Determination of dialkyldimethylammonium compounds and other cationic surfactants in sewage water and activated sludge

A method for the extraction and clean-up of four groups of cationic surfactants in sewage water and activated sludge is reported. In the case of sewage water, this is based on the extraction of the acidified aqueous sample with chloroform, centrifugation, purification by back-extraction with water and clean-up by alumina column chromatography. Activated sludge was extracted with methanolic hydrochloric acid after centrifugation. The extract was evaporated to dryness and re-dissolved in chloroform before further clean-up. The applicability of this analytical scheme to the new "esterquats" is discussed.