Otto Folin in biochemistry lab at McLean Hospital, 1905; photo by A.H. Folsom (Harvard)
April 4, 1867|
Åseda, Småland, Sweden
|Died||October 23, 1934(aged 67)|
|Alma mater||University of Minnesota
University of Chicago
|Doctoral advisor||Albrecht Kossel|
|Doctoral students||Edward Adelbert Doisy
George H. Hitchings
James Batcheller Sumner
Otto Knut Olof Folin (April 4, 1867 – October 25, 1934) was a Swedish-born American chemist who is best known for his groundbreaking work at Harvard University on practical micromethods for the determination of the constituents of protein-free blood filtrates and the discovery of creatine phosphate in muscles. 
Folin was born in Åseda, Småland in Sweden. He was the seventh of twelve children of Nils Magnus Folin and Eva Olson. He moved to America at the age of fifteen following two brothers and an aunt who had already settled there. He carried on his schooling in Stillwater, Minnesota. He moved to Minneapolis, Minnesota entering the University of Minnesota and completed his B.S in 1892. 
In 1896, Folin returned to Sweden and began his research in the laboratory of Prof. Olof Hammarsten (1841-1932) at Uppsala University. In 1897, he left to work in the laboratory of the chemist, Ernst Leopold Salkowski at the Pathological Institute of Charité (Charité - Universitätsmedizin Berlin) in Berlin, Germany. In 1890, he became a citizen of the United States. He joined the University of Chicago gaining his Ph.D. in 1898.  
In 1899 he was appointed assistant professor at West Virginia University. He moved to the McLean Hospital Boston in 1900 as a research biochemist, eventually moving to Harvard Medical School in 1907 as an associate professor of biological chemistry, becoming the Hamilton Kuhn Professor of Biological Chemistry and Molecular Pharmacology in 1909. Together with Vintilă Ciocâlteu Otto Folin designed the Folin-Ciocalteu reagent to detect polyphenols. In 1920, he co-developed with Hsien Wu the Folin-Wu method of assaying glucose in protein-free filtrates of blood.
Folin was elected the president of the American Society of Biological Chemists (now the American Society for Biochemistry and Molecular Biology) in 1909. He was a member of the editorial board of the Journal of Biological Chemistry. He was elected to the National Academy of Sciences and was awarded the Carl Wilhelm Scheele Medal of the Swedish Chemical Society in 1930. 
- Approximately complete analyses of thirty "normal" urines (1905)
- Chemical problems in hospital practice (1908)
- Nitrogen retention in the blood in experimental acute nephritis in the cat (1912)
- Preservatives and other chemicals in foods: Their use and abuse (1914)
- On the determination of creatinine and creatine in urine (1914)
- Recent biochemical investigations on blood and urine;: Their bearing on clinical and experimental medicine (1917)
- A System of Blood Analysis by Folin and Wu (1919)
- Laboratory Manual of Biological Chemistry with Supplement (1925)
- "Otto Folin’s Medica Legacy" (PDF). Clin. Chem. 31/8, 1402-1404 (1985). Retrieved November 3, 2015.
- Phillip Anderson Shaffer. "Otto Folin 1867—1934, A Biographical Memoir" (PDF). National Academy of Sciences. Retrieved November 3, 2015.
- "Olof Hammarsten". Svensk biografisk handbok. 1925. Retrieved November 3, 2015.
- Frank H. Wians, Jr, PhD. "Luminaries in Laboratory Medicine: Otto Folin". American Society for Clinical Pathology. Retrieved November 3, 2015.
- Otto Folin's Decade in Minnesota 1882-1892 A Brief Review (Meites, Samuel. Clinical Chemistry, volume 28, issue 10, pages 2173–2177. 1982) Clinical chemistry, Vol 28, No 10, 1982
- Analytical Biochemistry: the Work of Otto Knuf Olof Folin on Blood Analysis (American Society for Biochemistry and Molecular Biology)
- "ASBMB Past Presidents. 1909 – Otto K. O. Folin". American Society of Biological Chemists. Retrieved November 3, 2015.
- Schaffer, Phillip Otto Folin: (1867–1934) (Journal of Nutrition. volume 52, issue 1, pages 3–11. 1954) 
- Edsall, John T. A Biomedical Pioneer: Otto Folin (Science 12 May 1989:Vol. 244. no. 4905, pp. 719 - 720) 
- Meites, Samuel (1989) Otto Folin, America's First Clinical Biochemist (American Association for Clinical Chemistry, Inc., Washington, D.C.) ISBN 978-0915274482