No abstract available

[en] By-products formed in radiation-induced tritium labelling are identified by co-chromatography with authentic samples or by structure prediction using a quantitative structure-retention index relationship. The by-products, formed from labelling of steroids, polynuclear aromatic hydrocarbons, 7-membered heterocyclic ring structures, 1,4-benzodiazepines, 1-haloalkanes, etc. with activated tritium and adsorbed tritium, are shown to be specifically labelled and anticipated products from known chemical reactions. From analyses of the by-products, one can conclude that the hydrogen abstraction by tritium atoms and the substitution by tritium ions are the mechanisms of labelling. Classification of the tritium labelling methods, on the basis of the type of tritium reagent, clearly shows the active role played by tritium atoms and ions in radiation-induced methods. (author)

[en] Mannitol, galacticol and myo-inositol were labelled by a solid state isotope exchange with gaseous tritium. The labelled polyols were prepared with specific activities in the range 740-4440 TBq/mol (20-120 kCi/mol) after purification by HPLC. (author)

No abstract available

[en] An overview is given of the possibilities of ³H NMR in the characterisation of ³H-labelled compounds. This technique gives information on the identity of the tritiated compounds, the position of the tritium, the distribution of the label and even the radiochemical purity of the labelled products. (author)

No abstract available

[en] Published in summary form only

[en] Radioassays with low-energy beta-emitting nuclides in 96-well plastic plates are tedious and frequently inaccurate because of the necessity of quantitatively removing and transferring the contents of each well to scintillation fluid. The authors therefore investigated the possibility of counting these nuclides by directly placing the entire break-apart well (Microelisa) along with the sample into one of four scintillation counting fluids: toluene-PPO-POPOP with or without Protosol, ACS, and FcoLite. Although some of these scintillation fluids fully dissolved the plastic wells and other did not, we found that the presence of the wells did not appreciably interfere with the efficiency of tritium counting. This technique saves considerable time and reduces possible errors in liquid scintillation counting of samples from plastic microtitration plates. (Auth.)

No abstract available

[en] Tritium labelled splenopentine (Arg-Lys-Glu-Val-Tyr-OH) and diacetylsplenopentine (N_α-ac-Arg-N_ε-ac-Lys-Glu-Val-Tyr-OH) were prepared by the catalytic dehalotritiation of the corresponding diiodopeptides obtained by ICl-iodination. Under conditions which proved to be optimal in foregoing model deuterations, a specific radioactivity of about 90% of the theoretical one was achieved. The labelling result was influenced noticeably by a transfer of solvent hydrogen directly to the substrate analogously as found in the dehalodeuterations of simple amino acid derivatives. (author)