Arne Tiselius (är´nə tēsā´lyəs), 1902–71, Swedish biochemist. He received the 1948 Nobel Prize in Chemistry for developing new methods of separating and detecting colloids. One system (electro-phoresis) employs an electrical apparatus (Tiselius apparatus) for the separation of heavy molecules in solution; the other is a method of adsorption analysis that permits the differentiation and separation of substances, e.g., proteins, sugars, salts, and acids. Tiselius isolated the virus of mouse paralysis and developed synthetic blood plasma. In 1925 he joined the faculty of the Univ. of Uppsala; he did research at the Institute for Advanced Studies at Princeton in 1934–35 and at the Rockefeller Institute, New York City, in 1939.