Preparation:
1. Remove the protective bottle from the sensing element and save it for storage.
2. Clean any salt deposits from the exterior of the electrode by rinsing with distilled water, dry with a lint-free tissue.
3. Connect the electrode to the Analyser or meter.

Direct Measurements:
Direct oxidation-reduction potential (ORP) measurements can be used to determine the oxidizing or reducing capability of a solution and are commonly made in polluted streams, chlorinated waters, industrial wastewaters and other water samples.
1. Prepare the electrode according to the Electrode Preparation section.
2. Set the Analyser or meter to ORP or mV measurement mode.
3. Place the electrode into the sample solution.
4. When the reading stabilizes, record the displayed mV potential and temperature.

Maintenance:
1. Between measurements, thoroughly rinse the electrode with distilled water, dry with a lint-free tissue.
2. Keep in soaking solution bottle for Long-term Storage (over one day)
3. General cleaning: For non-organic contamination, soak the electrode in 0.1 M HCl for 10 minutes, rinse with distilled water.
For organic or oily contamination, soak the electrode for 15 minutes in a 1:10 dilution of household washing liquid or a 0.1 to 0.5% liquid detergent solution mixed with hot water, stirred the solution at a moderate to fast rate.
After one of the above cleaning methods, soak the electrode in pH4 buffer solution for at least 8 hours before measurement. Rinse with distilled water before use.

Checking Electrode Operation:
Checking the electrode is necessary only when there is evidence of malfunction that cannot be traced to other causes. Set the Analyser or meter to ORP or mV measurement mode (at 25°C), immerse the electrode in pH7 solution (saturated with Quinhydrone), the stable reading (E1) should be 86±15 mV. Next immerse the electrode in pH4 solution (with Quinhydrone), take the stable reading (E2), E2-E1 should be > 165 mV.

Note: Platinum redox electrodes may give unstable readings in solutions that contain chromous, vanadous and titanous ions or other ions that are stronger reducing agents than hydrogen or platinum. Electrodes with an epoxy body should only be used in aqueous solutions. The ORP electrodes contain a Ag/AgCl) reference that may become clogged in solutions that contain silver complexing or binding agents such as TRIS, proteins and sulfides. Frequent cleaning may be required when measuring solutions that contain these agents. Proteins cause the additional problem of coating the electrode, so extra care should be taken to keep the electrode clean while measuring samples that contain proteins.

Page created by CCR 19 Sept. 2008