Preservation of factor VIII activity in plasma by different freezing techniques, as determined with a chromogenic...

The preservation of factor VIII activity in frozen plasma was studied using three different freezing techniques. Two were conventional methods, i.e. ethanol bath at -40 degrees C, and deep-frozen at -80 degrees C, and the third was a novel air-based -40 degrees C freezer with metal compartments and snugly fitting flat 750 ml plasma containers. No statistically significant difference in preservation of factor VIII was observed, irrespective of freezing technique, as determined with a chromogenic substrate assay.