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E-Journal of Chemistry
Volume 8 (2011), S1, Pages S237-S244

Application of N-Quinoline-2-carboxamido-8-aminoquinoline in Fabrication of a Ho(III)-PVC Membrane Sensor

Hassan Ali Zamani,1 Samaneh Langroodi,1 and Soraia Meghdadi2

1Department of Applied Chemistry, Quchan Branch, Islamic Azad University, Quchan, Iran
2Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran

Received 22 April 2011; Accepted 3 July 2011

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The N-quinoline-2-carboxamido-8-aminoquinoline (QCA) was used as a suitable ion carrier in the construction of a Ho(III) PVC-based membrane sensor. This sensor demonstrated good selectivity and sensitivity towards the holmium ion for a broad variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The proposed electrode exhibits a linear dynamic range between 1.0×10-6 and 1.0×10-2 M, with a near Nernstian slope of 20.4±0.3 mV per decade and a detection limit of 4.2×10-7 M. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 56% nitrobenzene, 2% sodium tetraphenyl borate, 10% oleic acid and 2% QCA. The potentiometric response of the constructed electrode is pH independent in the range of 2.4-7.4. The sensor possesses the advantages of short conditioning time, fast response time (∼ 5 s) and especially, good selectivity towards transition and heavy metal and some mono, di and trivalent cations. The Ho3+ sensor was successfully applied as an indicator electrode in the potentiometric titration of Ho(III) ions with EDTA. The electrode was also used for the determination of Ho3+ ions in mixtures of different ions and the determination of the fluoride ion in mouth wash solutions.