How much analyte is removed from the electrode in Stripping ChronoPotentiometry? The depletion factor
Several electroanalytical techniques (such as Absence of Gradients and Nernstian Equilibrium Stripping, AGNES) need to quantify the amount of reduced analyte (M0) pre-concentrated in a mercury electrode. Among the used means for this quantification, Stripping ChronoPotentiometry, SCP, also known as...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universitat de Lleida (UdL) |
| Repositorio: | Repositori Obert UdL |
| OAI Identifier: | oai:repositori.udl.cat:10459.1/467508 |
| Acceso en línea: | https://doi.org/10.1016/j.jelechem.2024.118508 https://hdl.handle.net/10459.1/467508 |
| Access Level: | acceso abierto |
| Palabra clave: | PSA Mathematical model HMDE |
| Sumario: | Several electroanalytical techniques (such as Absence of Gradients and Nernstian Equilibrium Stripping, AGNES) need to quantify the amount of reduced analyte (M0) pre-concentrated in a mercury electrode. Among the used means for this quantification, Stripping ChronoPotentiometry, SCP, also known as Potentiometric Stripping Analysis (PSA), yields the time (τ) during which a constant total stripping current can progressively empty M0 from the electrode. The depletion factor (fd) is defined as the fraction of the total analyte that is depleted while the attainment of the constant total stripping current is possible. Full depletion only corresponds to the limiting case fd = 1. For (hemi)spherical electrodes, an analytical expression for fd is derived, which depends on the transition time τ, the electrode radius and the diffusion coefficient (but not explicitly on the total stripping current or the total charge). The theoretical expectations have been experimentally checked here with the Hanging Mercury Drop Electrode (HMDE) and the Thin Mercury Film Rotating Disc Electrode (TMF-RDE) for zinc and indium as analyte metals. In the case of the smallest drop in HMDE, for accurate total charge determinations, it is recommended to work with transition times longer than 5 s. In HMDE drops, the direct use of short transition times as analytical signals directly proportional to the free metal ion concentrations (in AGNES) might be inaccurate. Computing the charge with the depletion factor would be essential in such cases. |
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