Detergents (anionic surfactants, MBAS) Test Kits

Visual Kits

Range MDL Method Kit Catalog No. Refill Catalog No.
0-3 ppm 0.125 ppm Methylene Blue K-9400 R-9400

Instrumental Kits

Range Method Kit Catalog No.
0-2.50 ppm Methylene Blue I-2017



Detergents can be introduced into the water supply by industry, soap manufacturers, and private households. Environmental analysts often include a determination of anionic detergents when assessing surface water pollution.


The Methylene Blue Method


References: USEPA Methods for Chemical Analysis of Water and Wastes, Method 425.1 (1983). APHA Standard Methods, 21sted., Method 5540 C (2005). ASTM D 2330-02 , Methylene Blue Active Substances.


The methylene blue active substances (MBAS) method is used in a 3-minute procedure to measure anionic detergents in the 0-3 ppm (mg/L) range. The procedure features a unique extraction/sampling technique that eliminates several steps required in other test procedures and provides increased sensitivity.


Anionic detergents react with methylene blue to form a blue-colored complex that is extracted into an immiscible organic solvent. Results are expressed in ppm (mg/L) as linear alkylbenzene sulfonate (LAS), equivalent weight 325.


Shelf-life: The shelf-life of R-9400 is 5 months and of R-9404 and R-9423 is 8 months. We recommend stocking quantities accordingly.