Anionic Surfactants as MBAS

By SM 5540C


The MBAS method has been applied successfully to drinking water samples. In wastewater, industrial wastes, and sludge, numerous materials normally present can interfere seriously if direct determination of MBAS is attempted. Most nonsurfactant aqueous-phase interferences can be removed by sublation.

Methylene blue active substances (MBAS) bring about the transfer of methylene blue, a cationic dye, from an aqueous solution into an immiscible organic liquid upon equilibration. This occurs through ion pair formation by the MBAS anion and the methylene blue cation. The intensity of the resulting blue color in the organic phase is a measure of MBAS. The method comprises three successive extractions from acid aqueous medium containing excess methylene blue into chloroform (CHCl3), followed by an aqueous backwash and measurement of the blue color in the CHCl3 by spectrophotometry at 652 nm.

-Standard Methods Online – Standard Methods for the Examination of Water and Wastewater

Method Data

SM 5540 C
Hold Time
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Method Refernce

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