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20 eDAQ Potentiostats
this control changes so as to limit the range over which the applied
current can be set,
Figure 5–7, page 68 .
Remember Potential
Check the box to remember the value of the
applied potential when the Potentiostat control window, Figure 2–7,
page 12 , is closed. (The potential value is transferred to the Stimulator
baseline control, Figure 5–2, page 63 ).
Maintenance
The Potentiostat will not require maintenance during daily operation.
However, you should periodically check the instrument for optimum
results by switching to potentiostat mode (with iR Compensation off) and
applying a known potential, E, to the Dummy Cell and checking that
the resulting current signal value, I, is in accordance with Ohm’s law:
I = E/R
where R is the resistance, and is 100 kohm (EA163) or1 Mohm
(EA161) for the dummy cell. Thus a signal of 10 μA (EA163) or 1 μA
(EA161) should be obtained when a potential of 1 V is applied. Try
several different potentials and make sure an appropriate current signal
is observed in each case.
If this test produces the expected results then your Potentiostat is likely to
be functioning correctly. Next use the Potentiostat in Real Cell mode to
check the electrode cables by attaching them to a resistor (usually a
resistor of 10
3
–10
8
ohm is ideal) with the working electrode lead on
one side of the resistor and the auxiliary and reference leads connected
to the other. If the current signal does not obey Ohm’s law, then it is
likely that the electrode leads have become damaged.
However, if both the Dummy Cell and Real Cell tests produce the
expected results, but you are still experiencing difficulties with your
experiments, then check the electrodes (reference electrodes, in
particular, tend to become clogged or dry out with age), and the
design and condition of the reaction vessel, and any salt bridges that
you are using.