30 years of production of highly enriched nitrogen-15 in the GDR

Almost 30 years ago, the stable isotope ¹⁵N had covered a wide field of application in science and technology. With the preparation of the first smaller amounts of ¹⁵N in 1958, an intensive work of research and development started for the production, analysis, and application of ¹⁵N in the GDR. In this publication, activities of research and development for ¹⁵N production using the principle of chemical exchange in the system NO _x /HNO₃ from a laboratory scale to the introduction into chemical industry are described and new projects reported.