1997 Volume 45 Issue 12 Pages 2104-2106
The surface potential (Δψ) of the mixed micelles composed of dibucaine hydrochloride (DC) and nonionic heptaethylene glycol dodecyl ether (HED) has been estimated by measuring the fluorescence intensity of ammonium 8-anilino-1-naphthalenesulfonate (ANS) as a fluorescent probe. The value of +Δψ increases with an increasing mole fraction of DC (XDC) and decreases with increasing ionic strength (I). These changes are due to the effects of the ositive charge of DC and of the ionic atmosphere of Cl-, respectively. Surface charge density (σ) was, therefore, determined from Δψ according to the Gouy-Chapman theory, with a results that σ is nearly independent of I and proportional to XDC. These results have led to a conclusion that the state of the diffuse layer surrounding the Stern layer at the micelle surface is represented well by the Gouy-Chapman theory.
