SYMPOSIA PAPER Published: 01 January 1993
STP18064S

The Effect of Parasitic Conduction Pathways on EIS Measurements in Low Conductivity Media

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Artifacts are ubiquitous to electrochemical impedance measurements at sufficiently high frequency. These artifacts, which are exacerbated by low conductivity solutions, can arise from the measurement electronics, the reference electrode, the electrical leads, or the electrochemical cell, or a combination thereof. This study has systematically examined the factors that may contribute to the occurrence of artifacts in low conductivity media. The frequency regime over which artifacts exist was identified for steel in lake water. The value and occurrence of the solution resistance was identified by adjusting the conductivity and comparing the results with calculated values. Possible contributions from the frequency response analyzer, potentiostat, reference electrode, and cell geometry were studied using a series of test resistors. The major contributors to artifacts appear to arise from the potentiostat and associated leads, and the ratio of the resistances between the working and reference and the reference and counter electrodes in the electrochemical cell. The problem of fitting complex spectra was approached by combining nodal analysis with simplex fitting. A model was determined that accurately reproduces the spectra for a set of current measuring resistors used in the voltage-drop configuration for two electrode measurements using a particular make of potentiostat.

Author Information

Stewart, KC
Center for Electrochemical Science and Engineering, University of Virginia, Charlottesville, VA
Kolman, DG
Center for Electrochemical Science and Engineering, University of Virginia, Charlottesville, VA
Taylor, SR
Center for Electrochemical Science and Engineering, University of Virginia, Charlottesville, VA
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Details
Developed by Committee: G01
Pages: 73–93
DOI: 10.1520/STP18064S
ISBN-EB: 978-0-8031-5240-3
ISBN-13: 978-0-8031-1861-4