A novel electrochemical technique, viz., cyclic voltammetry, is proposed for determination of the critical micelle concentration (cmc) of various surfactants in aqueous solution with Pt as both working electrode and counterelectrode and a saturated calomel reference electrode. The redox-active electrochemical probe and supporting electrolyte used were K4Fe(CN)e and KC1, respectively. The cmc values so obtained (SDS, 8.0 X 10~3 M; Triton X-100,3.0 X 10"4 M; Tween-80,2.2 X 10'" g/mL) were found to be in good agreement with the literature values (SDS, 8.27 X 10'3 M; Triton X-100, 2.8 x 10"4 M; Tween-80, 2.0 X 10"5 g/mL). The peak current, t"p, of each solution was measured, and the partition coefficient, K, of the electrochemical probe between water and surfactants in nonmicellar and micellar states was estimated. The results suggest that the probe is sensitive to the surfactant concentration and can reflect the changes taking place within the structure of the micellar species.

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Supplementary Material Available: Tables SI and SII, listing electronic absorption spectra and 13C NMR data, respectively, for nickel(II) compounds (2 pages). Ordering information is given on any current masthead page.

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