Perhaps you are thinking of George de Hevesy (1885-1966), a Hungarian chemist who:
* Pioneered the use of radioactive isotopes as tracers in biological and chemical research. This work earned him the Nobel Prize in Chemistry in 1943.
* Co-discovered the element hafnium in 1923.
* Made significant contributions to the understanding of chemical processes in living organisms.
If you have a different author in mind, please provide more information.