Cohn's method was gentle enough that isolated albumin protein retained its biological activity.
Reprecipitation, or repetition of the precipitation step in order to improve purity, is done so by raising ethanol concentration back to 40% from the extraction stage.
Several variations of Cohn fraction were created to account for lower cost and higher yield.
[4] Cohn was able to start the Plasma Fractionation Laboratory after he was given massive funding from the government agencies and the private pharmaceutical companies.
[7] Gamma globulins are found in Fractions II and III and proved to be essential in treating measles for soldiers.
Most importantly, the gamma globulins were useful in modifying and preventing infectious hepatitis during the Second World War.
[5] Liquid fibrin sealant was used in treating burn victims, including some from the attack at Pearl Harbor, to attach skin grafts with an increased success rate.
[6] Fibrin foam and thrombin were used to control blood vessel oozing especially in liver injuries and near tumors.
[5] The first fibrinogen/fibrin based product capable of stopping arterial hemorrhage was the "Fibrin Sealant Bandage" or "Hemostatic Dressing (HD)" invented by Martin MacPhee at the American Red Cross in the early 1990s, and tested in collaboration with the U.S.
While this method proved less expensive, it was not adopted by industry because of this combination of fractions II, III, and IV, for fear of mixing and high impurities.
This method gave higher yields through recovery of some of the plasma proteins discarded in the Fractions of IV.
[10] The Mulford method, akin to the Hink, used the fractions II and III supernatant as the last step before finishing and heat treatment.
The method combined fractions IV and V, but in this case, the albumin would not be as pure, although the yields may be higher.
[10] Another variation was developed by Kistler and Nitschmann, to provide a purer form of albumin, even though offset by lower yields.
Finally, the expensive heat treatment vessels offset the lower cost compared to the cold ethanol format that do not need it.
Through a two-stage process, impurities are precipitated directly from fractions II and III supernatant at 42% ethanol, pH 5.8, temperature −5 degrees C, 1.2% protein, and 0.09 ionic strength.
Fractions I, II, III, and IV are coprecipitated at 40% ethanol, with pH of 5.4 to 7.0, and temperature −3 to −7 degrees C. Fraction V is then precipitated at pH 4.8 and −10 degrees C. The high yields are due to a combination of a simplified process, with lower losses due to coprecipitation, and use of filtration.
In general, the Cohn Process and its variations have given a huge boost to and serve as a foundation for the fractionation industry to this day.
[13] Nevertheless, this process still serves as a major foundation for the blood industry in general and its influence can be seen as it is referred to in the development of newer methods.
Although it has its drawbacks depending on the variation, the Cohn Process’ main advantage is its practical uses and its utility within pharmacological and medical industries.