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Chapter 8 -- 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 Reference 3000
potentiostat/cell system. This list is not in any particular order. Any or all of these steps may help.
Slow down the potentiostat. The Reference 3000 has five control amplifier speed settings, which can
•
be selected in software. Slower settings are generally more stable.
Increase the Reference 3000's I/E stability setting. The Reference 3000 includes three capacitors that
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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 Luggin capillaries. If you do have a Luggin capillary, make sure that the capillary's
contents are as conductive as possible.
Add a capacitively coupled low impedance reference element in parallel with your existing reference
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electrode. The classic fast combination reference electrode is a platinum wire and a junction isolated
SCE. See Figure 8-1. 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 8-1
Fast Combination Reference Electrode
White
Cell Lead
SCE
Electrolyte
8 - 2
100 pF to 10 nF
Platinum
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