Surfactants decrease surface tension at the interface between a liquid and another solid, liquid, or gaseous phase, they are used in industry, agriculture, scientific studies and everyday life (cleaning agents, spot removers, cosmetics, etc.). The most widely used anionic surfactants include sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), sodium dodecane sulfonate (SDSA), sodium dioctyl sulfosuccinate (SDOSSA).

The HI96782-25 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents use an adaptation of Standard Methods for the Examination of Water and Wastewater, 23rd Edition, 5540C, Anionic Surfactants as MBAS. Determination of anionic surfactants by measurement of the Methylene Blue Active Substances (MBAS) index. Anionic surfactants react with methylene blue in an alkaline medium, this reaction results in salts that are extracted using chloroform. The blue color of the organic phase is determined photometrically.