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A Lead‐Selective Membrane Electrode Based Upon a Phosphorylated Hexahomotrioxacalix[3]Arene
Author(s) -
Yaftian Mohammad Reza,
Parinejad Massoumeh,
Matt Dominique
Publication year - 2007
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200700216
Subject(s) - chemistry , ionophore , selectivity , perchlorate , sodium tetraphenylborate , tetraphenylborate , detection limit , electrode , inorganic chemistry , membrane , ion selective electrode , dichloromethane , aqueous solution , nuclear chemistry , analytical chemistry (journal) , solvent , ion , chromatography , organic chemistry , biochemistry , catalysis
Solvent extraction of a mixture of Pb II , Mn II , Fe III , Co II , Ni II and Cd II in aqueous perchlorate medium by a phosphorylated hexahomotrioxacalix[3]arene ( calix ‐3) in dichloromethane shows a significant selectivity towards lead ions. The ligand can also be incorporated into a membrane to provide a new lead ion‐selective electrode (Pb II ‐ISE). A plasticized PVC membrane containing 30% PVC, 53.5% ortho ‐nitrophenyloctylether (NPOE), 4.5% sodium tetraphenylborate (NaTPB) and 12% ionophore was directly coated on a graphite rod. This sensor gave a good Nernstian response of 29.7 ± 0.7 mV decade −1 over a concentration range of 1 × 10 −8 – 1 × 10 −4 M of lead ions, independent of pH in the range 3‐7, with a detection limit of 0.4 × 10 −8 M. The dynamic response time of the electrode to achieve a steady potential was very fast and found to be less than 7 s. The selectivity relative to Ag + , NH 4 + , Li + , Na + , K + , Ca 2+ , Sr 2+ , Ba 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Fe 3+ , La 3+ , Sm 3+ , Dy 3+ , Er 3+ , Y 3+ and Th 4+ was examined. The electrode exhibits adequate stability with good reproducibility (with a slope of 29.6 ± 1.5 mV for 8 weeks). The characteristics of the sensor are compared with those of a tetraphosphorylated calix[4]arene ( calix ‐4) based Pb II ‐ISE, reported recently. The electrode was successfully used as an indicator electrode for a potentiometric titration of a lead solution using a standard solution of EDTA. The applicability of the sensor for lead ion measurements in various synthetic samples was also investigated.