Use of self-plasticizing EVA membrane for potentiometric anion detection

In this work, five different types of membranes were developed responsible to anion-selective electrodes. The membranes were based on tri-caprylyl-trimethyl-ammonium chloride (Aliquat-336S) supported on poly(ethylene-co-vinyl-acetate) copolymer (EVA). The sensors were prepared by solubilizing the copolymer with the appropriate exchanger in chloroform, without using of any plasticizers. The ion-selective electrodes prepared using these membranes show the utility for anions determinations in the concentration range between 10−5 and 10−1 mol l−1 in the steady-state. The membrane performance was also evaluated in FIA system using tubular electrode for salicylate and iodide. In FIA system, the electrode exhibited nernstian response for salicylate in the concentration range of 2.5×10−3 and 1.0×10−1, while for iodide from 5.0×10−4 up to 1.0×10−1 mol l−1. The systems were employed for the salicylate and iodide determination in pharmaceutical samples obtaining a relative deviation of 1.6%, when compared to the reference method.