INDIRECT AAS DETERMINATION OF CATIONIC SURFACTANTS IN WASTE EFFLUENTS AND SHAMPOOS

An indirect atomic absorption spectrometric (AAS) method using electrothermal atomization (ETAAS) for the determination of cationic surfactants has been proposed. The method involves ion-pair formation between cationic surfactant and sodium hexanitro-cobaltate (III), extraction of the ion-pair into 1,2-dichloroethane and determination of cobalt concentration in organic phase by ETAAS and hence indirectly relating to the cationic surfactant concentrations. Surfactants of the anionic and nonionic group do not interfere to a great extent, and matrix interferences from many other cations, anions and organics are also not observed. The method has been successfully applied to cationic surfactant determination in waste water and hair rinsers. Relative standard deviation values (RSD) of 3.2% for waste water samples and 4.3% for shampoo were observed in these analyses.