Journal article
Detection Limits of Thin Layer Coulometry with lonophore Based Ion-Selective Membranes
Analytical Chemistry, Vol.84(18), pp.8038-8044
2012
Abstract
We report here on a significant improvement in lowering the low detection limit of thin layer coulometric sensors based on liquid ion-selective membranes, using a potassium-selective system as a model example. Various possible processes that may result in an elevated residual current reading after electrolysis were eliminated. Self-dissolution of AgCl on the Ag/AgCl inner element may result in a residual ion flux that could adversely affect the lower detection limit. It was here replaced with an Ag/AgI inner pseudoreference electrode where the self-dissolution equilibrium is largely suppressed. Possible residual currents originating from a direct contact between inner element and ion-selective membranes were eliminated by introducing an inert PVDF separator of 50 mu m diameter that was coiled around the inner element by a custom-made instrument. Finally, the influence of electrolyte fluxes from the outer solution across the membrane into the sample was evaluated by altering its lipophilic nature and reducing its concentration. It was found that this last effect is most likely responsible for the observed residual current for the potassium-selective membranes studied here. For the optimized conditions, the calibration curves demonstrated a near zero intercept, thereby paving the way to the coulometric calibration-free sensing of ionic species. A linear calibration curve for the coulometric cell with valinomycin potassium-selective membrane was obtained in the range of 100 nM to 10 mu M potassium in the presence of a 10 mu M sodium background. In the presence of a higher (100 mu M) concentration of sodium, a reliable detection of 1-100 mu M of potassium was achieved.
Details
- Title
- Detection Limits of Thin Layer Coulometry with lonophore Based Ion-Selective Membranes
- Authors
- A Shvarev (Author) - University of Geneva, SwitzerlandB Neel (Author) - University of Geneva, SwitzerlandEric Bakker (Author) - University of Geneva, Switzerland
- Publication details
- Analytical Chemistry, Vol.84(18), pp.8038-8044
- Publisher
- American Chemical Society
- Date published
- 2012
- DOI
- 10.1021/ac301940n
- ISSN
- 0003-2700
- Organisation Unit
- University of the Sunshine Coast, Queensland
- Language
- English
- Record Identifier
- 99450218702621
- Output Type
- Journal article
Metrics
4 File views/ downloads
332 Record Views
InCites Highlights
These are selected metrics from InCites Benchmarking & Analytics tool, related to this output
- Web Of Science research areas
- Chemistry, Analytical