Maintenance Of Electrodes - Consort C1020 Anleitung

pH electrodes
A pH electrode is active and stable only after wetting! For this purpose it must
be immersed for at least ten hours in a 3...4 M KCl solution. During short
interruptions (e.g. storage) the electrode should be immersed in a 3...4 M KCl
solution. In doing this it is always kept ready for use. When the interruption is
longer than a month, refill the closing cap with 3...4 M KCl and plug it on the
electrode tip in order to protect the glass bulb. Before use, ensure that the
reference part of the electrode is topped up with a 3...4 M KCl solution.
Avoid a low pressure inside the electrode! Therefore always remove the closure
from the refilling aperture during the measurements as well as during the
calibration. This allows the saltbridge solution to flow through the ceramic liquid
junction and prevents contamination of the electrolyte. For the same reason, the
inside level should always be higher than the outside level of the measuring
solution. Close the refilling aperture again when storing the electrode.
A polluted electrode may be cleaned with a soft detergent or 0.1 M HCl. Greasy
substances may be removed with acetone or alcohol (never do this with plastic
electrodes!).
If the electrode is polluted by proteinaceous materials (such as blood), it should
stand in a cleaning solution overnight and then be cleaned with distilled water
before use. The pH electrode wears away by being used. If the electrode tends to
respond slower and calibration becomes difficult, even after cleaning, it should
be replaced by a new one.
Metal electrodes
Metal electrodes (Pt, Ag, Au) are always ready for use. During short interruptions
they are immersed in distilled water. They should be cleaned regularly:
• Silver electrodes are immersed in a concentrated ammonia solution during one hour.
• Platinum or gold electrodes are immersed in concentrated nitric acid during one hour.
Conductivity electrodes
A conductivity cell is active and stable only after wetting! For this purpose it
must be immersed for at least one hour in distilled water. Rinse the cell always
after use and store it in distilled water (add some detergent to keep the spongy
platinum surface in perfect condition).
A polluted cell may be cleaned with a soft detergent or diluted nitric acid. Greasy
substances may be removed with acetone or alcohol (never do this with plastic
electrodes!).
Dissolved oxygen electrodes
A dissolved oxygen electrode is active and stable only when polarised! The
electrode body has almost unlimited life and requires no maintenance. After
prolonged use of the electrode, it may become deactivated. An indication is that
the electrode no longer responds correctly to calibration. In this case:
1. Carefully screw off the measuring head.
2. Cautiously remove the precipitated deposits with the aid of filter paper. Do
not use grinding paper or a glass fibre!
3. Rinse several times with distilled water and shake carefully off the water
drops.
4. Take the measuring head, fill it with new electrolyte solution and very slowly
screw it onto the electrode while holding it vertically.
5. Let the electrode rest for a few hours! The electrode is now ready for use
again.
• Replace the membrane only when damaged, NOT when calibration is no longer
possible!

Maintenance of electrodes

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