This standard specifies a method for determining, in detergents, the anionic active substances that are hydrolyzable and non-hydrolyzable in an acid medium. These active materials include alkyl sulfates and alkylhydrosulfates, as well as ethoxysulfates of alkylphenols and fatty alcohols. The average relative molecular weight of both types of active materials must be known or determined previously, if their contents are to be expressed as a percentage by weight. If the detergent contains perborate, it must be destroyed before hydrolysis.