Cleaning; Operating Life; General Handling Of Ph Combination Electrodes - JUMO 202710 Operating Manual

11 The pH combination electrode

11.2 Cleaning

The ion-sensitive glass membrane of the combination electrode can be rinsed
under lukewarm water. More severe pollutants can be removed using a soft
cloth and a mild household detergent.
Never clean combination electrodes with abrasive cleaning agents (scouring
powder, scouring cream, etc.) or with a scouring pad!
Deposits containing protein on the sensor part of the combination electrode
can be cleaned by being immersed in 0.1 molar of hydrochloric acid solution
(HCI) for at least 5 minutes. A protein cleaning agent (pepsin solution) can also
be employed.

11.3 Operating life

The operating life of combination electrodes depends on the operating condi-
tions. Under normal conditions and with appropriate maintenance, the operat-
ing life is at least 6 months.

11.4 General handling of pH combination electrodes

Combination electrodes should be stored in a dry place at a temperature
between 10 °C and 30 °C. Below 0 °C, the combination electrode can be
destroyed due to freezing of the electrolyte!
The sensor part of the combination electrode should be protected against dry-
ing out by using a protective cap filled with 3 molar KCl solution or a storage
holder. Lengthy storage in de-ionized (distilled) water will result in a depletion
of the KCl within the combination electrode.
Air bubbles in the membrane ball can be removed by a sharp flicking action
(like flicking a glass thermometer).
Filling up the electrolyte is not required or possible with these combination
electrodes (low-maintenance).
Before measuring and after every measurement in different media, the combi-
nation electrode must be carefully rinsed with de-ionized (distilled) water.
Clean the combination electrode after use. For pollutants containing protein,
pepsin hydrochloric acid solution (part no. 00307114) is recommended.
If the measuring function of the combination electrode has been impaired (for
example, if the display reacts very slowly):
• Check the combination electrode for air bubbles
• Function test with a second reference combination electrode
• Replace combination electrode
Solutions for calibration, cleaning, and activation can be obtained from labora-
tory suppliers.
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