Antec Scientific VT-03, Руководство пользователя

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CHAPTER 1 The electrochemical flow cell 5
after starting up may be expected. We have so much confidence in our flow
cell that we warrant the glassy carbon flow cell for a period of 5 years.
Three-electrode configuration
In the VT-03 flow cell a three-electrode configuration is used (Fig. 2). The
working potential is set between the working electrode (WE) and the auxiliary
electrode (AUX). The AUX is kept at a precisely defined reference electrode
(REF) potential by means of the so-called voltage clamp. This is an electronic
feed back circuit that compensates for polarisation effects at the electrodes.
At the WE, which is kept at virtual ground, the electrochemical reaction takes
place, i.e. electrons are transferred at the WE. This results in an electrical
current to the I/E converter, which is a special type of operational amplifier.
The output voltage can be measured by an integrator or recorder.
Fig. 2. Schematic representation of an electrochemical cell with a three-
electrode configuration.
Essentially, for the oxidation or reduction reaction it would be sufficient to use
only two electrodes. However, the three-electrode configuration has several
advantages over a two-electrode configuration.
If the working potential would be applied only over an AUX versus the WE
(without REF), the working potential would continuously change due to
polarisation effects at the electrodes, resulting in highly unstable working
conditions.