We are trying to determine the conductivity of organic solutions (acetonitrile solvent). EIS gives negative solution resistance for these species. We are using a conductivity cell with two platinum electrodes.
dear Alex Gupta;
you can determine conductivities by extrapolation for more details can read the following references;
Article Electrical conductivity of electrolyte solutions in organic solvents—I
Article THE EXTRAPOLATION OF CONDUCTIVITY DATA TO ZERO CONCENTRATION...
Hello Alex Gupta
When you say you obtained negative resistance using EIS, can you give us more details about your experiments : How did you plot your graphs? How did you determine the resistance etc? Then it would be easier for me to help.
Best regards,
Marie B.
Hi Marie,
Thanks for your response. We used an electrochemical cell in two-electrode configuration (platinum electrodes). We took EIS spectra from 100 kHz to 0.1 Hz at 5 mVRMS amplitude with 0 V base DC potential difference between the electrodes and then plotted the spectra in both Nyquist and Bode representations. See the attached image of raw data as displayed in NOVA software. We truncated the data after around 1500 Hz (after the first time constant) and then fit the data to a R-RC circuit model. We took the x-intercept of the fit at high frequency as the solution resistance. This technique gave us non-negative values of solution resistance when the solvent contained charged organic solutes, but we see negative values when working with uncharged organic species in the same solvent.
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