Selective separation of dodecyltrimethylammonium bromide from other cationic and nonionic surfactants

Abstract

Thin-layer chromatography (TLC) of cationic and nonionic surfactants has been performed on soil, silica gel, alumina, and kieselguhr layers using aqueous solutions of ammonium sulfate and urea as mobile phases. Four stationary phases and fifteen mobile phases were used to examine the mobility of the surfactants and to discover the best TLC system for selective separation of dodecyltrimethylammonium bromide (DTAB) from multicomponent mixtures of other surfactants. The mobility of all the surfactants was insignificant on soil, alumina, and silica gel, irrespective of the nature of the mobile phase. Some of the surfactants were mobile on kieselguhr. Among the TLC systems studied, kieselguhr-0.1 m ammonium sulfate was best for achieving selective separation of DTAB from other surfactants. A salting-out effect on DTAB is reported. The stability of the mixture of surfactants on the plate and in solution was also examined. The limit of detection of DTAB was 0.3 μg per zone.