Florence Barbara Seibert (October 6, 1897 - August 23, 1991) was an American biochemist. She is said to have read biographies of famous scientists as a teenager which inspired her interest in science. She served as an instructor in pathology from 1924-28 at the University of Chicago and was hired as an assistant professor in biochemistry in 1928. At the University of Chicaco she developed a method for purifying the crystalline tuberculin derivative. This purified protein derivative (PPD) was used in the standard TB test. In 1932, she became assistant professor in biochemistry at the University of Pennsylvania at the Henry Phipps Institute and rose through the ranks to full professor and professor emeritus in 1959, when she retired. After her retirement she did volunteer work for many years in cancer research. She was inducted into the National Women's Hall of Fame in 1990. She died in 1991 at the age of 93.