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ba15356e03
09/2014
Sample preparation
CN 500 / CN 800
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 commissioning,
polish the membrane surface (see M
AINTENANCE
).
Malfunctions can possibly occur due to the use of a magnetic stirrer. If the val-
ues 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 prep-
aration and measuring procedures, WTW provides a large number of appli-
cation reports for various applications.
Response times
The response time depends on the concentration range. It is
several seconds at high concentrations,
several minutes near the detection limit.
The measured value is stable if the value does not change by more than
0.1 mV within 30 seconds.
Interferences
Complexes with Ni
2+
, Cd
2+
, Cu
2+
Strong reducing agents
Interfering ions: 10 % error with the following concentration ratio
(concentration ratio = interfering ion / measured ion):
Cl
-
I
-
Br
-
S
2-
1x10
6
0.1
5x10
3
must not be present
