The aim of this study was the determination of the critical micelle concentration (CMC) of the sodium dodecyl sulfate (SDS) surfactant using spectroscopic and conductimetric determinations and to compare these methodologies in the determination of the CMC of different humic acids (HA). The CMC obtained by conductimetric determination was satisfactory. By spectroscopic determination two values of the CMC were obtained for HA. These values can be to due the intra and intermolecular interactions in the HA structure.
spectroscopy and conductimetric determination; critical micelle concentration; humic acids
