Sample Preparation - Xylem wtw CN 800 DIN Operating Manual

CN 800
ba15356d04 12/2021
The conditioning time depends on the previous history of
the ion sensitive electrode. To achieve a good responding
behavior, the concentration of the standard solution should
be similar to the concentration expected of the test sample.
During commissioning and after long periods of storage:
condition the electrode overnight.
Connect the electrode(s) to the meter and switch to the
measured value display (see operating manual of the
meter). The ion sensitive electrode is sufficiently condi-
tioned when the measured value no longer changes consid-
erably under otherwise constant conditions (temperature,
composition of the solution).
2 Remove any air bubbles in the bridge electrolyte by slightly knocking
against the shaft.
3 Calibrate according to the operating manual of the meter and the
analysis specification.
NOTE
Avoid measuring samples with cyanide concentrations of more than
25 mg/l, as otherwise the electrode could be damaged irreversibly. If
you expect the concentration to be higher, dilute the sample according-
ly.
In the case of an erroneous calibration immediately after com-
missioning, polish the membrane surface (see M
Malfunctions can possibly occur due to the use of a magnetic stir-
rer. If the values are fluctuating heavily, we recommend to switch
off the magnetic stirrer during measurement.

Sample preparation

Add 1 % MZ/NH3/CN solution. This sample conditioning solution creates
optimum conditions for measuring. It provides a constant ionic strength and
similar diffusion potentials at the reference electrode in standard solution and
test sample.
If you would like to have more detailed information concerning
sample preparation and measuring procedures, WTW provides
a large number of application reports for various applications.
Sample preparation
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AINTENANCE
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