Department of Chemistry , Colorado State University , Fort Collins , Colorado 80521 , United States.
Department of Inorganic and Analytical Chemistry , The University of Geneva , Quai Ernest Ansermet 30 , 1211 Geneva 4 , Switzerland.
Anal Chem. 2018 Apr 3;90(7):4894-4900. doi: 10.1021/acs.analchem.8b00559. Epub 2018 Mar 21.
In this study, paper-based microfluidic devices (μPADs) capable of K quantification in aqueous samples, as well as in human serum, using both colorimetric and distance-based methods are described. A lipophilic phase containing potassium ionophore I (valinomycin) was utilized to achieve highly selective quantification of K in the presence of Na, Li, and Mg ions. Successful addition of a suspended lipophilic phase to a wax printed paper-based device is described and offers a solution to current approaches that rely on organic solvents, which damage wax barriers. The approach provides an avenue for future alkali/alkaline quantification utilizing μPADs. Colorimetric spot tests allowed for K quantification from 0.1-5.0 mM using only 3.00 μL of sample solution. Selective distance-based quantification required small sample volumes (6.00 μL) and gave responses sensitive enough to distinguish between 1.0 and 2.5 mM of sample K. μPADs using distance-based methods were also capable of differentiating between 4.3 and 6.9 mM K in human serum samples. Distance-based methods required no digital analysis, electronic hardware, or pumps; any steps required for quantification could be carried out using the naked eye.
本研究描述了一种基于纸张的微流控装置（μPAD），该装置能够使用比色法和基于距离的方法在水溶液样品以及人血清中定量钾。利用含有亲脂性钾离子载体 I（缬氨霉素）的亲脂相，在存在 Na、Li 和 Mg 离子的情况下实现了对 K 的高度选择性定量。成功地将悬浮的亲脂相添加到蜡印纸上的微流控装置中，并为目前依赖于有机溶剂的方法提供了一种解决方案，因为有机溶剂会破坏蜡质屏障。该方法为未来利用 μPAD 进行碱/堿定量提供了一种途径。比色斑点测试允许仅使用 3.00 μL 的样品溶液，从 0.1-5.0 mM 定量 K。基于距离的选择性定量需要小体积的样品（6.00 μL），并且响应足够灵敏，可以区分 1.0 和 2.5 mM 的样品 K。使用基于距离的方法的 μPAD 还能够区分人血清样品中的 4.3 和 6.9 mM K。基于距离的方法不需要数字分析、电子硬件或泵；定量所需的任何步骤都可以用肉眼进行。
