[Ultrasensitive immunoassay of hormones]

Two methods for ultrasensitive immunoassay of peptide hormones are presented. One is to reduce the nonspecific binding of labeled reactants in two-site immunoassay by transfer of immune complexes containing labeled reactants from one solid phase to another. The other is a novel noncompetitive immunoassay method for small peptides, in which peptides are biotinylated and subsequently measured by two-site assay using anti-peptide antibody and avidin (streptavidin).