Measure Reference Electrode Impedance

Measure Reference Electrode Impedance allows you to measure the impedance (resistance) of the reference electrode in an electrochemical cell. It uses a specialized version of EIS to measure the impedance. You do not need EIS authorization. Gamry Instruments’ website has an application note describing this in some detail.

Run this utility by selecting Experiment > Utilities > Measure Reference Electrode Impedance on the Framework™ menu bar. Follow the instructions in the resulting dialog boxes.

This test actually measures the impedance between the reference and counter electrodes. It assumes that most of this impedance can be attributed to the resistance of the reference electrode and the solution in the Luggin capillary (if one is present). Bulk-solution resistance between the tip of the reference electrode (or Luggin capillary) is assumed to be negligible.

Reference-electrode impedance is critical for proper control of an electrochemical system. Excessive reference impedance can cause phase-shift in EIS experiments, can cause ringing and noise in DC experiments, and in extreme cases will cause oscillation of the potentiostat.

In general, Gamry’s potentiostats do not oscillate when the reference impedance is less than 10 kΩ. To avoid excess noise and ringing following a voltage step, keep the reference impedance below 2000 Ω.

The following problems are known to cause high impedance in reference electrodes:

• Air bubbles. There must be an unbroken path in the solution between the internal reference element and the tip of the reference electrode.
• A small-diameter Luggin capillary.
• Low electrolyte concentration in the Luggin capillary or reference electrode
• Poor porosity in any frits used for reference isolation
• Clogged frits. Crystals can form within the frit when the cell electrolyte forms an insoluble salt with the KCl that usually fills reference electrodes. Be careful when you use perchlorate electrolytes, for KClO₄ has low solubility. Organic material adsorbing on frits can also cause clogging. Proteins adsorb strongly on fritted glass.