George B. Walden

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George B. Walden (February 18, 1895 – August 6, 1982) was an American chemist who helped Eli Lilly and Company mass-produce insulin. Born in Indiana, he joined Lilly in 1917 and became head chemist in 1922. Walden discovered isoelectric precipitation, a method that uses pH changes to make insulin precipitate while impurities stay dissolved. This yielded insulin that was 10 to 100 times purer than before, solving a major purification problem and making large-scale production possible. The University of Toronto team had turned to Lilly for help with purification, and Walden led the effort.