Abstract

New selective sensors based on potentiometric transduction for iodide assessment are described. The sensors based on the use of a newly
synthesized copper (II) [N,N-bis-(1-carboxy-2-(p-hydroxybenzyl))–2,6-di(aminocarbonyl)pyridine] complex (CuL) as neutral ionophore in
plasticized poly(vinyl chloride) (PVC) membranes. The influence of lipophilic cationic and anionic additives on the response properties of
the sensors was evaluated. The fabricated sensors exhibited enhanced response towards iodide ions over the concentration range 6.3×10-6
to1.0 ×10-2 mol L-1 with a detection limit of 0.33µg mL−1
and a slope of -63.6±0.2 mV per decade. These sensors showed a fast and stable
response, good reproducibility, and long-term stability. The sensors showed a stable potential over a wide pH range (4.5–9) and exhibited
high selectivity for I−
ion in the presence of many common anions. The sensors were applied for direct potentiometric measurements of
iodide ions over the concentration range 0.8–1270 µg mL−1
and also for the titration of some metal ions (e.g. Ag+
, Hg2+) and MnO4
–
through sequential monitoring. The sequential binding of these ions with I−
ensured share stepwise titration curves with consecutive end
point breaks at the equivalent points.

Key words: iodide; copper (II) [dipeptide derivative] complex; anion recognition; PVC membrane sensors; potentiometry.