Born Jan. 9, 1868, in Havrebjerg; died Feb. 12, 1939, in Copenhagen. Danish physical chemist and biochemist. Member of the Royal Danish Academy of Sciences and Letters.
Sørensen graduated from the University of Copenhagen. In the years 1892-1901 he was on the research staff of the chemical laboratory of the Technical University of Denmark in Copenhagen. From 1901 to 1938 he was director of the chemistry division at the Carlsberg Laboratory, near Copenhagen.
Sørensen developed one of the basic methods of amino-acid synthesis and a method of quantitatively determining nitrogen in amines. He introduced the concept of pH and developed standard solutions for preparing buffer mixtures with known pH. His studies on the nature of protein solutions as systems of reversibly dissociating components are well known, as are his studies on lipid-protein complexes, the isoionic point of proteins, the osmotic pressure and molecular weight of proteins, and the dependence of enzyme activity on pH. Sèrensen was a member of the Leopoldina German Academy of Naturalists (1937).