Tritiation of Peptides to High Specific Radioactivity. Part 1. Synthesis and Biological Properties of [13-(3H4)Norvaline]-α-MSH and of [2,23-Bis((3H2)tyrosine)]ACTH(1–24)

α-MSH and ACTH(1–24) were tritiated to high specific radioactivity (> 100 Ci/mmol) using a new tritiation apparatus with which the tritiation reaction can be performed at slightly elevated pressure. This allows short reaction times with the least possible damage to the molecule. The starting compounds for the tritiation were 13-propargylglycine]α-MSH and 2,23-Bis(3′,5′-diiodotyrosine)]ACTH(1–24). Both tritiations were quantitative and yielded products of high purity, full biological activity, and with a specific radioactivity of 115 Ci/mmol and 100 Ci/mmol, respectively.