60 DECADE user manual, edition 9
electrons are transferred at the WE resulting in an electrical current that is
amplified by the controller.
Hydrodynamic and scanning voltammogram
A
hydrodynamic
voltammogram is constructed when the pure analyte is not
available and separation over an analytical column is required. Furthermore,
under real chromatographic conditions reliable information about the S/N ratio
is obtained
In case of metal working electrodes it is also advisable to use a
hydrodynamic
voltammogram. On the metal working electrode an oxide layer is formed
which affects the electrochemical reaction and makes the interpretation of a
scanning voltammogram difficult.
Fig. 23. Hydrodynamic voltammogram of nor epinephrine (A) at a glassy
carbon working electrode, and the current of the baseline (B). At E
1
the
electrochemical signal becomes diffusion limited.
An alternative for the chromatographic construction of an I/E relationship is
the application of scanning voltammetry. The working potential runs between
two pre-set values and the current is measured while the analyte is
continuously flushed through the flow cell.
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