Department of Chemistry/CICECO, University of Aveiro, 3810-193 Aveiro, Portugal.
Talanta. 2010 Mar 15;80(5):1881-7. doi: 10.1016/j.talanta.2009.10.038. Epub 2009 Oct 24.
In the present work, the applicability of thin mercury film on a rotating disk electrode (TMF-RDE), to assess the free metal ion concentration by the absence of gradients and Nernstian equilibrium stripping (AGNES), is evaluated. The thickness of the mercury film and several AGNES parameters has been optimized. A nominal 16 nm film is chosen due to the higher signal (faradaic current) relative to the value of the noise (capacitive current). Due to the smaller volume to area ratio, the deposition time needed to reach a certain preconcentration factor (Y) is much shorter than in larger electrodes, like the HMDE. The limit of detection (3 sigma) for lead(II) is 7.4 x 10(-9)M and 7.2 x 10(-8)M for a Y of 5000 (deposition time of 150 s) and 1000 (deposition time of 100 s), respectively. A specific mathematical treatment is developed in order to subtract a corrected blank taking into account the degradation of the thin film (presumably, falling down of drops). The couple TMF-RDE/AGNES is successfully applied for speciation purposes in the systems Pb(II)-latex nanospheres and Pb(II)-IDA (iminodiacetic acid), where the stability constants calculated for both systems agree with values reported in the literature.
在本工作中，评估了在旋转圆盘电极（TMF-RDE）上使用薄汞膜来评估自由金属离子浓度的适用性，通过不存在梯度和能斯特平衡剥离（AGNES）。优化了汞膜的厚度和几个 AGNES 参数。由于法拉第电流相对于噪声（电容电流）的值更高，因此选择了标称的 16nm 薄膜。由于较小的体积与面积比，达到一定预浓缩因子（Y）所需的沉积时间比在更大的电极（如 HMDE）中要短得多。对于 Y 值为 5000（沉积时间为 150s）和 1000（沉积时间为 100s），铅（II）的检测限（3sigma）分别为 7.4x10(-9)M 和 7.2x10(-8)M。为了扣除由于薄膜降解（可能是液滴掉落）而产生的修正空白，开发了一种特殊的数学处理方法。TMF-RDE/AGNES 偶联成功地应用于 Pb(II)-胶乳纳米球和 Pb(II)-IDA（亚氨基二乙酸）体系的形态分析，对于这两个体系，计算得到的稳定常数与文献报道的值一致。
