Potentiometric determination of anionic surfactants using a new ion-pair-based all-solid-state surfactant sensitive electrode

An all-solid-state surfactant sensitive electrode has been prepared, based on a teflonised graphite conducting substrate coated with plasticised PVC-membrane containing a new synthesized tetrahexadecylammonium-dodecylsulfate as anionic surfactant sensing material. The electrode exhibited Nernstian response (58.1 mV/decade) for dodecylbenzensulfonate and a near-Nernstian response (64.2 mV/decade) for dodecylsulfate. The electrode was used as end-point indicatior for potentiometric surfactant titrations. The selectivity coefficients relating to the common inorganic and organic anions have been calculated by modelling of Nikolskii-Eisenman equation. Several commercial surfactants have been also titrated. The electrode enables the titration of shorter hydrocarbon chain anionic surfactants, as well.