Potentiometric Titration of Micromolar Levels of Anionic Surfactants in Model Effluents Using a Sensitive Potentiometric Sensor

Anionic surfactants have been potentiometrically determined at the ppm level using a sensitive surfactant sensor based on 1,3-didecyl-2-methylimidazolium-tetraphenylborate as a sensing ion-exchanger. Standard solutions of 3-didecyl-2-methylimidazolium chloride and cetylpyridinium chloride at concentrations of 5 x 10(-5) M were used as cationic titrants. The sensor exhibited Nernstian slope toward dodecylsulfate and dodecylbenzene sulfonate with slope values of 59.4 +/- 0.2 and 58.9 +/- 0.4 mV/concentration decade, respectively, and detection limits of 2 x 10(-7) M. The obtained recoveries of anionic surfactants in model effluents varied between 96.4 and 97.0 % with a detection limit of 0.02 mg/L.