Sensors and Actuators B 120 (2007) 545–550 Construction of a highly selective PVC-based membrane sensor for Ce(III) ions Hassan Ali Zamani a,∗ , Mohammad Reza Ganjali b , Mahdi Adib b a Department of Chemistry, Quchan Branch, Islamic Azad University, Quchan, Iran b Department of Chemistry, Tehran University, Tehran, Iran Received 6 January 2006; received in revised form 7 March 2006; accepted 8 March 2006 Available online 18 April 2006 Abstract A highly Ce(III) ion-selective poly vinyl chloride (PVC) membrane sensor based on N ′ -[(2-hydroxyphenyl)methylidene]-2-furohydrazide (NHMF) as an excellent sensing material is successfully developed. The electrode shows a good selectivity for Ce(III) ions with respect to most common cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor exhibits a wide linear response with a slope of 19.4 ± 0.3 mV/decade over the concentration range of 1.0 × 10 -5 to 1.0 × 10 -1 M, and a detection limit of 7.6 × 10 -6 M of Ce(III) ions. The sensor response is independent of pH in the range of 3.5–10.0. The proposed electrode was applied as an indicator electrode in potentiometric titration of Ce(III) ions with EDTA and C 2 O 4 2 . It was also successfully applied in the determination of cerium ions in aqueous samples. © 2006 Elsevier B.V. All rights reserved. Keywords: Potentiometry; Ce(III) ion-selective electrode; PVC membrane; N ′ -[(2-Hydroxyphenyl)methylidene]-2-furohydrazide 1. Introduction During the last decades, many intensive studies have been reported on the design and synthesis of highly selective carriers as sensory molecules for ion-selective electrodes (ISEs) [1–3]. The increasing use of ion sensors in the fields of environmen- tal, agricultural and medicinal analysis is stimulating analytical chemists to develop new sensors for the fast, accurate, repro- ducible and selective determination of various species. In the past few decades, considerable efforts have led to the develop- ment of selective sensors for alkali, alkaline earth, and heavy metals [4]. It is noteworthy that, despite the urgent need for a Ce(III)- selective electrode for potentiometric monitoring of cerium in many industrial, geological, and chemical samples [5–8], there are only a limited number of reports on the development of highly selective ionophores for cerium in literature [9–12]. Recently, we reported a number of highly selective and sensitive membrane sensors for alkaline earth and transition metal ions [13–17]. In this work, we report the use of N ′ - ∗ Corresponding author. Tel.: +98 581 2224180; fax: +98 581 2226093. E-mail address: haszamani@yahoo.com (H.A. Zamani). [(2-hydroxyphenyl)methylidene]-2-furohydrazide (NHMF) as an excellent ionophore for preparation of a highly Ce(III) ion- selective electrode (Fig. 1). 2. Experimental 2.1. Reagents Reagent grade dibutyl phthalate (DBP), benzyl acetate (BA), nitrobenzene (NB), sodium tetraphenyl borate (NaTPB), tetrahydrofuran (THF) and high relative molecular weight poly vinyl chloride (PVC) were purchased from Merck and Aldrich, and used as received. The nitrate and chloride salts of all cations used (all from Merck and Aldrich) were of the highest purity available and used without any further purification except for vacuum drying over P 2 O 5 . Triply distilled de-ionized water was used throughout. 2.2. Synthesis of NHMF A mixture of 2-furohydrazide (0.01 mol, 1.26 g), 2- hydroxybenzaldehyde (0.01 mol, 1.22 g) and a catalytic amount of acetic acid was refluxed in ethanol (70 mL) for 2 h. Then the solvent was evaporated to 20 mL. After cooling to room 0925-4005/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.snb.2006.03.013