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Troubleshooting Noise in an Electrochemical System with a Rotator DRK10039 (REV001 | JUN 2017)
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the counter (CTR) and reference (REF) leads of the cell cable. Finally, set up an electrolysis (chronoamperometry)
experiment with an applied potential of
1.5 𝑉𝑉
for
60 𝑠𝑠𝑠𝑠𝑠𝑠
. During the electrolysis, solid silver chloride is deposited on
the silver wire, forming a
𝐴𝐴𝐴𝐴 / 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴
wire. The freshly prepared
𝐴𝐴𝐴𝐴 / 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴
wire can be placed straight into a
100 𝑚𝑚𝑀𝑀 𝐾𝐾𝐴𝐴𝐴𝐴
electrolyte with no further preparation to test for noise in the electrochemical system. If the
𝐴𝐴𝐴𝐴 / 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴
wire electrode
eliminates the noise, the original reference electrode is defective and needs to be replaced.
INFO:
Information on how to construct a master reference electrode can be
found on our knowledgebase:
https://www.pineresearch.com/shop/knowledgebase/
Search “Document Index” and find related article DRP10031.
2.2 Cable Shielding and Length
Environmental noise can interfere with an electrochemical system through the cable that links the potentiostat to
the electrochemical cell. To reduce noise that arises through the cable, ensure that the cable is as short as possible
and/or that the cable is shielded. The Pine Research WaveNow and WaveDriver series potentiostats/bipotentiostats
include a cell cable where all signal lines are individually shielded. Additionally, the Pine Research WaveNow series
potentiostats may be connected to a compact voltammetry cell through a mini-USB style cable that have all signal
lines enclosed in a single shield.
The Pine Research CBP Bipotentiostat includes a shielded BNC cable for connecting to the reference electrode,
but the working electrode(s) and counter electrode connections are unshielded. However, the default unshielded
cables terminated with two banana plugs can be replaced with shielded BNC cables terminated with banana-
plug to BNC (female) adapters. The shield or the ground line of a shielded cable for the working or the counter
electrode can be connected to the chassis ground (a silver post) of the CBP biopotentiostat. However, the shield
for the reference electrode should not be connected to any other conductor. For example, it should not be
connected to the black banana socket (known as DC common) nor to the silver chassis ground of the CBP.
2.3 Checking Rotator Brush Contacts
The brush contacts to the rotator shaft complete the conductive path for the electrical signals to and from the
working electrodes in the electrochemical cell to the potentiostat. Electrical noise associated with the brush
contacts can be of mechanical or electromagnetic origins. If the frequency of the observed noise is proportional
to the rotator speed, then the noise is likely caused by mechanical factors. To inspect the rotator shaft and brush
contacts, open the clamshell doors on the rotator housing (see: Figure 1). The rotator shaft surface should be very
smooth and free of corrosion or defects. The surface of the brush contacts should be flat and smooth (when new)
or curved with a groove to match the rotating shaft (after use). The worn groove should align exactly with the
rotator shaft. If the alignment is not perfect, do not try to realign the groove by rotating the brush contact. This
method is inaccurate when done manually. A slightly misaligned groove with respect to the shaft can cause
squeaking and vibrations, which contribute to the recorded noise. If misalignment already occurred, remove the
brush contact and polish out the previous wear mark. Alternatively, the brush contact can be rotated
90°
with
respect to the wear mark, so that the new wear mark will be perpendicular to the old one. Rotating the brush
contact
90°
can eliminate the squeaking vibration. The concave groove of a brush contact can be removed by
Figure 1. Rotator Housing Closed and Open to Visualize Brush Contacts