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3.7
Cyclic Voltammetry
The Voltammetry mode is used to develop cyclic voltammograms. Cyclic
Voltammetry is similar to Integrated Amperometry in that a repeating potential vs.
time waveform is applied to the cell. It differs in that the Dionex ED50A output is
the cell current, which is continuously monitored and reported as in DC
Amperometry. The information gained by studying instantaneous cell current can
be useful for developing waveforms for Integrated Amperometry or to determine
potentials for DC Amperometry.
With the pump on, and mobile phase and analyte flowing through the
amperometry cell, results are similar to those obtained by rotated disk
voltammetry in a standard beaker cell. With the flow off, rapid depletion of
analyte next to the working electrode is typical of thin-layer voltammetry.
3.7.1
Cyclic Voltammetry with the Dionex ED50A
To monitor cell current in the Voltammetry mode, connect the Dionex
ED50A analog output to a recording device.
1. Locate the
ED50A electronics chassis (see Figure 2-3 in this manual or the label
on the inside of the Dionex ED50A front door).
2. Connect pin 1 to the (-) contact of the Y input on the XY plotter.
Connect pin 2 to the (+) contact of the Y input.
3. Connect pin 7 (EC Drive) to the (+) contact of the X input. Connect
pin 10 (Ground) to the (-) contact of the X input.
4. Switch the Dionex ED50A to the Voltammetry mode.
5. Program the waveform (see Section 3.7.2). For example, here are
some typical cyclic voltammetry waveforms:
Glassy carbon electrodes: 0 to 1 V and back to 0
Gold electrodes: -0.5 to 0.7 V and back to -0.5
NOTE Waveform programming can be difficult at first.
Doc. 065551-01 6/13
3 • Operation and Maintenance
connectors on the SCR card in the Dionex
RECORDER
The slowest rate allowed is 0.1 V/s. A beep sounds if
this rule is violated. Thermo Fisher Scientific
recommends practicing with a Dionex ED50A
validation cell (P/N 049928), to avoid subjecting the
working electrode to extreme changes while
3-11
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