The method is not specific for phenol. It determines tho total amount of material that can be brominated under the conditions of the test. It is applicable to mixtures of about 80 % (V/V) phenol and 20 % (V/V) water. The principle is based on reaction between phenol and bromine from a measured amound of standard bromide/bromate solution. Formation of tribromophenol, follwed by iodometric determination for excess bromine using a standard volumetric solution of sodium thiosulphate.