As part of support of support of ZP's products this week we are trouble shooting 501 screen printed carbon electrodes.
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Key Points from the Video:
- User's Setup & Problem:
Using ZP 501 screen-printed electrodes (circular carbon electrodes with a large counter electrode).
Running CV with 5 mM ferricyanide in ~0.05 M KCl (diluted from 0.1 M KCl).
Observing distorted CV curves with unusually high currents (~100 µA vs. expected ~25 µA).
Suspecting a bad connection or adapter issue.
Speaker’s Analysis:
The peak currents are ~4x higher than expected.
Suggests the working and counter electrodes may be swapped (since the counter electrode is large, swapping would increase the effective working electrode area, leading to higher currents).
IR drop (voltage drop due to solution resistance) worsens with higher currents, distorting the CV.
Demonstration & Fix:
The speaker runs a similar experiment with correct connections, getting expected currents (~25 µA).
Recommends checking electrode connections (working vs. counter).
Mentions that ZP potentiostats have foolproof connectors to prevent such issues.
Other Possible Factors:
Lower KCl concentration (0.05 M vs. 0.1 M) increases solution resistance.
- Electrode cleaning (using 0.01 M H₂SO₄) is good practice but not the root cause here.
Suggested Solutions:
Verify electrode connections (ensure working, counter, and reference are correctly assigned).
Check potentiostat setup (some devices auto-detect connections, reducing errors).
Use higher electrolyte concentration (0.1 M KCl) to minimize IR drop.
Ensure good contact between the connector and screen-printed electrodes.
Final Thought:
The distortion likely comes from miswired electrodes (working and counter swapped), not just a bad connection. Fixing this should normalize the CV shape and current magnitude.