Garay Fernando, Barbero Cesar A
INFIQC, Departamento de Físico Química, Fac. de Ciencias Químicas, UNC, Pab. Argentina, Ciudad Universitaria, 5000 Córdoba, Argentina.
Anal Chem. 2006 Oct 1;78(19):6733-9. doi: 10.1021/ac0603678.
The theoretical framework of a general model for the simulation of concentration profiles of electroactive and nonelectroactive species, driven by an electrochemical process under potentiostatic conditions, is presented. Based on this analysis, finite differences simulations are performed to calculate the actual profiles under different experimental conditions. Furthermore, the effect of experimental parameters (diffusion coefficients of the ions of the redox couple or the supporting electrolyte, charge of the different species, etc.) on the concentration profiles is also examined. The results obtained when low and high concentrations of supporting electrolyte are compared aid understanding of the effect of the electrolyte on the measurements. The presented model also underlines the role of supporting electrolyte species when nonspecific techniques are employed to measure the concentration changes produced by electroactive species. On the other hand, if a highly specific technique were used to detect changes in the concentration or concentration gradient of a given species, then it would be possible to estimate the respective profiles of the other species. The simulations suggest that techniques measuring concentration gradients are more sensitive to determining concentration changes than those involving a measurable linearly related to concentration.
本文提出了一个通用模型的理论框架，用于模拟在恒电位条件下由电化学过程驱动的电活性和非电活性物种的浓度分布。基于此分析，进行了有限差分模拟，以计算不同实验条件下的实际分布。此外，还研究了实验参数（氧化还原对离子或支持电解质的扩散系数、不同物种的电荷等）对浓度分布的影响。比较低浓度和高浓度支持电解质时获得的结果有助于理解电解质对测量的影响。所提出的模型还强调了在采用非特异性技术测量电活性物种产生的浓度变化时支持电解质物种的作用。另一方面，如果使用高度特异性的技术来检测给定物种的浓度或浓度梯度变化，那么就有可能估计其他物种的各自分布。模拟结果表明，测量浓度梯度的技术在确定浓度变化方面比那些涉及与浓度呈线性相关的可测量值的技术更敏感。
