Tritium-labelling of Natural Products

Abstract

THE universally used tritium gas exchange method introduced by Wilzbach is of advantage for tritium labelling of many organic compounds which cannot be labelled by the usual exchange reactions, and for which convenient chemical syntheses are not available^1,2. Many attempts have been made to obtain products of higher specific activity by the use of extra energy sources such as electrical discharges, γ-rays, microwaves, ultraviolet light and also by iodine catalysis². However, the advantages of these methods (far less tritium activity to be handled and shorter duration of reaction) have been offset by the concomitant substantial increase in amounts of radiochemical by-products. Wenzel et al. have shown that exposure of charcoal-adsorbed substances to tritium gas results in products of higher specific activity and less by-products^2–4. Higher specific activities have also been attained by Meshi et al. by tritiation in the presence of different noble metal catalysts⁵. These authors exposed mechanical mixtures (1 : 1) of organic compounds with either palladium or platinum black to 100 mc. tritium for 4–22 days.