This standard specifies a manual or mechanical method for the determination of the anionic active matter contained in detergents. This method is applicable to solids and aqueous solutions of the active material. The relative molecular weight of the anionic active matter must be known. The method is not applicable in the presence of cationic surfactants. The manual method is applicable for the determination of alkylbenzene sulfonates, alkanesulfosuccinates, sulfates and hydroxysulfates, alkylphenol sulfates, methoxy and ethoxysulfates of fatty alcohols, dialkylsulfosuccinates and other active materials containing one hydrophilic group per molecule. The mechanical method is applicable to all the aforementioned products only if it gives results comparable to those obtained by applying the manual method. NOTE- Hydrotropic sulfonates, of low relative molecular weight (toluenesulfonate, xylenesulfonates), do not interfere when they are present at concentrations lower than 15% by weight based on active matter. At higher concentrations, their influence must be studied for each particular case. Soaps, urea, and (ethylenedinitrile)tetraacetic acid salts do not interfere. In the presence of nonionic surfactants, their influence must be studied in each particular case. The typical inorganic components of detergent formulations, such as sodium chloride, sulfates, borates, tripolyphosphates, perborates, silicates, etc., do not interfere; but bleaching agents other than perborate must be destroyed before analysis, and the sample must be completely soluble in water.