title: A calixarene-based ion-selective electrode for thallium(I) detection.
abstract: Three new calixarene Tl(+) ionophores have been utilized in Tl(+) ion-selective electrodes (ISEs) yielding Nernstian response in the concentration range of 10(-2)-10(-6)M TlNO3 with a non-optimized filling solution in a conventional liquid contact ISE configuration. The complex formation constants (logβIL) for two of the calixarene derivatives with thallium(I) (i.e. 6.44 and 5.85) were measured using the sandwich membrane technique, with the other ionophore immeasurable due to eventual precipitation of the ionophore during these long-term experiments. Furthermore, the unbiased selectivity coefficients for these ionophores displayed excellent selectivity against Zn(2+), Ca(2+), Ba(2+), Cu(2+), Cd(2+) and Al(3+) with moderate selectivity against Pb(2+), Li(+), Na(+), H(+), K(+), NH4(+) and Cs(+), noting that silver was the only significant interferent with these calixarene-based ionophores. When optimizing the filling solution in a liquid contact ISE, it was possible to achieve a lower limit of detection of approximately 8nM according to the IUPAC definition. Last, the new ionophores were also evaluated in four solid-contact (SC) designs leading to Nernstian response, with the best response noted with a SC electrode utilizing a gold substrate, a poly(3-octylthiophene) (POT) ion-to-electron transducer and a poly(methyl methacrylate)-poly(decyl methacrylate) (PMMA-PDMA) co-polymer membrane. This electrode exhibited a slope of 58.4mVdecade(-1) and a lower detection limit of 30.2nM. Due to the presence of an undesirable water layer and/or leaching of redox mediator from the graphite redox buffered SC, a coated wire electrode on gold and graphite redox buffered SC yielded grossly inferior detection limits against the polypyrrole/PVC SC and POT/PMMA-PDMA SC ISEs that did not display signs of a water layer or leaching of SC ingredients into the membrane.
authors.affiliation: Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Ryan
authors.initials: R
authors.lastname: Chester
authors.affiliation: Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4556, Australia.
authors.forename: Manzar
authors.initials: M
authors.lastname: Sohail
authors.affiliation: Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Mark I
authors.initials: MI
authors.lastname: Ogden
authors.affiliation: Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Mauro
authors.initials: M
authors.lastname: Mocerino
authors.affiliation: ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Universitätstrasse 16, CH-8092, Zürich, Switzerland.
authors.forename: Ernö
authors.initials: E
authors.lastname: Pretsch
authors.affiliation: Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia; Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland 4556, Australia. Electronic address: rdemarc1@usc.edu.au.
authors.forename: Roland
authors.initials: R
authors.lastname: De Marco
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D047250:Calixarenes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D017736:Ion-Selective Electrodes; D007476:Ionophores / Q000737:chemistry; D057230:Limit of Detection; D008567:Membranes, Artificial; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013793:Thallium / Q000032:analysis* / Q000737:chemistry
chemical_list: D000178:Acrylamides; D007476:Ionophores; D008567:Membranes, Artificial; C429790:poly(N,N-dimethylacrylamide); D047250:Calixarenes; D019904:Polymethyl Methacrylate; D013793:Thallium
keywords: Calixarenes; Detection limit; Ion selective electrode; Solid contact; Thallium(I)