Abstract

The dioxan precipitation for separating free from antibody-bound hormone in a radioimmunoassay has been applied to human chorionic gonadotrophin (HCG), human growth hormone (HGH), adrenocorticotrophic hormone (ACTH), and insulin and compared with the charcoal-dextran system of separation. The dioxan separation depends on protein concentration. The behaviour of damaged labelled hormone is difficult to assess. Completeness of separation has to be tested in antigen excess. The optimum conditions must be carefully studied for each hormone.