Electrochemistry: Stability test of reference electrode

[shay]

Dear subscribers

Re: Stability test of reference electrode

One of the important properties of reference electrode is its stability during measurements or potential scan. How one can check its stability in a certain electrochemical system?

One of the way is to use internal reference, for example ferrocene. However I am afraid that it will be involve in some chemical reaction with my electrolyte system as I replace it each time (I am doing some screening). In some cases the ferrocene may not be dissolved properly.

Are there any other methods that I can use to test the reference stability?

 

[GCT]

Are you utilizing a potentiostat? Please describe your experiment as well as the equipment.

 

[chemisttree]

If you are worried about ferrocene not dissolving, make sure that it does dissolve or that it is dissolved in the matrix electrolye before you add it to your sample. Do this with the matrix electrolyte with and without your analyte to see if ferrocene is compatible. If you are worried about ferrocene's compatibility with your analyte, you need to analyze your sample analyte with and without ferrocene and do so over several time periods to note any change. You might also add ferrocene to your analyte and let it set for some time and then filter it through a very fine filter (.2 micron, for example) to see if any solids are produced. Do this test for pure matrix and analyte + matrix as well to ensure that your system is stable under the measurement conditions (air sensitive, CO2 sensitive, etc...).

good luck with it.

 

[shay]

Thank you Chemisttree and GCT.

As for GCT, my system includes: V3 potentiostate of Princeton Applied Research, the electrolytes is 0.1 NaNO3 in water (However I wish to move to alcohols and also to non-polar solvents with very low conductivity). The reference electrode is Ag/AgCl in sat'd NaCl. The WE can be change. Now I am focusing on Al.

How I can be sure that my reference is stable in different systems. Maybe it is unstable in non-polar solvents?

 

[GCT]

I've used the silver chloride as a reference electrode however in 3 M KCl - from what I remember you want to keep the solution in the reference electrode relatively similar to that in the solution with respect to the chemical species although this probably is not a big factor; I've had no problems with the silver chloride electrode however some variations in the potentiostat readings can actually be due to dissolved oxygen and if aggregates are present in the solution they can also take up charge and contribute to bad readings.

For instance I had Resorufin aggregates which took up charge to become resorufin which was the actual analyte being titrated; since the potentiostat reading is proportional to the ratio of the redox species of resorufin the aggregate contributed to strange readings.

 

[chemisttree]

Thank you Chemisttree and GCT.

As for GCT, my system includes: V3 potentiostate of Princeton Applied Research, the electrolytes is 0.1 NaNO3 in water (However I wish to move to alcohols and also to non-polar solvents with very low conductivity). The reference electrode is Ag/AgCl in sat'd NaCl. The WE can be change. Now I am focusing on Al.

Do not use Al in an alcoholic solvent. Use gold plating or platinum only.