I am working with a Ag/AgCl reference electrode for CV. Some how due to leakage in the electrode mine reference electrode was dried up completely. I want to check whether is it working or not. How shall I proceed with the standardization of Ag/AgCl electrode? I am using this electrode for CV analysis of organic compounds.
Which solution I shall fill in?
Also I have seen some buff coloured solid substance in the cell what is it ? Shall I need to remove that, it has any enterferece on CV analysis, please help...
Dear Suryapratap,
many thanks for sharing this interesting technical problem with the RG community. It is well known that Ag/AgCl reference electrodes are easily ruined by drying. My suggestion would be to ask your boss to buy you a new one.
Good luck with your experiments and best wishes!
Many years ago, when I needed in my work a miniature reference electrode for CV measurements in microcell (one drop of solution), Prof. Barry Lever asked me why I didn't want to use a silver wire soaked in hydrochloric acid solution? :) And you know it really works!
The Ag/AgCl electrode normally has an internal solution with KCl in high concentration but saturated with Ag+. You should use the same KCl concentration as before. If you don't know the concentration I advise you to choose between 1,0 mol/L and saturated KCl (~4,0 mol/L). After preparing your KCl solution, you can drip a drop of an AgNO3 solution in the KCl solution and stir it. You can let the AgCl precipitate rest and collect the supernatant solution, which is saturated with Ag+, or filter the solution, whatever you choose. Then, you can fill your electrode with it. However, don't use the electrode immediately since you must wait for the equilibration time. I don't know the time by heart but I'm sure you can use it after a couple of hours of rest.
Ademario Junior, thank you for you reply sir
For organic compounds CV measureets I need to prepare the internal standard in Acetonitrile (KCl). And the solubility of KCl is poor in acetonitrile. In that case how should I determine the concentration of internal standard solution?
Suryapratap Sharma , do you have the name of the brand and the model of your reference electrode? I have been working for some time with some kinds of reference electrodes and yours could be different. I would be pleased to help find the solution, but I need more information.
Using a water electrode for measurements in non-aqueous solution introduces an undefined variable and an unmeasurable liquid potential jump in the cell, which is influenced by both solvent and ionic strength. Contamination of the non-aqueous solvent solution with water is another problem. In addition, the potentials measured in different solvents are not directly comparable, so it is not informative to refer to an aqueous electrode when making measurements in an organic solvent.
Ademario Junior sir
I am working with Metrohm companies CV and electrode as well
For your reference I have attached the image of the cell also.
Suryapratap Sharma , this seems to be an Ag/AgCl electrode with a double junction. I reasoned it after seeing a more complete picture in the Metrohm website: https://www.environmental-expert.com/products/metrohm-model-60733100-ag-agcl-reference-electrodes-709874 . Thus, the most internal solution is a 3.0 mol/L KCl solution saturated with Ag+ as I described before and must be dealt with as I wrote. You must have a syringe to help you fill the solution through the correct hole. However, the most external solution can have a completely different constitution, should be filled just prior to usage and emptied after you finish your measurements using another syringe. The double junction electrode must be stored only with the most internal solution in place and withouth the most external solution. The latter must be filled only when you are about to use the electrode. You can use LiCl in the composition of the external solution. This salt has a higher solubility in organic solvents and even in acetonitrile: https://en.wikipedia.org/wiki/Lithium_chloride_(data_page) . Thus, I think it could be used this way. Nevertheless, I must say that I never worked with potentiometric measurements in organic solvents, although I am aware of the usage of (LiCl/organic solvent) for this aim. I am not sure whether the interface between the aqueous solution and the organic solution will work with any solvent since I have no experience with this kind of interface - I employed double junction to protect the reference electrode when the external solution is aggressive to the electrode or when the internal electrode solution can react with the solution I want to measure.
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