Journal article
Backside calibration chronopotentiometry: Using current to perform ion measurements by zeroing the transmembrane ion flux
Analytical Chemistry, Vol.80(19), pp.7516-7523
2008
Abstract
A recent new direction in ion-selective electrode (ISE) research utilizes a stir effect to indicate the disappearance of an ion concentration gradient across a thin ion-selective membrane. This zeroing experiment allows one to evaluate the equilibrium relationship between front and backside solutions contacting the membrane by varying the backside solution composition. This method is attractive since the absolute potential during the measurement is not required, thus avoiding standard recalibrations from the sample solution and a careful control of the reference electrode potential. We report here on a new concept to alleviate the need to continuously vary the composition of the backside solution. Instead, transmembrane ion fluxes are counterbalanced at an imposed critical current. A theoretical model illustrates the relationship between the magnitude of this critical current and the concentration of analyte and countertransporting ions and is found to correspond well with experimental results. The approach is demonstrated with lead(II)-selective membranes and protons as dominating interference ions, and the concentration of Pb2+ was successfully measured in tap water samples. The principle was further evaluated with calcium-selective membranes and magnesium as counterdiffusing species, with good results. Advantages and limitations arising from the kinetic nature of the perturbation technique are discussed.
Details
- Title
- Backside calibration chronopotentiometry: Using current to perform ion measurements by zeroing the transmembrane ion flux
- Authors
- Y Xu (Author) - Purdue University, United StatesW Ngeontae (Author) - Purdue University, United StatesE Pretsch (Author) - ETH Zu¨rich, SwitzerlandEric Bakker (Author) - Curtin University of Technology
- Publication details
- Analytical Chemistry, Vol.80(19), pp.7516-7523
- Publisher
- American Chemical Society
- Date published
- 2008
- DOI
- 10.1021/ac800774e
- ISSN
- 0003-2700
- Copyright note
- Copyright © 2008 American Chemical Society. The author's accepted version is reproduced here in accordance with the publisher's copyright policy.
- Organisation Unit
- University of the Sunshine Coast, Queensland
- Language
- English
- Record Identifier
- 99450376902621
- Output Type
- Journal article
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- Domestic collaboration
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- Web Of Science research areas
- Chemistry, Analytical