When detergent is mentioned, it is meant the general name of the chemicals used in cleaning works. Detergents generally consist of organic substances with surface active properties and other substances that assist in cleaning. Surfactants or surface-stressed molecules by chemical expression are polar molecules of high molecular weight. One end of these molecules has a high solubility in water. This is due to the hydrolysis of carboxyl sulfate, sulfonate or hydroxyl groups at this end of the molecule. The other end of these molecules has a high solubility in oil. This depends on organic groups.

Since 1950, soap has been replaced by synthetic detergents. The biggest advantage of these detergents is that they give results without wasting even in hard water. 20-30 percent of the detergents on the market consists of active ingredients and 70-80 percent consists of different additives. The most commonly used additives are sodium sulfate, sodium tripolyphosphate, sodium silicate and sodium pyrophosphate. Synthetic surfactants are classified into three groups: anionic, nonionic and cationic detergents.

Most of the surfactants are anionic surfactants. For this reason, determination of anionic surfactants is generally carried out in wastewater and domestic water.

In the MBAS method, the active substance methylene blue combines with methylene blue, a type of cationic dye. In other words, MBAS anion and methylene blue cation form a pair. The blue hue after this merger indicates the amount of MBAS. Anionic surfactants are one of the most important substances with MBAS activity.

MBAS consists of the initials of the English Methylene Blue Active Subtance, which means methylene blue active substance.

Within the scope of chemical analyzes, surface active substance determination (MBAS) studies are carried out by authorized laboratories. In these studies, standards and test methods issued by national and international organizations are followed.