factors affecting the accuracy, sensitivity, and specificity of the assay have been assessed.