Chester Ryan, Sohail Manzar, Ogden Mark I, Mocerino Mauro, Pretsch Ernö, De Marco Roland
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.
Anal Chim Acta. 2014 Dec 3;851:78-86. doi: 10.1016/j.aca.2014.08.046. Epub 2014 Aug 27.
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.
三种新型杯芳烃铊离子载体已用于铊离子选择性电极（ISEs）中，在传统液接ISE配置下，使用未优化的填充溶液时，在10⁻² - 10⁻⁶M硝酸铊浓度范围内产生能斯特响应。采用夹心膜技术测量了两种杯芳烃衍生物与铊（I）的络合形成常数（logβIL）（即6.44和5.85），由于在这些长期实验中离子载体最终沉淀，另一种离子载体无法测量。此外，这些离子载体的无偏选择性系数对Zn²⁺、Ca²⁺、Ba²⁺、Cu²⁺、Cd²⁺和Al³⁺表现出优异的选择性，对Pb²⁺、Li⁺、Na⁺、H⁺、K⁺、NH₄⁺和Cs⁺具有中等选择性，需要注意的是，银是这些基于杯芳烃的离子载体的唯一重要干扰物。在优化液接ISE的填充溶液时，根据国际纯粹与应用化学联合会（IUPAC）的定义，有可能实现约8nM的检测下限。最后，还在四种固体接触（SC）设计中对新型离子载体进行了评估，结果显示能产生能斯特响应，其中使用金基底、聚（3 - 辛基噻吩）（POT）离子 - 电子换能器和聚（甲基丙烯酸甲酯） - 聚（癸基丙烯酸甲酯）（PMMA - PDMA）共聚物膜的SC电极响应最佳。该电极的斜率为58.4mV/decade⁻¹，检测下限为30.2nM。由于存在不希望的水层和/或氧化还原介质从石墨氧化还原缓冲SC中浸出，金和石墨氧化还原缓冲SC上的涂层丝电极的检测限远低于聚吡咯/PVC SC和POT/PMMA - PDMA SC ISEs，后者未显示出水层迹象或SC成分浸出到膜中的情况。
