Ampurdanés Jordi, Crespo Gastón A, Maroto Alicia, Sarmentero M Angeles, Ballester Pablo, Rius F Xavier
Department of Analytical and Organic Chemistry, University of Rovira i Virgili, Marcel.lí, Domingo, s/n. 43007, Tarragona, Spain.
Biosens Bioelectron. 2009 Oct 15;25(2):344-9. doi: 10.1016/j.bios.2009.07.006. Epub 2009 Jul 16.
A new solid-contact ion-selective electrode has been developed for determining choline and derivatives in aqueous solutions. The backbone of this new potentiometric sensor is the conjunction of the cavitand receptor, as the molecular recognition element, and a network of non-carboxylated single-walled carbon nanotubes, acting as a solid transducer material. The octaamide cavitand, a synthetic receptor that is highly selective for biologically important trimethyl alkylammonium cations such as choline, acetylcholine or carnitine, makes the selective determination of these compounds possible for the first time. The guest-host interaction takes place in the acrylate ion-selective membrane of the solid-contact electrode. The sensor was characterized by electrochemical impedance spectroscopy and environmental scanning electron microscopy. The new electrode displays a nearly Nernstian slope (57.3+/-1.0 mV/decade) and very stable behaviour (DeltaE/Deltat=224 muVh(-1)) throughout the dynamic range (10(-5) to 10(-1)M). The limit of detection of 10(-6.4)M and the high selectivities obtained will enable choline and derivatives to be determined in biological samples. Finally, the stability of the electrical potential of the new solid-contact electrode was examined by performing current-reversal chronopotentiometry and the influence of the interfacial water film was evaluated by the potentiometric water layer test.
一种新型的固体接触式离子选择性电极已被开发出来，用于测定水溶液中的胆碱及其衍生物。这种新型电位传感器的核心是将作为分子识别元件的穴状配体受体与作为固体传感材料的非羧基化单壁碳纳米管网络相结合。八酰胺穴状配体是一种对胆碱、乙酰胆碱或肉碱等具有生物学重要性的三甲基烷基铵阳离子具有高度选择性的合成受体，首次使得对这些化合物的选择性测定成为可能。客体 - 主体相互作用发生在固体接触电极的丙烯酸酯离子选择性膜中。该传感器通过电化学阻抗谱和环境扫描电子显微镜进行了表征。新型电极在整个动态范围（10^(-5) 至 10^(-1) M）内显示出近乎能斯特斜率（57.3 ± 1.0 mV/十倍浓度变化）和非常稳定的性能（ΔE/Δt = 224 μV h^(-1)）。检测限为 10^(-6.4) M，所获得的高选择性将能够测定生物样品中的胆碱及其衍生物。最后，通过进行电流反向计时电位法研究了新型固体接触电极电位的稳定性，并通过电位水层测试评估了界面水膜的影响。
