Colorimetric determination of anionic surfactants by MBAS method in surface waters and wastewater

Abstract

This method is suitable for the determination of anionic surfactants in surface waters and wastewater. Anionic surfactants can be detected using a simple and precise method based on their activity with methylene blue active substance (MBAS). This method, derived and modified from IDEAM (2007), involves three consecutive extractions from an acidic aqueous solution, where an excess of methylene blue is added, into a chloroform organic phase. Subsequently, the blue color in the organic phase is measured by spectrophotometry at 652 nm (Standard Methods, 2005). However, it is important to consider the potential presence of other active substances that may react with methylene blue in the sample. Under controlled laboratory conditions, this methodology enables the precise quantification of MBAS concentrations commencing at 0.50mg/L.