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.
