Burk joined the Department of Agriculture in 1929 working in the Fixed Nitrogen Research Laboratory.[1] In 1939, he joined the Cancer Institute as a senior chemist. He was head of the cytochemistry laboratory when he retired in 1974. He also taught biochemistry at the Cornell University medical school from 1939 to 1941. He was a research master at George Washington University. Burk was a close friend and co-author with Otto Heinrich Warburg.[3] He was a co-developer of the prototype of the Magnetic Resonance Scanner and a co-discoverer of biotin.[1][4] Burk published more than 250 scientific articles in his lifetime.[5] He later became head of the National Cancer Institute's Cytochemistry Sector in 1938, although he is often mistaken as leading the entire facility.