“…Free solution electrophoresis and electrophoresis stabilized by density gradients give similar results (512) and density gradient systems can be used for measuring mobilities (2) Paper is still by far the most commonly used supporting medium, but there is growing evidence that cellulose acetate films give better resolution and are easier to use (9,315,442,504,546,575, 590, 613, 648). Detailed instructions for electrophoresis on cellulose acetate have been published (285).…”