Blood plasma, the liquid component of whole blood, is made up primarily of water and contains small quantities of minerals, salts, ions, nutrients and proteins.

There is a large variety of proteins in plasma and many of these, such as albumin, immunoglobulins and clotting factors have important therapeutic properties.

Plasma fractionation process developed by Edwin J. Cohn exploits differences in solubility of proteins at different pH, temperature and ethanol concentration to precipitate out desired proteins under different set of conditions. However, modern plasma fractionation processes are increasingly employing other purification techniques such as diafiltration, ultrafiltration and chromatography to achieve higher purity and product activity.