FLUOROMETRIC FLOW-INJECTION METHOD FOR ANIONIC SURFACTANTS BASED ON PROTEIN-SURFACTANT INTERACTIONS

Surfactant-protein interactions have been widely used to study the com position of biopolymers, but their application in the quantitative ana lysis of surfactants has not been exploited. Here the analytical figur es of merit of a sensitive spectrofluorimetric flow-injection system f or 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 pre sence of a fluorescent probe, 8-anilino-1-naphthalenesulfonic acid. Th e linear dynamic range extends from the limit of quantification up to 1 x 10(-4) M SDS under selected conditions. The relative standard devi ation is 4% with a detection limit of 2 x 10(-6) M 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.