Selective Determination of Traces of Gold(III) Based on Fluorescence Quenching of Perylene in Micelles

Abstract

We found a selective fluorescence quenching of perylene by gold(III) in a micellar system of polyoxyethylene-type nonionic surfactants. Nitric acid was essential for incorporating gold(III) into the micelles, but deactivated the excitation of perylene. The deactivation was minimized by solubilizing perylene in micelles of nonionic surfactants having no aromatic moiety. Among the nonionic surfactants tested, Brij-35, having the shortest hydrocarbon chain and the highest polymerization degree of oxyethylene, was the best choice for obtaining the greatest quenching effect of gold(III). A linear relationship was obtained in the range of 5 × 10⁻⁸∼5 × 10⁻⁷ M of gold(III) in the presence of 1 M nitric acid and 0.05% (w/v) Brij-35. The Stern-Volmer quenching constant, K_sv, for gold(III) was 1.28 × 10⁷ M⁻¹. On the other hand, the K_sv (M⁻¹) values were 4.3 × 10⁴ for platinum(II), 8 × 10³ for palladium(II), and 5 × 10² for iron(III), being far smaller than the value for gold(III). Other metal ions including aluminum(III), manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), silver(I), tin(IV), and lead(II) at 10⁻⁴ M had negligible quenching effect. The present method can be applicable to the selective determination of traces of gold(III).