The history of plasma derivatives is inextricably linked to the Cohn Process, developed by Dr. Edwin Cohn in the 1940s. During World War II, there was a desperate need for a stable, portable blood volume expander for soldiers.

The Cold Ethanol Precipitation Method

Cohn’s innovation was the use of cold ethanol fractionation. By carefully manipulating three variables—ethanol concentration, pH, and temperature—technicians could "precipitate" or drop specific proteins out of the plasma solution one by one. This allowed for the isolation of pure albumin, which could be stored at room temperature, unlike whole blood. Today, while modern techniques like chromatography have been added, the Cohn process remains the foundational "industrial blueprint" for the plasma industry.