Industrial facilities that use detergents to clean machinery can discharge anionic detergents into the water supply. Soap manufacturers also discharge detergents. Other sources are household cleaners and personal care products. Environmental analysts often include a determination of anionic detergents when assessing surface water pollution.

The Colorimetric Method. The methylene blue active substances (MBAS) method is used in a 3-minute procedure to measure anionic detergents. 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: 8 months. We recommend stocking quantities that will be used within 7 months.