Factors Influencing Electroanalytical Measurements In Aqueous Surfactant Media

Abstract

Surfactant solutions of sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and Triton X-100, have been studied for their utility as media for electroanalytical measurements. Each medium possesses a wide potential window with low background currents within which electrochemical measurements can be conducted. the potential windows at a glassy carbon electrode are +1.2 to -1.6 V for 0.1 M TEAP/SDS, 0.1 M NaCl/0.1 M SDS and 0.1 M NaCl/1.2% Triton X-100, and +0.6 to -1.6 V for 0.1 M NaCl/32 mM CTAB (V vs. Ag/AgCl (3M NaCl)). the M(II/I) redox couples of [ReCdmpe)₃]^2+/+ and [Tc(dmpe)₃]^2+/+ were used as electrochemical probes of each surfactant medium. Results are discussed In terms of the solubilization and interaction of the complexes with the micellar environment. Several factors are described which affect the general shape of the voltammograms as well as the observed values of E^o'; these include (i) the structure of the micelle as influenced by the supporting electrolyte, (ii) the electrostatic affinity of the probe complex for the micellar environment and (iii) the solubilization of each component of the redox couple in the micelle.