Interdisciplinary Graduate Programme, Nanyang Technological University, 61 Nanyang Drive, Academic Block North, Singapore 637335, Singapore.
Nanyang Environment and Water Research Institute, Residues and Resource Reclamation Center, 1 Cleantech Loop, Cleantech, Singapore, 637141, Singapore.
Analyst. 2022 Oct 10;147(20):4500-4509. doi: 10.1039/d2an01108e.
Paper-based microfluidic solution sampling is a viable option for potentiometric sensors to be used for the determination of analytes in samples with high solid-to-liquid ratios. Unfortunately, heavy metal sensitive electrodes cannot be easily integrated with paper-based solution sampling as heavy metals have strong physicochemical adsorption affinity towards paper substrates. In this work, paper substrates were modified with an ion-selective membrane (ISM) cocktail (used for the preparation of Pb-ion-selective electrodes (ISEs)) and coupled with model heavy metal Pb-ISEs. It was found that the super-Nernstian response of Pb-ISEs was eliminated when 10 to 50 mg ml of the ISM cocktail was used for the modification of paper substrates. The modification of the paper substrates by Pb-ISM allowed the elimination of adsorption sites. In addition, it resulted in an improvement of sensor performance in terms of their detection limits to be similar to those for conditioned electrodes in standard beaker-based measurements. It is believed that the elimination of super-Nernstian response of the electrodes and improving the potentiometric responses and detection limits of ISEs were attributed to the compatibility improvement of the paper substrates and Pb-ISEs to the same type of ISM.
基于纸张的微流体溶液采样是一种可行的选择，可用于测定固液比高的样品中的分析物。然而，重金属敏感电极不能轻易与基于纸张的溶液采样集成，因为重金属对纸张基质具有很强的物理化学吸附亲和力。在这项工作中，纸张基质用离子选择性膜（ISM）混合物（用于制备 Pb 离子选择性电极（ISEs））进行修饰，并与模型重金属 Pb-ISEs 耦合。结果发现，当使用 10 至 50 mg ml 的 ISM 混合物修饰纸张基质时，Pb-ISE 的超 Nernst 响应被消除。通过 Pb-ISM 对纸张基质进行修饰，可以消除吸附位点。此外，它还改善了传感器的性能，使其检测限与标准烧杯测量中条件化电极的检测限相似。据信，电极的超 Nernst 响应的消除以及 ISEs 的电位响应和检测限的提高归因于纸张基质和 Pb-ISEs 与同类型 ISM 的兼容性的提高。
