Paul Karrer, 1889–1971, Swiss organic chemist, Ph.D. Univ. of Zürich, 1911. From 1912 to 1918, Karrer was a chemist at the Georg Speyer Haus, Frankfurt-am-Main. He left in 1919 to become professor of chemistry and director of the Chemical Institute at the Univ. of Zürich, where he remained until his retirement in 1953. Karrer won the 1937 Nobel Prize in Chemistry with Norman Haworth for his investigations on carotenoids, flavins, and vitamins A and B2. Karrer is credited with being the first to isolate vitamins A and K and to synthesize vitamins B2 and E. His most significant accomplishment was elucidating the structure of carotene, the yellow pigment found in carrots and other orange and yellow vegetables.