ORP Electrode Cleaning

The following procedure will result in the removal of many common contaminants from the platinum ORP electrode. Fouling of the electrode can be deployment-specific, and some contaminants from polluted water may not be dissolved by this method. The use of other solvents and reagents may be possible, but they must be selected carefully so as not to damage the reference electrode or pH glass of the combination sensors nor to leach or dissolve the body of the probe itself. Consult YSI Technical Support before using cleaning methods other than those documented below. YSI recommends that the user perform the cleaning/reconditioning operation in the order indicated. Performance can be rechecked at the conclusion of each major section (A, B, and C), and the cleaning discontinued if, at that point, the performance problem has been corrected.

Procedure A

Soak the probe for 10-15 minutes in clean water containing a few drops of commercial dishwashing liquid.
Wipe the platinum button or ring by rubbing with a cotton swab soaked in the cleaning solution. CAUTION: Be certain not to damage the glass bulb of the combination sensor during this process. Any pressure on the glass bulb can cause breakage.
Rinse the probe in clean water, wipe with a cotton swab saturated with clean water, and then re-rinse with clean water.

Procedure B

Soak the probe for approximately 1-2 hours in up to a 1:1 dilution of commercially available chlorine bleach.
Rinse the probe with clean water and then soak for at least 1 hour in clean water to remove residual bleach from the reference junction. CAUTION: If removal of the chlorine bleach is incomplete, this cleaning reagent can seep into either your calibration standards or measurement media and cause erroneous ORP readings until it is dissipated. Always err on the side of caution in the chlorine bleach removal. Soaking the probe in clean water for periods of time longer than 1 hour can do no harm, however, lesser soaking times can cause problems.

Procedure C (Necessary only if hard deposits are present such as barnacles.)

Soak the probe for 20-30 minutes in one molar (1 M) hydrochloric acid (HCl). This reagent can be purchased from most laboratory supply dealers. Be sure to follow the safety instructions supplied with the reagent.
Wipe the platinum button by rubbing with a cotton swab soaked in the acid. CAUTION: Be certain not to damage the glass bulb of the combination sensor during this process.
Rinse the probe in clean water, wipe with a cotton swab saturated with clean water, then rerinse with clean water.
Dry the probe’s port and probe connector with compressed air and apply a very thin coat of O-ring lubricant to all O-rings before re-installation of the probe. After the probe is reinstalled, place the sensors in Zobell solution and make certain that observed ORP readings stabilize within a few minutes and remain stable for 15-20 minutes.

Källa: https://www.ysi.com/ysi-blog/water-blogged-blog/2015/11/measuring-orp-top-tips-for-the-best-data

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