59
Optimization of the working potential
AZURA® Detector ECD 2.1 Instructions, V6685
9.5 Construction of a hydrodynamic
voltammogram
Before a hydrodynamic voltammogram can be obtained, the chroma-
tographic conditions should be optimized. Then the following steps are
taken:
1.
A solution of the analyte at a concentration between 1 - 100 µmol/L,
is prepared in mobile phase.
2.
The electrochemical detector is stabilized in the DC mode at a high
potential. After stabilization the background current is read from the
display of the detector (Icell) and the noise is measured.
3.
The run is started by injecting the compound. When at the high
working potential no signal is obtained, it may be concluded that the
compound is not electrochemically active. In such a case derivatiza-
tion of the compound may be an option.
4.
If a peak is measured, the working potential is decreased by 50 or
100 mV and step 2 to 4 is repeated until the lowest potential setting
5.
The peak heights and the background currents are plotted against
the working potential (Fig. 41).
The working potential which gives the best sensitivity is obtained by plot-
ting the signal-to-noise ratio against the working potential.
Fig. 46
Construction of a hydrodynamic voltammogram for norepinephrine.
Chromatograms are obtained at cell potentials ranging from 1.0 V
(back) to 0.4 V (front), with 100 mV steps.
Summary of Contents for Azura ECD 2.1
Page 1: ...HPLC Detector ECD 2 1 Instructions Document No V6685 ...
Page 32: ...28 ECD 2 1 controller AZURA Detector ECD 2 1 Instructions V6685 Pulse mode ...
Page 33: ...29 ECD 2 1 controller AZURA Detector ECD 2 1 Instructions V6685 Scan mode CONFIC menu ...
Page 34: ...30 ECD 2 1 controller AZURA Detector ECD 2 1 Instructions V6685 DIAG menu ...