Kinetics of Virus Inactivation by Ammonia

Ammonia has been shown to be virucidal in sludge and NH4 Cl solutions, although the rates at which viruses are inactivated have not been thoroughly studied. In the present studies, the kinetics of the poliovirus type 1 (strain CHAT) and bacteriophage f2 inactivation were examined in such a way that the effects of OH− and NH4 + could be separated from those of NH3 . Purified virus stocks were placed into solutions of NH4 Cl and control solutions containing an equivalent concentration of NaCl and incubated at 20°C. The percentage of virus surviving was calculated, and the kinetics were evaluated by constructing semilogarithmic plots of data. At all pH values and NH3 concentrations studied, the kinetics of the inactivation of both viruses were pseudo-first order. OH− had no measurable effect on the viruses, whereas the effects of NH4 + and Na+ were similar. A dose-response relationship between NH3 and the viruses was also found. Bacteriophage f2 was approximately 4.5 times more resistant to the effects of NH3 than was poliovirus.