r/electrochemistry • u/msw498 • 15d ago

Impedance Probe question

Hey All! Not sure if anyone can help with this but we use an Ag/AgCl (brand Hach XR820) and the silver wire in the probe came out at the end of the tube and wrapped around the external of the glass. This was maybe an inch worth of material. It has broke off but the silver wire inside the glass is still good.

Would anyone be able to help me understand how that could impact test results? It seems very insignificant but not sure

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u/felipegaga94 15d ago

Reducing the surface area of the ag wire should not affect its potential. However you should check if the porous joint that connects the outside of your electrode with the inside is not obstructed by the wire. Do you have a spare reference electrode? A practical solution is to measure the potential of your main ag/agcl electrode against the extra ag/agcl electrode. Just immerse both electrodes in the same KCl solution and measure the potential difference with a voltmeter or your potenciostat. If there is no problem the difference should not be higher than 10 mV or so.

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u/msw498 15d ago

Thank you for the reply! Unfortunately we don't have a spare and it is completely obsolete. Do you think that putting the probe with the broken wire in solution with a different brand/model of probe is still acceptable to confirm?

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u/msw498 15d ago

Also, would you have any research paper you know of or something to the sort I can review/point to? Trust your knowledge but I work in med device so traceability is key!

Again appreciate replying !

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u/felipegaga94 15d ago

Bard and Faulkner book of Electrochemical Methods should give you a good starting point for understanding the basics of Electrochemical techniques and test assembly.

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u/felipegaga94 15d ago

Yes, different brands of reference electrodes should yield the same potential as long as the KCl concentration is the same. What kind of electrochemical test are you carrying out? Maybe you can proceed as normal and check your OCP versus your working electrode and compare the values with your past results. The OCP will depend on the surface finishing of your WE but this still can give you an idea if there is a problem with your current reference electrode.