A Simple Method for the Preservation of Sera by Desiccation in the Frozen State Without the use of Refrigerants

Abstract

SummaryA simple process is described for the desiccation of antisera after freezing by rapid evaporation. Freezing has been brought about by the rapid evaporation which takes place in a high vacuum in the presence of P2O5. The violent frothing which takes place when serum is exposed to a high vacuum has been controlled by a preliminary evacuation of the serum in the absence of the drying agent.No special apparatus except an efficient high vacuum pump is necessary for this process.This process has been applied for the preservation of (a) anti-horse serum, anti-ox serum, anti-human serum, anti-human globulin and anti-crystalline human albumin sera; (b) anti-sheep cell haemolysin; (c) guinea-pig complement; (d) various Salmonella antisera.Preliminary experiments are described of the application of this method to the drying of bacteria.We desire to thank Dr P. Hartley for his valuable advice and for showing us his paper prior to publication.

The osmotic pressure, after re-solution, of serum dried from the frozen state (F.D. serum)

“…Therefore we have thought that it would be of interest to publish results we obtained some years ago when testing the method for drying serum which has been described by Greaves & Adair (1936).…”

High-vacuum condensation drying of proteins from the frozen state

“…The dry mass dissolves rapidly and completely in water, yielding a fluid which apparently does not differ in physical properties from the original solution (Adair & Robinson, 1931;Greaves & Adair, 1936;Elser, Thomas & Steffen, 1935;Flosdorf & Mudd, 1935, 1938. Proteins dried in this way may be preserved for long periods of time without undergoing deterioration.…”

“…He found that by reducing the pressure slowly with a water pump, frothing could be controlled, till eventually a quiescent fluid resulted. Greaves & Adair (1936) made use of this observation for drying, from the frozen state, material in its final containers. They found that if vessels containing the protein solution were placed in a desiccator without any drying agent, and the pressure was reduced to about 12 mm.…”

“…The considerable heat of dilution of phosphorus pentoxide is probably an important factor in the efficiency of the processes of Adair & Robinson (1931) and Greaves & Adair (1936). Their techniques are applicable to small volumes of solution only, because a large amount of phosphorus pentoxide is necessary to dry a small volume of protein from the frozen state, so that only about 21 c.c.…”