All-solid-state potentiometric sensors sensitive to nonionic surfactants based on ionophores containing ethoxylate units

Earlier work of potentiometric Ion-selective electrodes (ISEs) sensitive to nonionic surfactants of the polyethoxylate type is further extended. The I SEs constructed were all-solid-state sensors with plasticized PVC membranes . The sensing material was a tetraphenylborate salt of the barium complex w ith a polyethoxylate nonionic surfactant. As membrane component, the combin ations of two polyethoxylates of the nonylphenoxy type, which differed in t he number of oxyethylene units (5 or 12), and two different plasticizers, ( o-nitrophenyloctyl ether and o-nitrophenylphenyl ether), were tested. The r esponse of these electrodes to different nonionic surfactants and the inter ference effect of several species has been evaluated. For all the types of tested electrodes, the sensitivities shown were ca. 30.0 mV dec(-1) and the limit of detection, ca. 10(-5) M, when a nonylphenoxyde with 12 oxyethylen e units was used as standard. The membrane with the best response character istics was then applied in potentiometric titrations of this kind of surfac tants in the presence of Ba2+ ion and using tetraphenylborate as the titran t. (C) 2001 Elsevier Science B.V. All rights reserved.