Fluorimetric flow-injection method for anionic surfactants based on protein–surfactant interactions†

Abstract

Surfactant–protein interactions have been widely used to study the composition of biopolymers, but their application in the quantitative analysis of surfactants has not been exploited. Here the analytical figures of merit of a sensitive spectrofluorimetric flow-injection system for the determination of an anionic surfactant, sodium dodecyl sulfate (SDS), are reported. The proposed method is based on the interactions of SDS with bovine serum albumin, a surface active protein, in the presence of a fluorescent probe, 8-anilino-1-naphthalenesulfonic acid. The linear dynamic range extends from the limit of quantification up to 1 × 10^–4M SDS under selected conditions. The relative standard deviation is 4% with a detection limit of 2 × 10^–6M SDS. The method was applied to the determination of SDS in river and tap water samples. A mechanism for the sensing chemistry involved is proposed.