Several analytical methods have been used in determining the quantity of detergent in water. The most common analytical method in Japan uses methylene blue (MB, a cationic dye) in association with an anionic detergent in which the neutral compound with an anionic detergent in which the neutral compound produced is extracted into chloroform (1-2), according to the Japanese Industrial Standard (JIS MB method). Similar methods have also been published in this Journal in which copper-methamphetamine ion is used instead of methylene blue (3-4). The Ponal Kit Abs method (5) is another technique. It uses a purple dye, a cobalt (III) complex cation, to produce a neutral compound with anionic detergent; benzene is the extraction solvent. However, all the above methods require organic solvents and expensive lab equipment for analysis, such as an atomic solvents and expensive lab equipment for analysis, such as an atomic absorption spectrometer, an anodic stripping voltammeter, and a spectrophotometer, and are not suitable for high school experiments.