Phenol co-efficient indicates: March 2011

Ans. A: Efficiency of a disinfectant The dilution of the test disinfectant which sterilizes the suspension in a given time, divided by the corresponding dilution of the phenol, is stated as the phenol coefficient (phenol=1) of the disinfectant It is used to assess the efficiency of a disinfectant Phenol coefficient It is a measure of the bactericidal activity of a chemical compound in relation to phenol. When listed numerically, the figure expressing the disinfecting power of a substance by relating it to the disinfecting power of phenol may be a function of the standardized test performed. To calculate phenol coefficient, the concentration of the test compound at which the compound kills the test organism in 10 minutes, but not in 5 minutes, is divided by the concentration of phenol that kills the organism under the same conditions. The phenol coefficient may be determined in the presence of a standard amount of added organic matter or in the absence of organic matter and the formula is given by N=1/ CT where C is the conc. of agent applied and T is the time for which agent is applied and N is the number of survivors so N is inversely propoional to dose (CT is collectively called dose)