Université de Pau et des Pays de l'Adour/CNRS, LCABIE, UMR 5254 IPREM 2 Avenue P. Angot, 64053 Pau Cedex 9, France.
Anal Chim Acta. 2011 Mar 4;688(2):156-62. doi: 10.1016/j.aca.2010.12.034. Epub 2011 Jan 13.
The objective of this study was to exploit the advantages of stripping chronopotentiometry (SCP) and stripping chronopotentiometry at scanned deposition potential (SSCP) for trace metal speciation analyses by using thin-film mercury screen-printed electrodes (TMF-SPE). At first, the SCP parameters were optimised for TMF-SPE, in order to reach the complete depletion regime. It has been shown that a stripping current higher than or equal to 10 μA allows this regime to be attained without removing oxygen from the solution. Then, these analytical conditions were used for the construction of SSCP curves for Cd-PDCA and Cd-NTA. When the concentration of free ligand in solution was known, the knowledge of the model describing the SSCP curves in absence and presence of a complex and the use of an effective fitting tool enabled estimating the stability constant and the rate constants for complexation. Further studies with complexes of restricted mobility are however necessary to assess the usefulness of this procedure to also estimate the diffusion coefficient of the complexes. Besides, this study showed that this approach was valid even when ligands were not in excess at the electrode during stripping.
本研究旨在利用薄膜汞丝网印刷电极（TMF-SPE），通过剥离计时电位法（SCP）和扫描沉积电位下的剥离计时电位法（SSCP）的优势，实现痕量金属形态分析。首先，优化了 SCP 参数，以达到完全耗尽的状态。结果表明，只要剥离电流高于或等于 10μA，就可以在不从溶液中去除氧的情况下达到此状态。然后，使用这些分析条件构建了 Cd-PDCA 和 Cd-NTA 的 SSCP 曲线。当溶液中游离配体的浓度已知时，了解描述 SSCP 曲线在不存在和存在络合物时的模型，并使用有效的拟合工具，可以估计络合的稳定常数和速率常数。然而，还需要对具有受限迁移率的络合物进行进一步的研究，以评估该程序还可用于估计络合物扩散系数的有用性。此外，本研究表明，即使在剥离过程中电极上的配体没有过量，这种方法也是有效的。
