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Chapter 4 -- Stability in Potentiostat Mode -- Improving Potentiostat Stability
Improving Potentiostat Stability
There are a number of things that you can do to improve an unstable or marginally stable PCI4 potentiostat/cell
system. This list is not in any particular order. Any or all of these steps may help.
Slow down the potentiostat. The PCI4 has 4 control amplifier speed settings which can be selected
•
in software. Slower settings are generally more stable.
Increase the PCI4's I/E stability setting. The PCI4 includes 2 capacitors that can be paralleled with its
•
I/E converter resistors. These capacitors are connected to relays that are under software control.
Contact your local Gamry Instruments' representative for more information concerning changes in
these settings.
Lower the reference electrode impedance. Make sure that you don't have a clogged reference
•
electrode junction. Avoid asbestos fiber reference electrodes and double junction electrodes. Avoid
small diameter Lugin capillaries. If you do have a Lugin capillary, make sure that the capillaries'
contents are as conductive as possible.
Add a capacitively coupled low impedance reference element in parallel with your existing reference
•
electrode. The classic fast combination reference electrode is a platinum wire and a junction isolated
SCE. See Figure 4-1. The capacitor insures that DC potential comes from the SCE and AC potential
from the platinum wire. The capacitor value is generally determined by trial and error.
Figure 4-1
Fast Combination Reference Electrode
White
Cell Lead
SCE
Electrolyte
4-2
100 pF to 10 nF
Platinum
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