Calibration Of The Redox Electrode; Redox Measurement - Tintometer Lovibond SD 335 Multi Mode D'emploi

(1)
(2)
a) b)
(3)

5 .4 Calibration of the redox electrode

It is not possible to calibrate redox electrodes, since the redox value, unlike the pH value,
is non-specific and depends on all the dissolved substances in a sample. In order to check
the sensor state of a redox electrode anyway, it can be immersed in a control solution with
a known redox value. If the absolute measurement value differs significantly from the redox
value of the control solution being used (± 40 mV), we recommend maintaining, cleaning or
replacing the electrode.

5 .5 Redox measurement

The redox measurement is carried out in the same way as the pH measurement.
The redox potential (also known as the ORP, or oxidation/reduction potential) represents
the oxidative or reductive effect of a sample and is always specified as a function of the refer-
ence electrode being used in mV. Measurement is carried out frequently using the commonly
used Ag/AgCl reference electrodes. In the literature, however, the ORP is also specified against
the standard hydrogen electrode (SHE) in order to be able also to compare measurement
values when various reference electrodes are used. In the parameter configuration either the
unit mV or mV can be selected for the redox value.
H
mV
mV
H
Conversion between
mV / mV
H
SD_335_1 10/2020
Rinse the electrode with distilled or deionized water.
And gently dab the electrode with a paper towel.
Immerse the pH electrode including temperature sensor in
the calibration solution. Ensure sufficient flow, e.g. by
a) use a magnetic stirrer with a stirring fish (recommended)
b) Sway the pH electrode in the solution.
The pH value can be read in operating mode.
Stop stirring while doing this.
Display of the redox value vs. Ag/AgCl (3 M KCl)
Display of the redox value vs. SHE
ORP vs. Ag/AgCl (3 M KCl) = ORP vs. SHE + 210 mV at 25°C
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