9.3 Hydrodynamic and scanning voltammograms
9.3.1 Hydrodynamic voltammogram
A hydrodynamic voltammogram is constructed when the pure analyte is not available and
separation over an analytical column is required. Under real chromatographic conditions, reliable
information about the S/N ratio is obtained. The peak heights obtained from the sequence of
chromatograms are plotted against the working potential used. Also, the back-ground current (I-
cell) is plotted.
Figure 9–2: Hydrodynamic voltammogram of norepinephrine at a glassy carbon working
electrode (A) and the current of the baseline (B). At E1 the electrochemical signal
becomes diffusion limited.
9.3.2 Scanning voltammogram
An alternative for the chromatographic construction of an I/E relationship is the application of
scanning voltammetry. In a scanning voltammetry experiment, the working electrode potential is
ramped up and down between two preset potentials (E1 and E2), and the current is measured
while the analyte is continuously flushed through the flow cell. This is repeated as many times as
necessary. The rate of voltage change over time is defined as the scan rate (mV/s).
Figure 9–3: Scanning voltammetry potential waveform
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