Dissolved Oxygen Measurement

The measurement of dissolved oxygen is important for determining the health of our natural waterways and their ability to support life.

Historically tests have been performed with expensive Meters and Polarographic sensors which were awkward to set up and required a specialist meter. Our Galvanic DO probe is compatible with our pH/ION meter and facilitates the measurement of several environmental parameters on one simple portable instrument.


The Galvanic Dissolved Oxygen Probe 

The E8020 Galvanic Dissolved Oxygen (DO) Electrode is for use with the QP459 Portable ION/Dissolved Oxygen Meter.

Galvanic Dissolved Oxygen Electrodes have a significant advantage over the traditional Polarographic (Clark) cells in that they are
maintenance free and have a mV output enabling them to be used on pH meters with mV scales or direct reading meters such as
the QP459 Dissolved Oxygen and Ion meter.

The E020 Galvanic electrode has Zinc Anode and Platinum Cathode with a large cell potential between them, meaning that one
metal wants to give up electrons while the other wants to gain electrons. The resultant potential is strong enough to cause electrons
to flow from the Anode to the Cathode.

The electrode has an inert gas permeable membrane allowing Oxygen to permeate into the cell and oxidise the anode forming a
metal hydroxide. The degree of oxidation is directly proportional to the dissolved oxygen concentration.

This construction has many advantages including maintenance free operation with a non-replaceable rugged membrane.

 Operation and measurement

The E8020 Galvanic Dissolved Oxygen electrode should be calibrated at both Zero % Oxygen and at 100% saturation.
The 0% Oxygen solution is a 5% Sodium Sulphite in deionized water. The second calibration point can be done by agitating the
probe in air or by running the tip under a fastflowing tap.

Once calibrated the probe should remain calibrated for several days. It is simple to check this by reading the air and checking that
100% is still displayed.

The saturation will however vary with Atmospheric pressure and temperature

 Storage and maintenance.

Before use the electrode tip should be rinsed in deionized water (tap water is also OK) prior to calibration and measurement. It is
particularly important after the Zero-point calibration.

After use rinse the probe with water and replace the protective cap. The cap is supplied with a KCl (Potassium Chloride solution). If this solution is lost, then storing
it with water is satisfactory.

Expected Lifetime
Eventually build up of Metal oxide precipitate or sample exposure may block the permeable membrane leading to probe failure. This
depends on the sample type and frequency of use. The probe does contain a power source which should last for 12-24 months.