Inactivation of mycoplasma in serum with binary ethyleneimine

A method of inactivating mycoplasma contaminants in sera by using binary ethyleneimine was tried. When used at the concentration recommended for inactivating viruses, 0.001 M, binary ethyleneimine inactivated only two of five mycoplasma species. Even at a concentration of 0.01 M, the compound did not consistently inactivate all mycoplasmas.