Gamry Instruments Launches New Online Reference Electrode Conversion Calculator Gamry Instruments announced a new tool to help researchers get the most value from their data. Their new ‘Reference Electrode Conversion Calculator’ can be used to convert potentials recorded using one reference electrode into potentials recorded using a different reference electrode. This tool can be used Read more about Online Reference Electrode Conversion Calculator[…]
Care of Porous Glass Frits
Porous Glass is often used at the end of a reference electrode or a bridge tube to allow electrical, ionic conductivity between the bulk of the solution and the internal filling solution, while preventing large scale convective mixing of the solutions. Porous Glass, or “thirsty glass” is a porous glass with a fairly low leak rate.
The Porous Glass frits, however, are not immortal!
To preserve their useful lifetime, they should be kept wet. If they are allowed to dry out, solid crystals can clog the narrow pores and increase the electrical resistance. In extreme cases, the Porous Glass can crack upon drying out.
When not in use, the reference electrode or bridge tube can be stored with the Porous Glass frit immersed in distilled water. Diffusion through the Porous Glass is fairly slow, and the internal filling solution will not be diluted, even upon a few weeks of storage.
An alternative is to replace the small plastic cap that was in place when the reference electrode was shipped.
Replacing a Porous Glass Frit
My favorite My favorite reference electrode is the Ag/AgCl reference.electrode. Due to its simplicity, it is quite robust, and can be easily and effectively ‘revived’ if it should dry out. Moderately high temperatures ( 100 °C ) can be tolerated, as long as the AgCl does not completely dissolve and the construction materials are suitably Read more about Selecting a Reference Electrode[…]
Room temperature ionic liquids or simply ionic liquids (some even call them molten salts) can act as a great solvent for electrochemistry but they bring along a challenge of what to use for the reference electrode. Traditional saturated calomel or Ag/AgCl reference electrodes use water as a solvent which can cause trouble for ionic liquids. Read more about Reference Electrode for Ionic Liquids[…]
This Application Note presumes that you have a basic understanding of potentiostat operation. If you are not that knowledgeable concerning electrochemical instrumentation, please read Potentiostat Fundamentals before continuing. Experienced potentiostat users may skip the primer and read on.
It’s only natural that electrochemists concentrate on the working electrode. After all, reactions at the working electrode are what they study. However, the reference electrode shouldn’t be ignored. Its characteristics can greatly influence electrochemical measurements. In some cases, an apparently “good” reference electrode can cause a complete failure of the system.
For reliable reference electrode performance, you should assign a “Lab Master” and treat it very, very carefully so it can serve as a standard for your other reference electrodes. Never use the Lab Master in an actual experiment. The only purpose of the Lab Master is to serve as a check for the other reference electrodes. If a reference electrode is suspected to be bad, you can check the potential versus the Lab Master. You can do that with a voltmeter, or with your Gamry Potentiostat by running and open circuit potential. If the potential difference is less than 2-3 mV, it’s OK. If it’s higher than 5 mV, it needs to be refreshed or discarded.
Often we find a potential listed in the literature quoted against a different reference electrode than the one we favor, or we would like to convert the potential to a more commonly used reference electrode for publication. A student emailed me: “My experiments involve measuring the redox potential relative to a saturated Ag/AgCl reference electrode. Read more about Converting Potentials to Another Reference Electrode[…]
The following tables give the potentials of several commonly used reference electrodes. Various filling solutions are listed where data was available. Note that the nature and concentration of the filling solution can dramatically change the potential! When you look through the scientific literature, be sure the author has specified the filling solution! If you are Read more about Potentials of Common Reference Electrodes[…]