Surfactant-Selective Electrode Based on Plasticized Poly(vinyl chloride) Membrane and Its Application

The surfactant-selective electrode based on the poly(vinyl chloride) membrane plasticized with o-nitrophenyl octyl ether shows the Nernstian response to anionic surfactants as well as to cationic ones, e.g., the dodecylsulfate ion and the dodecyltrimethyl ammonium ion. The response time of the electrode is in the order of a few seconds. The electrode is highly selective to the dodecylsulfate ion over inorganic anions. The dodecylsulfate ion selective electrode was applied to the successive potentiometric detection of surfactants by high performance liquid chro-matography. Four alkylsulfates were successfully detected with the electrode, after being separately eluted with water-methanol mixture through the reversed phase packing column. The electrode was shown to be useful for the determination of critical micelle concentrations of surfactants in the presence of electrolytes.