anode and a silver cathode. In an alkaline electrolyte (e.g. 1 M KOH) the following reaction will occur
if a reducible species is present
If the electrodes are surrounded by a semipermeable membrane through which only oxygen can diffuse
from the external solution, reduction of oxygen will take place.
The current flowing in the cell will depend upon the rate of diffusion of oxygen to the electrode surface
and ultimately on the concentration of oxygen in the external solution. The construction of such an
electrode is shown in Figure 6.14.
Figure 6.14
Construction of an EIL temperature
compensated oxygen electrode
(from EIL advertising material).Applications of the Dissolved Oxygen Electrode
Electrodes are capable of measurement at around the 1 ppm level. They are simple, robust and portable.
As such there is considerable potential for their employment in ecological studies and they can provide
constant monitoring of dissolved oxygen, e.g. in river waters. The potential for their employment in
monitoring industrial liquors is clear, as is their applications in biological investigations of oxygen
transport.
Principles of Enzyme Sensors
The biochemical oxidation of organic molecules is accomplished by enzymes known as oxidases.
Specific oxidases exist for the oxidation of each