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

Abstract

A 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.