Determination of critical micelle concentration of cetyltrimethylammonium bromide: Different procedures for analysis of experimental data

Abstract

Conductivity of two micellar systems was measured in order to determine critical micelle concentration (CMC) of cetyltrimethylammonium bromide (CTAB). Those systems were: CTAB in water and CTAB in binary mixture acetonitrile (ACN)-water. Conductivity (κ)- - concentration (c) data were treated by four different methods: conventional method, differential methods (first and second derivative) and method of integration (methods A-D, respectively). As CTAB in water micellar system shows a sharp transition between premicellar and postmicellar part of the κ/c curve, any of the applied methods gives reliable CMC values and there is no statistically significant difference between them. However, for CTAB in ACN-water mixture micellar system the integration method for CMC determination is recommended due to a weak curvature of κ/c plot.