The Principles involved in the Standardisation of Disinfectants and the Influence of Organic Matter upon Germicidal value

Abstract

In any method of standardisation it is necessary that the test shall be carried out at a constant temperature, as the disinfection process has a high temperature coefficient. For any method to be of general application, it is also necessary that the temperature selected shall be adhered to in all determinations, since the temperature coefficient of disinfection varies for different disinfectants. The temperature adopted was 20° C. In the case of vegetative organisms a disinfectant varies in efficiency as much as ten times according to the organism against which it is tested. Some disinfectants are more efficient against one vegetative species of bacteria, others against another. The presence of 10% blood serum reduces the efficiency of 1% phenol about 12%. The effect upon emulsified disinfectants is somewhat greater. With mercuric chloride the reduction was much greater, a 0·5% solution being reduced to from 0·6 to 0·06 of its original value as the concentration of serum was increased from 5 to 30%.