Novel fluorimetric bulk optode membrane based on 5,8-bis((5′-chloro-8′-hydroxy-7′-quinolinyl)methyl)-2,11-dithia-5,8-diaza-2,6-pyridinophane for selective detection of lead(II) ions |
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Authors: | Mojtaba Shamsipur Marzieh Sadeghi Andrea Bencini Alessandra Garau |
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Affiliation: | a Department of Chemistry, Razi University, Kermanshah, Iran b Department of Chemistry, Lorestan University, Khorramabad, Iran c Dipartimento di Chimica, Università degli Studi di Firenze, Polo Scientifico, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy d Dipartimento di Chimica Inorganica ed Analitica, Università degli Studi di Cagliari, S.S. 554 Bivio per Sestu, 09042 Monserrato (CA), Italy |
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Abstract: | A novel fluorescence chemical sensor for the highly sensitive and selective determination of Pb2+ ions in aqueous solutions is described. The preliminary potentiometric and spectrofluorimetric complexation studies in solution revealed that the lipophilic ligand 5,8-bis((5′-chloro-8′-hydroxy-7′-quinolinyl)methyl)-2,11-dithia-5,8-diaza-2,6-pyridinophane (L2) forms a highly stable and selective PbL2]2+ and Pb(L2)2]2+ complexes which results in a strong fluorescence quenching of the ligand. Thus, a novel fluorescence Pb2+ sensing system was prepared by incorporating L2 as a neutral lead-selective fluoroionophore in the plasticized PVC membrane containing tetrakis(p-chlorophenyl) borate as a liphophilic anionic additive. The response of the sensor is based on the strong selective fluorescence quenching of L2 by Pb2+ ions. At pH 5.5, the proposed sensor displays a calibration curve over a wide concentration range of 3.0 × 10−7 to 2.5 × 10−2 M with a relatively fast response time of less than 5 min. In addition to high stability, reversibility and reproducibility, the sensor shows a unique selectivity towards Pb2+ ion with respect to common coexisting cations. The proposed fluorescence optode was successfully applied to the determination of lead in plastic toys and tap water samples. |
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Keywords: | Optode membrane Fluoroionophore Selective Pb2+ determination Fluorescence quenching |
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