Pergel E, Gyurcsányi R E, Tóth K, Lindner E
Institute of General and Analytical Chemistry, Budapest University of Technology and Economics, Hungary.
Anal Chem. 2001 Sep 1;73(17):4249-53. doi: 10.1021/ac010094a.
Minor ion fluxes across ion-selective membranes bias submicromolar activity measurements with conventional ion-selective electrodes. When ion fluxes are balanced, the lower limit of detection is expected to be dramatically improved. As proof of principle, the flux of lead ions across an ETH 5435 ionophore-based lead-selective membrane was gradually compensated by applying a few nanoamperes of galvanostatic current. When the opposite ion fluxes were matched, and the undesirable leaching of primary ions was eliminated, Nernstian response down to 3 x 10(-12) M was achieved.
穿过离子选择膜的微量离子通量会使传统离子选择电极对亚微摩尔活性的测量产生偏差。当离子通量达到平衡时，检测下限有望得到显著改善。作为原理验证，通过施加几纳安的恒电流，逐渐补偿了铅离子穿过基于ETH 5435离子载体的铅选择膜的通量。当相反的离子通量相匹配，并且消除了主要离子的不良浸出时，实现了低至3×10⁻¹² M的能斯特响应。
